Crazy idea of the week - Scale Magister

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Jay Kempf

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Since it's virtually certain that nobody here is actually going to build a little jet based off of this engine, how about we assume, for the moment, that this engine actually performs as-advertised. That is not an endorsement of the company or the product but, short of someone buying one of these engines and doing their own independent test, this sidebar argument is pointless and isn't going to be resolved here.

The thread was started by the OP with regards to designing an airplane around such an engine. That's a fine exercise, and if any of you don't believe the engine's performance, consider this a thought exercise as if that engine actually exists. Or simply don't participate. If you want to argue the merits or demerits of this engine as a topic, my first recommendation would be to do it via PM. Or start a separate thread specifically about this engine. This thread is meant to be about an airframe designed to suit this engine, on the assumption that it does what the manufacturer claims. Derailing it into an argument about the engine itself is off-topic, and further posts in that direction will be moderated.
How much range would most fit this config? That gives a weight of fuel to work with. The rest can fall in behind that.
 

Topaz

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How much range would most fit this config? That gives a weight of fuel to work with. The rest can fall in behind that.
Not a lot, I'm guessing. But as the OP said, this would be a toy. A fixed engine sizing would be interesting, with the range set as the fallout. Use the MTOW of the SubSonex as a starting point, and plug in the numbers for this engine.
 

Himat

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How much range would most fit this config? That gives a weight of fuel to work with. The rest can fall in behind that.

Pretty short I guess. If the stated fuel consumption is at full power one engine consumes 52,2kg fuel in 30 minutes. If the aircraft was bee a twin thats a little more than 100kg fuel in half a hour. Then, 80kg pilot, 2x10kg engines and 100kg fuel and we are at 200kg. In some other thread it was stated that the all up wheigt shouldbe less than 3 times the thrust.

784/9,81=79,9kg times two engines times three and the all up weight arrives at 479kg. Where 200kg already is the pilot, engines and fuel. Leaves 279kg for the airframe.
 

Jay Kempf

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Pretty short I guess. If the stated fuel consumption is at full power one engine consumes 52,2kg fuel in 30 minutes. If the aircraft was bee a twin thats a little more than 100kg fuel in half a hour. Then, 80kg pilot, 2x10kg engines and 100kg fuel and we are at 200kg. In some other thread it was stated that the all up wheigt shouldbe less than 3 times the thrust.

784/9,81=79,9kg times two engines times three and the all up weight arrives at 479kg. Where 200kg already is the pilot, engines and fuel. Leaves 279kg for the airframe.
I don't know about you guys but .5hr duration isn't of much interest to me. Let's get more sophisticated about range. Let's use the VLJ sort of mission requirement which is say 5 minutes of taxi at idle, then 10-15 minutes of best climb, then X minutes of best cruise and .5 hrs of descent at say 25% power and another 5-10 minutes in the pattern, all that with some reserve. What sort of range could be gotten out of say 50 gallons? There is no way to build an airplane with a small wing for this sort of scenario so the Magister is a good target. Sort of half glider, half jet in config. What is really nice about these little engines is that they mount easy and don't require any real fancy ducting if on pylons near the CL. The way VLJ's get range is to go up high quickly and then pull the levers back to sip fuel. Of course they are all high bypass fans.

If the range could be more like 500-750 miles at a reasonable speed then this could be a viable single seat traveller. I am guessing not though. I am guessing it is a flying fuel tank that is going to burn $8/gallon Jet A like a dragster.
 

Topaz

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I don't know about you guys but .5hr duration isn't of much interest to me. Let's get more sophisticated about range. Let's use the VLJ sort of mission requirement which is say 5 minutes of taxi at idle, then 10-15 minutes of best climb, then X minutes of best cruise and .5 hrs of descent at say 25% power and another 5-10 minutes in the pattern, all that with some reserve.
Depending on your cruise altitude, half-an-hour descent seems high to me. Twenty minutes ought to do it, generously, unless you're planning on being up in the flight levels.

What sort of range could be gotten out of say 50 gallons? ...
Time to crack Raymer and run a sizing. Between the engine numbers you have and the description you've already made, you should have (or be able to extrapolate) enough information to do a first-order sizing. Run it either fixed-MTOW (guesstimate that) and let range fall out, or run it conventionally and see what the aircraft MTOW comes out to be. Check what climb rate is possible with that MTOW, power, and wing, and iterate until you get something that climbs well enough on that engine-airframe combo. Whatever range you get there is what you get.

This won't be "accurate", but at least it'll give you a ballpark answer.
 

Aircar

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How about that Cri Cri carrying a Mitsubishi "Shogun" under it ? -Oriol's top right picture (titled "Flying Shogun" ) --now THAT is a flying car !:gig: seems the problem has been solved -dang.
 

cluttonfred

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OK, first off, when I first opened this thread I thought we were talking about a Miles M.14 Magister and I couldn't figure out why in the world anyone would want to put a jet engine in a replica of one!

Magister-1.jpg

That said, my mistake did get me thinking that if looking for inspiration for a "fun with small jets" homebuilt project, you could do a lot worse than the Miles M.77 Sparrowjet, a successful modification of a piston-engine racer using two 330 lbs thrust (each) Turbomeca Palas engines.

Miles_m-77.jpg

I have often daydreamed about a single- or two-seat sport plane powered by a single turbofan in the central fuselage with bifurcated inlets and outlets like the beautiful Hawker Sea Hawk.

hawker-seahawk-cutaway.jpg

And, of course, if dreaming about small jets you will find lots more inspiration in the personal jets history section of Luc Van Bavel Design. Just think what we could do today with a concept along the lines of Yves Gardan's SIPA S.200 if only there were an economical small turbofan on the market.

sipa200minijet.jpg

If anyone finds such an engine, say 200-400 lbs thrust, reasonable weight and TBO and the cost of a new small piston engine, say $20,000 or less, let me know!
 
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