Dragonfly jet-powered helicopter runs on H2O2, shuns traditional tail rotors (video)
Your average whirleybird is driven by a big motor in the middle, spinning the blades one way and, as per Newton, rotating the body of the craft the other. A tail rotor counteracts the force, but a more efficient solution is to have the rotors power themselves, which is exactly how the Dragonfly DF1 works. It has tiny, hydrogen-peroxide jets on the blade tips, spinning them up without pushing the body of the helo in the other way -- though a small tail rotor is still needed to turn the craft. It's much like the tech that propelled James Bond toward his waiting DB5 in Thunderball, but unlike that jetpack this copter can fly for up to 50 minutes. It's the product of Swisscopter Americas and, while they've been playing with the DF1 for many moons now (demonstrated in a video below), the company is also working on the DF2 shown above, a rather more civilized version that seats two. The DF1 is certified for flight in the US, looks to be available for sale and, while no price is listed, they are said to be much more friendly to the environment than traditional helicopters. That'll surely add to the premium.
I'll take 2
@tmkates : choo-choo-copter!
@One Love
http://www.youtube.com/user/fly1now#p/u/4/3HOj6szdGGU
Their YouTube-channel, this is the DF2... purring like a cat. Hope they will get permitted in germany ;)
@One Love ROFLCOPTER goes swishswishswishswish!
Hooray for antiseptics!
Just be sure to wear white when around it.
Because you WILL be wearing white AFTER being around it.
I understand white hair and eyebrows is in, too.
looks cool but noisy
@Waad
It's a helicopter. They make noise. At least this one does not involve gasoline.
Just watched the video.
The guy standing within head-chopping distance of a test flight is beyond DUHmb.
@Freakin Ijit That was exactly my first thought. I wouldn't be anywhere within 100' of that thing.
@Freakin Ijit actually it would be safer to stand directly beneath it then to attempt to run away since if the blades did come apart, they would fly outwards.
@Freakin Ijit I'm sure this wasn't the first test flight.
It is nice to see the old Sikirsky idea of rotor tip jets making a comeback. If this works well it could herald a crop of such devices.
I am not sure that I like the idea of H2O2 (HTP) since I am sure that the tank will be inboard and the liquid will need to be pushed through a moving joint. HPT tends to blow up when brought into contact with metals other than stainless steel and a few others that I cannot remember.
@rederikus
The company web site includes a description of their hydrogen peroxide fuel product:
"Hydrogen peroxide (H2O2) was first successfully used in the thirties of the last century as rocket fuel. Mixtures over 70% (H2O2) are highly explosive and are considered for Military Use only and therefore excluded from civil use. A mixture of 50% (H2O2) and additives was developed, which is very difficult to ignite but can be easily stored and transported."
Assuming that it's as simple and clean as it looks, I think these things would be the cat's meow. What happens when these things are all over the place and we're seeding the atmosphere with H2O2?
@JB47394 I wonder what the actual concentration % of H2O2 they're using. 50% is the highest you can get commercially, but I don't think it's available to the general public. Plus 50% H2O2 will burn the shit out of you. You need protective gear just to handle it.
@rederikus
Usually silver is used as a catalyst, right?
@chispito
I think they spray the hydrogen across an aluminum screen to combust it.
@rederikus
Old tech ideas just redone and tweaked.
http://www.youtube.com/watch?v=YFF6zzpU3o8
that is a seriously cool new helicopter even if the start of the video does make it look like a mashup between anime and steampunk
From the wikipedia article on H2O2
Explosive vapors. Above roughly 70% concentrations, hydrogen peroxide can give off vapor that can detonate above 70 °C (158 °F) at normal atmospheric pressure.
o_O
I wonder if you could do little electric propellers on the end as an alternative? Maybe something a hobbiest could do on the cheap for fun?
@geolemon Physics goes against the idea here. For the same reason that piston powered aircraft get very inefficient approaching the speed of sound you couldn't put props on the end because the blade (on the prop) would have to spin so fast, to make the rotor roate quickly enough, that the tips of the props would break the speed of sound. This risks equipment failure as it increases strain on not only the prop but also the gearing for the prop (it has to push through the shockwave when it breaks the sound barrier plus the drag of it (increases with the square of the speed) means that such an idea is unfeasible. Plus piston engines are a lot more complex, heavy and biiger than 'jets' are.
Sorry, but this looks like it will be an expensive game :(
@gingerninja AH! That should be square of the INCREASE in speed. I.e. 80 mph has 4 times as much drag as 40mph. (2 times the speed equals 4 times the darg, 3 times the speed equals 9 times the drag etc.)
and you can use the hydrogen-peroxide to disinfect the cut when the rotor cuts you. :)
@One Love One cut only if you're lucky. And you better bring somebody along to help you reach for your bottom half... :P
That's not a helicopter, but a Headchopper...
@monkeyman87 : stealth mode!
An other Site says, the flight time is about 100 minutes with an optional extra tank..... awesome! I'd like to buy it, but I'm in Europe... DF2 is also really awesome, imagine flying with this little baby above a small city ;)
"The Wrong Brothers" LOL!!
I kid, I kid ;^)...
The broomstick connected directly to the swashplate with no damping.
The ground guide hanging around long after the rotors have spun up.
Cars driving by during the test flight... I guess having him take off 50-100 meters away from everyone would be too much to ask.
The portable container with people and fuel hanging out 30-40 feet away.
OMG... I think watching that made me age. Former Army maint test pilot. I'm dizzy after watching that. Jesus.
Anyway... I think it needs wheels instead of skids.
