Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[mshagg]

No need to do that. Your YT vids are educational and interesting and show stuff I want to see. Plus, you don't seem to get all worked up if I don't subscribe or hit "like". I guess you're just content with the simple things in life.

Haha, just yanking your chain mate.

Anyways, here's a design that should make the front retract and housing pretty much tank-spec. Im not yet convinced it's needed but saw some folk on the Motion FB page reporting breakages in this area from tough landings.

https://www.thingiverse.com/thing:4629598

[Waconut]

Grey skies have cleared here in Oklahoma and I am charging 4 sets of batteries and will be going out to test in a couple of hours. That is unless I chicken out.

;-)

Anxiously awaiting the test report

[mshagg]

Taking mine out this afternoon but I'll leave the high speed dives with potential loss of pitch control to braver souls...

[xviper]

Taking mine out this afternoon but I'll leave the high speed dives with potential loss of pitch control to braver souls...

But you need to exercise those butt cheek muscles. Give 'er flaps when you do it.

[HaroldAnderson]

Anxiously awaiting the test report

Well, I don't have any conclusive results but I still have my plane.. Right after the warm up flight the wind came up at 17 gusting to 22 and the sky had turned grey again like it has been for about the last week. :-( The Mig is hard enough for me to see on a grey, cloudy sky that I was not comfortable getting it way up there. I made 3 more flights and made about 8-9 test runs from about 300-400 feet. On one faster more shallow pass with half flaps it did seem to lose elevator control for just a bit before I killed the throttle but that could have just been me. This testing is a little unnerving at those altitudes so I was probably diving for only 2-3 seconds, if that, before I needed to pull on the elevator. I will try again on a day with a clear blue sky that the Mig does not blend in so well with.

[xviper]

HaroldAnderson You are very brave to undertake this. Please be careful. I'm not sure we're worth it. If my flying season for this plane wasn't over, I'd do it just to see for myself. But even with what you got so far, there may be an answer looming close by.

[Colorc]

I gotta say that all the reported problems had me a little worried about getting my mig in the air and having fun, but i have a dozen flights on it and it has been an amazing performer for me. It sounds so amazing and just carries its energy very well. Landings are extremely smooth. Im running some heavier 4000 mah batteries.
From the get go I did a few of the mods suggested.
Elevators plugged directly into the receiver.
Added a little bit of reflex to the flap and aileron and cg back a little further than stock.
dubro safety links, ball links, and 4-40 rods for the elevator control rods.
I have the hitec d85mg but decided to give the replacement servos a try and havent had any problems. I will probably put the hitecs in during the off season.
After the first flight i already felt comfortable to add more throw to the rudder and elevators. After the third flight, i decided to go elevons and reduced the aileron throw by moving the aileron control horns two holes closer to the servo. I didnt feel like at any time that the stock upgraded servos were being over worked with taking on elevator and aileron duties. By the fourth flight i was doing high speed passes and it felt very locked in.
If you have some reservations about this plane, just send it. Its a great plane

[Colorc]

Something im curious about is what kind of receivers everyone is using. I know in the world of spektrum, that their receivers are rated to output a certain amount of power. I have always used a ar9020 on my bigger foamies that use multiple power hungry servos and keeping the y connectors to a minimum and never had weird glitches. I might be wrong, but maybe some of these smaller 6ch recievers are not fully capable of supplying the full power the servos need to function properly leading to problems

[mshagg]

Frsky here. Have one of the outputs from the CC BEC going into the Rx, the other into a spare port on the blue box.

[xviper]

Spektrum AR8010T.

[mshagg]

Double post

[nuts-n-volts]

If flaps were down in any of those cases, it would be interesting to know the draw on the servos at higher speed. I'm betting the stock bec couldn't take it and browned out the receiver. Also flaps being down will impart down to the plane unless compensation was set dead on. So, with stock bec, even if you run better servos and linkage on the elevator, I would double check amp draw with surfaces under pressure. The upgraded servos won't help here if the bec overloads. Better to run a higher amp bec and capacitor. YEP or Castle 20A should be fine. Ferrite rings are a good idea also.

[Flying Dutchman]

Then why didn't the ailerons also go down? They are in the same "plane" (the other plane) as the flaps and should have been subjected to the same forces. "No one does", at least not on purpose. I've done my fair share of flying around with take off flaps deployed because I forgot to suck them up, just like some people fly around with the gear hanging down the whole flight because they just didn't think to flip the switch and they don't even see them down (mental block). Oh well, we will never know for sure. The guessing continues.

He was definitely flying around with (full) flaps during his whole flight.

