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 choice for Diamond Dust

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Old 09-09-2006, 05:18 AM
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HaveBlue
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Default servo choice for Diamond Dust

what do you guys think I could get away with for elevon servos on this dust, I have a set of 625 mg servos but wonder if I could get away with some simple 475's instead...

I have almost finished before I glass it( I know most wont think glassing it is a good idea but I think it will be better than flying a snare drum)...

the engine ( Irvine 40 RE + CF Bolly pipe), servo's, tank( small issue to work out with pipe clearance over the tank.. might make my own tank for it) etc will be fully enclosed in a cowling that will go all the way back to the end of the pipe

and yes at a later date I hope to replace the engine with a Jett 60 LX
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Old 09-09-2006, 09:03 AM
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Default RE: servo choice for Diamond Dust

I used Futaba 148, no problem, I don't think there's any great load on them.

You made your DD into a Whiplash! Cool.
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Old 09-09-2006, 09:40 AM
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Mike Connor
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Default RE: servo choice for Diamond Dust

I used standard JR-517 BB servos on my first Dust that lasted over 100 flights. My second one had Hitec 425 BB servos and the additional speed and power of this servo was obvious.

It won't be a snare drum since it is sheeted. You might glass the center bottom but save the weight by not doing the top.
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Old 09-09-2006, 11:30 PM
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Default RE: servo choice for Diamond Dust

I would recommend using JR 8611 or HT5955 TG servos if you are planning on running over a 150 mph, that is, installing something more than a sport 46 class motor. I don’t think the reason for this need is the torque that these servos can generate but the toughness of the drive train. I think the vibration of the air pulses from the prop wash just tears them up. Jeff of Diamond Dust personally went out of his way to warn me. “for what you’re going to do, use a JR 8611”.

Ripped from the DD web site:
“Servo Choices = My personal preference for the elevons are the JR/4735's and a micro on the throttle. JR/DS9411 or in an application where you have a monster motor, use a JR/DS8611.For the throttle, the HS85BB is a good choice or the HS81. Note on the throttle linkage, use a plastic clevis at each end and do not crush the grommets, if you do will run the risk of vibration damaging the servo.”
END QUOTE

Yes they are expensive $120 + each. I have well over one hundred flights with the 8611’s and over sixty flight with the 5955 no problems.
It seems like the JR8611’s have better resolution but the HT5955’s are as tight as day one, hard to tell, one sets in a Whiplash and the other’s in a Diamond Dust, call it a draw.


What I won’t ever fly with;
JR ST125 (bought 4 and all made so much back EMF (noise) every receiver I tried fail my range test)
HT 625MG (bought a bunch of these. Some just stopped working in flight[X(], most at preflight. Other maladies poor centering, weak, slow. Because of this I retired the rest.)

JR and HT may have made some improvements or I got a bad batch.

I would like to know from others flying D.D’s ;
(# 1) What speed ?
(#2) What servo ?
(#3) Number of flights? (ongoing or at servo failure).
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Old 09-09-2006, 11:48 PM
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Default RE: servo choice for Diamond Dust

Haveblue, If you make your fuel tank out of epoxy or ester resin it won't hold up for long with the fuel we use.
I've been looking into glassing up a custom tank myself and I wondered if it would hold up if the inside was coated with this stuff:
http://kwikpolyllc.com/
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Old 09-10-2006, 10:28 AM
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Default RE: servo choice for Diamond Dust

thanks for the info guys...I'll obivously have to bench run the engine first to get an idea of what to expect out of this engine although I doubt it will be astounding

the whole reason I sheeted her was for the glassing.. I dont think it's going to add that much weight as the cloth I have is this tissue type weave from a mold maker..its extremely light and the resin is almost the consistency of water..slightly thicker.. but if it fails I'll just build a dust the standard way and cover it in profilm

I can see the logic of getting the 8611's or 5955t but that might be cause for when I get the 60LX

as for the fuel tank I wasn't even thinking that sort of material., initially I just thought of soldering up just a tin one..but that sure is food for thought to make it out resin and then coating it with stuff like in that link...my other alternative is maybe a flex tank and see if I can squash down one corner to make it fit and clear the tuned pipe

should have her done in a week or so..depends how busy I'll be at work...still got to find a new club too so it's not like I have somewhere to fly her when done anyways
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Old 09-10-2006, 10:38 AM
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Default RE: servo choice for Diamond Dust


ORIGINAL: freakingfast

I would like to know from others flying D.D’s ;
(# 1) What speed ?
(#2) What servo ?
(#3) Number of flights? (ongoing or at servo failure).
My first DD started out with a 46FX and UT muffler and ended up with a SJ-50 with the SS muffler. Video timing showed 150+ and theplane had around 125 flights. The crash was not due to servo failure from the JR 517's.

Jett 50 on #2 with the Hitec 425 BB servos. Big difference in servo speed and power and no servo failure but not that many flights.
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