A New & Efficient High-Speed Rotorcraft

Thank you jlawren3 your prayers are appreciated.

Only problem is that the surgery ended up getting candled at the very last moment. I was all done up in the surgical gown and just about ready to go to theatre when they realized that there had been a stuff up in the paperwork and that they had forgotten to do what's called a Pre-anaesthetic Work up which takes a couple of days to complete. Without going into the details the end result was the surgery was cancelled and will hopefully be done next Thursday. The surgeon wasn't too pleased either because he came in specially today to do my surgery and ended up sitting there twiddling his thumbs wondering where his patient was.

Will the surgery correct those awful veins in your avatar eyes?

After today's balls up they're even worse.

Who said that people in Germany can't have a sense of humor?

Gosh what a Brit you are

Get more wellera soon masu. Those ugly eyes will see but ugly planes will never fly efficiently, not for fuel and not for skills.

Ky.

Thanks!

From jlawren3's subsequent comment, he automatically takes the LH diagram to be both rotors.

Anyhow; to chat through this "belief";

You observed quite early in the piece, that to do this symmetrical blades would be required - I fully agreed as I had the same thought.

I subsequently roughly sketched out the pitch angles through the cycle.

To actually get upward lift out of the up-going blade, requires reversed pitch. ^{_{<confirming 'symmetrical' camber'}}

It might lend itself to an elliptically geared continuous rotation approach, where the blade [axis] rotates 1:1 with rotor revolutions. ^{_{<not only 'symmetrical' camber, but 'fully symmetrical'}}

However; this reversed pitch is also reversed thrust.

_{(And so I came to the 'stalled/drag' conclusion for the down-going horizontal blade, and zero attack for the up going partner, as either way the blade passes through zero pitch to effectively stalled in reversed thrust.)}

Will if fly? given power, yes vertically. Will it fly axis horizontal? No. Nor I warrant could the model, and less so with any increase in mass/payload/power plant.

Nor am I sure jlawren3 appreciates, that though we are taking this from different perspectives, that we are in fundamental agreement on the basics.

ga. I agree with all the others. I enjoy reading your explanations.

"You're stuck with using a symmetric aerofoil the only control over which you have is its airspeed and angle of attack and that's going to severely limit your aircraft's performance"

If scimitar shaped rotor blades are used, would they not increase the chord length at longer radii ? Just curious... I don't know much about them. the wiki says they are used to help with the sound barrier issues. (I know that my profile is shaped differently than the regular ones, but would have lower drag closer to the body I think)

chris

Hi Chris,

On the one hand scimitar-shaped rotor blades might invite less trouble with problems related to the speed of sound, but I do not think that they will be needed because I do not expect that the rotor blade tips will be operating near the speed of sound.

Here is a backward way to conclude that. Suppose that the craft is flying at, say, 250 Knots. I have shown earlier that in that case the rotor blades would be making long slow spirals through the air with their speed only marginally higher than the 250 Knots in this example. This is to say that the rotor tip speeds will be a lot less than the speed-of-sound. Even so, it would be wise to make the rotor blades thin, particularly at their tips because it is best to stay far from speed-of-sound problems. And near the rotor blade tips not much thickness is needed in the rotor blades anyway because the bending moments produced in the rotor blades as a result of the aerodynamic loads will be low because the moment arm applying the bending loads is short.

I also think that scimitar-shaped blades would probably introduce their own problems. For one, the centrifugal (and centripetal) forces are high. By using straight rotor blades one prevents the centrifugal forces from stressing the rotor blades unevenly across their width.

A curved or scimitar shape in a rotor blade will almost certainly result in a twist being induced in a rotor blade when a load is present. That would undoubtedly result in changing the shape of the load versus radius function that describes how the load varies with radius. But I can't right now think of a good reason to make that function change with the rotor blade load.

jlawren3

"each rotor blade aligned with the flow when it is vertical and given a small angle of attack when it is horizontal"

John,

I finally got what you were saying I think.. and it seems problematic to me.

