[NSRCA-discussion] F17 barrel roll

Sun Aug 23 06:00:37 AKDT 2015

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>
> *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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