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Aeronautical Insanity Crosspost


LostCosmonaut
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This was original posted by goon Vessbot in the Aeronautical Insanity thread, but since some people here are poor and can't afford $10, I'll copy it over to here;

 

 

 


In a bid to join the ranks of the Aeronautical Insanity Effortpost Superstars, I shall write about the Streak Eagle, the famous prototype F-15 that was stripped down and pumped up in order to snatch a bunch of Time to Climb records from Communist hands in 1975. I'll cover the airplane itself, and the technique used to fly it in the record-setting flights: the Rutowski climb profile.

OFTk4s3l.jpg

Part one, the Rutowski climb profile

First, a little background. All light plane pilots and many aviation enthusiasts are familiar with the best rate of climb speed, or Vy; it's the speed at which the product of drag and airspeed is the least, and an airplane flown at that airspeed will gain altitude the quickest. By this simplistic analysis, a pilot attempting a time to climb record should simply fly at his aircraft's Vy.

But things are actually more complicated. In the way of some more background, most people are familiar with two types of energy, potential and kinetic. It's accurate enough to say that altitude is potential energy, and airspeed is kinetic energy. One can almost freely be exchanged for the other, back and forth, most familiarly as in a roller coaster. It's also what happens when a glider does aerobatics. Every time it pulls up (a “zoom climb”), it trades airspeed for altitude; and every time it dives, it trades altitude for airspeed. A powered airplane does the same thing, in addition to the constant influx of energy from its engines. In a steady-state climb (as opposed to a zoom climb), airspeed stays the same (most optimally, at Vy) while altitude constantly grows due to that steady influx.

So, here's the deal. Since airspeed and altitude (i.e., kinetic and potential energies) are exchangeable, what we are really concerned with maximizing in the shortest amount of time is total energy, or the sum of the two together. Imagine you're trying to set a time to climb record to 10 thousand feet in your Cessna 172. You  climb your airplane at Vy (79 knots) and get there in 20 minutes. Thing is, when you get to your altitude, you have a bunch of now-useless airspeed on your hands that, earlier, you could have zoomed up and converted to altitude. So, to beat you, in my identical 172, I'll climb at Vy to 9800 feet and then pull up to zoom-climb the last 200 feet, thereby losing ~20 knots and beating you by a few seconds. An even quicker way to reach 10,000 feet would be to climb at a knot or two (more probably, a fraction of a knot) faster speed than Vy, and therefore be able to start your final zoom at an earlier point than 200 feet to go.

In bug smashers, this difference is not significant because only a very small percentage of your total energy is stored as airspeed. Nevertheless, the correct airspeed to fly to maximize total (rather than potential, i.e., altitude) energy gain is a slightly faster speed than Vy, so as to take advantage of that energy store. Of course, this difference is fleeting and not worth bothering with. The fighter planes of WWI were at about the same state. But as airspeeds increased along with the march of progress, the superfighters and interceptors of the mid Cold War could store about half of their total energy as airspeed, and therefore this difference became significant. This was first noticed by a German engineer by the name of F. Kaiser, who worked on the Me-262 project.

Under the task of defending airspace or setting performance records, the prime concern is to increase total energy as quickly as possible; later you can convert it (via zooming or diving) into whatever type you actually need. This is illustrated here on a graph of airspeed (horizontal axis) vs. altitude (vertical axis.)

[timg]http://i.imgur.com/zeYcUe1l.jpg[/timg]

First, look only at the dashed curves in the background. They represent constant states of total energy. From any starting position (a certain altitude and airspeed), you can do a zoom climb and follow the contours up and to the left, ending up at a slower airspeed but higher altitude; or you can dive and follow the contours down and to the right, ending up faster and lower. Any airspeed-altitude exchange moves you along the contours (total energy remains unchanged), while any energy injected by the engines or lost to drag, moves you across the contours (total energy is gained or lost). What we want to do is move as quickly as we can across the contours up and to the right. Now look at the superimposed black blobby shape (just the outer one). It is the airspeed-altitude envelope for sustained flight of a typical fighter. Anywhere inside it, it's able to sustain flight. Naturally, the top  is the highest possible altitude, and the right side is the highest possible airspeed. As you can see, it changes with altitude. Well starting from state I, which is basically the highest and fastest you can go (remember, sustained) you can zoom up (following the contours) to state F. You've traded airspeed for altitude, and now you're going slowly, and at a much higher altitude than you can sustain. You're there for just a moment, and you'll shortly descend whether you like it or not. Likewise, from I you can dive to a lower altitude and high speed state where there's no mark on this graph, but let's say it's just a bit to the right of H, which is faster than you could have accelerated if you were at that lower altitude all along. Again not a sustainable state, and drag will quickly overcome your speed and place you back within the envelope. It is not possible to reach state G, under any circumstance.

Well that was perhaps a too-long-winded explanation of zooms and dives, but hopefully now everyone understands what's going on with your energy state. Now it's time for a little more detail.

Inside of the envelope, you'll see more contours that look like it, but getting smaller and smaller. These are different levels of Specific Excess Power, or Ps. This is the rate of gain of total energy. It's really a 3D graph, with each level of contour representing a certain Ps, just like a topographical map with contours representing terrain height. The higher the Ps, the more total energy gain per time. So obviously, we want to stay travel through where the Ps is greatest, or the hills are the highest.

Here's another example, that's a little more detailed.

wVfcqbGl.jpg

There are two regions where Ps is great: 1) Low altitude, where the air is thickest and engines are most powerful, and 2) High speed (power = thrust times speed). Between those two lies a trough due to the tremendous drag increase at/slightly above Mach 1. A standard climb profile for a lower-performance (or even higher performance, but heavily combat-loaded) jet would sit at the ridge at Mach .9.

Enter another engineer, a Mr. Rutowski, who figured out how to game this to the fullest:

q4WgAYz.png

From takeoff, you hold the plane on the deck so it accelerates, as quickly as possible, to the ridge at Mach .9. Then, you yank it up exploiting the high Ps contours at that speed as you quickly gain altitude. If this is a low-altitude record attempt, you just zoom up till you hit the target altitude and you're done. If you're attempting a high-altitude record, however, this is where things get interesting. You level off, or even descend, so as to speed up through the low-Ps trough at Mach 1 quickly. (We're losing altitude yes, but it doesn't matter because remember that it's total energy that matters, and lingering at the low-Ps region would rob you of that. Dive through it!) Next you fly level or climb at a slight angle as you pass through the high-Ps “hill” on the right side. Notice how it's oblong... that is why you fly such that the the speed-altitude plot slants up and to the right so as to take advantage of that by staying in the highest Ps level at each point along the acceleration.

