Official Freewing 80mm MiG-21 Fishbed Thread

[Alpha]

Hi Flyinhigh042, would you be able to post a picture showing where you're measuring your CG from? We designed the MiG-21 to have a fairly wide CG envelope. I fly it more tail-heavy than usual for slower high alpha passes, while most fly the book's CG. The plane should feel "locked in" regardless as long as it's moving forward. Check that your surface neutral positions are level, too.

[TiredIronGRB]

What rates are you using?

[DCORSAIR]

What rates are you using?

That's what I was thinking, sounds like maybe between the CG not right and to much throw on the ailerons you were headed for disaster. You said something about the takeoff roll was long? Are you on grass or pavement? I fly from pavement and it takes off in a very short roll out, did you calibrate the ESC?

Just some thoughts for you is all because this Mig is so easy to fly and is very stable, hope you figure it out because it's a blast to fly.:Cool:

[flyinhigh042]

Thanks for the reply’s. I want to say I know the issue is just a set up error on my part. I just want to get to the bottom of it before attempting flight #2. The maiden flights on my L-39 and F-15 went so well, it could be I was a little complacent setting this one up.

Alpha: I measured from the point where the wing leading edge meets the fuselage. After the first flight I re-checked the CG position and found it to be slightly forward of the recommended range, about 10.2”. I have now moved the battery aft to achieve the 10.5” specified in the manual. But it sounds to me like I can move it slightly aft from there given previous comments. I took a pic of my battery (Admiral 6s 5000) position at 10.5”. It’s well back in the battery compartment.

TiredIron: I set the control throws both high and low per the manual. -35% expo high, -25% expo low. (Futaba) First flight was on high rates the whole time.

DCorsair: I fly off paved runways. It was in fact a long roll. At least compared to the MiG-21 videos I have watched. The ESC, fan and motor were “borrowed” from my L-39. The combo has been previously calibrated and been a great performer.

Pic 1 - CG measure point
Pic 2 - CG location, 10.5”
Pic 3 - Battery location, 10.5” CG
Pic 4 - CG location, maiden flight 10.2”

[DCORSAIR]

Thanks for the reply’s. I want to say I know the issue is just a set up error on my part. I just want to get to the bottom of it before attempting flight #2. The maiden flights on my L-39 and F-15 went so well, it could be I was a little complacent setting this one up.

Alpha: I measured from the point where the wing leading edge meets the fuselage. After the first flight I re-checked the CG position and found it to be slightly forward of the recommended range, about 10.2”. I have now moved the battery aft to achieve the 10.5” specified in the manual. But it sounds to me like I can move it slightly aft from there given previous comments. I took a pic of my battery (Admiral 6s 5000) position at 10.5”. It’s well back in the battery compartment.

TiredIron: I set the control throws both high and low per the manual. -35% expo high, -25% expo low. (Futaba) First flight was on high rates the whole time.

DCorsair: I fly off paved runways. It was in fact a long roll. At least compared to the MiG-21 videos I have watched. The ESC, fan and motor were “borrowed” from my L-39. The combo has been previously calibrated and been a great performer.

Pic 1 - CG measure point
Pic 2 - CG location, maiden flight 10.2”
Pic 3 - Battery location, 10.5” CG
Pic 4 - CG location, 10.5”

Wow, you did a great job on those pics. Well, I don't have any idea why you had trouble or a unstable condition, your setup looks just like where my CG is exactly and your battery is close to where I have mine, mine is stock and I can pull a very steep takeoff, not quite vertical but close to it, it won't keep going but I'm happy with the stock unit myself. Hope you find the problem.

[tengarang]

Thanks for the reply’s. I want to say I know the issue is just a set up error on my part. I just want to get to the bottom of it before attempting flight #2. The maiden flights on my L-39 and F-15 went so well, it could be I was a little complacent setting this one up.

Alpha: I measured from the point where the wing leading edge meets the fuselage. After the first flight I re-checked the CG position and found it to be slightly forward of the recommended range, about 10.2”. I have now moved the battery aft to achieve the 10.5” specified in the manual. But it sounds to me like I can move it slightly aft from there given previous comments. I took a pic of my battery (Admiral 6s 5000) position at 10.5”. It’s well back in the battery compartment.

