So many mathematical formulas in order for a gyro to fly?????

[scandtours]

I stayed home for one day yesterday, sick with cold and spend some time reading some old files saved in my computer.
Even though I did not have any headache, just fever,
reading half file of (A General Theory Of The Autogyro )
the headache started so strong that I had to take some tablets.
I thought, do really our gyros need so muchy mathematics and so many formulae in order to fly?????
The answer is yours…. I hope YOU will not get headache by reading it.


A GENERAL THEORY OF THE AUTOGYRO.
By H. GLAUERT, M.A.
Presented by the Director of Scientific Research Air Ministry.
Reports and Memoranda No. 1111.
November, 1926.

http://naca.central.cranfield.ac.uk/reports/arc/rm/1111.pdf

EFFECT OF HORIZONTAL TAIL ON THE STABILITY OF
THE VPM M16 AUTOGYRO

http://www.aero.hut.fi/pubs/reports/AALTO-AM-18elektroninenversio-2_1.pdf

 

[hillberg]

Happily the gyro doesn't know how to read & doesn't care If you hop on board for a ride. :boink:It still flys fat ,dumb & Happy like a bumble bee.

 

[WaspAir]

Yes, that's right up there on the list of probable causes for crashes from the NTSB, along with "pilot failed to maintain rotor rpm" --

"loss of lift, due to gyroplane's inability to solve second order differential equations"

 

[cbonnerup]

Happily the gyro doesn't know how to read & doesn't care If you hop on board for a ride. :boink:It still flys fat ,dumb & Happy like a bumble bee.

Luckily the bee doesn't need human intervention to fly. Imagine the chaos if this was the case! Every hive large and small with ATC...but wait

Physics (and mathematics) is what tells the gyro how to fly, extreme fun is the result.

Chris

 

[kolibri282]

It takes indeed that many formulae if you want to fly a gyro........on your computer. During my visit at AutoGyro in Hildesheim I met Dr. Holger Duda, head of the DLR Flight Dynamics and Simulation department and Insa Pruter who programs a gyro flight simulator as her PhD. I think that a good simulator could help to reduce the accident rate since you can practice things like maintaining rrpm safely on the ground before you get to the real thing. In the pictures you can see that the sim faithfully reproduces the instrument panel of the MTOsport. What you can't see is the force feedback they built into it, if you operate the prerotator you get a good kick from the stick to make things as realistic as possible. They have a very comprehensive set of flight test data for the MTO to get as close as possible to the real flight characteristics, her sim e.g. uses section data of the blade profile to calculate rotor lift and drag from local angle of attack, thus making it possible to account for stalled parts of the blades. Holger Duda is so kind as to answer a few of my dumb questions regarding my own flight sim and I will try to get a copy of Insas PhD from him and post it to the "Technical Papers" section as soon as it's finished.


PS: now that you all know that it's them math nerds who meet the nice girls, interest in the "Theory of Flight" section of the forum will surely soar!!!...;-)

 

[Monarchist]

Juergen,

I worked as a video game programmer for many years, and we never had a female programmer on-staff...they are so rare. Especially one as pretty and very obviously talented as Insa here.

I would love to try the simulator...I flew the CarterCopter simulator a few years ago and was not impressed.

-John

 

[WaspAir]

I should add that while the gyro doesn't need to be able to solve second order differential equations, I would certainly hope that its designer can!

 

[kolibri282]

I worked as a video game programmer for many years

That is very interesting, John. I am working on an autogyro flight dynamics model and one idea was to incorporate it into a sim like e.g. FlightGear. Do you think you could support me once I get to that step?

As for the simulator it felt very much the way I expected but then I have never flown a gyro and so wouldn't be able to tell the difference. Under Insas patient guidance I was even able to get the ship back on the runway in one piece, albeit somewhat wobbly on the final before touch down, but the fact that I brought it down in one piece - some might argue - is a clear indication that "reality mode" must have been turned off.....;-)

 

[Gyro_Kai]

Hello,

I have tried the simulator at the autogyro booth on the Aero exhibition 2 years ago. It feels really natural, the force feedback is impressive. I "landed" poorly on one wheel, the gyro plunged down and the subsequent kick of the stick felt very real, and I felt quite embarrassed.

Kai

 

[Monarchist]

Juergen,

Have you seen X-Plane? They've had gyro flight models for years. Here's a rather convincing video from a few years ago of an MT-03:

Gyrocopter flight at Inssbruck. - YouTube

Also, a list of some flight models can be found here.
http://forums.x-plane.org/index.php?app=downloads&showcat=53

I haven't tried these, but now that I'm looking into it (and found that they have a Monarch) I must try it.

