I’ve got 5 little tiny airplane engines lying around here, and one of them has an adjustable throttle. It’s called the ENYA 19-V Model 4005. I looked up specs and found out it has .38 BHP at 13000 RPM, which equates to .15 ft/lbs or 1.8 in/lbs. So with a 1:13 gear reduction, that means 23.4 in/lbs of torque at the wheels at 1000rpm! I would like to mount it to vex parts and have a neat dragster. Any ideas for what I should do would be appreciated. So far I’ve got:
Some sort of clutch so I can disengage to stop it without shutting off the engine. Thinking a normal friction clutch used on cars.
Tiny ball bearings, 13000 rpm is way too much for those plastic things.
Not sure if i should go with my own gear system, or will vex’s high-strength gears be strong enough? Thinking a 1:13 ratio, so 1000rpm at the wheels. 5" wheels= about 21 ft/s.
Gear housing for safety. Kudos to gblake for that idea.
Please I don’t want any comments telling me not to do this because its overkill or its blah blah blah. I don’t care, I’m trying it no matter what you say.
Just use the right parts for the right job and you won’t hear those comments.
For example, when you are picking the shards of gears out of your eyes or flesh, use a sterile tweezer; and when you are dressing any wounds, use tape or other adhesives designed for that job, not duct tape. When the doctor dresses them properly later, you won’t enjoy having duct tape removed.
I didn’t follow how you jumped from 1.8 in-lbs at 13,000 RPM to 23.4 in-lbs at 1000 rpm. Can you supply a few more details on what you have in mind?
I think it all depends on how the mount on the front of the engine is. What I would try doing is getting the 12 tooth metal gears and stacking like 3 or 4 of those on the shaft of the nitro motor. (Securing them for such a high speed may be hard). These gears would drive 3 or 4 giant gears (like 84 teeth I think is the biggest). That is a huge gear ratio and should drop the rpm to a few thousand and from here a small gear ratio can drop it even lower to be under 1000rpm.
If you could post pictures of the engine that would be great.
However I do see a problem with using an airplane engine, at low rpm’s they don’t have much power and can be easily stalled so I think you would have to devise a clutch system to rev it up and then engaged the wheels. This makes me doubt that you can use these I mean no vex constructed component is going to be able to act as a clutch for a multi thousand rpm high torque engine. Vex was never designed to handle these rpm’s and speeds which is asking for trouble, at 30mph the shaft collars will come undone and your robot will get messed up really bad after it crashes.
The engine will always be at 13000 rpm unless I’m stopped and it’s idling. I crunched some numbers, and found that a 1:5x1:5 will drop rpms down to 520, and 1:5x1:5x1:5 will drop to 104 rpms. The engine will hold the gear on with nothing but pressure, it’s designed to hold propellers on that way, and the nut tightens with the force of it spinning. I’ll post some pics in a minute.
A bit of realty is need here, one the fuel will dissolve most plastics, two the vibrations will tear your robot apart if you do not lock all screws, and three Vex shafts will not take that kind of torque. Oh and check your health insurance be for you start that motor in a Vex robot as you will need it!
forgot to tell you you will need to replace the cylinder head with one for use in RC cars, they have a much bigger heat-sink, or you could go water cooled but that would add a lot of wight. I have made several car-type steering robots and none of them would work at high speed, to much slop. Your best bet would be something like an air-boat with wheels. You should go talk to someone in a Hobby shop that has RC. Fuel will come out of the exhaust.
I just don’t see a point in putting this motor on the vex robot, if you can’t devise a clutch system then really what is the point because the wheels would rotate constantly
BINGO I just had an idea, if you can hook up this motor and gear it to an axle like you were talking about then you could use a third wheel with an electric motor to prop the drive wheels off the ground. Then you would just reverse the motor and the prop would raise up and the drive wheels would touch the ground. This is the only way that I can see it working as a stop and go robot.
If you get this to work then make a full youtube video of it, I would love to see a nitro engine on a vex chassis :eek:
And your idea just gave me one - Many industrial machines use high-efficiency fossil fuel motors to generate electricity, and then use the electricity to carry out the machine’s real purpose. This decouples the fossil fuel engine from much of the variablity in the machine’s operating environment.
If you hook your airplane engine up to many types of electric motors, you can use them to generate electricity rather than consume it…
PS: Don’t forget the previous admonitions about using sterile tweezers to pluck pieces of shrapnel out of observers, and about avoiding using duct tape to dress a wound.
i like this idea a lot.l i am currently making a decent sized wind turbine for my house. this seems like an awesome project you could make your own alternator with magnet wire and spin up some magnet rotors with the airplane engine and charge up some batteries to run a bot. way cooler way more safe. this takes my vote.