4 ms·

Clickbait. It's a 4 pound engine that makes 3 horsepower. Impressive, but the article says the 40 pound engine makes 6.5 horsepower. Also, one costs $50 and the

Clickbait. It's a 4 pound engine that makes 3 horsepower. Impressive, but the article says the 40 pound engine makes 6.5 horsepower. Also, one costs $50 and the other probably $50,000. And no information given about the 4 pounder.

noir_lord 10y ago
> LiquidPiston says that their X-mini is still in a testing phase, and they hope to get the weight down to 3 pounds and the power up to 5 hp. (The 40-pound piston engine produces about 6.5 hp.) That's an unkind reading, for many applications a 5hp 3lb engine would replace a 6.5hp 40lb engine (not least because you put two 3lb engines at 5hp in for a total of 10hp at 6lbs..). In any case it's a fascinating engine and the application for things like drones are pretty obvious.
- dharma1 10y ago
  I wonder how it compares to fuel cells on drones, in terms of weight of the engine and energy density of the fuel
  - oofabz 10y ago
    The problem with fuel cells is power output. They are very efficient and reliable but they generate much less power than a mechanical engine of the same weight. Power/weight ratio is very important for aircraft engines.
    - dharma1 10y ago
      You are right, power/weight ratio is important. I've seen news pop up in the last 12 months of fuel cell powered drones with several hours flight time (compared to under an hour with li-ion batteries) so I'm assuming they can push out enough power for a multirotor for decent lift without weighing too much. Fixed wings should definitely see good gains, as it requires less power to fly than multirotors. I haven't followed it closely but 5-10x flight times vs li-ion sounds realistic considering the energy density of hydrogen. http://www.hes.sg/ http://www.hes.sg/
- whamlastxmas 10y ago
  Having a conditional "they hope to" makes that information worthless. I hope be to be a billionaire for sitting on my ass, it doesn't mean it's likely or that I'm even working towards it.
kbenson 10y ago
> but the article says the 40 pound engine makes 6.5 horsepower. So? Every production car engine today weighs more than 40 pounds and makes more than 6.5 horsepower. That doesn't obviate the need to lighter engines, even if they are less powerful. > Also, one costs $50 and the other probably $50,000. Doubtful (and where are you getting $50k from?). You can see most of what goes into the engine in the video. Their advances seem to be mostly process and shape changes, not due to some space age material. It may cost $1000 in its current incarnation, but that's what you get when you manually machine all the parts instead of have them mass produced.
- whamlastxmas 10y ago
  1. My point was that it wasn't a replacement. It's not even capable of getting half the power. Hence my claim that the title was clickbait, it's patently false. That's like saying I invented a replacement motor for the Bugatti Veyron at half the cost, oh by the way it makes 400 horsepower instead of 1000. 2. Again it's my demonstration of clickbait. A 40 pound engine that makes 6.5 horsepower will never be replaced by an engine featured in the article. At least, not in the next several decades. An engine that weighs 40 pounds and makes 6.5 horsepower is called a lawnmower engine. It's cheap to make and maintain and people use it because it's affordable. People aren't going to replace their $50 lawn mower engine with one that's $1000.
  - kbenson 10y ago
    I'm not sure why you think replacing an engine has to entail having the exact same performance as before. > That's like saying I invented a replacement motor for the Bugatti Veyron at half the cost, oh by the way it makes 400 horsepower instead of 1000. You can. What's wrong with that. Maybe there's something else about the engine that makes it noteworthy, such as it being electric? In this case, it's a way to showcase specific aspects of the engine, it's size and weight. > A 40 pound engine that makes 6.5 horsepower will never be replaced by an engine featured in the article. Might it be replaced by two 4 pound engines with a total of 6 horsepower for 8 pounds? Or maybe three for 9 horsepower for 12 pounds? Perhaps the efficiency can scale and they can do a single motor for ~9 horsepower and ~12 pounds? > It's cheap to make and maintain and people use it because it's affordable. It's cheap because it's mass produced. You can't compare how useful this engine is to existing engines without considering the cost when built at the expected scale. > People aren't going to replace their $50 lawn mower engine with one that's $1000. I'll just repeat myself with inflection: "It may cost $1000 in its current incarnation, but that's what you get when you manually machine all the parts instead of have them mass produced."