TiredIron: I set the control throws both high and low per the manual. -35% expo high, -25% expo low. (Futaba) First flight was on high rates the whole time.

DCorsair: I fly off paved runways. It was in fact a long roll. At least compared to the MiG-21 videos I have watched. The ESC, fan and motor were “borrowed” from my L-39. The combo has been previously calibrated and been a great performer.

Pic 1 - CG measure point
Pic 2 - CG location, maiden flight 10.2”
Pic 3 - Battery location, 10.5” CG
Pic 4 - CG location, 10.5”

Looks like your CG is not the issue.

I think its your dual rate settings because if you followed the manual it calls out for 80% dual rates on the Ailerons
and 100% dual rates for the elevator. This is way too high with the stock servos which i assume you are operating with.

I dont use stabilizers or gyro on my mig as it doesn't need it at all.

i have my aileron rates set to 40% dual rates, high expo 40% medium expo 45% low expo 55%

for the elevator dual rates i have mine set to 50% with the same high to low expo settings.

This will fix your problem.

good luck on your second flight

[DCORSAIR]

Looks like your CG is not the issue.

I think its your dual rate settings because if you followed the manual it calls out for 80% dual rates on the Ailerons
and 100% dual rates for the elevator. This is way too high with the stock servos which i assume you are operating with.

I dont use stabilizers or gyro on my mig as it doesn't need it at all.

i have my aileron rates set to 40% dual rates, high expo 40% medium expo 45% low expo 55%

for the elevator dual rates i have mine set to 50% with the same high to low expo settings.

This will fix your problem.

good luck on your second flight

Your right, I didn't see what rates he was running, missed that in his post, no gyro on mine either, I just moved my servo horn linkages in two holes towards the servo on the ailerons and the elevators only, that slows the controls down, I don't use dual rates or expo and it flies so well for me, but yeah maybe over correcting was the issue on his.

[flyinhigh042]

Thanks everybody. I have moved the CG aft slightly to about 10.6”. Probably more important, I have toned down the aileron throws. This is my first delta wing. I was unaware they have a tendency to be more sensitive to ailerons. Correct? I fly my L-39 and F-15 at all times on the recommended high rates, and I like them there. But it seems the MiG is a different animal.

I still feel like the MiG rolled inverted during the maiden while the sticks were neutral. But that may not actually be the case. I could have been chasing my tail the whole time and didn’t realize I was over controlling. It was a very nerve racking 2 minutes.

I’m planning on a re-maiden hopefully one evening this week. I’ll report back. Thanks to everyone for the input.

[flyinhigh042]

Thanks to everyone for helping me get the Mig-21 dialed in. I set the aileron rates way back. Closer to half of what’s listed in the manual. I also moved the CG just slightly aft of the recommended position. I put 3 flights on it tonight. All 3 were a blast! This is a sweet jet. Not to mention how cool Gooniac’s afterburner looked in the evening light!

I should have done more reading and research before throwing the Mig together and going for it.

Final note. This is an awesome jet. For anyone who has followed along with my first post until now, the Mig is really great. Nothing to be scared of. In fact, I even find it easier to land compared to my L-39 and F-15. (Both also awesome jets)

[tengarang]

Thanks to everyone for helping me get the Mig-21 dialed in. I set the aileron rates way back. Closer to half of what’s listed in the manual. I also moved the CG just slightly aft of the recommended position. I put 3 flights on it tonight. All 3 were a blast! This is a sweet jet. Not to mention how cool Gooniac’s afterburner looked in the evening light!

I should have done more reading and research before throwing the Mig together and going for it.

Final note. This is an awesome jet. For anyone who has followed along with my first post until now, the Mig is really great. Nothing to be scared of. In fact, I even find it easier to land compared to my L-39 and F-15. (Both also awesome jets)

Congrats to all three successful attempts, this is the only EDF in the large scale quadrant i own for the reasons you have just said, i am a warbird guy by default and still enjoy this jet from time to time.

