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Dec 01, 2002, 09:40 PM
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Wing Incidence For a Speed 400 Pylon Racer?


Can anyone give me a recommendation for wing incidence? My wing doesn't fit in the saddle very well so I want to make sure I get the incidence right...

Also what volt speed 400 motor and how many/what type cells would you recommend?
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Dec 01, 2002, 11:49 PM
Electron Abuser
On incidence - ? probably 0 degrees.
Cells (7) N500AR, Rocket 400 (6-7.2 volt), 4.7-4.7 prop. Over 10 laps or 1min 50 secs run time.

Could try - 6 cells N700 AR, Graupner 4.8 volt, slightly smaller prop. (Might have to go to N800 Ar Cells. N700AR are not available in US. However Hoellin in germany has N700AR. Just got some shipped here. http://www.hoellein.com they understand english email orders. Can get the 4.8 volt graupners there as well for cheap - ~$5.00

Buy the Kontronick Rhondo speed 400 controller that solders on the back of the motor. $29. For the 6 cell setup, you have to get a different speed control that BEC works for 6 cells.


This is a really cheap and fast setup all assuming you really want to race legal NEAC speed 400 pylon. I havent tried the 6 cell setup, but will be doing so shortly. The 6 cell setup is because the N700AR batteries keep their voltage up for the entire race and have lower internal resistance. You have to use 6 to keep the weight down. This is a critical item that most sport racers don't understand, the voltage drop. You cant just add cells in 7 cell pylon as you can in a sport plane.

The new green N500AR batteries don't run as well as the old red N500AR batteries that are not available. Dave Campbell of Fastecomposites.com detailed the 6 cell setup for me. I will be trying one at next years Muncie Nats for speed 400 pylon.
Dec 02, 2002, 01:33 AM
RCGroups Author
SoarNeck's Avatar
I typically run 0 degrees on the main wing and -1/2 degree on the stab. Elevator is neutral at speed, which tells me my incidences are about right.

Unfortunately, my models are beginning to overspeed their wings. I had some flutter issues on the test flight that damaged one aileron. I'll have to do a little bit of work to allow it to get up to speed. 13.8 oz w/8cells and 3 servos, S400 6v 5x5 (local rules).
Dec 02, 2002, 11:21 AM
Vice President at MultiGP
Admiral_Red's Avatar
Soarneck,

Just a suggestion, but maybe if you don't take the ailerons all the way to the tip, you might lose some of the flutter. Tip vorticies have caused numerous flutter problem on my faster glow models.

Not sure what you are doing in the way of hooking up the ailerons, but I spied something interesting on George Parks '99 Nats winner Switchblade. He used brass tube along the whole length of the leading edge of the aileron that works as both a wiper and a stiffener. The aileron torque rod was CA'd into the brass, and it made for a great positive linkage.

James

Oh yeah, what tint did you use in the bagging process?
Dec 02, 2002, 11:49 AM
RCGroups Author
SoarNeck's Avatar
I typically don't take them out to the tip, but was doing so on suggestion of Dr. Drela. My next wing won't use them full-span. I'm using an 0.030 carbon rod as a closeout, since brass is a little heavy for my liking. I can take a photo of my aileron linkages, but I don't think that that was the problem (zero-slop).

After the first flight (fluttered at half-throttle), I taped the tips stationary so that the whole aileron warped underl control deflection. It worked fine until I got overzealous and tried a full-throttle dive from about 600 feet So sue me, I'd just been flying my Stinger!

The tint is blaze orange from CST.
Last edited by SoarNeck; Dec 02, 2002 at 12:17 PM.
Dec 02, 2002, 11:59 AM
Vice President at MultiGP
Admiral_Red's Avatar
I would listen to Mr. Drela on most accounts, but what was the logic if there was an explanation? I can understand gliders using ailerons all the way to the tips for efficiency...hence six servo wings and trilerons, but for speed? I suppose maybe he was thinking along the lines of keeping drag down when deflecting ailerons for roll.

I won't sue you, I would try the same thing...600 feet is a good place to start a BLAZING flyby.

James
Dec 02, 2002, 12:16 PM
RCGroups Author
SoarNeck's Avatar
He pointed to the Miraj, current F3F record holder and DS machine, as an example of taking ailerons to the tip. I'm sure it was an efficiency bonus that was the intended benefit. Unfortunately, it's MUCH easier to close-out a sailplane aileron than a S400 aileron.

Oh well, no major harm done. I'll build a new wing to get the 0.2 or 0.3 oz back that the carbon rod added, and use this as a backup. I'm getting just a little wing flex in sharp pylon turns, so I think I finally have my layup correct.


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