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Mountain Models EVA Sport Build Thread

rockyboy

Skill Collector
Yeah - there was a mostly steady headwind about 7-10 mph and she just went straight up it on about 3/4 throttle. Winds were a bit more variable up high, and that gust on landing approach that put her sideways about 20 feet scared the jeebers out of me. I couldn't be happier with the touchdown, but that last gust was all my nerves could take for the day - I packed up shortly after this. :)
 
Nice job! I'm no fan of flying mine in the wind but if I don't have an option I'll go ahead and toss a 2200mah pack in there. The extra weight helps dampen it a bit and she's more than capable of hauling the extra weight. That "V" in EVA really does mean Versatile! Gotta love this plane.

Joe
 

rockyboy

Skill Collector
A flight update: I put 5 batteries through her on Saturday and she was a beauty! Putting the 1800mah battery just 1 inch further forward from the maiden flight position made a big positive difference in handling. Every takeoff she likes to do the same 'reach for the sky' behavior and once she's airborne I actually have to push a little down elevator to keep the climb to 'two mistakes high' at a comfortable rate.

I spent most of the packs doing lazy circles around the field, with a couple interesting rolls recovering from loss of orientation. While the cream and black design looks dynamite on the ground, the cream is actually a little translucent in the sky and the black pattern on the top of the wing shows right through. To help with that, I've added some 2" wide white vinyl tape stripes with black borders on the bottom of the wings. Fingers crossed I can keep better track of her next time. Until I'm confident on visibility and orientation, I won't be intentionally heading up for any loops or anything else that would get her inverted.

She does bounce a little bit in wind gusts with an 1800mah pack, and on a couple flights I had to correct for a good bit of weather-vane behavior. Joe, I like the idea of trying her with a 2200mah pack - these sport wings give her plenty of lift, and it might help a bit with keeping her more solid in the sky.

Landing the EVA was a very new experience for me. I'm used to coming around on the base leg at low power and cutting the engine all together after making the last turn into the final decent leg. I usually try keep myself about 30-40 feet up (as measured by the height of the plane eating trees) on the base leg, and with most of my foamies and wings I can set the plane down within 20 feet of my position if I manage elevator and small throttle movements right. However, the EVA with the throttle cut at 40 feet up will float along down the entire length of the runway and still be 10 feet off the ground at the other end! I overshot at least 4 or 5 landing attempts, and twice ended up with touchdown a couple hundred feet away at the other end of the field.

I am happy to say that all landings were nearly perfect 3 pointers on the tricycle gear - very smooth - except for one. My one nose over occurred when she set down in a rough patch on the field and somehow the linkage to the nose wheel slipped. The nose wheel twisted sideways and the plane flipped over. The set screw did have thread locker - but somehow it still let the control rod slip out. But there was no damage to the plane, and the nose gear was easily fixed at the field and she went back up for a couple more flights after that.

TLDR; So in summary, she handles great, I'm learning new landing techniques, and she has taken a place as my favorite flying plane in the hangar right now. If you're thinking about building one of these, stop thinking and order the kit right now. If you haven't finished your build yet, stop waiting! You'll love how she performs. :applause:
 

Joker 53150

A thousand pints of lite.
Nice flight report, I'm glad you're happy with the plane! It's experiences like this that can get people hooked on balsa as there is so much more pride in actually BUILDING instead of simply assembling.
 
hehe just saw the maiden video. With the grass sitting as high as it did to the fuselage it looked like it took off with two wheels and came down with three at first. Looks like it glides in nicely as I didn't see any wing rocking you had to fight at all. Sorry about the see thru coloring though as that is a gorgeous combination sitting static.
 
You convinced me. It's been over 20 years since I built my Kadet Seniorita. I remember it being an incredible chore. Perhaps time has increased my patience......EVA Sport is back ordered........we'll see how long it takes before I am straining to see if there is a package on the stoop as I turn down my road.
 
Congrats on the good flights over the weekend! Keep playing with the CG. Like I keep saying all of my EVA's are just right when I can fly inverted with no to almost no elevator input. It still blows me away that a plane with so much dihedral can fly inverted so well but the EVA Sport does! With the right CG the plane is completely neutral.

Joe
 

rockyboy

Skill Collector
Thanks for the kind words and tips guys!

She's running a PowerUp 370 (2208/14T 1400kV) from Heads Up Hobby with an 8x4 prop.

