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Apr 19, 2002, 05:39 PM
Thread OP

CrazyMax with 400 ready for test flight.


After crashing my CM again, and having the firewall loose for the 4th time, I thought why not try it with more power? (grunt)

I had a 400 with a 1.7:1 gearbox laying around, so I ProBonded two 1/8"cf tubes to the inside of the fuse and strapped the motor on with rubberbands (and a tie wrap, added later). Just used TLAR standards for the down and right thrust.

Had to lengthen the landing gear legs to let me try larger props. Cut the original legs in half and stuck them inside of 3" long cf tube, also used the same tube for the axle.

For the landing gear mount I put one of the old mounting screws in the bottom and a cf peg in front under the motor. The screw keeps the gear from going forward and rubberband holds it from moving back. Or hopefully will let go instead of breaking in a crash.

Planning to start with a GWS 9x7 prop, also have a 8x6", 9x4.7". and a 10x4.7 already drilled out to fit the hub.

Am hoping to get first flight tomorrow morning.

Think it will work??

BC
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Apr 19, 2002, 06:21 PM
Oh yeah!
Apr 22, 2002, 12:50 PM
Thread OP
Well, got to try the CM today, flew good but the 9x7" prop is too much, the 8x 5/4AAA 800's lasted about 5 minutes and were hot and the motor was hot. Good speed, a little slower than stock but more responsive. Rolls seemed tighter, loops not as tight. The CG may be a 1/4" farther up.

Will try again with the 8x6" and hopefully pick up a 7x6" or even a 6x5".

Only managed a little carnage when the second battery ran out while inverted and I thought I still had enough altitude to flip over. Almost Only popped the wing off.

BC
Apr 22, 2002, 01:47 PM
BC, I reckon you'd be much better off with 8x500ar or 8x600ae cells, I really can't see those NiMh putting out 10 amps and not have a severe voltage drop under load.
I've found that stepping up to these nicads gives a noticable increase in performance over 5/4aaa size Nimh even with the inreased weight...
Apr 22, 2002, 04:08 PM
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Ben74's Avatar
good idea. i was thinking about doing the same with my CM, if i ever get bored with it. i would use 500ARs though. the stock NiMHs get damn hot even with the 370. they shouldn't be used for speed 400s.
Apr 22, 2002, 05:03 PM
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mattk17's Avatar
I agree with earlier post. The nimh cells probably are the limiting factor on a speed 400 even if it was geared. I'd try it with a 8-cell 500AR and I bet you get 4-5 minutes of wing ripping torque. For even more excitement, try a direct drive 400 on there with a zagi prop!
Apr 22, 2002, 05:55 PM
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Ben74's Avatar
OMG! i think a speed 400 direct drive would tear this plane apart! it would be fun to watch tho...
Apr 22, 2002, 07:20 PM
Thread OP
I probably should have mentioned that my other packs are 2/3A 800mah NiMH. I know they still don't deliver the amps that a Nicad can but they do work better thant the 5/4's.

Quote MattK17 "wing ripping torque"

I really like the sound of that!

I guess I'll have to get some 500AR's to try out.

I have to agree with Ben about the DD, that would be the other kind of "wing ripping".

It was a lot of fun to fly today with more power and less speed. It didn't seem nearly as twitchy as usual. Maybe just because of the more forward CG.

Did you guys see the thread about the Cap & Katana from VerticalRC? Man, I might have to buy one of those and swap this CM stuff over! Outrageous A possible worthy successor?Cap thread

Thanks,

BC
Apr 22, 2002, 08:34 PM
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Ben74's Avatar
all this talk has got me thinking. i'm going to go on a quest to make my CM hover. i just want to see what it's like

i saw some earlier posts about using the GWS 300 motors on the CM. apparently, they are very easy to mount in place of the stock 370. with a high ratio gearbox (~6.6:1) and the right prop, i think this plane may be able to hover using my 720 NiMHs. pitch speed will be low, but who cares? i'll let you know how it goes.


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