b17vs b24

[colmbo]

 The B-24 had a huge wet section to the wing and it would burn readily.

If by "wet wing" you mean the wing was used as a fuel tank....that is incorrect.  There were many fuel bladders within the wing.  The fuel leak problem with the B-24 was at the fuel manifold located above the wing in the fuselage.  The leakage problem was caused because the original fuel lines were oval in shape (imagine trying to get a hose clamp to seal around it <G>).  The leaks put a lot of fuel vapor in the airplane...that's why they normally flew with the bomb bay cracked open a bit for ventilation.

[Chalenge]

No when I say 'wet wing' I mean it had ALOT of fuel in the wing and (from memory) I believe the fuel tanks ran from inboard engine to inboard engine and two more tanks between the inner and outer engines. Add to that the fact that the plane just didnt have the armor of the B17 and just wasnt as rugged either AND was prone to fires in places it didnt have extinguishers. The B17s had engine fires almost every flight but they also had methods to extinguish them.

[colmbo]

No when I say 'wet wing' I mean it had ALOT of fuel in the wing and (from memory) I believe the fuel tanks ran from inboard engine to inboard engine and two more tanks between the inner and outer engines. Add to that the fact that the plane just didnt have the armor of the B17 and just wasnt as rugged either AND was prone to fires in places it didnt have extinguishers. The B17s had engine fires almost every flight but they also had methods to extinguish them.

Roger on the wet wingn thing...both of the bombers had a lot of fuel in the wings.  In fact they both carred the same basic fuel load of 27-2800 gallons (with Tokyo tanks).

B-24 had the same extinguishers on the engine that the B-17 did.

The "fuel tanks" on the B-24 are actually a series of fuel cells.  The outboard "Tokyo tanks" were 9 cells each IIRC.  (My systems book is packed away the the moment)

[Stoney]

When I was flying the -24 and -17 for the Collings Foundation the B-24 would do about 170-180 IAS at 30" and 2000 RPM.   The B-17 at that power setting would be doing about 160-170.

The airplanes carried the same amount of fuel, they burned fuel at the same rate but due to the higher speed of the B-24 it had a considerably longer range.

What was the difference in landing speeds?  I imagine that the B-24 was a good bit faster on landing.

[colmbo]

What was the difference in landing speeds?  I imagine that the B-24 was a good bit faster on landing.

Not really.  We used 120mph on final for both of them.  The big difference is on takeoff.  The B-17 is up and away with little effort.  The B-24 climbs like a pig at first, the gear produce a LOT of drag. The hydraulic system is such that you can raise the gear or the flaps, but not both at once...well you can, but it's going to take a very long time for them to come up.  Normal retraction time for the gear on the B-24 is about 17 seconds...and that can be a long time if you lose an engine early.

[Stoney]

Given the large difference in wing area, with the same loaded weight, I would assume the B-17 was much more docile than the B-24.  Its also why the B-24 was a good bit faster, and probably why its higher altitude performance suffered.  

I'm sure the book values probably differ, but you guys used 120mph to be on the safe side?

[colmbo]

 

I'm sure the book values probably differ, but you guys used 120mph to be on the safe side?

The Army manual for the B-17 shows a 95mph approach speed for a short field landing so we had some margin built into the numbers.  We also had a minimum runway length of 4000'.

The B-24 stalls down around 85 mph.  We don't do stalls in it...they are a bit exciting. <G>  For training we slow to the buffet.  Some of the guys early on stalled the airplane, it has a pretty nasty aileron buffet that can yank the yoke out of your hand if you're not expecting it, all that banging around isn't good for the airplane.

Both of them are unforgiving of aileron use at the stall.  If you try to pick a wing up using aileron you'll roll sharply toward the low wing...as one of the long time bombers said about the B-17 when we were doing approaches to stalls..."If you use aileron to pick up the wing we'll be upside down".   He also advised not to roll the Fortress. <G>

[Stoney]

The Army manual for the B-17 shows a 95mph approach speed for a short field landing so we had some margin built into the numbers.  We also had a minimum runway length of 4000'.

The B-24 stalls down around 85 mph.  We don't do stalls in it...they are a bit exciting. <G>  For training we slow to the buffet.  Some of the guys early on stalled the airplane, it has a pretty nasty aileron buffet that can yank the yoke out of your hand if you're not expecting it, all that banging around isn't good for the airplane.

Both of them are unforgiving of aileron use at the stall.  If you try to pick a wing up using aileron you'll roll sharply toward the low wing...as one of the long time bombers said about the B-17 when we were doing approaches to stalls..."If you use aileron to pick up the wing we'll be upside down".   He also advised not to roll the Fortress. <G>

Interesting--shows the effect of all that planform taper...

[bj229r]

This is fascinating as hell!
<S>Colmbo 

[phatzo]

This is fascinating as hell!
<S>Colmbo 

its great to get the info first hand <S> colombo

[colmbo]

its great to get the info first hand <S> colombo

It was even greater getting to gather the info. 

[rabbidrabbit]

Agreed, by all means, feel free to share first hand knowledge.  If it isn't shared it will be lost over time.