View Full Version : X-Cell Gas upper frame doubler

06-24-2004, 08:03 PM
Miniature Aircraft has long recommended the use of aluminum upper side frames when using the gas machine for heavy lifting or camera work. I have discovered that the power of the G-231 will also stress the upper frames and the added power also "tweaks" the upper frames enough to cause rapid main gear wear. This mis-alignment also robs power from the head and can lead to bearing failures as well. I recommend that the doublers be used when running a G-231 (or G26 :puke ), especially for 3-D.

Part of the problem is the upper area forward of the upper main bearing cracking from the stress. The frames also can flex allowing the gear mesh to be disturbed from torque.

A simple upper frame doubler can be easily made and installed in less than an hour, which will tighten up the flex and add integrity to the area just under the upper main bearing block. After making this set of doublers, I immediately could tell a big difference in useable power to the head when pushing the machine. This is due to the main gear/pinion staying in proper mesh and not consuming power that is then tranferred to the head. Viola!.... Instant power upgrade!

Use a set of broken frames from a ST, CT, SE, etc. or even an old set of bent (single) frames. Cut out the upper area from behind the main bearing blocks to the front of the frames and use these as doublers. Make sure to use all of the tops as shown in the pictures, as this will capture the main blocks, start/clutch stack block and tie up into the front of the frames.

BTW. Use extreme caution when cutting any carbon fiber. The dust from cutting or grinding is very harmful to breathe! Use a respirator when doing any carbon cutting/grinding.

Use a drill, and open up the hole for the bell crank pivot so that the doubler will slip over the pivot without removal. The bell cranks will need to be temporarily removed though. Depending on the frames you cut your doublers from (I used a bent frame set), you may have to open the upper bearing block holes upward a bit to get the holes to line up. This is because the upper bearing is a bit higher on the gas machine than the original X-Cell bent frame model. It may also be neccessary to elongate the clutch bearing block slots in the doublers also so that it will match what you have on the gas machine. Use longer bolts when you bolt in the doubler as there is more thickness to pass through. Set the gear mesh and you are done!

Later! :glasses2:

06-26-2004, 08:43 AM
Hi John,

I did basically the same thing, but with aluminum and only between the upper and lower bearings.

I haven't figured out how to include a picture from my gallery yet, so just click here to see it:


I have one of these on each side of the heli. I did this as I found that the small area in the corner where each bearing is 'contained' is a weak area which I have seen fail due to vibration, etc. I never thought the main gear needed reinforcement too.

I showed this to MinAir and they commented that it should do the trick for reinforcement.

I asked MinAir why don't they simply sell a doubler instead of forcing people to totally replace the upper frames. It's easier to add a doubler than to take everything apart to do the replacement 'upgrade'. I guess they didn't want to recreate a part, it's probably easier for them to sell the aluminum upper frames than to make a 'doubler' kit.

06-27-2004, 08:48 AM
There is a very good benefit from doubling all the way up to the front of the frames. As I said, it ties the "drive components" together so that the gear mesh does not get torqued out of alignment. The other benefit is just as you describe. I have spoke to Tim about this mod and he said it would be easy to make up a set. Of course time is the biggest problem. The man is extremely busy and must prioritize his time as much as possible. Who knows, he may get around to making one up.