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Old Jul 14, 2008, 03:07 PM
Throw a glider!
glider90's Avatar
Columbus Ohio
Joined Mar 2007
401 Posts
Mulligan,
I have a pretty hefty supply thanks to years of hunting and hoarding. I have two very nice sheets of 3/8" C-grain that are right at 6 lbs. I was going to plane them down to 5/16" for a F/F DLG, but I think they just got earmarked for this project! The plans call for a sub 100 gram sheet that is 1000mm x 100mm x 10mm, which is 6.23lb/cu'.

I have purchased some 5/16" recently from Specialized Balsa and have always gotten what I asked for:
http://www.specializedbalsa.com/balsa_sheets.php
I asked for the lightest 5/16" he had in C-grain. I expected 6-7 lb, I got 5 beautiful sheets of sub 5 lb C-grain!

He does charge extra to select grain and density, but at least I get something I can use, not 5 sheets of template material. When he does not have what I want, he tells me. When he does, I usually buy him out!

Frans,
I received the plan, thank you, it is great.
Two questions.
1) what servos did you use?
2) I see three joints in the wing, but it appears to be a flat V dihedral, not a poly? What is the reasoning for the four section wing?

Thanks,
~Jim
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Old Jul 14, 2008, 03:33 PM
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Frans Bal's Avatar
Vlaardingen, The Netherlands
Joined Feb 2004
613 Posts
Jim,

I used Dymond d37 eco. But any (cheap) micro 4-5 gram servo will do.
Cheap servo

much much better but a bit more $

Alternative to the D47, but slightly bigger


Correct, the wing has a single dihedral.
The reason for four sections is ease of build.
The inner sections have AG03 --> AG03
The outer sections have AG 03 --> AG11.
So no complicated sanding required.
Only the tip needs a bit of accurate sanding.

Frans
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Last edited by Frans Bal; Jul 15, 2008 at 01:55 PM. Reason: Added servo HS45
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Old Jul 14, 2008, 03:37 PM
Registered User
Corona, CA
Joined Sep 2007
923 Posts
Thanks for the link, Jim.

Frans, I'm interested in the use of the sanding template. Are they simply glued temporarily to the ends of the plank, then just sanded with a long sanding block?

I have been playing with the idea of adding a third servo to give me camber and air brake. On my homemade all-wood Apogee, I found that it flies best with about 10 grams of ballast, even in still air. I thought, why not put that extra weight in the form of something useful?

I think, with the fast roll rates of small planes like this, ailerons would be overkill. However, they might benefit from the ability to change camber, and a brake to slow down for hand catching. The hinge line could be almost zero gap, since they would move only in the down direction. I don't know if the AG03 would benefit from a tiny bit of reflex, but I could add very small hinge gap to see if it does.

As soon as I finish by 60" ship, I'll start on this one.
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Old Jul 14, 2008, 03:49 PM
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Frans Bal's Avatar
Vlaardingen, The Netherlands
Joined Feb 2004
613 Posts
Yes, Just glue the sanding templates with some drops of CA to the ends of the plank and sand the airfoil with a long sanding block.
After sanding just "break" the template from the wing sections.

Frans
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Old Jul 14, 2008, 03:52 PM
Throw a glider!
glider90's Avatar
Columbus Ohio
Joined Mar 2007
401 Posts
Aha, I understand Frans.
Interesting approach that I am sure works quite well.

Thanks as well for the servo info, I just upgraded my Apogee to D-47's after a Bluebird BMS-303 went bad on me. THe Dymonds are very nice.
~Jim
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Old Jul 14, 2008, 03:56 PM
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Corona, CA
Joined Sep 2007
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Quote:
Originally Posted by glider90
Aha, I understand Frans.
Interesting approach that I am sure works quite well.

