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Futaba-RC . Next D . Fast Lad Performance

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Vario Sky Fox - Benzin - Evolution - Xtreme > Gear ratio and clutch help for Benzine Scale that won't fly
 
 
1drummer
Senior Heliman
Location: San Antonio, TX USA

I have a Benzine trainer in a scale fuze swinging 800mm blades, I am having lack of tail control issues and I think one of two things are happening. The tail rpm is not sufficient or the clutch is slipping. I have checked to the best of my knowledge the screw that tightens the clucth down and it is tight, but my core question is; the main gear has 87 teeth and the tail drive gear running off the main has 21 teeth, is that the right gears and how do you calculate the ratios? Also, are there other gears in the mix that I am not using or calculating?
Thank you in advance for any help you can provide to fix my problem.

Richard
04-09-2008 04:57 PM
 
 
helicenter
Senior Heliman
Location: Winter Haven Fl.

ratio

87/21= 4.14x40/23= 7.2

what blades and application are you using this on.?

Doug
04-09-2008 05:52 PM
 
 
1drummer
Senior Heliman
Location: San Antonio, TX USA

I am using the 800mm Vario blades on the Big Carbon Airwolf
04-09-2008 06:18 PM
 
 
marc28
Senior Heliman
Location: new york

you should be using the 90:18 gear set which will give you a ratio of 9.09 at about 1200 rpm. What is your head speed? It sounds like you're having mechanical issues not related to your current 87:21 gear ratio
04-09-2008 06:59 PM
 
 
East Coast Scale
Key Veteran
Location: Taxachussetts

Also, if the clutch is slipping, it would gain rpm and loose head speed.
Joe
04-09-2008 09:28 PM
 
 
1drummer
Senior Heliman
Location: San Antonio, TX USA

I am currently running about 1100-1150 headspeed, when I clear the ground, it will not hold the tail, very sluggish. I don't really hear any increase in motor speed as I would think if it had a slipping clutch.

Richard
04-09-2008 09:58 PM
 
 
marc28
Senior Heliman
Location: new york

You need to change the gear set to 90:18.If you use the 87:21 you are forced to tune and set a low throttle curve to achieve the right head speed.The 90:18 allows the engine to be within it's power band with the right head speed swinging those 800mm blades.I had a serious vibration issue with my huey and did not hear an increase in rpm,but noticed the head speed drop.I had someone tach the head speed as I was setting it up and they noticed the head speed drop. I replaced the clutch with the heavy duty one from the XLV. I don't think you will need to go to the big clutch,I did it because the huey has a working water tank (extra weight)
04-09-2008 11:34 PM
 
 
toejab
Senior Heliman
Location: NEW YORK

I was wondering which engine is in that benzine...the gd23 or the newer G230? and were the original main blades 720 mm and you upped them to the 800mm?
04-09-2008 11:51 PM
 
 
1drummer
Senior Heliman
Location: San Antonio, TX USA

THanks Mark,
You know, I actually thought I was seeing a drop in the headspeed, but I didn't hear the motor doing anything. Maybe the clutch is slipping under load a little??? I will change the gearing to your specs as well, do you think it would spin the motor enough to stop the clutch from slipping with that gearing?

Toejab, I bought this project half done with the present equipment, so I don't know if it originally came with 720's As far as the motor, where is the type stamped? I can't find it....

Thanks
04-10-2008 02:03 AM
 
 
Christopher J
Key Veteran
Location: Kansas City, MO Californian lost in land of Oz

The motor will either be a 230RC or a 260RC. Once you get the right gear ratio in there and achieve your proper headspeed your tail problems should go away.

Christopher J
East Coast Vario Field Rep
"I'm all set"
04-10-2008 06:59 AM
 
 
toejab
Senior Heliman
Location: NEW YORK

he has the red kill switch so i think that would make it the gd23??is that the proper letter id? i have a benzin in route that also has the red kill switch and all wood servo tray AND radio shelf. i am told that they did away with the all wood radio shelf about 2-3 years ago, i have learned a little bit just recently,larry
04-10-2008 07:04 AM
 
 
Christopher J
Key Veteran
Location: Kansas City, MO Californian lost in land of Oz

Very true, I didn't think about the older motors.

Christopher J
East Coast Vario Field Rep
"I'm all set"
04-10-2008 07:10 AM
 
 
marc28
Senior Heliman
Location: new york

Drummer, since you're not sure about the mechanic's history I would check the clutch liner since you're goining to replace the gears.Check it before you order the gears in case you need to replace some additional components.
04-10-2008 02:25 PM
 
 
1drummer
Senior Heliman
Location: San Antonio, TX USA

Thanks for all the help guys,
How can I deturmine what motor I have?
What do I actually look for with the liner? It is a new setup with approximately 5 tanks of fuel through it. As many years I have flown different heli's, I have never had issues with liners, so unless it is physically worn out, I probably wouldn't know what I am looking at. I am also having to get used to these lower headspeeds as I have always run stuff with 1500-1700 headspeeds. I am not complaining, I just feel I am starting over with my being familiar with my equipment.
Thanks again for all the help....

Richard
04-10-2008 02:44 PM
 
 
xcellgasman101
Elite Veteran
Location: WOODWARD, OKLA....

Can you post some pic's??? that might help to determine what engine you have,, XGMVGM

John Crotts
www.soonerhelicamproductions.com
04-10-2008 02:55 PM
HOMEPAGE  
 
 
1drummer
Senior Heliman
Location: San Antonio, TX USA

Sure I'll take some and post.
04-10-2008 03:04 PM
 
 
East Coast Scale
Key Veteran
Location: Taxachussetts

Usually, just above the carb and to the right on the motor under the pull start, on the casting of the motor itself, it tells what motor it is.
Joe
04-10-2008 03:07 PM
 
 
xcellgasman101
Elite Veteran
Location: WOODWARD, OKLA....

Is the Kill switch red, or yellow??? XGM/VGM

John Crotts
www.soonerhelicamproductions.com
04-10-2008 03:13 PM
HOMEPAGE  
 
 
1drummer
Senior Heliman
Location: San Antonio, TX USA

Thanks Joe.
It is red buttons
04-10-2008 06:19 PM
 
 
marc28
Senior Heliman
Location: new york

Change the gears and I think you will be ok.The slippage can possibly be caused by the combination of low throttle curve(engine torque) and blade length(load). If you have the round red kill switch then its the older G23
04-10-2008 06:31 PM
 
 
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Vario Sky Fox - Benzin - Evolution - Xtreme > Gear ratio and clutch help for Benzine Scale that won't fly
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