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LostCosmonaut

1960s NATO VTOLs

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Just about everyone has heard of the (in)famous F-35B VTOL aircraft, along with its predecessor the Harrier. The Soviets also dabbled in vertical takeoff aircraft throughout the latter half of the Cold War. However, did you know that during the 1960s, NATO seriously considered developing a supersonic VTOL strike fighter? It was thought that airbases would become unusable after the first hours of the war, so having a VTOL strike aircraft would allow NATO to continue striking at Soviet ground forces.

 

Numerous designs were proposed. One of the most sane the P.1154.

 

p-1154_rn_hk_0021.jpg

(a conceptual image of the P.1154)

 

The connection between the P.1154 and the Harrier (via the Kestrel prototype) is easy to see. The P.1154 was itself developed from the earlier P.1150, the original contender for the NATO strike aircraft competition. Like the Harrier, the P.1154 uses a single engine to provide thrust for both vertical takeoff and horizontal flight. This is in contrast to most designs of the era, which used dedicated lift jets. Though the P.1154 was never built, it was a major technological step in the development of VTOL aircraft.

 

 

Mirager_IIIV.jpg

The Mirage IIIV is clearly derived from the highly successful Mirage III airframe. However, it can be seen that lift jets have been added in the fuselage aft of the cockpit. No less than eight (!) lift jets are located in the fuselage, in addition to the single main engine. This would certainly have been a maintenance and reliability nightmare, especially in the austere environment of an ongoing (possibly nuclear) conflict. Unlike the P.1154, the Mirage IIIV actually made it to flight status, with two prototypes undergoing testing during the 1960s.

 

EWR_VJ_101_in_1964.jpg

 

The West German VJ101 was an attempt to convert the F-104 Starfighter into a VTOL aircraft. Like the Mirage entry, the VJ101 had lift engines (two in the central fuselage). However, it also had pairs of engines in swiveling pods on the wingtips, which could vary their angle to direct thrust downward or forward (similar to the Bell D-188A. Like the IIIV, the VJ101 made it to flight, and was tested extensively (it has been claimed that the aircraft was capable of supersonic flight without afterburner). With six engines, including four in moving nacelles, the VJ101 would also have been difficult to maintain and keep active.

 

fiat-g-95-6.jpg?w=830

 

The G.95/6 was the Italian entry (read more about it here). It was the ultimate development of the G.95 VTOL design, which went through several iterations (the G.95/3 resembles a VTOL F-101). In terms of layout, it was closest to the Mirage IIIV, with main engines for forward thrust (two of them) augmented by multiple lift jets (six in this case). Like the other VTOL aircraft, it would have been difficult to maintain, produce and keep reliable. Additionally, like the French and German designs (and the Yak-38), it would have suffered all of the drawbacks associated with lift jets, namely that they are dead weight for 90% of the flight.

 

 

The failure of the NATO Supersonic VTOL program of the 1960s shows the difficulty in making VTOL practical for a military aircraft. It would take until the 1970s for a subsonic VTOL combat aircraft to be successful (the Harrier), and until the 2010s for a supersonic VTOL aircraft to become workable.

 

 

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You forgot the VAK-101, you heathen! That thing would have been at least as bad as the Yak-38!

 

You mean the VAK-191B? It was pretty similar in stats and layout to the Yak-38 but one of the lift engines was moved to the tail section instead of having both of them up front. It was intended to be a strike fighter with a secondary dash-to-intercept role, and like the Yak-38 turned out to have crap performance.

NT6mGKr.jpg

 

There was also the Do 31 transport, which was intended to be used to supply rough airfields operating the aforementioned VTOL fighters. The internal pods each housed a Rolls-Royce Pegasus engine (same as the Harrier) and the outer pods each have four Rolls-Royce lift engines as used on the Mirage and VAK191B. Useful load would have been around 3,500kg.

nnOWy4E.jpg

ir6tRdT.jpg

 

It also had a large analogue-digital hybrid computer for preforming the differential equations needed for takeoff/landing.

ggmVjo1.jpg

 

(Interestingly the lift engines found a much longer life on the Hawker Trident airliner, being mounted conventionally in the 3B version to give the airplane a boost in thrust for takeoffs in hot conditions.)

 

Lockheed also made a couple joint ventures. They cooked up the CL-704 with the Shorts Brothers, which was a F-104 Starfighter, the main engine would have been replaced by a more powerful Rolls-Royce Spey, while the tip tanks would each be replaced by 7(!) lift engines. It was canceled due to the development of the Kestrel/Harrier, to the presumable relief of the wives of Marine aviators. I can only imagine how quickly it would go through it's fuel with seven lift jets and the bigger Spey engine.

YTh25QR.jpg

hOHNgQb.jpg

 

And the Ryan triangle wing proposal. From what I can find the triangle was intended to spin around like a helicopter blade for takeoff, then lock into position for regular flight.