In order to become aligned with the flow, each rotor will have to pass through stall 4 times for each rotation. This will create drag and loss of lift 4 times per rotation per rotor. I think that also the stall wake from the front rotor will create severe problems for the rear rotor, especially as the rear rotor will also be stalling 4 times per rotation itself.

It would seem simpler to have winglets and keep the rotors AOA under the stall angle.

Chris

ps.. my 45degree image shows the rotors increasing past stall, but only to 45 degrees each.

• "You guess correctly - yaw is an aileron like lift vectoring when the wing is 'vertical'.

The only problem with that concept is that with the V-22 Osprey the wings always remain horizontal, only the engine nacelles tilt.

• "That aside; I still don't see how the OP's design is going to fly anywhere near 'horizontal' with out some 'body-lift' geometry, or other lift surfaces to 'pivot forces around'."

I agree wholeheartedly and believe that without some sort of wings the best that will be achieved is a sort of 45° to vertical horizontal motion which will totally screw up the supposed 19:1 L/D ratio.

when the wing is 'vertical'

huh? only the engine pods turn vertical I thought?

Chris,

I don't follow your question. On the tiltplane.com website I see no engine pods.

The craft is assumed to have engines inside it. They would, of course, change their orientation with the orientation changes of the craft.

John

no, the pods are on the V-22

Poorly expressed on my part - meaning 'vertical" in respect to thrust

"The entire rotor, transmission and engine nacelles tilt through 90° in forward rotation and are directed forwards for forward flight, and through 7° 30' in aft rotation for vertical take-off and landing."

I.e. the thrust is vectored with respect to the chord

VTOL is hard. The complexity of the V-22's is evidence of that.

Tiltplanes use, I believe, an approach to VTOL that is simpler than the approach used by V-22s. I found out that V-22s implement cyclic pitch and collective pitch on both rotors and they also have the added degree of freedom of needing to change the pitch angle of the rotor/engine pods. Tiltplanes also need to implement cyclic and collective pitch on both rotors but there is nothing to compare with the need to change the pitch angle of the rotor/engine pods on V-22s.

Well, on the other hand, there could be. I was once advocating that tiltplanes be used to transport people and that it would be attractive to design those tiltplanes so that, after they land, they could fold their rotors and essentially kneel down so their fuselage is close to the ground so people could easily get in and out. But I was unable to find a design approach to do this that was simple and straightforward. Everything I considered was certainly a lot more complex than simply tilting the rotors on V-22s.

I am currently thinking that early applications for tiltplanes will not be carrying people.

jlawren3

"Everything I considered was certainly a lot more complex than simply tilting the rotors on V-22s."

You obviously haven't seen a V-22 Osprey folded up ready for storage below decks. Have a gander at this picture and tell my your concepts were more complex.

GA.

Really great picture and diagrams....thanks.

I never knew it could do that! wow.

GA.

Pretty aircraft. Did the small version actually take off and fly already? Do you have a weblink?

1) Has wings, so it will fly horizontally using less far energy. Control (pretty conventional I expect) will not be a problem.

2) Has wings, engine torque will have a far lower effect due to these "stabilizers".

3) Two engines, automatic nulling of engine torque when both in use.

4) seemingly a mostly conventional technology (fast and easy development) with no retracting propellers, no "flying on the props as airfoils" etc etc.....development time will be really short in comparison.

5) Money will be no problem coming from NASA, private investors will not be involved (other than via the taxman of course!).

6) C of A will be no problem, company has a long record of flying very complicated large aircraft, even out into space, the moon and beyond for more than 60 years.......with remarkably few errors! (The competing company in Russia has kept a lot of failures secret!!!!)

7) 100% not a scam. (Has not posted themselves on CR4 either!!!)

I'll buy it!!

The weblink is tiltplane.com. Please see my paper there.

Only toys have flown already. In figure 4 of my paper a toy is shown consisting of a stick with mountings for two propellers, one at each end. One propeller is held while the other propeller is used to wind up the rubber band between the two propellers. When the toy is released it darts for perhaps 50 feet at high speed.

