Lots of gyro questions..LONG

[Blll]

Hi all...

New member to this forum...

About 2 years ago I developed a real interest in gyro's and basically read everything over at Mels gyro forum...and I never knew about the now apparently defunct Norms forum...my interest has returned and this looks like the place to be and ask questions when it comes to gyro's...

So, here comes lots of questions and observations....input on any of these is highly appreciated....Now since I cover a lot of different topics if you choose to respond to any of them it would probably make sense to place your responses in the appropriate forum section with the appropriate thread title and just note which place you put your response...Thanks!

Okay, one of my main reasons for interest in a gyro is my impression that they are a lot less sensitive to air turbulence than light or ultralight airplanes....and I'd hate to have an expensive toy that the weather has to be nearly perfect to use....I live in Northwest Florida.....any flyers in Alabama, Georgia, or Florida here who can comment on how often percentage wise the weather in the southeast is suitable for gyro flying? Note that most of my flying would be in the few hours after sunrise and the few hours before sunset and typically 50 miles or more from the coastline....

I recently downloaded Jukka Tervamaki gyro simulator/calculator.....at :

http://www.icon.fi/~jtki/gyrocomp.html


its pretty cool and his website is nice as well....one caution....on some computers his simulation ONLY appears to work in the metric mode (dont bother to notify him about it because I already have and he is working on fixing it)... the really neat thing to do with the program is to change one parameter at a time in small increments without clearing the screen and you can see whats important and whats not and when you reach a point of diminishing returns....for example, input the values for a small, low drag gyro, then start with a small prop....something like 46 inches, then increase it in say 4 inch increments up to say 80 inches....and you can easily see where making the prop bigger doesnt really buy you much more if anything in your top speed......note that when you first run the program you have to be online for it to download the data it needs....once that is done, you can get offline and run many calculations....but once you close out the program you will have get back online again at first the next time you use it....

Now with his simulation, with as low a drag gyro as is possible....the program predicts that a 500 lb gyro (26' ft, 8" chord) rotor, with 33 hp at 2083 rpm using a 64" prop will go at a speed of about 85 miles per hour....does this sound doable?

The reason I ask is I would really be interested in a small, fast gyro for short, quick, hops to visit places I often go to on weekends anyway, places that wouldnt be bad drives except for the fact that I have to usually fight my way through at least 2 congested towns and there are no direct fast roads from here to there...and even if the gyro wasn't much faster than driving...an hour or two of flying would be a lot more enjoyable than the same amount of time in stop and go traffic ....fortunately there ARE small, conveniently located airports at where I'd be leaving from and where I'd be going to ...Now if I could have a small fast gyro that could do 70 that would work, 80 would be pretty nice, and getting near 90 would be the cats meow...

I understand that due to the rotor aero/dynamics, a shake/vibration is transmitted down to the control stick (even with perfectly aligned/balanced rotors)....is this something that is just noticeable...or is it something that after an hour or two of flying has you just plumb worn out mentally and physically?


The asymmetry of the forces due to the rotor dynamics...now if you have a 500 lb gyro in level flight.....its obvious that at some point each rotor is supporting exactly 250 pounds...however at some point in the rotors orientation the different in lift between the rotors reaches a maximum....roughly what is the magnitude of this difference? 5 lbs, 20 lbs, 50 lbs.....? In which direction is this "shake" at its maximum? Side to side, front to back, or somewhere in between? Is this "shake" mostly caused by the fact the rotors can only pivot up and down around one point (the teeter? bolt)?...or is it mostly caused by the dynamics of flexible blades? or is it a comparable mix of both? Would more flexible blades (though still sufficiently strong) make the shake better or worse? And for this group of questions let us assume level, steady, flight and stable rotor rpms....

Rotor blades......what are the lightest ones commercially available and what are the heaviest? And how much does each weigh? And how much does you typical single seater 500 lb range gyro's rotor head weigh (not including the mast)? ...trying to get a feel on center on gravity issues here....

For your typical constant chord, no "twist", constant airfoil cross section gyro rotor blades...what is its lift to drag ratio.....i.e. what would a gyro's lift to drag ratio be if the mast, passenger section, landing gear exceterra had ZERO drag...is there a forward speed that it reaches a maximum? At what forward speed does it start to drop drastically (ie drag is increasing quickly) ?

Now, if you made a rotor system that DID NOT have a constant chord, or constant airfoil cross sections, or constant angle of attack (ie it has a "twist") along its length....roughly how much improvement percentage wise could you hope to gain over the rotor describe above? Obviously such a rotor would probably only be "optimum" for one set of conditions....say rate of climb Y at speed X or maximum lift to drag ratio at cruising speed Z......

Is there a rough way to calculate your vertical descent rate in autogyration mode? Or does anyone here have the rough numbers.... (this would be handy for calculating/designing the landing gear system)...

Landing gear.....how much vertical travel does the typical gyro landing gear system have designed in? Say something appropriate for runways of decently smooth grass or smoother...

The engine propellor for either tractor or pusher gyros....how close to the ground can the propellor tips get in normal operations or hard landings before it feels/seems uncomfortably/unsafely close to the ground?