Finally is the cumshot of this whole act, which this graph I found online crucially failed to show. Once you achieve the predetermined speed for the particular altitude you want to reach, you pull up into the final zoom climb to cash in that airspeed until you reach that altitude. This is the red path curving up and to the left, which I added myself (with some crappy free picture editor on a laptop without a mouse) following the total energy contours. (Also the scale is wrong, the highest record was just under 100,000 feet, and on this graph it takes us to close to 150,000. And the total energy contours stop before they get to where we are.)[edit: It didn't show the final zoom because it's not a picture of a time to climb record; it's just a picture of using the Rutowski profile to get to the highest total energy state and then being ready to do whatever from there. I added the whatever.]



A final note about the Rutowski climb profile's advantage over a conventional climb... when you have an established procedure and then come up with some way to optimize it, how much of an improvement do you expect? A few percent? 10%? 20%? Well the Rutowski profile more than doubled the average climb rate, which is a pretty stunning increase. Of course in tactical usage with a combat load they wouldn't go vertical or reverse course, but they'd still follow the same path in the graph along the high-Ps levels, with a bunt or a half-roll and pull-down to accelerate through Mach 1.

Part 2, the airplane, to come tomorrow

 

 

 


Here, let me spray some more dronechat spray

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Part 2, the Airplane

When it comes to maximizing an airplane for climb performance, the benefits of increased thrust and decreased weight are obvious. What's not obvious are the lengths that record-setters might go to achieve both of these optimizations.

Let's start with thrust:

All engines extract energy from fuel by mixing it with air and burning it. The more fuel and air, the more thrust. Throwing in lots of fuel is easy, but it doesn't do a damn bit of good without a proportional amount of air. Squeezing air into the engine is more of a challenge, and was the focal point of the development of supercharging (which itself spanned an arc of breathtaking complexity in WWII, possibly the topic of a future post). However, when you compress a fuel-air charge to a certain level in a gasoline piston engine, you get “detonation” (a.k.a. pinging or knocking to car guys) which is quickly destructive to an engine. Detonation poses a natural limit to power; in other words, the limit is set for you, and all you can do is figure out where it is, decide on a safety margin from it, and then make that the operational limit. (Not really, there are also tweaks to push detonation back, dating all the way back to the Cleveland air races, then obviously exploited in WWII, and pushed to the brink later at Reno)

Jet engines suffer no such limit. The more fuel you run through them, the hotter things get in the burner and turbine sections, and that does decrease the lifespan of the engine (due to thermal loads, blade creep, etc.). But this lifespan decrease is not a hard limit but rather a sliding scale, so the point at which you want to set the limit is arbitrary and based on your relative valuation of thrust output vs. longevity. Needless to say, when national glory was at stake, the valuation was not on longevity and the fuel governors were set for more thrust. (Later, they were reconfigured to stock settings and returned to the fleet.)

Furthermore, like piston engines, the ability to get the most air into a jet engine is not something taken for granted, so compressor and inlet design are major factors. (Nothing was modified here, as far as I know.) Environmental conditions are just as important. Naturally, we want the densest air possible, which exists at low altitudes and cold temperatures. This is why the site was chosen at Grand Forks, North Dakota, and the attempts set for January. The elevation was about 900 feet MSL, and the temperature about 0 degrees Fahrenheit at the surface.

(The inverse of this is why light plane pilots regularly get into trouble in mountainous areas in the summer:
and is a very cool topic within its own right.

Even neater note about the context.

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Goon Sunday Punch talks about nuclear rockets of various forms;

 


As promised, The Nuclear Rocket.

[timg]http://i.imgur.com/UIf5l.jpg[/timg]

Before this gets started, if you’re not familiar with the concept of specific impulse and how it relates to exhaust velocity and thrust, I suggest looking at the Wikipedia article about it as it’s a pretty important concept when talking about rocket engine designs. Very simply, it’s a measure of fuel efficiency. A chemical rocket engine like we’re all familiar with has a very high thrust but a pretty weak Isp. :iiaca: This makes it like a big supercharged V8 engine, great for climbing hills and drag racing, but it gets pathetic gas mileage. An engine with high Isp and low thrust is like a little 4 cylinder engine, it’s not going to win any races but it goes a lot further than the V8 on the same amount of fuel. With rockets, this makes chemical engines really good at taking off from Earth’s surface (climbing hills), but they eat fuel at a rapid rate.  Nuclear thermal rockets generally have lower thrusts than chemical engines but they can be much more efficient. Generally it’s a tradeoff between Isp and thrust, there are designs that have both high exhaust velocities and high thrusts but they’re uncommon and they have other problems.  

[timg]http://i.imgur.com/9WF1j.gif[/timg]
Basic operation of a NTR using the hot bleed cycle.

So, what exactly is a nuclear thermal rocket? It’s pretty simple really. You take a nuclear fission reactor and bolt it onto an exhaust nozzle. Instead of running water through the reactor and into a turbine generator, you run hydrogen through it and out the nozzle. It’s basically the same process that produces thrust in a chemical rocket, except the energy for heating the working fluid is coming from nuclear fission reactions in the reactor rather than chemical reactions between a fuel and an oxidizer. Solid core NTRs can't run as hot as chemical rockets because it would melt the reactor, but because the molecular weight of the hydrogen exhaust is so low compared to the H2O exhaust of LH2/LOX chemical rockets the exhaust velocity is higher. Also, since the energy density of nuclear fuel is much higher than that of chemical fuels, the efficiency and specific impulse of the engine is significantly better. How much better? Well, the solid-core NTRs had specific impulses of at least 1000 seconds, more than twice that of chemical designs like the Space Shuttle main engine (SSME).  As an aside, using hydrogen as a propellant in an NTR gives the best exhaust velocity (due to its low molecular weight), but there’s no reason you can’t  use other propellants since its just being used as reaction mass. Ammonia, methane, carbon dioxide, nitrogen, or just plain water, you can run practically any non-corrosive fluid through the reactor to produce thrust. This is really handy if you want to, say, fly a mission to the rings of Saturn. Once you get out there you can find a nice chunk of ice to melt and siphon into your propellant tanks for the trip back, you don’t need to haul massive amounts of fuel around for the whole mission if you can top up the tanks when you get to your destination.

The history of the US nuclear rocket programme begins in 1955 with project Rover. The principal R&D work was carried out at the Los Alamos laboratory, with the goal of producing reactor fuel systems that would operate with hydrogen at temperatures above 2200K. Initiated by the US Atomic Energy Commission and the US Air Force, the original goal was to create a nuclear engine for missile applications. However, in 1958 the newly formed NASA took over responsibility for the project and the proposed engine was to be used in long-haul space missions to the moon and Mars. Progress was unexpectedly rapid, it proved to be much easier to reduce the reactor size and weight than was initially thought.  Phase one of Rover produced the Kiwi graphite-core reactors, named for the flightless bird. First tested in 1959, Kiwi proved that a small lightweight reactor operating at high temperatures and cooled by hydrogen was essentially viable. The Rover project went on to be very successful and produced a number of small, powerful reactors.

[timg]http://i.imgur.com/yHQhA.png[/timg]

Reactor designs produced under the Rover programme.

