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Ace Hobby . Esprit Model . Thunder Power RC

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JR Heli Vibe - Airskipper - Sylphide - Venture > Vibe 50 Throttle Servo Choice
 
 
Blade_Master1
Key Veteran
Location: Canada

your collective was faster than the engine so whats the point of putting fast servos on the collective/cyclic if the engine can't handle it

I've got hs5625's on the collective/cyclic and a crappy fast bluebird on the throttle now the acceleration is quicker then the collective now I have very little bogging on the engine since I changed the throttle servo




JM2C's :)
09-15-2008 04:01 AM
 
 
Eury
rrProfessor
Location: Ankeny, IA, USA.

I've flown numerous servos on throttle in the same heli, and there is no reason to put something like a 9254 on it. If anything, the 9254s hurt, it would burble for a fraction of a second when I'd punch the collective, where a bit slower servo is smooth and doesn't have that burble. My HS81s are spec-ed at .09 on 6v, and work perfectly. In the air, there is no difference in performance between the HS81s I use now and the Futaba that is around .18 that I had in my Vibe while waiting for the adapter plate for the 81.


Nick Crego
Still wanted by the government, I survive as a soldier of fortune.
09-15-2008 04:04 AM
 
 
Blade_Master1
Key Veteran
Location: Canada

Can someone answer this

Quote 
so whats the point of putting fast servos on the collective/cyclic if the engine can't handle it

JM2C's :)
09-15-2008 04:15 AM
 
 
Eury
rrProfessor
Location: Ankeny, IA, USA.

Why do you think they have any relation? As was explained above, the sweep of the throttle servo is tiny compared to how far the swash servos have to move, it's somewhere in the region of 3 to 1. So, a servo rated at .10 on the swash is moving 60 degrees, you are only going to need a servo of .3 on the throttle to match that performance on the throttle.


Nick Crego
Still wanted by the government, I survive as a soldier of fortune.
09-15-2008 04:20 AM
 
 
Blade_Master1
Key Veteran
Location: Canada

Eury

so your saying the collectve moves 3-1 to the throtle

so the collective has to be 3X faster than the throtle servo ?

JM2C's :)
09-15-2008 04:29 AM
 
 
Eury
rrProfessor
Location: Ankeny, IA, USA.

Those numbers aren't measured, just ones I'm pulling out of the air and other posts, but yes, if you want the speed of the 2 to match, then yes, your swash servos have to be faster. It's not going to hurt anything to have the throttle faster (up to a point), but the actual distance and load that the throttle servo has to bear is much smaller than the swash, so the throttle doesn't have to be anywhere near as fast as the swash servos.


Nick Crego
Still wanted by the government, I survive as a soldier of fortune.
09-15-2008 04:32 AM
 
 
captrlp
Senior Heliman
Location: spanish fork, utah - USA

As mentioned, the barrel can move as fast as you want, but the engine can only respond "so quickly". Too fast on the barrel and the engine will "burble" or hiccup.
Find an older vehicle with a carb and manually throw the barrel to different positions as fast as possible, the engine will not respond in a smooth fashion. Same philosophy on the helis.
Although the 8417 is rated at .10 @ 4.8 and may be on the high end of the necessary speed, it shouldnt cause the engine to hiccup.

take care, dont step on the toes today that may be connected to the butt you have to kiss tomorrow!!
09-15-2008 04:35 AM
HOMEPAGE  
 
 
Blade_Master1
Key Veteran
Location: Canada

Hmm ok so it's not related to the collective then

the servo needs to match the engines acceleration curve.

that makes more sense

so my ds821 @ 0.18 was probably slower than the acceleration curve on my OS37 so when I switched to a 0.13 it matched the curve better

JM2C's :)
09-15-2008 04:40 AM
 
 
Pinecone
Key Veteran
Location: Maryalnd

I am running a DS3517 on mine. I wanted digital for precision, and it was the only JR digital mini I could get quickly.

Terry
Blade CP
Trex 450 SE
QJ EP8v2 EX
Gaui Hurricane 550
Vibe 50
09-15-2008 06:05 AM
 
 
Fastsrt
Senior Heliman
Location: Old Hickory, Tn.37138

Futaba 9452 for throttle here. Plenty fast at .11

My 600N's have HS-81 and have performed very well also.

2 x Synergy N9's, T-Rex 700, Trex 600N, Vibe 50, Trex 250
09-15-2008 06:12 AM
 
 
3Dx
Key Veteran
Location: Monterrey NL Mexico!

