HI Frank,

I must say that I am absolutely impressed with your model!  It looks like it should be MUCH bigger!  The finish is great, and it really looks neat.

Bill <><

Thank you Bill.........

There's an idea Frank! A ST .60 gyrocopter!

bob

(if I keep this up the rest of the world is going to know how much aggivation I cause you!)

No problem Bob..........no aggravation at all...

And if you use a lite touch that same eraser will rub off overspray. You gotta go lite though.

Ray-----------why is there no pilot in your model?  Who is going to drive it?

Yeah, I was afraid you'd spot that, after the grief I gave you about a pilot being necessary...truth is, I got my heart set on a styrofoam peanut pilot and now I can't find one!  But I will, I will...

To all you guys:  Thanks for the encouragement and good words about the finish on my autogyro.  In retrospect, I shoulda just posted the pictures without all my whining, and let the chips (and remarks) fall where they may.  But I had envisioned it so much better...

Also thanks for the various tips on dealing with the raggy trim edges.  I have known of the credit-card-smoothing technique (although I will check out the nylon razor blade thingys), but really had never thought of outlining the trim with permanent marker to cover up those edges.  That might be just the thing it needs.  I don't suppose permanent pen markers are fuelproof, but a light shot of clear would take care of that. I may not be through with it yet!  Also the plastic eraser approach--I have a plane or two with a little overspray I can try that out on.  Always learning from this forum!!

By the way, concerning the positive angle of the rotor:  That is per Mr. Musciano's plan & design.  I know nothing about the aerodynamic theory behind it.  I can't quite picture how a freewheeling rotor at a negative AOA could produce positive lift (seems like it would be a perpetual-motion machine) but then there are many such things that escape me.  I suspect on this particular model the rotor is more for visual effect than anything else; the design has enough stationary wing to fly on.

And lastly, I agree: Frank's model is a knockout! Even if he is using it to brownnose Larry...

--Ray

--Ray

Yeah Ray, it took a couple days to realize there wasn't a little guy in the cockpit. I think I was distracted by all that whining and carrying on you were doing about the louzy finish. You had me psyched out. I was looking everywhere but where the little fella was supposed to be.

Try a Sharpie fine point and you'll need a steady hand to get the lines on there good. A few very lite coats of clear will fuel proof it. And speaking of fuel proof I think fingernail polish is fuel proof.

Me too on the thanks guys thing. All the times the other guys chimed in really kept me motivated and focused on doing a good job. THANKS EVERY BODY...................................

And Ray about brown nosing Larry.........I tried but it didn't work. He still wants me to pay for stuff from him..Dang!

"Thunderstruck by a bolt..." Hope it didn't hurt too much. 

Direction of rotation in front of a fan depends entirely on which way we pitched the blades; and I don't think it really matters as long as they're all the same!  And holding it at negative AOA will make the blades rotate in the opposite direction, which still doesn't prove anything I don't think. (Bad English but good Logic?)  Anyhow, we followed the design intent and plans in setting the positive angle of the rotor; in the absence of any independent knowledge at all of autogyro theory, that's all I can do or intend to do. 

All that may sound harsher than I mean it to, but all I want to do now is go fly the thing and watch the rotor go 'round and 'round...

Still awaiting my Fierce Arrow plans.

--Ray

I was young and knew little when I read that article on the model gyro but I did know the basics of airfoils and Positive AOA with wings and even helicopter rotors. I myself shot an auto-rotation landing in a Coast guard Sikorsky H-3 simulator. I was schooled prior to this of course.  The engines both were on fire and I had to first shut of fuel, hit the extinguisher buttons, put the rotor collective pitch in negative  to conserve rotor energy and RPMs. Cyclic pitch guided the steep flight path to the ground and at 500 ft altitude pulled hard on the collective pitch to flare for the landing. I did the exercise perfectly with only a moment or two being warned about coming in too steep. I was able to correct that in easy order. Ok, that made it less than perfect but I think I did pretty well!  A very memorable experience and lesson.

I have been trying to find more info and as yet have not come up with anything new to report as yet. Not done looking either.

It is my understanding that the neg. pitch creates the necessary spinning and that the rotors act more like a kite in that with the high AOA of the rotor assembly creates more actual lift than the airfoil of the individual rotors. This may account for the Blackhawk Models gyro to  in fact spin backward and yet still create the lift needed for successful flying.

Obviously this is not the end  of all this!     

The angle of attack of a helecopter is different than the blackhawk gyro because it has active collective control. The blades are constantly changing pitch and the motive vector of force must be forward for the helecopter to go forward faster. Your gyro has fixed blade pitch and to get lift the angle of attack must be positive. Direction of rotor rotation is irrelevant. Any torque force is not along the blade axis but along the axis of rotation.

