UMX Tri-Star 180 EDF - RC Groups
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Nov 03, 2017, 10:20 AM
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Ian Kunz's Avatar
Build Log

UMX Tri-Star 180 EDF


For a little background before I get started on the building.

This is a scaled down version of Sig's .15 size 2-stroke model by Leroy Satterlee which I have as electric conversion. I like the full size version so much that a few years ago I built my first micro version of it powered with a Parkzone UMX F-27 Stryker system. It was a quick build and as such, not the strongest plane. So for my new one, I decided to learn how to use CAD and draw out my first plane and solicit my dad and his laser to cut it out.

A few changes that I made were power source (obviously) and a single central mounted vertical stabilizer with a rudder rather than two wing tip mounted vertical stabilizers with no rudder. The reason I did these is because I thought it would make for a cool EDF and because on the full size model the lack of rudder can make interesting last second corrections on landings. I am also using this plane as a test platform in case I want to super size it in the future.

It will be powered by a single E-Flight 28mm fan unit on 2S.
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Nov 03, 2017, 10:24 AM
AndyKunz's Avatar
Subscribed!
Nov 03, 2017, 10:44 AM
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ditto
Nov 03, 2017, 03:39 PM
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Ian Kunz's Avatar
All the pieces needed to build it are on just over one sheet of 1/16 balsa and a piece of scrap 1/16 ply.

I started building last night with the duct bottom. I glued some hand trimmed 1/8 triangles to bottom edge of the sides. Then I glued the formers F-2 through F-5 to one side using the alignment tabs . F-2 is one of the two plywood formers on the model. It was a little fragile coming out of wood and ended up breaking right at corner but it was still good enough to glue to the sides. After letting the glue dry on the one side, I fitted and glued on the other side and held together for a few minutes as the formers are fragile enough that clamping would probably break them. After that glue was dry, I glued on the bottom sheet. When that was done drying, I glued on the two triangular intake doublers on the inside the front of the duct. These serve as covers for F-2 that can be sanded down in the front to help reduce drag as well as stiffen the whole intake area for landings.
Nov 04, 2017, 10:24 AM
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turbojoe's Avatar
Please tell me this is going to be kitted! C'mon Andy, you've got that new laser!

Always missed out on the full sized kits when they would come up for sale then about a year ago I snagged one still sealed in the box. Paid too much but at least I finally have one. Plans are out there to scratch build the fuse but nobody makes the foam wings. For now I just look at the box, unwilling to build it and maybe never find another. (I'm a bit of a kit hoarder) A UMX size should be fun. I already have a full set of UMX Pitts and F-16 electronics I picked up a while back. My UMX Habu doesn't impress me much for climb performance so I'd probably go pusher rather than EDF if I can get my hands on one of these kits.

Joe
Nov 04, 2017, 11:01 AM
AndyKunz's Avatar
The A-10 fan is much better than the F-16. See if you can find one of those, Joe. As for kitting, that's up to Ian. We will have to get video of both the pusher and EDF ones flying.

Andy
Nov 04, 2017, 01:11 PM
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turbojoe's Avatar
Thanks Andy! The A-10 fan is EFLDF180M2 and HH still shows it available but aside from wire length it looks like the same 13.5kv motor as the F-16. Is the new fan a drop in for the F-16/Habu? If so I may grab two and update the Habu while waiting to see if the Tri-Star gets kitted.

Joe
Nov 04, 2017, 01:14 PM
AndyKunz's Avatar
I think they upgraded them with each plane. The F-16 is better than the MiG, but I don't know about the Habu. I know they did a lot for the A-10 fan, though.

Andy
Nov 04, 2017, 03:32 PM
AndyKunz's Avatar
Ian asked me to post photos of his full-size Tri Star (from the Sig kit) with his UMX pusher prop one. The small one is a hoot to fly, even without stabilization. Because of the solid sheet (airfoiled) wing, it's a bit heavy, and that's one of the things he was fixing with the EDF version.

Andy
Nov 04, 2017, 08:25 PM
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Ian Kunz's Avatar
Thanks Dad.

I don't know if we have any video of the pusher flying. If we do, it's on your computer.
Nov 05, 2017, 08:09 AM
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30mm EDF fan performance


Quote:
Originally Posted by turbojoe
Thanks Andy! The A-10 fan is EFLDF180M2 and HH still shows it available but aside from wire length it looks like the same 13.5kv motor as the F-16. Is the new fan a drop in for the F-16/Habu? If so I may grab two and update the Habu while waiting to see if the Tri-Star gets kitted.

Joe
Hi Joe,
I did some static testing on the Habu, MiG & A-10 fans a few months ago. I collected a spreadsheet full of data, but the bottom line was that the A-10 fans produced an average of 64g thrust per fan, the Habu produced about 53-54g, and the MiG about 47g. Mechanically they all look about the same, but internally something is different. Based on the sound produced by each of them, I'm guessing that the improvements were better/cleaner fan blades and/or bearings.
Tom
Nov 05, 2017, 09:44 AM
M0unt@in M0del$ minion
turbojoe's Avatar
Quote:
Originally Posted by tkunz
Hi Joe,
I did some static testing on the Habu, MiG & A-10 fans a few months ago. I collected a spreadsheet full of data, but the bottom line was that the A-10 fans produced an average of 64g thrust per fan, the Habu produced about 53-54g, and the MiG about 47g. Mechanically they all look about the same, but internally something is different. Based on the sound produced by each of them, I'm guessing that the improvements were better/cleaner fan blades and/or bearings.
Tom
Thanks Tom. 12 grams doesn't sound like much but at these power levels that's significant! Looks like it's worthwhile to upgrade the fan. Not a 1 to 1 thrust ratio on the Habu S but should still improve the climb rate. I'll order up a couple today.

Looks like we're getting the whole Kunz family in here.

Joe
Nov 05, 2017, 02:01 PM
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Ian Kunz's Avatar
It's a good thing I guess that I'm using an A-10 fan.
Nov 05, 2017, 03:19 PM
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turbojoe's Avatar
Quote:
Originally Posted by Ian Kunz
It's a good thing I guess that I'm using an A-10 fan.
Looking forward to hearing how the performance is. I just ordered two A-10 fans from Horizon Hobby on ebay. Got free shipping too! I already had a few non R/C things in my ebay cart so I decided to get it all in one PayPal payment. (plus I'm a cheapskate and I couldn't pass up the free shipping!) The Habu S is back on the bench opened up and awaiting the swap.

Joe
Nov 05, 2017, 05:26 PM
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Ian Kunz's Avatar
Got some work do be this afternoon. I decided to skip the trimming of the 1/8 squares into triangles as that was rather difficult. So I glued them on to the fuselage sides and then trimmed out the notches where the triangle corners of the formers go. I also did the same for the hatch sides.

After the glued dried on those I glued formers F-2 through F-5 to one side ensuring that F-2 was square. While I was dry fitting the sides together I accidentally broke F-5 at the center where it is weakest. Darn. Nothing a little glue can't fix. So then I glued F-2 to the other side using a square to keep it square. I'll glue the other formers into place later.


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