Re: [RCSE] Supra ? Who couples flaps to ailerons?: Drela repost
I learned a long time ago that by coupling flaps to ailerons the model would track better. (And yes, every model) My first experience with this was with a slope racer (Swift 800) with a short tail moment, and undersized V-tail. I had trouble getting it to track properly at different ballasted weights, differing lift conditions and airspeeds. A slope racer needs to track well in all conditions and quickly changing conditions. When I say it would track better, I mean it would initiate roll with less adverse yaw. 30-40% seemed to work best (if the flaps were built to accept this much - if not, as much as I could get without binding). I have translated this to every model I've flown since then, and model set up is much easier. Dr Drela's explanation makes a lot of sense. I love it when the really smart aero guys verify my findings... ;-) I heard someone talking about "turning" with ailerons. We don't turn with ailerons, we initiate roll with ailerons. We want to do this as effortlessly and cleanly (axially) as possible, and create a minimum of adverse yaw. With the flaps coupled, I can run less total aileron throw for the required roll rate, less differential, and less rudder coupling to accomplish an axial roll into the bank. Thanks Mark D for putting so much time and effort into this soaring thing. And Mike L - I guess I'll switch my F3B models to poly ships... you know... to keep the wing clean and use rudder... ;-) And Mike Smith - insert Daryl giving the raspberries... ;-)~ (Sorry guys, but Mike didn't used to couple the flaps on his Sharons - I always... uh... "fixed" his program when I borrowed his planes) Have fun guys! D __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
Re: [RCSE] Supra ? Who couples flaps to ailerons?: Drela repost
If I couple the flaps and ailerons I like to use them 100%. the Roll rate is increased and to be honest I can't feel the extra drag. This flies in the face of conventional wisdom but its what I like... one big flaperon... JayOn 8/21/06, Michael Lachowski <[EMAIL PROTECTED]> wrote: If you are worried about keeping the wing clean, put in more dihedraland use rudder only.If you factor in bad designs and bad airfoils, there is definitely noone 'right' answer.Douglas, Brent wrote: > Now I'm really confused, even though I know the 'right' answer. I had a> very good flyer sell me on the opposite - just ailerons for turning,> keeping the center section of the wing 'clean'.> > I'm torn here - leverage really favors the outer surface, how much do> you really get from the flap help?>> Lift,> B.> RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to soaring-request@airage.com. Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format>> .>RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to soaring-request@airage.com. Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
Re: [RCSE] Supra ? Who couples flaps to ailerons?: Drela repost
If you are worried about keeping the wing clean, put in more dihedral and use rudder only. If you factor in bad designs and bad airfoils, there is definitely no one 'right' answer. Douglas, Brent wrote: Now I'm really confused, even though I know the 'right' answer. I had a very good flyer sell me on the opposite - just ailerons for turning, keeping the center section of the wing 'clean'. I'm torn here - leverage really favors the outer surface, how much do you really get from the flap help? Lift, B. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format . RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
Re: [RCSE] Supra ? Who couples flaps to ailerons?: Drela repost
Brent - As with so many issues that we all worry about endlessly, this one is pretty minor. Yes, the plane will be very slightly more efficient if you mix the flaps with the ailerons correctly. But, if a guy without his flaps and ailerons mixed puts his plane in better air and closer to the pin he'll beat you every time. The right answer is to set the plane up as best you can late at night when you can't fly anyway, and spend every spare daylight hour out learning how to fly and spot lift better in every conceivable situation. Try the different programming and see if you can tell any difference. Mostly you can't, so don't worry about it. As my OFB Jim Thomas says, "Do that pilot sh*t Bubba." happy trails Rob G From: "Douglas, Brent" <> To: "Soaring Digest" <soaring@airage.com> Subject: RE: [RCSE] Supra ? Who couples flaps to ailerons?: Drela repost Message-ID: <[EMAIL PROTECTED]> Now I'm really confused, even though I know the 'right' answer. I had a very good flyer sell me on the opposite - just ailerons for turning, keeping the center section of the wing 'clean'. =20 I'm torn here - leverage really favors the outer surface, how much do you really get from the flap help? Lift, B.=20 Check out AOL.com today. Breaking news, video search, pictures, email and IM. All on demand. Always Free.
