[NSRCA-discussion] F17 barrel roll

Sun Aug 23 06:22:46 AKDT 2015

Thanks for the helpful and amusing replies!
John, the only way we will be able to arrive at the correct geometry will
be a lengthy discussion with the help of a few beers!
Then we'll go out and fly F17 at your contest on Sunday?

Dan

On Sun, Aug 23, 2015 at 8:00 AM, John Gayer via NSRCA-discussion <
nsrca-discussion at lists.nsrca.org> wrote:

> I don't think they are describing pictorially what they want.
>
> If you are going to fly the inside of a tube with a spiral pitch of 45
> degrees, you need to enter the tube parallel to the surface, not at an
> attitude of 45 degrees to the centerline of the tube.
> Also if you are flying a barrel roll with a vertical displacement of 25
> meters up and down, then you must go in and out 25 meters as well. How do
> you judge that?
>
> Despite what they say, it appears that you need to fly this maneuver in a
> plane as shown in the first slide, not the inside of a tube as in the
> second slide. Then entering at 45 degrees make perfect sense and requires
> coordination of all four controls to do well.... but it's not a barrel roll.
>
> John
>
> On 8/23/2015 7:33 AM, Ed Alt via NSRCA-discussion wrote:
>
> 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>
> <nsrca-discussion at lists.nsrca.org>
> *To: *"NSRCA List" <nsrca-discussion at lists.nsrca.org>
> <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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