Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

servo's and speed planes

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Old 01-08-2006, 06:20 AM
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HaveBlue
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Default servo's and speed planes

fellow bretheren, what do you guys use for high torque value servo's in planes like whiplashes and diamond dust ..I ask in reference to info provided by Bagostiks stating that for high speed applications useing 200 oz/in servo's were in order... all that is fine ..but I believe that servo's in this catergory all?/mostly use metal gears, the part thats puzzling me is , that on more than one occassion I have been advised that metal gear servos have to much play so nylon gears are better so whats the go? I know some of the high rated Hitech servos use karbonite gears ( I suppose this is a stronger type of nylon).. but are metal geared servos so sloppy.. I do use them myself but those are in planes only doing top's of 130mph approx


any comments?
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Old 01-08-2006, 09:04 AM
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Strykaas
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Default RE: servo's and speed planes

Graupner/JR C4421 here...
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Old 01-08-2006, 09:56 AM
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Mike Connor
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Default RE: servo's and speed planes

I started off with standard JR BB servos in my first Jett powered Dust and got away with it. After changing to Hitec 225 BB nylon gear servos there was a huge difference. The 225's are used my many Q-500 guys. The Whiplash requires more servo then the DD because of a design issue that leaves the hinge line VERY stiff.
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Old 01-08-2006, 10:08 AM
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daven
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Default RE: servo's and speed planes

Futaba 9650
JR 3421
Hitec HS5345

those are the most common digital servos used in Q40 or Q500 racing in the 160-190 mph range. I can't comment on the Whiplash, in fact, I can't even remember what I used in mine. I think they were Hitec 605's, 615's or 625's. Basically a heavy duty standard sized servo. Didn't last long enough to figure out if they were up to the task.
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Old 01-08-2006, 07:57 PM
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HaveBlue
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Default RE: servo's and speed planes

thanks for the pointers guys, I admit the dust doesnt worry me that much , as I liken it to a magnum.
The whiplash does have a stiff hinge..but manily wanted the overall jist on the servos..which you have all kindly supplied

THANKS![sm=thumbup.gif]
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Old 01-09-2006, 02:11 PM
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rmenke
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Default RE: servo's and speed planes

Haveblue:

Have you noticed that some of the guys always seem to have flutter, and some of the guys never? One of our Q-500 guys seems to always have some flutter at some speed. He is always building a replacement casuse it is going in soon. He uses Hitec 225's everywhere. What bugs heck out of me is that he will trial a new airplane, hear a minor flutter, and ignor it. I seldom see the same plane again after his next race outting. Then there are the super picky guys who seem to never get flutters. Be a super pickey guy, it pays in the long run. Iff your servo has any play detectable, replace the gears. If still a little sloppy, sell it to a bud for his 3-D cheap. You will both be happy in the long run. There should be no play in your linkage anywhere. If you use metal cleivis on threaded rod ends, get rid of them and go to the plastic "Hays" type, black plastic with a metal pin. No slop and very tough. Long pushrods like on the Alley Cat elevator and rudder should be always checked for buz. If you can feel or hear the unusual vibration created, or even suspect its there, provide a middle of the fuze support. You may need several. The main point here is to get the surfaces and linkages right, and about anything in the servo dept. will work ok, temered with good judgement. My Yellow Jacket has 225's on elevator, rudder and motor, a JR 86 11 on the aileron. The 8611 is sooo overkill at 280 oz or so, but this surface started out stiff and still is. The Alley Cat will have a 86 or 8411 elevator, cause I have them new and unused and want this thing to center spot on, a cheepe standard Jr 537 BB servo on rudder, motor, and 4711s on each aileron. My experience with the JR 4711 is that they will warn you in little ways when they start to go south, never a failure for me yet. Even if you are going to use surface tape to eleminate control surface gap, seal both sides of the surface with ultracote or monocote. Overkill, yes, but the combo dampens any tendancy to flutter. None of your moving control surfaces should be thicker at the joint than the first surface. Almost automatic flutter! Problem with most flutters is that you don't know what surface is giving the problem until it lets go, then it no longer matters as you have the old lawn dart, over 100 mph, not much will be left. Have you used any of the control "fences" provided with the AC? If so, please send me a pic, am not sure what the heck they intend, instructions are non existant. Thanks, ENJOY.
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Old 01-10-2006, 12:52 AM
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Default RE: servo's and speed planes

Hi rmenke, I guess what i was really getting mostly refered to the whiplash, although, I wanted an overall general idea when it came to the high torque servos like the JR8611..

I mostly use hitech servos as I use a hitech radio, the eclipse7, so far this has done me well,and Ive had very few qlitches or failures(knock on wood), but then again with work I get limited use too.

my main concern was most of the high torque servos use metal gears , and Ive been told they are to sloppy, so wasnt sure which way to go..like I said I use metal gears servos in the form of HS625's which are great.

As for linkages I pay extra attention here and keep re-checking them ..pre and post flight

as far as fences go..I dont have anything that use's fences..I mostly have prop jets and flying wings..considered me the bottom of the ladder as far as true speed planes go..but I have learned alot..with still lots more to go, and will apply proven methods as the need arises

cheers
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