FW: Armadillo 4/18

reposted to list with permission (2 emails stiched togther)

At 04:01 PM 4/19/2004 +1000, you wrote:
>just something i noticed when looking at your vane vehicle
>it looks like the vanes are pivoted in the center, wouldnt that make them
>unstable in the gas flow (ie fluttering when at 0 angle) and run the risk
of
>a broken actuator driving to max deflection?
>wouldnt a design that had them hinged at the top so they are pushed to 0
>deflection be "nicer" something like an aleron or some such?

It takes much higher actuator forces if the vanes are hinged at the
top.  For supersonic flows, the center of pressure is in the middle of the
plate.  "Stability" doesn't really help anything with a computer controlled
vane, because it is constantly adjusting anyway.

John Carmack

At 04:52 PM 4/19/2004 +1000, you wrote:
>is flutter not an issue because it'd need to happen at too high a
frequency?
>though I spose flutter would still be an issue no matter where it was
>hinged, I just like things that tend to "self correct" or at least fail
>minimal.

I don't expect stainless plates at that aspect ratio to have any noticeable
flutter.


>btw mind if I post this and the last question on list? I meant to reply
>onlist but forgot to use reply all and it does seem to have a fair ammount
>of educational content (least for simple people like me ;->)

No problem.

John Carmack