Pre-war aircraft - ID please

[LT Ducky]

From the Life-Google topic in the FFZ

 

 

http://images.google.com/hosted/life/f?q=b...538be76e5f248f7

 

 

What is it -I've never seen it before

[Bob B]

Curtiss A-18 Shrike II:

 

http://en.wikipedia.org/wiki/A-18_Shrike

Edited November 24, 2008 by Bob B

[LT Ducky]

Thanks!

[Guest JamesG123]

That looks like French or some other European paint scheme. Were A-18s ever sold or lend/leased to anyone?

[Shortround6]

Americans were experimenting with camouflage schemes in the late 30s-into 1940-41 especially in annual war games.

 

Note the device under the wing. Possiably a smoke screen dispenser. Americans were also experimenting with aircraft laid smoke screens as part of the land battle. this might have required the cooperation of the enemy---like a lack of AA fire;-)

[MiloMorai]

James, some pre 1940 American a/c had such paint schemes.

[DKTanker]

Here's a sweet looking aircraft.

 

[shep854]

Except for a twin-tail, Ducky's original picture also closely resembles the Beech XA-38 Grizzly http://en.wikipedia.org/wiki/XA-38_Grizzly

[gewing]

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QUOTE(Bob B @ Mon 24 Nov 2008 1250) 621338[/snapback]

Curtiss A-18 Shrike II:

 

http://en.wikipedia.org/wiki/A-18_Shrike

 

 

 

I wonder what the A-18 would have done with larger engines?

 

Could it have worked for an early US analogue to the Tigercat or Hornet? I am still thinking about a hypothetical "fighter-bomber" or zerstorer analog, I guess.

 

Converted to a single pilot plane, 1000-1200 HP engines, 4-6 forward .50 caliber guns and provisions for bombs, rockets, or a torpedo??

 

later fitted with 2x 37mm guns for ground attack?

 

I had thought to start from the F5F, rapidly converting it to something closer to the XP50, but the A-18 might be a more practical basis...

 

Or I could be completely off base!

[Timo]

Here's a sweet looking aircraft.

 

 

Oh my, that is one sexy bird. The tiny forward cross section would imply that it would have been a hard target for Flak (or that it's a HUGE aircraft in general). Give that some serius concentric nose armament and let's go strafin'

 

EDIT: mmkay, so it had 6x37mm planned already. Maybe 8-10 Hispanos would have been better?

Edited November 28, 2008 by Timo

[Marek Tucan]

EDIT: mmkay, so it had 6x37mm planned already. Maybe 8-10 Hispanos would have been better?

 

Modular armament? Battery of Hispanos or 57mm Mollins gun?

[shep854]

Check the Wiki link I posted on the Beech Grizzly: it was designed around a 75mm cannon--kind of a philosophical grandparent of the A-10.

[Geoff Winnington-Ball]

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QUOTE(Bob B @ Mon 24 Nov 2008 1550) 621338[/snapback]

Curtiss A-18 Shrike II:

 

http://en.wikipedia.org/wiki/A-18_Shrike

 

Put a couple of Merlins in that thing and I bet it would go like a sumbitch...

[Shortround6]

Gewing:

"I wonder what the A-18 would have done with larger engines?"

 

"Or I could be completely off base!"

 

I am afraid you might be. The pace of circraft development in the the 1930's was frantic, only a few years seperated generations of aircraft.

The predicessor of the A-18 first flew in 1935 so pencil to paper may have started in 1933-34. The A-18 was a large airplane. It's wing is only about 2 feet less in span than a A-20s and has more area. First A-20 flew in Jan 1938. While hanging later model Cyclone engines on the airframe of the A-18 wouldn't be too big a problem from a weight or size standpoint the question is wether the airframe is strong enough to handle the extra power and speed. Once you start beefing up the existing airframe to any great extent you might just be better off with a new airframe. An airframe stessed to X number of "G"s at 12,000lbs is only good for about 80% of the"G"s at 15,000lbs. Once the war has started you are kind of stuck with airframes in production but the US in the very late thirties would have been making a mistake not to go with a newer airframe using more modern (even if only by two or three years) airfoils, flap arangements, structural analysis and such.

