Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[flyAA]

I have 39 flights on mine and am using steps 1-3 and 5. :-) The only issue I have had was during testing of the flap down during a high speed pass scenario. It only happened once but is very spooky. Luckily I was testing and was up high enough and ready to pull throttle. It happened so fast I wasn't sure if it just wasn't my imagination.
I have a voice notification on my radio to tell me if my throttle is above mid power with flaps deployed.
So....
6. Some sort of alert or mix to disable flaps with high throttle setting or gear up is important with this model too. It is easy to forget flaps. I used to do it all the time until I configured my radio to 'remind me' that I was doing something stupid.

Make sure you know to about the falling leaf situation and how to recover. I have seen that a lot but I am stalling it a lot doing flips and 'almost' cobra maneuvers. Kill throttle and dive...

Good stuff! I’ve definitely left the flaps down unintentionally before so i will def set up an alarm. Wonder if my dx8 has that capability, hmmm.

[bandetx]

You probably don't want to mix throttle to flap.

Because the issue isn't flap+throttle it's high speed+flap. Being high throttle doesn't necessarily mean high speed... imagine coming in for landing and needing a go-around and you punch the throttle and your flaps go up, or your flaps go up on takeoff instead of saying in takeoff mode.

[Nickc2023]

Which might very well be perfectly fine :D

The mount of nose heaviness these models are designed around is no longer just silly and sad, but outright dangerous.

I love flying but to be honest I don't know too much about what goes into designing these aircraft. Why would a manufacturer choose to make the jet soooo nose heavy?

[Nickc2023]

Just the fact that they put a battery strap in the front bay is starting to seem ridiculous. They should have called it a reciever bay instead. I think the only reason mine balances ok is I put my rx next to the blue box, added the centerburner leds and have a 2s 800mah behind the cg point.

[HaroldAnderson]

You probably don't want to mix throttle to flap.

Because the issue isn't flap+throttle it's high speed+flap. Being high throttle doesn't necessarily mean high speed... imagine coming in for landing and needing a go-around and you punch the throttle and your flaps go up, or your flaps go up on takeoff instead of saying in takeoff mode.

Good point. Some guys are using gear and flaps that would be a lot better than the throttle if your radio doesn't have a way to alarm you.


flyAA,

I forgot the mention the CG thing too. Most of us are flying them 10mm behind the factory CG.

[HK111]

Just the fact that they put a battery strap in the front bay is starting to seem ridiculous.

Actually, no. In my 12S setup with very light batteries, the forward battery has to go into the front bay in order for it to balance at about 160mm.

[Reaper911]

Actually, no. In my 12S setup with very light batteries, the forward battery has to go into the front bay in order for it to balance at about 160mm.

man that thing must rock on 12s

[themudduck]

Hey, nice discussion. "don't use landing flaps at high speed". Hmm. Why would anyone DO that? I only use full flaps on final approach, after the model has begun to slow down.

Some other things that aren't particularly wise to do with RC planes:

• don't turn off the transmitter if the plane is still turned on (or while its flying)
• don't look down to check your phone/zipper/transmitter while flying
• don't fly over the pits, or over football games, airports, etc.

Now, yes I can certainly appreciate that the "FFS" (stabs) are deforming due to loads in high speed dives with the flaps down. Maybe overloading the servos as well. That video was incredible. I'm not saying that isn't a thing - but it's not the problem that some of us have reported. Both elevators simply stopped working while I was flying at low speed, low throttle, flaps up, and simply losing altitude gliding in a level slight dive towards the end of a completely normal low-drama flight. Function returned after about 2 seconds when I cut the power, and then I returned to flying normally and landed (with flaps) without any issue. (I also have balanced stabs, the upgraded servos, and HD hardware)

Others here reported the same thing: the servos simply stopped working while flying normally. So we've figured out we shouldn't dive at 120mph with flaps out. But why are the servos shutting off in flight for no apparent reason? As opposed to a failure when under a large load, having both servos cut off during normal flight doesn't seem to have anything to do with the airframe. So I think there may be more than one problem here.

