wonwinglo

Received a note from my good friend Peter Simpson this morning regarding the sad crash of the B-52 Bomber at the weekend,this is what he has to say-

The Rumour is that only one engine survived. The model was sponsored
by the jet engine manufacturer as an advert. The pilot was contracted
to fly the B52 at a set number of shows as part of the deal. Hence he
would have been under considerable pressure to fly even in the poor
conditions.

Here is my analysis for those interested. I was not there and only
have the video as evidence. There are other theorys out there!

Stability of a wing caused by Dihedral.
On an aircraft with Dihedral, in a banked condition the low wing has
a greater planform area than the high wing, and therefore gives
greater lift leading to the stabalising effect of lifting the low
wing. In exactly the same way an aircraft with anhedral is inherently
unstable as the high wing has more lift than the low wing leading to
an increase in the bank.On an aircraft of this type what you really
want is stability, therefore I assume that the only reason that the
full size B52 aircraft has anhedral is because it needs that castor
at the end of the wing to support its weight.

The operation of Ailerons.
Firstly aircraft roll is a reaction of air being deflected off the
trailing edge of the aileron.
Secondly ailerons change the lift characteristics of a wing, so in a
right hand roll, the left wing aileron goes down, increasing the
overall angle of attack of the wing and therefore the lift. The right
aileron goes up and thus decreases the overall angle of attack and
reduces the lift in the wing.

In order for the aircraft to roll, one wing must be providing more
lift than the other. With an anhedral wing in a banked condition the
low wing offers considerably less lift than the high wing, however in
order to reduce the bank the lift generated by the low wing must be
increased and the lift generated by the high wing must be reduced.
The ailerons are used to achieve this. However the more the angle of
bank of an anhedral aircraft, the greater the natural differential in
lift of the wings, therefore the greater the required change in lift
by the ailerons.

Conclusion
The ailerons can only achieve a finite change to the lift
characteristics of the wing. With an anhedral wing, the greater the
angle of bank the greater the difference in lift offered by the wing.
Therefore there must be an angle at which the difference in lift
generated by the wings exceeds the difference in lift that can be
generated by the aileron.

My conclusion is that the model B52 did not stall, it simply exceeded
this angle of bank, therefore there was no way that any control input
would correct the bank and the enevitable happened. Given the
conditions, it is highly likely that turbulance caused the excessive
bank rather than bad piloting and no pilot, however skillful would
have been able to retrieve the situatuon. My team were supposed to be
displaying this weekend, and our aircraft are much more controllable
and rapid in response than the B52. We elected not to fly due to the
conditions.

Thanks Peter for that update,my own observations on this to follow...

__________________
'And there I was oil on my goggles from a broken pipe,then I looked at the altimeter,all I could see was the makers name !'
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