Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[radfordc]

With over 6 minutes of in-air time on such a large EDF, that's exceptional in my book. Contrast that with my E-Flight SU-30 (which I had to upgrade the fans to the FMS fans to get it flying decently) where with the same pack I'm barely over 3 minutes flight time. That's just enough time to settle in and the low battery voltage starts screaming and now I'm my pants cause I have to quickly get set up for landing!

Hugh, you really need to change the Su-30 over to dual 4000 packs! Six minutes of easy flying or 4:30 of roaring acro! Do It!!!

[Hugh Wiedman]

Hugh, you really need to change the Su-30 over to dual 4000 packs! Six minutes of easy flying or 4:30 of roaring acro! Do It!!!

I KNOW, I KNOW. Your mod to the dual ESC's and battery packs is definitely the way to go on the SU-30, and with those FMS 1920 Kv inrunners putting out an extra 25-30% over the stock E-Flight fans, it definitely is a much better flying bird. Just have that on the back burner because the Mig is already set-up nicely and get's the space in the truck when I go out. It's a shame we have to upgrade the power system so dramatically on a $600 E-Flight EDF to even get it to fly decently. Already have over $100 extra in it for the FMS fans, another $130 replacing the older 7channel Spektrum RX to the new 8 channel AS3X with a satellite RX and will probably make the modification one day, but hate loosing the air brake as it's kind of a cool item. Already too far down the "rabbit hole" with about $900 in this thing not to go the extra mile like you recommend! But knowing what I know now, the better option is the Mig, even with upgrading a few items!

[radfordc]

will probably make the modification one day, but hate loosing the air brake as it's kind of a cool item.

But knowing what I know now, the better option is the Mig, even with upgrading a few items!

A guy on RC Groups showed that you can put a 4000 battery under the air brake without disabling the brake.

After the upgrades to the Su-30 it flys just as good or maybe a little better than the Mig. It certainly doesn't have any of the Mig's bad habits.

[Airguardian]

[GliderGuy]

J - Nice evening flying….pretty flying. The MiG looks beautiful in the video.

I just made my last MiG landing 15 min after sunset. Cloudy but no wind. Good Texas winter day (52F).

-GG

[GliderGuy]

I noticed a main not fully retracting, Saturday. I could get it to go up, but only by flying at slow speeds. I've seen this before and know it is an indicator for needing a new retract servo. Started work on it Sunday morning and while inspecting things...found a crack in the other side's main gear plastic mounting box. I had spare mounting boxes, and I knew this type of crack (running front to back right by the servo motor's screw mount holes) wasn't going to be permanently fixable. Not at the weight of this bird.

BE CAREFUL...wires and spars abound on top of this area <toward the top of the wing that is>. Don't Dremel blindly. You may want to remove the wing to better see where things are.

So, 7 hours later I'm finally buttoning her back up. OMG....That main gear mount box is not a piece of plastic that is meant to be easily replaced!!!! I'm not gonna bore you with the details, but there are things going on in there that will offer up some surprises. Have your Dremel tool handy. I could only get the cracked mount out by Dremeling into small areas to pull out piecemeal. SURPRISE...there was a reason I couldn't pull it out. Read on....

What I found was...there are 3 screws (two at the front and one a the back) screwed in from the topside holding the box in. AND...there's no access to the screw heads. The heads are toward the top of the plane!!!! Maybe you could get lucky and punch a screw driver down from the top of the blended body area and get to the screw heads, but I just cut off what I could see with a Dremel tool...banking that my "build back" re-enforcement decisions would negate the need for the 3 screws. Time will tell. I sure as heck didn't want to punch 3 holes in the top of the blended body/wing area and go blindly fishing around for 3 screw heads way down in the bird. But, maybe that's the only way to get to the screw heads?

Again...after 7 hours of Dremel action, head scratching, carbon re-enforcing and epoxy mixing I AM FINALY DONE!. The box is as solid as a rock. But, will it hold up? I've been proven wrong before by repetitive applications of stress on a structure that I thought I had "fixed".

