What type of engine is small but very powerful?

Question

it has to be at least smaller than 2 by 8 in

Answer 1

If you have a source of power:

Steam motors/air motors can deliver massive amounts of power for their size, but at very high speeds. If you are looking for raw torque a small hydraulic motor would be ideal. A 2"x8" DC motor could also be quite powerful.

If it has to be portable:

You can get 2"x8" electric motors that are very powerful. The problem is you need a big battery, a lot bigger then 2"x8". You won't get much of a powerful motor/battery combo in such a small space. You could use super/ultracapacitors to power a large electric motor for a short period of time. How about a rocket motor? Maybe a small model car engine?

If this is for a helicopter the best conventional power/weight ratio is going to be a 2 stroke gasoline engine. Check out rotax engines if you have the cash. If not cut up an old dirt bike engine. Anywhere from a cr125(15hp) to a cr500(55hp). You can double this with performance parts but risk an in air failure.

Then there is the exotics like a hydrogen peroxide turboshaft engine which have the capability to deliver ridiculous amounts of energy for their weight. You defiantly need to be retired with a CNC machine and a lot of cash to venture down that road.

Answer 2

well with that size as a constraint the a DC powered electric motor would be the only option.

Answer 3

At that size it would be a electric motor.

Answer 4

wankel engine is the smallest and the powerful engine.

check it out in this link

http://en.wikipedia.org/wiki/Wankel_engi...

Answer 5

Try a model airplane engine

Answer 6

If you put more information in the question, posters will provide answers that are more on target.

From your previous question, looks like you want to design a 100 lb helicopter.

There are two ways to design things: use the theory and do lotsa calculations, or compare existing designs and use typical values. That's what I'll do here.

First, you will get at best 50 lb payload for about 50 lb of chopper.To lift a chopper, you need about 10lb/hp weight, so you need about a 10HP motor, and it's weight budget is about 2lb/HP, or 20lb. Weed wackers have 1 - 2 HP, weight 2 - 5lbs. Not enough power. Chain saws are a little bigger, maybe 5 or 6 HP. A little too small, and I hate 2cycles. Lawn tractor engines for 10HP are 130+ lb, way too heavy.  I'm thinking small 4 cycle motor cycle engine is your best bet. A Honda 50cc probably runs about 7 HP, so a Honda 70 should about do it, a 90 should have some extra. Don't know what the weight difference is between the 70 and the 90, or how hard they are to get. Some of these types of engines use similar parts, just change the piston diameter or stroke a little to increase displacement.

A 500 lb chopper has about 250 ft² of blade area. So, yours should require about 50 ft². Now, there is some scale factor, so let's go 70 ft². For a round rotor, this is a blade diameter of 9 to 9.5 ft. Tip speed should be about 400MPH, so 1200 RPM or 20revs per second. About 60MPH of lift or 88 ft/sec should do it. Dividing through, need up to about 4ft per rev, but pitch needs to be adjustable down to zero.

The engine likely revs up to about 10,000 RPM, so need 8:1 or so gear reduction. The transmission that comes with it should be able to do this.