stj7780
Posts: 3
Joined: 1/23/2007
From: Dallas, GA, USA
Status: offline
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First of all I am glad that a nitro crawler is in somebody else’s thoughts besides mine. I started to build an electric version about a year ago and it is almost finished. When I started I hoped that there might be a way to make it nitro but there was not enough info at the time. As for this thread and my ideas here is what I have. Everyone has had some great ideas so far, hydraulic, gear reduction, torque converter, 4 stroke, heli motor and such. These are all awesome ideas. In my line of work I must take diagnose a variety of problems and come up with fixes or solutions on a daily basis. We find that the best solution is typically the simplest solution. That being said here is what I mean.
To use a nitro motor first think of RPM. A typical 55T or 65T lathe motor turns 5500 to 6500 open RPM. Typical nitro .12 or .15 turns 25000 to 28000 rpm. Quick math says that one would need to gear down 5 to 1 to get down to an electric RPM. On top of that most crawlers gear down, on a clod anyway, another 50:1 to 100:1. So the nitro motor needs to be geared down 250:1 to 500:1. The advantages to the extreme gearing are great low speed control. Nitro motors operate from 5000 RPM to 28000 RPM, much better control than 0 to 6500 RPM like an electric. Second is that a nitro crawler would not need a braking system. The drag through a 350:1 gear reduction would be plenty to keep a crawler from rolling while off the throttle. Just as an example this is a 410:1 planetary gear reduction unit for an electric, fairly easy to adapt for nitro use, for $40. http://www.lynxmotion.com/Category.aspx?CategoryID=71
As for cooling, nitro motors for buggies come with substantial heat sinks on the head, we all know this. But at such low load and lack of constant power output, as in crawling, this will limit heat production tremendously. Also one could richen the mixture slightly to keep temp down as well. Might lose some power by doing that but nothing that the gear reduction couldn't cover. One could also use a fan blade style flywheel to aid in cooling as well. I love the idea for heli motor, cooling and clutch setup but it would be so big when done. If one really wanted to use that setup then maybe go with a .15 size heli setup instead.
As for burning up a clutch, one could use a cyntax clutch but I am sure that the low load would not be to hard on a standard shoe.
Fuel tank, defiantly an airplane tank for the rollover capability.
As for a platform, any current TXT based electric would work. Basically you would adapt the nitro motor and gear reduction to a reversing trans, IE TMAXX trans, run revo axles to the TXT axles and the rest is traditional RC Crawler. All of the steering would be the same. Only difference would be the need for a receiver pack to power the electronics.
I hope that maybe this gave someone out there some help. If I had the extra cash then I would have started one but the electric I started is draining me as is along with a boat and a |
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All Forums >> RC Cars, Buggies, Trucks, Tanks and more >> RC Rock Crawlers >> RE: Nitro Rock Crawlers Only 
RE: Nitro Rock Crawlers Only - 
and you should not be asking questions about nitro crawlers you should be telling people how to do it... you could easy get two grand for that thing when its done.... ive seen less go for more...