When you say you're working on the flight dynamics model...are you working out the theory or are you writing code? What is your ultimate goal with this? I'm very busy at the moment working on mobile apps under contract so I can finish out my gyro. But I'd be happy to help where I can...

-John

 

[scandtours]

I should add that while the gyro doesn't need to be able to solve second order differential equations, I would certainly hope that its designer can!

In most countries here in Europe you need to to have aeronautical engineering
degree in order to design/build for sale homebuilds.

 

[WaspAir]

In most countries here in Europe you need to to have aeronautical engineering
degree in order to design/build for sale homebuilds.

Not so here, unfortunately. If you can sketch it or weld it, you can sell it. It's a buyer beware situation, for sure.

 

[scandtours]

Not so here, unfortunately. If you can sketch it or weld it, you can sell it. It's a buyer beware situation, for sure.

Weld it? This can be a problem, WaspAir, and I can confirm that if any parts are welded
you need a certificate from the authorised person who did the job. No unauthorised persons can weld parts used for aircraft u.

 

[kolibri282]

.....are you working out the theory or are you writing code? What is your ultimate goal with this?

I use and program existing theory, the goal is to have a program where you give some pilot input and then the complete aircraft motion and the rotor behaviour is calculated. This can be used to study flight stability, things like PPO and (if you include a pilot model) PIO as well. This sort of program is at the core of each flight sim. Since most sims were written for fixed wing aircraft, gyros and helos quite often use the same flight dynamics, which of course is rubbish. One indication of a correct gyro flight dynamics model would be how rrpm changes in low g maneuvers.


....oh, and I'll probably get there by....20xx... where xx is a pretty large number....;-)

 

[cbonnerup]

Gyro Simulation

Gyro Simulation

....oh, and I'll probably get there by....20xx... where xx is a pretty large number....;-)

Better hurry; you have until the coming solstice.:noidea:
Seriously, a worthwhile effort! Have you seen Hollmann's code for phugoid oscillations? IMHO he should make it public domain - not complete, but good to see what others have done re: this effort.

Best,
Chris

 

[kolibri282]

Have you seen Hollmann's code for phugoid oscillations

So far not. My code already calculates the stability derivatives for this but it would be helpful to compare it to what others have calculated, did Martin Hollman publish any values I could compare to?

Thanks for the hint.

 

[ckurz7000]

I know a programmer who was part of a team that wrote the code for a large commercial flight sim. He is also a gyro pilot, by the way, and visits this forum occasionally. He said that most real time filght sims don't even try to get the flight dynamics correct. Any small deviations in the numerical solution are squashed by pilot input anyway. And the computational power required to get it right in real time would be prohibitive.

I don't know if this statement still stands as it was made a few years ago. But apparently he didn't feel that then current flight sim technology would make a good platform to investigate cutting edge stability questions of the gyro.

The rotor dynamics are so much more numerically demanding if you want to get it right. It would be like a fixed wind aircraft has flexible wings that wobble and bend all the time and feed back into its flight characteristics in doing so. And, very important to gyro stability, the shift in the center of pressure with flight attitude.

I wonder, is there a good heli sim available (and I don't mean any Microsoft product or equivalent)? One that's actually used for training pilots? If yes, that would tell us that it is possible to have a meaningful rotorcraft real time sim. If no, that's a good indication that we might not be there yet.

-- Chris.

 

[kolibri282]

Some time ago I had contacted the man who had programmed the helicopter flight dynamics model for FlightGear. From what I understood his approach was similar to the DLR sim. For the rotor integration they use a few stations along the blade and a dozen or so azimuth positions plus a simplified inflow model (Peters He?), the profile data are from lookup tables so not much cpu time required here either. With GPUs today used as massive parallel vector units you have the computing power of a Cray from ten years ago under your desk so a realistic realtime sim is today well within reach. The sim is of course modular so for stability calculations you could simply exchange the real time rotor module (and others as well) with more sophisticated models. It's all there, it just takes a while to put it together.

Cheers,

Juergen

PS:

I know a programmer who was part of a team that wrote the code for a large commercial flight sim.

Could you please ask him, Chris, whether he would be prepared to have a look at my model?

 

[ckurz7000]

...
Could you please ask him, Chris, whether he would be prepared to have a look at my model?

He is not a physicist or aerodynamics specialist. He was dealing with software interfacing and integration, I believe.

-- Chris.

 

[cbonnerup]

Juergen,
I will PM you a list of parameters needed to model the system with the software I have. I can generate some drawings and perhaps some numbers to forward to you for comparison. A synopsis of the math used is located here - http://www.aircraftdesigns.com/porpoising.html

Chris

Chris