Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[Griffon Wings]

Sausage fingers , sorry sorry ..
i mean a WHOLE year..

[xviper]

Just a personal note: With any plane that I plan to do extensive cosmetic mods, I fly it a few times first, THEN do the work. I'm not putting in that kind of time and effort only to smash the crap out of it when it doesn't fly right due to problems with me or the plane.

[radfordc]

I'm curious what happened. Did a bump pitch it up too suddenly, or something else? I'm wondering if this plane is just really risky on takeoff, because once the nose pitches up past a certain point, the stall will suddenly deepen into this kind of unrecoverable situation. I suppose any plane can stall on takeoff, but this plane might warrant more caution than most.

Anyway, I was just curious what learning you gleaned from this (assuming it was your plane). I was hoping to learn the same lesson a bit more cheaply :)

Two major errors occurred.... First, I saw the plane veer toward tall grass and pulled full up elevator before getting enough airspeed (should have aborted right there). Second, the nosewheel hit a bump and was bounced upward. Together, these caused the excessive pitch angle. Once the nose was up with very little airspeed the motor thrustline kept pushing the nose up. As the plane slowed a the peak of it's climb I realized it was about to pitch down and chopped power so as to not drive it into the ground harder than what was about happen anyway.

[radfordc]

Ouch....painful to watch!

Repaired OK? Hope so.

Perhaps keeping full power and Saber dancing to the ground might have been less of an impact. Hard to say.

-GG

Yes, repaired.

In retrospect I've considered whether keeping full power would have made the outcome better. My thoughts were that the plane would eventually stall and pitch down and power dive into the ground and that climbing higher would only make it worse;but on this one maybe not. I didn't have a lot of time to consider options.

[kallend]

Just a personal note: With any plane that I plan to do extensive cosmetic mods, I fly it a few times first, THEN do the work. I'm not putting in that kind of time and effort only to smash the crap out of it when it doesn't fly right due to problems with me or the plane.

Exactly my philosophy too.

(Except with Dynam planes that generally need a lot of work ahead of time).

[Griffon Wings]

Just a personal note: With any plane that I plan to do extensive cosmetic mods, I fly it a few times first, THEN do the work. I'm not putting in that kind of time and effort only to smash the crap out of it when it doesn't fly right due to problems with me or the plane.

Might be smart to do it , however , once I verify all servo works properly i usually start the paint job.
beside this one I always did so and everything works out very well on maiden ( F- 18/ AL-37/ A-4 / A-10 /Mig-21 ect ) .
if i may , in a positive note, i find painting this jet very easy, meaning, the paint job from factory was very well done . Nothing pilled out no where and this is a great plus , for me at list . I had lot of joy to work on this jet . I admit that . Alote .
beside the inconvenient, a great plane to work on it.
All good for the future 🛫🛫🛫

[xviper]

Yes, repaired.

In retrospect I've considered whether keeping full power would have made the outcome better. My thoughts were that the plane would eventually stall and pitch down and power dive into the ground and that climbing higher would only make it worse;but on this one maybe not. I didn't have a lot of time to consider options.

That repair looks great, like nothing happened. As far as the plane veering while on the ground run, consider an Assan steering gyro. They're quite cheap and will keep the plane straight as an arrow on the ground. I believe VT nozzles would have helped level the plane and get it going well enough to get airspeed up.

(Except with Dynam planes that generally need a lot of work ahead of time).

Well, we're talking Dynam planes here. Those should all come with a warning label, "DO NOT FLY OUT OF THE BOX". May as well "rebuild" first 'cause it'll be rebuilt soon enough after flying.

[GliderGuy]

Yes, repaired.

In retrospect I've considered whether keeping full power would have made the outcome better. My thoughts were that the plane would eventually stall and pitch down and power dive into the ground and that climbing higher would only make it worse;but on this one maybe not. I didn't have a lot of time to consider options.

From my experience and experimentation...once in high alpha lock with full power, I have not experienced anything other than a nose high, falling leaf, Saber dance behavior. Allowing this to impact might be reduced damage. BTW, your repair looks good!

Airguardian.....Comments?

-GG

[Airguardian]

On the aborted take-off?
I think as you do. With one addition. If the jet isn't still 'tail-sliding', adding full throttle will cause it to backflip, then it'd settle on the attitude you describe. So depending on the altitude, using full throttle at the wrong time could have cause the jet to smash nose-first into the ground.

So ideally, if one reached that point and had no TV, should let the jet begin to fall, then add full power, once it is no longer able to backflip entirely.
Easier said than done of course, requires good timing.

Back to the crash topic:

servos: i did pretty much the same of Brenden from Just plane Crazy , so Hitec servos , hangar 9 linkages. Very solid .

set up . Manual just like the manual.

