Jet Engines

[prkaye]

Don't get me wrong, this is not something I'm even remotely considering. But I'm curious, does anyone know if anybody has ever attempted to put a jet engine into an RV? Is this even possible?

[pierre smith]

There is a jet-powered, self launching sailplane and the guy does incredible aerobatic shows with it. It has two small, retractable mini-jets manufactured in the USA. You could sling one under the RV I reckon. This is their site
http://www.usamt.com/
Regards,

[xl1200r]

This guy can fly with them...wonder the plane weighs.

The most powerful one makes 45 lbs of thrust and weighs only 5.3 lbs - but at $4000 each I'd bet you'd need to spend a lot of cash to get an RV into the air and flying like it was designed to.

I sure would like to see 6 or 8 of those things hanging on the wings of an RV though - would pretty cool if you ask me.

[TSwezey]

Those are model airplane engines.

[captainron]

Do you need a multi-engine rating for that?

[Ironflight]

Originally Posted by captainron

Do you need a multi-engine rating for that?

One.....Two....yup, looks like a multi to me!!!

[JeffD]

From below I think a 315lb thrust engine might work.


**warning below is rough calculations*

I have thought about this. Honda's jet runs off of two HF118 that produce 1,700lbs of thrust each. Max takeoff weight is 9,200lbs. So thats (1,700*2)/9,200= 0.369 power to weight ratio. Max speed is 420kts. Only need about half that for an RV so chop the power/weight ratio by half Brings it down to 0.1845 .

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

RV max takeoff weight is 1700lbs *0.185 = 315lbs of thrust to get close to the current performance. granted these are pretty gross figures and some sketchy interpolation.

Fuel. 2300lbs(384 gallons) of fuel for a range of 1,100NM
Again using the same interpolation 384*0.369*0.5= 70.8gallons
1100/70.8 = 15.5miles/gallon

Yeah 7-8 of those 45lb engines would do the job, kinda like a B-52 (Although the B-52 is going to only use 4 engines pretty soon)

Wish I could at least try it

Edit: Anyone know of jet engine suppliers besides GE, Rolls Royce etc? Smaller engines but not so small as the ones above.

[xl1200r]

There are other things to consider with a jet...

An RV is designed to have a propeller pulling th eplane from the front, so you need to have the weight of the engines up there, and I would think you'd also need to thrust from engines being derived from the front of the plane as well. I think you would have a use a setup more like the one I pictured above rather than just haning them off the wings, unless you planned on doing some rather substantial modifications to the airframe to move the wings rearward in order to the CG correct.

Also, I don't know the Rolls-Royce makes much in the name of smaller jet engines. I think your big names are going to be GE, Pratt & Whitney and Williams. Looks like the Honda jet is using engines built by GE as well.

*EDIT* - Looks liks Rolls Royce does make small jets as well...

[gmcjetpilot]

Jet Hang glider!

http://www.alexisparkinn.com/photoga...hanglider_.mov

And here is an aerobatic routine of the plane pictured above, Cri-Cri (Cricket) french home built (but with piston engines).

http://www.alexisparkinn.com/photoga...intheworld.wmv

I am pretty jaded watching aerobatics, but that's an impressive roll rate. I would not fly the thing straight -N- level much less roll it on takeoff. Here is the web site for these "world's smallest twin engine planes": http://flight.cz/cricri/english/index.php

Note the pre-shut down run0up to clear the plugs at the end of the video, I love it!!, ha ha, oh my, who says the French don't have a sense of humor. Here is another Cricket stunt: http://flight.cz/cricri/vids/cri5.qt

JETS ANYONE?

May be their is a future for small jet engine GA planes. The very light Bizz jets are coming, like the Eclipse and Honda jet. What engines do we have now for a little personal two seat jet?

The Williams Intl engine (http://www.williams-int.com/high/pro...gines/fj33.htm) is the lowest thrust commercial jet engine they make for passenger planes, at 1000 lbs. The fj33 is still too much thrust for a light plane and cost a fortune no doubt. Need something in the 400-600 lb range, that cost no more than a Lycoming and gets great fuel burn. (right)

RC model jet engines top out at 50 lbs of thrust, burning 11 gal/hr, at about $6,000 each, you would need a couple of them; not practical, except for a novelty like Mr Jet Hang Glider or the Cricket dude.

Than I came across something interesting Amtusa. They are making a jet engines for the goverment. It's current thrust is spec'ed at 150-200 lbs, $32,500. Burns 23-31 gal/hr at max thrust (est). Could you get airborne with 200 lbs thrust. May be in a Cricket, not a RV size plane. It's even a little low on thrust for BD-5J, which uses about 300 lbs thrust with a microturbo TRS18: http://www.gasturbine.pwp.blueyonder.co.uk/TRS18.htm.

Are real, affordable, safe, economical personal jet's practical? Probably not. Single engine jets for the GA pilot masses is a dream, at least for now. Reading about the poor (terrifying) history of BD-5J's, I've no desire to fly one.

Here is another high powered jet engine (relative to RC models): http://www.microjeteng.com/hf150.html (150 lbs thrust at 39 gal/hr). They also have a 130 hp turboprop. http://www.microjeteng.com/prop_pics2.html The turbo prop looks like a mini P&W PT6. He uses his gas section to drive a turbine coupled to the prop dirve, meaning its no a direct drive turbine, aka PT6. Interesting.

These cruise missile engines are not man rated. Meaning I would not fly with one. You will not likely ever get over the fuel burn and poor takeoff performance with a small jet.

Want to get scared? Here are links on the BD-5J (jet). There are almost too many accidents to count. Almost every one that has flown, seems to have crashed at some point. The first link starts with a description of a toy model BD-5J, but at to bottom is an impressive list of accidents and links of real BD-5J's. The second (Wikipedia) list three notable BD-5J crashes, two of which tragically both just happened recently in June of this year.

http://www.xs4all.nl/~robdebie/models/bd5.htm (list at bottom of page)
http://en.wikipedia.org/wiki/Bede_BD-5

Little single engine micro jets are not for the GA public, but that's my opinion. From the list of accidents of jet powered BD-5J's (well all BD-5's) it seems like a dangerous way to fly. It remains to be seen what happens when the VLJ's (very light jets) start being flown single pilot by private pilots. Low time inexperienced pilots in jets is a recipe for an accident. Hope that does not happen.


Although the RV is not suited for a jet engine,
here's my jet powered RV project :

[mgomez]

At 375 mph, 1 lb of thrust = 1 HP. Note that it's thrust horsepower, not shaft horsepower...the losses in the prop matter. So to calculate how much thrust it takes to propel your airplane at a particular speed, do this:

T = HP x 375 / mph

A 200 HP RV that goes 200 mph TAS @ 75% power and has an 80% efficient prop therefore requires 225 lbs of thrust for cruise. However, if you do the math during a full-throttle climb at 90 mph sea level:

T = (0.8)(200) x 375/90 = 667 lbs of thrust

That's a thrust-to-weight ratio of about 1/3, which is not unlike a bizjet...which is why RVs climb like bizjets. If you sized the engine for cruise, the airplane would climb like an underpowered brick.

Then there's the fuel consumption...model airplane jets have an SFC of about 2 lbs/lb-hr. At 225 lbs of cruise thrust, you'd be burning 450 lbs/hr. A "real" small turbojet has an SFC of about 1 lbs/lb-hr, which means you'd be cruising at 225 lbs/hr (or about 3x what a Lycoming burns).

Note that you won't be going any faster, at least not if you take the Vne limitation seriously.