Dear rotary engine subscribers,

On an aircraft that uses delta wings, if the ailerons and elevators are
fused into elevions; would it be possible for the aircraft to perform a
roll and pitch maneuver at the same time. On the rotaryeng website, the
article about the proposed VTOL uses delta wings.

http://www.rotaryeng.net/VTOL.html

On a standard bank
angle roll, there is a tendency for the aircraft to pitch down. In such
a situation would it be possible to still maintain the roll and pitch up
at the same time or are they mutually exclusive... as in not being able
to use one while the other is in operation.

One other thing. What are the advantages of using delta wings as opposed
to normal wings. A few googled sources point out that delta wings are
efficient only at high speeds and that it consumes more fuel at cruise
velocity to maintain level stable flight while using them. Mr. Lamar,
could you please tell me the reasons as to why you thought delta wings
would be better for your proposed VTOL?  Thank you

AJ

A very good question.
Yes it is possible but the chances are if you were in full roll mode
the pitch authority would be reduced. Also vice versa. It depends on the area
and maximum deflection of the elevons. As Jarrett's message applies to this situation as well:

"The Delta is going to help a lot with the ability to transition. Delta's can carry up to ~30 AOA prior to loss of lift."

The cruise efficiency depends on a lot of things. Yes that statement above may be true with equal wing area. However once you have enough low speed thrust to take off vertically there is no need for the same or a lot of wing area. You only need just enough wing area to maintain altitude at cruise. At high speeds the angle of attack approaches zero and so too the lift coefficient. Wing wetted area and a shorter span becomes more important.

The single heaviest part of the structure is the wing spar. If the span can be reduced the weight of the spar will also be drastically reduced. Also we need internal volume for fuel and the cooling system and the delta wing provides
that volume with a given airfoil thickness percentage.


Paul Lamar