Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[Gringotuerto]

Going back several pages where there was someone who had one of the nose gear doors catch on the strut and jambed up the retraction, I mentioned something about adjusting the "rod". Now, I'm not sure about whether or not this came into play but the owner indicated there are NO rods for the doors. Well, in fact, there ARE rods and the length of each rod determines how far each door goes open and whether or not the doors close flush. He went on to say that altering the strength and length of the spring fixed his situation.

1. For those of you who don't have the plane yet, below is a photo of the front gear door design. When the gear is up, the rod length sets the position of the door. The spring sets the opening force. Several people reported removing the spring and shortening it a bit.

2. I didn't see mention of this anywhere in the manual, but I noticed that the model comes with a Y-cable for the elevator. I had set it aside and forgotten about it. You have the option of using this Y-cable instead of going through the box, which might have the advantage of lower resistance. I didn't measure resistance, but the wires are parallel directly from the Rx (and therefore half the resistance) for that length. Also it results in one fewer pin connection in the path than the stock "cable-box-cable" arrangement. So overall I'm guessing the current capacity is a tiny bit higher. I'm going to change it out, just because I want to maximize elevator performance. It should be self-explanatory, but also somebody posted a video of how to change it out (in Chinese, but visually clear):

Link to video on Y-cable:

https://www.youtube.com/watch?v=uzURtWArsCQ

Pic of front gear door mechanism:

[GliderGuy]

I did the original post on this. Sorry....I meant to state “no servo-activated door rods”. My bad.

What I finally settled on was to move the “stock” springs to the anchor posts nearest the centerline of the fuselage...there are 2 spring posts on the white plastic activation rods.

RESULTS
————

- Doors still close easily enough w/o placing too much load on the gear retract servo.
- Not 100% a solution. If I don’t slow down before hitting the retract switch, the door(s) “may” blow in enough to catch the shaft and/or wheels and hangs.
- If I hit the retract switch right after take-off and under full power, original spring anchor post position would allow the gear to hang 80% of the time. After moving the springs’ anchor points, it’ll hang maybe 10% of the time. Great improvement.

Total solution that works 100% of the time = Take off, climb to downwind, leave flaps down, slow to less than 1/2 throttle, level out, retract gear. Note: With the spring on the original post, this worked only 90% of the time.

I’m OK with the results. I can still make jet-like climb-outs after take-off with gear and flaps down.

-GG

[janmb]

Now that my Mig has arrived and is on the table, I can see what everyone is talking about.
The throttle lines on this plane are "Y'd" near the end that plugs into the RX. It's not that hard to do the throttle calibration by unplugging one line and doing the calibration one at a time. On the other hand, on twins where there are separate batteries for each ESC, I generally can hold both battery leads in one hand and plug both batteries in fast enough that there is very little lag time. If you can't plug them in fast enough, then one ESC will go into programming mode before the other one has finished the initial beeps. If you pull the stick down at that time, you've calibrated one ESC and set the BRAKE on the other, then we see posts like "Woe is me" from those who can't figure out why one ESC has the brake set.
As far as the throttle trim is concerned, most manuals say nothing in this regard, while some say to lower it to the bottom while yet others say to leave it in the middle where it starts out. Eflite does this on some models, as do many VTOL planes. So, unless it says otherwise, on any new model, I start by lowering the trim to the bottom. Rebind when the plane is finally set up, then go flying. How you do it is up to you.

Regarding calibration: My point precisely. Get the timing wrong, and the stick pulling can easily do stuff you don't want. Far easier to avoid by doing one at a time imo.

Regarding trim, I remove it all together, and use my servo setup to determine whatever travel I want for my throttle channel. Some ESCs may have requirements in that regard, but if so, I still prefer to sort that out in my throttle channel travel configuration rather than mess with trim - which sooner or later you end up using/touching inadvertently.

[janmb]

The easiest way is to make a Y-lead from one battery (preferably small, like 3S/2000mah) with two connectors on it... Plug in the battery and calibrate both ESC:s at the same time. And by using a smaller battery you don't need to have the scary 6S/4Ah+ batteries on the workbench.

I use a small battery on my 6S models for testing on the bench. With a long lead >30cm/12" it can lay on the bench no matter if the aircraft is upside down or not, thereby no need to tuck the battery in when testing landing gear and such.

That is indeed a great idea

[Lcacing]

We now got two MiG’ at our field!!!

[janmb]

If you've ever noticed, the low end of the throttle sometimes has a "dead zone" where the motor doesn't start spinning until the throttle is advance to 5-9%.

I have experienced that on certain models, but if that happens, either the ESC calibration failed, or the ESC is garbage in the first place. I would still claim trimming is a poor fix for that.

Also, if the ESC is worth a damn, if you trim up as much as 5-9% over the value the ESC was calibrated with, it ought to refuse initialization upon powering on the model (nm, I see you already addressed this)

I of course agree completely that you should never accept a dead zone of that size on your throttle stick.

My reason for having a gripe with using trim for electric setups is, as you also mention, the need to remember to always dial it back down, and the way this invariably will lead to mistakes.

