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Sep 20, 2019, 11:56 AM
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Randy Reynolds's Avatar

2M electric


Howdy Crash,

I used to be a luthier for 20 years and the wood thst bothered me the most....balsa, wouldn't you know. Same for my son. Both of us have to wear one of the quality respirators and that blocks most or all of the probelms. Also an old woodworkers trick is to take the airhose, open up all the windows and just blow out the shop regularly....and that seems to help as well.

Anyway the reason for contacting you is to ask about any advice on converting the standard line launch fuse to electric. I have done the electric fuse and it sure works but it is really porky. I'm wanting to use one of those quad motors that are light and pretty fast on smaller props. Thanks for any tips you might have run across.

Randy Reynolds
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Sep 20, 2019, 12:51 PM
Registered User
Quote:
Originally Posted by Randy Reynolds
Howdy Crash,

I used to be a luthier for 20 years and the wood thst bothered me the most....balsa, wouldn't you know. Same for my son. Both of us have to wear one of the quality respirators and that blocks most or all of the probelms. Also an old woodworkers trick is to take the airhose, open up all the windows and just blow out the shop regularly....and that seems to help as well.

Anyway the reason for contacting you is to ask about any advice on converting the standard line launch fuse to electric. I have done the electric fuse and it sure works but it is really porky. I'm wanting to use one of those quad motors that are light and pretty fast on smaller props. Thanks for any tips you might have run across.

Randy Reynolds
Randy, best thing I can give you is the rather superficial description I give on this page in the 2m thread, https://www.rcgroups.com/forums/show...tition/page112 see post 1672

Biggest thing to note is, the floor of the fuselage tapers toward the nose in the line launch, so you have to saw out the floor back to the point before the taper starts, and keep the sides parallel to the firewall because, well, because you need to accommodate the width of the firewall. I made the firewall from plywood. One thing to consider, which I did not, is forward of the firewall you need a triangular piece in each corner, so you can sand down the outer corners to a radius and contour it down to round and match the round spinner on front. I didn't do that on my conversion and so it had a sort of blunt nose behind the spinner. (You can see that at about the 30 second point in the video on that page.) On the electric kit, Corky supplies the balsa triangle piece for that purpose.

Since the servos are forward of the wing, there could be balance issues, I moved my receiver underneath the wing and was able to slide in an ESC and use a long narrow battery forward of the servos. https://alofthobbies.com/tattu-450-long-3s-75c.html Just check your balance. Good news is, if it is a tad nose heavy it doesn't take a lot of weight on the tail to balance.

Hope this helps.
Last edited by Crashbound; Sep 20, 2019 at 01:02 PM.
Sep 20, 2019, 02:41 PM
I fly, therefore, I crash!!!
SteveT.'s Avatar
Putting masking tape where you are going to drill also helps a lot, especially on the back side when drilling through wood, and of course clamping a block to the back side also helps. And even though they are Forstner bits, and supposedly don't need a center punched starting point, I always center punch it as it gives a more clear center.

SteveT.;
Last edited by SteveT.; Sep 20, 2019 at 03:00 PM.
Sep 20, 2019, 06:50 PM
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Randy Reynolds's Avatar
That will help, Thanks a lot!

Randy
Sep 20, 2019, 09:00 PM
Registered User
Quote:
Originally Posted by SteveT.
Putting masking tape where you are going to drill also helps a lot, especially on the back side when drilling through wood, and of course clamping a block to the back side also helps. And even though they are Forstner bits, and supposedly don't need a center punched starting point, I always center punch it as it gives a more clear center.

SteveT.;
Haha. I thought about that AFTER I drilled it. Usually when drilling wood I would clamp or hold it tightly against a sacrificial block underneath. I did drill on a block but really can't clamp or hold the wing too tightly. Seemed I read somewhere about masking tape, which is what I thought of. Glad you confirmed it wasn't just something I dreamed. Thanks!

Quote:
Originally Posted by Randy Reynolds
That will help, Thanks a lot!

Randy
Stangely, I still have the nose of that fuselage and it is exactly 3" that I whacked off. I measured it tonight. Don't know why I still have that piece in my shop. I crashed that plane and salvaged only the wing and tail surfaces & trashed the fuselage. I ordered a new (electric) fuselage kit from Corky to rebuild everything.
Sep 21, 2019, 10:16 AM
Registered User

????


Okay couple questions.
First this is probably going to be one of those "Duh" obvious answers because I must be missing something obvious. But what are these hex screws of varying lengths for? And those little rectangular plywood pieces?

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Description:

For clarity. I am to epoxy the blind nuts in these balsa pieces and then into the holes on the pylon from the inside? I just want to make sure, it seems that balsa spacer could become "soft" over time with pressure from the wing tightening, mounting, unmounting, torquing, flexing etc. This correct?

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Also as I proceed on the tail surfaces, here is my plan.
Mount the v-stab mount, attach the stab, epoxy on fin/rudder @ 90 to stab. After that THEN attach pod to boom with wing mounted on pod to make sure of wing/stab/rud square. On the right track here?
Sep 21, 2019, 10:49 AM
Registered User
Just received my 3.5M YJ, awesome looking kit. Thanks Corky, can't wait to get it in the air.

