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Old Dec 29, 2006, 06:28 PM
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Originally Posted by mnowell129
Ari,Dan,
A little theoretical knowledge can go a long way. I'm sad that you guys have time invested (at least mentally in Ari's case) in something that might not work. I hope you don't see me as being negative about this, I'm just trying to explain why things the way they are.
There are some folks that will go ahead and try something even though there is fairly convincing scientific theory that it won't work. I'm just one of those that would rather try something that the theory says has a good chance of working rather than not.
Have a good weekend.
mickey
Mickey,

No worries mate. I love experimenting. I learn far more doing this than if I just "plug and play". You are absolutely right about the theoretical knowlege, that's why your posts are so valuable. Having experimented, I'm able to grasp the theory a bit easier.

Plan B for the GyroStick is to have the spindle tilt for roll and a simple way to hook it up to the rudder servo...unless a better plan B comes along.

Dan
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Old Dec 29, 2006, 06:44 PM
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Quote:
Originally Posted by mnowell129
A little theoretical knowledge can go a long way. I'm sad that you guys have time invested (at least mentally in Ari's case) in something that might not work.
Mickey, you're the source of most of my theoretical knowledge. Your explanations saved me much aggravation with my experimentation over the time I've been reading this forum. Looking forward to more enlightening information from you!

Ari.
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Old Dec 29, 2006, 08:04 PM
Mickey from Orlando. Really.
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Quote:
Originally Posted by leadfeather
Plan B for the GyroStick is to have the spindle tilt for roll and a simple way to hook it up to the rudder servo...unless a better plan B comes along.

Dan
I think after all this writing I've concluded that tilt for roll, elevator and rudder is the simplest way to go with the best chance of success. I'd use aileron for roll, rudder for rudder and mix in the transmitter or just fly the rudder myself.
If you get the lateral area right you could skip the rudder but it makes it so much more controllable on the ground and in the turns. Anyway, good luck. I'll try to keep writing.
I really appreciate the feedback from you guys. Keeps me from thinking like I'm talking to myself.....
mickey
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Old Dec 29, 2006, 08:20 PM
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Mickey,

In order to avoid overloading the servo hooked up to the spindle for roll control, do you think putting a v bend in the control wire (which will act as a spring) would work? My guess is that it will make roll more sluggish, but hopefully it will soak up the loads.

Dan
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Old Dec 30, 2006, 03:07 AM
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This is a great thread, hope that it becomes a sticky soon.

Dan, you won't be surprsed that I agree with Mickey when he concluded "that tilt for roll, elevator and rudder is the simplest way to go with the best chance of success". This is also consistent with my "keep it simple" philosophy.

On the servo loads for the roll spindle issue, I just use a normal low torque (0.7kg/cm if I recall correctly) 6.5 gram Towerpro servo with a direct link to the rotor control horn, and that seems to be fine on my single rotor autogyro.

I suspect that if you put a spring in the control linkage, it would cause more problems than it would cure.

Al
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Old Dec 30, 2006, 05:11 AM
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Mikey, what do you think about V-tails? A 3-channel, flybar-stabilized model with no tilt control and a V-tail?

From what I'm reading here, I'm pretty confident an aileron/elevator model would work because ailerons would induce cyclic roll much like "direct" tilt, but that will require wings :=)

Ari.
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Old Dec 30, 2006, 05:18 AM
edi
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I still didn't get why the right rudder induced a mast tilt to the left and therefore, left-cyclic pitch ...
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Old Dec 30, 2006, 08:25 AM
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Quote:
Originally Posted by iter
Mikey, what do you think about V-tails? A 3-channel, flybar-stabilized model with no tilt control and a V-tail?

From what I'm reading here, I'm pretty confident an aileron/elevator model would work because ailerons would induce cyclic roll much like "direct" tilt, but that will require wings :=)

Ari.
Ari,

This is something I have in the works right now! Amazing! On another project (hydrofoam) I'm working on, I used an inverted V tail. It is a very flat v but gives enough yaw control for taxiing, and in the air give more roll than yaw. I am planning on using this taileron set up on the next evolution of Cyclone. The next evolution was also going to use a single rotor. This is why I am doing the GyroStick project, to learn about single rotors.

Here is a short video clip of the flat inverted V tail demonstrating good taxiing yaw control.

http://www.rcgroups.com/forums/showt...83#post6574889
Version 2 is more like what I will be using in the gyro.


I think the concept of the inverted V tail should work and has the benefit of being 3 ch as you stated and still allowing steering on the ground.



Dan
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Old Dec 30, 2006, 08:45 AM
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Originally Posted by alfoot
This is a great thread, hope that it becomes a sticky soon.

Dan, you won't be surprsed that I agree with Mickey when he concluded "that tilt for roll, elevator and rudder is the simplest way to go with the best chance of success". This is also consistent with my "keep it simple" philosophy.

On the servo loads for the roll spindle issue, I just use a normal low torque (0.7kg/cm if I recall correctly) 6.5 gram Towerpro servo with a direct link to the rotor control horn, and that seems to be fine on my single rotor autogyro.

