Interesting Comparison

[red750]

I spent Friday at the Formula One Grand Prix practice sessions. My son couldn't use his ticket because he had to work, so he lent it to me. The announcer was commenting on modifications to the cars to reduce their weight to as close as possible to the minimum permissible weight - 642 kg. I thought it interesting that it' s just below the maximum weight of recreational aircraft.

 

.

 

 

[Guest Michael Coates]

Problem is the HP difference...... IMAGINE a 600 hp engine in a sport plane.

 

 

[mnewbery]

http://en.wikipedia.org/wiki/Scaled_Composites_Pond_Racer

 

After takeoff for the final event on Sunday, the left engine threw a rod out the side of the block and created a tunnel of fire 4 feet (1.2 m) in diameter and about 15 feet (4.6 m) long.

No thank you.

 

 

[metalman]

Problem is the HP difference...... IMAGINE a 600 hp engine in a sport plane.

Mmmmmm, imagine that,,,,drooling

 

 

[mnewbery]

This is the closest thing I can find

 

http://en.wikipedia.org/wiki/XCOR_EZ-Rocket

 

If you had a single prop it would be something like a PT6A-11 or -28 with a honking big four blade prop that has its centre at about eye height.

 

Mathematically, a 1 Kg per Kw ratio produces 2G of acceleration. If the prop was 50% efficient you'd still have enough power to hover. Far more performance than even the best stunt plane. Acceleration from 100 Kts to 200 Kts in well less than 6 seconds. By the time you take into account the drag equations 50% is probably still a bit high. But you get the idea.

 

A static thrust equivalent for 600Kg would be around 2,500 lbs.

 

The sonex jet thrust is 240 lbs. A Robinson R22 hovers on 180Hp. Different Reynolds number due to the slower blade speeds, see, so it's more efficient.

 

In summary a 600hp, 600kg plane with a single propellor would have an insanely high nose on the ground, have trans sonic blade tips more often than not, a necessarily huge rudder area and generally try to kill you by wanting to flip over on its back speeding up _and_ slowing down. So you'd need two engines or a contra-rotating arrangement. More mass up the pointy end so the wings would need to be almost on top of the gear box.

 

Rubbish bin ugly with a wing over the engine - probably a biplane - and a really freaking long empennage with up to three huge rudders. You'd want a spare rudder just in case, at 250 Kts, one tore off.

 

The jet would just send you broke by the time you got to the holding point and start grass fires.

 

If that's your dream, go for it. I'll be the one standing a safe distance away with a video camera and a fire extinguisher. I've often noticed that physics will still kill you when you ignore it.

 

 

[siznaudin]

Just this once, bugger the prop ... here's my Walter Mitty "Chuck Yeager" disguise.

 

http://www.bd-micro.com/NewsReleaseFLS_Microjet.pdf

 

Oh, and having coped with just a little of Sunday's F1 event - I can't wait for the real racing season to start.

 

MotoGP and Superbikes, in case you hadn't guessed.

 

[ATTACH=full]1715[/ATTACH][ATTACH=full]1716[/ATTACH]

 

[ATTACH]18377[/ATTACH]