ADO-12 to "US-FRG" AVS V/STOL Fighter Programs

[overscan (PaulMM)]

What appears to be a 1965 Republic Aircraft Corporation (later, Fairchild) FX study. It has no similarity to the final Fairchild FX design above except for the vertical fin, but rather shows some similarities to the AVS designs.

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[overscan (PaulMM)]

Wind tunnel models of a later (1967) iteration of AVS. Similar to the model posted by Circle-5 earlier in this topic:

http://crgis.ndc.nasa.gov/historic/...d_Continuous-Flow_Hypersonic_Tunnels_4#US_FRG

 

[iverson]

What was the logic of combining lift engines and variable geometry wings? Was this just a combination of the design fads of the era? Or was there some logic to it? To me it seems like two fundamentally opposed approaches to the same requirement.

Variable geometry is an aerodynamic approach. It lets you combine a wide-span, high-lift wing for STOL operations with a highly swept wing for low gust response at low levels and high speeds. The wing is complex and heavy, but the power-plant arrangements are fairly simple and the required thrust is modest.

Lift engines rely on thrust to achieve what the VG design does with aerodynamics. Lift engines allow VTOL, so you can dispense with the large wing altogether and have a stiff, light, short-span unit. But the power-plant arrangment is heavy and complex, and you need more thrust to get off the ground than you can use in flight.

Combining the two approaches thus appears to make no sense (except on the contractor's bottom line, no doubt). If you choose the STOL solution, you do not need the extra weight penalty and complexity of VTOL. If you choose VTOL, you do not need the extra weight penatly and complexity of STOL.

 

[overscan (PaulMM)]

VG was considered (for a short time) the universal panacea, combining good high speed and low speed handling in one wing design. The weight and complexity implications were not clear at the time. VTOL was also in vogue and its weight penalties also not fully understood.

A bit later, LERX were all the rage, until canards became next season's "must have" accessory.

Don't forget as well that in practise Harriers operated in STOVL mode - I would think a VG wing in unswept configuration would help immensely in ultra short takeoffs assisted by thrust vectoring, while the engine would allow a vertical landing at lighter weights.

 

[circle-5]

Behold the Sabre V/S attack bomber by North American Aviation. This concept was based on the Bristol Siddeley Pegasus vectoring thrust engine (used in the Harrier) and had nothing in common with the F-86 or F-100, except the name.

The Sabre V/S could carry two gravity bombs internally. These were placed at the CG of the aircraft, just outside the center of thrust, which explains the very wide fuselage. Four additional turbojets were used during vertical flight.

These four lift jets were lined-up horizontally, facing backwards inside the rear section and fed via a louvered, top intake. Hot gases would be combined in pairs and ducted forward toward the CG where they would elbow downward, right between the hot and cold exhausts of the Pegasus.

See cutaway photo for a layout of the Sabre V/S propulsion arrangement: red means hot, while green is cold. The concentrated exhaust of five jet engines into such a small area means the aircraft could probably clear its own landing site just about anywhere...

Presumably, the Sabre V/S could also park itself directly above a target to drop its bombs (while the enemy politely refrained from shooting at it). This would certainly simplify aiming and targeting tasks ;D.

 

[Steve Pace]

I wonder what the NA number is?... -SP

 

[circle-5]

I wonder what the NA number is?... -SP

Dunno. I was hoping you could tell me!

 

[Orionblamblam]

I've never seen this before, but that won't stop me pontificating... I'd bet that this was a contemporary of the Republic-Fokker D-24 Alliance.

 

[Stargazer]

What a beautiful design!! Very nice find, circle-5!

 

[overscan (PaulMM)]

Can't find anything useful.

North American Aviation received Pegasus brochures from the very start of the program (1957 onwards) but there doesn't seem to have been any significant contact with Bristol about it, so it seems unlikely to have gone very far in design.

Like Scott said, could be a D-24 Alliance type design, but I would expect mandatory VG wings by that stage.

One possibility would be circa 1958-59 GOR. 169 study. Most likely it never proceeded past an RD- designation.

 

[LowObservable]

Wow.

It looks like something designed in the early NATO VSTOL days (cf VAK 191, early G.95 studies) when the basic mission was 0.92/sea level/250 nm instant sunshine delivery.

I wonder if Boeing had seen the weapons arrangement when they did the X-32 design....

 

[vstol]

Wow - now that's different!

 

[circle-5]

Underside view of the Sabre V/S model. Red rectangles represent the hot exhaust from each pair of lift engines.

 

[Steve Pace]

Is it just me or does this design have a bit too much canopy -SP

 

[Jemiba]

Is it just me or does this design have a bit too much canopy -SP

reminds me on tandem seat version of the Marchetti MI-600.

http://www.secretprojects.co.uk/forum/index.php/topic,8821.0/highlight,marchetti.html

The cockpit walls may be that low, to allow a better view for vertical landings, i think

 

[Stargazer]

Is it just me or does this design have a bit too much canopy -SP

Not any more than the TAV-8A Harrier did!

 

[Abraham Gubler]

I wonder what the NA number is?... -SP

Unlikely to be one. NAA only assigned NA-x numbers for a specific contract. It was an accounting system not a prototype tracking system. This is why many North American aircraft have multiple NA-x numbers assigned as each one was for the relevant contract (and CAC who copied their internal model). So unless this VSTOL aircraft was in response to a contract rather than an internal study it won’t have a NA-x number.

