Greatest speed per engine HP

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Matthew Rogers

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Beat this - 5.83mph/hp. Equivalent for a Cessna 150 would be 583 mph!
 
Just wait till the glider pilots start chiming in!

But that albatross was a good one. Think about the fuel economy if you just put a 1 hp motor on it and sit back and relax. I guess it would actually be perfect for an electric motor.
 
Since velocity/HP is not linear relationship , the slower you go the higher it will be, everything else being equal.
 
Matthew Rogers said:
Just wait till the glider pilots start chiming in!

But that albatross was a good one. Think about the fuel economy if you just put a 1 hp motor on it and sit back and relax. I guess it would actually be perfect for an electric motor.
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Then balloon pilots (they don’t need help getting airborne).
 
asicer said:
How about the Gossamer Albatross, max speed 18mph on 2.5hp?
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2.5 hp looked high to me. Looking at Wiki, it appears that an elite cyclist can generate 400 watts or .6 hp for an hour or so.

Pretty incredible to get anything to fly on that, regardless of speed.
 
MooneyDriver78 said:
Since velocity/HP is not linear relationship , the slower you go the higher it will be, everything else being equal.
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That's why I think a rubber band balsa wood plane might beat most everything else.
 
Slow always wins since power required per speed is cube law.

To double the speed you need eight times the power.

Or a hill.
 
Silvaire said:
Technically balloon pilots have zero airspeed so they're out.
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Balloons are also very inefficient. We'd burn around 22 GPH of propane in our balloon. In one flight I went 3 miles like that, so over 7 gallons per mile.
 
Ted said:
Balloons are also very inefficient. We'd burn around 22 GPH of propane in our balloon. In one flight I went 3 miles like that, so over 7 gallons per mile.
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Should've launched in a tornado. Would've really upped your efficiency numbers.
 
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Ted said:
Balloons are also very inefficient. We'd burn around 22 GPH of propane in our balloon. In one flight I went 3 miles like that, so over 7 gallons per mile.
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I’m assuming helium ballooning is expensive?
 
MooneyDriver78 said:
I’m assuming helium ballooning is expensive?
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I wouldn't call it expensive. A breakdown of what we've found:

Balloon itself, you can buy a used one in the range of $8-20k depending on what you want pretty easily. Ours was more or less right in the middle of that range and is in quite nice shape.

Propane is around $2.50/gallon (give or take) so that's your fuel cost. You fly for generally a max of an hour at a time.

Insurance, as a student pilot, is <$1k/yr, and annual is the same.

If you pay a crew, then there's what you pay the crew. But most of the time if you have friends, you can find people willing to crew for you in exchange for balloon rides as they rotate through.

Really the hard part is getting everything lined up. Learning to fly has the challenges of getting your PPL (need weather, aircraft, and instructor to line up) with extras (weather is even more fickle and you need ground crew).

Edit: The above is all for hot air. You said helium (duh). I don't know how helium ballooning compares, but you don't have the same consumption.
 
kyleb said:
2.5 hp looked high to me. Looking at Wiki, it appears that an elite cyclist can generate 400 watts or .6 hp for an hour or so.

Pretty incredible to get anything to fly on that, regardless of speed.
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Right, I was using peak HP because I think most engines use that on their spec sheets. I believe you are correct regarding max continuous power at high cruise.
 
If we're sticking to man carrying airplanes, the Davis DA-11 cruises 125mph on 18HP for 6.9mph/hp.
 
Spring Ford said:
Slow always wins since power required per speed is cube law.

To double the speed you need eight times the power.

Or a hill.
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Well, as the DA-11 posted above shows, that is not always the case. It goes 25% faster than my C150 with only 18% of the horsepower. 1 seat vs 2, but still.

How much further can speed be pushed at low horsepower? This might be one of the first ways towards really useful electric airplanes.
 
Maple Flag, Cold Lake, Canada in 1983 on a 0C day in an F-15 doing 800 knots in full afterburner drinking 150,000 lbs/hr of JP4 to chase down a couple of Canadian F104s at 500 ft AGL. Don't know the mph/hp number, but does it matter when you're having that much fun?
 
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