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Sep 28, 2021, 01:34 PM
Always trying to learn
mejmea's Avatar
Thanks for posting these discoveries Werner - very helpful!
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Sep 30, 2021, 11:33 AM
Registered User
Hi all

I tried to drive on the ground, the whole thing seems so weird to me, it doesn't turn out well. The model does not try to detach from the ground, it seems very heavy on my nose. Eventually, the rotor destroyed the end of the elevator, after removing the rotor blades, I discovered this. What do you think about it? See photo (it's cracked)
Sep 30, 2021, 01:14 PM
Registered User
Thread OP
😯 did the model tip over or is this damage just from driving around and the tail strike?
I did kill two delta plates but these were at hard landing/crash's and effected only one arm not all three at once.
This and the damage of the elevator indicates that the rotor did not have proper speed. Did you test on a completely calm day or did you have some wind? If the rotor does not reach sufficient speed, you drive circles (including crosswind passages) and probably have gusty wind, all this may result in excessive blade flapping, often resulting in a tail strike. I repaired one just yesterday.
Choose a day with a steady turbulence free wind. Point the nose of the model in the wind. Give the rotor a generous pre-spin with your hand. Wait! The rotor should spin up further. If it does, pull the elevator slightly. The rotor should spin up faster. Pull the elevators full, but only if rotor already has good speed. Rotor speed might still increase a bit. Release Elevator to neutral and start the motor to move forward slowly. Rotor at least keeps speed or increases. Increase gas, to move forward and model should take off at about jogging speed. If rotor does not speed up at slow forward speed, abort start. Cut motor, push elevator full down. Wait. Stopp rotor by hand. Then find reason why no rotor speed. I know, this is the big question, sorry.
If you just want to test choose a day with a bit more wind, just to test run up of the rotor. Danger here is, that the model might choose to take of while you do not expect it to, often resulting in a tip over, including possible damage.
Sep 30, 2021, 02:29 PM
Registered User
Hi Werner thanks for the reply
Wind light breeze, I rode the model in circles, the rotor gained speed, I decided to start, the gradual addition of gas, the whistling of the rotor accelerated, the model raised its tail about 40m from me and drove only on the ground, at 70m I interrupted the start to make it he slowed down, so I pulled on the elevator and stopped after a while, everything ok.
Then I tried to drive on the ground again and the rotor blade tripped over the raised part of the elevator, so it was not worth continuing the test, when I removed the rotor blades, I noticed that the plate was damaged.
The model is undamaged, did not overturn, did not fly, the rotor blades did not hit anything, only the raised part of the elevator was lowered.
Could this have happened during that interrupted start when I pulled on the elevator and the model landed on the spur wheel? There is not much to see at a distance of 70m.
The model weighs 3.2 kg, the suspension angle is 16-16.5 degrees, it seemed to me at the start that it did not want to detach from the ground, because it is heavy on the nose.
Oct 10, 2021, 12:13 PM
Registered User
I'm still waiting for the weather, I need a light south wind to make the first turn to the left. I already know where there could be a mistake that the model did not want to air.
Oct 10, 2021, 12:32 PM
Always trying to learn
mejmea's Avatar
Quote:
Originally Posted by michal39
I'm still waiting for the weather, I need a light south wind to make the first turn to the left. I already know where there could be a mistake that the model did not want to air.
What do you think the issue was?
Oct 10, 2021, 01:32 PM
Registered User
I think the mistake was not in the model, but in me. I'll find out more when I try the model again.
Oct 10, 2021, 01:54 PM
Always trying to learn
mejmea's Avatar
Quote:
Originally Posted by michal39
I think the mistake was not in the model, but in me. I'll find out more when I try the model again.
Ha, that's where most of my mistakes are!
Oct 20, 2021, 01:28 PM
Registered User
Hi Werner

