Let's discuss alternative engines!

[Kaveman]

The link to AIE can be found on the Badlands engine page, as I'm sure you all have looked and drooled. Then you saw the price! 17k+
To be fair, I contacted them about seven years ago, and the quote was 16k, so inflation hasn't hit them too hard, apparently. Needless to say that large RC project ended up electric.

Ten years ago, I was a moderator for a motorized bicycle forum, of all things, and a topic of great interest was a "new" rotary engine from a company called Liquid Piston. Essentially is an inside out Wankel, where the rotor is an oval and the housing is the magic Dorito shape. Allegedly scalable from 3-300 horsepower, multi fuel capable, low vibration, low noise, you name it, they claimed it. They even had a working engine in a go-kart as a demonstrator. Well, they did land a DOD contract. They build APUs, Auxiliary Power Units, for tanks and artillery pieces. There must be something there, right?

You can buy liquid piston stock, you can even invest in the company directly, but they have yet to answer my emails. As far as I can tell, their engines are not publicly available. I sent new email to the contact info on their website a month ago, nothing. My disappointment is palpable. I can't even find out if it's just too expensive to bother with, like the AIE unit. I can't imagine that the DOD decided to mount $17,000 generators to the side of multimillion dollar tanks and howitzers, but I've seen the US military pull some insanely stupid stuff.

[Mountain Cat]

Ultralight engines are never really going to have a long life span (TBO). They are run in the higher RPM range most of their life in unbearable conditions(high heat) and are mistreated by the owners. A two stroke engine can survive in these conditions for 300-500 hrs or so. Most 4 strokes will self-destruct in half that time running in the same conditions. Of course, there are exceptions to most everything. It will be interesting to see how many hrs the Thump-Air goes before complaining. A Polini running at 8000 RPM can go 150-200 hrs before parts need to be replaced and good for another 200 hrs or so. I have no doubt that with proper care, it will make it to 400 hrs. We keep looking for a "add gas and go fly" engine and it probably won't exist without a hefty price tag.

[Kaveman]

While "Add gas and fly" would be nice, I've never smoked anything that would make me dream that big!

It's not that there's no alternatives out there, it's just most are far too heavy. I pointed out the two rotary engines I knew of first, because I know they list great power to weight ratios.

The thump air is promising, but it really is just a built up Honda clone. Those things were designed to run generators, not fly. If we're going to get excited about that, maybe we should look at some of it's competition, like the Kohler and Kubota small diesels.

Perhaps since the STOL drag guys seem to like snowmobile engines, maybe there's a motorcycle powerplant out there just waiting to be flown.

Maybe the question I need to ask is, just how much horsepower is enough? Let's just say for our gross weight? How much woopow do we need? If it's all about torque, maybe we really should be thinking about diesel?

[Mountain Cat]

I've always thought that there was a cycle engine or ATV engine out there that would make a dandy UL engine. Many have tried and failed but the hunt goes on. Most of the new ideas are coming from across the big pond now. The Polini, the RMZ 500, and a few others. But there isn't much return on investment for a dedicated UL engine. So most have to develop a multi use engine. We are all chasing that mystical perfect engine.

[Badland-F5 Pilot]

While "Add gas and fly" would be nice, I've never smoked anything that would make me dream that big!

It's not that there's no alternatives out there, it's just most are far too heavy. I pointed out the two rotary engines I knew of first, because I know they list great power to weight ratios.

The thump air is promising, but it really is just a built up Honda clone. Those things were designed to run generators, not fly. If we're going to get excited about that, maybe we should look at some of it's competition, like the Kohler and Kubota small diesels.

Perhaps since the STOL drag guys seem to like snowmobile engines, maybe there's a motorcycle powerplant out there just waiting to be flown.

Maybe the question I need to ask is, just how much horsepower is enough? Let's just say for our gross weight? How much woopow do we need? If it's all about torque, maybe we really should be thinking about diesel?