[gooniac33]

Thanks to everyone for helping me get the Mig-21 dialed in. I set the aileron rates way back. Closer to half of what’s listed in the manual. I also moved the CG just slightly aft of the recommended position. I put 3 flights on it tonight. All 3 were a blast! This is a sweet jet. Not to mention how cool Gooniac’s afterburner looked in the evening light!

I should have done more reading and research before throwing the Mig together and going for it.

Final note. This is an awesome jet. For anyone who has followed along with my first post until now, the Mig is really great. Nothing to be scared of. In fact, I even find it easier to land compared to my L-39 and F-15. (Both also awesome jets)

It is so much fun! I am really glad that you got it going and that you like the burner as well! Can't wait to see pix and video if you can get any!

[tengarang]

Looks like The Lightburner has come out with some new innovations Exclusive to The Lightburner. Safety features are added and the
Prices are very competitive and customization possible upon request.

I may end up getting the FW F-22 just to try out one of these new 90mm releases, Dual LED afterburner specifically designed for all dual tailpipe 80-90mm EDF models

[cashmoneybrother]

Wow! I had the same experience. My mig has been in the air 3 times and it was down right scary. I purchased a gyro but have yet to intall it. All setting are by the book so I'm definitely going to dial everything down. Thanks for the info. Hopefully i can dial this bird in.. Couse she sure looks pretty in the air and sounds even better!

[cashmoneybrother]

https://youtu.be/Rt6xWaTPIic

[cashmoneybrother]

Here she is covered in aluminum https://youtu.be/Rt6xWaTPIic

[DCORSAIR]

g

Wow! I had the same experience. My mig has been in the air 3 times and it was down right scary. I purchased a gyro but have yet to intall it. All setting are by the book so I'm definitely going to dial everything down. Thanks for the info. Hopefully i can dial this bird in.. Couse she sure looks pretty in the air and sounds even better!

Your jet looks awesome by the way and you just need to dial it down and put more flights on it every chance you get and you will get the hang of how it flies, it is different in some ways compared to other jets I have flown, first thing I do on all my jets is move the linkages in one or two holes on the servo horn side, this always helps maiden flights go well and not so scary, I fly with no expo or dual rates anyway so this is how I soften the controls, the Mig is easy to over control it, when I first got one I thought, I don't know about this one but after figuring out how it likes to fly, it is now one of my favorites, landing in the wind is hilarious, it just hangs there waiting for you to lower the throttle and settle it down in a nice AOA landing. Mine is stock, no gyro and it will go vertical on take off and loop over the top headed the opposite way in no time, fun jet, I'm not a big Mig fan but this one turned out to be so much fun to fly I decided to keep it..........:)

[cashmoneybrother]

Thanks for the advice.. I really do look forward to flying it. All the YouTube videos make this jet look like an absolute blast to fly!!!

[tengarang]

Thanks for the advice.. I really do look forward to flying it. All the YouTube videos make this jet look like an absolute blast to fly!!!

For the mig all you got to do is take the factor settings and divide by 2 and generally apply 45% expo to all control surfaces....and call that your high rate, and set your other rates from there at your discretion. no gyro needed just keep it simple

[cashmoneybrother]

Man! No wonder it's so sensative. I guess on the Mig a little goes a long way. Thank you for the advise i will definitely put it to use. Like I said i really like the way it sounds its much louder than my f86 or even an Avanti. Plus with the aluminum covering, it down right sparkles in the air. Thanks again

[gooniac33]

Man! No wonder it's so sensative. I guess on the Mig a little goes a long way. Thank you for the advise i will definitely put it to use. Like I said i really like the way it sounds its much louder than my f86 or even an Avanti. Plus with the aluminum covering, it down right sparkles in the air. Thanks again

If you follow the manuals recommendations for the Mig-21 you will be in for a wild ride!! cut your throws to half of what they recommend and use expo to your liking. It also helps to use a little bit of a aileron to rudder mix to keep the rolls axial. It helped mine a ton by doing that!