[NSRCA-discussion] 747 Snap Entry?

[Gerald Gallagher]

I might add that when you lowered the flaps even a little you would have to
trim nose down on all the 727s. I am taking your statement of "trimmed aft"
as nose up trim. 

Jerry Gallagher



-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Gerald
Gallagher
Sent: Tuesday, July 01, 2008 6:04 PM
To: 'General pattern discussion'
Subject: Re: [NSRCA-discussion] 747 Snap Entry?


I was a pilot with TWA & knew the captain that is accused of this, also a
TWA Pilot. To this day he denies this ever happened & so do the 2 other crew
members that were flying that 727. The loss of altitude was, according to
the three crewmembers aboard was clear air turbulence. I believe the pilot,
but I am prejudice. 

Jerry Gallagher



-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of
rcmaster199 at aol.com
Sent: Tuesday, July 01, 2008 5:47 PM
To: nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] 747 Snap Entry?


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.
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