Proof that B17 couldn't dive bomb

[Simaril]

I was surfing for tech data on B-17, and came across a single page from the original Technical Orders that accompanied the more commonly known pilot manuals. On it were 2 paragraphs headed "Dives". To quote:


The structural factors limiting the dive speed to 305 mph are the engine ring cowl strength, the wing leading edge de-icer boot strength, the pilot compartment winshield and enclosure strength, and the critical flutter speed. The engine ring cowl has been designed to wthstand 420 mph. Windshield and pilot compartment have ample margin at 305 mph. The wing leading edge de-icer boots begin to rise slightly form the wing at 305 mph, and any excessive additional speed would probably lift the upper portion of the boot well abovve the wing surface and allow it to flap severly against the leading edge, thus causing a structural failure.

Structural failure at the wing leading edge is generally considered a bad thing.

Secondly, the next paragraph places a great deal of emphasis on the elevator trim tabs in dives, especially when recovering. I dont have time to type it out (and I cant find my OCR program this am -- grrr), but this passage strongly implies that elevator tolerances are limiting factors when pulling out even from dives limited to 305 mph or less. And B-17s were designed with greater strength at teh cost of carry capacity. One wonders how less robust frames could ahve tolerated dives. (And I'd just love to see what that slender Davis wing would do at dive recovery G loads.....)

I never would have expected that wing de-icer boots would be the weak link for diving B17s, but you can bet on every aircraft such a weak link exists. I'd suspect that most are limited by elevator G tolerances if nothing else.


Bottom line -- buffs were designed for level bombing. In order to maximize payload, range, and effectiveness the competent aeronautical engineers WOULD NOT include structural strengths to also permit dive bombing. It would be stupid to trade off load capacity to get structural strength for a silly mission like dive bombing buffs --  and there WAS a war on.  


Conclusions:
1. Airframes designed for level bombing shuld not be permitted to tolerate high G maneuvers like dive bombing and pull outs.
2. Based on data presented, B-17s should have wing leading edge structural failure at 310- 325 mph.

[bozon]

interesting.
What are the "de-icer boots" anyway? Something an eskimo would wear for a warm and fuzzy feeling in their feet?

Bozon

[4510]

Originally posted by bozon
interesting.
What are the "de-icer boots" anyway? Something an eskimo would wear for a warm and fuzzy feeling in their feet?

Bozon

IIRC, On a B-17 there were rubberized sheeths that were along the leading edges of the wings... they routed warmed air thru them.  The heat plus the expansion (liking softly blowing up a balloon) would shed the ice.

Think that is how they worked.... but it is very early in the morning...

[Mak333]

Nice job Simaril, nice effort.  Now...Is anything going to be done about this..?

[Midnight]

Due to AH not modeling High Altitude lack of oxygen and heat (by way of pilot oxygen systems not modeled and wing icing, etc. not modeled) the B17s have had their wing deicing boots removed, so no high speed effect is induced.

This is the same reason why we see planes with no O2 systems flying at 20K+

[Mak333]

But, you'd still think a B17 should be able to be modelled to not pull out after 400 mph.  Or find some way to inflict damage when reaching speeds past 350 mph.  Seems legit.  I mean, they can model other planes to compress at certain speeds, why not have the 17's and other bombers "compress" at certain speeds.  This may stop the dive bombing and also create more of a realistic descend time when landing instead of just plummitting to the earth and then pull out at 1k just before the runway.

[FiLtH]

Since most bombers fly at 100ft-3000ft, dive speed and ice don't seem like much of an issue

[seabat]

no argument with eliminating dive bombing with the heavy's.

I seem to remember reading that de-icer boots ended up getting removed after flak damage instead of repaired due to short supply and short turn around times required for the next missions.

[Wurger]

I agree, something really needs to be done to limit dives in buffs and require level flight to release bombs.

Bazi

[Cooley]

What some other guy said,,,,,and very simple fix

Being only able to drop eggs from Norden Bombsite position
for Lanc, B17,B24,B26 and Ki-67

[SKBG Seadog]

The B-17 has been messed with too much as it is. With no crew, guns,bombing calibrations, ect.

[GRUNHERZ]

Originally posted by SKBG Seadog
The B-17 has been messed with too much as it is. With no crew, guns,bombing calibrations, ect.

Bombing calibrations are "messing" wth the B17 to you...  I guess yiu want the realisdtic laser guided old AH bombs just lier they had back in the real war...

[humble]

I'm curious what the "G" rating for a B-17 (or other buff) is. I know that bob hoover used to do acrobatics in a twin with a "utility" rating (think that is a 3.2G limit). Anyway I've never seen anyone pop the wings off a buff recovering from a dive like you do in a pony or or tempest 262 etc. I'd just be a realistic G limiter and plane breaks up above that like A-26 in did in AW....

[VWE]

I've popped the wings off a B-26 while dogfighting a time or two...

[airbumba]

I wanna see a pic of VWE doin a loop in his spook plane, hehe.