 

As for a pair of Merlins, the A-18 had about 5ft more wingspan (10%) and 72 sq ft more wing area (15%) while weighing about 6000lbs less empty than a Mosquito, one does have to wonder about the structual strength of the A-18 to handle large increases in engine power and payload;)

[gewing]

Oh my, that is one sexy bird. The tiny forward cross section would imply that it would have been a hard target for Flak (or that it's a HUGE aircraft in general). Give that some serius concentric nose armament and let's go strafin'

 

EDIT: mmkay, so it had 6x37mm planned already. Maybe 8-10 Hispanos would have been better?

 

 

 

I have always thought it looked like it should have been jet propelled from the beginning!

 

Wasn't another option something like 4 or 6 75mm guns? Assuming they worked, of course.

[DKTanker]

I have always thought it looked like it should have been jet propelled from the beginning!

What I find astonishing is how long it took before the blended wing/fuselage was seen on production aircraft.

[gewing]

What I find astonishing is how long it took before the blended wing/fuselage was seen on production aircraft.

 

 

 

I assume (you know what that means! ) that it was much more difficult/expensive to do reliably. A prototype that is almost a sculpture is probably relatively easy...

 

I have wondered whether blending the wing/fuselage and wing/nacelle junctures on planes like the P-38 or the Hornet could have allowed increased internal fuel storage, possibly with less total drag?

[gewing]

Gewing:

"I wonder what the A-18 would have done with larger engines?"

 

"Or I could be completely off base!"

 

I am afraid you might be. The pace of circraft development in the the 1930's was frantic, only a few years seperated generations of aircraft.

The predicessor of the A-18 first flew in 1935 so pencil to paper may have started in 1933-34. The A-18 was a large airplane. It's wing is only about 2 feet less in span than a A-20s and has more area. First A-20 flew in Jan 1938. While hanging later model Cyclone engines on the airframe of the A-18 wouldn't be too big a problem from a weight or size standpoint the question is wether the airframe is strong enough to handle the extra power and speed. Once you start beefing up the existing airframe to any great extent you might just be better off with a new airframe. An airframe stessed to X number of "G"s at 12,000lbs is only good for about 80% of the"G"s at 15,000lbs. Once the war has started you are kind of stuck with airframes in production but the US in the very late thirties would have been making a mistake not to go with a newer airframe using more modern (even if only by two or three years) airfoils, flap arangements, structural analysis and such.

 

As for a pair of Merlins, the A-18 had about 5ft more wingspan (10%) and 72 sq ft more wing area (15%) while weighing about 6000lbs less empty than a Mosquito, one does have to wonder about the structual strength of the A-18 to handle large increases in engine power and payload;)

 

 

I was wondering whether 1000 or maybe even 1200 hp engines would have enabled it to develop into a roughly 300 mph bomber/attack/torpedo? aircraft with which the US could start the war.

 

just thoughts for alternate Foresight America type stories.

 

The basic A-18 was a little less than 2/3 the weight of the A20. I don't know enough about design to know whether that would have made it enough cheaper to be worth much. It looks like it might have been bigger than the Whirlwind, but smaller than any of the other twin engine competitors I found in a quick look around.

 

A 300 mph attack aircraft in 1937 or 38?

[Shortround6]

I am certainly not an expert in aircaft design but I think the A-18 was just too old and too big to compete with later types of aircraft. While it might have been possiable to get 300mph from it with big enough engines the forces acting on the wings go up with the square of the speed. I am not saying the wings would tear off but the safety margin does go down and while not every part of the wing would have to be made heavier there might be some increase in weight.

 

The A-18 wasn't really all that small, try comparing it to the Bristol Blenheim or even the Martin B-10 bomber (an interesting comparision because they used basicly the same engines) . As far as later aircraft go try even the Martin Maryland.

