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Old Mar 13, 2010, 09:26 PM
Build A Rocket Boys!
PDX Slope Pilot's Avatar
Portland, Oregon
Joined May 2002
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And to add to what Tom said, not only put the servo in the frame but make sure it's bolted in (I'm sure you meant that Tom but wanted to make sure it was clear!)

Vic
...who's made that mistake before
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Old Mar 13, 2010, 09:54 PM
Detail Freak
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Harbor City, CA
Joined Oct 2003
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Quote:
Originally Posted by tewatson View Post
Never put frames in without the servos installed. This is a guaranteed way to tweak the wing skins, regardless of how much carbon is in the layup.

Tom
I have never done it that way, nor would I ever, but it's mostly a thing of laziness for me.... Why do the extra work?

I DID figure out a new way to glue in servos in the frames. Instead of putting the servo in any type of barrier plastic as some guys do, I used a Q-tip and a little PVA on the Q-tip applied lightly to just the servo case, let it dry, and then glued it in, with the epoxy applied to the frame semi-generously. I'll not try to get the servos out unless needed, but they should be well potted and still come out easily with the PVA....

R,
Target
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Last edited by target; Mar 13, 2010 at 10:54 PM.
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Old Mar 13, 2010, 10:29 PM
Challenge is rewarding
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San Diego, CA
Joined Aug 2004
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I like the PVA trick
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Old Mar 13, 2010, 10:51 PM
Detail Freak
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Harbor City, CA
Joined Oct 2003
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10 different ways to skin a cat.....

Will it be windy tomorrow at the field you think??

Xplorer/Psyko, or
Xplorer/Tracer??

R,
T
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Old Mar 13, 2010, 10:52 PM
Build A Rocket Boys!
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Portland, Oregon
Joined May 2002
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Target/djklein21: What do you guys use to apply weight to the frames while they're curing? I've used a small block of lead (40mmx20mm) but wondering if that is too much weight.

Thxs,

Vic
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Old Mar 13, 2010, 10:53 PM
Challenge is rewarding
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San Diego, CA
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No, not really http://www.wunderground.com/cgi-bin/...weekday=Sunday
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Old Mar 13, 2010, 10:55 PM
Registered User
USA, CA, Aptos
Joined Jul 2005
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PVA tends to be a pretty crappy mold release on it's own. I would wax rather than PVA the servo case. PVA over the wax would be even better.
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Old Mar 13, 2010, 11:37 PM
In F3J size does matter!
roydor's Avatar
Israel
Joined Nov 2006
839 Posts
I use wax, I wax the servo well and from all sides before installing in the frames then glue them in the wing. I use a plywood frame for all my servos, cheap and glues well.
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Old Mar 14, 2010, 12:52 AM
RIP MC
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United States, CA, Midway City
Joined Dec 2003
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Getting 90 degrees of flap throw should be easy on the Xplorer. I can get 93 degrees.

The key is to adjust your TX to allow for maximum throws. Most servos I have tested will do 110-120 degrees of total travel. You can get a max of 95 degrees oneway ( 761, 3421, 368, 378), so that leaves at least 15 degrees for the other direction.

Now the horn on the flaps needs to have that clevis hole about 2mm in front (towards LE) of the hingline. The more the better actually. This is becasue when at full flap deflection, that horn becomes a 2mm "arm" as 2mm of that horn will be "above" the hingeline. Servos should only be canted toward LE about 5-10 degrees.

When full throw is given the the servo arm is or almost is "in-line" with control rod.

This will result in the least distortion of the top skin and the best mechanical connection when at full flap deflection. You can also wedge a piece of balsa in between servo/frame and wing spar for additional strength.

I can't find my drawing of the Xplorer flap detail, but here's one of Aspire which is basically same.

You can see the the control rod length is shorter at 90 degrees of throw in the picture. In this particular example, adjusting the horn out an additional ~1.5mm ( or going shorter servo arm) would be perfect for 90 degree flaps. On Xplorer, you would want longest flap horn possible and still give required throw.
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Old Mar 14, 2010, 01:14 AM
Sink Stinks
Silent-AV8R's Avatar
Orange County, CA
Joined Aug 2004
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Quote:
Originally Posted by target View Post
10 different ways to skin a cat.....

Will it be windy tomorrow at the field you think??

Xplorer/Psyko, or
Xplorer/Tracer??

R,
T
Wow, I wish I had those choices and was able to make that kind of decision. I'm stuck with my 3.8 Xplorer. If it's windy I can add ballast I guess.

See Ya'
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Old Mar 14, 2010, 01:17 AM
Sink Stinks
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Orange County, CA
Joined Aug 2004
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Quote:
Originally Posted by fnnwizard View Post
Getting 90 degrees of flap throw should be easy on the Xplorer. I can get 93 degrees.
Good to know. But at 75 degrees I can stop mine cold in the air so I'll have to suffer through without that extra 18 degrees. I already land short too often as it is. Good thing I don't have that extra flap travel, I'd probably never get off the winch line!!
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Old Mar 14, 2010, 01:20 AM
Sink Stinks
Silent-AV8R's Avatar
Orange County, CA
Joined Aug 2004
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Quote:
Originally Posted by PDX Slope Pilot View Post
Target/djklein21: What do you guys use to apply weight to the frames while they're curing? I've used a small block of lead (40mmx20mm) but wondering if that is too much weight.

Thxs,

Vic
I am not either Target or David, but I use a small paper cup with a few ounce of lead shot in it. Just enough to keep pressure. Maybe 3 or 4 ounces of shot?? I also do as Tom Watson does and NEVER glue frames unless the servo is in them. I use Saran wrap on the servo to keep it from getting glued in.

I'm still sort of finding my way, but so far that method has worked for me.
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Old Mar 14, 2010, 07:48 AM
Detail Freak
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Harbor City, CA
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Quote:
Originally Posted by Silent-AV8R View Post
I am not either Target or David,
Lucky!

R,
Target
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Old Mar 14, 2010, 10:54 AM
Win=span\massXpractice+lu ck
webbsolution's Avatar
Joined Jul 2007
2,964 Posts
Quote:
Originally Posted by ak79 View Post
I tacked the frames in with thin CA, then went back over them with some thickened resin. After is was dry I put the servos in and hooked up the linkage, moved the flaps a bit, and wammo, some dents showed up! Oh well. I guess I shouldn't let it bother me to much, I am a bit picky.

Right now i am using some bass wood to try and tie the top and bottom skins together around the servo to try and keep this from getting worse.
I made that mistake wiht a pike perfect... no CA on those skins it sucks the skin down when it cures everytime.

Slow cure (12 hour) epoxy and some light weight to keep it in place is a better idea.
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Old Mar 14, 2010, 10:57 AM
Win=span\massXpractice+lu ck
webbsolution's Avatar
Joined Jul 2007
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Quote:
Originally Posted by PDX Slope Pilot View Post
And to add to what Tom said, not only put the servo in the frame but make sure it's bolted in (I'm sure you meant that Tom but wanted to make sure it was clear!)

Vic
...who's made that mistake before
NOT yet lol but I did fly an entire contest with a servo arm that was not screwed into the servo...at least I know the push rod was totally square!
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