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Old Dec 20, 2014, 09:24 PM
Soarrich
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Middletown, NJ
Joined Dec 2003
527 Posts
Help!
I don't know what is wrong with my gyro, do you?

Cat in hat RC gyro. (0 min 41 sec)

The first attempt it was windy, when gave it up the gyro came up, but it looked too steep so I gave a little down and it dove into the ground.

Cat in hat second attempt at flight. (0 min 35 sec)

Almost no wind on second attempt. I cut some of the "Elevator" throw and added some nose weight so it would hand about 10 nose down. I also added some more back angle on the rotor's normal setting, but it still would not lift off without pulling back.

Any suggestions?
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Old Dec 21, 2014, 12:43 AM
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Jockadopolus's Avatar
Scotland
Joined Jan 2010
1,111 Posts
Rich you are so close to getting it flying
What are the head and blades from?
Posting video of test flight problems is very helpful to see what went wrong

A couple of things I would check
1.Hang angle a bit more than 10deg
2.Check the neg pitch on the blades too much and you will lose lift
3.The main wheels look a bit too far back and may not allow the model to rotate

Keep videoing any more flights, I rely on videos for my tests as I can never remember exactly what my model did
Joe
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Old Dec 21, 2014, 01:26 AM
Soarrich
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Middletown, NJ
Joined Dec 2003
527 Posts
Quote:
Originally Posted by Jockadopolus View Post
Rich you are so close to getting it flying
What are the head and blades from?
Posting video of test flight problems is very helpful to see what went wrong

A couple of things I would check
1.Hang angle a bit more than 10deg
2.Check the neg pitch on the blades too much and you will lose lift
3.The main wheels look a bit too far back and may not allow the model to rotate

Keep videoing any more flights, I rely on videos for my tests as I can never remember exactly what my model did
Joe
Joe
1.The hang angle is about 10.
2. I'm thinking this may be the problem. I'm using Flying Balsa's rotor and blades so I never actually check the negative pitch, I assumed it would just be correct. I find the blades spin up very easily, so they maybe too negative pitched.
3. I don't think that's the problem, it seemed as though it over rotated on the last attempt, that's what caused the dump.
I try to get my wife to video for me, but it's tough to get her out there. I've tried guys, you get a lot of sky and grass, aircraft not so much.
The last flight broke the hinge on one blade, it was below freezing, so now I have to disassemble the head and make a new hinge.
Rich
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Old Dec 21, 2014, 02:17 AM
What could possibly go wrong!!
In Bedfordshire, UK.
Joined Oct 2008
679 Posts
Rich

That was so close and I think as Joe said it is likely to be hang angle, if possible aim to get it nearer say 14deg but without adding weight. You might also try a few hops first to get the feel of it but keeping the lift off point as close to you as possible to avoid disorientation.
Good luck but dont give up, you are nearly there.
Chas
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Old Dec 21, 2014, 09:52 AM
It was a GLITCH! Honestly!
SafeLandings's Avatar
Stourport on Severn ,Worcestershire, United Kingdom
Joined Dec 2007
4,930 Posts
Rich,
Looks to me that you have too much negative incidence added to your blades, they looked to spin up really quickly with no lift off until you pulled back on the rotors. What you need is the least amount possible, this way you will get the best lift from the blades.
If your thrust line is above the CG position this will cause the nose to dip under power, the more lift/drag your blades produce the lesser this effect.
Also, if you are able to adjust your U/C so that the horizontal stab is parallel well with the ground this will help ROG. To me it looks like its pointing down slightly?

Keep at it mate.

Rich
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Old Dec 21, 2014, 09:54 AM
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New Jersey, USA
Joined May 2003
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You have good head speed. What I see is not enough, or not enough available, left rudder input to level the airframe. With a high angle at lift-off, cyclic roll/tilt, isn't always enough to catch the right roll. I suggest a larger rudder.
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Old Dec 21, 2014, 02:01 PM
It was a GLITCH! Honestly!
SafeLandings's Avatar
Stourport on Severn ,Worcestershire, United Kingdom
Joined Dec 2007
4,930 Posts
Way to much negative incidence Rich, look at getting around 1 degree maximum, try and get a bigger hang as well at around 15 degrees. With three blades the rotor should be about 5-6 degrees off horizontal tipping rearwards. The reason why it is tipped back so much is because of the excess negative shim on the blades.

Rich
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Old Dec 21, 2014, 05:56 PM
Mickey from Orlando. Really.
Joined Nov 2004
3,677 Posts
What's the disk area and weight?
Plenty of rotor speed, looks like it might be too heavy.
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Old Dec 21, 2014, 08:41 PM
Soarrich
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Middletown, NJ
Joined Dec 2003
527 Posts
Disk area is 2200 sq. in., I never weighted it, but probably about 5~6 pounds. I'm going to take -3 negative out of the blades and try again.
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Old Dec 22, 2014, 08:30 AM
Mickey from Orlando. Really.
Joined Nov 2004
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Quote:
Originally Posted by soarrich View Post
Disk area is 2200 sq. in., I never weighted it, but probably about 5~6 pounds. I'm going to take -3 negative out of the blades and try again.
This is almost 7 ounce per square foot disk loading. The issue may be not enough power/speed. About 5 ounces/ft^2 is a good number to start with for small models, less is better. Properly loaded it should lift off by itself.
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Old Dec 22, 2014, 09:39 PM
Soarrich
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Middletown, NJ
Joined Dec 2003
527 Posts
I just weight it..........7.8 pounds we'll wait after the next attempt to see if a diet is in order, so far the filling of the aluminum channels with wood has kept it from bending like a pretzel.
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Old Dec 22, 2014, 09:42 PM
Soarrich
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Middletown, NJ
Joined Dec 2003
527 Posts
Quote:
Originally Posted by SafeLandings View Post
Way to much negative incidence Rich, look at getting around 1 degree maximum, try and get a bigger hang as well at around 15 degrees. With three blades the rotor should be about 5-6 degrees off horizontal tipping rearwards. The reason why it is tipped back so much is because of the excess negative shim on the blades.

Rich
Ok, I'll use your numbers on my next attempt. Thanks.
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Old Dec 22, 2014, 09:45 PM
Soarrich
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Middletown, NJ
Joined Dec 2003
527 Posts
Do I need the stab? I put it on mainly for visibility, is it needed aerodynamically?
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Old Dec 23, 2014, 07:36 AM
Mickey from Orlando. Really.
Joined Nov 2004
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Quote:
Originally Posted by soarrich View Post
I just weight it..........7.8 pounds we'll wait after the next attempt to see if a diet is in order, so far the filling of the aluminum channels with wood has kept it from bending like a pretzel.
8 ounce/ft^2 loading is probably your problem. You need to lose 3 pounds somewhere or make a much bigger rotor. Shoot for 5 ounces/ft^2.
At 8 pounds you probably need 3-4 pounds of thrust, 600 watts probably.
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