The flight path of the toy illustrates some of the craft's flight principles. The flight path of the craft is a fairly straight line, whether the craft is launched horizontally, nose up, or nose down. I say that "fairly straight" because one can observe small direction changes as the craft passes through small air currents. After a direction change the craft seems to have no "memory" of the previous direction. From this type of flight path one can conclude that the model has neutral directional stability.

The craft works fine without added stabilizer wings. Such wings would add drag.

The torque and power required are reasonable. I have computer programs written by Ray Prouty which can be used to predict the flight performance. One has to specify virtually everything about a trial aircraft. One design I studied had a lift/drag ratio of 19:1 at about 195 MPH, which is quite good. Airliners also typically have L/D ratios of 19:1. If I make the rotors longer or narrower I expect that I can achieve a somewhat higher L/D ratio.

I need to apply to NASA. Do you have experience in doing that? If so, can you to help me with this? Might your company help with the model building and wind tunnel testing?

I don't understand your point (6). What is C of A? Who are you? What company are you speaking about? If it is the company you are a part of, what company is that?

jlawren3

John Lawrence

Lawrence Engineering

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Just found a load of webstuff (and your link too) thanks.

What happens if one propeller stops?

I expect that there will be a single engine or power source driving both rotors through gears, so it should not happen that one rotor would stop turning.

Curiously, I expect that when the craft is cruising if it were somehow possible to disengage one rotor and lock it so that it did not turn, then I think that the craft could cruise well enough with propulsion being provided by the other rotor. But when hovering, and during the transition process between the hover and cruise modes, both rotors must be turning.

May I ask as to how you would prevent the fuselage spinning in the opposite direction to the propeller, with one prop switched off? I do believe that someone else mentioned it earlier and you haven't answered him as far as I can see either....I have also asked this question before to no avail.....

Torque reaction is so strong that even on normal prop aircraft (with wings and a tailplane to stabilize) that with hands off, a single engined conventional aircraft will make a strong turn opposite to the direction of the prop turning. Its a welknown and fully documented effect that constantly changes with the speed of the prop rotation....

Multi engine prop aircraft have the engines on one side turning in the opposite direction to those on the other side to negate this very strong effect.

With your huge props, the torque will be far larger and therefore turn the aircraft cabin into a giant centrifuge!!! You have no wings or other stabilizers to prevent rotation.....

The ONLY reason that the simple rubber band powered model works, is because if the props are identical, but opposite in thrust, they bot get exactly the same torque (assuming no high resistance bearings) and turn in opposite directions, thus the torque from one cancels the torque from the other, then that would work.......to a degree at least. But I bet the fuselage revolves even then......

You have demonstrated to me enough that you are not an engineer, nor do you possess "common sense" engineering understanding (which many great unqualified Engineers have had in history).

If you posted here exactly when and where you attended university and what you studied etc., I am sure that a few here could check up on that and verify your qualifications.

If you are a qualified engineer, you do need to go back to school and learn some simple basics again.......

Anonymous Poster #1,

I attended Webb Institute in Glen Cove, NY and graduate with a BS in Naval Architecture and Marine Engineering in 1964. Please feel free to verify that. (My name is John Marshall Lawrence.)

In normal operation both rotors would generate equal and opposite torques.

The craft cannot operate with "one prop switched off". The two rotors or props must be turning in opposite directions; typical operation would have them turning at the same rate.

When cruising one rotor could be stopped, but the stopped rotor blades would need to be given appropriate pitch angles so that the stopped rotor could resist the torque produced by the turning rotor.

I agree with you about the two-propeller, rubber band powered stick model: it is unlikely that the torque of the two propellers would match exactly which would result in the fuselage turning a bit as it flew. But in my proposed craft the pitch angles of the rotor blades in the two rotors would be under servo control so that their torques would be made to continuously match, even as the rotor speeds changed. When the craft is hovering the requirement to make the two torques match is no different than what is done in dual rotor helicopters. There should be no difficulty in continuing this torque matching function into the transition and cruise modes.

jlawren3

You are changing your mind and your tune......picking up on comments from your critics....

This demonstrates that you had not properly researched the design fully when you had posted.

Just think about the drag that will be caused by the offset still blades, efficiency will be zero.