Thanks as well for the servo info, I just upgraded my Apogee to D-47's after a Bluebird BMS-303 went bad on me. THe Dymonds are very nice.
~Jim
I had a BMS 303 go bad this weekend, as well. Glitching over 90+ degrees, and staying there.
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Old Jul 14, 2008, 06:05 PM
Throw a glider!
glider90's Avatar
Columbus Ohio
Joined Mar 2007
401 Posts
Wow, EXACTLY the same failure I had!
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Old Jul 14, 2008, 06:19 PM
Registered User
Corona, CA
Joined Sep 2007
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Quote:
Originally Posted by glider90
Wow, EXACTLY the same failure I had!
I posted this issue on the Electric Plane Talk board, and apparently it can happen when the case opens up a bit, causing the pot to make poor contact. I can get the servo to function again, if I squeeze the case very hard between my fingers, from top to bottom, but as soon as I ease up the pressue, the same problem occurs, though very little noticeable gap has opened up on the case joints.

If you bought them from BP Hobbies, you can probably get a replacement:

http://www.bphobbies.com/view.asp?id=A1550136

I bought mine somewhere else, so I'm SOL...
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Old Jul 15, 2008, 01:53 PM
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Corona, CA
Joined Sep 2007
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Frans, what is your opinion on the D37 servos? The price dropped 50% on them recently. I did a quick search here, the feedback is mostly negative...
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Old Jul 15, 2008, 01:58 PM
Flying IS the hobby
Upstate, NY
Joined Feb 2002
2,110 Posts
Guys, the 303 are more delicate due to the size and weight, so unlike larger/heavier servos you can't force the gears in any way, ether by hand when the servo is off or 'hard landing' ... if you believe your servo was damaged when you got it, then contact BPH, as Mr._Mulligan suggested, they should be able to replace it

http://www.bphobbies.com/view.asp?id=A1550136

There is a compromise between weight and durability


--------------------------------------------------------------------------
I will be unsubscribing from this thread, so if anyone has direct questions or comments let me know...
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Last edited by jeb; Jul 15, 2008 at 02:35 PM.
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Old Jul 15, 2008, 02:12 PM
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Frans Bal's Avatar
Vlaardingen, The Netherlands
Joined Feb 2004
613 Posts
In holland we have a saying that goes something like this, You get what you pay for.
And that's the case with cheap servo's to.
The d37 Eco (i have a feeling it's the same servo that Bidproduct sells) does the job but don't expect a top one.
The resolution and centering isn't as good as a D47 (and that's saying it politely)
D47 have there own glitches, i have seen one go up in smoke for no reason and they seem to have a small temperature drift. I am using them in a Super Gee II Super Shot variant and they have some play on the gear, but nothing alarming.
A friend bought some Hirec HS-45 and they have a tight gear.
They are a bit noisy but when your at 300 feet........

Frans
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Old Jul 15, 2008, 02:27 PM
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Corona, CA
Joined Sep 2007
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Thanks for the input, Frans. The D37 looks very similar to this, although the reported torque is different.

http://www.hobbycity.com/hobbycity/s.../_.09sec_/3.7g

I'm hoping that the HS35 will be good when it comes out.
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Old Jul 15, 2008, 07:57 PM
Throw a glider!
glider90's Avatar
Columbus Ohio
Joined Mar 2007
401 Posts
Is the HS35 EVER coming out? I waited for a year and finally gave up. I thought they shelved the project?
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Old Jul 15, 2008, 09:20 PM
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Corona, CA
Joined Sep 2007
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I don't know. Hobby Horse keeps saying that it's "comming soon."

http://hobbyhorse.com/hitec_hs35hd.shtml

Maybe we've reached a temporarily limits to how small servos can go with the current technology. Most sub-4g servos are not very reliable in my opinion.
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Old Jul 17, 2008, 01:12 AM
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Corona, CA
Joined Sep 2007
923 Posts
Well, it looks like HS-35 may never be...

http://www.rcgroups.com/forums/showthread.php?t=802237
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