Yak-55 3D Dollar Tree foam board build

[TooJung2Die]

That was some seriously smooth flying, It looked like a simulator!

Thanks! The only simulation is me trying to look like I know what I'm doing up there. Some loops, a wing-over, maybe a roll are the meager extent of my skills. Flying this kind of airplane makes more difficult stuff easier. I never did multiple rolls or outside loops before. Plus, I had over half an hour of video to edit down to those two minutes. The rest was embarrassing or boring.

 

[Chuppster]

Great job! That thing looks fantastic!

Have you considered moving your CG back? That might make it more maneuverable.

 

[TooJung2Die]

Have you considered moving your CG back?

I can move the CG around easily now that the battery is close to centered on the CG. It kinda feels on the edge of tail heavy the way I've been flying it. I think tail heavy is the way a 3D airplane is supposed to fly. But what do I know? I'm a total noob when it comes to 3D. Do you have any experience? I'll play around with CG and see what happens... if the wind decides to die down. It's been gale force the last few days.

 

[Chuppster]

I can't claim to be a good 3d pilot, but I have found that it's very hard to hover a nose heavy airplane. If I had your Yak I would inch the battery back until it didn't fly well anymore. That'll make it unstable and theoretically better at 3d.

 

[TooJung2Die]

If I had your Yak I would inch the battery back until it didn't fly well anymore.

I will. That sounds counter-intuitive and crazy but it makes sense if the goal is an easy to hover 3D. All a tail heavy airplane wants to do is fly nose up. For normal flying that's very bad. Would you say you want the airplane to be neutrally balanced so it'll fly flat and prop hang? Too many 3D YouTube videos are boring because all the flier shows is an airplane hovering. I think practicing slow high-alpha will be useful for indoors in the winter.

 

[SlingShot]

Nice project! The paint also. Looks very commercially.

 

[TooJung2Die]

Flew the MPF Yak-55 several times today. What a difference. Just what I was hoping for. Very slow and floaty then it leaps when throttled up. I've never flown anything that rolled this quick. The "lighter the better" advice is spot on when it comes to 3D. Everyone at the RC field that was involved with the build got to see it fly. It came home with only grass stains on the belly. I was using 850 mAh 2S batteries that gave it an AUW of around 7.5 ounces. Someone asked if it'll fly on a smaller battery so I tried it with a little 450mAh 2S. It flew even better. The battery life was much shorter but now I know what to use when flying it indoors. I think I'll try an even smaller 350 mAh next time out.

If I'm going to build this again with Adams foam board it'll have to be single thickness with no paper. It will need CF spars in the wings and tail. The fuselage will need CF stiffeners to reduce twisting. It'll probably fly just as well as the MPF version but won't survive getting banged up very long.

 

[Chuppster]

I will. That sounds counter-intuitive and crazy but it makes sense if the goal is an easy to hover 3D. All a tail heavy airplane wants to do is fly nose up. For normal flying that's very bad. Would you say you want the airplane to be neutrally balanced so it'll fly flat and prop hang? Too many 3D YouTube videos are boring because all the flier shows is an airplane hovering. I think practicing slow high-alpha will be useful for indoors in the winter.

It's personal preference. A tiny bit aft cg and it shouldn't be too squirrely. If you can't trim it out straight and level it's defiantly tail heavy!

 

[TooJung2Die]

Since the double layer DTFB Yak now flies better than expected it deserves some decoration. It also needed something to help with orientation. It rained all day so a little quick-n-simple airbrush masking and stenciling made up for not flying. The DTFB will be the windy day 3D Yak. The MPF Yak will fly on calm days or indoors.

These airplanes are great for making you a better pilot. Because they are so cheap and easy to build it eliminates the fear factor of crashing. A good RC pilot at the airfield coached me through flying inverted for the first time. It flies inverted hands off, no elevator input needed. He never would've talked me into that with a balsa airplane that took months to build.

 

[Chuppster]

Since the double layer DTFB Yak now flies better than expected it deserves some decoration. It also needed something to help with orientation. It rained all day so a little quick-n-simple airbrush masking and stenciling made up for not flying. The DTFB will be the windy day 3D Yak. The MPF Yak will fly on calm days or indoors.

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These airplanes are great for making you a better pilot. Because they are so cheap and easy to build it eliminates the fear factor of crashing. A good RC pilot at the airfield coached me through flying inverted for the first time. It flies inverted hands off, no elevator input needed. He never would've talked me into that with a balsa airplane that took months to build.

Well, if it flies hands off inverted, that's what you want! Sounds like you've got it balanced pretty well, and it looks great to boot!

 

[TooJung2Die]

Well, if it flies hands off inverted, that's what you want! Sounds like you've got it balanced pretty well, and it looks great to boot!

