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## Main Question or Discussion Point

So by now, everybody's probably seen the news and videos of Yves Rossy, the Swiss pilot, jetting around over the Alps with wings strapped to his back, and 4 mini-turbojet engines attached to those wings. The entire apparatus is said to weigh 120 lbs.

Each of his 4 engines is a JetCat P200, with specs as follows:

Thrust at full power 50 Lbs / 220N

Weight incl starter 4.8 Lbs / 2.2Kg

Diameter 5.1 inches / 130mm

RPM Range 33,000 - 110,000

Exhaust temp 670C

Fuel consumption 25.37 oz min at full power

Fuel Jet Al, 1-k kerosene

Lubrication 5% oil mixed in fuel

Maintenance interval 50 hours

But apparently his flight only lasted 5 - 10 minutes, due to fuel constraints.

I was wondering how this might be improved upon.

I was reading that turbofan engines typically offer superior fuel efficiency over turbojets, as well as quieter operation. Also, Yves had to wear thermal protection because of the heat from the jet exhaust, and hopefully turbofan exhaust is less hot. Another thing is that a turbofan could perhaps reverse thrust by flipping the blade angle, allowing aerobraking for landing without a chute.

But how do they fare on thrust-to-weight ratio?

I hunted around the next for the smallest turbofan engines I could find. One site I found was this one:

http://cpl.usc.edu/eschuste/

The other I found was this one:

http://www.globalsecurity.org/military/systems/aircraft/systems/f107.htm

So the smaller engine out of those two turbofans seems to have a higher thrust-to-weight ratio (granted, the first one isn't a military-certified product)

Suppose we assume that a 2-engine setup is the most desirable, so that if one fails then you still have the remaining one to fly with.

Then what would be the best type of engines for our winged man?

I'm thinking that you'd want each engine to be capable of generating 100 - 120 lbs of thrust, with a max weight of 10 lbs each. Is that doable for a turbofan?

Each of his 4 engines is a JetCat P200, with specs as follows:

Thrust at full power 50 Lbs / 220N

Weight incl starter 4.8 Lbs / 2.2Kg

Diameter 5.1 inches / 130mm

RPM Range 33,000 - 110,000

Exhaust temp 670C

Fuel consumption 25.37 oz min at full power

Fuel Jet Al, 1-k kerosene

Lubrication 5% oil mixed in fuel

Maintenance interval 50 hours

But apparently his flight only lasted 5 - 10 minutes, due to fuel constraints.

I was wondering how this might be improved upon.

I was reading that turbofan engines typically offer superior fuel efficiency over turbojets, as well as quieter operation. Also, Yves had to wear thermal protection because of the heat from the jet exhaust, and hopefully turbofan exhaust is less hot. Another thing is that a turbofan could perhaps reverse thrust by flipping the blade angle, allowing aerobraking for landing without a chute.

But how do they fare on thrust-to-weight ratio?

I hunted around the next for the smallest turbofan engines I could find. One site I found was this one:

http://cpl.usc.edu/eschuste/

The other I found was this one:

http://www.globalsecurity.org/military/systems/aircraft/systems/f107.htm

So the smaller engine out of those two turbofans seems to have a higher thrust-to-weight ratio (granted, the first one isn't a military-certified product)

Suppose we assume that a 2-engine setup is the most desirable, so that if one fails then you still have the remaining one to fly with.

Then what would be the best type of engines for our winged man?

I'm thinking that you'd want each engine to be capable of generating 100 - 120 lbs of thrust, with a max weight of 10 lbs each. Is that doable for a turbofan?

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