Microfighters and other Air stuff coming from Romania

[steppewolfRO]

So I'm back on forums and I'm throwing a post hoping on a debate about an interesting concept, the micro fighters, MIG-21 being the best known model. Here is a short presentation of the concept and some theoretical perspectives made by some Romanian air engineers. 

 

This idea come into debate looking to replace the aging fleet of Mig-21 Lancer, a plane which was not demanding from financial point of view while being in decent number (around 80 at some point), packed a decent punch for 2000s being BVR capable too (albeit missiles weren't bought, at least officially) and most importantly the maintenance was made entirely at local level. This remained the only fighter after MIG-23, MIG-29 and IAR-93 were phased out. It was an enigma why MIG-29 was so quickly phased out (1989 - 2003 in service) and some of the unofficial reasoning was high maintenance cost and dependence on Russia, low life spawn of engines plus ground attack limitations.

 

In middle 2005 started the debate about replacing the MIGs with Gripen, Eurofighter, F-16s or Rafales and after some delays due to economical crisis the final decision was to acquire a squadron of F-16 A/B upgraded. This means a big hassle for FAR (Romanian Air Force) since it has to deal with new air base and runways, new procedures, pilots training for a very different plane which is completely different from anything was operated until now. The first squadron is on course of becoming operational and there are talks about two more squadrons both of 18 planes which will be also F-16 but the type is unclear. Some rumors say they want more F-16A/B upgraded , some say F-16 C/D, other are talking about some Israeli ones. 

 

The second project seem to be MLU of IAR-99 trainers announced by MoD after the research Institute was talking about a technological demonstrator probably not unaware of the intentions of defense planners. They are hoping even for a new engine and some redesign of the fuselage to accommodate it.

 

MLU of IAR-99 seem a good idea and even is an AESA radar seem a waste on such plane it still could be useful in CAS role with some long range missiles like Brimstone while delivering a much cheaper training to fighter pilots. I can't envisage other role for this plane in next decades. 

 

Now back to micro fighters, it seems that with the technology from IAR-99 TD and MLU, a new aircraft is planned, a micro fighter as it was named in the article I linked above. How viable would be a micro fighter in the next 30-40 years outside the advanced training scope? 

 

Yeah I'm back around these forums after a hiatus  I hope you're all well! 

 

 

 

[Toxn]

Hi, welcome back.

 

I like the idea of microfighters, but I feel that trying to make a supercruising stealth version might be a step too far.

When you end up with situations like "we can't fit anything into the bays, better develop an all-in-one AA missile/AG missile/bomb" you should probably know that you've bitten off more than you can chew.

[Sturgeon]

YAY! @steppewolfRO is back!

[Sturgeon]

I think it depends what you ask of your microfighters. If their job is fundamentally as interceptors for airspace control, supported by ground radar, they are probably fine. Besides that, it's hard to believe they would be competitive as air superiority vehicles.

However, Romania's role in war should help shape this. Is Romania essentially looking to support a larger operation by a superpower? If so, maybe a lightweight fighter/trainer type aircraft wouldn't be such a bad thing. It could carry tactical weapons, defend airspace, and support allied operations. If the maintenance was reasonable, this would be a useful capability, and a small fighter could do it.

[Toxn]

11 hours ago, Sturgeon said:

I think it depends what you ask of your microfighters. If their job is fundamentally as interceptors for airspace control, supported by ground radar, they are probably fine. Besides that, it's hard to believe they would be competitive as air superiority vehicles.

However, Romania's role in war should help shape this. Is Romania essentially looking to support a larger operation by a superpower? If so, maybe a lightweight fighter/trainer type aircraft wouldn't be such a bad thing. It could carry tactical weapons, defend airspace, and support allied operations. If the maintenance was reasonable, this would be a useful capability, and a small fighter could do it.

If you look at the link, this thing is supposed to be tiny. Like, smaller than an F-5 levels of tiny.

 

I'm honestly not sure that it could do anything useful at that size aside from maybe training.