 

http://en.wikipedia.org/wiki/Martin_Maryland

 

 

I don't know why the A-18's wing was so big. Perhaps there was a landing speed requirment or a requirement for take-off to 50ft within a certain distance? I do note that the first prototype was not fitted with a constant speed propellor which would improve take-off performance drasticly. I would further note that not only is the A-18 of an age to place it against the Bristol but it is also a contemperary of the Armstrong Whitworth Whitley, a much larger aircraft to be sure but one that was initially designed without flaps. The early-mid thirties mark the change over from fabric covered biplanes to all metal monoplanes. Or to put it another way, they were changing over from flying on large wings and low power to small wings and high power.

 

Try comparing wing sizes to even the Ju 88 or the Dornier Do 17. The A-18 was light but it wasn't small.

[Bob B]

Another aircraft of that era which was close in size to the A-18, was the Italian Breda Ba.88. This nice looking twin engine attack plane broke several speed records as a prototype, but once all the military equipment was hung on it it barely had the power to get off the ground, and there are some recorded instances where they couldn't get airborne with with a combat load. The Italians tried to lighten it by stripping out equipment, and leaving the rear gunner at home , but this didn't really improve things.

 

These failings were evident and known before production was started, but it was a political decision made to keep the plants producing that caused their production to continue. They ended up being used as decoy's on Italian airfields. It would have been better if they had been canceled when the faults were discovered, and the effort and material put to better use.

 

http://en.wikipedia.org/wiki/Breda_Ba.88

 

According to the A-18's Wiki article, it only carried a 400 lbs bomb load in two wing bays with another 200 lbs under the wings. Those must have been small bombs compared to what the other current dive bombers, and attack planes were hauling.

 

I can't help but think that If the A-18 did continue on in a modified form it might have suffered a similar fate to the Ba.88. Instead it finished it days with training units, while Uncle Sam's aircraft plants went on with newer designs.

Edited December 1, 2008 by Bob B

[gewing]

I am certainly not an expert in aircaft design but I think the A-18 was just too old and too big to compete with later types of aircraft. While it might have been possiable to get 300mph from it with big enough engines the forces acting on the wings go up with the square of the speed. I am not saying the wings would tear off but the safety margin does go down and while not every part of the wing would have to be made heavier there might be some increase in weight.

 

The A-18 wasn't really all that small, try comparing it to the Bristol Blenheim or even the Martin B-10 bomber (an interesting comparision because they used basicly the same engines) . As far as later aircraft go try even the Martin Maryland.

 

http://en.wikipedia.org/wiki/Martin_Maryland

I don't know why the A-18's wing was so big. Perhaps there was a landing speed requirment or a requirement for take-off to 50ft within a certain distance? I do note that the first prototype was not fitted with a constant speed propellor which would improve take-off performance drasticly. I would further note that not only is the A-18 of an age to place it against the Bristol but it is also a contemperary of the Armstrong Whitworth Whitley, a much larger aircraft to be sure but one that was initially designed without flaps. The early-mid thirties mark the change over from fabric covered biplanes to all metal monoplanes. Or to put it another way, they were changing over from flying on large wings and low power to small wings and high power.

 

Try comparing wing sizes to even the Ju 88 or the Dornier Do 17. The A-18 was light but it wasn't small.

 

 

 

The maryland doesn't look any sleeker, has slightly larger wing area, is a bit larger and heavier (not much)----

Is it due to the 1250 hp instead of 850 hp engines that it is so much faster?

 

I do realize the idea of an evolved shrike is questionable, but It just seemed like an interesting what if for an early twin attack aircraft.

[Shortround6]

I would say that having the more powerful engines does help the Marland quite abit. The A-18 does have a sleek looking fuselage but may be let down by the wings, engine nacelles and other bits and pieces. By the time the wing is redesigned, more powerful engines fitted and the whole aircraft restressed to handle more weight (double or triple the bomb load, 50-100% more fuel, even a minimal amount of armour, any change from the FIVE .30 cal MGs the A-18 had) you might as well base your plane on a newer airframe to begin with.

 

Which is pretty much what the Air corp did, calling for the design competition that resulted in the DB-7 which lead to the A-20, the Martin Maryland and the NA-40 which lead to the B-25. THis was in 1938.

