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Old Feb 24, 2012, 11:47 AM
Detail Freak
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Harbor City, CA
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Quote:
Originally Posted by giammi77 View Post
Very good work !!
++1, Roy!

Thanks for documenting the process with pictures also. I know how much this normally slows the procedure.

Thank you.

R,
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Old Feb 24, 2012, 01:34 PM
chetosmachine's Avatar
Madrid, Spain
Joined Sep 2004
1,102 Posts
Excellent work there!
I'm sourprised you had troubles working with the textreme. Which carbon did you use? Does it have some kind of binder?
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Old Feb 24, 2012, 03:19 PM
Thermal Wrangler
DrFragnasty's Avatar
Launceston Tasmania
Joined Mar 2004
2,117 Posts
Measuring spar depth

Looks great Roy, thanks for posting.

How did you determine the depth to cut the main spar? I'm guessing bits of putty at points along the wing, close the mold, squash the putty, remove wing-half, measure heights, subtract 1mm for the bog mix?


Chris.
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Old Feb 24, 2012, 03:31 PM
In F3J size does matter!
roydor's Avatar
Israel
Joined Nov 2006
851 Posts
The fabric kept trying to roll back to the shape it had when packaged. In addition the UD tows became disorganized at some places and gaps formed between them. When cutting the fabric the edges wanted to break apart. I used a thin sheet of nylon film and used 3M adhesive to stick it to the spread tow and then it became real easy to handle the fabric, cut it accurately and place it in the mold. After placing it in the mold the I removed the nylon film but had to find a way to remove it without messing the edges when pulling it out. In the end I managed doing it well but it takes more time in comparison to "regular" carbon. Great mechanical properties but requires special care which wasn't required in the past.
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Old Feb 24, 2012, 03:54 PM
In F3J size does matter!
roydor's Avatar
Israel
Joined Nov 2006
851 Posts
DrFragnasty,

I calculated the height of the web at 20 cm intervals from the airfoils and laminate thickness and made small blocks 1 mm lower. I put tape on the spars to prevent them from getting dirty and then I put polyester putty on the blocks, top and bottom, and placed them at 20 cm intervals and closed the molds. 15 minutes later I had myself small posts of hard material showing me the local thickness and I could measure it accurately using a caliper. I sanded my webs to 0.5 mm of that measurement and as always, I ended putting just a little bit more epoxy to make sure I had a good bond. If I had to guess I would say I have no more than 10 to 15 grams of extra epoxy per panel for safety reasons.

Roy
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Old Feb 24, 2012, 04:00 PM
In F3J size does matter!
roydor's Avatar
Israel
Joined Nov 2006
851 Posts
Quote:
Originally Posted by target View Post
Thanks for documenting the process with pictures also. I know how much this normally slows the procedure.
I actually feel a little ashamed, I planned to take much more pictures then I ended up taking but got lazy. Also, I took many pictures with my cell phone camera because I forgot my good camera at home. The previous Gremlins were more documented and I initially planned to do more then I ended up doing.
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Old Feb 24, 2012, 05:14 PM
Detail Freak
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Harbor City, CA
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Well, I'm happy for any pictures that get posted of build techniques....

Thanks again.

R,
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Old Feb 24, 2012, 05:20 PM
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Norway
Joined Dec 2003
1,454 Posts
Thanks for the updates. Watching closely
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Old Feb 26, 2012, 04:00 PM
Registered User
Sydney
Joined Apr 2009
716 Posts
Thanks for the photos and info Roy. Really nice work.
John
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Old Mar 03, 2012, 10:44 AM
In F3J size does matter!
roydor's Avatar
Israel
Joined Nov 2006
851 Posts
I had some time today so I opened the servo bays in the wing.
I'm REALY happy with what I saw. The web is glued to the spar cap very cleanly, no blobs of epoxy and no voids in all four bays. Obviously I can't see the entire web and the aft web obstructs the view of the front one but since the web on all four bays looks good, I feel it's a good representation for the rest of the wing. I've attached pictures of the webs from all four bays which aren't very good (the pics) as they make the leftovers look more then they actually are with some voids which in reality aren't there, it's just full to the right extent.
The carbon socks seem to have come out nicely as well and the epoxy soaked sponge is nice and rigid. It can be crushed with some pressure but that kind of pressure doesn't exist in that area anyways and it took no time at all to do.
The servo bays themselves came out rigid and I couldn't see skin flex when I pressed on them from the outside.
Also, the wing looks plenty stiff and has a good chance of being an all weather model. First flights will show if this is true or not

BTW, after finishing the trimming of the leading and trailing edges and opening the servo bays the weight of the left wing is 542.3 grams and the right wing is 541.3 grams
I'm going to wait with opening of the flaps and ailerons until I complete the pod and check the alignment of the wings relative to one another, it's simply easier before cutting them as I can measure the angle more easily with a stiff wing (no flapping surfaces).

I've ordered servos for the wing. Going with 761's for the flaps and 809's for the ailerons. From what I've heard so far the 809's should be sufficient even for strong launches in windy conditions.

This week I hope to get the molds of the rudder and pod ready for molding and to prepare the materials for them. I want to mold them both on the same day so to save the setup and cleaning time involved in the molding process.

Roy
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Old Mar 03, 2012, 10:56 AM
Detail Freak
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Harbor City, CA
Joined Oct 2003
21,680 Posts
That DOES look like a great bond to the skins. Thats as good or better than I've seen in any production molded plane.
Good job and congrats!

The 11mm servos (Airt 809, Hyperion DS11) have been nothing but stellar for me. I have them in all the aileron positions of my TD planes, including the 4M Xplorer.
They are great for F3B and F3F v-tails also.
I like the Hyperion DS11 a little better for the v-tails; they are available in resin/carbonite gears, so zero slop.

R,
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Old Mar 05, 2012, 09:09 AM
In F3J size does matter!
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Israel
Joined Nov 2006
851 Posts
I decided to go ahead and open the ailerons and flaps as I thought of a way to check their alignment to the fuselage regardless of them being cut. On this model I decided to make the flaps and ailerons the entire span of the wing.
I hate not having a fixed reference to their alignment when flying in order to check for thermal drift (servo) and bent pushrods, but it ends up slightly lighter and more aerodynamically efficient so I decided to give it a go.
After opening the moving surfaces I found excellent bonds on all and super stiff surfaces due to the carbon tubes and spread tow combo. This wing is VERY strong in torsion and if the spar system ends up as strong, I'm expecting an all weather model for sure!

I'm extremely happy with the results so far
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Old Mar 05, 2012, 09:19 AM
Detail Freak
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Harbor City, CA
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Looks great!

R,
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Old Mar 07, 2012, 03:11 PM
In F3J size does matter!
roydor's Avatar
Israel
Joined Nov 2006
851 Posts
I molded the flaps gap seal. Made it out of epoxy and micro-balloons using tape as a guide for the shape. For the ailerons I plan on using tape to save some weight.
I also installed the locating pins at the root, two stainless steel pins 4 mm in diameter per wing panel.
The weight of the wing panels is now 549.5 grams and 549.9 grams

Next step will be to install brass horns for the ailerons and flaps.
After that install the servos and solder and install the wing harness and the wing will be finished.
I haven't decided which color servo covers I'll use, I have carbon servo covers and I have red covers I made a year ago. I might make yellow ones to blend in with the wing next time I paint something (fuse or ruder), we'll see...
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Old Mar 07, 2012, 04:16 PM
Detail Freak
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Harbor City, CA
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Its going to fly much better with the red covers!

R,
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