FT Flerken ***Official Thread***

[toryander]

That sound is a very thin and flimsy prop spinning at higher speeds than designed for and vibrating. I’ve never had anything bad happen from that (yet), but I suppose it’s likely that the vibration could break the prop itself, or unscrew the motor from the firewall. I’d get a better prop. The standard gray ones are better.

That makes sense. Thanks! I've ordered some 5 x 4 x 3 from Amazon (I think I saw somewhere on Flite Test that they used this prop). I wonder if they will be cheap and flimsy, too. I'm really looking forward to flying (not destroying) my Millennial Flerken.

 

[toryander]

It's ok to fly with them, they're just loud.

We'll see if I dare, today. I've never flown a wing. I have the aura board in there. It's been helpful but, for various reasons, that's never guaranteed me anything.

 

[Proptastic]

We'll see if I dare, today. I've never flown a wing. I have the aura board in there. It's been helpful but, for various reasons, that's never guaranteed me anything.

Blue skies. Let us know how it goes.

 

[toryander]

I maidened the Millennial Flerken, this morning (I swapped out the cheap orange prop for a not-as-cheap black 6 x 4.5). I just swallowed hard, revved her up, and gave her a wing toss. I cheated by using the aura launch assist (I'm not sorry) and it went up like a really fast bird. It was beautiful--took my breath away. I went around a few times in stabilize before turning the gyro off. I continued to fly it, but it was a bit nose heavy and leaned heavy to the left. I tried to trim it, but I'm not good enough to do that without crashing the plane while doing so and didn't get it done. I got it a little better before having to hit the panic switch back to stabilize. It almost flew away from me (many blocks). I'm not sure how I got it back, but I did. I only have hard earth to land on and it pulled the engine with firewall out the back, but no broken prop or anything. Just need to glue it back in. Maybe I'll land her over the fence in the hay next time . I can't wait to get her fixed up and back up in the air.

 

[Foamforce]

I maidened the Millennial Flerken, this morning (I swapped out the cheap orange prop for a not-as-cheap black 6 x 4.5). I just swallowed hard, revved her up, and gave her a wing toss. I cheated by using the aura launch assist (I'm not sorry) and it went up like a really fast bird. It was beautiful--took my breath away. I went around a few times in stabilize before turning the gyro off. I continued to fly it, but it was a bit nose heavy and leaned heavy to the left. I tried to trim it, but I'm not good enough to do that without crashing the plane while doing so and didn't get it done. I got it a little better before having to hit the panic switch back to stabilize. It almost flew away from me (many blocks). I'm not sure how I got it back, but I did. I only have hard earth to land on and it pulled the engine with firewall out the back, but no broken prop or anything. Just need to glue it back in. Maybe I'll land her over the fence in the hay next time . I can't wait to get her fixed up and back up in the air.

Congrats!! You could drop to a 3 blade prop, 1 inch smaller in diameter, and that would give you more ground clearance. That helped me. Congrats on getting it flying!

 

[toryander]

Congrats!! You could drop to a 3 blade prop, 1 inch smaller in diameter, and that would give you more ground clearance. That helped me. Congrats on getting it flying!

I just got some 5 x 4 x 3s in. I'll do that (and try landing in the hay over the fence )

 

[toryander]

I just got some 5 x 4 x 3s in. I'll do that (and try landing in the hay over the fence )

I put on the 5 x 4 x 3 (and landed in the weeds over the fence). Everything was fine. Yay!

 

[toryander]

I used the aura board's take off assist this morning and it was still a bit rough. Is this normal? (using a 3s 2200 mAh and a 5 x 4 x 3 prop. No wind, lots of wild fire smoke).

 

[Foamforce]

I used the aura board's take off assist this morning and it was still a bit rough. Is this normal? (using a 3s 2200 mAh and a 5 x 4 x 3 prop. No wind, lots of wild fire smoke).

Looks like just the throw. If your takeoff assist allows you to put the controller down, or if you have a friend to assist, the easiest throw that I’m aware of is backwards over your head. Get a hand at the front of the wing root on both sides and hold it straight out in front of you, tail down. Then throw it up and over your head behind you. This throw is easiest because it doesn’t cause any roll or yaw.

 

[toryander]

Looks like just the throw. If your takeoff assist allows you to put the controller down, or if you have a friend to assist, the easiest throw that I’m aware of is backwards over your head. Get a hand at the front of the wing root on both sides and hold it straight out in front of you, tail down. Then throw it up and over your head behind you. This throw is easiest because it doesn’t cause any roll or yaw.