[Zyklon]

While the idea seems good, i think its just too small to work well, especially since they also want to have an internal weapons bay on it which just kills its range.

And also while LO is going to shorten engangement ranges by a bit, it surely isn't sparing you from BVR

[steppewolfRO]

Well, the study regarding the micro fighter is more of an unofficial one. I am however perplex they are considering as a starting point the old Viper engines from IAR-93 or IAR-99. Must be some sort of nostalgia for not finishing the previous project or new planes being scrapped in early 90s as IAR-93 which reached maturity by the time it was pulled out of Air Force.

 

The other part which may look like nostalgia is the ground based guidance system which reminds me of MIG-21 Lazur. It is a pretty old system, not used anymore which would make the plane unlikely to be sold to other countries. And again I think it is some sort of nostalgia involved although they may have some point since Romanian radar network is one of the few area which was kept at the highest standard in last decades. Anyway to summarize, the setbacks would be:

 

- load out too small, limited to short range IR AAM or air to ground small guided rockets or bombs

- limited range

- limited weapons and avionics

- no radar   (but can an IRST replace it?  or other passive sensors?) 

- no chances to be sold 

- special weapons to be created 

- BVR capability is no longer optional

 

strong points would be:

 

- cheap

- locally build

- suitable to hit and run tactics 

 

The last discussions about this concept lean to a two engine and new ones which can be easily acquired now Honeywell F124/5-GA-200, FJ44-4 or GE J85-GE-21B depending on the solution (twin engine or single engine). The LO elements aren't completely new field for Romania. Some attack helicopters prototypes from before 1989 were test bed for redesigned engine exhausters for reduced thermal footprint, surfaces designed in such way that allow the installing of radio absorbent panels (which were subject of a prize at Geneva technical fair before 1989) and also a short time in the 90s.

 

I guess there is a concern to resume some activity to the 3rd aviation factory Romania have. The other two are set pretty well. Aerostar Bacau is doing maintenance for a large type of planes (MIG-21, L-39, Boeing 737) and is scheduled to be able to make for F-16s as well, especially if our neighbouring NATO countries will acquire same type of plane. IAR Brasov (Puma maintenance and upgrade) have a collaboration with Eurocopter to assemble H215M and signed recently a MOU with Bell Helicopters so it's well set for future. The article I linked have a small inaccuracy as new helos are expected to replace only IAR-330 SOCAT and not the entire fleet of PUMAs as Venom is not exactly a transport helicopter therefore we expect to see H215 M as well although a better militarized version than the one Europcopter is proposing right now. Add to that that old PUMAs still have a sizeable resource. 

 

Avioane Craiova was the loser of the post 1989 as IAR-93 was retired in 1998 (a stupid decision if you ask me) and IAR-99 trainer although pretty modern was built in a small number and wasn't exported as support of government was non-existent. On short term they will probably make an upgrade or MLU to existing IAR-99 trainers of FAR (Romanian Air Force) to make them suitable to prepare F-16 pilots. But on long term I think there is mandatory to build new planes. I wouldn't go from first to a jet especially considering there is a need for a small transport plane to replace the An-2 fleet which was retired but never replaced for both civil or military aviation and there are projects to which they have worked but which are now stopped (an interesting one is a sea plane for transport with firefighting capability).

 

The current project to build a technology demonstrator for a new trainer and use the experience to upgrade current IAR-99 fleet and try to build a new trainer in the future which is a very ambitious if not impossible right now project and nobody knows the exact requirements other than they want an AESA radar on it so I'll try to speculate what type of plane it would be viable also for sales point of view. The intention is to have a fleet of 52 F-16s in next 4-5 years and maybe the debut of acquisition process of a F-35 squadron after 2025 while the trainer will be at least for a while IAR-99 which have now Lancer's Israeli avionics. 