This is very interesting because so far there were supposedly no reported crashes of the MiG with this failure-mode (sudden lawn darting without elevator response) with improved servos/linkages. I had insisted that I thought the problem to be elsewhere and many argued in reply that there was no evidence to back my claims... well, now there may be.

You had better servos and linkages and still the jet went down.

Also, were you using GOOD batteries?
If you were using old or bad-quality batteries there's a higher chance that you'd get a receiver brownout from BEC-battery combo not being able to cope with jet power demands.

And if you had stock set-up then your jet was extremely nose heavy and the stabs were over-taxed with non-reflexed wing airfoil.

The things that I did to mine that could be relevant:

- CG 15mm behind factory marks on the wings.
- Reflex trailing edge by 3mm flaps, 5mm ailerons (aprox).
- Reinforced stab assemblies to torsion (Epoxy - thick glass fiber laminate).
- Reinforced stabs to prevent deformation (WBPU - thin glass fiber laminate, 18g/m²).
- Replaced stab servos by Corona DS-238MG.
- Replaced stab linkages by 4-40 threaded rod with heavy duty Du-Bro ball links.
- Removed stock BEC.
- Installed separate 20A UBEC that runs from a standalone receiver battery (2S 610mAh).
- Installed ferrite chokes on ESC-Rx leads (next to ESC) and on the stab servo leads (next to servo).
- I am using the old FrSky Redundancy Bus for everything except landing gear, lights, and everything that goes through the ribbon cables (ailerons, flaps, gear doors), as these need to go through the BB.
- Shortened some of the wires, as I installed the RBus in the aft battery compartment.

Additional information that may be relevant to the topic:

Now that I've been flying the jet for a while I noticed a couple of times I got a 'power overload' warning while on the ground.
At the time I was not conducting logs so I cannot be more specific. Now I have enabled them so I will check what channels may be draining extra current.

Now that I have RBus telemetry I played a bit with the jet checking out the amp draw of the electrronics, and while it's bare 0.3-0.35 amps at idle, it could easily peak at 3A by just moving servos unloaded, and up to 5A by deploying LG and moving servos, also unloaded. With extra flight loads and possible further inefficiencies of particular set-ups, I could very easily see this reaching the nominal 8A current limit of the stock BEC (I think it was 8A?)... so there's that. I think that the stock BEC is under-sized for this jet, and should be run of a separate, dedicated receiver Li-Po pack, not the main packs for the EDFs. My 10 cents.

[radfordc]

That repair looks great, like nothing happened. As far as the plane veering while on the ground run, consider an Assan steering gyro. They're quite cheap and will keep the plane straight as an arrow on the ground.

Actually, mostly replaced rather than repaired. The reason for the plane veering left is that I forgot to lower flaps before starting the takeoff. It was dead calm and I quickly thought that flaps would be needed. I looked down at the Tx to flip the flap switch and that's when the plane yawed. I will look into a nosewheel gyro.

[Griffon Wings]

[QUOTE=Airguardian;n301113]On the aborted take-off?
I think as you do. With one addition. If the jet isn't still 'tail-sliding', adding full throttle will cause it to backflip, then it'd settle on the attitude you describe. So depending on the altitude, using full throttle at the wrong time could have cause the jet to smash nose-first into the ground.

So ideally, if one reached that point and had no TV, should let the jet begin to fall, then add full power, once it is no longer able to backflip entirely.
Easier said than done of course, requires good timing.

Back to the crash topic:



This is very interesting because so far there were supposedly no reported crashes of the MiG with this failure-mode (sudden lawn darting without elevator response) with improved servos/linkages. I had insisted that I thought the problem to be elsewhere and many argued in reply that there was no evidence to back my claims... well, now there may be.

You had better servos and linkages and still the jet went down.

Also, were you using GOOD batteries?
If you were using old or bad-quality batteries there's a higher chance that you'd get a receiver brownout from BEC-battery combo not being able to cope with jet power demands.

Hola Airguardian , yes i had 2 brand new batteries, Admiral 6000mah ..... i used before in the “ warm up “ flight on the al-37 , so they are just fine, yet 1 got lost on impact , can’t find it at all and the other is damage for good . On top the plane lost the new batteries aswell, darn it .
The CG , i find a sweet spot , infact , i did give it 2-3 click for triming on elevator as soon took off and was good .
botton line, if servo are good, linkages are good , reciver still working fine , what else can be ?
the only tail servo left in the plane i did cycle it for 5 full minutes at home . No problems, no hot , just fine .

Question is : why dove down so hard all together on a horizontal pass mid/up throttle?
and why i didn’t have elevator control anymore ?


wish to find the blubox, i’ll be back Saturday at the field to see if anyone find something ( we have a lost and found corner ) or i will look for it aswell , just to send to motion and maybe do a diagnostic of it .