I suspect that if you put a spring in the control linkage, it would cause more problems than it would cure.

Al

Thanks Al,

The rotor on the GyroStick is bigger and heavier than the rotor on the MonoTwirl. Unless I switch to flexible flapping hinges (which I am considering) I think servo loads for the roll servo may be a concern.

The two bladed rotor I used was an experiment. I wanted to see if that design would be controllable as a sinlge rotor as I want to incorporate this into Cyclone. I think it is, although this is based on very limited testing. I could make the craft roll left or right based on how I ground adjusted the spindle side tilt.

Short daylight, bad weather, holidays....is any one else having trouble getting flying time?

Dan
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Old Dec 30, 2006, 09:13 AM
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Attached is a sketch I created recently for the Tempest (evolved from the Cyclone). It's just a basic layout but it helps me visualize things better. Note the flat inverted V and that the tailerons are all flying.

I still want to finish work on the HydroSkimmer and the GyroStick before I start building this since the work on these will have an impact on the Tempest design.


Dan
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Old Dec 30, 2006, 09:20 AM
Mickey from Orlando. Really.
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Quote:
Originally Posted by edi
I still didn't get why the right rudder induced a mast tilt to the left and therefore, left-cyclic pitch ...
In a typical model the mast is tilted aft.
If you view that model directly from behind the mast appears vertical.
Now if you apply rudder the whole model yaws nose right.
In the previous set of diagrams, the diagram with the ! shows the rear view of the model when it is yawed to the right. Because the mast is tilted aft, when that mast swings around with the tail (which swings left with right rudder) some of that aft tilt becomes left tilt. But the model is still progressing forward away from your viewpoint and the rotor has not moved. So the aft tilting mast being turned left has a left tilt to it.
In this diagram the whole model is shown after right rudder has been applied. It still is going directly away from you. Notice that the aft tilting mast has swung around and now leans left, relative to the direction you and the rotor are going. This is left tilt/left cyclic.
does this clear it up?
mick
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Old Dec 30, 2006, 09:38 AM
Mickey from Orlando. Really.
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Composite answer.
Dan,
The "v" in the linkage is likely to cause more problems than it solves. It introduces a spring into the control system that will likely allow a wobble to occur.
You've hit upon the basic problem with direct control, that is that the centrifigual and flight forces can feed back to the servos. It's easy to see how the tilting spindle gave way to the swashplate once you understand this.
Ari, I don't like V tails when you need lots of control. Full elevator and full rudder means only one surface moves. I think if you want roll control with out tilting the mast you should do differential elevators (ailevators, staberons, etc) and a conventional rudder. If you make the stabs all flying or with large percentage surfaces you will get adequate fuselage roll(and thus indirect cyclic) and elevator control (also we now know this is indirect cyclic and CG shift as well).
I think I'd try ailevators and rudder first, work out all the kinks then try V tail once you knew everything else works out. The problem with the V tail is once the angle is rigged you can't control the aileron to rudder coupling, so you don't have independent yaw control to keep the turns coordinated. Clearly from the above discussion, keeping the turns coordinated is a good idea. I think by experiment you could find a good compromise angle, but this is a ton of work compared to just throwing on another $10 servo and a pushrod. (I mean does any body still have a 3 channel transmitter and 3 channel receiver? I question the reduced cost and low complexity argument of 3 vs 4 channels. There must be some other attraction to 3 channels that I can't get a handle on.)
The easy way out is to stiffen the stab on a slow stick and split the elevator halves and just add another elevator servo and turn on mixing in the TX.
In a sense Al has outsmarted us all. By working with small models and depron he can control the flap of the blades easily and stay at a size where any servo is strong enough.Kudos Al.
nice to see a lively discussion.
When I get to it we will go into following rate and controllability. Then you'll have the whole picture of why a rudder, elevator, flapping hinge, coned, high following rate model is so technically difficult that no one really got one to fly well.
mick
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Old Dec 30, 2006, 09:57 AM
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For the GyroStick I'm stuck with 3ch for the time being. Another strategy I was thinking of was to mount a stronger servo to the rotor frame permanently. When I swap the rotor assembly for the fixed wing, I could plug this roll servo into the rudder servo output of the Rx via a splitter. Accept for the Y connector this leaves the basic frame stock and allows for my 3 ch limitation in both configurations (rotor, fixed wing).

Dan
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Old Dec 30, 2006, 10:04 AM
edi
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Thanks for the reply, Mick. I had forgotten about the mast tilt.
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Old Dec 30, 2006, 10:36 AM
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I think that Dan posted this link previously - there are a number of single rotor autogyro designs there, one of which seems to have a fixed 4 blade rotor and rudder/ailervator control.

Here is the link (in Japanese but it can be converted using Babelfish via the second link):-

http://rcp.web.infoseek.co.jp/rc2_O_Gyro.html

http://babelfish.altavista.com/babelfish/tr

Al
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