Poq5gu4.jpg

X0kNqVV.jpg

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Lockheed also made a couple joint ventures. They cooked up the CL-704 with the Shorts Brothers, which was a F-104 Starfighter, the main engine would have been replaced by a more powerful Rolls-Royce Spey, while the tip tanks would each be replaced by 7(!) lift engines. It was canceled due to the development of the Kestrel/Harrier, to the presumable relief of the wives of Marine aviators. I can only imagine how quickly it would go through it's fuel with seven lift jets and the bigger Spey engine.

YTh25QR.jpg

hOHNgQb.jpg

 

One wonders why these tip jet proposals didn't choose alternative methods of vertical thrust for the tip lift. Rockets with drop LOX tanks seem like they might even be lighter.

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FzOGgzB.jpg

 

The Lockheed XV-4 Hummingbird in formation with a T-33.  This aircraft initially used ejector tubes that were supposed to entrain a larger amount of airflow an augment VTO thrust.  These performed much less than calculations had suggested, and the plane was later switched over to lift jets.  The Rockwell XFV-12 also was to use ejector lift, and in that case it also performed far less than originally calculated.  What's with that?

 

hqdefault.jpg

 

The US Army was for some time interested in the XV-4, this before the agreement that the Army wouldn't have any fixed wing aircraft fun.

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FzOGgzB.jpg

 

The Lockheed XV-4 Hummingbird in formation with a T-33.  This aircraft initially used ejector tubes that were supposed to entrain a larger amount of airflow an augment VTO thrust.  These performed much less than calculations had suggested, and the plane was later switched over to lift jets.  The Rockwell XFV-12 also was to use ejector lift, and in that case it also performed far less than originally calculated.  What's with that?

 

hqdefault.jpg

 

The US Army was for some time interested in the XV-4, this before the agreement that the Army wouldn't have any fixed wing aircraft fun.

Man, calculations are only as good as the stupid hairless apes calculating them. Wannabe bet "calculations" involved translating horizontal thrust to the Y-axis without accounting for loss of engine power due to poor airflow?

One single missed link thanks to a lack of imagination from a dirty ape, and you get this sort of failure. That's just the way it is.

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Man, calculations are only as good as the stupid hairless apes calculating them. Wannabe bet "calculations" involved translating horizontal thrust to the Y-axis without accounting for loss of engine power due to poor airflow?

One single missed link thanks to a lack of imagination from a dirty ape, and you get this sort of failure. That's just the way it is.

True in general, but I sort of think this particular issue might have had more to do with the fact that boundary layer aerodynamics are black magic and the calculations cannot encompass all the fuckery that turbulence will do to ejector efficiency.

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True in general, but I sort of think this particular issue might have had more to do with the fact that boundary layer aerodynamics are black magic and the calculations cannot encompass all the fuckery that turbulence will do to ejector efficiency.

 

You're right, and my analysis may have more to do with the difference between 4 and 8% ABV than something something something hairless apes and their limits at mathematics.

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You're right, and my analysis may have more to do with the difference between 4 and 8% ABV than something something something hairless apes and their limits at mathematics.

Expensive drinking ho!

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Is less than 10% so goddamn expensive in South Africa, for fuck's sake?

We're the land of SAB, so the concept of beer not being a 4-5% lager took a while to filter into our heads.

 

When it did, we apparently all decided that slapping a 'craft beer' label on a bottle means that you can double the price at will.

 

Hence, anything over 5% = double price.

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Another similar "huh we just don't know why it's not working" failure was the XFV-12, designed for the Sea Control Ship.

VGCp88W.jpg

Nf5qNtu.jpg

 

Lab tests showed 55% thrust augmentation should be expected; however, differences in the scaled-up system dropped augmentation levels to 19% for the wing and a mere 6% in the canard.[1] While the augmenters did work as expected, the extensive ducting of the propulsion system degraded thrust, and in the end the power-to-weight ratio was such that the engine was capable of vertically lifting only 75% of the weight of the aircraft in which it was mounted.

 

Convair also proposed a great looking light fighter for the Navy. The model 200 would have had a F100 with a F-35 style three-section rotating exhaust plus two 10k lbf lift jets (The Rolls-Royce ones on the previously mentioned aircraft had around 5k lbf) behind the cockpit, while the Model 201 would have been a conventional fighter.

 

gigZG6u.jpg

DVFAJns.jpg

lHuGwzu.jpg

 

(The tiltwing in the back looks to be a Canadair CL-84)

 

And apparently after General Dynamics bought up Convair they further refined it's lines into the Rafale Model 218.

XPSLIhe.jpg

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    • By LostCosmonaut
      During the 1960s, both the USSR and NATO countries had many programs for the development of VTOL aircraft. Most of these never reach flying status, though a few did fly at least in prototype form. One of these was the Ryan XV-5 Vertifan.
       

      http://modelingmadness.com/scott/korean/xv5photoa.jpg
       
      Development of the XV-5 began on November 10, 1961, when the US Army issued a contract for the development of an aircraft using the lift-fan propulsion system. Primary contractors were General Electric and Ryan Aeronautics. The lift-fan system was quite different from other VTOL systems of the time, such as the lift jets found in the original MiG-23 prototype or contemporary VZ-4, for instance. Rather than the jet exhaust directly providing the thrust for vertical flight, the exhaust drives several fans, which provide the thrust for vertical lift. This has the advantage of not projecting hot exhaust gases downward, however, there are losses in efficiency due to the extensive ducting needed.
       