If nothing else, I would recommend using the throttle cut function to solve this problem (a mandatory setup in any case!). Still has the drawback of requiring pilot discipline, but at least just a two position switch rather than a precise amount of trim clicks.

[janmb]

300 flights on twin 80mm 6S birds, that’s great! Good size data set.

How many of those are on full flying stab twin 80s?
ie not the A-10 etc?

Lets say the F-14 and Mig-29? Maybe others?
I have somewhere north of 500 between 2 F-14s and now 50+ on the new Mig.

It is pretty brilliant that you still fail to realize how little that experience matters when you quite clearly are oblivious to basic physics and engineering in general.

Your flying a model, regardless of type, has simply no relevance when it comes to your basis for an opinion on the topic we are discussing. Which your stand point also clearly demonstrates.

Theres an INSANE amount of speculation on the forums about FREEWINGs decision to ship with the 17g, but the data set that they have gathered show FAR FEWER crashes on the 17g set up, than other legacy full stab models. (F-16, F-22, F-15, etc)

The only insane thing about this is your level of insisting on having conclusions that we, including MRC, totally lack a sufficient sample size for yet.

You also seem bent on thinking this boils down to practical testing exclusively, and refuse to listen to any sort of basic engineering principles. (which ironically also obviously is the basis for Alpha's decision to go for a free upgrade - at a time where no statistically significant data were available what so ever)

[xviper]

@Jacckall and @Radar-Guy Thanks for the pictures of the "real" thing.

[Gringotuerto]

I did the original post on this. Sorry....I meant to state “no servo-activated door rods”. My bad.

What I finally settled on was to move the “stock” springs to the anchor posts nearest the centerline of the fuselage...there are 2 spring posts on the white plastic activation rods.

Thanks for the tip, I didn't notice those until you mentioned them. Seems easier than physically shortening the spring, and should have similar effect.

[Swarick]

It is pretty brilliant that you still fail to realize how little that experience matters when you quite clearly are oblivious to basic physics and engineering in general.

Your flying a model, regardless of type, has simply no relevance when it comes to your basis for an opinion on the topic we are discussing. Which your stand point also clearly demonstrates.




The only insane thing about this is your level of insisting on having conclusions that we, including MRC, totally lack a sufficient sample size for yet.

You also seem bent on thinking this boils down to practical testing exclusively, and refuse to listen to any sort of basic engineering principles. (which ironically also obviously is the basis for Alpha's decision to go for a free upgrade - at a time where no statistically significant data were available what so ever)

If you guys are done with your D**k measuring contest can we get back to discussing this airplane?

[pullupnow]

Flight number 3 love it!!

[janmb]

If you guys are done with your D**k measuring contest can we get back to discussing this airplane?

I would love to. You will have to tell Justin about that, he is the one doing the constant epeening, while I'm trying to apply actual engineering skills to avoid his biases from costing other customers their expensive jets totally needlessly.

[janmb]

Flight number 3 love it!!

Great job!

[Nike_Belli]

Not Bad Really!

[Evan D]

Yes!

If you guys are done with your D**k measuring contest can we get back to discussing this airplane?

[Evan D]

Do you really not see how annoying it is to some of us?

I would love to. You will have to tell Justin about that, he is the one doing the constant epeening, while I'm trying to apply actual engineering skills to avoid his biases from costing other customers their expensive jets totally needlessly.

[Gringotuerto]

Flight number 3 love it!!

Excellent flying!

By the way, what aileron rates are people using for maiden? My first flight is probably tomorrow, and I have my 100% point set up at about 43mm throw, per the manual. I was thinking of starting at 65% or 70% D/R on the ailerons. I have found Freewing manual recommendations in general to be very conservative on CG (i.e. forward), but too adventurous on aileron throws. Also, I've never flown a delta wing before, and a delta seems harder to control on the roll axis.

[RCjetdude]

I am getting ready to maiden mine. How much if any flap-elevator mix is anyone using? I gather it needs up elevator with flaps?

[Lcacing]

I am getting ready to maiden mine. How much if any flap-elevator mix is anyone using? I gather it needs up elevator with flaps?

At the CG I’m flying, back about 15mm, no flap-elevator mix is needed. I think probably even at book CG no mix is needed.

[GliderGuy]

To each his own, but I successfully maidened with the following:
- CG on the mark
- No flap/elevator mix needed
- Control movements set to the book
- - adjust your rates to achieve these
- Maidened on LOW rate
- 3 mm vs 1 mm of elevator set (measured after the maiden trimming flight)
- No EXPO (but I am used to flying the F-4)
- - Suit yourself on this....maybe 20 to 30%

Don’t be concerned about this wing planform/flies like a dream. VERY honest bird.

On downwind, I reduce throttle 5 clicks starting from 1/2 throttle. On base...4 more. This leaves about 15% power. Over the fence and reduce to zero power....let her float down. Easy to land.

Read prior posts on getting into a FALLING LEAF stalled situation. Until we get this figured out....DON’T.

-GG