Here's a much better link than the "source" link above:
http://www.tecaeromex.com/ingles/RH-i.htm
TAM the company that makes the H2O2 engines also makes rocket packs:
http://www.tecaeromex.com/ingles/RH-i.htm
@baltwade here's the rocket pack link:
http://www.tecaeromex.com/ingles/indexi.html
I'm curious if anyone has ever designed a jet-powered helicopter that uses the jet exhausted, ported through duct work to the tail, rather than a tail rotor.
It seems if a VTOL aircraft can use redirected exhaust to vector the aircraft, a helicopter should be able to use some of the jet exhaust to counter the copter's rotation.
@Spiny Norman NoTaR
@Spiny Norman Here ya go... http://en.wikipedia.org/wiki/NOTAR
@Spiny Norman Yep, check out the MD Explorer:
http://en.wikipedia.org/wiki/MD_Helicopters_MD_Explorer
-tim
p.s. Did you ever find Dinsdale?
@TimStevens
Thanks, guys. It appears that this approach uses a separate internal fan, rather than the exhaust from the primary engine. Perhaps it's difficult to route the exhaust into the tail structure.
No, I haven't caught up with Dinsdale, yet. But, when I catch him I'm going to nail his head to a coffee table.
@Spiny Norman Well it uses the jet exhaust, it looks like, to spin that fan. I is a bit of a hybrid i guess
@Spiny Norman: Why would you want to use the turbine exhaust directly? That would give you less control over the tail than the NOTAR setup. After all, we are talking about turbine exhaust, not thrust from a jet or turbofan.
Okay, just a point of clarification. This is NOT a HELICOPTER. It is, in fact, a Gyrocopter. Gyrocopters have been around almost as long as helicopters, but have generally seen limited commercial or military success. One of the big challenges is already apparent in the information above -- flight time. Advantages like no counter-rotation, reduced fuel usage, etc. don't really overcome the problem of flight time. It should also be noted that to create forward motion, another motor is needed to push the vehicle in a direction. This is usually accomplished by use of some sort of [turbo] fan or possibly even a small jet engine, so while there are still fuel savings and overall less complexity, it is not quite as simple as it sounds.
@RichStar I have to disagree. This is a helicopter as evidenced by the fact that it can hover. A gyrocopter uses a propeller for forward motion this forces airflow over the rotor system and turns it into a lifting body. Without thrust an autogyro must enter autorotation.
The rotors on an autogyro ARE NOT driven by an engine but instead are rotated only by the airflow through them.
@RichStar How is this a gyrocopter? Gyro's need forward momentum to achieve lift. Some of them can prespin the rotors for a shorter takeoff, but they can't takeoff vertically.
@RichStar
I believe "gyrocopter" is a trade name. Gyroplane is correct. Gyroplanes come in all sizes, including ultralight versions requiring no license to operate. I know- I built one in my living room many moons ago, and promptly wadded it up on my first takeoff run, despite having taken lessons. I finally achieved my dream of flight when I discovered powered paragliding, but that's another story :)
@RichStar This is definitely not a gyrocopter. The rotor is directly driven to produce lift and thrust.
I stand corrected. Quoted from Wikipedia "Tip jets
Main article: Tip jet
Another single main rotor configuration without a tail rotor is the tip jet rotor, where the main rotor is not driven by the mast, but from nozzles on the rotor blade tips; which are either pressurized from a fuselage-mounted gas turbine or have their own turbojet, ramjet or rocket thrusters. Although this method is simple and eliminates torque, the prototypes that have been built are less fuel efficient than conventional helicopters and produced more noise. The Percival P.74 was underpowered and was not able to achieve flight, while the Hiller YH-32 Hornet had good lifting capability but performed poorly otherwise. Other aircraft relied on supplemental thrust so that the tipjets could be shut down and the rotor could autorotate after the fashion of an autogyro. The experimental Fairey Jet Gyrodyne and 40-seat Fairey Rotodyne passenger prototype were evaluated to have flown very well using this method. Perhaps the most unusual design of this type was the Rotary Rocket Roton ATV, which was originally envisioned to take off utilizing a rocket-tipped rotor. No tip jet rotorcraft have ever entered into production."
I should point out however, that in the past it has been attempted to use tip jets as part of a "gyro" type vehicle, to allow for vertical take off and landings on a craft that otherwise behaves like a gyrocopter. The military explored such a device long ago, with the idea of creating a cost effective way of having highly mobile air infantry/cavalry. They also looked at using it as a sort of "Jeep" for the skies. As pointed out, the method is very noisy, and not generally very fuel efficient, which ended up killing the development of these types of craft. I suspect a similar result will occur with this one.
Great thought! In my mind there would still be a slight force on the body, but maybe I was just sleepy during my physics classes? I would love it if someone could explain it to me.
@blinddance That's why it still has a small tail rotor.
@barry99705 that's what I thought. Thank you for clarifying :)
@barry99705 Not really, it has a tail rotor to be able to control the direction of the body.
Whatever rotational forces that is transferred to the body would only be what is transferred by the friction in the bearings.
One would think that a simple rudder of sorts mounted in the downward air stream from the rotor would be enough to provide directional control for the body.
@LEDfoot I agree with barry99705. The article states that the tail rotor is solely for providing direction control but I imagine that some of the power is used to keep the body from turning, due to the friction between the rotor and the body. A roder would not work for that. Furthermore, a roder requires the whole body to move forward (or backward) in order to turn it, a tail rotor however makes rotation on the spot possible.
In either case, it seems that the force of the rotor can be a lot less when using this technique, as opposed to a rotating engine in the body.