Just for cause, not aspecting nothing from then ,even if the blubox have problems.

cheers

[GliderGuy]

Hi Griffon Wings....

Please confirm that you did not have add-on RF choke filters installed. It does not appear that you added RF filtering via ferrite chokes.

This is a well discussed topic in this forum. No guarantees, but they can’t hurt, and might actually prevent loss of control like this.

Thanks,
-GG

[Airguardian]

Took quite a while but managed to 'reconvert' my video to new music and re-upload, so there ya go! :)

Question is : why dove down so hard all together on a horizontal pass mid/up throttle?
and why i didn’t have elevator control anymore ?

The BEC may have been overloaded, and the jet being nose heavy could have caused that outcome if the servos don't have enough power to hold stab trim.

Plus, there is the structural issue I talked about.

[Gringotuerto]

wish to find the blubox, i’ll be back Saturday at the field to see if anyone find something

Sorry if you already explained this, but did you have the elevator passing through the blue box? My Mig came with an extra Y-cable (with the Y at the extreme end...in other words splitting immediately after the receiver end and having two separate cables running to the servo end). There were instructions or suggestion somewhere (I think an additional note in the box) that explained that this was an "optional" upgrade to bypass the blue box specifically for the elevator. I took this as a tacit admission that the stock setup through the blue box (which involves a length of single-path cable, an extra pin connector, and routing through PCB traces on the blue box) was "possibly marginal" in terms of IR drop for the elevator.

To me all the user-suggested upgrades are just ideas for consideration; But when the manufacturer suggests an upgrade, I assume there is a solid basis for it.

Anyway, I also have to compliment you on the job you did on this plane. It looked excellent! Good art, good workmanship.

[crxmanpat]

Take off: yes i did use flaps.
shortly after I’m always gear up and flaps up , as always i do .

The reason I asked about takeoff flaps is that your plane seemed to exhibit the exact same symptoms of other crashes where flaps were down and the jet was flown at higher than approach speeds. It seems the flaps blank out the elevators completely, and no matter how beefy the servos and control rods, there is no pitch authority at all in this condition and the plane nose dives.

Not saying you definitely did not put flaps up after takeoff, but your description of the crash seems eerily similar others where flaps were down at high speed.

Again, sorry for your loss.

[Airguardian]

I'd say that from the evidence so far, it's more likely a structural overload problem than an aerodynamic blanking one.
If the stabs were blanked out, they would not deform as Bajora's pic and Fred's video showed that they did.

[Elbee]

Thank you very much for the love guy’s... I saw after the crush one elevator still connected to the servo . The other can be find it...impact was hard.
in few months will be my b-day...might ask for another one? THANK YOU TO ALL OF YOU

GW, so sorry to read about your incident. Birthdays are magical days. She was a beauty, Possibly you can rebuild? Best, LB

[Griffon Wings]

Hi Griffon Wings....

Please confirm that you did not have add-on RF choke filters installed. It does not appear that you added RF filtering via ferrite chokes.

This is a well discussed topic in this forum. No guarantees, but they can’t hurt, and might actually prevent loss of control like this.

Thanks,
-GG

Hey GG, no i did not have it installed.

[Griffon Wings]

Brothers oh brothers ,
my very last wish is to give negativity to this plane ,
I’m thinking so hard in my little known on the rc world what can be got wrong.
because i’m not an expert, just a hobbies like you having fun .

there are many videos of pilots having a blust with this jet.
The work behind it we all know is extended to so many levels and i don’t want to diminished this for a crush . I think is very irresponsible from me to make you think this . Please don’t.

Can we say , maybe , in the first crop, maybe again , there was few of “ something “ wrong with it ?
maybe just a few, maybe !!
can happen , so pilots mistakes can happen too.
unfortunate, but happen .
miss tiny solder ? Who knows.


Let put it in this way, i test the candy and know i want to eat it. My plane is behind repair, unless your name is Merlino 🧙♂️.

Will i get another when in stock again ?
most probably, the only reason is because I believe in this company and their products. All the way.

i share my experience guy’s , but I don’t want to take down this project.

let think positive, soon the new batch will be back and so many other to choose and new one to comes.
in one way or another i’m surly will add another great jet in my hangar ( from Morion )

as philosophy teach : **** happen , sorry for my “ french” .

new year , less restrictions, more planes !

let focus more on Airguardian or Jeremy Salt and many others showing how great this jet can be .
I wrote wile ago ,of two pilots flying this plane at the field and their smiles after landing was ear to ear .



Always apologies for my English but a sincere thank you for the comments.
thank you for make me part of this Great Family !

all my best

[Airguardian]

As long as there is willingness to communicate, 'bad english' is not a problem ;)