
Rocket Helicopter (2010) - jeffreyrogers
https://www.tecaeromex.com/ingles/RH-i.htm
======
milankragujevic
Wow, I used to make rocket-powered helicopters in Kerbal Space Program a few
years ago by putting a "Sepratron" on the tip of the "blade" made from
structural wing parts. How appropriate :)

See this video for more details:
[https://www.youtube.com/watch?v=1Sj_jgrokww](https://www.youtube.com/watch?v=1Sj_jgrokww)

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jeffreyrogers
The way these work is pretty interesting. Rather than combusting a fuel and an
oxidizer as in a typical rocket, these use hydrogen peroxide that is exposed
to a platinum catalyst, which causes the rapid decomposition of h202 into h20
and 02, which is then expelled through the rocket nozzle, generating thrust.
This greatly simplifies the design of the rocket engine.

~~~
mannykannot
The claim in this article is that the motors use 70% hydrogen peroxide with
alcohol (it does not say which one), without a catalyst. I have not found any
explanation of the alcohol's purpose, or whether it is oxidzed in the process.

~~~
skykooler
It's confusing, because at the top they say "This rockets don't use a
catalyst" but further down the page they say "all this thanks to our
proprietary formula of the penta metallic catalyst pack invented by Juan
Manuel Lozano Gallegos from TAM."

(Side note: I saw that name and wondered where I had seen it before; turns out
he's the guy Popular Science wrote about fifteen years ago for building his
own peroxide-powered jetpack.)

~~~
Gravityloss
Maybe they meant the catalyst is not a liquid catalyst that is consumed.

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protomyth
Sounds a bit like the Fairey Rotodyne which had the same setup using small
jets. It was very loud even for the standards of the day.

[https://www.youtube.com/watch?v=EA3AkvxwS_M](https://www.youtube.com/watch?v=EA3AkvxwS_M)

[https://en.wikipedia.org/wiki/Fairey_Rotodyne](https://en.wikipedia.org/wiki/Fairey_Rotodyne)

------
baldeagle
I'm a little skeptical about the claim of 'performance is the same at any
altitude'... while yes, the engine performance is similar at altitude, the
helo performance is not (what with the fewer air bits for the blades to move
around)

~~~
skykooler
The thing is, there's less air for the blades to move, but there's also less
drag on the blades for the same reason, so they spin faster with the same
power input. This ends up cancelling out the loss of lift, meaning that the
performance stays roughly constant with altitude until it is high enough that
the blade tips start to approach the speed of sound.

~~~
nextaccountic
What happens at the speed of sound?

~~~
Cyphase
I wondered too; here's some information I found:
[https://aviation.stackexchange.com/questions/16948/do-
helico...](https://aviation.stackexchange.com/questions/16948/do-helicopter-
rotor-tips-regularly-go-supersonic/16958#16958)

From the middle of that answer:

> In normal operations, and design aims to achieve this, the rotor tips do not
> go supersonic since when they do, there is a sudden and large decrease in
> performance with more power required, higher blade loads, vibration and
> noise.

> Think about a helicopter flying forwards. The advancing blade at its most
> perpendicular position experiences a relative airflow which is equal
> (ignoring all kinds of minor side effects) to the forward speed plus the
> speed of the blade. The retreating blade is experiencing a relative airflow
> equal to the speed of the blade minus the speed of the helicopter.

> If the blades rotate so fast that the tips are supersonic, then the main
> lift generating part of the retreating blade, the outer two thirds of the
> span, would experience such a low airspeed, for some of the span it will
> even be negative, that the blades will stall causing a catastrophic roll
> into that side. It is this phenomenon which ultimately limits the rotational
> speed of the blades and the maximum speed of the helicopter.