Re: [RCSE] Supra ? Who couples flaps to ailerons?: Drela repost
Brent, Rick is right on with his great post, print it and glue it to the top of your flight box for future reference. Good Thermal Hunting Ray Hayes http://www.skybench.com Home of Wood Crafters - Original Message - From: "Rick Eckel" <[EMAIL PROTECTED]> To: "Douglas, Brent" <[EMAIL PROTECTED]>; "Soaring Digest" Sent: Monday, August 21, 2006 8:46 AM Subject: RE: [RCSE] Supra ? Who couples flaps to ailerons?: Drela repost > Brent, > > The wonderful thing about this hobby is that you don't have to > believe anyone! Give the options a personal flight test and decide > for yourself what you like the best. Aircraft design theory is a > wonderful thing but in the end what you are able to demonstrate for > yourself needs to be the deciding factor. > > Don't discount that in the future, as your skills progress, you may > find a different answer to the same question. Strange but true. > > Hope this helps > Rick > > > At 09:23 AM 8/21/2006, Douglas, Brent wrote: > >Now I'm really confused, even though I know the 'right' answer. I had a > >very good flyer sell me on the opposite - just ailerons for turning, > >keeping the center section of the wing 'clean'. > > > >I'm torn here - leverage really favors the outer surface, how much do > >you really get from the flap help? > > > >Lift, > >B. > >RCSE-List facilities provided by Model Airplane News. Send > >"subscribe" and "unsubscribe" requests to > >[EMAIL PROTECTED] Please note that subscribe and > >unsubscribe messages must be sent in text only format with MIME > >turned off. Email sent from web based email such as Hotmail and AOL > >are generally NOT in text format > > RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format > RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
RE: [RCSE] Supra ? Who couples flaps to ailerons?: Drela repost
Brent, The wonderful thing about this hobby is that you don't have to believe anyone! Give the options a personal flight test and decide for yourself what you like the best. Aircraft design theory is a wonderful thing but in the end what you are able to demonstrate for yourself needs to be the deciding factor. Don't discount that in the future, as your skills progress, you may find a different answer to the same question. Strange but true. Hope this helps Rick At 09:23 AM 8/21/2006, Douglas, Brent wrote: Now I'm really confused, even though I know the 'right' answer. I had a very good flyer sell me on the opposite - just ailerons for turning, keeping the center section of the wing 'clean'. I'm torn here - leverage really favors the outer surface, how much do you really get from the flap help? Lift, B. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
RE: [RCSE] Supra ? Who couples flaps to ailerons?: Drela repost
Now I'm really confused, even though I know the 'right' answer. I had a very good flyer sell me on the opposite - just ailerons for turning, keeping the center section of the wing 'clean'. I'm torn here - leverage really favors the outer surface, how much do you really get from the flap help? Lift, B. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
Re: [RCSE] Supra ? Who couples flaps to ailerons?: Drela repost
All, I saved this post from Dr. Drela from October 2003; it's long but very good. Since he originally posted it to the exchange, I'm presuming a repost is OK. Barry Andersen From Dr. Drela: Deflected ailerons deform the load distribution away from the ideal near-elliptical shape, and hence increase induced drag. Partially slaving the flaps to the ailerons can alleviate this load distribution deformation, and thus mitigate the ailerons' CDi penalty. The question is what's the optimum amount of ail-> flap mixing. The lowest-drag aileron system is wing-warping as used by the Wright Brothers -- the wing is linearly twisted from tip to tip. When such a twisted wing reaches its steady roll rate, the load distribution returns to its optimum level-flight shape, and the drag penalty is zero. With a finite number of hinged control surfaces such a linear twist cannot be achieved. But it can be approximated as close as possible if each surface's deflection is made proportional to its distance from the aircraft's centerline, measured at the surface midpoint. If the four control surfaces have equal span, we then have: surfacemid_span_loc. deflection ---- -- L.aile. -3/4 -100% L.flap-1/4-33% R.flap+1/4+33% R.aile. +3/4 +100% So for this wing the flap motion should be 33% of the aileron motion. Using AVL I've verified that this mixing ratio produces very nearly the smallest induced drag penalty. If the flap span differs from the aileron span, the table above can be adjusted accordingly. Longer flaps will have larger travel and vice versa. BTW, this "distance-proportial deflection rule" strongly argues against stopping the ailerons short of the tip. The resulting unhinged tip portion should in fact have the largest deflection. The "distance-proportial deflection rule" can be fudged if there is a tip stall problem in a sustained turn, where some opposite aileron must is held. By increasing flap travel over its "optimum" amount, the flaps can carry a greater share of the roll power, which reduces the required downward deflection of the inside aileron, and thus delays tip stall. So if your TD glider has insufficient tip stall margin, I suggest increasing the flap mixing and you should see some improvement. The extreme case would be 100% flap mixing, which mimics full-span flaperons. Flaperons give excellent tip stall resistance, as is obvious to anyone who flies a DLG with a good 2-servo wing. A 4-servo TD wing with decent planform should not need to go to this extreme, especially if it has some washout like the Aegea wing. On Aug 18, 2006, at 11:43 PM, Stan Myers wrote: If so, how much? If not, when/why? Thanks Stan RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to soaring- [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
