View Full Version : What Motor for a Crazy 8?

11-24-2005, 11:03 PM
I have a Wattage Crazy 8 that needs more power (enter Tim Taylor sound effect here:D). Has anybody else done one of these. I don't really need 3d performance but good verticle would be nice.

I am new to electrics so I need all the help I can get. I have been flying slimers for years though.

11-25-2005, 02:39 AM
I have a Wattage Crazy 8 that needs more power (enter Tim Taylor sound effect here:D). Has anybody else done one of these. I don't really need 3d performance but good verticle would be nice.

I am new to electrics so I need all the help I can get. I have been flying slimers for years though.

I am flying my Crazy8 with a Himax 2025/3200 and a Himax 4.4:1 gear box using an APC 10x7 prop on 1900mAh 3cell LiPos. Very good power. I installed 2.5" wheels to get enough clearance for the prop.
I am changing the gearbox tomorrow to a Cobri 3.4:1 - that will make the Crazy8 scream...:D

If you want to use LiPos you have to mod the fuse in the front. With the LiPos in the battery tray you will not be able to get the CG right. Here is a link to some picture of that mod:

My mod is very similar to that and it works great.



11-25-2005, 04:55 AM
Thanks for the info. Do you have any pictures of you plane with the 2.5 tires. It seems like that big a tire would look a little odd but if it flys good who cares.:D Kind of like a 3D bush plane.;)

11-26-2005, 06:07 AM
Actually they don't look bad at all. here are the pics.

BTW, if you decide to go the gear box path go and get the Himax 2025/4200 or even the 2025/5300. You get more RPM but you need to consider your batteries and your ESC also. But you can run the recomended APC 7x5E prop.
I used the 2025/3200 because I had it sitting in my drawer...

I changed the gear box this evening and will fly her tomorrow with an 9x7.5. If that turns out the way I am hoping for I am going to mount smaller wheels, like 1.5 or 2"

Happy flying.


4149 4150

Jason T
11-26-2005, 01:22 PM
I knew a guy that used to fly a Crazy 8 on a Razor 2500 in a gearbox and it was very fast. I do not remember his gear ratio exactly but I think it was either 3:1 or 4:1.

Matt Kirsch
11-29-2005, 03:56 PM
If you want to go the outrunner route, an AXi 2808/24 with a TP2100 3S pack would be a good choice. That's the choice of many around here with the Eflite MiniFuntana and MiniEdge 540, which weigh around 24-26 ounces.

They list the C8's weight in the 30-35 ounce range, but that's with CP1300 NiCd cells. Mine weighs in at 28oz with a Mega 16/15/5, 2:1 gearbox, and 3S2P Etec 1200 cells. It'd be down around 26 ounces if I switch to a TP2100.

12-22-2005, 03:14 PM
My Crazy 8:

Mega 16/15/5
3s 2100 prolite pack
CC phoenix 25
APC 7x5 eprop
24 amps static


04-05-2006, 08:07 AM
If you want radical power & lots of fun: Axi 2820 10, 40 amp Jeti controler, TP (15c) 2650 3s2p, 11x5.5 pulls right at 400 watts wot., static. (39.9 amps @ 10.1 volts) AUW right at 32 oz.
This is the third setup I've flown in this plane, starting with 7 cell-1400 Ni cads and going to 10 cell-Nimh 1100's, neither of which could provide the current flow needed for more than a few flights before pack degredation. Used the Crazy 8 as a power plant testbed and now moving the winning combo to a new Extreme Flight Extra E300. (used Hitec 55 on the Crazy 8, but went to the 65's on the Extra. Soon to maiden. Had lots of fun with the Crazy 8. (this power pack ROCKETS the crazy 8.)

04-05-2006, 02:00 PM
You got to like the TP 2650 packs. Small and lite and still able to handle 34 amps cont/ 54 burst and still weigh only 168 grams.


Price is right at less than $100.


04-05-2006, 02:24 PM
I have a friend with very dusty Crazy 8 in his shed.

I have offered to rebuild it for him as he is a bit short on shed time lately, and was thinking of trying an Esskay 400XT with an 8x6 or 9x6 prop on 3S LiPo. He doesn't want extreme performance, just a nice aerobatic park plane.

Is the 400XT up to the task or am I dreaming? I would appreciate your thoughts.

04-05-2006, 03:16 PM
I think that your dreaming. I'm seeing that guys are saying that 10 amps is the max draw. That's 105-110 watts max. I love my C-8 at more than twice that. It may fly, but I don't think you'd be happy. If you haven't bought the motor, I'd look at the warp 4 motors and a CC TB 18 esc. I've been eyeing a pair for a Sonic Liner.



04-24-2006, 11:31 PM
Hi All. Not sure if anyone is interested, but I finished installing the 400XT into my friends (Marcus) Crazy 8, not sure what to expect. The AUW came in at 675grams (23.8oz) with an Electric Power 2200mAh 8C 3S pack.

We maidened her yesterday, and I must admit I was not expecting much. With the 8x6 APC prop it took off in about 15-20 feet and climbed away well. Marcus' comment was that it flew better than he remembered with the original powerplant. After a couple of minutes I asked Marcus to land the plane.

I then changed over to the 9x6 APC prop - it leapt into the air in about 8 feet! I'm sure the 9x6 prop is right on the limit of power (I will check it with my Wattmeter today) but it flew fantastic. Plenty of power for aerobatics including rolls, loops, cuban 8's, rolling circles etc (I can't do a rolling circle to save my life but Marcus is pretty good). Of course it won't hover or do any 3D manouvers, but neither would the original setup. When we landed about 15 mins later, the motor and mount were barely warm to touch

:D We couldn't stop grinning:D , as it performed way better than I had expected, even though Motocalc had suggested that it would do well. Landings were a breeze as the reduced wing loading allows you to come in deadstick and flare for a soft 3 point landing. It is not a weapon, but it sure is a heap of fun - the 'Bang for Buck' factor is right up there!

Lessons Learned:
1. Sometimes it pays to have a go, even if you are not sure if it will work.
2. Trust Motocalc more!
3. The 400XT is amazing for it's size, and then some more when you remember it cost less than US$20!

04-25-2006, 02:10 AM
I have just connected my Wattmeter and got a bit of a fright.

On a freshly charged 3S pack at full throttle with a 9x6 APC prop it is pulling 12.7A and 142W peak! The bottom cowling is missing from the Crazy 8 which would help cooling I guess, but it was barely warm after flying yesterday. I think I better keep an eye on the temp in the next few flights.

Any comments?