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Re: Heinkel He-177, an aerodynamical question

Posted by Christer on Wed Aug 14, 2002 05:34:25 AM

In reply top Heinkel He-177, an aerodynamical question posted by Cees on Wed Aug 14, 2002 03:02:20 AM

Anything that is protruding into or deflecting the airflow not only adds to the total drag but, it can also affect controllability. An example of this is the F4U Corsair which avoided the use of maximum flap settings when performing cross wind landings. The flaps deflected the airflow away from the tailplane and at high angle of attack it became rather "unpredictable".

The He 177 has an unusual landing gear layout with two struts and wheels attached to each wing at the position of the engine nacelles. The main aerodynamic effect of lowering the landing gear, apart from increased drag, would be a trim change. You increase drag with a moment arm below the centre of gravity which will pitch the nose downwards. This is not a violent pitch movement and can be easily held by the stick and was probably trimmed out on approach.
I?m not sure but, I think that the double struts were retracted inwards/outwards. A picture and a drawing, on the pages to which I linked, indicate that.
The wheel well doors are split in halves to open, facing the airflow, in order to retract or lower the landing gear but, they are opened only while the landing gear is either retracting or lowering. When being in or out the doors are closed. There are no gaping holes in the wing with the landing gear down. With the doors opened the drag was increased quite radically and it was probably rather noisy. I don?t know the first thing about flying large aircraft but, they do possess some inertia and maybe the landing gear was lowered when a speed decrease was neccessary and they used the drag to bleed energy?!?

Links, I hope they work, if not; copy and paste.

http://www.simviation.com/fsdcbainhe177.htm

http://www.geocities.com/wetaluft/he177.html

He 177

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