[NSRCA-discussion] 747 Snap Entry?

[rcmaster199 at aol.com]

A few of us were discussing just such an occurence recently which 
apparently happened by accident and darned near crashed the plane. Dean 
remembered the details which went something like this:

The pilot of the 727 about 20 years ago had the plane trimmed as far 
aft as possible and had inputed a bit of flap to use fuel most 
efficiently. The co-pilot, soon after returning from a visit to the 
loo, saw the trimmed flap and flipped the switch to return the flap to 
neutral. This action immediately made the plane too tail heavy which 
made the plane do a pretty violent half snap to inverted. The pilot 
lost close to 25k feet pulling the plane out of the dive, which he did 
successfully but not before deploying the gear to slow the crate down. 
That had to be some kind of experience

Legend has it that the pilot then went straight to loo himself to 
change his britches (G)

Matt

-----Original Message-----
From: Koenig, Tom <Tom.Koenig at actewagl.com.au>
To: General pattern discussion <nsrca-discussion at lists.nsrca.org>
Sent: Mon, 30 Jun 2008 10:25 pm
Subject: Re: [NSRCA-discussion] 747 Snap Entry?

 Hey John,

Out of interest.....has anyone ever attempted a snap in an airliner???

I have heard of a captain doing a slow roll in a 747....but a snap? Is
it possible?? What does a simulator do when pushed to such limits ( I
know a simulator cant snap BTW...well, I assume any way LOL!!)

Tom

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of John
Gayer
Sent: Tuesday, 1 July 2008 11:42 AM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] Snap Entry

Actually a snap can occur without any aileron input...but I challenge
anyone to show a pattern ship doing a snap roll on a 45 degree downline
without ailerons.

The approach snap can occur with only the use of elevator and it
involves one wing panel stalling before the other. Try an approach with
crossed controls(aileron/rudder with some power. pull the nose up
gradually and see which wing drops. It will be the wing with the aileron
trailing edge down. This is contrary to what we see in a pattern snap
roll which always snaps in the direction of the aileron deflection thus
indicating the lack of any stalled condition

John

seefo at san.rr.com wrote:

>Just to stir the pot a little further..
>
>I'm not sure a contemporary pattern plane can generate enough pitch
rate to reach critical angle of attack and properly perform a snap roll.
I think it's far more likely that we're seeing nothing but a heavily
yawed aileron roll, with the pitch break only being shown to judges to
convince them there is actually a stall happening, when in fact there is
not.
>
>If a snap cannot occur using ONLY elevator and rudder, then the wing is
not stalling. Aileron inputs into a snap actually inhibit flow
separation, as the inboard wing angle of attack is drastically reduced,
and the outboard wing AoA is drastically increased.
>
>But since there is no way to actually determine what is happening
aerodynamically on an F3A airplane, the best a pilot can do is fly the
airplane to what the judges expect to see based upon the rules. It
really doesn't matter what the control inputs are if the airplane LOOKS
like it's doing the right maneuver.
>_______________________________________________
>NSRCA-discussion mailing list
>NSRCA-discussion at lists.nsrca.org
>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>
>
>
_______________________________________________
NSRCA-discussion mailing list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
_______________________________________________
NSRCA-discussion mailing list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion