Aircraft design

[PMN1]

For propellor aircraft what would be the best undercarriage arrangement?

Since a single vertical tail gave the B-24N better performance, would a single large tail have given the Lancaster and Halifax better performance and if so why.

[GregP]

Probably the best undercarriage arrangement in WWII was conventional landing gear (tailwheel) since most of the airstrips were of the unimproved and grass variety.

If long, paved runways were available, then tricycle gear would have been easier and would have resulted in fewer takeoff and landing accidents ... but "ifs" are just that. WWII was fought from dirt strips mostly, so tailwheel gear was probably better for all concerned.


Single tail versus twin tail is an interesting argument.

For a twin, I like the twin tail since the rudders are in the propeller slipstream. A single tail would be OK for a tricycle gear plane, but you need rudder authority in a conventional gear plane at low speeds and high power settings, as in takeoff from a stop.

An airframe needs a certain amount of vertial surrface area to be controllable and slightly more to be optimum. Too much and it as also bad for stability. Whether it is single or twin fins should be decided by other needs.

Single fin has less wetted area for slightly less drag and is lighter. But twin fins are VERY nice in a twin engine, conventional gear aircraft for low-speed control. I'd venture to say that Vmc (minimum single engine control speed for a twin eingine aircraft) is lower with a twin fin arrangement.

The only other caveat might be Naval aircraft carrier ceiling height.

Twin fins on a single engine aircraft has a lower overall height, and so might be OK for a carrier aircraft (see the Loire-Nieuport LN.411 ... it had three fins for a lower fin height). It would be better to have bigger carriers.

[Romantic Technofreak]

I only want to remark that, reading from one of my sources, the B-24D Liberator with double tailfin runs 488 kp and the otherwise nearly identical PB4Y Privateer with single tailfin only 381 kph (huge difference, I don´t know in which height those speeds were measured).

[PMN1]

quote:Originally posted by Romantic Technofreak

I only want to remark that, reading from one of my sources, the B-24D Liberator with double tailfin runs 488 kp and the otherwise nearly identical PB4Y Privateer with single tailfin only 381 kph (huge difference, I don´t know in which height those speeds were measured).


Wasn't the Privateer slightly bigger?

Does anyone have any figures for the single tailed B-24N - all I have ever heard is that it was considerably faster, had more than double the full load weight of climb and much better power of manoeuvre.

[GregP]

I believe the B-24N SIngle Fin had the following specs:

Four Pratt & Whittney R-1830-75 enngines at 1350 hp each
Max speed: 294 mph
Service ceiling 28000 feet
Weight 65000 pounds
Reference: USAF museum

The Standard B-24D was as follows:
Four Pratt & Whittney R-1830-43 or -65 at 1200 hp each
Max speed: 303 mph
Service celiling: 32,900 feet
Reference: Any B-24D spec
Weight: 63980 pound

Wing spand and area was the same for both.

End of the myth of speedier single-fin model!

[GregP]

The PB4Y Privateer had different turrets and armament than the B-24N, and it had different engine cowlings.

However, the main difference was that the PB4Y, as a Navy patrol bomber, spent most of its time at low altitude, and so was not fitted with turbo-superchargers. Since it wasn't, it never got to the heights at which the standard B-24 and the B-24N achieved their maximum speeds.

No boost means low and slow ... instead of high and fast!

[PMN1]

Any guestimates on fuselage length required for a Lancaster with a tricycle undercarriage but keeping the 34ft bomb bay length - assume a retractable turret or H2S blister on the underside.

[ChrisMcD]

Any guestimates on fuselage length required for a Lancaster with a tricycle undercarriage but keeping the 34ft bomb bay length - assume a retractable turret or H2S blister on the underside.

Doesn't seem to have made much of a difference in the length of the Shackleton from Mk2 to Mk 3

http://en.wikipedia.org/wiki/File:Avro_Shackleton.svg

A lot of these changes were made by moving equipment to shift the C of G and I cannot see why they could not have done that with the Lanc.