You need to prove the theory before starting to collect funds from believers, if you are to be taken seriously (don#t give up the day job!).

Build a model and get it flying with first two engines, then one switched off....program PICs for the features needed particularly safety ones, they should be totally automatic.

The PICs are very small.

.......invest say $500 and prove the theory yourself.......take a video and publish that!!! You will have far more people believing in you than at present!!!

Till something flies properly and can be fully demonstrated that it can be steered and is at least as safe as a Chopper, you will not get your business "off the ground!"

I feel slighly disenchanted to see that nobdy mentions The Duranopter that is in priciple similar to this machine but, having part of the blades parallel to the fuselage, they show a high lift in horizontal flight. The flight parameters are near perfect.

Another thing is the real practicability of tailsitters

http://www.youtube.com/watch?v=Z59qISgdRp4

http://www.youtube.com/watch?v=_jCkreQxob4&NR=1

chorete

Chorete, we did mention you. See #31 from this thread. It was another discussion about this same idea.

The Duranopter has some similarities to this idea. I still think there is some money to be made with a toy Duranopter. Have you pursued that?

When I first saw the Duranopter in flight on the website you mention I was very intrigued, but the design does not lend itself to practical applications as far as I can see.

jlawren3

more specifically on that thread, I mentioned it on post #31

Very few times I have been involved in such a complicated discussion.

It has become so complex simply because it seems that nobody is able to understand the principle of the Tilter, including the inventor itself.

I have been trying to write some clear explanation, but it would take many sketches and videos.

The REAL tilter was invented by a Geman Scientist of the 20's and it was based in a totally incredible aerodynamic effect.

Take a standard aircraft wigng and rotate it around an axis in the noirmal directrion the flight.

The result appears at first sight to be crazy. You MUST get tremendous drag because the wigns rotate perpendicular to the relative wind ( That is with an angle of attack of nearly 90º). But he made a marvelous mathematical study demonstrating that this this was NOT the case. On the contrary the aerdynamic efficiency of the wing was far superior to the combination of a fixed wing and a propelle. Bu he went far and made marvelous models demonstrating the fascinating flight capabilities of the invention.

I show a Gyroplane I made shortly before discovering the work by the German Scientist.

I promise to try to find the videos of the German.

That was a REALLY wonderful Tilter (Tailsitter)

Mine is a normal lander.

chorete

Sorry I cannot insert any picture

Can anybody tell me why I cannot insert any picture in a message?.

Pity, because the "Gyrocopter" by Erich von Holst, later developed by us, will sent a brilliant ray of enlightment to this so confusing and confused forum.

chorete

What format is it in? Best is .jpg.....

Then it should not be a problem......

When you say "gyrocopter" are you talking about something like this

or something else?

By the way to insert an image all you need to do is click on the image icon in the toollbar above the text window that looks like this

Dear Admin.

Can we get the images shrunk a bit so this thread doesn't require my entire screen to follow who is saying what to whom?

Thanks in advance

Sorry about that, unfortunately I can't reduce the size of an image once it's posted. The images I posted used direct URL links and they ended up being bigger than I anticipated. What I'll do in future is download them to my computer first then post them from my there. That should ensure they aren't too big but it will result in a considerable loss in resolution.

Build it.

No disrespect intended, and I note that you are seeking advidce. Good. The 'proof is in the pudding' as they say.

You have had a bit of a beasting here from some posts, though it has been mainly constructive. May I suggest it is now time to seek help in getting this project off the ground. Even a rough and ready prototype would be something. There comes a time when you simply have to get the financial backing and work your idea. I'm no aviation expert, but well done for arguing your corner. I have learnt a huge amount from masus's posts (and yours)- thanks to you both.

Kris,

I think that you are right. I am signing off for now.

jlawren3

Come back with a progress update. CR4 is not always as harsh as it seems. I for one would love to hear how you get on, and shall keep this topic subscribed. I don't know the techno stuff, but trying to do what people say to be impossible is no bad thing. My suspision is that this does not work, but get to a build stage would be a wow. A very cool thread. Thank you and best wishes. Even if you can't make this work, you have got people thinking. Very cool.