Don't worry. Walt wouldn't steer you wrong. Go fly the things.... Gee Frank, Sunday might be just your kind of day! Zero and windy!

bob

Deflection, Frank, deflection...just like a flat-plate wing.  Picture a disc the diameter of your rotor; that's MOL what we have I think.  That's why it must sit at a positive AOA--or else the plane would have to fly tail-down to achieve the deflection it needs.  Well, I think so anyway...

I second Bob Branch--we shouldn't analyze 'em so much; we should just go fly 'em.  Who'll be the first to nurse one through a loop?

--Ray

Quote by Bob Branch:
"Deflection, Frank, deflection...just like a flat-plate wing.  Picture a disc the diameter of your rotor; that's MOL what we have I think.  That's why it must sit at a positive AOA--or else the plane would have to fly tail-down to achieve the deflection it needs.  Well, I think so anyway..."

This was my intention when I mentioned the kite in my last post. I am not convinced myself that this model (nor autogyros in general) should have neg. rotor pitch. I wish I could quote that article I once read...
Seems most of the autogyros I have run into appear to have positive pitch. Note I said appear. I am still trying to find the written theory to support this one way of another. 

Heh! You guys have fun! I am doing this more for me than to try to throw a monkey wrench into the works. 

It could be that the article that so impressed me was emphasizing the neg. AOA simply because it went against all the rules...
Also I was hoping you fellas already knew the answer!!!

Robert

Since I have yet to find anything substantial in writing I have taken to looking as closely as I can to the pics of full size and model gyros including a gyro kite that seems to be everywhere. The AOA seems to be rather flat and thus hard to tell whether a pos. or neg. pitch. This in itself may be an important clue. If indeed th AOA should be positive, it may actually need only to be slight.
I cannot seem to stop my search yet and even while writing this, look what I found:
http://www.autogyro-rc.com/
This my friends has a link to a video of a Kellet doing some great flying and a decent explination of how auto-giros (that is how they spelled it) fly. Using models and a real aircraft!
In this video you should see what I have been running into as far as the AOA on the rotorblades. It looks like it has none at all. Very flat. It looked to me like a semisymetrical foil but upside down? I could swear it had more camber on bottom than top! Judge for yourselves!

Clic on "How They Fly" just under the first image.

Robert   

Since I have yet to find anything substantial in writing I have taken to looking as closely as I can to the pics of full size and model gyros including a gyro kite that seems to be everywhere. The AOA seems to be rather flat and thus hard to tell whether a pos. or neg. pitch. This in itself may be an important clue. If indeed th AOA should be positive, it may actually need only to be slight.
I cannot seem to stop my search yet and even while writing this, look what I found:
http://www.autogyro-rc.com/
This my friends has a link to a video of a Kellet doing some great flying and a decent explination of how auto-giros (that is how they spelled it) fly. Using models and a real aircraft!
In this video you should see what I have been running into as far as the AOA on the rotorblades. It looks like it has none at all. Very flat. It looked to me like a semisymetrical foil but upside down? I could swear it had more camber on bottom than top! Judge for yourselves!

Clic on "How They Fly" just under the first image.

Robert   

That is extremely cool Robert! Thanks for sharing that with us!

OK fellas, I took the advice of...someone...can't remember, too lazy to go back through the posts to find it; to use a sharpie permanent marker to cover the raggy ("lettuce"?)edges of the trim on my plane.  Below are the results.  I think it looks better than it did, although still not great...I wasn't as painstaking as I could have been, just sort of experimenting around.. but, seems to me it works as advertised, cleaned up those sloppy edges pretty well. 

Now I'm setting the little booger aside 'til Spring, in anticipation of--the Next Project.  Thanks to all for the help and suggestions.

--Ray

Thanks...still waiting on more pics of your Snapper!

OK fellas, I took the advice of...someone...can't remember, too lazy to go back through the posts to find it; to use a sharpie permanent marker to cover the raggy ("lettuce"?)edges of the trim on my plane.  Below are the results.  I think it looks better than it did, although still not great...I wasn't as painstaking as I could have been, just sort of experimenting around.. but, seems to me it works as advertised, cleaned up those sloppy edges pretty well. 

Now I'm setting the little booger aside 'til Spring, in anticipation of--the Next Project.  Thanks to all for the help and suggestions.

--Ray

I thought it would help...your welcome,Ray!

Maybe this video of a gyrocopter flying will help alay your fears. Note the positive angle of attack of the rotor.

http://www.gyropilot.co.uk/ken_clip.asp

Bob

http://www.gyropilot.co.uk/

This will give you the video above and several others. All with positive angle of attack.

Bob

Excellent links Bob. I entertained myself for about an hour looking at the pictures. It's amazing how many different ways there are to make an auto gyro. So many configurations and sizes. I'm beginning to think that the BHM gyro I built is only the beginning of my involvement with them.
I find it very interesting that this airplane has such strong appeal that the thread is continuing to stay alive even after the models have been built.
I think after my initial test flights with mine I may want to increase the length of the rotors. And will probably need to build a larger version with throttle. The Kellett gyro with it's wing lends itself perfectly to CL.
Please post any additional info you find. Robert you do the same please.