If you've got ideas how to get to the 3 screw heads without punching holes through the top of the blended body area, please speak up. I do not look forward to having to replace the other box when it cracks, if the only way to do it is the way I did it this time.

Anybody got a crashed MiG you could cut apart and shoot some pictures of what structure is above the main gear. I just tapped on the top of the blended body in this area of mine, and there wasn't a hollow sound. Is it even possible to push a screw driver down through what is above the main gear's mounting box?

Thanks.

-GG

[GliderGuy]

***Update to the below and above posts***

MRC Support was kind enough to send me some CAD drawings which (of course) agree with what I found when I attempted to remove the main gear plastic mount. Then, MRC stated the following (I paraphrase):

*****(1) Not designed to be replaceable
*****(2) Suggest you buy a new fuselage

OK...Which is what I sorta figured, but was hoping otherwise. AND...I appreciate MRC's help + CAD drawings. If you wish to see the CAD drawings, I have attached them as a PDF to which I added rectangles representing the 3 screws. Again, these CAD drawings were modified by me to show the 3 screws.

So..... (1) I may yet decide to poke a thin wire down through the foam and see if any structure would prevent getting a long thin screwdriver down to the screw heads from the topside. (2) If not, I will use the method I used for the first plastic mount when another one cracks.

=====ORIGINAL POST FOLLOWS========

Ref Post 5186

I contacted MRC support.

In parallel with that effort, does anyone have a crashed MiG-29 that they could study and determine if it would even be possible to poke a screwdriver down from the top of the blended body from above the main gear mount and get to the 3 screw heads? It will be a blind attempt to try to find the screw heads, but maybe that's better than having to hack the plastic main gear mount apart with a Dremel tool and remove it piecemeal...then having to grind off the 3 screws. Study the images, you'll see what I need information on.

Thanks for your help. #1 gear mount is done, but eventually another will crack and need to be replaced.

I'm pretty sure that my replacement work is plenty secure even with having to grind off the 3 screws. Time will tell.

-GG



CAD Drawings Modified by GG.pdf

[locharrow]

Well GG, it looks like you are going to have to go down through the top come what may so I would suggest drilling a tiny vertical hole up the way between these screws. Take exact distances and angles from the wee hole to the ground down screws you can see and use these as reference points to locate the screws from above. When you have these points marked, fish down with a needle on the points till you hit a screw head. Just my tuppence worth !!

[GliderGuy]

Well GG, it looks like you are going to have to go down through the top come what may so I would suggest drilling a tiny vertical hole up the way between these screws. Take exact distances and angles from the wee hole to the ground down screws you can see and use these as reference points to locate the screws from above. When you have these points marked, fish down with a needle on the points till you hit a screw head. Just my tuppence worth !!

Some good suggestions, there Locharrow. When I need to do another one, I'll consider your thoughts. Thanks.

-GG

[kallend]

*****(2) Suggest you buy a new fuselage

SUPRISE!

[GliderGuy]

SUPRISE!

LOL....No kidding.

The main take-away from all this is, "YOU CANNOT GRAB HOLD OF THE PLASTIC MAIN GEAR MOUNT AND PULL IT OUT OF THE FOAM!" Now we know.

Given the time it would take to "outfit" a new/virgin fuselage with all the stuff required (and the cost), the time invested grinding the cracked plastic mount out and cutting the 3 screws is a lot less effort and cost. AND...I don't see a set of digital camo decals for sale, either. So, you'd have to paint on the digital camo pattern. Hmmm.....

My grind-and-cut piecemeal removal method is beginning to look more "sane' all the time. It really wasn't difficult. It just took a lot of time. And, the amount of epoxy I applied to the replacement mount should ensure the 3 screws won't be missed.

I also took some time reinforcing, with carbon, the outside (the side toward the tip) thin foam shelf in the fuselage that the plastic mount's lip rests on. That shelf gets mushy from all the repetitive stress landings place on it.

Even though the two plastic main gear mounts were not designed to be replaceable...it can be done.

-GG

[Airguardian]

New air-to-air MiG video! (About time!)