I have to disagree. Scott has put a lot of effort into modifying the engine to be much stronger and lighter than the original design. Scott has a very nice shop and machines many parts for the engine to enhance it. I've seen the conversions in the past, and most are not much more than motor mounts and brackets. With the new wave of 4 stroke conversions, there's much more engineering going into the conversion. I could be totally wrong on this or this is just wishful thinking, I guess we'll all find out in the next couple of years if we have something new or that this is all a wash, rinse, repeat of the past modified engines of promise.

Todd

[Kaveman]

Todd, I built the 350 small block in my suburban. I used quality parts, many aftermarket and performance modifications, etc. It did not magically become a "Kaveman 350" it's still a small block Chevy, and still has all the inherit issues of a pushrod V8.

The thump air is a very nicely built Honda clone. Thinking otherwise is deluding yourself. If I take the engine off my log splitter, pull the shrouds off and throw some shiny at it, you'd never know the difference, just sitting there. I'm sure Scott has done a lot of work, but I'm also sure that the engines are meant to run generators and water pumps etc. They are designed to be stationary engines, and start doing silly things when you put them on a go-kart, let alone an aircraft. How has Scott solved the oiling problem? That's an issue that has to be dealt with as soon as you bypass the governor and push on 4,000 rpm. That's what that thing was designed for, 4k, sitting still, making air, or moving water.

Why is the VW bug so capable off road? The nazis designed the suspension to support a machine gun turret on the top. That's why the old bug can run the Baja 1000 basically stock, and a Geo Metro can't make the start line. Just because Scott has put a lift kit on a metro, does not a Baja Bug make.

[Mountain Cat]

I wish Scott the best and hope it's a big success. He has put in the time and effort to make it work. Same as Chris has put in with the Badlands.

[Badland-F5 Pilot]

I wish Scott the best and hope it's a big success. He has put in the time and effort to make it work. Same as Chris has put in with the Badlands.

Exactly. After speaking with Chris on our last virtual fly-in I have much confidence in the work he's put into the engine. I rebuilt the engine in my 73 Chevy Vega and made that little 140cc 4 banger sing. Friends and I built engines and drag raced in high school. Those engines were street drivable, lasted almost identical to a stock engine, and yet put out a lot more power. We also went to The Tripple M Raceway a lot.

It all comes down to deciding what you wish to do and how you're going to get to that goal.

Todd

[Badland-F5 Pilot]

Todd, I built the 350 small block in my suburban. I used quality parts, many aftermarket and performance modifications, etc. It did not magically become a "Kaveman 350" it's still a small block Chevy, and still has all the inherit issues of a pushrod V8.

The thump air is a very nicely built Honda clone. Thinking otherwise is deluding yourself. If I take the engine off my log splitter, pull the shrouds off and throw some shiny at it, you'd never know the difference, just sitting there. I'm sure Scott has done a lot of work, but I'm also sure that the engines are meant to run generators and water pumps etc. They are designed to be stationary engines, and start doing silly things when you put them on a go-kart, let alone an aircraft. How has Scott solved the oiling problem? That's an issue that has to be dealt with as soon as you bypass the governor and push on 4,000 rpm. That's what that thing was designed for, 4k, sitting still, making air, or moving water.

Why is the VW bug so capable off road? The nazis designed the suspension to support a machine gun turret on the top. That's why the old bug can run the Baja 1000 basically stock, and a Geo Metro can't make the start line. Just because Scott has put a lift kit on a metro, does not a Baja Bug make.

You may wish to talk to Scott before making such statements. Scott has done much more than the cosmetics mentioned.

Todd

[Kaveman]

Ok, we're stuck here. Like I said, ALTERNATIVE ENGINES.

Oh gentlemen of the Wise Council, allow me to plead this case.

I present to you a link


Here are some photos for your review:

You can see the ancestry and thus the line of logic.