Newbie pitch

[Christ]

OK, now we're on the same page... are those HP/TQ figures right?

That seems like quite a lot for a small 1 cylinder heat driven engine.

[theunchosen]

Who said it was 1 cylinder? ^_^

Also the advantage of the Stirling cycle. . .there is no combustion. No thick steel or thick aluminum or heavy duty moving metal parts.

Moving metal parts yes but not necessarily heavy. Everything about the Stirling can be designed to be lightweight since it has to just be air-tight(opposed to being air tight and and being able to withstand a high pressure detonation).

The theoretical figures are correct. I'm not expecting to see those though. SES can get them but they spend lots of money and have automated systems that manufacture every single piece to within thousandths if not less of spec.

I'm expecting around twenty pounds and half that in horses.

The output for the Stirling is the cold side(air temp) and therefore the hot side can be used for engines further down the line. Of course you'll get less juice out of each of them but 100 lbs = 50 HP = 50% increase in FE. second most important 100 lbs in the car.

[Christ]

OK, now I'm starting to see this coming to something.

As you can tell, I'm not very familiar with the SE, other than seeing them in science classes and such.

Now, when you give me numbers, I can make the correlation... fact is, if you can get 50 HP for 100 lbs, you're doing better in overall efficiency (HP:weight) than the ICE is, in most cases.

Honda D-series engine weighs in at 270lbs (average, wet) and produces a mere 90HP (again, average.)

270:90
30:10
3:1 vs. ~2:1 for the SE.. not bad.

[theunchosen]

Their power-to-weight is not great. its actually terrible. Gas engines can get 1.0+ and diesels can come in at 1.2 and Gas turbines come in very nicely at 1.5 and higher. Scramjet engines do. . .like 50:1.
But in this situation(low power) Stirling comes in better because it does not have ti withstand detonation and the ICE does. Stirling just has to be able to withstand heat differences and high temperatures(400-800). can make them out of very thin aluminum or very thin pretty much anything heat conducive and resilient.

<edit> scramjets are just gas turbines. . .sort of. . .more like pulse engines. . .but anyway they only work at the sound barrier and faster because they ramscoop air into the manifold to achieve ridiculous intake pressure blast lots of fuel in ignite and the really high pressure acts as a barrier to keep it travelling backwards while the exhaust manifold is just a wide open cone(the pressure against the cone wall causes the acceleration). its like two big traffic cones put together with the small ends together and the fuel is ignited at the junction. vessel goes rocketing on at mach 15 or so.
</edit>

[Christ]

Actually knew that much about scramjets... not too much more.

[theunchosen]

lol. . . they are entirely the opposite of FE. They burn fuel in ratios of gallons per second opposed to gallons per mile or minute or miles per gallon.
Although you can go from New York to BaghdaD in 30 minutes. . .

[some_other_dave]

Originally Posted by Christ

...the reduction would be 30:1 (30 at the generator for every 1 at the SE) Which means that the generator would only see 1/30 of the HP that the SE is giving.

Forgive the side-tracking, but I need to point out the above statement is incorrect. When you use gear reduction (and pulley reduction is just a different type of gear reduction), you still transmit all of the power. The torque is what gets multiplied by the gear ratios, as well as the RPM. But the power stays the same.

-soD

[Christ]

Originally Posted by some_other_dave

Forgive the side-tracking, but I need to point out the above statement is incorrect. When you use gear reduction (and pulley reduction is just a different type of gear reduction), you still transmit all of the power. The torque is what gets multiplied by the gear ratios, as well as the RPM. But the power stays the same.

-soD

HP is a relative number derived from TQ...

To calculate HP: (TQxRPM)/5252=HP

That said, if torque is multiplied or divided, as the case may be, so is HP.

If an engine has 100 LBFT of torque at 1000 RPM,

100x1000 = 100000
100000/5252 = 19 (horsepower @ 1000RPM)

What you're saying is taking the speed of the driven object and deriving horsepower from it.

Example

10 LBFT @ accessory pulley, 10000 RPM (10:1 from engine)

10 x 10000 = 100000

100000/5252 = 19HP

At least from what I remember of physical science in HS, that's correct.

[theunchosen]

well, if you mean you want to gear it up(speed increase(torque reducer)) the biggest one I've ever seen is a 5:1. I don't think you can possibly get them higher than that.

I am not very familiar with the above formula's but I know the base unit for horsepower(definition) is its the ability to move 500 lbs one foot in one second.

Although. . .the above definition sounds legitimate.

I think the mishapy may have come in at the computing it for the output. The formula seems competent to derive horsepower from the engine but it seems like you just didn't multiply the output of the gear pulley by 30,000 instead of just 1,000.

i.e. you said it sees 1/30th of the power the engine produces and by that I think you mean torque. True per rpm it sees 1/30th of the torque. . .but it also sees 30x more RPMs. in using a gear assembly to change the speed/torque you effectively multiply by one because if your formulae holds you aren't changing the numerator(its torque times rpm) so if you decrease one in the pulleys you automatically increase the other. If its an ideal pulley. realistically most of it gets through but you lose some to friction and gear grinding.

[Christ]

OK, I messed up last night.

The second formula is false, the 1st and third are true...

Basically, regardless of the torque figure, when all things are equal, the same HP measurement can be taken at the drive side, or the driven side, less frictional losses.

I read up a little bit again last night on that math in one of my old science books.

soD, you were right about that. My apologies.

Edited post accordingly.