I also found this: [https://www.quora.com/Does-every-helicopter-main-rotor-
blade...](https://www.quora.com/Does-every-helicopter-main-rotor-blade-tip-
move-at-the-speed-of-sound/answer/Tom-Farrier)

------
bfuclusion
For any HN'ers in the bay area, if you're into this stuff you should pay a
visit to the Hiller Aviation museum. It's right by EA on the San Carlos
Airport. Hiller was a pioneer in helicopter design, and they have a ramjet
tipped 'copter on display. Here's their website:
[https://www.hiller.org/museum/aircraft-on-
display/](https://www.hiller.org/museum/aircraft-on-display/)

------
hankchinaski
doesn't this tiny rocket have very low range and bad efficiency compared to a
traditional helicopter engine? the energy density of h2o2 is close to the one
of a ion lithium battery (2.7MJ/Kg) vs the traditional gasoline+o2 (13.3
MJ/Kg) [1]. It seems like more a cool trick than something which can replace
helicopter engines?

[1]
[https://en.wikipedia.org/wiki/Energy_density_Extended_Refere...](https://en.wikipedia.org/wiki/Energy_density_Extended_Reference_Table)

~~~
basicplus2
but one is not carrying around a very heavy engine, gearbox and tail
structure.

(no heavy tail structure because there is no rotational torque from driving
the blades around against the tail rotor only gyroscopic precession when
changing direction/ tilt etc)

------
nsxwolf
How does the fuel get to the rockets without the hoses getting torn off?

~~~
tus88
It flow inside the wings (yes copters have wings).

~~~
mbrameld
Nobody actually involved with helicopters calls them wings. They're called
rotor blades.

Similarly, nobody actually involved with helicopters calls them copters.

~~~
Cyphase
Terminology aside, I think the comment was accurate.

I think it would have been better to kindly correct any terminology issues you
noticed without saying "nobody actually involved with helicopters calls them"
twice. For example:

"While `rotary wing` is an accurate term, most people in the industry would
probably call them rotor blades."

I don't think the "copter" correction was necessary, since that is in fact one
of the slang terms for a helicopter and it's clear what they were referring
to, whereas 'wing' could confuse someone into thinking of fixed wings on the
side. But if you were going to mention it, it would have been helpful to
mention what you thought would be a more appropriate term.

Just some friendly feedback! :)

~~~
mbrameld
The comment was accurate, but the parenthetical came off as arrogant and
condescending so that's how I responded.

Nothing posted here is necessary. Doesn't change the fact that nobody actually
involved with helicopters calls them copters.

Some friendly feedback right back at you! :)

~~~
Cyphase
I'll just finish with this rule from the Recurse Center User's Manual[1] that
I think applies very well to this situation:

> No well-actually's

> A well-actually happens when someone says something that's almost - but not
> entirely - correct, and you say, "well, actually…" and then give a minor
> correction. This is especially annoying when the correction has no bearing
> on the actual conversation. This doesn't mean the Recurse Center isn't about
> truth-seeking or that we don't care about being precise. Almost all well-
> actually's in our experience are about grandstanding, not truth-seeking.
> (Thanks to Miguel de Icaza for originally coining the term "well-actually.")

Direct link: [https://www.recurse.com/manual#no-well-
actuallys](https://www.recurse.com/manual#no-well-actuallys)

[1] [https://www.recurse.com/manual](https://www.recurse.com/manual)

~~~
mbrameld
Why not follow your own advice?

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AgloeDreams
Honestly makes a lot of sense.

Might be possible do do it as a ram jet too, that would get you a lot of
efficiency upsides. Typical jet engines probably wouldn't work well however
due to force but you get a fuel feed upside from the centrifugal force.

~~~
mnw21cam
Ramjets work at supersonic airflow speeds. You really don't want your
helicopter blade tips going supersonic.

~~~
chipsa
Ramjets do not require supersonic flow speeds. They require positive speed
(they don't work at a standstill), and are usually tuned for a sweet spot.
This is usually supersonic because most applications are military, where the
supersonic capability is desired. That said,they usually don't produce much
thrust until you get over M0.5.

------
pueblito
Why doesn't this helicopter need a tail rotor? I was under the impression that
it was to counteract the spinning main rotor

~~~
daniel-thompson
The difference is in where the torque is generated. In a traditional
helicopter, the engines (mounted to the main body) generate torque to spin the
main rotor. Since the body spins the rotor, by Newton's third law, the body
and the rotor spin in opposite directions. Therefore, you need a tail rotor to
counteract that.