By March of 1939 the AAF was interested in even newer planes which lead to the B-26 being ordered off the drawing board with the first one flying November 25th 1940, just after the Battle of Britian and ONE FULL year before Pearl Harbor. Now it does take time to ramp up production and get into squadron service. I don't know what your proposed time line is but there may be time to come up with a newer plane than the A-18 before America has to use it.

 

Try comparing the A-18 to the Messerschmitt bf 110 which seems to be 1-2 years later in timing.

 

If you really want a torpedo plane you are going to need a base plane that could carry 1600-2000lb bomb load. Likewise if you want a big gun tank buster.

 

Wonder what a Maryland would look like with a pointy nose and that step/lower gun position taken out of the fuselage;)

 

I would also note the Americans jumped right over the twin 1200hp attack plane/bomber and went for the twin 1600hp attack plane/bomber.

[hojutsuka]

What I find astonishing is how long it took before the blended wing/fuselage was seen on production aircraft.

Not that surprising, IMHO. Most aircraft designers try to achieve their performance goals at least cost and least risk.

 

The F-16 was one of the first production aircraft to be designed with blended wing/body. IIRC, in the discussion back then, GD engineers claimed that:

 

1. The blended wing/body allowed the wing spar to be very deep at the fuselage juncture. This allowed the wing structure to be strong yet lighter.

2. The blended wing/body provided extra volume, so that the aircraft could hold the required amount of fuel in an airframe of smaller overall dimension.

 

So by using blended wing/body, the F-16 ended up being smaller and lighter.

 

Now, let us look at these advantages in terms of World War II aircraft.

 

1. WW II aircraft flew a lot slower, about half the maximum speed of F-16 at best.

 

Slower speed meant that WW II wing profiles could be deeper (higher thickness/chord ratio), i.e. you get most of the benefits of deep spar without having to resort to major wing/body blending.

 

Slower speed means much lower aerodynamic loads. Typically aerodynamic load goes up by square of speed, so the F-16 has to take about 4 times the aerodynamic load of a WW II aircraft. The lower load on WW II aircraft means that an adequately strong wing spar/fuselage junction could be built without resorting to blended wing/body or incurring a weight penalty.

 

2. WW II aircraft were almost all powered by piston engines.

 

Piston engines use a lot less fuel than jet engines. So you needed a lot less space for the fuel (if you look at a cutaway drawing of a WW II fighter, there is typically a lot of empty space, especially in the rear fuselage. An F-16 in contrast has has something stuffed in every usable space). Plus, the thicker wing made possible by lower speed allowed WW II aircraft to carry more fuel in their wings. So a WW II aircraft did not really need the extra volume generated by blended wing/body.

 

So for a WW II aircraft, the advantages of blended wing/body are minimal. But what are its disadvantages?

 

A. As gewing has pointed out, a blended wing/body is difficult and expensive to build using WW II technology.

 

If you look at the McDonnell XP-67, much of its skin has compound curvature (it is curved along more than one axis). Compound curvature is much more difficult and expensive to manufacture using WW II technology.

 

B. Blended wing/body makes for complicated aerodynamics, probably beyond the state of the art in WW II.

 

A wing with little or no sweepback can be modeled two dimensionally, because the airflow can be assumed to be parallel to the wing chord. But a blended wing/body inevitably means that there is a section of wing close to the body with very large sweepback. This, plus the very large and rapid change in wing section as you go outwards from the wing/fuselage junction makes for a rather complicated dynamics, beyond the state of WW II aerodynamic theories and practices. When jet aircraft with swept back wings became the norm after WW II, many of the earlier ones had major handling problems. It took the aerodynamicists years of hard work and experience to learn to deal with this. If you look closely at a modern fighter wing it is a very complex piece of design, typically with wing section changing continually from wing root to wing tip, varying amount of washout, possibly conical camber on the leading edge, et cetera. We can do this today because the theory has advanced, and also because we have supercomputers to run computational fluid dynamics codes, but there is no way in WW II to design such a wing.