Would you be able to measure the tilt of the rotor blades as in the photos? It would help me a lot. I've measured 1.3, 1.4 and 1.6 degrees and it seems small to me. The small Cierva model has 2.0 degrees
Oct 20, 2021, 02:11 PM
Registered User
Thread OP
According to my measurements with a smartphone clinometer app I come to 1,7degrees +-0.05 to 0.1.
You may also remeasure in Fotos in #219.
Oct 21, 2021, 08:35 AM
Registered User
Thanks for the reply, I didn't notice that it was already being addressed here. My rotor blades have a smaller inclination, I decided to make it 2.0 degrees, the rotor should theoretically spin faster.
Nov 05, 2021, 09:56 AM
Keep it simple
alfoot's Avatar
Hi all,

I had another go with my C30 on 3 November. I had recently noticed significant slop in the rotor bearings, which allowed to rotor head to "set" up to half a degree relative to the mast, in any random direction. By which I mean that I could apply a force to the head and could feel a click as it changed angle. Maybe this contributed to my previous issues. With the new bearings installed I could not make the rotor head move in this way at all.

I changed the propeller from a 16 x 8 to a 14 x 8 to hopefully reduce any motor torque effects

I did a few ground rolls, increasing speed to get the rotor chirping, and got the wheels just off the ground to assess lateral trim. At the end of these hops I was ready to go but the light was worsening.

Anyway, it tracked straight got airborne without drama. I was very cautious with application of bank angle, too cautious I think because it got too far away for me to orient properly. The result was a wrong roll input about 40 secs after lift-off which made it hit the ground and do a fair bit of damage. This was pure operator error.

The good news is that I felt like it was flying as it should, looking very similar to Werner's wonderful flights.

I have made contact with Astik Models for some new parts for the nose area, I await a response.

I will fix it and try again.

Here are a couple of stills from Bob's brief movie, I didn't think it was worth posting it but will if folks feel they would get anything useful out of it.

Al
Last edited by alfoot; Nov 05, 2021 at 10:13 AM.
Nov 05, 2021, 10:32 AM
Always trying to learn
mejmea's Avatar
Quote:
Originally Posted by alfoot
Hi all,

I had another go with my C30 on 3 November. I had recently noticed significant slop in the rotor bearings, which allowed to rotor head to "set" up to half a degree relative to the mast, in any random direction. By which I mean that I could apply a force to the head and could feel a click as it changed angle. Maybe this contributed to my previous issues. With the new bearings installed I could not make the rotor head move in this way at all.

I changed the propeller from a 16 x 8 to a 14 x 8 to hopefully reduce any motor torque effects

I did a few ground rolls, increasing speed to get the rotor chirping, and got the wheels just off the ground to assess lateral trim. At the end of these hops I was ready to go but the light was worsening.

Anyway, it tracked straight got airborne without drama. I was very cautious with application of bank angle, too cautious I think because it got too far away for me to orient properly. The result was a wrong roll input about 40 secs after lift-off which made it hit the ground and do a fair bit of damage. This was pure operator error.

The good news is that I felt like it was flying as it should, looking very similar to Werner's wonderful flights.

I have made contact with Astik Models for some new parts for the nose area, I await a response.

I will fix it and try again.

Here are a couple of stills from Bob's brief movie, I didn't think it was worth posting it but will if folks feel they would get anything useful out of it.

Al
Looks beautiful Al! I'm sorry to hear of the new damage but happy that you may have found the issue.

FWIW, my brother had a similar issue with his Hobbyking G2. It wasn't the bearing itself but rather a different part of the head, but it allowed the same kind of random/uncommanded motion of the rotor disk and it made it very squirrely to fly.

I'm always up for watching AG video so my vote is post it!
Nov 05, 2021, 11:42 AM
Registered User
Thread OP
I have very mixed feelings. I could jump from joy reading you fixed a problem and got airborne nicely and so sad for you new damage. I commend you for your perseverance. You could go to Mars . The day will come when you cruise around majestically with you C30.
Rule to note: never fly in bad light conditions. And this might even be a bright day with the model between you and the sun!


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