JR DS285, no problem at all!!



I just order some of this as well.

DS287MG Digital Ultra Speed Sub-Micro MG SX
Size Category: Minis and Micros
Type: Digital
Torque: 13 oz/in @ 4.8V; 16 oz/in @ 6V
Speed: .08 sec/60 @ 4.8V; .07 sec/60 @ 6V
Dimensions (WxLxH): .45x.87x85 in.
Weight: .4 oz
09-15-2008 06:29 AM
 
 
Wingman77
Elite Veteran
Location: Pulaski TN US

that is what I would like to get-ds285
09-15-2008 02:11 PM
 
 
Zaneman007
Key Veteran
Location: Texas - USA

I just slapped a HS81 on my throttle. I hope it holds.

I'd rather be flying
09-15-2008 06:50 PM
 
 
erl919
Heliman
Location: Philippines

I used HS82MG on mine and it fail. Throttle stuck to half. waited for the fuel to run dry and landed safely.

Three HS82MG failed in our group already.
09-27-2008 05:14 AM
 
 
MolokaiBoy
Key Veteran
Location: Kailua-Kona,Hawaii USA

Quote 
you want your throttle servo to be faster than your collective .

So if I am using JR8717 on collective what throttle servo should I be using?

I am currently using a 9252 and works great!

Les
Big Island RC Helis
09-27-2008 08:26 AM
HOMEPAGE  
 
 
BarracudaHockey
rrMaster
Location: Orange Park FL

If it works great then thats the one you should be using.


AMA 77227
http://www.jaxrc.com
09-27-2008 12:47 PM
 
 
KevinB
Senior Heliman
Location: Saskatoon, Saskatchewan, Canada

I wouldn't have believed you could have too fast a servo .....but on throttle you can.
When I first built my Vibe, I put an 8717 on the throttle as well. It flew ok, but after every flight I had drops of raw fuel on the sides of the cooling shroud. Between being rich for the engine breakin and the speed of the 8717, the engine was actually 'puking' raw fuel out the carb barrel during fast load/throttle changes.
I changed the servo to an 8311, hs65MG, and now a 3400G, and no more fuel on the shroud for any of them. The 3400 isn't a lot slower than the 8717. @ 4.8 its rated at .11 where the 8717 is .09, however the 3400 likely is closer to .12 with the load of ball link & carb barrel friction where the 8717 doesn't slow down for much. From this it seems the engine is capable of handling up to around .11, but .09 or faster is counter-productive. For reference, I'm currently running a ys50 with a MP5SB and the 3400G. At the time of my testing the different servos (8717,8311,hs65mg,3400G), I had a SAB-50-3D muffler on.
FWIW.

Kevin
09-27-2008 03:34 PM
 
 
Goose(is dead...)
Senior Heliman
Location: UK

The ATG solution

This is the whole reason CY invented the Active Throttle Governor (ATG). It considers both your pre-programmed throttle curve and your head speed. It balances between the two for optimal response.
09-29-2008 08:55 AM
 
 
BarracudaHockey
rrMaster
Location: Orange Park FL

Nothing new there, according to Colin the CSM's take the throttle curve input, the sensor input, compute the difference and make corrections. The closer the throttle curve, the less difference, and the better they work.


AMA 77227
http://www.jaxrc.com
09-29-2008 12:23 PM
 
 
KevinB
Senior Heliman
Location: Saskatoon, Saskatchewan, Canada

I don't believe the ATG, or any other current governor on the market, optimizes to the point of correcting for throttle servo speed versus what the engine is capable of responding to ? If any governor senses the RPMs falling below target, it's going to give more throttle. If the engine chokes on extra fuel because the servo opened the barrel so fast it couldn't use the fuel quick enough, the gov will give even more throttle to correct the even further decayed RPM.....won't it ?

The speeds of servos we have today were reserved for only high end gyro combos just a few years ago. I don't know if the gov manufacturers have taken that into account yet. Does the ATG or any other gov currently on the market have a menu setting for the specific throttle servo model ? ( like the Spartan gyro has to optimize tail rotor control .....so that the device knows what it has to work with as far as servo speed. ) Please correct me if I'm wrong about the ATG. I've never used one.

Kevin
09-29-2008 01:57 PM
 
 
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JR Heli Vibe - Airskipper - Sylphide - Venture > Vibe 50 Throttle Servo Choice
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