[NSRCA-discussion] YS Questions+more - Rolls
glmiller3 at suddenlink.net
glmiller3 at suddenlink.net
Fri Mar 7 03:01:40 AKST 2008
OOps, my mistake. But my point is that I thought we "dialed in differential" to prevent yaw in rolls induced by this differential drag. The designers here (Nat, Brian, et al) seem to be saying that "modern designs" aren't subject to this phenomenon....I was wondering why they don't "need" differential any more.
George
---- Ken Velez <kvelez at comcast.net> wrote:
=============
Gorge Nat is correct, think about it this way. The down deflected control surface produces more lift. lift = Drag. Lift is the force that's opposes to gravity"
Ken
----- Original Message -----
From: Nat Penton
To: NSRCA Mailing List
Sent: Thursday, March 06, 2008 6:08 PM
Subject: Re: [NSRCA-discussion] YS Questions+more - Rolls
George, I believe the down aileron produces the most drag ( re adverse yaw ), but, over half of our rolls occur in verticals.
----- Original Message -----
From: Del Rykert
To: NSRCA Mailing List
Sent: Thursday, March 06, 2008 2:11 PM
Subject: Re: [NSRCA-discussion] YS Questions+more - Rolls
The general consensus has been that the faster moving molecules over the top surface don't require as big as a deflection as the aileron that deflects towards the bottom of the plane. What one tries to achieve is the plane tracks as purely straight on a string as possible while one rolls both directions without introducing any yaw.
Del
----- Original Message -----
From: <glmiller3 at suddenlink.net>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Thursday, March 06, 2008 2:49 PM
Subject: Re: [NSRCA-discussion] YS Questions+more - Rolls
> Nat and all you other aerodynamicists,
>
> I thought that the rational for "aileron differential" was that upward deflection causes more drag than downward deflection so to equalize drag and prevent yaw with aileron deflection, aileron differential is needed. It seems that you guys are now saying that ain't so. Please elaborate.
>
> George
>
> ---- Nat Penton <natpenton at centurytel.net> wrote:
>
> =============
> IMO center hinged or top hinged is OK. With top hinge, to achieve equal vertical travel of the trailing edge requires different angular travel, up vs down. The objective is zero aerodynamic differential.
>
> Ron I don't think a fairing would prevent separation but, how are you able to fair the gap using the top hinge ? Nat
> ----- Original Message -----
> From: ronlock at comcast.net
> To: NSRCA Mailing List
> Sent: Thursday, March 06, 2008 7:20 AM
> Subject: Re: [NSRCA-discussion] YS Questions+more - Rolls
>
>
> And while your at it, I'd appreciate some discussion of the impact of the top hinge system as seen on Viavat, and Prestige birds - (top hinged, with fairing that eliminates the gap at deflection)
>
> Thanks, Ron Lockhart
>
> -------------- Original message --------------
> From: vicenterc at comcast.net
>
> Nat,
>
> Could you explain why the differential should be different for non-center hinged? I understand that the mechanical configuration of non-center hinged requires differential to obtain same travel in both directions. However, the travel up and down should be close to equal.
>
> Thanks,
>
> --
> Vicente "Vince" Bortone
>
> -------------- Original message --------------
> From: "Nat Penton" <natpenton at centurytel.net>
>
> Tom
> It's just something that is peculiar to the Southern Hemisphere.
>
> Changing wing incidence will not help. Unless things are really screwed up <G>, at our roll rates, centrifugal forces are too low to cause a problem. You want zero differential, aero speaking ( same up/down if center hinged ).
>
> I find the best check is the fast half-roll in the vertical up. Regards Nat
> ----- Original Message -----
> From: Koenig, Tom
> To: NSRCA Mailing List
> Sent: Wednesday, March 05, 2008 7:24 PM
> Subject: Re: [NSRCA-discussion] YS Questions+more
>
>
> Hi Troy!
>
> Thanks for the info. I thought you would be toiling away on the next developmental stage of these engines!!
>
> Hopefully soon, I can find the time to get flying again. I am looking forward to running this little beast. I am still a little concerned in keeping it quiet though.
>
> Four blade props? I have some of the 18.1 x 12 two bladers but I just cant see how I'll shut the thing up with these paint stirrers??
>
> Also-one more question to any of you out there in pattern land.
>
> I have struggled with aileron differential for years. I am just not happy with the rolls. I have tried various design fixes-but about the only one that seems to work is to get the wing back to 0-0 ( which can be achieved by a few ways, design, mix or thumbs) Differential itself does not seem to work if the wing is POA ( well...it works for half the roll !)
> Another black magic fix appears to be to run parallel ailerons-but this only 'sorta' seems to fix it. I like the feel of equal% chord ailerons however.
>
> I am frustrated with it-I like my planes to roll as if they had a string up its ...........well you know!
>
> OK-any 'secrets' I need to know??? Very good elevator work fixes it ( hence my 0-0 comment)
>
> Tom
>
>
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