[NSRCA-discussion] Snaps

[Doug Cronkhite]

The INBOARD wing dumps lift as a result of the increases angle of attack AND
the rapid reduction of airspeed (by a sharp yaw moment - rudder input). The
outboard wing's lift and drag increase rapidly. If the outboard wing dumped
lift you'd get no rotation at all or very little. Some airplanes actually
snap much better with no aileron usage as the changes in angle of attack on
the inboard wing causes it to keep flying and not dump the lift from the yaw
input.

 

I think the biggest problem pattern aircraft have with performing proper
snaps is the long long tail moments keep things so stable that it's very
hard to generate the critical angle of attack required to get the stall to
happen. So you see barrel rolls with VERY high G-loads on the aircraft. 

 

In full scale aerobatics, there is nearly no G-loading once the stall
occurs, except for the rotational forces of the autorotation of the
aircraft. There is some G leading up to the break, but once that happens,
it's all kind of non-stressful. 

 

-Doug

 

 

  _____  

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of
Rcmaster199 at aol.com
Sent: Saturday, July 08, 2006 12:45 PM
To: nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] Snaps

 

In a message dated 7/8/2006 2:09:25 PM Eastern Standard Time,
natpenton at centurytel.net writes:

Matt

Regards. Two comments. 

Snap characteristics are independent of scale. The only thing that changes
is the clock ( due to changes in moments of inertia ). 

When the rudder is applied it is the outboard wing that exceeds the stall
AOA and dumps. Actually it is not much of a lift dump but a huge jump in
drag.

Nat true. Moments of inertia are design parameters. So are several other key
parameters that may make or break a model's ability to perform snaps. That
was my point.

 

I agree in terms of AOA (outboard aileron low) and drag increase but I am
not as sure regards to lift. I know what you are saying though. 

 

One question: how does the outboard panel lift over the top if its lift has
been dumped?

 

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.nsrca.org/pipermail/nsrca-discussion/attachments/20060709/eb2302e4/attachment.html