I'm trying to get the electrical components recommended on the website. The speed control (TURNIGY Plush 30amp Speed Controller w/BEC) is no longer available, they recommend a replacement Turnigy Plush-32 30A Speed Controller w/BEC. Will this work, specs are a little different?

TURNIGY Plush
Cont Current: 30A
Burst Current: 40A
BEC Mode: Linear
BEC : 5v / 2A
Lipo Cells: 2-4
NiMH : 5-12
Weight: 25g
Size: 45x24x11mm

TURNIGY Plush-32 (recommended by Hobbyking)
Amps: 30A
Cells: 2~4S
Voltage: 8.4~16.8V
BEC: 5.5V / 4.0A
BEC type: SBEC
Timing: Auto
Cutoff Voltage: 3.2V
Frequency: 48MHz
Weight: 24.5g
Size: 36x23.5x10mm
Sensored/Sensorless: Sensorless
Sep 21, 2019, 10:59 AM
Registered User
whacker's Avatar
Crash

Don't glue, those little nut assemblies to the fuse


For clarity. I am to epoxy the blind nuts in these balsa pieces and then into the holes on the pylon from the inside? I just want to make sure, it seems that balsa spacer could become "soft" over time with pressure from the wing tightening, mounting, unmounting, torquing, flexing etc. This correct?


Until you have your wings andfuse at the least build so you can check alignment

My view as well is the entire assembly should be on the firm side,

Spare parts. Maybe

Some got a Bag of Gummi Bears that got falsely allocated on Corky's production line.

You lucked out and got some "goodies" for your tool Kit.

Everyones a winner

when they Build a Sailplane




whacker

in the sny Waughs River Valley
Sep 21, 2019, 11:52 AM
AECS USN RET. P3 FE
allanp's Avatar
Quote:
Originally Posted by Crashbound
Okay couple questions.
First this is probably going to be one of those "Duh" obvious answers because I must be missing something obvious. But what are these hex screws of varying lengths for? And those little rectangular plywood pieces?

Attachment 12579531

For clarity. I am to epoxy the blind nuts in these balsa pieces and then into the holes on the pylon from the inside? I just want to make sure, it seems that balsa spacer could become "soft" over time with pressure from the wing tightening, mounting, unmounting, torquing, flexing etc. This correct?

Attachment 12579529


Also as I proceed on the tail surfaces, here is my plan.
Mount the v-stab mount, attach the stab, epoxy on fin/rudder @ 90 to stab. After that THEN attach pod to boom with wing mounted on pod to make sure of wing/stab/rud square. On the right track here?
Extra screws are from CLM for different thickness horizontal stabs.
Ply pieces are to reinforce the servo tray,it gives servo wood screws more "bite"
Round balsa pieces go on the outside of the wing mount to "pull" the "T" nut tight against the mount. SEE post 842
Sep 21, 2019, 01:32 PM
Registered User
Quote:
Originally Posted by allanp
Extra screws are from CLM for different thickness horizontal stabs.
Ply pieces are to reinforce the servo tray,it gives servo wood screws more "bite"
Round balsa pieces go on the outside of the wing mount to "pull" the "T" nut tight against the mount. SEE post 842
Okay, makes sense thank you.

However, Matt's post you referenced(#842) ; He actually made his own balsa spacers, and used the ones that are supplied as a temporary spacer on the outside. I don't think the T nut epoxies directly on the bottom/inside of the pylon, especially considering those "spikes".

edit: Found it! Post #568 pg. 38
Last edited by Crashbound; Sep 21, 2019 at 01:52 PM.
Sep 21, 2019, 05:00 PM
Sonoran Laser Art
Thread OP
The T nuts epoxy into the balsa pieces. It will leave just enough spike to get into the bottom of the pedestal. You may have to trim the edges once together to get the back one in. Once cured the T Nut/balsa assembly is epoxied under the pedestal. Put a bolt in to hold them up snug while the epoxy cures. The early ones did not have the slots cut for the spikes and it was easy break them. These work much better.

I have never had a t nut come loose

On the servo Tray the servos go in from bottom. Glue a little squares at each end on top for the screws to go in. Like Allen said.

On the V Mount, yea the metal screws come with the stab mount. They are good to chase the hole but use the nylon screw that I put in the same bag.

I need to look at the ESC question. Sounds like it’s a replacement. Didn’t know they changed.

What did I miss? Been out flying my 3.5 all morning in a F5J contest. Had quite a few rounds getting my time (mostly) and mostly 40-50 point landings with my trusty spoiler.
Sep 21, 2019, 05:55 PM
Registered User
Thanks Corky. I spent a beautiful day for bike riding or flying...indoors building. I'm anxious to get it in the air!
Last edited by Crashbound; Sep 21, 2019 at 08:58 PM.
Sep 21, 2019, 07:20 PM
Sonoran Laser Art
Thread OP
Quote:
Originally Posted by jgm911t
Just received my 3.5M YJ, awesome looking kit. Thanks Corky, can't wait to get it in the air.