[timg]http://i.imgur.com/XDMXW.jpg[/timg]
Kiwi-A reactor.

[timg]http://i.imgur.com/XB887.jpg[/timg]

Kiwi cutaway illustration.

[timg]http://i.imgur.com/lg7bH.gif[/timg]
Kiwi-TNT, destructive test of the reactor carried out by deliberately taking it supercritical as quickly as possible. Kiwi-TNT was conducted to test a worst case scenario of a reactor explosion on the launchpad. The reactor exploded 156 milliseconds after the control drums were rotated to the fully ‘open’ position. The explosion released an intensely radioactive cloud of debris. Anyone within 400 feet would have received a fatal dose of radiation. January 12, 1965.

[timg]http://i.imgur.com/Nk4Z8.jpg[/timg]

Shattered remains of graphite fuel elements from destructive reactor test.

 Since the reactors operated at much higher temperatures than more traditional reactors they were considerably more powerful, and with each new reactor the power density increased. The Phoebus-2A reactor test in 1968 ran for more than 12 minutes at 4000 megawatts, at the time it was the most powerful reactor ever built. In 1960 the NERVA programme was initiated and in 1963 it was tasked with taking the graphite-based reactor developed under Rover and creating a functioning nuclear rocket engine.

NERVA

[timg]http://i.imgur.com/V4IzP.jpg[/timg]
NERVA mockup.


NERVA reactor cutaway illustration.

[timg]http://i.imgur.com/nykpF.jpg[/timg]

[timg]http://i.imgur.com/Gl3jl.jpg[/timg]


The flight engine configuration was 22 feet tall from the upper thrust structure that mates to the hydrogen tank, to the exhaust bell nozzle. The spherical tanks beneath the upper thrust structure contain actuating gas for the engine’s pneumatic systems. Just beneath those is the gimbal assembly that allows the rocket to be steered. The turbopump machinery is located in the lower thrust structure. The aluminium pressure vessel contains the reactor and beryllium radiation shield. There’s no radiation backscatter in space so the internal shadow shield combined with the hydrogen propellant tank was considered to be enough radiation protection for the payload. The mushroom-looking things on top of the pressure vessel are the actuators for the reactor control drums. The exhaust nozzle mounted beneath the reactor is cooled by the hydrogen propellant flow.

[timg]http://i.imgur.com/BfPGm.jpg[/timg]

[TIMG]http://i.imgur.com/xizZC.jpg[/TIMG]

Radiation flux from an operating NERVA engine.

[TIMG]http://i.imgur.com/TfYbh.jpg[/TIMG]
NERVA cold flow test. The rocket engine assembly contained no fissionable material for this test. Startup operations and operation procedures were the main goals of the test. December 1, 1967.

[TIMG]http://i.imgur.com/Ecm4x.jpg[/TIMG]

Same test as above, this is the first NERVA test engine, the XECF. CF for cold flow. December 1, 1967

[timg]http://i.imgur.com/gXkMi.jpg[/timg]
NERVA engine undergoing test firing at Jackass Flats. Note the lack of any containment of the exhaust plume.

[timg]http://i.imgur.com/XLsN4.jpg[/timg]

NRX-EST engine on the test stand.

Between 1959 and 1972, 23 Rover/NERVA reactor tests were carried out at Jackass Flats in Nevada, about 160km west of Las Vegas. For most of these tests there was no attempt to contain the exhaust plume. The NERVA engine proved to be very reliable, the XE-prime (last engine in the NERVA series) was tested with flight hardware under simulated vacuum conditions and operated for a total of three hours forty eight minutes, with 28 restart cycles. The engine burn times were limited by the size of the hydrogen tanks at Jackass flats, not the capabilities of the engine. The longest continuous burn time was 90 minutes, and it was extrapolated that reactor lifetime could exceed 3 hours of operational time.  XE-prime demonstrated that a nuclear rocket engine was suitable for space flight and could operate with twice the specific impulse of chemical rockets. NASA deemed NERVA was ready to begin flight tests.

[TIMG]http://i.imgur.com/Qm7Ry.gif[/TIMG]
[timg]http://i.imgur.com/KTVr8.gif[/timg]

[timg]http://i.imgur.com/z1D11.gif[/timg]
Configuration of the NERVA reactor core. The narrow propellant passages limit the engine’s mass flow rate and hence its maximum thrust.


RIFT
The NERVA engine was to be flight rated by mounting it as a third stage on the Saturn V, this configuration was known as the S-N (Saturn Nuclear) stage. Originally planned in 1962, the Reactor In Flight Test was to be mounted on a Saturn V with a dummy S-II second stage, so the nuclear rocket engine was supposed to fire while still suborbital, with the reactor splashing down in the Atlantic. Note that this was a flight test, orbital testing was to be carried out if everything panned out with the suborbital tests. NASA mission planners proposed using NERVA for a manned mission to Mars, the impressive capabilities of the nuclear engine made such missions feasible. It was also proposed for lunar missions, using a nuclear third stage the Saturn C-5 could carry three times the payload of the chemical version. Ultimately the Mars mission was to be NERVA’s downfall, RIFT was delayed continually after 1966 and public interest in human spaceflight was waning after the space race was won. Congress was not willing to commit to decades of expensive development for a manned Mars mission, and RIFT was never authorized. The Saturn production line was shut down in 1970 and with no Saturn-N to perform flight tests, NERVA was effectively dead.  Nixon shut down the NERVA programme in 1972 after expenditures totaling $1.4 billion.

[TIMG]http://i.imgur.com/oNfAt.gif[/TIMG]

Proposed nuclear configuration of the Saturn C-5.

[TIMG]http://i.imgur.com/tCRVf.jpg[/TIMG]
[TIMG]http://i.imgur.com/tEdO3.jpg[/TIMG]

[TIMG]http://i.imgur.com/3uyym.jpg[/TIMG]
RIFT illustrations.

[TIMG]http://i.imgur.com/bq42v.jpg[/TIMG]

NERVA as the engine for a Saturn V upper stage.

[TIMG]http://i.imgur.com/qLVNT.gif[/TIMG]
Lockheed proposals for the applications for the NERVA engine.

The original NERVA reactor was based on Kiwi as developed under project Rover; though the later reactors were more powerful by the time they were developed the Apollo programme had already been largely defunded and the money for NERVA was running out. But in the early 1960s, enthusiasm for manned space exploration was still high and many NASA mission planners saw NERVA’s impressive performance statistics and incorporated it into their proposals. Extended lunar exploration and manned Mars expeditions were the two main focuses of attention. Chemical rockets are unworkable for deep space missions with large payloads, you need huge amounts of fuel to boost the large payloads necessary for manned expeditions, then you need more fuel to boost that fuel and the vehicle size spirals out of control. NERVA was much more efficient than chemical designs and could run for long periods with multiple shutdown/restart cycles, which made it perfect for deep space missions. Modular propulsion units were designed, with an engine and propellant tank package multiple modules could be combined to build a vehicle for a specific mission.

