Stopped Rotor idea

[Dave_Jackson]

OTHER: Miscellaneous - Thoughtless Ideas - Stopped Rotor
Criticism begrudgingly appreciated.


Dave

[SASless]

Dave,

You really do need to get out more....really!

[gadgetguru]

X-wing

I remember seeing one of those technology documentories where they had a concept helo (around the same time as sikorsky's ABC & the Grumman? X29a) that was a 'X' wing, rigid blade helo that at a certain point the blades slowed & locked into position allowing the forward speed to increase beyond normal RBS speeds.
don't think it ever flew, but it did make it to the drawing boards.

but then - so did 'the homer'

[Dave_Jackson]

SASless,

I do get out; every time the dog has to pee.


gadgetguru,

Yes, they never flew the X-wing. Probably because it lacked lateral symmetry.


Dave

[sprocket]

Dave, Cessna achieved this state of advanced rotor technology some years ago. The pic below shows two fixed rotors which are simply attached with a couple of bolts on either side of the fuselage. They even have a rotor on the front to provide forward motive force while the fixed rotors are ..... fixed.

[Graviman]

Dave, i assume this concept is applicable to roles where the cost of the machine does not have to justified against the payload it can carry?

We were discussing compromises. The one i see here is the need for structure to carry the moveable rotors - ever wonder why no commercial plank has ever been swing wing? Completely stopping a rotor is also a bad idea, the front rotor only protection against catastrophic structural divergence is to have an airflow moving over it. Either that or you also need to consider spanwise flexural control - how compromised is that!

Mart

[Dave_Jackson]

sprocket,

Are you 'giving me the gears'. Your link won't open.

Mart,

no commercial plank has ever been swing wing

Could your and sprocket's postings be in conflict?


Dave

[O27PMR]

Dave

I don't want to sound rude but what's the point???

The design looks interesting but I don't really understand what it is trying to accomplish?

Would there be any advantage in having such a machine or is it just an interesting theory?

PR

[Dave_Jackson]

O27PMR,

This idea is just one of some 'thoughtful' and many 'thoughtless' ideas related to laterally configured rotorcraft. Ideas breed ideas, and the hope is that this work will expand the knowledge and interest in these configurations.

In addition, these posting are intended to put the ideas into the public domain, so that WHEN the superiority of laterally configured high-speed rotorcraft is realized, no latecomer to the party can patent these higher-level concepts; to the exclusion of others.

___________________________

For consideration;

In 1848 Sir George Cayley 'the father of English aeronautics' proposed a helicopter with; laterally located main-rotors, rigid rotors, high rotor solidity, and pusher propellers.

In 1941 Anton Flettner produced the technically successful Intermeshing FL-282s.

In 2000 W.Z. Stepniewski stated that the Intermeshing ABC configuration appears to have the highest potential for the future.


No one would dare to question the technical competence of these three men.

However, one might wish to question why the fan-on-tail configuration has dominated.

Dave

[O27PMR]

Thanks for that, makes more sense now.

I have just had a quick punt around your website and it looks very interesting and definitely thought provoking.

PR

[Graviman]

Originally Posted by O27PMR

I have just had a quick punt around your website and it looks very interesting and definitely thought provoking.

One thing that can be said, Dave does provoke thought.

Mart

[heli1]

The original stop rotor project was the Sikorsky S-72,with ejector seats and an S-61 dynamic system initially.Two were built and at least one flew in fixed wing mode ,using its ancillary stub wings etc but they never pursued the actual rotor design to the flight stage.
More recently Boeing has been developing the X-50 Dragonfly ,which was a scaled RPH but again was abandoned when they kept running into control difficulties.
Personally I think the tilt wing is a better bet!

[slowrotor]

Stopped Rotor

Dave,
Danish pioneer Jens Ellchammer, in 1914, built a coaxial with the lower rotor central disc covered in fabric to serve as a wing or even as a fixed parachute.
I think it was the first compound helicopter. Made hops only.

[slowrotor]

Boeing is still working with the stopped rotor idea:

Ares Homepage

I am working on the stopped rotor idea also. Not for high speed, as is usually the goal, but as a means to obtain slow flight for a small airplane.

I think it would be called: "Stopped Rotor Compound Airplane"

[slowrotor]

Dave,
This 2007 patent seems to employ a "stopped rotor"
Convertible aircraft operating method - Patent Application 20070170307


The fold process seems rather unlikely in my opinion. As we know, a patent is no guarantee of success.
The inventors name is Cierva... perhaps a relative of the original autogyro inventor.

slowrotor

[Dave_Jackson]

slowrotor.

Here are some rambling thoughts, for what they're worth.
__________________

Re your old, and missed , Stopped Rotor posting of Dec 16, 2006.
For the interested here is a picture and paragraph on Ellehammer's helicopter from page 8 of Leishman's book. One or two others have promoted this idea since then. This is a video of Vranek's concept. The use of the relatively unproductive center portion of a rotor disk as a 'wing' or 'lifting body' is interesting. However, in forward flight the rotor-disk would have to be tilted forward and the 'wing' must be tilted back. Incidentally, Nick was not impressed with the Disk Rotor.

Here is a later PPRuNe thread on this concept.
Here is a related patent, which I just stumbled upon.
_____________________

Re the Airs/Boeing craft.

It is interesting. However it also seem to be very 'busy' with 5 rotors & propellers, plus 2 pair of wings. How easy it is to be critical

You might, and then you might not, find something in this idea. It has been the current project for the past couple of days and it is an attempt to simplify the AeroVantage

Some noteworthyless points.

• The wings, or at least the root ends of the wings will rotate with the PropRotors.
• The large rotor might be stopped once the transition to forward flight has been made and used as a partial wing (canard?), since the single propeller can provide all the necessary forward thrust.
• A gas engine might rotate with the Propeller(s). The center of lift of the wing would therefore be further ahead of the center of lift of the hovering rotors.
• The torque of the two rotors might be reasonably well balanced, with the ailerons on the wings compensating for any difference during hover.
• Enough rambling for now.

_____________________

Re posting #
Here is Cierva's Patent application, c/w the drawings. It appears that he did not continue and file a full US patent.

This is the Carter concept and it doesn't do anything for me.


Dave