Rocket on Rotor: 1954 auxiliary steam power

[John Eacott]

Fascinating discussion of RoR, including Myrtle the Mysterious Manifold and the trials and tribulations getting the concept to a practical working result on the HRS-2 helicopter.

https://youtu.be/RRrYdIqrnWY

[Ascend Charlie]

Funny how they say these tip rockets barely added any noise to the engine. Musta been a really noisy engine.

[John Eacott]

Even better that the result out of the tips is just water vapour; is it really a rocket?

[skadi]

is it really a rocket?

Any material which leaves a nozzle produces thrust, so yes it's a rocket.

https://en.wikipedia.org/wiki/Steam_rocket

skadi

[Al M]

People still talked about this when I arrived at SA in 1963. The story told most often was when the peroxide leaked out at a time when no one was there. Peroxide is a potent oxidizer and the aircraft was constructed with a lot of magnesium. The aircraft was pretty much consumed. There was a lot of rusty steel left.

[ShyTorque]

From the figures quoted it seemed that the extra weight of the fully laden system was just about compensated for by the extra performance.

Reminds me of the time we used to under sling air portable fuel containers (APFCs, commonly known as “bollocks”, because that’s what they resembled) in Belize, to set up a forward refuelling point. By the time we’d got them there, we had to refuel from them to get home...

[diginagain]

From the figures quoted it seemed that the extra weight of the fully laden system was just about compensated for by the extra performance...
Not unlike the surplus Whirlwind legs bolted onto a Lynx to create the Mk9.

[Droop Snoot]

Peroxide is a potent oxidizer and the aircraft was constructed with a lot of magnesium. The aircraft was pretty much consumed.


As if Mg needs the least bit of encouragement to combine with his friend O and return from whence they came!

[John Eacott]

From the figures quoted it seemed that the extra weight of the fully laden system was just about compensated for by the extra performance.

Reminds me of the time we used to under sling air portable fuel containers (APFCs, commonly known as “bollocks”, because that’s what they resembled) in Belize, to set up a forward refuelling point. By the time we’d got them there, we had to refuel from them to get home...

ST, if you watched the complete video it showed a significant performance increase with the ROR installed. At about 16min into the video the ROR machine goes out against a standard HRS-2 and lifts an extra 800lb with the ROR fitted and tanked; the T/O appears noticeably quicker than the standard machine, too.

[triskele]

Er, what happens with those long slim blades, for the rotorhead pulls them round and the tips follow a teeny bit later; with the jets surely now the tips are pulling the rotorhead?

[ShyTorque]

ST, if you watched the complete video it showed a significant performance increase with the ROR installed. At about 16min into the video the ROR machine goes out against a standard HRS-2 and lifts an extra 800lb with the ROR fitted and tanked; the T/O appears noticeably quicker than the standard machine, too.

The figures quoted were that a fully installed and fuelled rig weighed almost 400lbs. Extra payload 200lbs?

[John Eacott]

The figures quoted were that a fully installed and fuelled rig weighed almost 400lbs. Extra payload 200lbs?

If you go to the point I mentioned they have two HRS-2s as a direct comparison with identical loading internally, then add 800lb underslung to the RoR machine. I can’t see how you’re coming to your conclusion?

If anything it would show that the modified machine is lifting 800lbs more plus the weight of the ROR equipment, but that’s stretching assumptions with the info available.

[ShyTorque]

If you go to the point I mentioned they have two HRS-2s as a direct comparison with identical loading internally, then add 800lb underslung to the RoR machine. I can’t see how you’re coming to your conclusion?

If anything it would show that the modified machine is lifting 800lbs more plus the weight of the ROR equipment, but that’s stretching assumptions with the info available.

I have difficulty believing that a Whirlwind would be flown half a tonne overweight. I never flew the piston engined version but I did fly the HAR10; My notes tell me the MAUM of that version was 8,000lb; an increase of 1,000 lb would be miraculous. If this WAS the case, why was this equipment not universally fitted to all similar helicopters?

[John Eacott]

Gee whiz, we’re going round in circles here. I don’t recall saying the aircraft was operated over MAUW and the video specifically refers to limiting weights to aircraft specs. The comparison is of flying with standard two pilots and six troops, then adding the equivalent of another four troops to the ROR machine in the fly off.

The ROR system weighed in at 67lbs dry, with a tank capacity of 300lbs. One can only assume (and we’re both making assumptions here) that the fuel load was factored in to the take off weight, as would be the AVGAS, arriving at identical aircraft weights before adding the ballast equivalent to six troops.

[ShyTorque]

Sorry John, as you say, it’s all supposition so chill out a little. As far as I can see, the system was never adopted by any operator. There would have been good reasons for that.

[Arnie Madsen]

I know of at least 2 peroxide - steam powered helicopters built and flown as test models. Very simple ... pretty much only one moving part (rotor) and once turning , the centrifugal force draws the H202 liquid to the tips where it passes thru a silver screen which acts as a catalyst to turn it into steam.
No fuselage torque but this one has a small low speed t/r for yaw control
Runs quiet as you can see
Pilot hand pumps initial fuel then uses a valve/throttle to control flow.
https://www.youtube.com/watch?v=CGcRgEuCocQ

[Droop Snoot]

Er, what happens with those long slim blades, for the rotorhead pulls them round and the tips follow a teeny bit later; with the jets surely now the tips are pulling the rotorhead?


As you state, the rotor thrust is proportional to the steady blade lag angle. To produce more thrust, the collective pitch angle is increased, which demands more torque at the rotorhead, up to the limits of the engine.

To allow more rotor thrust at a constant rotor RPM, the tip rockets allow additional pitch angle by compensating for the associated increased aero drag. The steady lag angle can be held at the previous value, hence the engine is providing the same power to the rotor as the baseline aircraft.

Essentially, the engine and rocket share the increased power requirement, with the engine operating within previously established limits. However, the differences in blade weight distribution (due to the plumbing), rotor dynamics (including transient loads due to rocket "ignition" and shutdown), static and fatigue loads, etc., must be considered before the system could be certified.

[Ascend Charlie]

Hovering this thing on a humid day, which would have created tip vortex cloud trails, would make visibility a bit tricky with the extra vapour?