[TIMG]http://i.imgur.com/QYsz1.jpg[/TIMG]

NERVA propulsion module illustration from a NASA report to congress.

Advanced designs

NERVA wasn’t the only NTR design under development. Dumbo was a competing design that was by some measures even better than NERVA. NERVA had a thrust to weight ratio of less than 1, so it could never be used to take off from the Earth’s surface. This was due to the design of the propellant channels through the core that greatly restricted the mass flow rate. Dumbo had a totally different core design and had a T/W ratio as high as 60. It also had a higher Isp than NERVA of around 960 seconds. It should be noted that the T/W ratio is only really important when you’re talking about accelerating out of a gravity well, greater thrust lets you escape more quickly and lowers losses to gravitational drag. Out in deep space its much less important than specific impulse, which is why ion thrusters for example are popular despite their extremely low thrust. Dumbo was shelved due to a cost cutting decision that forced both NERVA and Dumbo to use an existing nozzle design that had been developed for NERVA. Unfortunately this nozzle design was incompatible with Dumbo and that was that.

[timg]http://i.imgur.com/QcRqS.jpg[/timg]
Dumbo reactor cutaway. Sorry about the image quality.



The performance of a nuclear thermal rocket is limited by the temperature of the reactor core. Higher temperatures means higher exhaust velocities which means higher specific impulse. But you can only run the engine so hot before the fuel elements start melting. So then some smart engineer asked the question, “What if the reactor was already molten?” Then you get a liquid core nuclear thermal rocket, with a much higher core temperature and correspondingly higher efficiency. If you’re going to the trouble to deal with a nuclear reactor with a fluid core, you might as well go for broke and build a gaseous-core nuclear rocket rather than mere liquid. As the name implies the fission reactor core is so hot it’s in the gaseous state, or even plasma. The reaction chamber temperature is around 25,000°C. Hydrogen is vented from the chamber walls (to keep them cool, you don’t want the uranium gas to touch the reactor walls) into the centre of the nuclear inferno where it flash boils and shoots out the exhaust nozzle. The problem is the uranium tends to shoot out the exhaust as well, which lowers efficiency and angers environmentalists. There are several containment schemes you can use, in one open cycle design the fission reaction is maintained in a vortex designed to minimize the loss of uranium out of the nozzle. Core containment was a serious engineering hurdle but the gains are worth it, an open cycle gas core NTR can achieve specific impulses of up to 3000 seconds and high thrust. Or you can spin the reactor like a centrifuge which encourages the uranium to stick to the outside of the chamber instead of leaking out the exhaust. A closed cycle gas core NTR doesn’t have the same problem, the gaseous uranium is physically contained so it can’t escape out the exhaust. One design from the 1960s is the “nuclear lightbulb,” so called because the fissioning uranium is contained within quartz bulbs that transmit the radiant energy of the reaction to heat hydrogen gas surrounding it. R&D work was carried out by the United Aircraft Corporation, they even produced some hardware.

[timg]http://i.imgur.com/FFEFi.gif[/timg]


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[TIMG]http://i.imgur.com/HLuRp.jpg[/TIMG]

Nuclear lightbulb illustrations.

The reference engine design had seven bulbs, each 6 feet long by 2.3 feet in diameter. The engine operated at a pressure of 500 atmospheres. There were severe engineering difficulties with the design, from how to inject the uranium fuel into the reaction chambers, to designing a reactor core to deal with temperatures far in excess of the melting point of any known material. I don’t want to go too in depth because this post is long enough already, but suffice it to say that while the engineering challenge was considerable it was not insurmountable. United Aircraft ran a number of physical experiments with their design, and demonstrated the feasibility of the design and materials. Since operating a genuine uranium plasma reaction was somewhat beyond the scope and funding of their contract with NASA, they used an 8000°C argon plasma with water as the coolant in a subscale test. The results of the tests were encouraging, but more development was needed.

[TIMG]http://i.imgur.com/f0d77.jpg[/TIMG]
[TIMG]http://i.imgur.com/LE8S0.jpg[/TIMG]

[TIMG]http://i.imgur.com/ybScg.jpg[/TIMG]
[TIMG]http://i.imgur.com/EdjtR.jpg[/TIMG]

United Aircraft’s test hardware.

The nuclear rocket is an engine looking for an application. No one’s talking seriously anymore about manned exploration of the solar system, which is pretty much the ideal scenario for the NTR to really shine. NERVA worked. Political opposition to nuclear technologies and public apathy toward human spaceflight combined to kill NERVA before it could get off the ground (literally), but the technology is still there, and with modern materials and engineering techniques we could make it work even better than it did in the 1960s. If we want to seriously talk about going to Mars, the nuclear rocket can take us there. I haven’t really gone into detail about the sort of missions planned that used nuclear thermal propulsion, but these images show the sort of thing being proposed.

Nuclear Flight System Definition studies, 1971:

[TIMG]http://i.imgur.com/xepa5.jpg[/TIMG]

[TIMG]http://i.imgur.com/3gZAc.jpg[/TIMG]


[TIMG]http://i.imgur.com/GUrc2.jpg[/TIMG]

[TIMG]http://i.imgur.com/3Da8v.jpg[/TIMG]


Integrated Manned Interplanetary Spacecraft, Boeing design for a Mars expedition using NERVA nuclear stages, 1968:

[TIMG]http://i.imgur.com/pWNNA.gif[/TIMG]

[TIMG]http://i.imgur.com/AzDVe.jpg[/TIMG]


And don't think that the Soviets weren't developing their own nuclear rocket engines!
[timg]http://i.imgur.com/Mn4UV.jpg[/timg]

 
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  • 3 weeks later...

Goon powercube posted this in the Aeronautical Insanity thread quite a while ago, and I just now noticed it;

 

 

 


Aerobus?  Maybe we should've just bought the L1011 after all
ySsJBxk.jpg?1
When my friend took this picture at a restaurant in Miami- he thought it was a hoax. Oh how wrong he was.

The 1970's were a time of economic malaise for the West. Weirdly, the Soviet Union was chugging along at its own egregious and bizarre pace - Soviet air travel needs had never been more pressing. Millions of Warsaw Pact and Soviet citizens needed to shuttle around the Iron living room. In fact, Aeroflot celebrated its first hundred millionth passenger year in 1976. This called for larger aircraft. Engine technology issues were holding up Ilyushin's domestic design that we now know as the extinct IL-86.

The program to which the IL-86 stemmed from was formally known as the "aerobus". The IL-86 was not supposed to be the only aircraft of the family of short,medium, and long haul indigenous widebody aircraft.

Okay, I should clarify here- the Aerobus requirement probably originated around 1967- I refer to the 1970's as the Soviet's lack of urgency and spate of terrible commercial engines delayed any real possibilities until that time anyway.

