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Old Apr 07, 2012, 05:29 PM
Add Lightness
MNadMan's Avatar
United States, MN, Minneapolis
Joined Dec 2011
302 Posts
My 35mm MiG-29 flies real nice and level out of my hand everytime! if... I launch it on 1/2 to 2/3rd power. if I try to launch on full throttle, it's trouble.

The one thing I'm amazed by this plane is how it handles the wind for it's tiny size. the wind does not seem to blow it around, it just cuts through.

Full throttle seems to not ad much other than more noise and makes it fly a little worse.

I bent up my nozzles to fix the stock down thrust issue. it you just cut the glue joint on the bottom of the area where the nozzles connect, then you can bent them up. then I used some packaging tape to make a 1/2 thrust tube to fill the gap. works great.



Quote:
Originally Posted by Joe 1320 View Post
I took a few more flights on the Mig-29 before sunset, the performance on 2s stock power and no programmed transmitter rates is adequate. I have extra elevator reflex manually set and ailerons set to neutral. Roll rate could be quicker, I'll dial that in next. Takes a little down stick to hold inverted, rolls will drop a little altitude on the back half, loops are a little sloppy. Make it a little more like a corkscrew and it goes though fine.

To me it seems to be a tough model to get the launch just right. It's easy to grab, easy to throw, I think it's the thrust line issue that's bugging me. My F-18 launches out straight as an arrow every time, no pitch changes with throttle and that's what I expect. Unmodified it is still manageable, I'm just not satisfied yet.
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Old Apr 07, 2012, 07:47 PM
Luck is my skill
queadlunnrau's Avatar
United States, WA, Redmond
Joined Jun 2009
1,075 Posts
Tutorial plz!
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Old Apr 07, 2012, 08:21 PM
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Joined Dec 2011
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Tutorial plz!
I second this with extra please on top!
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Old Apr 08, 2012, 04:25 AM
Mike
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Joined Dec 2010
750 Posts
I had a look at my F-86 again to examine why it was not flying as expected.

I did the following mods and it tracks much better.
- made aileron pushrods from a stiffer material
- bent slight polyhedral in the wingtips
- added wing fences made from clear lexan. Now, I do not know if this has any effect but I thought that since I am at it, I might as well give it a go anyway.

Skyangel/Jpower F-86 Sabre (2S) post mod flight (5 min 46 sec)


It now tracks well enough for me to be comfortable to buzz my head.


I noticed that there is quite a fair bit of upthrust. Looking at the plane, I don't know how to fix it. Any suggestions? Meanwhile, I will do a throttle-elevator mix for this.

The exhaust of the F-86 is also smaller than the Mig15, which gives it less static thrust but more top end speed. This explains why I find it the hardest to launch. I will leave it as it is.
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Last edited by miketre; Apr 08, 2012 at 04:35 AM. Reason: attachments
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Old Apr 08, 2012, 12:34 PM
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Joe 1320's Avatar
United States, FL, Sebring
Joined Feb 2006
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I increased the rates on the ailerons, took the Mig -29 out for a couple more flights. Flys fine now. I also pushed the lipo a little more forward and hand launch was uneventful. 2/3 throttle and it went out straight and true. I even pulled a loop from level flight downwind. So on 2s the plane can perform fine with no nasty traits left except the pitching up when power is cut. If you use landing gear, you'll have to keep power on and fly it down to the deck before cutting power. If not, it will pitch up and stall. I'll fix that next.
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Old Apr 08, 2012, 04:10 PM
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Angelo's Avatar
Chicago, IL
Joined Nov 1999
2,048 Posts
Quote:
Originally Posted by miketre View Post
I noticed that there is quite a fair bit of upthrust.
That is not upthrust, the exhaust is merely cut on an angle, like the full scale F-86. If you look in the tail, the duct goes straight to the fan, there is no bend.

The thrust lines are fine on the F-86, throttle changes don't have a lot of effect on pitch once you get it dialed in. Of course, on 2s it's usually flat out all the time anyway.

I also replaced the aileron push rods with thicker wire, but that was as much about getting a better, tighter fit in the servo arm holes. Those bends you put in will make it "springier", straight wire will not flex as much.
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Old Apr 09, 2012, 02:12 AM
Mike
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Joined Dec 2010
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Quote:
Originally Posted by Angelo View Post
That is not upthrust, the exhaust is merely cut on an angle, like the full scale F-86. If you look in the tail, the duct goes straight to the fan, there is no bend.

The thrust lines are fine on the F-86, throttle changes don't have a lot of effect on pitch once you get it dialed in. Of course, on 2s it's usually flat out all the time anyway.