 

So in WW II blended wing/body offered little advantage but major drawbacks. IMHO, it is reasonable that the first production blended wing/body design appears in the '70s, because that was when such a design became feasible and useful.

 

Hojutsuka

 

Spelling edit.

Edited December 3, 2008 by hojutsuka

[gewing]

My goal in an alternate timeline would basically be to have a 300+ mph "attack Fighter" in squadron service before Pearl Harbor. I was thinking maybe pilot and observer/navigator, or single pilot.

 

I would prefer it to have the capability to grow further... So for instance if It could carry for Instance 6 x.50 caliber, and one aerial torpedo on 2x1000 hp engines, there would be growth capabilty as 1200 hp and larger engines became more available.

 

The initial version might have 2000lb bomb capacity as an alternate payload. If I had my druthers, at least most of the guns would be in a pallet that could be removed and replaced by cameras or different guns. I would like to see the torpedo and or bombs in at least a semi-conformal carry, for reduced drag. A full internal bomb bay would probably be beyond the scope of the concept.

 

By say mid 42, a version with 2x 1250 hpr engines, 3x20mm cannons and 2x .50 caliber (Of course, 4x 20mm would be acceptable ...), and either one torpedo, two "Tiny Tim" analogue rockets, or comparable bomb load should be coming along.

 

I should get back to those doodles I was working on, now where did I put my "Janes fighting aircraft of WWII?"

 

 

As to blending the wing, body, and nacelles, I have been wondering whether enough could be done with fiberglass to reduce the overall drag on the aircraft.

 

though I still wonder about a lifting body center section between nacelles, housing cockpit, weaponry, and significant fuel...

Edited December 4, 2008 by gewing

[Shortround6]

"As to blending the wing, body, and nacelles, I have been wondering whether enough could be done with fiberglass to reduce the overall drag on the aircraft. "

 

Fiberglass, as we know it, didn't come into existance until some time during the war. Glass fiber (without the plastic resin, like insulation) wasn't really around until 1938.

 

Another point is at what point the reduction of eddys and form streamlining outweigh increased surface drag. Large wing root fillets were common for streamling although a 90 degree interface between wing and fuselage could do very well without them. See Grumman midwing fighters or the Corsair.

 

"though I still wonder about a lifting body center section between nacelles, housing cockpit, weaponry, and significant fuel..."

 

do you mean like this:

 

http://www.aircrash.org/burnelli/ch_cby3.htm

 

or this:

 

http://www.aircrash.org/burnelli/ch_oa1.htm

 

http://www.aircrash.org/burnelli/ch_ub14.htm

 

A part of your problem is the intended range of the aircraft. While you might be able to make a plane in 1938-40 with twin 1000hp engines that could break 300mph while carrying Six .50s and yet still carry a torpedo at a slower speed, the resulting aircraft might not have a very large range. Carrying that weapons load plus a large amount of fuel might require a larger plane than a pure "fighter" type. The larger airframe might have too much drag to get the top speed you want.

 

Note that by the time the british hung a torpedo under a Beaufighter it had engines of about 1700hp. Granted it is a bit larger than you are proposing and may have had a much longer range than you need.

try looking at the Blackburn Firebrand torpedo stike fighter. Single seat, single engine, 4 20mm guns, 2,200hp or more. 51ft wingspan, 381 sq ft of wing area.

Or look at a Grumman Avenger. 1700hp, 330 gallons of fuel in wing tanks alone. granted it has 3 seats and that heavy turret but it's forward firing armament is 1/6 what you are proposing.

And a twin is never as efficient as a single of equel power. A 300mph + aircraft carring a torpedo is not impossiable in that time frame using 1000-1100hp engines. having the same aircraft try to double as a fighter maynot work. or try to double as a heavy duty straffer after dropping the torpedo. Again it may depend on range.

 

Many B-25s and B-26s were equiped to carry torpedos even though they seldom (if ever) did.

By 1942 the US would be making aircraft with 1700hp engines or larger rather than fooling around with 1350Hp engines unless forced to by aircraft design (Like P-38). See http://en.wikipedia.org/wiki/Lockheed_B-34