[RCjetdude]

Finally started working on a drag chute release for this bird. Aside from a few springs, a servo and hinge pin it should be completely 3D printed.

[kallend]

. But why are the servos shutting off in flight for no apparent reason? As opposed to a failure when under a large load, having both servos cut off during normal flight doesn't seem to have anything to do with the airframe. So I think there may be more than one problem here.

If the design of the airframe results in excessive loads being demanded of the servos even in level flight, that can easily lead to the kind of problem you observed.

And as has been amply demonstrated, the design of the airframe DOES demand unusually high loads from the servos.

[skybolt]

Has anyone checked their upgrade servos for travel as opposed to the stock ones? One of the upgrade servos I had in the kit was faulty as stated in my previous post this was replaced by MotionRC. EU. I have found that the stock servos have a limited travel the upgrade servos can travel 360% is this normal? I have never come across this in any other make of servo I have used.

[RedAlert]

I finally maidened my Mig today. Had 4 awesome flights. We had a nice 18C (64F) degree sunny day here in Canada today. Everybody came out!
What a fantastic jet! Wide flying envelope, rock solid, looks awesome in the air, slows down to a crawl and lands like a glider. I did some modifications to offload some of the stress from the elevators/FFS, and to accommodate for my heavy batteries (Admiral Carbon 5100mah 70C and Turnigy Graphene 65C) ~870g

Things I had done to my Mig:

- Upgraded elevator servos to Promodeler DS150CLHV
- Beefed up elevator rod, by inserting a PTFE tube inside the carbon tube, to fill the empty space
- CG 10-15mm aft of CG marks
- Flap/Aileron reflex (around 3mm)
- Removed 50-60g (at least) worth of unnecessary wires, moved the blue box all the way aft of the canopy bay.
- YEP 20A BEC. It comes with 2 output wires. Ran 1 wire into the RX and another into blue box. Should supply ample current where needed.
- Shortened the elevator extension wires (kept them the same gauge though). Tested the torque, by holding the elevator with my hand and moving the elevator control stick (on 5.1V). It moved the elevator and started bending the aluminum hinges, while the voltage stayed at 5.1. Very strong servos, even on 5V.
- Reduced mechanical travel on most control surfaces. Book suggestions results in excessive surface travel, and requires reducing the throws in the radio, which is far from ideal. Rudder and flaps definitely needed to go into more inner holes of the servo arms.
- Installed afterburners to help with CG

The jet was very stable in the air. I don't know if that's because the Promodeler servos center very well and are pretty tight (no deadband movement), or it's just the model's design, but I was very pleased with it's performance.
Can't wait to fly it again!

[bandetx]

Hey, nice discussion. "don't use landing flaps at high speed". Hmm. Why would anyone DO that? I only use full flaps on final approach, after the model has begun to slow down.

Some other things that aren't particularly wise to do with RC planes:

• don't turn off the transmitter if the plane is still turned on (or while its flying)
• don't look down to check your phone/zipper/transmitter while flying
• don't fly over the pits, or over football games, airports, etc.

Now, yes I can certainly appreciate that the "FFS" (stabs) are deforming due to loads in high speed dives with the flaps down. Maybe overloading the servos as well. That video was incredible. I'm not saying that isn't a thing - but it's not the problem that some of us have reported. Both elevators simply stopped working while I was flying at low speed, low throttle, flaps up, and simply losing altitude gliding in a level slight dive towards the end of a completely normal low-drama flight. Function returned after about 2 seconds when I cut the power, and then I returned to flying normally and landed (with flaps) without any issue. (I also have balanced stabs, the upgraded servos, and HD hardware)

Others here reported the same thing: the servos simply stopped working while flying normally. So we've figured out we shouldn't dive at 120mph with flaps out. But why are the servos shutting off in flight for no apparent reason? As opposed to a failure when under a large load, having both servos cut off during normal flight doesn't seem to have anything to do with the airframe. So I think there may be more than one problem here.

