H2O2 Tip Jet

[Woolf]

(This might have been posted already) Tip jet H2O2 prototype - very impressive!

CGcRgEuCocQ

[widgeon]

I thought tip jets did not require a TR ( or mid rotor in this case ).

[Nige321]

Does anyone know what the H2O2 concentration is?

Nige

[Arnie Madsen]

Previous models were using 93% and higher concentrations of hydrogen peroxide but the latest ones are using as low as 70% solution. The lower solution uses either an additive or something different in the silver screen catalyst. (From memory and subject to correction.)

They have designed a nice small tipjet and are also testing a 2 person model and results are good. There is a dedicated company to supply and ship fuel worldwide in an approved and regulated manner.

Fuel is expensive and so far I have not found consumption rates published other than mentions of "high consumption" so I am guessing that will be the downside.

I love tip jet rotors , they are utterly simple with only one moving part. Hopefully fuel supplies can be increased and costs brought down but it will probably require a breakthrough in that department.

[Arnie Madsen]

I thought tip jets did not require a TR ( or mid rotor in this case ).You are correct, none required. If you look close you will see the low rpm of the tail rotor. It is more of a live rudder to give yaw control. That way they eliminate having a big rudder in the downwash like some older co-axials and intermeshers used. For example look at the Kaman Husky , that is a huge appendage hanging out the back.

However I have seen the video of the 2 place peroxide powered prototype and it looks like are back to using vanes on the boom . The video was mainly head on shots and it was hard to see the boom , but yaw authority looked good. Probably was a calm day. Personally I hope they stick with a low thrust tail rotor that only needs to handle crosswinds.

[Arm out the window]

Controlling it must be weird at first if you're used to flying helicopters with a conventional arrangement of cyclic control, ie push the cyclic forward to tilt the disc and move in the same direction.
Unless I've picked it wrong from the video, it looks like the head is just a fan on a stick type setup, so to tilt the disc forward he's pulling back on the handgrip - I guess you'd get used to it, but still... I once went for a fly in a weight shift trike with a mate, and after a long time pulling back on the stick to pitch up, it was bloody strange to have to push out on the framework to keep the nose up in a turn.
Anyone had any bad experiences transitioning between control setups along these lines?

[ECFAN]

Not sure if this has been posted before.

Dragonfly jet-powered helicopter runs on H2O2, shuns traditional tail rotors (video) -- Engadget (http://www.engadget.com/2010/03/17/dragonfly-jet-powered-helicopter-runs-on-h2o2-shuns-traditional/)

check it out flying here
YouTube - H2O2 helicopter demo test tip-jet Dragonfly DF1 2009 (http://www.youtube.com/watch?v=CGcRgEuCocQ)

could rocked powered blade tips be added as a safety feature?

cheers,

Clayton

[Arnie Madsen]

Some of the earlier tests were done with what amounts to a gyrocopter rotor head. Not sure why they chose that route.

Later testing uses a typical helicopter collective + cyclic which is the way it should have been done in the first place. Even a twist grip throttle can be used to control the peroxide flow rate.