With this design, the torque to spin the rotor is generated on the rotor
itself, so there is no torque effect on the airframe. Note that there is still
a (rotorless) tail with fins, probably to stabilize the aircraft in forward
flight.

For more on this design, see
[https://en.wikipedia.org/wiki/Tip_jet](https://en.wikipedia.org/wiki/Tip_jet)

~~~
hinkley
If you want to attach a spinning object to a stationary one you need bearings,
which means friction, which means torque. Nowhere near the torque of a normal
helicopter, but something. I take it the double fins in the back (at the end
of a long lever) can more than handle that. Or at least, as long as the
bearings don’t fail.

Gyroscopic precession, though... Is that enough tail or do you have to be
gentle changing directions in this thing?

~~~
daniel-thompson
> Or at least, as long as the bearings don’t fail.

If the bearings fail, counteracting torque is the least of your worries - you
should land immediately before the rotor shits itself and you turn into a
flaming lawn dart. From the UH-60 operator's manual:

> 9.22.10 Main Transmission Failure.

> WARNING

> If % RPM R decreases from 100% to below 96% with an increase in torque
> during steady flight with no engine malfunction, the main transmission
> planetary carrier may have failed. During a main transmission planetary
> carrier failure, it may be impossible to maintain % RPM R at 100%.

> NOTE

> Decreasing % RPM R may be accompanied by a drop in transmission oil pressure
> of 10 psi or more, and possible unusual helicopter vibrations.

> PROCEDURE

> 1\. Collective - Adjust only enough to begin a descent with power remaining
> applied to the main transmission throughout the descent and landing.

> 2\. LAND AS SOON AS POSSIBLE.

~~~
hinkley
I like to keep people guessing by alternating between ironic understatement
and hyperbole. Too much BBC perhaps.

I know in low rpm devices, especially with radial forces (wheels) a bearing or
race can start to go without destroying the whole assembly. To the point that
bicyclists can bring in a wheel that's so far gone that the labor to fix it is
twice the cost of a new wheel (I can fix this or we can get you a new _pair_
of wheels for the same price, installed). How long do you have between the
first chip and game over on a rotor?

Some how, even though "LAND AS SOON AS POSSIBLE" is in all caps, I doubt it
entirely captures the urgency. If anything involved with keeping the blades
attached fails, sounds like a case of any other plans you had are over and you
need to be on the ground RFN while it's still a choice.

------
avmich
I think Juan Lozano was making peroxide engines for early iterations of John
Carmack's Armadillo Aerospace (whose website, sadly, is now only available via
web archive...)

EDIT: yes, AA is listed as a customer.

~~~
Gravityloss
And very early on, Armadillo actually tested rotors with tip peroxide jets.
Only ground tests that I know. Moved to pure rockets quickly. High test
peroxide. Mixed monoprops with low grade peroxide and alcohol. Biprops.
Peroxide-alcohol? Lox-alcohol? Lox-methane eventually.

------
trhway
my favorite application of that tech - Roton, a helicopter to space -
[https://en.wikipedia.org/wiki/Rotary_Rocket](https://en.wikipedia.org/wiki/Rotary_Rocket)
. USSR people know it as "Pepelats" [http://copy-cats.work/aircraft02/rotary-
rocket-roton](http://copy-cats.work/aircraft02/rotary-rocket-roton) :)

~~~
app4soft
> _my favorite application of that tech - Roton_

 _Rotary Rocket_ ("Roton") is vise versa opposite design concept to _Rocket
Helicopter_.

------
nabla9
Tip jets can use compressed air. That would be more efficient.

[https://en.wikipedia.org/wiki/Tip_jet](https://en.wikipedia.org/wiki/Tip_jet)

As with all cool concepts "Zee Germans" had the idea
[https://en.wikipedia.org/wiki/Focke-
Wulf_Triebfl%C3%BCgel](https://en.wikipedia.org/wiki/Focke-
Wulf_Triebfl%C3%BCgel)

~~~
MaxBarraclough
Not _all_ the cool concepts.

