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Old May 18, 2015, 12:51 PM
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It's a spiderweb of knit lines
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FF EDF Panther

Used some foam from the micro rc Panther I designed and made this:
30 grams AUW
16" wing span
TP 160mah 1s
mSR X coreless motor
GWS fan and shroud
Home made timer

Flies well but I can't seem to get it to turn in the glide. Circles up nicely but then heads straight for the trees when gliding.
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Old May 18, 2015, 01:20 PM
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From that one picture it looks like there is little or no dihedral. Any rudder offset you use gives the model some yaw. But that yaw angle needs to work with some dihedral to produce a roll up into a turn.

And with so little or no dihedral I'm actually a little surprised that it's stable in the climb and glide. I'm guessing that the large amount of side area and fin area above the true CG of the model is giving it a little bit of stability from the keel like effect.
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Old May 18, 2015, 02:06 PM
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It's a spiderweb of knit lines
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Here's a pic of the dihedral. It has more than enough.
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Old May 18, 2015, 05:38 PM
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Yep, that should do it alright.

How much rudder tab are you using? You may need to force it to fly in circles in the glide than adjust the thrust to make it turn the same diameter circle under power.
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Old May 18, 2015, 07:03 PM
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A bit more dihedral would help.
Tip weight for the glide circle is probably your best bet.
It does look wonderful though.
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Old May 18, 2015, 09:51 PM
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Another thing is that the picture shows quite a strong curve in the fuselage that would be trying to promote a right turn. You should go with that option and make the curve work for you if you are not doing so already.
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Old May 18, 2015, 10:11 PM
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It's a spiderweb of knit lines
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I don't think it needs more dihedral, it's very stabile in roll.

I have two rudder tabs. One is the actual rudder that gets some but not much jet wash, the other is the lower fuse in the jet wash. Next time out I'll try the wing weight, if that doesn't work I'll trim for a turning glide and adjust thrust for the climb.

I have say I'm loving this electric ff. I just follow the plane around the field with a 9 volt battery in my pocket. No more walking back to wind, no more stooge or winder to drag to the field. Just the plane a couple flight batteries and the 9 volt starter battery.

Thanks!
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Old May 19, 2015, 07:18 AM
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and schematics on how you make the timer I am starting to play with capacitor but would like to try lithium polymers with a timer.
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Old May 19, 2015, 09:10 AM
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Timer was designed by Bob Kopski, I'll ask him if I can post info. It's very basic, no bells or whistles. It consists of a cap, fet, resistor, pot and a switch.
There are better ones that use micro controllers and have battery protection.
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Old May 19, 2015, 11:44 AM
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Quote:
Originally Posted by funwithplanes View Post
and schematics on how you make the timer I am starting to play with capacitor but would like to try lithium polymers with a timer.
Quote:
Originally Posted by mcross View Post
Timer was designed by Bob Kopski, I'll ask him if I can post info. It's very basic, no bells or whistles. It consists of a cap, fet, resistor, pot and a switch.
There are better ones that use micro controllers and have battery protection.
The simple timer like Bob came up with is only good for brushed motors. I made up a couple and also presented a writeup on how to make your own easily a bunch of years ago. It's the same circuit used by a bunch of folks on the web but I added the parts and layout diagram shown for making it up on a small bit of prototyping strip board.

http://www.rcgroups.com/forums/showp...2&postcount=12

Of course this simple approach is sadly only good for brushed motors. For brushless we can't do it this way and a snazzy microprocessor controller is needed.

Back to the model trim. You likely need to fit a small power tab in the exhaust blast as an option for actually angling the EDF unit. The rudder that sits up on the fin can then be used for the actual glide adjustments with no thought of the power run. Then the power tab in the exhaust is adjusted to aid or fight the rudder adjustment.

I've always found that if the tab is too small I only get some control up to a fairly slight effect then nothing much at all after that without gross angles being used. As a result I gave up on small partial tabs many years ago. Instead I warp or adjust the whole trailing edge of the fin so the adjustment acts like a full rudder. If you're trying to use small tabs this could be the issue.

It's tough trying to diagnose issues like this over the web. Sorry if I might be offering hints that are well known already but when there's likely something on the model that is fighting the turn it's a bit like trying to get around with blinders on.
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Old May 19, 2015, 10:05 PM
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Bruce's timer is pretty much the same as the one I'm using except I don't have a diode, I have a mechanical polarity protector.

I appreciate the help Bruce and you don't need to be sorry about offering any well known hints. It wouldn't be the first time I overlooked something I shouldn't have.

Weather here's going to be windy until Thursday or Friday. I'll try to get video next time I take her out.
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Old May 21, 2015, 10:00 PM
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It's a spiderweb of knit lines
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Flew it a few times tonight and it's turning a little in the glide. I even caught it a few times when I launched crosswind. Still needs some more trimming, I want a tighter turn in the glide. Couldn't get video, I can't find my charge cable. Next time I'll get video.
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