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XTS-210 25hp rotary engine; 1/5th size/weight of diesel piston engines

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Re: XTS-210 25hp rotary engine; 1/5th size/weight of diesel piston engines

#11

Post by IronWolve »

Zak wrote: post #5
IronWolve wrote: post #3

My twitter ads have been flooded by this company liquid piston, it looks cool, but if the use case is to replace small engines also, I need to see a drop in crate replacement for a honda or cheap chinese motor for a generator/atv/scooter. I love tote-goats, they use the old 5hp engines, if I could get a diesel version that I could use (for farm use and cheap diesel), count me in if it works.

Do the ads want you to buy engines, or invest in the company? Last time[0] I saw this on HN, it appeared very targeted toward military UAV applications rather than anything most consumers would have a use for. [0] https://news.ycombinator.com/item?id=35455286

Just got one NOW, yes invest. They are still paying to promote their product.

630.7K views, https://twitter.com/LiquidPiston/status/1625932968865693718

Re: XTS-210 25hp rotary engine; 1/5th size/weight of diesel piston engines

#13

Post by Phlarp »

wongarsu wrote: post #9
Animats wrote: post #6

Earlier quoted context omitted.

Yes. Makes you wonder how real this is. And how long it lasts. The military might want it for drones. Even if it's only good for an hour, that's a good survival time in modern combat.

They mention "the XTS-210 engine addresses the fuel efficiency, lubrication, and fuel type limitations of the traditional Wankel rotary engine", but while they quote great fuel compatibility, don't waste more words on efficiency and lubrication. So just based on the marketing fluff I expect those two points to still be worse than traditional diesel engines, just good enough for military applications. And given the ot…

Adding in the 2 stroke design and wide ranging fuel compatibility to the above military centric specs, I have to imagine the emissions profile is truly stunning.

Re: XTS-210 25hp rotary engine; 1/5th size/weight of diesel piston engines

#15

Post by ChuckMcM »

This is a pretty cool engine. 25hp is about 18.75 kW so a really good fit for a 15kW generator (sometimes marketed as "whole house" generators) its high RPM (typical of rotary engines) makes it a good match foundation for a turboprop engine. A pair of these driving ducted fan turboprop engines would give you an excellent long duration drone platform with good payload capacity.

My guess is the Army might be considering them as APUs (Auxiliary power units) on armored vehicles as this would give them long duration "sitting" capability without running the main power plant (but using the same fuel). Similarly bus style RVs could use them to run their in-vehicle electric gear (not a lot of bus RVs are designed for the "dry camping" or boon docking market but it would definitely work well for that.

The next thing they have to figure out I'm guessing is how to make them inexpensively (the Army won't care so much but I don't think the company would survive on just Army contracts).

Re: XTS-210 25hp rotary engine; 1/5th size/weight of diesel piston engines

#16

Post by Zak »

IronWolve wrote: post #11
Zak wrote: post #5

Earlier quoted context omitted.

Do the ads want you to buy engines, or invest in the company? Last time[0] I saw this on HN, it appeared very targeted toward military UAV applications rather than anything most consumers would have a use for. [0] https://news.ycombinator.com/item?id=35455286

Just got one NOW, yes invest. They are still paying to promote their product. 630.7K views, https://twitter.com/LiquidPiston/status/1625932968865693718

"The first major innovation to the internal combustion engine in over 100 years" claimed there suggests they're not familiar with the Wankel rotary engine upon which their design is based; the modern eccentric shaft version first ran in 1958.

Re: XTS-210 25hp rotary engine; 1/5th size/weight of diesel piston engines

#17

Post by inferiorhuman »

wongarsu wrote: post #9
Animats wrote: post #6

Earlier quoted context omitted.

Yes. Makes you wonder how real this is. And how long it lasts. The military might want it for drones. Even if it's only good for an hour, that's a good survival time in modern combat.

