Douglas XA2D-1 Skyshark

[hesham]

Hi,

from Flightglobal the developments of Douglas Skyshark.


http://www.flightglobal.com/pdfarchive/view/1950/1950%20-%201928.html

 

[frank]

Looks like SkyRAIDER developments, leading to the SkySHARK.

 

[Antonio]

Many thanks hesham, great discover again. I've read about that but never saw the drawings before

 

[Triton]

The Douglas XA2D-1 Skyshark was a turboprop-powered attack aircraft built by the Douglas Aircraft Company for the United States Navy. The requirement to operate from Casablanca-class escort carriers dictated the use of a turboprop instead of jet power. The aircraft first flew on May 26, 1950.

Unfortunately, the Skyshark had an "Achilles heel," that being the main bearing of the Allison engine, which was basically two J-40 turbojets linked by this main bearing to provide power to the contra-rotating propellers. Allison seemed unable to overcome the problem.

http://en.wikipedia.org/wiki/A2D_Skyshark
http://modelingmadness.com/reviews/korean/cleavera2d.htm
http://home.att.net/~jbaugher4/a2d.html


Photographs of Douglas XA2D-1 Skyshark.

 

[Stargazer]

Thanks! Great pics of a fascinating bird... Here's my contribution to the thread:

 

[Tailspin Turtle]

Unfortunately, the Skyshark had an "Achilles heel," that being the main bearing of the Allison engine, which was basically two J-40 turbojets linked by this main bearing to provide power to the contra-rotating propellers. Allison seemed unable to overcome the problem.

The engine was a T40 turboprop, which was comprised of two XT-38 turboprop power sections, not J40 turbojets (which was another and even bigger disappointment). The link was a combining gearbox that wasn't quite up to the power going into it. The T40 also contributed to the failure of the A2J program but can't really be blamed for the FY/FV's lack of success. Some R3Ys seaplane transports were built and put into service but after incidents caused by engine failures, they were grounded as well.

 

[Triton]

General characteristics

* Crew: 1
* Length: 41 ft 3 in (12.58 m)
* Wingspan: 50 ft 0 in (15.24 m)
* Height: 17 ft 1 in (3.68 m)
* Wing area: 400 ft² (37 m²)
* Empty weight: 12,900 lb (5,864 kg)
* Loaded weight: 18,700 lb (8,500 kg)
* Max takeoff weight: 22,960 lb (10,436 kg)
* Powerplant: 1× Allison XT-40-A-2 turboprop, 5,100 shp (3,800 kW)

Performance

* Maximum speed: 435 kn (501 mph, 813 km/h)
* Range: 1,900 nmi (2,200 mi, 3,520 km)
* Service ceiling: 48,100 ft (14,664 m)
* Rate of climb: 7,290 ft/min (37 m/s)
* Wing loading: 47 lb/ft² (230 kg/m²)
* Power/mass: 0.27 hp/lb (440 W/kg)

Armament

* Guns: * 4 × 20 mm (0.79 in) T31 cannon
* Other: 5,500 lb (2,500 kg) on 11 external hardpoints

 

[Orionblamblam]

But Wait! There's More!

 

[Stargazer]

Oh wow. OBB has come up with another killer blueprint! Looks like the son of a Skyshark and a Skyknight...

 

[elmayerle]

Unfortunately, the Skyshark had an "Achilles heel," that being the main bearing of the Allison engine, which was basically two J-40 turbojets linked by this main bearing to provide power to the contra-rotating propellers. Allison seemed unable to overcome the problem.

The engine was a T40 turboprop, which was comprised of two XT-38 turboprop power sections, not J40 turbojets (which was another and even bigger disappointment). The link was a combining gearbox that wasn't quite up to the power going into it. The T40 also contributed to the failure of the A2J program but can't really be blamed for the FY/FV's lack of success. Some R3Ys seaplane transports were built and put into service but after incidents caused by engine failures, they were grounded as well.

The T56 developed out of the problems with the XT38 and did well. I get the impression the US armed services were not at all confident that Allison had resolved the problems with the XT40's gearbox, since the equivalent T54, using two T56 power sections does not appear to have made it to the "metal cutting" stage.

 

[Tailspin Turtle]

But Wait! There's More!

Excellent! And sort of explains this:

 

[airman]

a son of Douglas Skyraider !

 

[Tailspin Turtle]

I hadn't heard of the Westinghouse X25D2 turboprop and in Googling it, discovered a 1946 Aircraft Power Plants report that I wasn't aware of before:

http://www.governmentattic.org/vonK/AcftPwrPlants_VKarman_V6.pdf

The X25D2 engine was projected to provide 3,300 horsepower and 980 lbs of thrust at sea level, 0 knots.

 

[Stargazer]

X25D2 was an inhouse designation at Westinghouse. It could very well have been the DoD designated T54 or a variant of the T40. Can anyone confirm that?

 

[elmayerle]

X25D2 was an inhouse designation at Westinghouse. It could very well have been the DoD designated T54 or a variant of the T40. Can anyone confirm that?

I'd say it's unlikely since both the XT40 and the T54 were Allison products.

 

[Stargazer]

ARGH! I can be so idiotic at times reading too fast... :-[

Of COURSE it is Allison... The plagued T40... The Westinghouse turbine may have received a designation in the same range of numbers, but I don't have them all in my list (T41 to T48, T52 and T56 are missing).

