Skyflash, Jet Powered Glider

[team_skyflash]

Hi everybody,

this is Fritz from germany. Our team is currently building the first prototype of a jet powered, manned microplane. We call it "Skyflash". You can find daily updates, pictures and more at our website and on facebook:
http://www.skyflash.org/Slideshow/Ho...e-english.html
http://www.facebook.com/pages/Skyfla...02971813056201
We started our project five years ago. Through some prototypes and models we came to the first real Skyflash airplane that is currently under construction. Our goal is total freedom of flight without large structures or anything around you. It should feel just like the wings are a part of your body. But, unlike a lot of skydivers, wingsuits or stuff like that, we will have a landing gear, a regular powerplant and easy, self-stable, controlability.
The plane will be powered by two 80hp jet turbines consuming 440gr/min of Diesel fuel. Wingspan is 3,40m and max. speed is planned at 200mph. Weight is typically around 250lbs including the pilot and everything else. The whole plane is controlled only by the movements of the pilot, just like a hangglider.

Our first roll and stability tests have been captured and uploaded to youtube =)


I´d be glad to post our status and more information here if you like our project!
We hope to manage our first flight in the first or second quarter 2013. I´ll be very happy to see our post between all those great projects that I´ve already seen there!
In germany, or europe generally, we have no institution like the EAA and so I´m very glad that there are so many impassioned aviators here in the US.

Best regards from germany


Fritz

[rwanttaja]

Interesting project. The thrust line seems above the center of mass; wonder if you'll have to tilt the engine a bit to compensate for the pitch-down moment of power application.

With no aerodynamic controls and the pilot strapped to the structure, how is roll controlled? I understand you're using arm drag for yaw and leg motion for pitch. If a wing drops, how does the pilot pick it up?

What is your intended flight test plan? Are you going to glide test it first?

For some reason or another, this reminded me of a long-expired US Patent from back in the '20s:



Ron Wanttaja

[team_skyflash]

Thanks first for posting this interesting patent! You´re definitly right - looks quite a bit like our design. But I think our dream isn´t the newest at all - We´re just crazy enough to realize it...

Regarding your points -
The nose down moment of the engines is not too strong but calculated. It will have to be compensated by the pilot at lower speeds and depends very much on the flown speed, the wing will create a nose-up moment at higher speeds. The nose down shall also be some kind of a stall protection - Whenever something gets critical you can put the throttle up and the plane will recover. Due to your feet beeing in the engines jet-stream, you can apply a lot of force (for example at take-off) to annihilate this moment even without floating air around you.
Also, in addition to what you see at most CAD printings, the pilot has a V-tail mounted at his feet. This has quite a strong lever-arm to the force applied by the engines moment.

The pilots reaction on a dropping wing will be pretty much like the reaction of a hang glider pilot would be - bringing your center of gravity to opposite direction. If that doesn´t has enough effect, he can, different to a hang-glider, also put his arm in front of the leading edge of the upper wing - thus destroying the lift there, and move his legs creating a rudder effect with his V-tail. We already tried that out with the preliminary gliders :-)

Tests will start directly with the engines mounted due to the very important influence they have on stability and applied forces on the airframe. We will post a lot of details regarding the tests and controls later on our website.

I hope my english is understandable, don´t mind to ask!

Best regards

[rwanttaja]

Thanks first for posting this interesting patent! You´re definitly right - looks quite a bit like our design. But I think our dream isn´t the newest at all - We´re just crazy enough to realize it...

Regarding your points -
The nose down moment of the engines is not too strong but calculated. It will have to be compensated by the pilot at lower speeds and depends very much on the flown speed, the wing will create a nose-up moment at higher speeds. The nose down shall also be some kind of a stall protection - Whenever something gets critical you can put the throttle up and the plane will recover. Due to your feet beeing in the engines jet-stream, you can apply a lot of force (for example at take-off) to annihilate this moment even without floating air around you.
Also, in addition to what you see at most CAD printings, the pilot has a V-tail mounted at his feet. This has quite a strong lever-arm to the force applied by the engines moment.

The pilots reaction on a dropping wing will be pretty much like the reaction of a hang glider pilot would be - bringing your center of gravity to opposite direction. If that doesn´t has enough effect, he can, different to a hang-glider, also put his arm in front of the leading edge of the upper wing - thus destroying the lift there, and move his legs creating a rudder effect with his V-tail. We already tried that out with the preliminary gliders :-)

Tests will start directly with the engines mounted due to the very important influence they have on stability and applied forces on the airframe. We will post a lot of details regarding the tests and controls later on our website.

I hope my english is understandable, don´t mind to ask!

Your English is excellent, especially considering that you're discussing technical details.

You've looked into the nose-down moment with power, so I'm feeling better in that regard.

I'm still just a touch uncertain regarding roll control. CG shift is a classic method of control (invented by a countryman of yours over 100 years ago, I believe :-). But the CAD drawing on your web page makes it look like the pilot was going to be strapped solidly to the wing...if he is, how does he shift his weight? Or is he hanging from a short harness that lets him shift? I can see disrupting the airflow to control roll, but is the pilot going to be able to make the necessary arm motions at 200 MPH?

I can see you needing the engines in place during testing. It just seems to me that a glide test with the engines off might allow the pilot to get accustomed to the handling prior to being under power, and without fuel and hot metal being present. Though I expect power-off and power-on pitch handling to be quite a bit different....

Ron Wanttaja

[team_skyflash]

Thanks you! If I may choose a totally wrong vocabulary just let me know an I´ll explain further what I want to say =)

I understand what point you´re making regarding the roll control. The difference to other aircraft is that we don´t need a very wide CG-shift due to our reduced wing-area and our aspect ratio of just 3,4.
We have an physiological advisor in our team who very much influenced the development of the pilots mounting. Totally fixed without any chance to move is just the hip of the pilot. This means that, for no reason ever, even in gusty conditions, the pilots whole Body will move anywhere - for safety reasons. The hip, which represents the CG of the human body, is his fixed point. Whenever the pilot want´s to stabilize he can strain all his muscles - thus bringing the plane back in neutral position. He is always in control of the airframe. Unlike, for example, the pilot of a hang-glider who has no direct physical control of the wing.
When our pilot wants to move the plane he can swing his arms, his chest and, very important, his legs to the side he wants the CG to move to. Supported by the aerodynamic effect of this body movements, the plane will react very fast.

So what am I trying to say; Basically our plane uses very much a combined form of CG-shift and aerodynamic controls. At low speeds, when the aerodynamic forces are lower, you mostly control the plane by moving your CG. This gives you a very good control and feeling of what´s happening, especially when taking off or landing. At higher speeds you switch to a mostly aerodynamical control and align your body to the airframe.
The forces applied by the pilots movements have been tested with the 2/3 model when plane and pilot were hanging on a string in 1m height.

Regarding your question to the force needed to move your body at 200mph. We in germany have the advantages of our Autobahn ;-) We just tried the attacking forces up to 160/170mph out...
Your ability to move is of course very much affected by the immense airspeed, but you can still make the movements needed to control the airplane. At those higher speeds you also need a lot less body-motion to create the force you need to turn the airplane.
Its important to know that 200mph is representing the upper limit of speeds to be flown. Typical flight speeds will be around 70 - 120mph.

I hope this could answer some of your questions =)

[rwanttaja]

Excellent, thanks! Looking forward to watching your progress.

Ron Wanttaja