Tupolev had stepped up to offer the Tu-184, an aircraft that was similar to a twin-aisle Dassault Mercure. Thankfully, at the time of its inception Andre Tupolev was still alive. He took one look at it and decided that Tupolev should not waste any resources on what he was sure would be nothing but a reputation-wrecking disaster. Not that Tupolev was immune to civil aviation failures, they are simply beyond the scope of this article. They were also, usually, swept under the rug and blamed on Myashischev.


The IL-86 itself was originally supposed to be a widebody IL-62. Same T-tail, roughly similar cabin-window layout, and identical engine positions. The Soviet government stepped in and said that the design "looked antiquated". That was the end of that. The next set of aerobus edicts demanded wing mounted engines and a "modern" six to eight piece flight deck window set. Would the original IL-86 studies have been more successful than what the Soviets ended up with? Probably not, there was really nothing in their engine arsenal that had the bypass ratios to produce either the thrust or the necessary efficiency. If that was not enough the government, suspicious that airports in Siberia would not be able to offload baggage quickly, demanded that their precious aerobus had something eventually dubbed система багаж с собой" luggage at hand" system. In other words, passengers would check their own bags in after boarding through airstairs built into the lower deck. During the latter days of the IL-86, this was never used. Well, it was a bit more imaginative than that. The actual goal was to take aerobus even further. The passenger would buy their glorious soviet travel token a mere five minutes before departure from a kiosk. They would then walk onto the ramp, hang their coat, and either check their bag with the valet in the luggage room- or put it next to them. This is also why the IL-86 had no overhead bins.

A brief interlude about the Kuznetzov NK-8
A terrible engine that almost killed the hopes and dreams of the Ty-154A, B, and IL-62A. It was a hurriedly designed low by-pass turbofan essentially created so that the Soviets could say that they had one. I understand why Nikolai Kuznetsov took the project as he was the best choice to design it- but even he knew it was not a great engine. I cannot find any appropriate historiography to illustrate what he probably thought seeing it strapped to a widebody aircraft. But with a bypass ratio of ~1.5:1 and only 20klbs of thrust per engine it was nothing but a disappointment.
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Seriously? I mean, look at that compressor, 1956 called!

Back to our regular program

As the IL-86 was going nowhere- the Soviets, in a rather landmark move reached out to America. McDonnell Douglas balked. Lockheed, suffering from their own engine issues, and always a company interested in earning political capital- decided to send an L1011 to Moscow in March 1974.

In what, at the time, must have come as a surprise - the Soviets decided to order 30 L1011. They also wanted to build up to 100 per year. It would have been a landmark order in monetary terms, and probably changed some of the dynamics of the cold war. Can't have that now, can we? Mr. Peanut stepped in and changed the rules at the last second. Sadly, even a swamp rabbit could not bite any sense into him. He had the DOD and Department of Commerce investigate any potential ITARS issues. Naturally, there was a tangential one. The RB-211 engine used composite fan-blades. The Soviets had no industrial process for that, nor did they ever consider it a wise idea (something Rolls Royce probably wished they had decided). The deal, as if by design, failed.

If that was not enough, the Department of Commerce also vetoed the sale of General Electric CF-6-50 engines. The Soviets had planned to use this engine in their own indigenous widebody projects. The soviet high-bypass engine solutions were running behind schedule. The L1011 deal would have allowed them the necessary time to properly develop an iteration of the IL-86, probably CF-6 powered. When Soviet engines of the same thrust class were ready, there would be indigenously powered versions only.

Strangely, if the deal had gone through, the Soviet Union (then Russia and the former Republics) would actually have not only been the largest operator of the L1011- but also built far more than the parent designer.

The Russians, feeling rather jilted and already in possession of measurements and actual Lockheed L1011 documentation decided to not let this fact get them down. Being the largest, oldest, and most politically active OKB of the Soviet Union, Tupolev decided that they could step up. If it was not clear, this work was to be done both to replace the first iteration of the IL-86 as well as to augment it.

Having said that, this design was so far from clean-sheet, Antonov, Yakovlev, TANKT Beriev, and even Myashishchev were also told to do the same. I should clarify a bit. Outright design copying was actually strictly forbidden. It was a very strict code amongst Soviet engineers that they would always come up with an indigenous solution. Indeed, building too many copies of the Me-262 cost Semyon Alekseyev his design bureau, resulting in the shuttering of OKB-1, and the unfortunate creation of the Baade 152. I say that they did not let the documentation and measurements they had go to waste because the requirement from the government was almost literally "You will build us an L1011. It will be this long, or longer." Not much freedom there.

Yakovlev managed to lose all its civil credibility just as the project was gaining momentum. The series of disasters with the early Yak-42s all but sidelined them from any L1011 cloning.

Myashischev, deciding to do what they always did, ignored the RFP and decided to draw pictures of what a five year old would think an airplane would look like after being fed a package of gummy bears.
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Yes, this is the M-52. No, it never flew.

By the late 1980's, when Myashischev had run out of money, the resulting M-52 is something that lacks polite description. The project was only allowed to continue for so long as the passenger pod could be replaced with relevant, heavy, space-related payloads.

TANKT Beriev, much like Myashishchev- thought the best way to get anywhere with the project was to bring it into a realm they could understand. That realm, as for most things Beriev was water. While I cannot directly source just how many of their 1970's to mid 1980's lifting body flying boats were 100% attributable to the aerobus specifications, there were definitely 3-5-3 (500 seat) models described in the brochures as "aerobuses"

Now that we have seen what the perennial also-rans of Soviet experimental design companies came up with- it is time to look at what the adults designed. I should mention that by the 1970's, at least in the case of Myashischev, when they actually designed something correctly the projects were usually stolen and put under the stewardship of more mature OKB.

Guess what! They all look like L1011. So much so that I've started to call them Tri-Zvezdy.

 
7slRLoe.jpg

The most fascinating part of this saga is that Tupolev's L1011esque widebody passenger aircraft was to be called the Tu-204. Except this Tu-204 was going to sport high-bypass engines made by Lotarev, and seat between 350 and 400 people. As you can probably see, it included some fairly distinctive Tupolev passenger aircraft features. If the engines had matched their prospective performance targets (and they did to some degree, these are the same engines that eventually became the Ivchenko-Progress D-18Ts used on the AN-124) the aircraft would have had a range similar to that of the L1011-500. I am told that the registration on the model indicates that Tupolev believed that the latest they would get their superstar into service with Aeroflot was 1987 or 1988.

Eventually, Tupolev realized that Ilyushin had the "larger than twin" aircraft market locked down and turned the Tu-204 into more of an A330-size aircraft. Still, seen as too large- it became the aircraft we know today.
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That there would have been the AN-318

Antonov, somewhat a stranger to the widebody world, took some advanced papers on wing-related induced drags- and thought the solution was to take a design almost identical to the above Tu-204 and put winglets on it.  It was not a bad idea, their version would have had a longer range.
The thing is, much as Tupolev was encountering- the Soviet Union was running out of money, quickly. The government was more often than not picking the losers of the competitions because they were cheaper. Seeing the writing on the wall, many of the OKBs decided to work on purely commercial, and potentially exportable, aircraft. Many of them focused entirely on business jets (a topic for another day), Antonov bucked that trend and decided to pull an XC-99 on the AN-124.
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The AN-418 was, as you can see, supposed to be a 600 seat VLA.