 

[elmayerle]

Well, http://www.designation-systems.net/usmilav/engines.html can probably fill in some holes. A very useful set of engine listings.

 

[Stargazer]

Gosh! I didn't remember that Andreas' site had ALSO the engines... There's stuff there that complements my own lists... but I also have sub-variants that I think are missing there, so I'll double check and write Andreas about it some time. Thanks for reminding me!

 

[Triton]

Additional photographs and line drawings of Douglas XA2D-1 Skyshark.

 

[Abraham Gubler]

Why doesn't someone put a T56 in this and bid it for the USAF light attack (OA-X) requirement? A Sandy for 21st century wars...

 

[Triton]

Allyn model of Douglas A2D-1 Skyshark.

 

[Stargazer]

The logo... (from Ginter's NAVAL FIGHTERS #43 cover)

 

[Jos Heyman]

The A2D evolved from the BT3D studies and two examples of the XA2D-1, which were temporarily designated as AD-3, were ordered on 25 September 1947 with serials 122988/122989. The first flight took place on 26 May 1950. The engine consisted of two coupled XT38 engines which drove a common gear box. The second aircraft was later re-engined with a XT40-A-6 engine.
Production of 349 A2D-1 production aircraft was ordered but eventually only 6 with serials 125479/125484 were built. The remainder, with serials 125485/125488, 127962/128042, 132793/133042 and 134438/134445, were cancelled, although 125485/125488 were completed. The cancellation of the programme was due to the difficulties encountered with the coupled engines as well as the advent of the A4D jet aircraft.

 

[Stargazer]

More great stuff from the Ginter Naval Fighters book, an absolute must have packed with diagrams, plans and photos!

 

[Stargazer]

... and also the sole surviving A2D as it appeared in the 1960s. Quite a different looking bird without the props and with the different color scheme...

 

[CFE]

It would be interesting to see if anything would have come from the Skyshark had a more reliable powerplant in the same performance class been available (the T56-A425 of the E-2 Hawkeye comes to mind.) But the Skyshark is a conspicuous example of a technical development that was overcome by events. By the time the Skyshark was flying, Ed Heinemann and co. had secured approval for an aircraft that was the antithesis of the Skyshark's complexity: the A4D Skyhawk. The A4D's simplicity, superior speed, and nuclear weapons capability sealed the fate of the intriguing Skyshark.

 

[elmayerle]

... and also the sole surviving A2D as it appeared in the 1960s. Quite a different looking bird without the props and with the different color scheme...

IF I'm not mistaken,hasn't the prop spinner been replaced by the nose of a Skyhawk?

 

[saturncanuck]

Unfortunately, the Skyshark had an "Achilles heel," that being the main bearing of the Allison engine, which was basically two J-40 turbojets linked by this main bearing to provide power to the contra-rotating propellers. Allison seemed unable to overcome the problem.

The engine was a T40 turboprop, which was comprised of two XT-38 turboprop power sections, not J40 turbojets (which was another and even bigger disappointment). The link was a combining gearbox that wasn't quite up to the power going into it. The T40 also contributed to the failure of the A2J program but can't really be blamed for the FY/FV's lack of success. Some R3Ys seaplane transports were built and put into service but after incidents caused by engine failures, they were grounded as well.

In my research I have yet to find ANY aircraft that was successful with the T40.

It seems that as soon as they assinged the engine to an aircraft, it was doomed.

 

[Stargazer]

Absolutely right. The T40 was plagued and every aircraft that had the misfortune to be associated with it had its doom sealed from the start... The number "40" must have been something of a jinx because the J40 turbojet didn't fare much better either...

 

[Steve Pace]

Corky Meyer - the only person to fly the J40-powered XF10F-1 Jaguar, said the airplane "could barely get out of its own way."

 

[elmayerle]

Corky Meyer - the only person to fly the J40-powered XF10F-1 Jaguar, said the airplane "could barely get out of its own way."

*wry chuckle* I once drove a rental car like that, a 1976 Mercury Bobcat MPG with an automatic transmission; if floored, it might get out of its own way.

 

[Justo Miranda]

Some additional info -Post-1

 

[Justo Miranda]

Some additional info -Post-2

 

[Justo Miranda]

Some additional info -Post-3

 

[Stargazer]

Wow! All great material. Thanks for the scans!

 

[saturncanuck]

Absolutely right. The T40 was plagued and every aircraft that had the misfortune to be associated with it had its doom sealed from the start... The number "40" must have been something of a jinx because the J40 turbojet didn't fare much better either...

A lot ot "paired" or "twinned" engines and aircraft never did well.

Remember the He 177?

 

[Jemiba]

At least the Fairey Gannet with its Bristol Siddeley Double Mamba
could be regarded as a proof, that it isn't the basic concept, that
is flawed.

 

[AeroFranz]

there are scores of PT6T 'twinpacks' that work pretty well too

 

[airman]

Yes, i remember , : the genealogy of Skyraider and than Skyshark, had started with Northrop BT1 ( source Aerei - Delta Editrice - i am not remember year and month )

 

[hesham]

Hi,

the XA2D-1 Skyshark developments;

http://www.secretprojects.co.uk/forum/index.php/topic,4197.0/highlight,skyshark.html