 

But the market is kind of saturated by trainers so maybe makes more sense to just assemble an already mature project. Than a trainer without single seat light CAS/fighter doesn't make sense as Romania needs a second line plane and cannot afford the luxury to fly trainers without a significant combat ability. For NATO countries there is Hawk, M-346, Czech L-39NG/159 and even Kai T50 plus some research projects such as MAKO or Textron Scorpion (which may the most interesting option if Bell rotary wing deal will be good and there will be a history of collaboration between Romania and Bell although what this plane does best is more a thing for UAVs in the future). For the other side there's Hongdu, Yakovlev, JL-9. 

 

So what a new trainer/light fighter-bomber should look like to i. be useful for FAR ii. be attractive to be sold to countries with cheap fighter requirements? I would like the following (mind, I'm not a specialists):

 

- Ability to operate from improvised runaways. 

 

I think this is the feature to start with since the approach , at least in helicopter's case is to assume the main air bases will be heavily attacked hence the secondary ones or even improvised ones will need to be used. Add to this is that target customers aren't the rich ones. This probably means no low mounted wing and inlet air cones for engines to be placed in a protected position, maybe above the wing?  

 

- BVR capability -> supersonic speed

 

With a clear requirement to have AESA radar I don't see why you should not use this for BVR and if it can make this than it is desirable to be faster than sound. Naturally the radar will be helpful in delivering AGMs as well. I am not sure if this is a must but imo if you put such a good radar on it better make the most of it. More it could be capable of hit and run tactics that some parts of military seem to look for. Not sure if this is a must. 

 

- Maneuverability 

 

A trainer needs this. 

 

- Front line missions

 

some limited AA interdiction and delivering long range payloads (Brimstone, Spike NLOS ?) 

 

What else?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Ramlaen]

Trainers that can double as light attack or CAS in permissive airspace are underappreciated.

 

I would like the USAF to merge the T-X and OA-X programs.

[Sturgeon]

@steppewolfRO is there anything you could license produce locally?

[Collimatrix]

I don't think the microfighter concept is a strong one with current technology.  I also think that fighters designed by small countries are at a very large disadvantage because of the current state of engine technology.  This wasn't always the case, but it is the case now.  Sweden made fighters that were perfectly competitive with those of the USA and USSR throughout the Cold War, and during WWII small nations like Romania and Australia managed to turn out fighters that were perfectly competitive with those of major powers, at least for a time.

I should clarify that I mean "small" in the sense of economic power, not land area.  The UK and Japan could both turn out decent fifth-generation fighters in the near future if they decided it was a priority (UK more easily than Japan).  

The main problem is that state-of-the-art jet engines can only be made by a handful of companies.  Only those companies have the experience and expertise to design and produce the high temperature components of a top-of-the-line jet engine.  John Golan's Lavi book explains that the Israelis were confident that they could produce every single component of the Lavi except the engines.  The Lavi was not low-tech, far from it.  The entire fuselage was to be filled with Digital Radio Frequency Memory (DRFM) jamming devices, the nose would contain a look-down-shoot-down radar, and the wings would be made of aeroelastically tailored carbon fiber composites.  All of this stuff was comparably advanced to anything the US or Soviets had airborne at the time, and in some cases (notably the wing composite structure and jammers) it was better.  But they categorically could not make the engines in Israel.  In fact, any license-production of the engines would amount to mere assembly of knock-down kits of engine components.

 

In order for a jet engine to have better efficiency and power density, the core inside the engine needs to experience greater temperature gradients:



The Y axis is pressure and the X axis is volume.  Pressure multiplied by volume is work, so the entire area enclosed by the diagram is the work the engine produces.

Since a gas increases in temperature when it is compressed, improving engine performance necessarily entails the use of materials that can withstand greater temperatures.  Current top of the line gas turbine blades are made of mono-crystal nickel alloys, and those are a stone cold bitch to make.  Only a handful of companies worldwide can do it. 