I do still feel like other forms of putting an airframe together still count as building, but I feel the amount of satisfaction and pride of a good flight increase directly in relation to the amount of time spent on the creation. On the other hand, frustration at a poor flyer also seems to be aligned to hours spent too. :p
 
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Rocky could you explain the blenderm hinges to me. I have done CA hinges but it appears the control surfaces are too thin to cut in CA hinges. Ive never done a tape hinge and the instructions available online from MM are not terribly clear. Seems like you would run a strip of tape parallel w the hinge line, but looking online it seems people put a few small strips perpendicular to the hinge line and alternate top and bottom. Seems like a few strips of tape is no where near strong enough for a hinge. :confused:
 

Joker 53150

A thousand pints of lite.
Blenderm is a tape by 3M, which you can find at hobby shops or even at Hobby King. It's similar to medical/first aid kit tape, but is very flexible in just about any weather condition. I typically use it across the entire area to be hinged, and if the hinged surface is big enough I'll do both sides. It's not invisible, but once the plane is a few feet away or flying, you'll never notice it. It's available in 1/2" and 1" wide rolls, and for something the size of the EVA the narrow roll is perfect. So far I've never had it fail on me, and the first balsa planes I built with it 5 years ago are still going strong.

If the balsa structure is too thin for a regular hinge, like the tail surfaces on the EVA, the tape hinge works great. You can get similar results using covering material or even packing tape for the hinges, but I don't think these are as flexible or as long-lasting as Blenderm.
 

rockyboy

Skill Collector
Yep - what Joker said. :)

I also like doing the strip of tape parallel and covering the entire hinge line because it prevents any airflow from getting around on the other side of the control surface at the joint and creating the conditions for flutter.

The alternating up and down tape strips across the join line is when you want a Jacob's Ladder style hinge where the two surfaces are squared instead of one or both being beveled. I haven't had much luck with trying that yet - the two times I ended up with a lot of slop in the joint and went to another hinge type.

https://www.flitetest.com/articles/tape-weave-hinges

A whole 'nother hinge type that's interesting to look into is sewn hinges - I did this one one plane and it was very strong, almost no slop, and yet very free moving - before I put the control hinge on the ailerons and elevator just hung straight down when turned the plane over. I'm planning to use this technique again on WWI era models where the canvas look is appropriate.

https://www.flitetest.com/articles/improve-your-hinges-by-goin-ol-school
 
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I'm reading some of the threads on the EVA Sport while I wait for my kit. I ordered two roles of So-Lite per MM's recommendation. After reading I'm starting to question that decision. Sounds like it's really light, but not durable enough. I _occasionally_ have a rough landing. So are there some other covering options I need to look at as I put my shopping list together? MM has almost no selection of Solarfilm in stock which seems to be recommended over So-Lite.
 
The plane is plenty strong enough unless you fly it into the side of a building. Then no covering will help. Most of the dislike of SoLite (including mine) is because of the transparency of the so called opaque colors. Only black and blue are mostly opaque. The rest are borderline transparent. I prefer SolarFlim but I've also used a ton of SoLite. Solite is more prone to rips and tears but you can fix them with clear tape. Use the rolls you get and enjoy the build. You'll be just fine with the SoLite.

Joe
 

Joker 53150

A thousand pints of lite.
I would (and will) stick with SoLite on planes like this which are designed to be light weight. Standard covering can easily distort, bend, or even break the balsa. Yes, it's lighter weight and can be torn more easily than heavier coverings, but that's the price you pay for a light weight material. During summer flying, when grass and weeds are dry and brittle I've gotten small punctures in the SoLite from the thicker weeds. Fixing it is pretty easy, I just use a little clear Scotch tape.

Some find SoLite a little difficult to work with because it REALLY wants to stick to itself when you peel off the backing. Some talc brushed on fixes that issue quickly, although I've never personally tried it. Quite honestly, I love using the SoLite because it shrinks very well and it's easier to get clean edges than with thicker film. I've got planes that were covered with SoLite 4+ years ago with over 100 flights on 'em, and they are holding up very well.

So my opinion, try it out and risk a rough landing, it's better than shrinking heavier film only to find that you've broken the wing ribs in the process!
 
The UltraKote Parklite from hangar 9 is a little easier to work with, and still quite light weight. I just used some on a 42" Dumas Bird Dog. It does stick to itself a little, but nothing like the Solite. The white isn't particularly opaque either, but nothing that light is going to be very opaque.