All of those were great ideas, why were they never made? Politics. Ilyushin was always able to convince the government that whilst their current IL-86 was vastly underperforming and experiencing issues operating in cold climates- the real IL-86 was just around the corner. What also saved the IL-86 was that it had such a huge amount of floorspace, that the military loved the idea of using it for various crazy projects. There was one for testing a Soviet Airborne laser, one was tested to be the equivalent of America's E-6B mercury. It had space, it could be inflight refueled, and it was "off the shelf". Eventually saner generals realised that the sheer amount of fuel it would need to stay airborne on long missions was impossible to carry along with mission specific equipment. I admit, the cleanish sheet L1011 clones would not have been cheap and came to be right when the Soviet union was going broke, but with proper negotiation skills, some wood could have at least been carved for a full-size mockup.
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Yeah, okay, someone got an extra pair of jeans for this.
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Imagine this aircraft with the same NK-8s!
What were some of these IL-86s, you ask? Well, one had two decks with 600 passenger capacity. Most amazing of all, it still seemed to have been powered by Kuznetsov NK-8s. Eventually, engine technology advanced, the Soviet Union collapsed, and the closest thing to the original IL-86 and Aerobus brief took flight; the IL-96. They, immediately decided to offer a twin-deck variant for that.


Eventually, around the mid-1980's even Ilyushin decided that they could build a widebody with Lotarev D-18s.
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One version was fitted with what I can only describe as a thrusting APU.

I know the IL-86 lumbered around the Soviet Union and former Soviet Republics for a good thirty years longer than planned. It was always a cheap way to get 400 drunk Russians to Antalya. I would just say that Ilyushin over-promised and under-delivered.

Sometimes, I sit back and daydream about what would have happened if the L1011 deal had gone through. Would I have flown to Pyongyang on an Air Koryo, Voronezh built, Tristar? Wouldn't that have looked amazing!
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Since the airliner post was met with a less than thrilling reception, here's a post by goon Mr. Chips on Soviet interceptors;


There are Graveyards Full of Sukhoi Pilots – the Story of Sukhoi’s Early Jet Fighters

The 1950s were certainly very interesting times in the Soviet aviation industry; like their rivals in the West, it seemed as though technology could not only keep pace with the imaginations of aircraft designers, but exceed it in many cases.  Good thing too, as it seemed as though there was always a need to devise an aircraft capable of flying faster, higher and further than ever before...there was an arms race on, don’t you know!
In no area was this constant one-upmanship more evident than in the perpetual cat-and-mouse game between bomber aircraft and the interceptors tasked with seeking them out and destroying them.  New technologies such as the atomic bomb and the jet engine meant that the days of massed formations of slow and vulnerable bombers were over; the fast, high-flying jet bombers armed with nuclear weapons would be flying, at least in part, by themselves or in very small formations, relying on their speed and altitude for protection (and your gun turrets, if you’re flying a Tupolev Tu-95 “Bear).  Even with early warning from radar, the need for a fast-climbing interceptor capable of speeds not even dreamt of was needed, and it was needed yesterday.

Pavel Sukhoi – A Copycat Turned Good (Or Else!...Love, Josef)

Pavel Sukhoi’s career as an aircraft designer didn’t seem to show a whole lot of promise initially.  After freeing himself from the yoke of one Andrei Tupolev, Sukhoi used his connections in the government to help him set up his own design bureau; free to create whatever he wanted but most importantly, free from that patronising old goat Tupolev.  If there was one thing that Sukhoi wanted to work on, it was fast aircraft – he didn’t care for what, he just wanted to make fast things.  His very first aircraft, the Su-1, was one of the first aircraft ever designed in the Soviet Union to use a turbocharged piston engine – most designs of the time relied on engine-driven supercharger instead – and not just one turbo, but two of them.  Unfortunately, the Su-1, while fast for its time, had serious reliability issues from the turbos and was otherwise inferior in every other way to rival designs from Mikoyan, Lavochkin and Yakovlev.  As if to put the program out of its misery, a pair of accidents early in the test program sealed the fate of the Su-1 for good.  
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[super]Sukhoi Su-1; more turbos than your fighter![/super]
Working ever further to satisfy his obsession with speed, Sukhoi had a considerable interest in hybrid propulsion; not batteries and propellers and “Save the Whales” stickers, but pistons, turbines and everything between.  His first experiment with hybrid propulsion, the Su-7, combined a large radial piston engine with a rocket engine.  While the rocket dramatically increased the speed and altitude of the Su-7, it was troublesome, to say the least; the program ended after the sole Su-7 was destroyed at altitude when the rocket motor exploded, killing the pilot in the process.  Despite the failure, the Su-7 was awarded the First Order of the Stalin Prize, presumably for demonstrating a novel method of dispatching enemies of the state.
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[super]Sukhoi Su-7; first experiment with hybrid propulsion.  Should have been the last.[/super]
  The later Su-5 wasn’t much of a success either; this aircraft combined a conventional V-12 piston engine driving not only a propeller, but a ducted axial compressor as well.  The air from this compressor was then fed to a combustor, heated and expanded, then discharged out of a nozzle from the back of the aircraft.  
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[super]Sukhoi Su-5; a bad idea carried out to its illogical conclusion.[/super]
This so-called “motorjet” engine was, as it was in previous experiments elsewhere, a total failure.  A gas turbine compressor needs a huge amount of power to work properly, and no aircraft piston engine ever came close to putting out enough power to drive even a small compressor.  As such, the motorjet engine was at best a noisy, inefficient zero-sum game.

Fortunately for Sukhoi, real jet engines were now at hand, and like every other designer in the Soviet Union, they struggled with how best to utilise this new engine.  Initially, both Yakovlev and Mikoyan simply took one of their piston-engined fighters, threw out the piston engine and glued the jet engine in its place, with the exhaust exiting underneath the cockpit.  Sukhoi, on the other hand, took a more pragmatic approach to the problem.  Heavily influenced by captured Messerschmitt Me-262s, he designed his next aircraft, the Su-9, to very closely resemble the Me-262; after all, if it worked for Ze Germans, why not for us Soviets too?  
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[super]Sukhoi Su-9; Messerschmitt would have sued if Steve Jobs ran the place.[/super]
Unfortunately, the Soviet government was very cool to the aircraft; the Su-9, despite being a rather docile aircraft to fly, was far slower than rival designs from Mikoyan and Yakovlev, to say nothing of the eyebrows raised by Sukhoi’s copied design.  Having been quickly and quietly declined the production go-ahead, Sukhoi revised the Su-9 and followed up with the Su-11.
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[super]Sukhoi Su-11; Slight changes spoiled everything.[/super]
 While nearly 70 miles per hour faster than the Su-9, it had none of the good flying manners of its predecessor; it flew so badly that none of the fixes Sukhoi attempted remedied the Su-11’s alarming lack of stability.  Undaunted, Sukhoi proposed yet another design; a twin-engined, swept-wing, all-weather interceptor, designated the Su-15.  While it sounds fairly conventional by any standard, JUST LOOK AT THE THING:
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[super]Sukhoi Su-15; Yeesh.[/super]
Mercifully, the Su-15 prototype (unsurprisingly) crashed in March of 1949, taking with it not only the Su-15 program, but the entire Sukhoi design bureau along with it.

