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Old Nov 02, 2012, 04:54 AM
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Tuomo's Avatar
Jyvaskyla, Finland
Joined Aug 2003
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I believe increasing fin/rudder size improves most last generation planes, not only Aspire. As an example, the Xplorer light carbon fuselage has an increased rudder size and moment while std x-fuse comes with original rudder asembly from 2008.

Roy presented the structure quite nicely. Not too difficult to implement...

Quote:
Originally Posted by roydor View Post
l
Tuomo,
the diagonal structure is extremely rigid for torsion because the ribs are covered with 0.2 mm carbon cap strips. It's so torsionally rigid that you don't need a d-box structure it support it. You can simply cut the skin 4-5 mm after the hinge and glue the built up stab to the skin (thatís what I did). My only recommendation is to build the rudder before you cut the existing one off, just in case you get in trouble with the build.
BTW, the rudder weighed around 7 grams before covering and took me about 3 hours to build
More than using orignal structure as a d-box I want to preserve the hinge line and horn hard point.

I have one spare rudder from crashed fuselage. I can use that for practising the build. Maybe make the d-box very small, just enough to fuction as a base for the open structure.
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Old Mar 02, 2013, 11:36 AM
In F3J size does matter!
roydor's Avatar
Israel
Joined Nov 2006
835 Posts
Finished my light F5J fuse and the model weighs in at 1950 grams with a modest setup.
I ended up having to add 50 grams of lead in the nose for the proper CG and now I'm thinking of building a lighter elevator to knock off 20 to 30 of those and to replace the motor with a slightly bigger one to give me a little more power for launching ballasted (ya, I have a ballast provisions same as my F3J )

The model also has a longer tail boom, about 7 cm longer than previous models and it feels fantastic! Easier to fly and more responsive. I like!
This is actually my lightest model as I still haven't got to building an F3J fuse for the wing which should bring it to a 1850 gram model.
It's interesting to fly this model at a lower weight than usual (F3J weight is 2080)
I flew the same wing on a calm day with the new fuse (1950) and the older F5J fuse (2100) and I must say that as far as performance go I don't feel I'm gaining any considerable performance with the lighter fuse but the feel and response is nicer, signals air a tiny bit better perhaps but it's mostly an issue of work load rather than performance.

Today we had an F5J competition, first of the year and I flew the new wing and fuse exclusively.
First round was a bust, caught massive sink and landed out which made for my throw out (4 out of 5) next 4 rounds I got 4 1000 and won the competitions.
We had strange conditions today, with clear skies and no wind to a very light easterly wind (always bad thermals when the wind is from the east) we had some nasty sink and surprisingly light thermals for the strength of the sink and one needed to find the light thermals and "stick with it" for a long time before they started to intensify and "pop".
I took some low launches against the top competitor with 54 meters being the lowest and another 62 and 104, other two flights were more conservative with 138 and 170 (the throw out).
Landings were rusty but managed to get in the game after a couple and finished with three F3J quality landings right on the mark so I'm good with that, no dorking the model though as it has this spinning thing in the nose which doesnít like that .
all in all very happy with the model and the competition.

Roy
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Old Jun 22, 2013, 02:55 PM
In F3J size does matter!
roydor's Avatar
Israel
Joined Nov 2006
835 Posts
A couple months ago, during an F5J competition I had an unfortunate midair with another pilot. I was having a very good competition up until the midair and I just managed to climb to 200+ meters from a 50 something motor climb (which would have given me the 1000 with a decent landing) when another model smashed into the base of my rudder, breaking the tail boom off and sending me into an uncontrolled tumble. Ironically, the model came to rest in cemetery! Wings were damaged in the impact, spar broken, leading edge split on both tips, two servos striped and a big chunk mangled leaving the wing torsionaly unsound.

