Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[crxmanpat]

Yup, if the gap between the rod and the CF tube is eliminated, the stiffness of the tube will mitigate any bending. Even more so if you use concentric/nested CF tubes, or even shove 2 more control rod pieces to prevent the flex inside the tube.

When I nested my CF tubes, the OD of the smaller tube matches the ID of the stock tube. I also put some of the kit snot glue on the smaller tube so that it holds the larger tube in position over the control arm connector.

[RC Rich]

I wonder which is stronger, 4-40 titanium or CF rods?

[Evan D]

4-40!is a thread size. You probably are talking a turnbuckle which is very strong.

depending on the size of a carbon rod it could be as strong.

[RC Rich]

4-40!is a thread size. You probably are talking a turnbuckle which is very strong.

depending on the size of a carbon rod it could be as strong.

Yes, sorry, I meant the 4-40 turnbuckle. There was a discussion earlier about those two solutions for strengthening the elevator pushrods.

[janmb]

Maiden +1 in the books.

Filmed from the ground as well as partial onboard (unfortunately the runcam is not very fond of too much cold, so typically cuts out mid-flight as it gets cooled down).

No drama what so ever, so not too much to take away from it in terms of forensics (fortunately I guess)

But seriously... freewing needs to stop constructing their models for half the recommended battery weight.... The conservative CG recommendations (and tightly related; airframe / battery location design) is getting to the point of being both ridiculous and dangerous.

In my case, I flew with Gens Ace 5000 mah 45C, a fairly light 5000 pack, as far aft as possible in aft and mid locations without digging foam, AND added 30g lead as far back on the fuse as possible, and still it is nowhere near balancing. This translates to about 15-16 mm aft of the marks, and it still needs a fair bit more. My current guess is that the actual neutral point is somewhere around 25 mm aft from the marks, but obviously wouldn't jump right into that. But still, it is getting a bit silly that we can't fly on recommended battery packs without serious mods to get CG good.

Sure, I realize the need for a *bit* conservative CG. You don't want 1000 random pilots starting off with a truly neutral model. That would not go very well. But there is a difference between having a shave and cutting your own throat.

[hmarmaizmd717]

Just for your peace of mind, change to 4-40 turnbuckles.

hmarmaizmd717

[hmarmaizmd717]

Just asking, I balanced mine with batteries front and back. It was tooo nose heavy. Would you recommend moving

the front one to the middle Better balance???

hmarmaizmd717

[Evan D]

Of course. You want to be balanced no more nose heavy than the marks under the wings. Unless you have very light batteries you'll need to use the middle battery location. I'm very sure that many of the earlier crashes were because people didn't realize there are three battery locations and just used the front and rear ones.

[xviper]

Just asking, I balanced mine with batteries front and back. It was tooo nose heavy. Would you recommend moving

the front one to the middle Better balance???

hmarmaizmd717

The front battery tray is really NOT for a battery. I believe that's how the first 3 crashes in Taiwan happened. That and the likelihood that those guys didn't bother to read the manual and they used the first hole in the elevator servo arm with the original un-upgraded servos.

Oops, what Evan D said.

[janmb]

The front battery tray is really NOT for a battery. I believe that's how the first 3 crashes in Taiwan happened. That and the likelihood that those guys didn't bother to read the manual and they used the first hole in the elevator servo arm with the original un-upgraded servos.

Yup, the more nose heavy the model is, the more prone it necessarily will become to elevator issues.

[crxmanpat]

The front battery tray could be used if you're using very light batteries, like small 4000's. Anything bigger needs to go on the middle and rear battery positions.

[hmarmaizmd717]

I'm using 6000 bats.
hmarmaizmd717

[GliderGuy]

I'm using 6000 bats.
hmarmaizmd717

I am using the Admiral Pro 6000 batteries. Absolutely one in the middle and one in the rear. Do not put one in the front battery bay!

Set your timer to 3:30 to start with and then experiment with longer flights vs ending cell voltage that you want.

Expect you will need 4 mm of FFS trim vs the book 1 mm. If you maiden with the book 1 mm trim, you will quickly be adding more clicks of nose up trim. Maybe maiden at 3 mm to start with.

I reduce to about 30% power on down wind...full flaps and gear, then reduce to about 15% on final....and adjust power on finial as needed. She floats a lot, but so easy to land!

-GG

[janmb]

Expect you will need 4 mm of FFS trim vs the book 1 mm. If you maiden with the book 1 mm trim, you will quickly be adding more clicks of nose up trim. Maybe maiden at 3 mm to start with.

I would not dare fly this model that nose heavy in the first place. It is definitely asking for trouble.


My current trim: (still nose heavy)

[GliderGuy]

I would not dare fly this model that nose heavy in the first place. It is definitely asking for trouble.

All I can go by is 400+ flights on mine and no trouble. Not saying that this trim set-up works or will work for everyone.

-GG

[RudyD54]

I wonder if the reflex in your flaps changes your trim a little. 🤔 I got uncomfortably tail heavy (the tail was dropping on me and the jet felt like it would begin pitch up at anything less than half throttle) and I don’t believe I had that much down trim. Then again, I didn’t put any reflex into my flaps or ailerons. With my CG roughly 10mm back from the stock marks with the gear down I’ve got the leading edge of the elevator just about in line with bottom edge of the fuselage and it’s where I personally found it to fly comfortably and felt neutral.

I would not dare fly this model that nose heavy in the first place. It is definitely asking for trouble.


My current trim: (still nose heavy)

[leithalweapon]

The flaps.and ailerons are aft of the cg. Deflecting them upward pushes the tail down and the nose up.

[RudyD54]

Thanks for the info. That would make sense then. 👍

The flaps.and ailerons are aft of the cg. Deflecting them upward pushes the tail down and the nose up.

[janmb]

I wonder if the reflex in your flaps changes your trim a little. 🤔 I got uncomfortably tail heavy (the tail was dropping on me and the jet felt like it would begin pitch up at anything less than half throttle) and I don’t believe I had that much down trim. Then again, I didn’t put any reflex into my flaps or ailerons. With my CG roughly 10mm back from the stock marks with the gear down I’ve got the leading edge of the elevator just about in line with bottom edge of the fuselage and it’s where I personally found it to fly comfortably and felt neutral.

Yes, the slight flap reflex does indeed affect the elevator trim (positively)

I had no signs of the model wanting to sit on her butt, neither during turns or when slowing down. That would have been a good sign imo - a neutral or close to it model typically does.

I don't consider it a fault or drawback if a model hangs it's tail if you bank and yank though. A balanced model *should* do exactly that if you don't use your rudder. If a model tracks through a turn, having the nose seek into the turn during bank and yank, it is nose heavy.

There are far better ways of actually testing balance, but this too is a nice little tell to look for.

[fishface5]

Well In my opinion something is still wrong with this jet!. I just got back from flying it and it went down. I flew it last week and it did a little dive on its own but i was able to compensate and land it ok. I figured maybe i was flying it to fast and hard so today I went and flew it scale like and it did a dramatic dive and i was able to get it pulled out and it did it again and i could not save it.

I have the updated servos and the updated rods and links. Hopefully some one can get this figured out.