Thanks. I'll be more careful on the throw. when I have a second person, I'll try the backwards launch.

 

[toryander]

I've flown the Flerken twice successfully and had a great time. I love how it looks zooming by. I took it out this morning looking for another great flight. I did all the checks including gyro and cog. I revved it and gave it a calculated wing toss. It went straight up and came straight down. I checked everything, and then tried again with the same result. Gyro isn't loose (with same config as on the two successful flights). Control surfaces are correct. It seems it has to be cog, right? Cog is tricky for me on the Flerken. You put your fingers in the middle of those little triangles at the forward wing roots to check (according to the video), but the plane is always falling backward or forward depending on the slightest motion of my fingers. Is it this tricky for everyone or am I doing something wrong? I'm guessing I erred on the side of tail heavy this morning. I thought I had it in the same place as yesterday when it flew well. I'll try again. I hope it's not too nose heavy next time as I move the battery forward. My other planes aren't this touchy.

 

[toryander]

Well, I got two flights out of the Millennial Flerken. Then, suddenly, she was tail heavy (crash). Then, she was nose heavy (lost in a hay field). Then, nose heavy again after a correction (lost high in a tree). After those first two successful flights I just couldn't get the cog right. I'm not sure what changed (I repaired, studied it, checked surfaces, checked cog according to videos). I'm disappointed. I loved the way it looked zooming through the air when it flew. Needs some more repair. Maybe I'll come back to it. I guess it was just too advanced a build for me. Still, life goes on.

 

[Foamforce]

Well, I got two flights out of the Millennial Flerken. Then, suddenly, she was tail heavy (crash). Then, she was nose heavy (lost in a hay field). Then, nose heavy again after a correction (lost high in a tree). After those first two successful flights I just couldn't get the cog right. I'm not sure what changed (I repaired, studied it, checked surfaces, checked cog according to videos). I'm disappointed. I loved the way it looked zooming through the air when it flew. Needs some more repair. Maybe I'll come back to it. I guess it was just too advanced a build for me. Still, life goes on.

Assuming that you didn’t make any big changes to your COG after your successful flight, I would guess the throw again. It’s pretty easy to throw at far too steep of an angle and then no amount of gyro or launch assist will save it.

Try this. Throw less hard. Do a relaxed throw that is almost flat, just a few degrees up. You probably have enough power that if you launch it fairly straight, it will start flying immediately. These have quite a bit of lift, so they don’t need a ton of speed to take off.

Since you’re launching by yourself, my favorite self launch method is to hold the left wing tip with my right hand. The plane will initially be vertical. Then with my right hand on the controller I have it about 80% throttle and get my hand onto the right stick. At the point the plane will be trying to fly out of my hand already. Give it a very light swing around your body and it will naturally start to rise. Release it when it gets to about 45 degrees from the ground. After you release it, it will continue to roll to the left, so if you wait until it’s level before releasing, it will roll all the way over to the left and crash. Releasing it at about 45 degrees means that it will level out close to flat.

Or get a friend or there and do the overhead throw until you’re very comfortable with flying it. Throwing a wing can be tricky at first and it helps if you’re completely confident with the plane first.

 

[toryander]

Assuming that you didn’t make any big changes to your COG after your successful flight, I would guess the throw again. It’s pretty easy to throw at far too steep of an angle and then no amount of gyro or launch assist will save it.

Try this. Throw less hard. Do a relaxed throw that is almost flat, just a few degrees up. You probably have enough power that if you launch it fairly straight, it will start flying immediately. These have quite a bit of lift, so they don’t need a ton of speed to take off.

Since you’re launching by yourself, my favorite self launch method is to hold the left wing tip with my right hand. The plane will initially be vertical. Then with my right hand on the controller I have it about 80% throttle and get my hand onto the right stick. At the point the plane will be trying to fly out of my hand already. Give it a very light swing around your body and it will naturally start to rise. Release it when it gets to about 45 degrees from the ground. After you release it, it will continue to roll to the left, so if you wait until it’s level before releasing, it will roll all the way over to the left and crash. Releasing it at about 45 degrees means that it will level out close to flat.

Or get a friend or there and do the overhead throw until you’re very comfortable with flying it. Throwing a wing can be tricky at first and it helps if you’re completely confident with the plane first.

