[NSRCA-discussion] F17 barrel roll

Sun Aug 23 08:59:16 AKDT 2015

Ed- it's not from "insufficient caffeine", it's from ADS: Alcohol Deficiency
Syndrome. Easily cured BTW. J

John Pavlick

Cell: 203-417-4971

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Integrated Development Services

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On
Behalf Of Ed Alt via NSRCA-discussion
Sent: Sunday, August 23, 2015 9:43 AM
To: NSRCA List
Subject: Re: [NSRCA-discussion] F17 barrel roll

Oops.  In my first post, where I said "(when roll angle = 180 deg).  It's
really when it's 270 deg.  I'm so confused, must be due to insufficient
caffeine...

  _____  

To: nsrca-discussion at lists.nsrca.org
Date: Sun, 23 Aug 2015 09:33:16 -0400
Subject: Re: [NSRCA-discussion] F17 barrel roll
From: nsrca-discussion at lists.nsrca.org

Phil:

I couldn't really tell either, so I just tried to fly it with a stick plane.
Take the example that starts with the 45 up line.  I can't see how you would
avoid departing upwards from the 45 deg line and simultaneously get the
corkscrew shape started unless the maneuver was initiated with simultaneous
aileron, rudder and elevator.   I think the rudder has to be enough to
immediately skid the model and start bringing the nose down as positive
pitch input helps get the corkscrew angle set.  I guess I'll try just for
fun later today.

Ed

  _____  

Date: Sun, 23 Aug 2015 13:15:14 +0000
From: chuenkan at comcast.net
To: ed_alt at hotmail.com; nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] F17 barrel roll

If FAI/NSCRA have come up with a new definition of a barrel roll, then I
can't be of any help.  However, to do a "regular" old barrel roll, just do
what my aerobatics student does:  He is trying to learn to do 3 Horizontal
Rolls (the "3 horribles).  He can do one axial roll beautifully; he can
often get 2 pretty good ones; but 3???  He gets the elevator miss-timed and
does a very good barrel roll.  So, the idea of adding elevator (plus maybe
some rudder) should produce a barrel roll -- but I don't know if it would
fit the NSRCA definition if said roll.  From the posts, I can't tell what is
required.  Ah, yes, I love teaching -- that's why I gave up college tenure
and went to do laboratory research.  lol

Phil Spelt, KCRC Emeritus, Secretary
AMA 1294, Scientific Leader Member
SPA L-18, Board Member
(865) 435-1476v  (865) 604-0541c

  _____  

From: "Ed Alt via NSRCA-discussion" <nsrca-discussion at lists.nsrca.org>
To: "NSRCA List" <nsrca-discussion at lists.nsrca.org>
Sent: Sunday, August 23, 2015 8:35:05 AM
Subject: Re: [NSRCA-discussion] F17 barrel roll

I'm not sure , but after 100 years or so, it seems that the barrel roll may
have a new definition.  This appears to require that the model skid around
the entire rotation, which is not really how a barrel roll is typically done
as far as I know.  I believe that you would normally do one mainly with
simultaneous pitch and roll inputs, and maybe touches of rudder to keep that
coordinated, in much the same  way as  a coordinated turn would be done in a
full scale aircraft to keep the turn & bank indicator's ball centered. As a
result, it would present itself as if the aircraft were traveling along the
inside of a cylinder with both of it's main gear wheels always in contact
with its inner surface, hence the name barrel roll.  Executed this way, you
could do that Bob Hoover demonstration of keeping a glass of some liquid
perfectly still, resting on top of the instrument panel.

This definition seems to be more of a variation on an integrated roll, and
as a result you would expect to see the tail pointed at perhaps a 45 deg yaw
angle at one point (when roll angle = 90 deg), and the nose yawed at you 45
deg at another (when roll angle = 180 deg).  And I think that as a result it
would also mean that the wing tip in the direction of the roll would always
be in contact with the inner surface of the imaginary cylinder, instead of
both wheels.  Am I visualizing that correctly?  It seems like it would be
tricky to judge accurately.

Ed

  _____  

Date: Sat, 22 Aug 2015 23:10:49 -0700
To: underdw at gmail.com; nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] F17 barrel roll
From: nsrca-discussion at lists.nsrca.org

Hopefully this helps.

From: NSRCA-discussion on behalf of NSRCA List
Reply-To: Daniel Underkofler, NSRCA List
Date: Saturday, August 22, 2015 at 6:21 PM
To: NSRCA List
Subject: [NSRCA-discussion] F17 barrel roll

In F17 there is a cryptic aresti symbol that is described in the figure
description as a barrel roll.  Will somebody please describe this in more
detail and what control inputs will obtain the required result?

Thanks, Dan

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