J - Nice evening flying….pretty flying. The MiG looks beautiful in the video.

Thanks GG

[GliderGuy]

Update to post 5187…

I’ve made about 80 landings on the replaced plastic gear mount (I am on vacation…flying lots). I gave it a strong wiggle with my hand just now. It didn’t move at all….rock solid!

Most of the landings have been good, but not all. So, I feel confident that my replacement method WORKED!

Hope this nice weather holds.

-GG

[jetpltrich]

Got my MiG 29 a few weeks ago and have been slowly getting it ready for flight. I’ve perused the post on the MiG 29 posted here and have noted the suggestions and have watched the videos. I will reserve personal opinions and keep them to myself about suggestions and observations of flight videos.

From my calculations the CG reference points that the manufacturer has marked on the wing seems to be pretty close to accurate. What one can’t ascertain is the fuselage is a lifting body and thus this makes that calculation diluted. With that in mind and the batteries as far back as I can get them she was nose heavy. Attached for those that may be interested is my solution.

Three 450gr .50 black powder bullets installed where the drag chute would be put the aircraft within balance and I’m satisfied.

[kallend]

From my calculations the CG reference points that the manufacturer has marked on the wing seems to be pretty close to accurate..

Not sure what you mean by "accurate" in this context. After flight testing most people seem to have settled on 5 - 15mm behind the marks as working best.

[jetpltrich]

Not sure what you mean by "accurate" in this context. After flight testing most people seem to have settled on 5 - 15mm behind the marks as working best.

Whose flight testing are we talking about, the manufacturers or the individuals? All that I’m saying is when you sit down and do the math with respect to wing shape one can determine a pretty good location re: CG and based on that it’s pretty close. Then airfoil shape starts to play a factor. CG location is also dependent upon what you’re trying to achieve with the aircraft as well. When I do get this MiG in the air I may very well change things up. No need for a tone.

[kallend]

Whose flight testing are we talking about, the manufacturers or the individuals? All that I’m saying is when you sit down and do the math with respect to wing shape one can determine a pretty good location re: CG and based on that it’s pretty close. Then airfoil shape starts to play a factor. CG location is also dependent upon what you’re trying to achieve with the aircraft as well. When I do get this MiG in the air I may very well change things up. No need for a tone.

Suggest you read through this thread, and the one on RCGroups, rather than reinventing the wheel.

As far as the manufacturer's testing, their testers are the ones that released the lawn dart version.

[Evan D]

Deleted as immaterial to the discussion.

[jetpltrich]

Suggest you read through this thread, and the one on RCGroups, rather than reinventing the wheel.

As far as the manufacturer's testing, their testers are the ones that released the lawn dart version.

I believe I mentioned I read through this thread, I captured all the data, I never once said they were wrong, however, I did mention I have my opinions. I also mentioned I may, after my first flight, change the location as well.

My friend, your messing with the wrong guy here. I’ve been playing with RC aircraft since I was a youngster. I also fly the real thing, from singles to Lears to airliners and I’ve built two airplanes and these formulas to find CG locations don’t change from small to big. Wing shape does change ones perceived idea of where the location should be and so does airfoil shape. A Hershey bar wing will have a different location than a swept wing and when it comes to a swept wing that calculation is dependent on several key measurements. How you achieved your conclusion I’m “reinventing the wheel” eludes me.

You and I both have no idea what the manufacturers test criteria was when they tested this aircraft. We also have no idea the root cause of these “lawn darts” accidents, only pilot reports. No onboard data recorder to look at. With that conclusion we are at a loos and become the test pilots and though I am very well aware of the CG point location change it doesn’t mean one has to follow it. As I mentioned before I calculated it and it was pretty close to the manufacturers.

Happy New year my friend.

[kallend]

My friend, your messing with the wrong guy here. I’ve been playing with RC aircraft since I was a youngster. I also fly the real thing, from singles to Lears to airliners and I’ve built two airplanes and these formulas to find CG locations don’t change from small to big..

Ooooh - I'm impressed.

BTW, you aren't the only technically qualified person on this list.