Ray check out the picture of the giro. Looks like something we'd see from the Minnesota Modeler.

That's what I was thinking about Ray. That particular kit is still sitting in the to be done bin here at my house.

Thanks Frank.

Well friends and neighbors, positive incedence seems to be more and more the order of the day, yet I have not seen it in writing yet... The flapping hinge seems to be more and more important.



Robert

What is a "flapping hinge"?  Have I missed something?

--Ray

Ray, I didn't know till a few days ago.

Some of you may already know some or all of what I will say here, if so please bear with me.

A rotor craft gains its lift by means of the rotating blades. This acts like a wing to some degree.
One of the biggest differences is because each rotor is moving,
sometimes in the same direction as the direction of flight of the craft, sometimes the opposite way as the direction of flight and twice with the wind cross ways. All of this in one single revolution.
Blade behavior, will differ in each quarter of a revolution because of this. In this behavior  there is a lag time of 90 degrees.
Imagine an analog clock face on the floor .  12 O 'clock is forward motion. Or if you will the nose of our aircraft. Imagine also if you will airflow going from twelve o'clock to six o'clock.
Imagine also that the rotors are turning counter clockwise.
This will mean that the rotor at the position of 3 o'clock will have the fastest airflow over it thus creating the most lift. Just as the outboard wing panel in a control line plane has just a tad more lift than the inboard panel.

Add to this the 90 degree rule of rotor craft wherin the effect of this will be nose pitch up.
At the same time my friends, on the same aircraft but heading the other way and at the same speed of the opposite rotor blade advancing, but with a difference. It has a tail wind if you will, equal to the headwind on the advancing blade.
this takes away some of the lift of this blade.
Add to this the 90 degree rule of rotor craft wherin the effect of this will be tail moment pitch drop.
Remember that both these forces are acting at the same time.

To clarify, when flying forward, the advancing blade at 3 O'clock will cause pitch up at the 12 0'clock  position and at the same time the rotor blade at 9 O.clock will be having less lift allowing the tail to drop at the 6 O'clock position.

What the flapping hinge does, is that it allows that rotor blade having the most lift to rise upwards out of rotational line of the other blades and thus have less effect on the whole.

Whew! I feel like I am back at school! Robert

Not applicable, however, to our models wherein the rotors are hard-fixed to the hub.  Right?  And, it would seem that 0-degree incidence of the rotor should still produce lift?  But perhaps not enough, so the positive rotor angle adds the rest.  Maybe.  (Do I get an "A"?  Do I? Do I?)  "You will be tested..."

--Ray

I noticed on the old British film that the rotors were hinged, but there were wires, under tension, hooked to the hub and rotors.  (??)

Yes, a 40 size with a three line hook up would give you an excellent test bed.

Quote by frank carlisle:
" Robert, that was good!! You sounded like you knew what you were talking about."

Thanks Frank! In this case I actually do and I put it in my own words using examples as I saw them. I was hoping to paint the pictures for you in a way I have not seen tried. I also realise that this knowledge and explanation makes me   appear far morfe intelligent than I really am... While I do understand this simple theory (to me it is simple because I actually understand what Is happening.) I still do not get ( the probably just as simple theory) how the forces acting on the darned rotor  get it to spin in the proper direction thus making every thing else work!!! This of course is part of the poitive-negative angle of incidence regarding the rotor blades.
This of course is why I am doing all this research in the first place.

I am glad to be getting something out of all this so far (I actually like learning, its all this studying that is no fun!) and I am glad others are  benifitting from my studies.

Quote by frank carlisle:
"I wonder if we hinged our rotor blades if it would help or make no difference at all."

I believe you would but that does not mean that the design of this model will not fly as designed. It is my theory that flight would experience improved charactaristics but I am not convinced that this improvement would make the difference between flight and non flight.

Quote by Ray:
"Not applicable, however, to our models wherein the rotors are hard-fixed to the hub.  Right?"

Actually Ray, this applies to all rotorcraft both powered and unpowered. So I have to take off a point here. Howerer, it does seem that the smaller the model the smaller the effect has...  there are many nodels that do not have such hinges. They do fly and from what I have seen fairly well.

Quote by Ray:
" And, it would seem that 0-degree incidence of the rotor should still produce lift?  But perhaps not enough, so the positive rotor angle adds the rest.  Maybe.  (Do I get an "A"?  Do I? Do I?)  "You will be tested..."

Yes Ray! Exactly!

Quote by Frank:
" A simple pin at the rotor root would let it drift up and back down. The extra discs we made for our rotors could be made to act as stops.

I think that a larger and throttled auto gyro would lend itself better to experimentation."

Yes, and yes,  Frank! True! 

Robert

Tell us more Robert. Graphs and pictures will be a great help.
I tried the balsa strip. Sure enough it twisted it's way to the floor just like you said it would.