Mountain Models EVA Bipe

[jaredstrees]

Morning Everyone! Just started on this kit. . Quick question about the power system. What motor have you been using on this plane? I imagine about a 400 size 1200kv ish would work.

So far this kit has me smiling. The cuts are better than they were in my switchback sport. There are only two issues I've had so far. First was the landing gear. It is unusable in its current state. Holes not drilled to center both at the mounting point nor for where the wheel attach. No matter. I have the material to make new gear. The second was the triangle stock. There should have been two but only one showed up. And it was cut wrong. So I 3D printed a triangle stock balsa cutter and made my own.
Other than that it has been smooth sailing. I had the top and bottom wings done in a day. It seems that these wings were easier to build than those on the switchback. Not entirely sure if it is a better design or that I had a little experience after just building a MM kit. Most likely a combination of the two.

Here are the wings, the have since been sanded and set aside for covering.


Fuse is in progress, pics to come, but I'm not in a hurry with this kit, plus ya'll are at flite test so I'm jealous.

I plan to cover her in solite, have dark green for the top and cream for the bottom. Thanks for watching!

 

[rockyboy]

Awesome!!

I haven't built the EVA bipe yet but that motor sounds like a good idea

 

[Turbojoe]

I'd have to dig my bipe fuse out but I'm pretty sure it only has an E-Flight Park 480 or possibly a Scorpion 3008 motor. In either case there is more than enough power. Surprised to hear of your issues with MM kits. I've built dozens and had no problems. Glad to hear it was just little things for you. Maybe Brian just doesn't have time to devote to the business like he used to. Hopefully someone will step up and buy the business and he won't just close it and become yet another economic statistic.

My latest EVA build is as a twin using the "Sport" wing and it is tricycle gear. Build has been complete for a while. Trying to decide on a color scheme plus I'm working on a plug to make a "no motor" cowl. That cowl is what has been kicking my butt for a long time now. This is yet another long term project so I only mess with it when I get the itch.

Joe

 

[Turbojoe]

Boy, I was way off..... I just pulled out the EVA Bipe and checked. She has a Scorpion 2215-18 with an APC 10x5E prop. Specs say over 200 watts. I haven't flown here in several years but I remember unlimited vertical was not an issue. On this bipe I cut off the 3D tail feathers and scratch built slightly larger SwitchBack tail feathers. I much prefer the rounded look to the 3D stuff. Still haven't re-maidened her yet......

Joe

 

[Try-n-glide]

I used a Sunnysky 2212 980kv on my EVA sport. Had to build some standoffs to make the cowl fit correctly. Power was more than enough with a 10" prop. Later upgraded to the same motor in 1250kv and frankly it was way overkill in the Sport but in the Bipe maybe it would be a better fit.

Strongly suggest upgrading the EVA landing gear mount by gluing a thin section of model plywood to the base of the fuselage. As designed I just don't see it holding up to less than perfect landings. With the plywood reinforcement it will take about anything.

The other thing I really wish I did to mine is reinforce the fuselage ribs along the battery tray. They break if you look at them funny. Just a thin square balsa strip glued to the edges would do it. Some 1/32" ply strips would be better. Same with the leading edge of the horizontal stap. it REALLY needs a strip of thin carbon fiber or even thin ply to strengthen it _before_ installation. Mine cracked where it meets the fuselage.

Post updates with pics!

 

[jaredstrees]

I'll keep it in mind. Thanks for the tips!

 

[jaredstrees]

Main fuse construction is complete, as are the tail feathers. Fuse has been sanded, tail feathers not so much.

Next up is the battery box, but we are at hold until next week. I might not get Flite Fest, but I'm going fishing!

 

[jaredstrees]

Alright! So I've completed the canopy frame and front turtle deck. Sorry, no pics of that as it was late. Also Went ahead and covered the ailerons. I need to find some paint to match the colors on this bird and wanted to actually see the colors. It's hard to tell on the roll so she got a little color. The tops of the ailerons are the dark color and the bottoms are the cream. I was hoping the dark would be a little more green, as it was listed as dark green. It might be more green in the sunlight, but under the house lights it's almost black.



Tonight I plan to get the canopy fitted. That seemed to be harder than I thought to get looking right on the switchback, hopefully this one goes easier! If I get the time this weekend she may be near complete come Monday!

I do have a question about this solite. I want to use the crème to make some stripes for the fuselage sides and wing tops. Is there a good way to adhere the crème solite to the dark solite? I think I read somewhere to float it on a little windex then use the iron to adhere it? Recommendations?

 

[rockyboy]

I've had very good luck with floating it on with a little windex, squeegee out the excess, let it dry over night, and then iron it down the next day. Not sure if it could be sped up and all done at once, but the two day process worked well for me.

