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Wednesday
Mar172010

Swisscopter Dragonfly DF1: Tip-Jet Helo That Might Actually Work!

 

Dragonfly DF1 tip-jet helicopter from Swisscopter

 During the first minute of this video you're very likely gonna think: watch out, crazy people alert!  But that will soon transform to something more like: hmm, this thing is very interesting and really seems like a totally stable flying platform with serious potential.  What strikes me is that this may be the first time we've seen a truly viable solution to the idea of having a tip-powered rotor.  As the video of the Hiller HJ-1 I posted a while back shows, the tip-powered rotor idea has been around for a long time.  It just seems like there's always been hurdles too high to clear that have keep the concept from having a genuine application.

 The Swisscopter company is hoping to prove that they have a great solution in the Dragonfly DF1.  Swisscopter is operating out of Tucson, Arizona, but there's definitely some connections to Switzerland, and a trip around their website at Swisscopter.us definitely suggests it's not just a U.S. venture.  In fact, a little digging lead me to find that the design was known a few years back as the Intora Firebird.  This brief history on the Firebird helps to shed some light on the fact that this concept has been in the works, and around the globe for a lot of years now!  Hopefully they're getting close to a real success now, and I'm sure that watching this project progress is gonna be fun.

 The most unique feature of the DF1 is the H2O2 (hydrogen peroxide) rocket motors mounted at the rotor tips.  The hydrogen peroxide you might have in your medicine cabinet is only a 3% solution, but when it's at much higher levels, like 70%, it makes a dandy rocket fuel.  If I understand the process correctly, introducing the high percentage solution to a catalyst like silver or manganese dioxide causes the rapid decomposing of the hydrogen peroxide into high temperature steam and oxygen.  That explains all the steamy puffs seen in the video.  And hey, it's pretty hard to argue with an exhaust that's just water and oxygen!  The rocket motors also seem to be extremely simple, low maintenance, quiet and reliable.  

 A couple other quick things to note about the DF1.  As a tip-powered rotor, it doesn't need a tail rotor to counteract torque, however, the DF1 does have a small tail rotor that it uses to be able to control yaw.  Gyrocopters also don't need a tail rotor since their overhead rotor is free rotating, but they have a propulsion engine with prop blast pointed at a rudder to control yaw.  Without that prop blast, the DF1 needs some other tool for yaw control.  The DF1 also appears to be very quiet which seems like it could be a real plus in gaining acceptance.  Questions remain about how safe the high concentrations of hydrogen peroxide are and how easy the fuel would be to obtain.   I also wonder about the steam produced by the rockets.  As can be seen in the slightly fuzzy video below, massive amounts of the steam can be produced, which makes for some awesome flow visualization, but also makes it a little foggy for the pilot when landing!  I'm assuming that this issue has been dealt with and that the video above is representative of the state-of-the-art (maybe they did something special to the rockets to make that much steam?)

 Lastly, here are some DF1 specs: cruise 40 mph; max speed 115 mph; empty weight 235 pounds; gross weight 800 pounds; max rate of climb 2,300 fpm; duration at cruise 50 min to 1 hour 40 minutes depending on tank size. 

 I sure hope we get to see the Dragonfly DF1 at Oshkosh!

 

 

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Reader Comments (4)

Very cool gizmo! Throw some lighting onto the steam at night and I reckon Project Blue Book are back in business!

March 20, 2010 | Unregistered CommenterTurb Coriolis

Pretty crazy... in a good way. Fun to follow progress!

July 28, 2010 | Unregistered CommenterMichael Boze

Very impressive I first saw a video on the Fairey Rotadyne this used tip jets or rotor jets built in the fiftys in UK rotadyne unfortunately struggled to get any orders?? And they scrapped it?? Why it didn't go to a museum I don't know. It was funded by government but typical UK mentality as UK have had many advanced projects scrapped?
Rotadyne didn't have a problem with hydrogen peroxide for fuel as used a fuel air mixture so why use hydrogen peroxide?
Haven't researched it enough to know what fuel they used but be worth a look.
I first saw the dragonfly 3 years ago and think it's simplicity is the future of gyrocopter as an add on for vertical take off and landing.
This will come next I'm sure. I think there is a company that has already developed this.
I wonder if the dragonfly will get a UK license to fly approval. That would open the flood gates for more civilians to take to the air as must be a third the price of gyrocopter a and micro lights.
Nick Carroll

March 13, 2015 | Unregistered CommenterNick Carroll

To add to my comment and correct the odd spelling mistake Fairey Rotodyne used a compressor which ran off its prop engines the fuel was kerosene.
But a compressor pump could run off the tip-jet rotor once it got going with a hand or foot pump to act as a pre-primer once ignition of tip-jets was achieved it would create it's own pressure. If if the tip-jets were used as an addition to to existing gyrocopters for take off and land only it would make for a very impressive and economical piece of kit and could become the future for helicopters being more reliable and doing away with the engine and gearbox or power take off transfer case thus reducing weight and making it more reliable.
I think it will happen in future but things sometimes move slowly? There is a saying in Sales called KISS "keep it simple stupid"

March 14, 2015 | Unregistered CommenterNick Carroll

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