The Dutch came up with the 'ornicopter':
[https://youtu.be/0Z2Rr39hiUs](https://youtu.be/0Z2Rr39hiUs)

~~~
Gravityloss
That's ingenious. It's one of those rare mechanisms that are hard to come up
with but obvious once you learn of them. I recommend everyone to watch this
video.

(The presentation spends a lot of time explaining tail rotors, which this
invention does not need. Skip to about halfway to see how it works.)

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6gvONxR4sf7o
Doesn't the pitch of a helicopter blade change as it goes around the rotation?
With a traditional rotor, the torque is always angular, but with these, the
torque will be angular plus a cyclical vertical component, since the rocket
pitch is the blade pitch. I'm wondering what the the structural and
vibrational implications are of a rocket launching the blade tip up and down
at 500 RPM.

~~~
kevin_thibedeau
There is no cyclic. The entire mast is gimbaled.

~~~
6gvONxR4sf7o
Wow, cool. I wonder if that's a big factor in why the test pilot said it was
so vibration free.

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romwell
The spiritual successor to Fairey Rotodyne[1] and other tip jet helicopters
and autogyros[2].

Hope this one takes off!

One of the reasons Rotodyne was not adopted was because it was too loud. Hope
this technology solves this shortcoming.

[1][https://en.wikipedia.org/wiki/Fairey_Rotodyne](https://en.wikipedia.org/wiki/Fairey_Rotodyne)

------
Taniwha
OK, dumb questions - the H202 is entering the combustion chamber at what
pressure? below chamber pressure,with a valve, like a pulsejet? or is there a
turbopump somewhere? and what powers it? I'm guessing centripetal force once
the rotors are spinning helps (but isn't there a potential evil feedback loop
hiding in there somewhere?)

~~~
NegativeLatency
More fuel -> faster blades -> more fuel

Eventually the blades would tear themselves off and end the the cycle.

~~~
Taniwha
yeah exactly

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vanderZwan
So does anyone know what happened after the last company that backed the
project went bancrupt?

------
iancmceachern
Looks like there are quite a few similar rotorcraft:

[https://en.m.wikipedia.org/wiki/Tip_jet](https://en.m.wikipedia.org/wiki/Tip_jet)

------
arethuza
Something that spins around at high speed using 70% hydrogen peroxide....

Don't think I'd want to be anywhere close to that device.

~~~
Someone
It doesn’t spin that fast (linear speed) close to the helicopter, and any fuel
leaking out of the wings during flight will fly outwards so you would be safe
inside ;-)

However, I expect they pump the fuel from the helicopter body into the wings,
and I wonder how they guarantee the seal between the two. Helicopters must
continuously adjust the angle of attack of the wings, so it isn’t even a
matter of a single fixed axis, and the chemical properties of hydrogen
peroxide won’t make things easier.

~~~
regularfry
Once it's started up, it's a centrifugal pump all on its own. You don't need a
positive pressure pump on the body, the fuel would be sucked out and along the
blades like a siphon.

That doesn't make the seal problem much easier, but it at least does mean that
if a seal were to fail, it would fail safe without spewing h2o2 everywhere.

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stmw
One of the earliest efforts of this type was in 1950's, by Hiller Aircraft -
and you can see the helicopter itself in the Bay Area, in the Hiller Aircraft
museum. It achieved flight and was tested by US Navy & US Army.

[https://en.wikipedia.org/wiki/Hiller_YH-32_Hornet](https://en.wikipedia.org/wiki/Hiller_YH-32_Hornet)

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maxbaines
Seems obvious now I see it!

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pstuart
It looks cool but the last update was 10 years ago for PoC?

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gostsamo
Isn't this fuel rather toxic in case of accident?

~~~
arethuza
One of concerns would be how much of it gets converted by the catalyst - if
it's not 100% for any reason you've basically got a rotating sprinkler
throwing HTP about.

Edit: To be fair it's not HTP, fortunately for those under the flight path...

~~~
rbanffy
Everyone around it will turn blonde.

~~~
GekkePrutser
The Nazis would have loved this thing :D

