JR8717 servos in 90SE

[Helisrfun]

Has anyone installed the JR8717 servos in the Raptor 90? They look like there going to fit very tight and was wondering what the fix was to get them in. I havent found anything on this issue yet and didn't want to force them in. Anyone?

[vandelescrow]

Check out this thread http://www.helifreak.com/showthread.php?t=55648

[Helisrfun]

vandelescrow,
Hey thanks again for the input!:lol: I have been told with other heli builds that you should have some space between the servo and the mounting frame for vibration isolation or to minimise it at least and case binding issues. Since there aluminum housings I guess there wouldn't be a binding issue.
So to recap you installed them in the servo tray without any modifications?

Thanks, Helisrfun

[Ah Clem]

helisrfun,

I realize that you addressed this to Vandlescrow but...

The 8717's in my ship were an interference fit-the servo, with its aluminum case, is approximately 1mm larger in all dimentions than standard. The servo case touched both sides of the servo tray.

I did grind out the servo trays to provide clearance all the way around.

As much as these servos cost, and as much is at stake, expense and safety-wise, with a 90 sized ship, I saw no reason to subject the servos to uneccessary vibration.

I was very impatient, and wanted to get my machine in the air, but decided to do what I thought were "best mechanical practices".

Just my 2 cents,

By the way, these .90 sized Raptors fly beatifully. Sort of unbelievable they fly so good.

[Helisrfun]

Thanks Ah Clem, I'm going to make some room where ever I can. I hate to have things shoe-horn fit when there not suposed to be so I'll go at it with my dremel tool. Speaking of shoe horn fits I'm having a heck of a time getting the plastic flex bearing holders on the torque shaft for the tail rotor installed into the tube. Any sugestions?

I have been told numerous time now how good theese fly and can't wait to try it out but living in the North East this time of year and the way we have been getting slamed with the snow this year it may be some time untill I actually get a chance. :bawl

[vandelescrow]

I followed the directions in the manual and I had one of the bearings come loose on the torque tube when I inserted it in the boom. I already had zap a dap a (what ever) glue on the first one and already in the boom so I had to go for it and finish the boom. I recomend follow the directions in the manual but add a small bead of CA next to the bearing to help hold it in place when sliding it into the boom. Make sure you don't bet any in the bearing.

When inserting. I got a few of the flanges started, then slowly rotated it and pushed the next flang in as it got to the slot in the boom (front end of boom). Once all the flanges on the leading edge were started I put the zap a dap . . . around the outside, slid it in, the second set of flanges go in real easy. Then the same with the second bearing but this is the one that came loose on me. I added the glue and used a spare piece of threaded rod to get it down the boom about 10 inches. 12 inches would have been ideal but I had nothing available. Before the glue dried I then put the tail assembly on the boom and pushed the torque tube till it stoped. I then removed the tail and moved the torque tube back about 1/8th inch so it wouldn't bind the tail.

Long story but in short, when your done the torque tube protrudes from the boom on both ends the same amount.

[Ah Clem]

Vandlescrow,

I had virtually the same experience when installing the torque tube drive, including one of the bearings coming loose on the drive shaft.

Next time, I will attach the bearings to the drive shaft with JB Weld, let it dry, then insert the whole thing into the boom.


By the way, did either of you do the mod for retaining the pins through the tail drive gears that has been mentioned on Run Ryder? I took brass tubing, cut it into thin rings, and epoxied it (JB Weld again) around the nylon drive gears where the pin goes through.

There are numerous stories of the pins moving out and jamming things or falling out completely.

Either way, it ruins your entire day.

http://www.runryder.com/helicopter/t392496p1/?highlight=pin


I am actually considering purchasing an entire new tail boom, with drive shaft and both gear boxes and building it up as a spare. Eventually I will crack this thing up, and that is a reasonably time consuming part of the assembly process (assumig you make the rings described above, etc.).

[vandelescrow]

Thanks ah Clem, I did not know about that. Also Goebee makes a belt conversion for the Raptor 90 that looks really nice. "Beast" was going to do a test to see if torque tube or belt takes more power from the engine. I need to check with him on the results.

[Ah Clem]

Vandlescrow,

I am very curious about the belt conversion.

I know that the torque tube drive is technically better, in terms of less drag, etc., but I always wonder how much difference it really makes.

All of my .50 size machines run belts. They are easy to install and repair, and are very inexpensive.

I can remember sticking the tail in the grass with the Heliboy years ago, an the main gear would be instantly gone (geared, wire tail drive).

[vandelescrow]

Ah Clem,

I just got a reply back from "Beast" but he has not had the time to do the testing yet on the torque tube vs. belt. One thing about the Goebe convertion, the write up talks about there main gear will not work with the stock Raptor autorotation hub due to it having 6 bolts vs. the Raptor 4 bolts. I e-mailed them quite along time ago asking if the Raptor main gear will work with there conversion but never got a reply. It was back during the hight of fly-ins and good flying weather so the e-mail probably got sliped throught he cracks.

Has anyone here done this conversion? http://www.gohbee.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=GB111&Category_Code=1110

[spames]

I have a XeroG conversion kit for my Raptor 50 v2 and have installed the JR8717 servos. I have only hovered and light FF and she is very snappy. So far I like them. Going out today and give it a good test flight. I will let you know later today how she flies with this set up.

[Ah Clem]

spames,

I am interested in your report on your machine. Please post when you have flown it.


Vandlescrow,

How close is your ship to flying?

I am still nervous with mine, due to the expense involed in reparing it, but it flies really well.

[vandelescrow]

Still need blades, throttle servo, receiver and muffler. Should get my income taxes back any day now so it wont be long. I'd guess 1-2 weeks.