Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[fredmdbud]

bye

[kallend]

I'm unsubscribing from this and the thread in RCG. Nothing but the same ol same ol...

OK.

[radfordc]

I'm unsubscribing from this and the thread in RCG. Nothing but the same ol same ol...

You can tell Evan is a pilot....announcing his departure!

[fredmdbud]

More tests with bigger batteries. Caught early, stabilators can recover, but if with enough speed gained (last test), the problem appears; flaps-up fixes things. This might be a reason they went up to 30g.

It may seem very brief, but you lose a lot of altitude quickly when at full throttle.

[Hugh Wiedman]

It seems that a picture (or video in this case) is worth a thousand words. Those stabs really flex at full throttle and flaps!

[GliderGuy]

More tests with bigger batteries. Caught early, stabilators can recover, but if with enough speed gained (last test), the problem appears; flaps-up fixes things. This might be a reason they went up to 30g.

It may seem very brief, but you lose a lot of altitude quickly when at full throttle.

Excellent video study! What servos was this done with?

The video shows why my first flights with the original 17g servos didn’t have issues…..I flew it like a grandpa: 1/2 throttle and no flaps until slowed on down wind after the gear was down. Faster flying was only done after upgrading the FFS servos.

-GG

[kallend]

So very strong evidence of an aeroelasticity problem that may be overcome by brute force.

A more elegant solution would be a redesign of the stab pivot geometry and mountings to reduce the flexing forces and increase the structural stiffness.

In my opinion (which is unchanged since last year).

[fredmdbud]

And uneconomical. Very academe.

[Hugh Wiedman]

I'm unsubscribing from this and the thread in RCG. Nothing but the same ol same ol...

When you gotta go, you gotta go. Makes sense to me!

[fredmdbud]

Last flaps-test video for now, including tufts to show airflow over the stabilator, with close-up clip of the dive at the end.

Captain MoMo in the background ("When are you going to dive?")

[kallend]

And uneconomical. Very academe.

Brute force is a Band-Aid fix.

[fredmdbud]

Brute force is a Band-Aid fix.

A Band-Aid fix today is better than a redesign years away.

Or just widen the flap span - they're not molded on the wings, and are an easy DIY project (balsa).

But probably not good enough for you, so just don't buy it (which I suspect is the case).

[4qr1hu9n7]

Why would anyone be foolish enough to deploy flaps at full throttle ?? Clearly exceeding the flight envelope of the model.

[radfordc]

Why would anyone be foolish enough to deploy flaps at full throttle ?? Clearly exceeding the flight envelope of the model.

Thank you so much for your wise counsel...of course no one ever had this thought before so you have been quite helpful.

[Airguardian]

A Band-Aid fix today is better than a redesign years away.

I already provided a much more elegant band-aid fix 'yesterday'.

Glass the stabs with a continuous ligthtweight cloth (WBPU will do), closing the profile.
Reinforce stab assemblies (easier way to do is by epoxying in the verticals).
Add some stronger servos too. Use a proper linkage. Shift CG aft, 15mm minimum, reflex airfoils. Boom, done.

[fredmdbud]

Then prove/demonstrate it?

[locharrow]

This is what my honest trader in China tells me regarding upgrades...

"Hi thank you for your reply. Yes, the elevator servos are 30g now. Thank you.
However, the Mig29 in our stock has 23g elevator servos. And after the stock is sold out, we will have Mig29 with 30g elevator servos. At the same time, we will try to buy 30g servos from Freewing if they have it now. If we get 30g servos, we can replace the servos for you as well. Thank you.

My plan is to fit a pair of CF rods in the underside of each stab and as a belt and braces fix get on my knees and pray for a week before maiden. Having plenty butt puckering flights with the Freewing F4 to worry about what happens when the Mig arrives!

[fredmdbud]

This is what my honest trader in China tells me regarding upgrades...

"Hi thank you for your reply. Yes, the elevator servos are 30g now. Thank you.
However, the Mig29 in our stock has 23g elevator servos. And after the stock is sold out, we will have Mig29 with 30g elevator servos. At the same time, we will try to buy 30g servos from Freewing if they have it now. If we get 30g servos, we can replace the servos for you as well. Thank you.

My plan is to fit a pair of CF rods in the underside of each stab and as a belt and braces fix get on my knees and pray for a week before maiden. Having plenty butt puckering flights with the Freewing F4 to worry about what happens when the Mig arrives!

Motion RC has been pre-emptively providing 30g servos and upgraded rods with MiG-29's purchased since May.

Will be interesting to see the specs of the servos the Freewing factory will start installing.

[GliderGuy]

Then prove/demonstrate it?

(Edits added after original post)

Thanks Fredmdbud for the videos..

Band aid fixes work good enough via demonstrated success. For sure I DO NOT fly fast with flaps down and have no desire to push the flight envelope into that realm of no man’s land.

Happily pushing well past 1,000 flights and still going strong courtesy of multiple band aid fixes. The main one I did not do was glass the FFSs. But, that’s my choice. So far, one aileron and one rudder servo needed to be replaced (they started to chatter) just to be on the safe side.

By my count, I did 15 band aid mods suggested by the group think or discovered on my own (like beef up the main gear attachments and adding RF chokes). Many of the mods were likely not needed, but were implemented during the early phase of this forum when the real cause of the crashes was unknown. None were hard to do.

I love this EDF!

-GG

Aside: Some of you in the past have asked how well the batteries have held up. The Admiral Pro 6000 50C batteries put into service 04/2020 have finally started to show signs of their 14-month age. All have a very slight puffing and the internal resistance readings are starting to creep up. Time to spend some $$$. They've supported a large number of flights with the AL37, F-4 and MiG. I got my money's worth outa these (charged at 4.5 amps, consumed about 4000 mAh with a typical flight profile, never charged below a 50F outside air temp, no cool down after a flight...put them right back on charge upon landing).

[xviper]

Band aid fixes work good enough via demonstrated success. For sure I DO NOT fly fast with flaps down and have no desire to push the flight envelope into that realm of no man’s land.

Happily pushing past 1,000 flights and going strong courtesy of multiple band aid fixes. The main one I did not do was glass the FFSs. But, that’s my choice.

By my count, I did 15 band aid mods suggested by the group think or discovered on my own (like beef up the main gear attachments and adding RF chokes). Many are likely not needed but were implemented during the early phase of this forum when the real cause of the crashes was unknown. None were hard to do.

I love this EDF!

-GG

That in itself, may be the critical factor in your success with this plane.
That's astonishing! Between this plane and your AL-37, how do you find the time to fly so much and are your thumbs worn down?

Something must be working for you but perhaps the only one that really made the difference was NOT flying fast with flaps down.