We Need Aircraft, But Do We Seriously Need to Bring Him Back?

Well, yes I guess we do.  After Stalin’s untimely murder departure, Pavel Sukhoi lobbied the government extensively to head up a revitalised Sukhoi design bureau.  Ultimately the Politburo relented and allowed Sukhoi to restart his operation, presumably on a very short leash.  Understanding that another failure would likely result in a “long-term assignment” to Siberia, Sukhoi set about designing a pair of supersonic fighter aircraft concurrently; the first, intended as a tactical fighter, the second, a high-speed, high-altitude interceptor.  Both aircraft were designed to very closely follow the recommendations from the Central Aero- and Hydrodynamics Institute (TsAGI) for a supersonic fighter, and both were powered by a powerful new afterburning turbojet engine from Arkip Lyulka’s engine design bureau.  However, there was one key difference between the aircraft; the tactical fighter used a highly swept wing, while the interceptor used a triangular wing.
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[super]Sukhoi S-1 flying over Tushino Air Show, 1956[/super]
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[super]Sukhoi T-3 three-view.  Not exactly a looker.[/super]
Designated Aircraft “S” (S for “strelstrelovidniy” or arrowhead) and Aircraft “T” (T for “treugolniy” or triangular), these aircraft moved ahead at considerable pace – Aircraft “S” ultimately became the Sukhoi Su-7 “Fitter”, one of the most successful fighter-bomber families of the Soviet arsenal, if not anywhere in the world...after it went through one of the most difficult service introductions of any aircraft in history.  
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[super]Very early Sukhoi Su-7 “Fitter”.[/super]
The Su-7 never really flew properly from the get-go; control forces were very heavy and takeoff and landing performance was rather poor.  Combine that with bad pneumatic brakes and poor runways and you have a recipe for accidents...and that’s even before you get to the unreliable engine or the serious aerodynamic flaws of the first aircraft.  It is estimated that something like 80% of all Su-7A crashes stemmed from some design fault in the aircraft, something that wasn’t remedied until the much improved Su-7B entered service.

Back to Aircraft “T”, though...development work continued apace, and by May of 1956, the prototype, designated T-3, flew for the first time.  The T-3 was a very hot aircraft – even with an interim version of the Lyulka AL-7 engine, it achieved a top speed of nearly 1300 miles per hour in short order.  At the same time a revised version, the PT-7 (which was given even more engine power and fitted with better radar than the T-3) seemed poised to enter production when on 4 July 1956, the CIA performed the first U-2 overflight of the Soviet Union.  Understandably pissed off from this, the Soviet government told Sukhoi to scrap their plans for the PT-7 and come up with something even faster and higher flying; something that could threaten the U-2.
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[super]Sukhoi T-43, the prototype for the Su-9 interceptor.[/super]
The new aircraft, the T-43, was revised heavily in several aspects; the fixed radome of the T3/PT-7 was moved into a moving “shock cone” in the engine air intake (allowing for both a larger radar as well as far better high-speed performance of the aircraft itself).  An even more powerful derivative of the AL-7 engine was fitted, and any extraneous weight was stripped from the design – for the first time, a Soviet fighter aircraft would not be armed with any kind of guns...only missiles.  In addition (and presumably to the delight of Pavel Sukhoi himself), provision for a liquid-fueled booster rocket was provided as well.  Mercifully for the test pilots, the rocket motor program ran into considerable difficulty, and it was also found that the T-43 possessed incredible performance without it anyways – it could fly at speeds in excess of Mach 2 and reach altitudes as high as 71,000 feet on jet power alone.  Delighted with the performance of the T-43, the Soviet government rushed the aircraft into production in October of 1960, designating it as the Su-9 (again).  NATO, having seen the T-3 fly at the Tushino Air Show four years before, designated this new aircraft family the “Fishpot”.  In addition to building and deploying the Su-9, the Soviet Union made the decision to integrate the Su-9 into their first automatic detection and interception system; essentially their equivalent to the Semi-Automatic Ground Environment (SAGE) system then in service with the North American Air Defense Command.
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[super]Sukhoi Su-9 “Fishpot” ready for a mission[/super]

A Manned Missile, Perhaps Literally

The Su-9, despite breezing through the flight test program with relative ease, experienced considerable difficulty on entry into service.  First of all, the aircraft was very complex and required very careful maintenance; the PVO (the Soviet Air Defense Force, responsible for all radars, SAM sites and interceptors) had no experience with such an aircraft before, and was considerably behind the eight-ball in terms of practices.  The aircraft itself had a number of very serious issues to overcome as well:

-Relatively high weight combined with a relatively small wing made takeoff and landing speeds incredibly high – on the order of 230 mph(!),
- Extremely limited fuel; the aircraft carried enough fuel for a mission profile of 45 minutes at the most, so careful planning and execution was the order of the day,
-The aircraft had a number of very serious and unpleasant handling characteristics at both the top and the bottom of the speed envelope, and
-The ejection seat had a minimum safe speed and altitude of 310 mph and 500 feet.

Combined with an initial lack of a two-seat trainer version (which would come later) the Su-9 suffered an absolutely appalling loss rate throughout its career – numbers are virtually impossible to come by, but it is thought that roughly 500 of the 1100 Su-9s built were lost to accidents in total, most of them being related to engine failure on takeoff or runway overrun on landing.

Despite these flaws, perhaps the biggest flaw of all in the Su-9 was with its radar and armament.  Aircraft-mounted intercept radar sets were primitive in the 1950s and early 1960s, no matter where you looked, but the R1L radar fitted to the Su-9 was primitive even by those meagre standards.  The radar set had a maximum detection range of roughly six miles; you would probably see the B-52 you’re intercepting before the radar can pick it up.  Then, once you have said B-52 all lined up, you now have to rely on one of the worst air-to-air missiles ever fielded, the K-5, known in the West as the AA-1 “Alkali”.