This is an enlarged screen shot at 2:55 minutes in his flight.

Could happen to all of us (at least I know it from myself) ;-)

Worthwhile to investigate further the effects of (full) flaps on a high speed dive!

[mshagg]

There's guys who have done it and guys who have lied about not doing it lol

[PieterO]

Something im curious about is what kind of receivers everyone is using. I know in the world of spektrum, that their receivers are rated to output a certain amount of power. I have always used a ar9020 on my bigger foamies that use multiple power hungry servos and keeping the y connectors to a minimum and never had weird glitches. I might be wrong, but maybe some of these smaller 6ch recievers are not fully capable of supplying the full power the servos need to function properly leading to problems

I use a Futaba R2008SB. No problems so far, but I've only done 10 flights with the Mig up to now. In my less expensive planes I use cheap Futaba clones, even Orange receivers. I haven't had a single RF issue with any of them.

[Parpoppet]

A few more thoughts on the Mig. I am wondering if we have two possible causes here. The original elevator servo not up to the job under certain flight loads, original pushrods inadequate and flexing, positioning of pushrod onto outer servo holes bearing in mind as I have been given to understand that every hole on the servo arm that you move out from the the first hole halves the rated torque for the servo.
With uprated servos, heavier gauge pushrods mounted in the second servo arm hole things start to look a whole lot better but, there’s always a but, could the problem of the plane suddenly diving also be caused by the plane being flown above a certain speed above a normal landing approach speed with flaps deployed there would be vortices coming off of the flaps. If these vortices were rotating in a downward motion they would hit the underside of the elevator leading edge and create a force pushing the elevator into a down position plus air will be hitting the elevator trailing edge upper side also causing pressure to force the elevator into a down position. All this creating a lot of extra load on the servos even with the above mods. Servo overloaded and stalled, pressure causing blowback. Could it be that what ever you do, do not lower the flats unless you are at landing approach speed or doing hi alpha speeds. I do think sometimes we do forget what sort of strain and pressures we put on our miniature aircraft airframes, I know I’ve been guilty of it in the past.

[GliderGuy]

Futaba receiver in my bird and 3 added ferrite RF filters and the green ring.

Using the stock UBEC which barely gets warm even if checked after multiple back to back flights. So it’s not working very hard IMO. And I have it hot glued to the foam, so one side only gets air flow for cooling. I may consider a remounting to improve cooling before summer comes. 8 amps is a good amount of muscle. UBEC wire extended...sits in the wing root by the rear battery.

About 500 flights no issues with flaps deployment at 1/2 throttle to slow for landing. Then gear down. Pretty much always. So lots of maneuvering at various speeds and attitudes with flaps down while in the pattern and setting up for landings. Flaps go down 30 mm every time.

Admiral 6000s / CG on the mark / Y bypass used with MRC upgraded servos / Du-Bro beefed up elevator rods and connectors / holes - throws are book other than flaps are a bit more than book / about 2 mm negative flaps / 3-4 mm of elevator trim

Flight style is a mix of 3/4 throttle cruise, full throttle passes and acro plus slowing to 1/2 throttle at the end for flap and gear deployment. 4:00 min / about 3.7 V post and typically 4000 mAh consumed.

25% power on down wind then 15% on final...so lots of speed/bank change-ups with flaps down. Gut feeling is....not an aerodynamic issue at least not with this set-up.

-GG

[kallend]

That's looking nice! And indeed much cheaper than the set I was planning to buy. But the set only contains one controller, right? So both burners will light up identically? I would like to have them flicker independently, to make it look less artificial.

My Arduino based Do-It-Yourself controller does exactly what you want and is FAR less expensive. If you know how to solder you can put one together in an evening and all the instructions are available on my blog:

https://www.rcgroups.com/forums/showthread.php?3313547-Make-your-own-EDF-afterburner

[kallend]

Futaba receiver in my bird and 3 added ferrite RF filters and the green ring.

Using the stock UBEC which barely gets warm even if checked after multiple back to back flights. So it’s not working very hard IMO. And I have it hot glued to the foam, so one side only gets air flow for cooling. I may consider a remounting to improve cooling before summer comes. 8 amps is a good amount of muscle. UBEC wire extended...sits in the wing root by the rear battery.

But are you flying around with flaps down (making the flap servos work hard) for an entire flight that includes several high speed passes?

[kallend]

I have been given to understand that every hole on the servo arm that you move out from the the first hole halves the rated torque for the servo.
.

That is incorrect. The torque is unchanged. The force it can provide reduces inversely as the distance of the hole from the servo output shaft.