 

 

But these exotic, difficult materials aren't just a luxury.  They're fundamental to achieving a high performance thermodynamic cycle.  A jet engine can certainly be made that doesn't use these exotic nickel alloys, but they're bigger, heavier and less efficient than one that does.  Check out this comparison of a GE F404 with a GE J79:



The earliest versions of F404 produced nearly as much thrust as the last versions of the J79, and later versions eclipsed it entirely, all while being narrower, much shorter, slightly more fuel efficient, and requiring enormously less maintenance.  Mono-crystal nickel alloy blades are the sine qua non of modern jet fighter engines.
 

Off the top of my head, there's one company in the UK that can make these things, two in the USA, one in France, two in Russia and one in China, but they're still getting their feet under them.  The Japanese have enough expertise in industrial turbines and exotic materials science that I think they could figure it out if they threw a huge wad of money at the problem.  India is trying to develop independent expertise, but... it's Indian defense.

This means that any country that wants to develop a new fighter that is not on the list above has to make do with engines from a country that is on the list above.  This means that a lot of the fundamental decisions about the aircraft are made for them.  At what altitude and airspeed will the fighter be most efficient?  A small country that can't design engines has to choose from a handful of already available engines and hope that the parameters of the existing designs closely match what they want.

 

There is also the possibility that the small country doesn't get the engine they want at all.  SAAB is stuck with a weaker version of the General Electric F414 for the Gripen E/F that only produces 98 kN.  Since the Gripen E/F is quite a bit heavier than earlier versions, this leaves it somewhat underpowered.  General Electric had calculated that, with enough development money, they could develop a souped-up variant of the F414 capable of producing 120 kN of thrust.  They pitched this idea, called the F414 EPE, to the US Navy as an upgrade for F/E/A-18E/F/G-e-i-e-i-o fighters.  The US Navy was initially interested, but ultimately decided to spend the money elsewhere.  So SAAB is stuck with an underpowered Gripen E/F and can't do anything about it, as they're not really in a position to spend the megabucks that GE will want for engine development.

 

Another problem is that the current air warfare paradigm doesn't really favor small fighters.  I wrote a post about the effects of scaling on fighter performance on another forum, so I'll copy-paste it here:

 

Quote

Imagine that you can just freely scale an aircraft up or down in size. We'll ignore the fact that real engineering doesn't work this way at all, just imagine you could. The entire plane, wings, fuselage, engine are all enlarged or shrunk by some linear factor.

The top level speed of an aircraft is the speed at which the force of drag (which increases with airspeed) matches the force of thrust provided by the engine. Since the forces are equal and in opposite directions, they cancel out and the aircraft cannot accelerate anymore.

What happens if we take a fighter and scale it up? The force of drag is a product of the coefficient of drag (at a given airspeed) and the frontal area of the aircraft. The coefficient of drag is a function of the shape of the aircraft, and we're just scaling the plane up, so the drag coefficient stays exactly the same. So the zero lift drag at any airspeed will increase proportionally to the frontal area of the aircraft, which is a square function of how much the aircraft was scaled up.

But the thrust isn't going to scale like that. Just scaling up the engine and maintaining power density (note: this is not a responsible way to design gas turbines outside of thought experiments) will mean that the thrust the fighter has will increase as a cube function of the scaling factor. Cubes increase faster than squares. Therefore, all else being equal, a bigger fighter is a faster fighter.

But this is a pretty ridiculous level of simplification. You don't just scale planes up and down. For one thing, even if the plane is being scaled up and down, the pilot stays the same size. And it follows that the ejection seat, and the cockpit, and the canopy, and the life support system and everything else that has to do with the pilot ought to stay the same size too. And since we're talking fighters, there are a bunch of other combat systems to consider. A jammer that can protect a seven ton fighter isn't really significantly lighter than the jammer required to protect a twelve ton fighter. A gun that's deemed adequate to kill enemy fighters and strafe ground targets for a seven ton fighter is likewise still adequate on a twelve ton fighter. The navigation, IFF, and a bunch of other avionics don't really need to be scaled up either. So if we make a bigger fighter, there's going to be a lot of weight left over, proportionally speaking, because not everything needed to be scaled up with the airframe.

