A 4 engine jet as homebuilt ?

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topspeed100

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I introduced in the wood structure area an idea of a 4 engine jet ( 4 x model engines ). To top the existing Cri Cri and BD-5 records for the smallest jet.

Would that have difficulties in regulation side ? Engines are to be overhauled at just 25 hours of use ?

Also pilots eligible to fly a small beast would be small portion of race pilots and army / navy pilots..perhaps few commercial pilots ! Would this make it an less desired in air space in general ?

I assume ( by Cri Cri jet and BD-5J and BD-10 ) that this could go 450-500 km/h..perhaps even 700 in a dive. Engines would only cost 14,3 K€..thus it could be quite easily achieved by a homebuilder.

Would this project run into NSA and FBI investigations if tried to be sold to anyone ? I did realise that there is a certain unwanted element of it when in wrong hands ? Drug smugglers could get away with it very fast etc. It could also for its diminutive size be almost undetected in a radar ?
 

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Turner

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Not that I have much experience in that area, but I belive smuggling wouldn't be a issue with such a small craft. That is, the payload is insignificantly small that it would not be worth it. In Sweden we have a 250 kts TAS limit below 10k and if you show up with something that routinely break that limit you'll get problems with the authorities if nothing else.

Other than that I like the design. Wood will probably not hold up for the high speeds though, carbon fiber and possibly kevlar (on a high budget) would make more sense. I'm not sure what the running cost is on those small jets but I'd imagine component lifespan and reliability would be issues to look at. The wheel size may be of concern considering the landing speed and I'd consider higher aspect ratio to get the best low speed handling. Perhaps a design more like the F18 with strakes and slightly swept or straight wings?

By the way, since there is no engine in the fuselage why not put those little burners on top and in between the fins? It would reduce noise and minimize risk of fob ingestion while keeping engines easily accessible for maintenance.
 

Dana

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I don't know about Finland, but in the US it would be no problem; you can build and fly nearly anything. As Turner pointed out it'd be too small to carry any significant contraband or weapons so nobody would care about that. Might take a skilled pilot to safely fly it, but legally any Private pilot can fly any experimental aircraft solo regardless of whether he has specific ratings for the aircraft.

-Dana

When Marriage is Outlawed, only Outlaws will have Inlaws.
 

Turner

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The more I think of this the more I like it. It could be relatively easily tested in 1/2 or 2/3 scale RC using the same engine as the full scale but two or possibly three instead of four. How feasible it would be to use RC turbines on a full scale machine I do not know, never flown RC jet. I suspect maintenance is expensive on those engines as the life span can not be expected to be anywhere near as good as a "real" turbine. Nevertheless I fired up SolidWorks to start sketching on it using your rough dimensions and proportions as a reference. I hope you don't mind. :)

Edit: Go to www.minijets.org for some of the neat jets used in gliders.
 
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topspeed100

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The more I think of this the more I like it. It could be relatively easily tested in 1/2 or 2/3 scale RC using the same engine as the full scale but two or possibly three instead of four. How feasible it would be to use RC turbines on a full scale machine I do not know, never flown RC jet. I suspect maintenance is expensive on those engines as the life span can not be expected to be anywhere near as good as a "real" turbine. Nevertheless I fired up SolidWorks to start sketching on it using your rough dimensions and proportions as a reference. I hope you don't mind. :)

Edit: Go to Price of Passion, minijets website for some of the neat jets used in gliders.
As long as you are not stealing my concept I don't mind. You seemed to have ideas of your own about placing the engines above etc..


Thanks for the link and the comments.

Enclosed my v-8 powered mach 3 mover ! Did you have this in mind ( F-18 + straight wings ) ?
 

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flyvulcan

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Hi Topspeed,

Your concept is not new... My project is about half built already, hopefully to be finished later this year. If my two 150lbf engines are not mature enough in their development, then I was considering using 4 of the same manufacturers smaller engines (90lbf each) which are already in production as an interim measure. Carrying the fuel to feed these gas guzzlers is the biggest issue (and concern) because you need a lot for any sort of useful range/endurance.

Cheers
 

antero

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but legally any Private pilot can fly any experimental aircraft solo regardless of whether he has specific ratings for the aircraft.

-Dana
Really? a private pilot could fly a multi engine, complex, high performance airplane without any of those ratings? I tried searching the FARs for something along those lines and failed, where can one find that in writing?
 

topspeed100

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Hi Topspeed,

Your concept is not new... My project is about half built already, hopefully to be finished later this year. If my two 150lbf engines are not mature enough in their development, then I was considering using 4 of the same manufacturers smaller engines (90lbf each) which are already in production as an interim measure. Carrying the fuel to feed these gas guzzlers is the biggest issue (and concern) because you need a lot for any sort of useful range/endurance.

Cheers
Well I did not mean my idea is 4 engines, but the concept as a whole.

I have 200 liters capacity and that will give nearly 80 minutes at full thrust flying time. It is also very volatile so test flight might have only 40 liters for few minutes of flying.
 

Dana

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Really? a private pilot could fly a multi engine, complex, high performance airplane without any of those ratings? I tried searching the FARs for something along those lines and failed, where can one find that in writing?
If he's solo and it's experimental, yes. See 61.35(l)(2)(iii)(B) and this thread, down near the bottom.

-Dana

Politics: Poli (many) - tics (blood sucking parasites)
 

Workhorse

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Well I did not mean my idea is 4 engines, but the concept as a whole.

I have 200 liters capacity and that will give nearly 80 minutes at full thrust flying time. It is also very volatile so test flight might have only 40 liters for few minutes of flying.
I suggest to try moving a 200 liters full of liquid barrel by hand. You could get an idea of what structure is needed to handle this volume and weight while flying at high speeds.

PS. Wacht your feet while doing it!.
 

highspeed

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200 liters is around 52 gallons. A gallon of Jet A weighs 6.7 pounds, so that's right around 350 pounds of go-juice.
 

Kristoffon

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Really? a private pilot could fly a multi engine, complex, high performance airplane without any of those ratings? I tried searching the FARs for something along those lines and failed, where can one find that in writing?
The same way he can get a driver's license for motorbikes and hop on a Hayabusa going 250 mph the next day. Doesn't mean he should.
 

topspeed100

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200 liters is around 52 gallons. A gallon of Jet A weighs 6.7 pounds, so that's right around 350 pounds of go-juice.

That makes pretty big pond fire if somethings goes wrong. Gosh I just burned my hair just yesterday when liting up a barbeque grill in a windy day outside...and I only used 1/4 cup of flammable liquid.
 

CALL911

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...pilots eligible to fly a small beast would be small portion of race pilots and army / navy pilots..
The US Army's pilots fly helicopters (okay to be exact, their air power does have about less than 1% planes). I think you would be better off with an Air Force pilot, or if you couldn't find any, maybe a Navy pilot ;)
 

CALL911

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Ok Air Force pilot then...how about Marine Corps pilot ?
Aviators in the USMC are trained by the Navy and are considered Naval Aviators. In fact, USMC F-18 squadrons frequently deploy aboard carriers as part of the air wing.
highspeed is correct. Look I do give props to any military pilot. But I have seen the training up close and personal of all the branch's different pilots (since I went through it myself), and I can tell you that to go through Navy/Marine training is a walk and the park compared to the brutal gauntlet that the Air Force goes through. Not saying that makes all the difference, but just from my own personal experience, minus landing on a carrier at night, I give the props to the Air Force pilots.
 
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