After a deep examination I decided it was repairable. Attached are pics of the repair of the wing.
I cut out the mangled part of the skin and removed the web from beneath the broken spar cap. I built a mini spar and glued it between the two spar caps to fix the broken spar. I fixed the leading edge as well as I could and replaced the mangled dbox with a dbox from a wing panel that I messed up when I built the first wing (I knew their was a reason I saved it all these years )

At the moment the wing needs some cosmetics but seems structurally sound. Next part will be to fix the rudder and replace the tail boom. Hopefully it will be flyable in a couple of weeks.
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Old Jun 22, 2013, 06:37 PM
AZ Outback
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Joined Dec 2000
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Nice work on the repair, given the nature of the construction, a real time saver. The more colors on a ship the better, then something will always work on a given day;-)





robert
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Old Jun 22, 2013, 06:40 PM
AZ Outback
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Joined Dec 2000
1,344 Posts
Just noticed the boom, here people have used heat to remove damaged booms from fuselage bodies.
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Old Jun 24, 2013, 02:01 PM
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Harbor City, CA
Joined Oct 2003
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Sorry to hear of the misfortune, but glad to hear it is able to be repaired!

R,
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Old Jun 24, 2013, 03:40 PM
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United States, CA, Torrance
Joined Apr 2006
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Heat wont work. Parts are made of epoxy, booms are usually glued on to pods with epoxy, you will just burn melt the whole thing.
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Old Jun 24, 2013, 03:50 PM
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San Diego
Joined Aug 2004
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Quote:
Originally Posted by ak79 View Post
Heat wont work. Parts are made of epoxy, booms are usually glued on to pods with epoxy, you will just burn melt the whole thing.
It depends on if the boom was glued to the pod with an epoxy with a lower glass transition temperature. My guess in this case it wasn't, but I'm sure there are plenty of Supras out there with booms glued in with 30 minute epoxy that would come right out with some carefully applied heat. . .
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Last edited by Kiesling; Jun 24, 2013 at 11:33 PM.
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Old Jun 24, 2013, 05:04 PM
Detail Freak
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Harbor City, CA
Joined Oct 2003
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Is that a consideration in new construction, Tom?
Might you recommend 15 or 30 minute hobby epoxy for that reason, as opposed to MGS or other laminating epoxy?

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Old Jun 24, 2013, 05:24 PM
AZ Outback
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Joined Dec 2000
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I have been using West systems flex epoxy which is a 7 hour full cure, so it would be interesting to see if it loosens with heat, over a full temp cure of a production epoxy part.
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Old Jun 24, 2013, 05:27 PM
Detail Freak
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Harbor City, CA
Joined Oct 2003
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I have some of that as well....
I suppose for that style of fuse, one could always sand off the boom on the pod stub and get down to boom re-installation that way...

R,
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Old Jun 24, 2013, 07:27 PM
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San Diego
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Quote:
Originally Posted by target View Post
Is that a consideration in new construction, Tom?
Might you recommend 15 or 30 minute hobby epoxy for that reason, as opposed to MGS or other laminating epoxy?

R,
Target
I wouldn't use a 15 or 30 minute epoxy just for the sake of being able to remove a boom at a later time. I may use West systems or West systems flex over MGS or ProSet laminating resins because they are a bit thicker and more suited to bonding two parts together.

With a carbon boom it shouldn't be too hard to heat the boom up a little bit away from the joint and let the heat conduct through the boom to the joint. I suspect that it shouldn't be too difficult to heat up the joint without damaging the pod to get the boom out.

Or you could just sand it out - you will need to clean up the interface with the heat method so the heat method may not save all that much time anyway.

I know that the heat method worked great on removing the brass inserts from Tragi wings with broken control horns . . .
Tom
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Old Jun 24, 2013, 07:58 PM
Detail Freak
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Harbor City, CA
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Copy all, thank you.

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Old Jun 24, 2013, 11:09 PM
In F3J size does matter!
roydor's Avatar
Israel
Joined Nov 2006
835 Posts
I plan to carve out the big pieces and then Dremel out to rest. The interface from the pod is very robust, the boom is very thin in comparison and with a little patience I should be able to sand off all the pieces without damaging the pod. Same as I did in the tail.
BTW, I used high quality structural epoxy in joining the pieces, no 30 minute epoxy for me, I’ve seen quick setting epoxy soften and melt on a hot day with sun exposure and I don’t want my model disintegrating on me in the Israeli summer
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Old Jun 25, 2013, 05:41 PM
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Harbor City, CA
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Sounds very reasonable, Roy.
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