I also replaced the aileron push rods with thicker wire, but that was as much about getting a better, tighter fit in the servo arm holes. Those bends you put in will make it "springier", straight wire will not flex as much.
Angelo, thanks for the reply.
The bottom part of the exhaust tube tapers upwards. Doesn't this blow the air upwards? I'm not technically inclined in these and could use some education.

What I do notice is that the nose drops suddenly off throttle. I don't believe this is a CG issue, because when I move the CG back, it will go to the point where it flies at high alpha after launch and is stuck at that attitude.
I'm going to mix this out for now.

Noted about the bends in the pushrods. This wire is much stiffer and has lesser flex than the stock one even with the bends.
I did make them straight before this, but could never get the right length. you can see from the quality of the bends that building is not my forte. haha
I thought about bridging the bends with a CF rod after I adjusted the length, but the little flex hasn't bothered me yet.
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Old Apr 09, 2012, 08:05 AM
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Chicago, IL
Joined Nov 1999
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Miketre, the thrust tube narrows down a bit as it comes back from the fan. The bottom does angle up a bit, but the top angles down about the same. Don't have it in front of me, but that's how i remember it.

Mine also drops the nose if you chop the throttle, but I think that's because the nose scoop goes suddenly from inhaling lots of air to blocking it when the fan stops, creating a fair amount of drag. My Kyosho A-6 does the same thing. Once it settles in on glide, it still glides pretty well.
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Old Apr 09, 2012, 03:34 PM
Luck is my skill
queadlunnrau's Avatar
United States, WA, Redmond
Joined Jun 2009
1,075 Posts
My F-15 is here!!!

I was a little worried when I saw it shipped from China and not Canada, but 11 days from ordering to my door, is not bad! I think it woulda been 9 days had my work been open on Saturdays to accept.

Sor for anyone wondering about hobbyb.com they did me good! Thanks Hobby B!

Plane came in prestine condition no warping, can't wait to assemble it tonight!
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Old Apr 10, 2012, 01:37 AM
Luck is my skill
queadlunnrau's Avatar
United States, WA, Redmond
Joined Jun 2009
1,075 Posts
F-15 Finished

I went all out on this one, magnetic drop tanks, o-rings on the linkages, carbon rod re-enforcements, beefier linkages, silver sharpie.

Bench tested her on 3s using the 3 bladed fans on the stock esc's. So far so good! My temp guage batteries died so I used the old hold on for 5 seconds method. After more than 4 minutes of running an 850mah 3s, the ESC's were hot, but not too hot I could hold them, I'd guess maybe 130deg f, but will test again when I get batteries for my temp guage again.

The lipo compartment is HUGE I can almost balance a nano-tech 3s 850mAh.


Update, ESC's fried on 3s with the 3 bladed fans on pre-flight checks for maiden.
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Old Apr 10, 2012, 01:41 AM
The stalling italian
gionir's Avatar
France, RA, Lyon
Joined Jan 2011
285 Posts
Man that is SUPER sweet. After seeing yours I am thinking to get one as well!
Did you use Krylon paint?
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Old Apr 10, 2012, 01:43 AM
Luck is my skill
queadlunnrau's Avatar
United States, WA, Redmond
Joined Jun 2009
1,075 Posts
Quote:
Originally Posted by gionir View Post
Man that is SUPER sweet. After seeing yours I am thinking to get one as well!
Did you use Krylon paint?
Just used a silver sharpie!

The silver and gold sharpies are basically paint pens.

Normally i use acrylic from my wifes painting supplies, but this way the sharpie wouldn't add too much weight.
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Old Apr 10, 2012, 01:50 AM
The stalling italian
gionir's Avatar
France, RA, Lyon
Joined Jan 2011
285 Posts
Quote:
Originally Posted by queadlunnrau View Post
Just used a silver sharpie!
Oh, I tried once to use a sharpie on my UM P51 and made a hole through the fuse

maybe it's a different foam then...

This opens up infinite possibilities! Thanks for the tip!
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Old Apr 10, 2012, 02:55 AM
Mike
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Joined Dec 2010
750 Posts
That's a much better looking F-15 than the stock paint scheme. I wish I had half your modelling skills!
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Old Apr 10, 2012, 02:53 PM
Luck is my skill
queadlunnrau's Avatar
United States, WA, Redmond
Joined Jun 2009
1,075 Posts
Update, ESC's fried on 3s with the 3 bladed fans on pre-flight checks for maiden.

Time to order some plush's
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