noir_lord 10y ago

> LiquidPiston says that their X-mini is still in a testing phase, and they hope to get the weight down to 3 pounds and the power up to 5 hp. (The 40-pound piston engine produces about 6.5 hp.) That's an unkind reading, for many applications a 5hp 3lb engine would replace a 6.5hp 40lb engine (not least because you put two 3lb engines at 5hp in for a total of 10hp at 6lbs..). In any case it's a fascinating engine and the application for things like drones are pretty obvious.

dharma1 10y ago
I wonder how it compares to fuel cells on drones, in terms of weight of the engine and energy density of the fuel
- oofabz 10y ago
  The problem with fuel cells is power output. They are very efficient and reliable but they generate much less power than a mechanical engine of the same weight. Power/weight ratio is very important for aircraft engines.
  - dharma1 10y ago
    You are right, power/weight ratio is important. I've seen news pop up in the last 12 months of fuel cell powered drones with several hours flight time (compared to under an hour with li-ion batteries) so I'm assuming they can push out enough power for a multirotor for decent lift without weighing too much. Fixed wings should definitely see good gains, as it requires less power to fly than multirotors. I haven't followed it closely but 5-10x flight times vs li-ion sounds realistic considering the energy density of hydrogen. http://www.hes.sg/ http://www.hes.sg/
whamlastxmas 10y ago
Having a conditional "they hope to" makes that information worthless. I hope be to be a billionaire for sitting on my ass, it doesn't mean it's likely or that I'm even working towards it.

kbenson 10y ago

> but the article says the 40 pound engine makes 6.5 horsepower. So? Every production car engine today weighs more than 40 pounds and makes more than 6.5 horsepower. That doesn't obviate the need to lighter engines, even if they are less powerful. > Also, one costs $50 and the other probably $50,000. Doubtful (and where are you getting $50k from?). You can see most of what goes into the engine in the video. Their advances seem to be mostly process and shape changes, not due to some space age material. It may cost $1000 in its current incarnation, but that's what you get when you manually machine all the parts instead of have them mass produced.

whamlastxmas 10y ago
1. My point was that it wasn't a replacement. It's not even capable of getting half the power. Hence my claim that the title was clickbait, it's patently false. That's like saying I invented a replacement motor for the Bugatti Veyron at half the cost, oh by the way it makes 400 horsepower instead of 1000. 2. Again it's my demonstration of clickbait. A 40 pound engine that makes 6.5 horsepower will never be replaced by an engine featured in the article. At least, not in the next several decades. An engine that weighs 40 pounds and makes 6.5 horsepower is called a lawnmower engine. It's cheap to make and maintain and people use it because it's affordable. People aren't going to replace their $50 lawn mower engine with one that's $1000.
- kbenson 10y ago
  I'm not sure why you think replacing an engine has to entail having the exact same performance as before. > That's like saying I invented a replacement motor for the Bugatti Veyron at half the cost, oh by the way it makes 400 horsepower instead of 1000. You can. What's wrong with that. Maybe there's something else about the engine that makes it noteworthy, such as it being electric? In this case, it's a way to showcase specific aspects of the engine, it's size and weight. > A 40 pound engine that makes 6.5 horsepower will never be replaced by an engine featured in the article. Might it be replaced by two 4 pound engines with a total of 6 horsepower for 8 pounds? Or maybe three for 9 horsepower for 12 pounds? Perhaps the efficiency can scale and they can do a single motor for ~9 horsepower and ~12 pounds? > It's cheap to make and maintain and people use it because it's affordable. It's cheap because it's mass produced. You can't compare how useful this engine is to existing engines without considering the cost when built at the expected scale. > People aren't going to replace their $50 lawn mower engine with one that's $1000. I'll just repeat myself with inflection: "It may cost $1000 in its current incarnation, but that's what you get when you manually machine all the parts instead of have them mass produced."