Well....

Thats probably enough questions for the moment!

take care and thanks again for any input!

Blll

[quadrirotor]

http://www.aircraftdesigns.com/

[joeheli]

Bill, I know how you feel , I just have 2 month in the forum ,and I have been asking many Question and you are wright this is the place were every one here will always help you, so you are in good track!! . The other thing that will help you is to take a demo in your area, Ask any question to the CFI (pilot instructure) they will be glad to help you. This week starting today, in Florida they have the Bensen days there ,you will see alote of gyros and alote of CFI that will be glad to help you will all your question. Is not that I don't want to answer your question is that I learn that you can ask many thing (like I use to do )but is not the same explaning it to you that the real world. The only think that I think it will help is
That take a question one by one ,becouse you will be confuse and scare and we don't want that . . About your question that the gyro is less sensitive to air turbulence than light or ultralight airplanes, you are wrong the gyro rotor blade act like a wing, you will fell turbulance like any other aircraft. About planning to get a gyro that will cruse 70, 80, 90 mph you will be better if you buy a plane. Gyro normaly cruse 50,60, and maibe 65 mph, they are not desing for goin fasttttttt!! and if they do the will cost you 80K,90, or $100,000. I hope you will go to Bensen days, I will go and more experience pilot will help you and you can experience a real fly with your first demo.

[ToddP]

Originally Posted by Blll

Now with his simulation, with as low a drag gyro as is possible....the program predicts that a 500 lb gyro (26' ft, 8" chord) rotor, with 33 hp at 2083 rpm using a 64" prop will go at a speed of about 85 miles per hour....does this sound doable?

Billl,

First, Welcome aboard, the best thing you can do is ask questions and search through the old posts.

I won't try to answer all of your questions, but I will tackle this one. From limited real world experience, I don't think your real world gyro is going to give you anywhere near the performance your simulated machine is. There are several problems here:

1. Obviously the design is very streamlined, streamlining requires body pods, wheel pants etc. You will never make a 500 lb. gross weight streamlined gyro.

2. Jim Vanek makes some 8" Chord, very large blades, but I don't know of any others.

3. If you've ever seen the Dan Donley tapes, there is a line from Ken Brock thats said over and over "rotorcraft are draggy devices, very draggy". That big 26' 8" chord rotor will never go 85 mph on 33 hp.

4. To sum it up, it does not sound "doable".

For comparison, A dominator gyro, with pod and rotax 582 (64HP), 25' Rotor Blades, will probably not maintain level flight at half horsepower (close to your 33 hp). For some reason my dominator ended up really heavy (Ernie thinks theres lead in the tail ). The dominator with nose pod is supposed to weigh about 350. With pilot and fuel you're going to be at least 550, probably closer to 600. It will take nearly full power to reach 85 mph in level flight with this machine.

[rehler]

Bill and others,

I have learned that it is best to ask only one question at a time. Keep the post short and easy to read. This will get a lot of answers from several people giving a broad perspective.

In general long posts get few answers. People just don't want to spend the time to read longs posts and then spend more time answering a lot of questions a one time.

[scottessex]

If you already are in Florida, go to Wachula this week! and check out Bensen days. You can take pictures, ask questions, get a ride, get brochures, and see alot of different styles of gyros. I understand your enthusiasm, but go for a ride, take some lessons, and then you will start to understand, and MANY of your questioned will be answered just by your experience with flying one of the machines.

[KenSandyEggo]

Ken II is correct. Just ask a couple questions at a time for best results. Actually, gyros handle turbulence better than any other aircraft. Helis power through it, because their rotors are powered, but they feel less turbulence than fixed wings, but more than gyros. Gyro's rotor speeds adjust constantly in flight. On average, I'll see anywhere from 305 to 345 during a flight as the blades change speed to adjust to the wind. I believe this may be spelled out in the FAA Rotorcraft handbook. If not, I don't know where I heard this. Someone help me out. If I'm totally wrong on this...........never mind.

[Harry_S.]

Right you are K.J.

Wind,weight and g forces.

[quadrirotor]

BIII, it's for you.
http://www.viewaskew.com/tv/leno/flyingcar.ram

[Hognose]

André,

It amazes me, this stuff you find. If you haven't already, check out the stuff Mike Hirschberg did for AIAA. He's done some very comprehensive work on VTOL craft.

cheers

-=K=-

[quadrirotor]

Hognose;
I don't know what Mike Hirschberg did for AIAA.
can i have any references?
thanks.

[Al_Hammer]

quadrirotor,

he did the "WHEEL", a huge chart showing all the VTOL machines...
http://www.aiaa.org/tc/vstol/wheel.html

[quadrirotor]

thanks a lot.

[Hognose]

He did a lot more stuff while he was at ANSER (a beltway bandit). Unfortunately I think ANSER took down Mike's work from their website, which is a pity (he was working on a project related to the VTOL F-35 Joint Strike Fighter; when that rolled up he went to a different outfit).

He has also written a book on German VTOL developments to 1945. This includes helicopters and some of the ahead-of-their-time convertiplane proposals. It's part of a multivolume comprehensive history of VTOL.

cheers

-=K=-