They mention "the XTS-210 engine addresses the fuel efficiency, lubrication, and fuel type limitations of the traditional Wankel rotary engine", but while they quote great fuel compatibility, don't waste more words on efficiency and lubrication. So just based on the marketing fluff I expect those two points to still be worse than traditional diesel engines, just good enough for military applications. And given the ot…

Dollars to donuts the rotary will be easier to manufacture and maintain than the diesel. It's got fewer parts and the parts themselves are way simpler. Lubrication's easy if you don't care about efficiency or emissions, which the military doesn't.

Re: XTS-210 25hp rotary engine; 1/5th size/weight of diesel piston engines

#18

Post by joecool1029 »

I wish they had video of the two-stroke design in operation. There's a bunch of their 4-stroke engines being demonstrated by this youtube channel: https://www.youtube.com/watch?v=TDFAjCOM3iQ This one is interesting as it shows difference between their 4-stroke design and a standard wankel rotary in operation, wondering if the two-stoke variation looks like a combination between the two?

Re: XTS-210 25hp rotary engine; 1/5th size/weight of diesel piston engines

#19

Post by toss1 »

This is more hype than performance.

When I worked on a hybrid-power multirotor drone about eight years ago, I was checking out Wankel engines for their power-weight ratio, and also came across this Liquid Piston crew. They were supposedly ready to ship Real Soon Now. But worse, their power-weight just didn't compare to Wankel options available then.

Liquid Piston still do not compare on their headline power-weight ratios. They make a lot of claims about 25 HP (18.6kW) and light weight, but don't actually mention the weight, which is down in their spec sheet - 21.2kg dry [0], which is about 0.877kW/kg.

By comparison, just a quick search of small Wankels turns up these:

-- AIE model 225CS outputting 40 bhp / 30kW weighing 10kg = 3.0 kW/kg[1]

-- AIE model 80S outputting 15 bhp / 11.2kW weighing 5kg = 2.24 kW/kg [2]

-- Sorrel Hiperlight Wankel outputting 75 hp / 56 kW weighing 52kg (fully wet with all electric start, reduction drive, and exhaust system, etc. = 1.07 kW/kg [3]

-- Crighton CR700W motorcycle engine puts out 220 hp / 164 kW weighing 43kg = 3.8 kW/kg. [4]

-- Small Nitto NR20-EP puts out 2.24kW / ~3hp weighing 1.466 kg = 1.53 kW/kg. [5]

In short, this is a lot of marketing hype for low pefrofrmance, and they've been working on it since 2003 according to their website.

The sole advantage this engine might have is running on a broader range of fuels including JP-8, but I've seen Wankels setup for a wide fuel range also. If I had a funded task to develop a high power-weight engine, I'd start with the Wankel design, not this one. It is already WAAAY ahead, and there's still a lot of performance left on the table.

[0] https://uploads-ssl.webflow.com/5f6086e9bbbabd41a20f2984/642...

[1] https://www.aieuk.com/225cs-40bhp-wankel-rotary-engine/

[2] https://www.aieuk.com/80s-15bhp-wankel-rotary-engine/

[3] http://www.ultralightnews.com/sunfun99/hiperlight.html

[4] https://newatlas.com/motorcycles/dual-rotary-crighton-cr700w...

[5] https://barnardmicrosystems.com/UAV/engines/wankel.html

Re: XTS-210 25hp rotary engine; 1/5th size/weight of diesel piston engines

#20

Post by skykooler »

ChuckMcM wrote: post #15

This is a pretty cool engine. 25hp is about 18.75 kW so a really good fit for a 15kW generator (sometimes marketed as "whole house" generators) its high RPM (typical of rotary engines) makes it a good match foundation for a turboprop engine. A pair of these driving ducted fan turboprop engines would give you an excellent long duration drone platform with good payload capacity. My guess is the Army might be considerin…

This would definitely be interesting in an RV, it's way more compact than engines in similarly powerful generators in a vehicle where space is at a premium - and the ability to run off the same diesel fuel as the main engine is a huge plus.
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