That means that larger aircraft have more available weight for fuel storage. Therefore, all else being equal, a bigger fighter is a longer ranged fighter.

But what about maneuverability? This is where things stop favoring the heavier aircraft. The amount of Gs an aircraft can pull is a function of its maximum lift divided by its mass. Assuming uniform density as an aircraft is scaled up, the lift will increase as a square function of the scaling factor, since lift is wing area times lift coefficient times a bunch of other garbage. But, assuming uniform density, the mass of the aircraft will go up as a cubic factor. Therefore, all else being equal, a bigger fighter is a less maneuverable fighter.
 

 

From simple physical scaling effects, smaller fighters should have an edge in maneuverability but should be at a disadvantage in terms of range and speed.  With the fifth generation of fighter jets emphasizing supercruise capability and long range (in order to help compensate for small fleet sizes), a relatively small fighter is not looking like a great trade-off.  There are other problems with micro-fighters under the current fifth-generation paradigm.  Radar performance (range, resolution) is directly related to the size of the antenna.  Bigger fighters can support a larger radar.  Internal weapons bays are more or less a must for stealth, and a small fighter is going to have a much harder time supporting internal bay that can carry all the sorts of ordnance it might need to carry.

The hybrid light strike/trainer concept has more merit, but I am not sure that this idea is a wise allocation of resources.  Combat aircraft designers have moved towards multi-role designs that double as fighters and as attack aircraft because individual aircraft have become more expensive and because mission electronics have become so much better.  But aerodynamically speaking, a multi-role aircraft is not an attractive idea.  In order to have the requisite agility needed for air to air combat, fighters need to have lots of features that compromise their efficiency.  Fighters have huge wings, proportionally speaking, so that they can produce lots of lift.  They have vortex generators like canards, dogteeth and LERXs to allow them to pitch to very high angles of attack.  They have gigantic vertical stabilizers, ventral fins and other auxiliary and oversize control surfaces to maintain control while they are performing extreme maneuvers.  All of this stuff improves agility, but adds weight and drag.  A light strike aircraft that doubles as an advanced trainer might be able to perform useful missions in a strike role (as the L39 albatross is today in Syria), but it won't do very much in an air-to-air role.  If, in any realistic war, it would just be killed in any sort of contested airspace, it makes more sense to stop pretending that it can double as some sort of fighter, and get rid of all of the features that make it more agile, and just use it as a light bomber.  Better still, make it a drone.

 

I think that is the balance of considerations based on modern technology.  Changes in technology could change this balance a lot.  For instance, General Electric is working on silicon carbide turbine blades, since mono-crystal nickel alloy blades are nearing the limits of their potential.  Once the silicon carbide technology is mature, it might turn out to be much easier to produce than the mono-crystal nickel alloys.  It is also possible that computers and CFD software will improve to the point where institutional experience in engine design matter less, and small nations will be able to reasonably design and produce their own fighter jet engines.  But that is speculative.  For right now, I think fighter aircraft are really only competitive if they're fairly big, and if they come from fairly big nations.

[Toxn]

I heartily agree with the above, although I think there is scope for trainer/light bomber hybrids even where drones are in play. But then I think you end up with something boring like a Tucano rather than a baby F-35.

 

A small nation wanting good capability for cost would honestly be better of developing drones and AA/SAM missiles for home production and consumption. Which, funnily enough, is what most of them are doing these days.

[Xoon]

On 8/12/2018 at 7:56 PM, Toxn said:

I heartily agree with the above, although I think there is scope for trainer/light bomber hybrids even where drones are in play. But then I think you end up with something boring like a Tucano rather than a baby F-35.

 

A small nation wanting good capability for cost would honestly be better of developing drones and AA/SAM missiles for home production and consumption. Which, funnily enough, is what most of them are doing these days.

*Kongsberg NASAMS intensifies*