Help me Daydream, Offroad Hybrid

[CFECO]

You could have a pto shaft off of the front of the engine to drive the wheels mechanically on the fast areas, and 35hp would get you 30mph easily. I'd use a high output MX bike engine, say a YZ 450 4 stroke, 50HP, 8500 to 11,000rpm. Less than 100 lbs.

[P-hack]

well a high rpm motor will only have more losses on the conversion to torqe.

and the hydraulic motors are basically turning all the time, bolted straight to the wheel, so lots of fluid moving around going nowhere at 30mph.

I like hydraulic, as seen on construction equipment and other crawlers (like that thing that moves rockets at 1/3 a mile/hour) but it loses if you want hydraulic energy storage.

An electric motor controller that can monitor current/temperature/etc and minimize breakage isn't that hard to conceive (and liquid cooling can help). But there are lots of design limitations and compromises in that direction as well.

[CFECO]

These are very high efficiency engines withe the torque curve remaining virtually flat from 5000-10000 rpm.

[P-hack]

Smaller engines aren't usually terribly efficient, but there are atv sized rock-crawlers, but how does the hybrid part play along without being the worst of both worlds?

[P-hack]

well this isn't exactly what was described, but an interesting machine anyway, electric drive 4x10hp (peak 200hp total), some large honda generator looking thing, wheelbase can be lengthened/shortened/widened/narrowed/raised/lowered hydraulically. And can go pretty fast, for a little bit.

But it doesn't have much storage, aside from the fuel tank "batteries give it corvette power for 5 seconds". So technically a hybrid (as counting the winch as a hybrid didn't seem to get much traction).

also didn't see any vids of it climbing, mostly dancing around in the parking lot, so nothing conclusive about it performance wise. It might be so expensive he is afraid to climb with it, or it breaks easily, or too heavy with batteries or not geared right for climbing or? But I would think there would be some real climbing vids if it were that good, rather than leave it to your imagination.

green rock dawg

https://www.youtube.com/watch?v=QlaPenxgSvU

[CFECO]

"Efficient", by what metric, HP/CID... In the past a Cox .049 2 cycle won that one hands down, today I don't know. These MC race engines are pretty good for what they are designed for, we now have 4 stroke motors beating two strokes in the same class, and P/W is King!

[CFECO]

Wow, there you go! That looks like the I believe V8 powered machine that each wheel is on an arm which can be pivoted up or down, chain drive as I remember. Articulation is Crazy!

[P-hack]

efficient when discussing an engine can surely be assumed to mean bsfc(well, around here anyway). power to weight can play a role in system efficiency, esp in a vehicle, but an engine by itself cannot go anywhere. The smaller the engine the worse it is at turning fuel into horsepower, typically.

edit, pic:

[TheEnemy]

Here it is in action, way to buisy keeping everything adjusted, more of a can I do it kind of thing. I could see hitting a lever the wrong way and flipping it on its lid.

https://www.youtube.com/watch?v=7GugdJc-O7I#t=121

[TheEnemy]

Originally Posted by P-hack

efficient when discussing an engine can surely be assumed to mean bsfc(well, around here anyway). power to weight can play a role in system efficiency, esp in a vehicle, but an engine by itself cannot go anywhere. The smaller the engine the worse it is at turning fuel into horsepower, typically.

Don't forget extra friction losses due to high RPM. Not to mention I would need at least one extra gear box to convert RPM based horsepower to torque, and I am already geared higher than I like with an engine that can chug along at 500 RPM.