I'd recommend trying the technique out on some of the leftover sprues (the waste balsa sheet material that the parts popped out of) - especially layering the cream over the dark. My experience with the cream is it will be very transparent and show the dark color through very strongly. Laying down a base of the cream and then the black going over the top, or joining together the cream and black pieces with an iron on a piece of class first with just a small edge overlap, and then putting the joined pieces over the frame could help - but either way give it a test on some scraps first

 

[jaredstrees]

Got it, and I am worried the cream will show the black through as well. I have some solar trim in white that would cover the black well, but I'd love for the accents to be the same. Might just have to check if they have the solar trim in crème. That trim is a lot more opaque than the solite!

 

[jaredstrees]

So I did get the canopy frame finished and canopy trimmed last night. I need to cover the front turtle deck/canopy frame before I can glue down the canopy.



Couldn't resist a little mock up either!



I plan to start covering her up tonight. Getting close to final assembly!

 

[rockyboy]

Looking good!

 

[jaredstrees]

Not as much progress as I hoped for over the weekend. I did manage to get the fuse covered along with the tail feathers. Hope to start the wings tonight. For the most part this solite is decent to work with, very light weight and easy to get the wrinkles out, but man do you have to be careful when trimming it or you'll tear it! I'm not the best at curves yet, but managed to get it done with very few wrinkles.



Now to find some matching paint and get the cowling and some other bits painted up!

 

[jaredstrees]

Well, I do not like larger pieces of solite! Once it starts to fold and stick to itself it becomes incredibly hard to work with! Those smaller pieces are much easier to deal with. Also, wow! Will this stuff tear easily if your blade isn't super sharp or what! That being said, I did manage to finish covering the wings last night. All that is left is some white trim for the tops and sides of the wings, install the servos in the lower wing, paint and attach the wing cabane struts. Also I'm going to add a small strip of the dark solite on the leading edges to give them a cleaner look.



I'm still searching for the right colors of paint for the cowling, but I'm going to do the cabanes in white to match the trim and canopy. Tops of both wings will also get a stripe of white to match the strip that will go the length of the fuselage.

Getting closer! Hope to install the wing servos tonight, and get the trim on so I can set these aside for final assembly.

This plane is certainly more time consuming than the SB sport (duh, two wings!). There is a lot more to it's complexity than an extra wing though! Been a great learning experience so far!

 

[rockyboy]

Looking good! As a tip for the next time you're working with larger so-lite pieces, a little puff of talcum baby powder will help prevent it from sticking to itself, but not get in the way of the iron on adhesive.

 

[jaredstrees]

Getting closer! I’ll snap some more picks tonight.

I will say that the bottom wing is giving me fits. The spar does not fit through the holes in the ribs. Way to tight. I should have checked this before I covered the wing. I’ve used a really long drill bit to drill out the correct hole placement in the ribs. This got the spar to fit, however it did not fit flush with the fuse. There was a 1/8” gap between the wing and the fuse. I was able to fix that be adding a reinforcement plate to the fuse and sinking a screw through it into the wing. I added a little gorilla glue for strength. This is going to make the bottom wing harder to remove, but unless I need to do repairs the wing wasn’t coming off anyway.

Other than that progress has been slow due to life. So many things going on at the moment!

 

[jaredstrees]

Here you can see the gap. I hope to take a pic or two tonight where that is gone!

 

[jaredstrees]

So, while I was sorting the wing issue one of the captive nuts came out on the inside or the wing. Oh crud. No real issue though. Removed the servo, managed to get the nut in the right place and used some large washers to help disperse the force of resinking it. Fun times!

 

[jaredstrees]

I also finished setting the bottom wing in place so I could get the top wing mated to it and set the placement for the cabanes. You can see here that the gap is now gone!



However, there is another issue. The wing top does not center on the plane. It is about 1/8" of an inch starboard off center. I plan on adding a 1/8" strip of balsa on each side of the wing struts to shift the wing to the port side a little. Has anyone else experienced this and how did you address it?

 

[rockyboy]

So, while I was sorting the wing issue one of the captive nuts came out on the inside or the wing. Oh crud. No real issue though. Removed the servo, managed to get the nut in the right place and used some large washers to help disperse the force of resinking it. Fun times!

View attachment 112069

A touch of CA on those captive nuts can do wonders for keeping them in place

I also finished setting the bottom wing in place so I could get the top wing mated to it and set the placement for the cabanes. You can see here that the gap is now gone!

View attachment 112070 View attachment 112071

However, there is another issue. The wing top does not center on the plane. It is about 1/8" of an inch starboard off center. I plan on adding a 1/8" strip of balsa on each side of the wing struts to shift the wing to the port side a little. Has anyone else experienced this and how did you address it?

That might actually be a design feature - one of the ways designers can avoid adding motor thrust angle is to have one side of the wing a little longer, which adds a touch extra drag on that side counter acting the yaw force of the prop wash (at least I think that's the theory behind it). I didn't notice if my EVA has an off center wing, but the Telemaster I built this spring does have an off center wing by design too.