Thanks, Foamforce. I think I have the wing throw down pretty good. On both nose heavy flights it flew a long ways, but I couldn't gain altitude and get it back around to me. After the first throw I retrieved it (a pretty good walk and search), moved the battery back a bit, and checked the COG (those little marks in the triangles at the wing roots. It seemed to be level, slightly down like I'm told. The next flight, same thing. Good throw, plenty of power. The plane (in stabilize) just couldn't gain altitude and then had a relationship with my neighbor's tree. I started to see that the cog marks (on mine) are in the wrong place. From its nose heavy behavior I have to guess that the cog to be farther back by the leading edge. I adjusted for that, but the next throw I forgot to turn on Stabilize (I think that was the problem) and my Flerken did a crazy little dance before diving the ground in a cloud of dust. I don't know if it was structural or just a jerky takeoff. Now the engine mount is broken again. I enjoyed building it and those first two flights were amazing, but I'll give it some time, now. Do you have videos of you flying yours? I'd love to see.

 

[Foamforce]

I don’t think I have any videos but I’ll try to remember to take some next time I’m out.

Regarding yours, do you have the required amount of reflex in your elevons? It’s possible that if you don’t have enough reflex, then you (or the gyro) had to compensate by pulling up, and there may not be enough extra throw to get the nose up.

Another possibility is that if your gyro is in full Angle (Safe) mode, that may have reduced your throw so much that when you launched without it, you may have severely over-controlled it. Sorry if this is too elementary of advice, I’m not sure what your level of expertise is!

 

[toryander]

I don’t think I have any videos but I’ll try to remember to take some next time I’m out.

Regarding yours, do you have the required amount of reflex in your elevons? It’s possible that if you don’t have enough reflex, then you (or the gyro) had to compensate by pulling up, and there may not be enough extra throw to get the nose up.

Another possibility is that if your gyro is in full Angle (Safe) mode, that may have reduced your throw so much that when you launched without it, you may have severely over-controlled it. Sorry if this is too elementary of advice, I’m not sure what your level of expertise is!

I appreciate your insights. I think your comments are on the mark. When I built it I noticed that my servo control arms were way lower than Josh's in the video even though I had used the correct arms (I tripled checked). I had to create a channel for the control rods not to hit the foam board near the servo. I can see that there needs to be more throw. But that is one of the difficulties of the Flerken--you don't have access to the servos after making the wing. However, the thing that throws all the confusion into the troubleshooting reasoning is that it flew perfectly on Aura the first two flights. I had full control both on Stabilize and then no gyro. It flew high, it flew low, it did aileron rolls. It was great (I loved it). No crashes. Then the third flight it went straight up and back down (tail heavy?). Minor repairs. Then 4th and 5th flights it flew smoothly, but couldn't gain altitude (nose heavy?). So something changed (where I put the battery is all I could think of). I'll repair it one more time, but I don't have a lot of hope since, if it's a cog problem, their dots seem to be off on my build. If it's also a throw problem (and it does need more throw) I can't access the servos to correct that. I'm sure it all stems from my limited build experience (I've built a couple of Explorers (I love them), a Tutor (it flies great), and the P-38 Flat Flyer (not a good experience), but I definitely don't have that "builder's touch" that some of you do. Anyway, I apologize for the long response. I'm mentally cataloging your comments for future experience. Thanks!

 

[toryander]

I finally got past my frustration and repaired the Flerken one last time. Mainly, it was putting the firewall back together again. I put the battery and guessed at the COG (a quarter inch back from the dots just by the leading edge). My Flerken is pretty beat up and I fully expected another crash, but, to my surprise, she flew. I have to fly her on Stabilize because she rolls hard to the right, otherwise (even on full trim), but I still had a great time. I had three good flights although the landings on hard ground (all that's available) is rough on her. On the first flight she nearly crashed when the bottom, back fuselage cover tore off. She became nose heaving and headed for Earth, but I was able to recover her for more flights. The Flerken is so much fun.

 

[Foamforce]

Well, the problem wasn’t your throws, those looked great!

I’d be really curious to know what your issue was if you ever find out!

 

[toryander]

Well, the problem wasn’t your throws, those looked great!

I’d be really curious to know what your issue was if you ever find out!

It ended being what I thought it was--bad cog. I know enough to check cog and get the plane balanced with maybe nose down ever so slightly, but when I did it using the cog holes on the Flerken it flew nose heavy. After those nose heavy crashes I guessed that the cog was closer to the leading edge of the wing and set it there. That did the trick. Yes, the wing toss is working great. I don't hardly need to toss it as it tries to fly right out of my hand. It's so much fun. Now, if I can just get it trimmed (it's way out of wack) so I can fly it on acro.

 

[bisco]

success!