DO-24 and BV138 - Page 18 - RC Groups
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Jul 11, 2008, 08:33 PM
It's a Great Day to Fly
LenBFP's Avatar
Finally have the linkage done, only one of the two rudders actually work right now, but I figure with differential thrust that should be ok for a maiden. I need to get some more of the little control horns so I can couple the two rudders.

The controls have all been tested and adjusted, batteries are charged and it looks like the weather will be ok tomorrow morning, the camera operator is available, so ... here's hopeing.

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Jul 12, 2008, 04:22 AM
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Heat shrink joiners?

Hi Len,

Good luck with the maiden, I've been looking forward to this time.
For your lack of control horns, one solution would be to make a push/pull rod .
If you have thin carbon rod or a thin 2mm bamboo skwer, you can connect the two rudder trailing edges by means of small pieces of heat shrink, like the shocky guys use for their light weight set ups?
Cheers, regards to all, Al
Jul 12, 2008, 10:52 AM
It's a Great Day to Fly
LenBFP's Avatar
That is a great idea Al, I have actually used that technique on lightweight 3D models, but didn't even think of it.

Posted a couple of videos of attempts to get airbourne over in videos:

The right motor on the flaps channel is not developing full thrust but maybe enough. It was pretty windy by the time everything was turning in the right direction and all the motors were pulling in the same direction.

I am digging in a float and spinning around it, not quite sure what to do, maybe it will be easier to keep it out of the water if there is less chop and wind. Maybe I need to shorten the float mount or lengthen it so both are in the water. Any advice?

Last edited by LenBFP; Jul 12, 2008 at 11:04 AM.
Jul 12, 2008, 05:27 PM
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Side thrust? Adverse yaw? CofG correct?

Hi Len,
Good effort mate, these things are sent to try us, you, in this case.
I watched the vids briefly and it seems to turn more to the left, at the moment of rotation, imho, so a couple of reasons spring to mind.
1. You may need to be using the secondary effect of rudder to keep the wings level, or are you using the ailerons?
2. Do you have differential movement in the ailerons, ie. each aileron moves 2 to 3 times more upwards than downwards?
3. Motor torque from three motors without enough side thrust to the right may exacerbate the yaw to the left, especially as she comes on step and the fulcrum is the step behind the C of G. enough to think on for the moment.
How about a hand launch and see how she goes? Or wait for better weather, I don't think the wind is a problem, you will attain flying speed in less time. But the 'chop' might be the cause. Good luck with the fix, I guess you can study the original video in high quality and slow motion to get a better idea of what is going on? Cheers, regards to all, Al
Jul 12, 2008, 07:35 PM
G G Ghost Pirates !!!
Vyceroy's Avatar
Maybe use some counter rotating props.. switched my goose to them today and smooth as buttah off the water ..

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