 

[Abraham Gubler]

Is it just me or does this design have a bit too much canopy -SP

As much glass as is needed to provide the pilot with excellent visibility without using a dreggier teardrop canopy.

 

[Mike Pryce]

Wow! Presumably designed for very short missions, as all the space for fuel is full of engines and ducts.

And two doses of 'instant sunshine', dropped directly into the Pegasus jet flows!

And if you size the canopies from the engine inlets (if it is a Pegasus) then it has way more glass than any Harrier. Maybe a sealed greenhouse for the crew to live in during the post-war big chill?

 

[circle-5]

Please help identify this Boeing airplane. This is not a contest -- I don't know the answer, and there is no prize (but lots of glory...)

Thanks to Chad Slattery for the photos.

 

[Steve Pace]

Please help identify this Boeing airplane. This is not a contest -- I don't know the answer, and there is no prize (but lots of glory...)

Thanks to Chad Slattery for the photos.

Looks like a variation of Boeing's 818 TFX proposal. -SP

 

[uk 75]

It also looks like the us german 60s .A.V.S strike fighter. Nibe model. I love this sort of plane

 

[Matej]

Definitely something around TFX era. I am not sure if the predcessor or the successor.

 

[Antonio]

My vote is for a TFX predecessor

 

[aim9xray]

This is Boeing Model 956 PDII-10 (supersonic variant). The aft engines are afterburning turbofans; the plug nozzles serve as blockers for VTO mode. There are eight small VTO vertically mounted turbojet engines in the fuselage aft of the cockpit - four in the left and four in the right chine (inboard of the the wing glove). Length was 62.5 feet. Gross VTO weight was to be 40000 lbs.

The 956 PDI-10 was the subsonic variant. I'd guess the pair to be AVS competitors or possibly USAF ADO-12 (Advanced Development Objective - 12) study designs circa 1963-4 (ish).

 

[Howedar]

The airframe has a lot of configurational similarity to the 818, which was a response to TFX.

 

[circle-5]

This is Boeing Model 956 PDII-10 (supersonic variant). The aft engines are afterburning turbofans; the plug nozzles serve as blockers for VTO mode. There are eight small VTO vertically mounted turbojet engines in the fuselage aft of the cockpit - four in the left and four in the right chine (inboard of the the wing glove). Length was 62.5 feet. Gross VTO weight was to be 40000 lbs.

The 956 PDI-10 was the subsonic variant. I'd guess the pair to be AVS competitors or possibly USAF ADO-12 (Advanced Development Objective - 12) study designs circa 1963-4 (ish).

Thank you aim9xray! I didn't think this was a VTO design, because of the complete absence of chine scribings for the lift engines, both top and bottom. The main engine plugs and top intakes do make sense, however. And it has enough complexity to qualify as an AVS contender.

So you get the glory, and on Valentine's Day no less!

 

[taildragger]

aim9xray,
What were the nature of the AVS and ADO-12 requirements - interceptor? Model 956 PDII-10 looks to me like a nuclear penetrator. I wouldn't think that a subsonic variant would be offered for anything but an aircraft intended for an attack role. Also, the nose looks a little small for an AI radar of the day.

 

[aim9xray]

You are pretty much correct, at least for the AVS. For further info on AVS, see http://www.secretprojects.co.uk/forum/index.php/topic,452.msg33748.html#msg33748. The design as shown above had a single belly external stores station with 2000 lbs load capability, one option was a nuclear "special store".

As far as ADO-12, I have no information other than the name and a link to another subsonic V/STOL design. Any background data would be appreciated.

 

[aim9xray]

Whoops, my apologies for introducing some extraneous speculation - this was for US/FRG (later AVS), late 1965.

 

[circle-5]

A most reliable source (aim9xray) tells me the NAA Sabre V/S was an alternate point design study for ADO-12 (USAF Advanced Development Objective No.12), dated June, 1964.

 

[uk 75]

A classic nato nuclear strike fighter to replace the f100 super sabre. France had a .Mirage v for thd same job. One for the modelers?

 

[uk 75]

Noted from a German brochure- 60 sub. and supersonic avs studies. Boeing partner 64-6 in studyphase. System def. 67 with Fairchild. 1400 page final report. Vstol .A400 and stol .S400. Latter basis for nkf in 68.

 

[aim9xray]

Mid to late 1960s color 8x10 inch photographs of AVS models found on eBay

 

[Antonio]

Links doesn't work

 

[aim9xray]

Oops! Sorry about that!

Let's try the raw links - cut and paste into your browser:

[links dead - Admin]

 

[Caravellarella]

Dear Boys and Girls, here is a small piece in French on the EWR/Fairchild AVS variable geometry V/STOL "project"; what were they thinking of? The caption states that the pop-out lift engines could be swivelled and used for horizontal flight if the main engines are inoperable......

The piece comes from the 1st July 1967 issue of Aviation Magazine International......

Terry (Caravellarella)

 

[Stargazer]

Its not related to their TFX contender is it?

Probably not a seriously considered TFX, but the deisgn looks right for the approximate era. VTOL was all the rage at the time.

The 1960-61 TFX proposals (Model 156) did NOT involve VTOL, but there is indeed a Model 193 from 1964 described as a "V/STOL fighter project" which seems to be the most likely candidate.

 

[hesham]

I think that it was McDonnell Model-193 V/STOL fighter of 1964.

As I said,very closely to Model-193.

 

[Stargazer]

As I said,very closely to Model-193.

Hence my use of the word "indeed"... :