I'm trying to get the electrical components recommended on the website. The speed control (TURNIGY Plush 30amp Speed Controller w/BEC) is no longer available, they recommend a replacement Turnigy Plush-32 30A Speed Controller w/BEC. Will this work, specs are a little different?

TURNIGY Plush
Cont Current: 30A
Burst Current: 40A
BEC Mode: Linear
BEC : 5v / 2A
Lipo Cells: 2-4
NiMH : 5-12
Weight: 25g
Size: 45x24x11mm

TURNIGY Plush-32 (recommended by Hobbyking)
Amps: 30A
Cells: 2~4S
Voltage: 8.4~16.8V
BEC: 5.5V / 4.0A
BEC type: SBEC
Timing: Auto
Cutoff Voltage: 3.2V
Frequency: 48MHz
Weight: 24.5g
Size: 36x23.5x10mm
Sensored/Sensorless: Sensorless
The Plush 32 is the newest version. It looks like it uses a new programming card too. The card shows under $8.00. I would get that too.
Sep 22, 2019, 12:49 PM
volare est vivere
ray foley's Avatar
hi there from Toledo!

I had no luck with the Tnuts mounting in soft balsa in my early version YJ3m. The balsa shattered and so did the replacements I tried to make.

So I took two 1/2" od, 1/4" id, 1/4" thick nylon standoffs and put them on the oiled mounting screws. These were installed from the outside to pull the prongs of the Tnuts flush with the inside top of the pedestal without the balsa pieces. I had to modify the Tnut in back to fit in the limited space in rear of pedestal. i also used my Dremel to clear away some excess material in the rear of the pedestal.

Then I mixed up some JB weld 5 minute and slathered it around the Tnuts and the top of the pedestal from the inside of the pedestal and let it set up. I repeated the slathering to fill in any gaps and bury the prongs so as to help set the Tnuts permanently.

The end result: A slightly heavier Tnut installation, perhaps. A permanent and secure installation, absolutely.

ciao rjf
Last edited by ray foley; Sep 23, 2019 at 12:40 PM.
Sep 22, 2019, 07:27 PM
Registered User
Been busy this weekend. No flying though I DID get out today for a short bike ride. Things are coming along.

I made a template for marking my pylon for the wing bolts out of a scrap of plywood, marking the wing holes on center then transferring it to the pylon. I covered the top of the pylon with blue tape and marked the center line, cutout, and bolt holes. Like Matt did on pg 57, post #842 of this thread. Once that was all drilled and cut, I sanded a bit on the top to flatten it out a bit. (See same post mentioned above, pg. 57) I did stop well short, not knowing just how far to go.

I also really like Larry Weller's removable servo tray, and I like the way he mounted the servos lying flat on their side. Just makes sense to me that would be way easier to hook/unhook the clevis' on the servo horns. Just a couple screws and the tray slides out. Tracing Corky's tray onto plywood I cut it and then I just cut short sections of oak, CA'd then screwed through the bottom of the ply. servos mount to those I'll put some type of sheet in there to direct the wing servo wires away from these servos, again per Larry Weller though mine isn't nearly as neat. (not sure where his is in this rather lengthy thread)

Also as Ray mentioned above, I cut down the T-nut and balsa spacer for the front of the pylon. Epoxied everything in and screwed the wing down to pull the nuts up into the holes and in alignment with the wing holes. I greased up the wing bolts with vaseline so as not to to accidentally epoxy them in. In spite of what I thought was a good fit, I ended up without the forward nut pulled up to the bottom of the pylon so there's a gap. I mixed some epoxy with cabosil to thicken and filled in the gap. Ray left out the spacer altogether and used JB Weld to fill the gap. Don't think it's critical as long as everything is seated and secure.

Descriptions in photos.

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Description: Marking scrap piece of ply to center of wing mounting holes. Name: IMG_5110.jpg
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Description: I use that as a template to mark drill holes on the wing pylon. Name: IMG_5111.jpg
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Description: Covered with blue tape, ready for cutting and drilling



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Description: Cutting access to servo tray area. Name: IMG_5113.jpg
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Description: Cut and drilled.   I also noticed the pedestal/pylon top is less that flat.  So I sanded it a bit to fair it out but wasn't sure how far I could go. Name: IMG_5117.jpg
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Description: My servo tray with oak posts CA'd and screwed from bottom.

This evening I covered my fin/rudder, attached the stab (epoxied on that mount yesterday), and glued the verticals on the boom. I marked a line on the back of the plans with a straight edge, laid steel tube under the stab and shimmed to make the stab level, aligned the boom over the line to have a reference, then epoxied on the fin. I put a square on the level horizontal and eyeballed to make sure it is 90 to the stab. Also laid a straight edge along fin to make sure it is square to the boom.

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Description: Epoxying on the verticals. Name: IMG_5120.jpg
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Description: How I squared up everything.


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