Servos aren't shutting off in flight. The deformation of the stabs is likely doing something to "lock" the pivot in place so the servos can't articulate them.

[janmb]

I love flying but to be honest I don't know too much about what goes into designing these aircraft. Why would a manufacturer choose to make the jet soooo nose heavy?

Because of a misguided idea that this is necessary for the average/less skilled pilots to be able to safely operate the model.

Which is to some extent true, they just overdo it - massively

[kallend]

Servos aren't shutting off in flight. .

How do you know this?

[xviper]

my heavy batteries (Admiral Carbon 5100mah 70C and Turnigy Graphene 65C) ~870g

Things I had done to my Mig:
- CG 10-15mm aft of CG marks
- Removed 50-60g (at least) worth of unnecessary wires, moved the blue box all the way aft of the canopy bay.
- Installed afterburners to help with CG

The jet was very stable in the air. I don't know if that's because the Promodeler servos center very well and are pretty tight (no deadband movement), or it's just the model's design, but I was very pleased with it's performance.
Can't wait to fly it again!

Besides being able to put the top battery where the blue box was, do you think that it's the afterburner's weight that allowed you to balance this plane using those batteries? Those are quite heavy. I use the Gens Ace, which weighs in around the low 700's and I'm able to balance at 10mm aft of the marks. I'd like to use some of my heavier batteries but I doubt I'll be able to make it balance right. I will be getting the VT nozzles when they are available, hoping they will help with the balance when using heavier batteries and also to help out when and if my elevators don't do the trick in certain circumstances.
Like you, I've enjoyed great flights with mine, without any indication that something might go wrong. Of course, I've only had 6 flights in total and with winter's return, it's not likely I'll fly it again till spring. -2C here and just got back from flying my snow blower.

[bandetx]

TV nozzles will be good because they will add some redundancy for if the elevators fail.. You just have to leave them on 100% of the time!

[xviper]

TV nozzles will be good because they will add some redundancy for if the elevators fail.. You just have to leave them on 100% of the time!

All of my planes that have VT, the nozzles are active at all times. You just learn to fly the plane that way. They augment pitch, roll and yaw, so you use lower rates most of the time and then throw into high rates as airspeed dictates more need for them. In the case of this MiG, I'll do the opposite and use high rates most of the time, since it's not clearly known why the elevators sometimes don't do what they're supposed to.

[RedAlert]

Besides being able to put the top battery where the blue box was, do you think that it's the afterburner's weight that allowed you to balance this plane using those batteries? Those are quite heavy. I use the Gens Ace, which weighs in around the low 700's and I'm able to balance at 10mm aft of the marks. I'd like to use some of my heavier batteries but I doubt I'll be able to make it balance right. I will be getting the VT nozzles when they are available, hoping they will help with the balance when using heavier batteries and also to help out when and if my elevators don't do the trick in certain circumstances.
Like you, I've enjoyed great flights with mine, without any indication that something might go wrong. Of course, I've only had 6 flights in total and with winter's return, it's not likely I'll fly it again till spring. -2C here and just got back from flying my snow blower.

The way I see it only one of the batteries has a significant impact on CG, the aft battery is located almost at CG. My elevator servos are around 28g each, afterburners added another I believe 50g (and quite far back). Removing a lot of the wiring in the front, was another 50g or so. Moving the BB and RX all the way back helped as well. All of these combined, helped. And because I removed dead wiring, I wouldn't mind adding an ounce of led in the tail if I needed it to achieve good CG. I didn't add any led though. TV unit will certainly help with moving CG aft as well

[xviper]

The way I see it only one of the batteries has a significant impact on CG, the aft battery is located almost at CG. My elevator servos are around 28g each, afterburners added another I believe 50g (and quite far back). Removing a lot of the wiring in the front, was another 50g or so. Moving the BB and RX all the way back helped as well. All of these combined, helped. And because I removed dead wiring, I wouldn't mind adding an ounce of led in the tail if I needed it to achieve good CG. I didn't add any led though. TV unit will certainly help with moving CG aft as well

Good to know. I also have center burners coming.