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[super]K-5/AA-1 “Alkali” air-to-air missile.  For when getting out of your interceptor and punching your opponent isn’t quite hard enough.[/super]
The K-5 was a radar-guided missile, but unlike the contemporary AIM-4 Falcon or the AIM-7 Sparrow, that use semi-active radar guidance, the K-5 is known as a “beam-rider” missile; meaning, it seeks out the radar beam from the attacker and follows it all the way to the target.  The issue with this is that it requires the attacker to maintain radar lock on the target the whole time.  Added to that, the K-5 had an engagement envelope of between one and four miles, which was so close to your target that you could practically throw your kneeboard through one of their engines, which you’d probably have to do anyways because the K-5 was terribly unreliable – standard procedure was to shoot two K-5s at a time to compensate for this – and your only other option was to ram your target, what with no guns and all...

A Do-Over

So the Su-9 was fast but incredibly flawed, and in the 1960s it seemed as though Sukhoi was falling out of favour with the Soviet Air Force and the PVO, both of whom seemed to prefer designs from Mikoyan-Gurevich and Yakovlev.  In a bit of a Hail Mary play, Pavel Sukhoi proposed a highly advanced interceptor capable of flying even faster and (fortunately) further than the Su-9, with the ability to carry the latest radars and missiles then in the inventory and on the drawing board.  Having spent a considerable amount of time creating several revised versions of the Su-9, Sukhoi rolled out their T-49 prototype.  A very large aircraft, fitted with the huge Oryol radar (the same radar fitted to the Yak-28 and Tu-128 super-heavy interceptors) while retaining the single AL-7 engine as the Su-9.
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[super]Sukhoi T-49 prototype.  Like many Sukhoi prototypes, it has a face only a Russian mother could love.[/super]
The T-49 quickly lost the “Dee” style intakes and opted for a more conventional square intake, complete with variable intake ramps, now feeding two Turmansky R-11 engines (the same engines fitted to the MiG-21).  This new aircraft, designated the T-58, was also a fair bit larger than the Su-9 or even the T-49. By revising the intakes in the T-58, it freed up a considerable amount of fuselage space for fuel – the T-58 carried up to 15,000 pounds of fuel, as opposed to 6,500 pounds in the Su-9 – a welcome addition indeed.  
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[super]T-58 three-view[/super]
However, the original Oryol radar proved to be unsuitable in nearly every way, and the design had to be revised again, this prototype carrying the designation T-58D.  Also, considerable effort was made to tame the T-58D’s landing characteristics; the outer wing sections were fitted with a 45-degree sweep section (as opposed to a uniform 60-degree sweep), and boundary layer control, in which engine bleed air is piped over the wing flaps to dramatically increase their effectiveness, was fitted as well.  The result was an aircraft that finally flew more or less properly across its entire speed range.  This new aircraft, designated the Su-15 “Flagon”, entered limited production in 1966, with the T-58D-derived Su-15T entering production in 1969.
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OH GOD NOT YOU AGAIN GET OUT
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OK, that’s better....

Smarting from their decision not to field a two-seat version of the Su-9, Sukhoi and the PVO very quickly fielded a two-seat version of the Su-15, designated the Su-15UT.  Interestingly, the Su-15UT retained full combat capability with no penalties to speed or range, highly unusual for any Soviet trainer aircraft.
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[super]Sukhoi Su-15UT two-seat trainer taxiing by a single-seat Su-15T.[/super]
The Su-15 had a rather, erm, action-packed career.  Despite being considered a “second-string” interceptor behind the MiG-23 and MiG-25 and spending most of its life chasing down reconnaissance balloons, the Su-15 nonetheless was a participant in nearly every incident in which the Soviets either intentionally or accidentally downed a civilian aircraft, including both Korean Air Lines incidents (the first a 707 being forced down in Siberia in 1978 and the second being KAL 007 in 1983).  
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[super]Sukhoi Su-15TM patrolling for balloons, wayward airliners...[/super]
Interestingly, by the time the KAL 007 incident took place, the writing was on the wall for the Su-15; by this time, the Su-27 and MiG-31 had flown and were approaching service entry in a few years...at that point, the Su-15 was likely to retire.  Geopolitics came into play once again, and the collapse of the Soviet Union gave the Su-15 a stay of execution, soldiering on until 1995.

An interesting aside to the Su-15/T-58 story is that of the T-58VD.  The T-58VD was a proposed V/STOL version of the Su-15.  
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[super]Sukhoi T-58VD V/STOL interceptor prototype.  Notice the open doors exposing the lift engine intakes.[/super]
In place of some of the internal fuel, a trio of Koliesov turbojets were mounted vertically in the fuselage, the idea being to reduce or completely eliminate the takeoff run of the Su-15.  Like most lift-jet based V/STOL projects, this project was not pursued beyond the prototype phase.  But that’s another story for another time.

COMING SOON: The Booze Carrier

 
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  • 3 weeks later...

I'm not sure if this is worthy of it's own post and lacking better options, I am leaving this here. 

 

New Zealand-based Martin Aircraft Company is already taking orders for ‘world’s first practical jetpack able to be flown by a pilot or via remote control’

 

The link is to a UK Guardian article but any Google search of Jet Pack will bring up dozens of recent news articles in the last 24 hours.

 

 
 
The company website has some neato looking photos and videos.
 
 
Including this one.
 
 
The Dream of the 1960s is finally alive!
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I'm not sure if this is worthy of it's own post and lacking better options, I am leaving this here. 

 

New Zealand-based Martin Aircraft Company is already taking orders for ‘world’s first practical jetpack able to be flown by a pilot or via remote control’

 

The link is to a UK Guardian article but any Google search of Jet Pack will bring up dozens of recent news articles in the last 24 hours.

 

 
 
The company website has some neato looking photos and videos.
 
 
Including this one.
 
 
The Dream of the 1960s is finally alive!

 

This is the weakest shit, man.

 

I mean, these doofusses have spent almost a decade working up to what amounts to a baby ducted fan VTOL. Meanwhile, this problem had been solved in 1969

 

B8sD1wQ.jpg

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Powered by high molar H2O2 monopropellant if memory serves.

 

Anyone who doesn't want to get flung through the sky by a pressurized tank filled with flesh-melting chemicals is a goddamn pussy.

 

FOOF or bust. All I'm saying is if you're not hypergolic with your jetpack fuel (and oxidizer if relevant) even in Antarctica you're not a man and you're in a society that says only men can be totally awesome.

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Oh.  Quite.

 

I wonder if nozzle efficiency and hot gas ingestion are issues.  A compressor stall can't be fun when it's strapped to your back.

There was a joke* I saw somewhere that might explain why it wasn't considered that much of an issue.

 

That said, you raise a very valid point. I wonder if an upwards-facing inlet leading to the intake would have been too inefficient, or if it would have marginally increased lift?

 

 

 

*

"What is the technical term for a flying infantrymen?"

"Skeet."

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According to my book (amazon link), Kingfish would have had about the same top speed as the A-12, Mach 3.2 (pg. 181), while having about 700 miles less range, and slightly higher cost (also, the government was more confident in Lockheed's ability to deliver the aircraft on time and work in a highly secretive environment). The Mach 4 figure appears to be for an earlier variant of FISH (First Invisible Super Hustler) that would have been air launched from a modified B-58.

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