      The XV-5 (orignally designated VZ-11 at the start of the program) was powered by a pair of J85 turbojets, the same engines as found in the F-5. Maximum takeoff weight was 12,500 lb. Space for two crew members was provided. Two large lift fans were located in the wings, which provided most of the thrust for vertical takeoff. A smaller lift fan was located in the nose, which provided additional thrust as well as attitude control. The vanes on each fan could be pitched between -7 and 45 degrees to provide directional control while hovering. As the XV-5 would spend much of its time in hover, the test aircraft were fitted with helicopter style controls, to provide better handling while taking off and landing vertically.
       
      Two XV-5A test aircraft were formally accepted by the US Army on January 26, 1965, and began flight testing shortly afterward, at Edwards AFB.
       

      http://vertipedia.vtol.org/vstol/images/VSTOLWheel/pics/41.jpg
       
      The XV-5A demonstrated the ability to land and take off vertically, as well as successfully transition to horizontal flight (transition took place at about 170 km/h). However, there were some issues. The aircraft's ground attitude meant that taking off perfectly vertically was quite difficult; it require the pilot to release the brakes, adjust pitch controls, and change engine power simultaneously. Additionally, the aircraft was found to be difficult to control during the transition period, as there was no integrated control system for both modes of flight. Often, the XV-5A would pitch up or down for a few seconds as the transition occurred. Numerous other small issues were noted; many instruments were poorly placed, and cockpit temperature control was ineffective. More importantly, visibility downward was very bad when hovering. Oddly, a parking brake was not fitted to the XV-5A, which caused issues during testing.
       

       
      The XV-5A had decent conventional takeoff performance, with a takeoff run of about 800 meters needed. The aircraft also performed well during conventional landings. However, during vertical takeoffs and landings, severe turbulence was noted while in ground effect, making the aircraft difficult to control. This made it difficult to land in a precise spot (a major problem for an operational VTOL aircraft), and limited operations to when winds were less than about 10 km/h, obviously unacceptable for operational use. Another problem noted with vertical flight was that at high loads, the lift fans would reingest exhaust gases, leading to loss of power similar to vortex ring state. Despite these flaws, the XV-5A was judged adequate by the US Army as a research aircraft (however, it was recommended that these issues be fixed in follow-on research aircraft).
       
      The first XV-5A aircraft was lost in an accident on April 27, 1965, which unfortunately killed the pilot testing the aircraft. Investigation showed this was likely due to the pilot accidentally switching the aircraft from horizontal to vertical flight mode (the switch was located on the collective control for convenient access, which made it easy to activate accidentally). Testing continued afterward with the second prototype. Later in the testing, the XV-5 was considered by the US Army for use as a close air support aircraft or as a rescue aircraft (the lack of hot exhaust gases meant that it could hover over people without inadvertently frying them). The second fatal accident in the XV-5 program occurred in 1966 during testing of this capability. A rescue harness was ingested into the lift fan on the left wing of the XV-5A, damaging it. The pilot ejected, but was killed as the seat deployed horizontally due to the attitude of the aircraft during ejection. Later investigation showed that the damaged fan was still capable of producing enough lift to slow the XV-5's descent to a survivable rate.
       

      The XV-5A following the second crash.
       
      Following the crash of the second XV-5A airframe, it was decided to rebuild it into the XV-5B, and continue the test program with that aircraft. Numerous improvements were made to the systems of the XV-5 (including improved control systems and cockpit layout), correcting some of the deficiencies of the XV-5A. The aircraft was also repainted in NASA colors (the XV-5A had been painted in US Army markings.)
      i
      http://aviadejavu.ru/Images6/MY/MY77-6/10-3.jpg
       
      In addition to being used for testing of the VTOL characteristics and the lift-fan concept, the XV-5B was used for testing of approach procedures for VTOL aircraft. Particularly, the XV-5B was flown at steep approach angles of up to 20 degrees.The aircraft was flown successfully in this role, but it was found to be somewhat difficult for the pilot, as engine throttle, lift fan controls, and conventional flight controls all had to be manipulated to stabilize that approach. Testing of the XV-5B in this role was continued until 1971, when the aircraft was retired. It is currently on display in Fort Rucker, Alabama.
       

      http://cdn-www.airliners.net/aviation-photos/photos/7/1/7/2287717.jpg
       
      Video footage of the XV-5A
       

       
       
       
       
      Sources:
       
      PRELIMINARY PILOT QUALITATIVE EVALUATION OF THE XV-5A RESEARCH AIRCRAFT
      Lift Fan Aircraft - Lessons from Pilot's Perspective
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