Thanks! What I want now is to figure out how to turn off what my brain has been trained to do with the elevator. Trying as hard as I can I can't seem to get my fingers to move in the opposite direction when flying inverted. It is very frustrating. As soon as I attempt an inverted turn I screw it up. Anyone have some advice?!?

 

[Merv]

Great looking planes.
I wonder if 2 layers of FB are necessary. Would a single layer of paperless FB would work? How much weight would it save?

 

[Chuppster]

Thanks! What I want now is to figure out how to turn off what my brain has been trained to do with the elevator. Trying as hard as I can I can't seem to get my fingers to move in the opposite direction when flying inverted. It is very frustrating. As soon as I attempt an inverted turn I screw it up. Anyone have some advice?!?

Honestly, I find it easier to fly inverted when the airplane needs some up elevator. At some point my brain started being able to take an input and use feedback from it to make the right decision. So, if I'm controlling the pitch while inverted, and I'm pushing "up" on the stick to pull up, it's easier for me if I have constant pressure on the stick. It takes some time, but there was a point where I had been doing so much inverted on a flight that I rolled upright and tried to fly with "inverted" elevator. Thankfully it didn't take long for my brain to snap out of it.

In sort, muscle memory. You just gotta practice. And having it a little nose heavy so it's trimmed "nose down" inverted helped me fly inverted. It doesn't help me 3d, but it does help inverted.

 

[TooJung2Die]

I wonder if 2 layers of FB are necessary. Would a single layer of paperless FB would work? How much weight would it save?

Flyboa made one like that and it flew very well. There's a video of it on his YouTube channel. If I made another with DTFB it would be one layer, no paper. It'll need strategically placed carbon fiber to stiffen it up. It'll be fragile and not survive crashes or hard bumps but it'll be light. MPF is a lot like DTFB with the paper removed but stronger. EPP foam seems to be the material of choice for this type of airplane. It's very light and springs back from crushing and bending. It too needs carbon fiber stiffeners because it's floppy.

 

[TooJung2Die]

In sort, muscle memory. You just gotta practice.

I hear that. I think some simulator time is a good idea to retrain the brain. Then I can crash it endlessly.

 

[TooJung2Die]

I haven't gotten away from the 3D thread yet. Since all my flying during the winter is indoors I want a very light and durable airplane. I could probably fly the Yak made from MPF but I'd prefer something even lighter. I can't bring myself to build a third Yak in a row so I searched and found the "One Hit Wonder". I like the way it looks and the guy that designed it does a good job flying it.

"One Hit Wonder" 30 inch Dollar Tree Foam

Yes, he made it from Dollar Tree foam board; so one good hit and the airplane is wrecked. Instead of the usual DTFB I invested in a few sheets of EPP foam. This stuff is expensive compared to good old Dollar Tree FB but it doesn't break when bent. It takes a hit much better.

I'm about half-way through building it. Doing a four color paint job like this takes more patience than I have so the bottom came out one color.

Top side paint job.

Fuselage glued and control surfaces hinged.

Jon

 

[The Hangar]

That looks pretty sweet man!

 

[Mr. Gandalf]

Nice work, looks like It will be a great flyer!

 

[TooJung2Die]

Ready for flight if the weather cooperates. Weight without battery is 147 grams, about 5.2 ounces. Less than the Yak-55 made from MPF and weighing 6.5 ounces without battery. The One Hit Wonder has a Gartt 2204-1500kv motor with a 8x4 prop for the first flights.

Now I understand why Leadfeather made the tail of the Yak so wide. EPP foam is very floppy. The One Hit Wonder needs CF stiffening in the tail section when built from EPP. The One Hit Wonder is okay without support when made with Adam's FB or MPF.

Guess I did a pretty good job with the symmetry. Here it is balanced on the propeller hub.

Jon

 

[TooJung2Die]

Flight Report! The One Hit Wonder flies great. I flew it with a 350 mAh and 450 mAh 2S. With the throttle barely open it floats around like a slow flier. At 3/4 throttle it has unlimited vertical. Loops are so tight it looks like a back flip. It rolls like a drill. If you start the rolls with a nose up attitude you can roll it all day. Inverted flight is neutral; no down elevator needed.

On the fourth flight it started acting strange. The elevator servo locked up. It was a new servo but it was a little noisy from the start. Fortunately the servo froze with the elevator centered. I got it down unharmed and swapped batteries. The elevator worked again but soon locked up in the air. This time it hit the wing tip hard on landing and cart wheeled. There was a only a small crack in the EPP at the wing root. The wing is fixed and the servo replaced with a fresh one. I can't wait to try this out indoors at the hockey arena.