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Old Feb 14, 2013, 07:54 PM
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United States, TN, Jackson
Joined Mar 2007
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Originally Posted by kalmon View Post
Thats good to know... If the intake was above the waterline and the motor was also above the water you might have been able to water taxi it back!

-Brian
I actually thought about that but the aileron servos were fully submerged at that point...I didn't want to chance a major shorting out of the RX due to laziness......

Kevin
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Old Feb 15, 2013, 03:07 PM
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Joined Oct 2012
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I recently picked up a Mig15 and had my first flight today.

It didn't go well...

I replaced the stock battery connector with a female JST and performed air surface and servo tests on the bench. I used a fully charged 250 mAh 25C Thunder Power 7.4V LiPo that gives me no problems with my Carbon Cub.

First flight, the MiG went airborne after getting full throttle. She went up about 20 feet in air, very lethargic, and basically just stalled out and came down into grass. I was giving full elevator and this kept her nose up, but she just stalled and did a fast-glide into the ground. Total flying time: 5 seconds.

Changed battery. Bench tested again - motor putting a lot of air at WOT. Second flight - exactly same result.

Any ideas? The battery I'm using weighs a very tiny amount more than the stock (17g v. 14g). I see others in this forum using 325 mAh+ batteries that weigh a fair amount more without problems. Did I get a lemon? I appreciate your thoughts.
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Old Feb 15, 2013, 03:29 PM
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United States, MI, Grand Traverse
Joined Oct 2008
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Quote:
Originally Posted by pogeybait View Post
I recently picked up a Mig15 and had my first flight today.

It didn't go well...

I replaced the stock battery connector with a female JST and performed air surface and servo tests on the bench. I used a fully charged 250 mAh 25C Thunder Power 7.4V LiPo that gives me no problems with my Carbon Cub.

First flight, the MiG went airborne after getting full throttle. She went up about 20 feet in air, very lethargic, and basically just stalled out and came down into grass. I was giving full elevator and this kept her nose up, but she just stalled and did a fast-glide into the ground. Total flying time: 5 seconds.

Changed battery. Bench tested again - motor putting a lot of air at WOT. Second flight - exactly same result.

Any ideas? The battery I'm using weighs a very tiny amount more than the stock (17g v. 14g). I see others in this forum using 325 mAh+ batteries that weigh a fair amount more without problems. Did I get a lemon? I appreciate your thoughts.
Couple of things to check:
1) if at all possible try a different pack. Spec wise that batter has enough power to fly just fine. but, how old is it? There is no way to be sure it is giving enough power. The Cub requires about 1/3 the power to fly well compared to the mig.

2) check the thrust area. It is pretty common for the aileron wires to pull away from the sides and take the tape with them. The wires and tape have been known to block 30% of the air from the fan! This is a fairly common issue.

3) Try without gear and hand launch. The gear adds quite a bit of drag and can make a weak pack/block thrust problem more pronounced. This obiously isn't fixing the problem but it'll let you fly it a couple times to get a feel for the plane while you're troubleshooting.

If these don't help post back and there are more things to try.

-Brian
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Old Feb 15, 2013, 03:59 PM
Diverted by planks
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South Florida
Joined Dec 2010
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Quote:
Originally Posted by pogeybait View Post
first flight... didn't go well...airborne...full throttle....up about 20 feet in air, very lethargic, and basically just stalled out and came down into grass. I was giving full elevator and this kept her nose up...
Yup.


Two good minutes of video that might help:
Pilot error found in Air France Flight 447 crash (2 min 23 sec)
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Old Feb 15, 2013, 04:40 PM
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United States, MI, Grand Traverse
Joined Oct 2008
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Quote:
Originally Posted by tracknoob View Post
Yup.


Two good minutes of video that might help:
https://www.youtube.com/watch?v=QfF9ee4M_UQ


I originally though this as well, however the the mig should be capable of a 30 degree angle climb on a fresh pack. And it sounds like it was barely able to even get off the ground.

How long was the ground roll? how steep of a climb did you try? did you have the stick full back the entire flight or only at the very end?

-Brian
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Old Feb 17, 2013, 09:46 PM
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Joined Oct 2012
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Thanks for the comments and advice guys.

I tried a different battery and removed the landing gear, per kalmon's advice. Unfortunately, same result. I threw at full throttle, the plane glided downward which I corrected with elevator. The nose lifted up, but the trajectory of the plane (i.e., into the ground, at a glide) didn't change.

I understand that you can stall a plane by using too much elevator = reduced airspeed = stall. Here, I had to apply full elevator to get the thing off the ground. I might have eased back on the stick a little once it was airborne, but the plane was so lethargic that it was clear that trying to fly was futile.

I have quite a bit of time with my T-28, Radian, EZ*, Wildcat, Carbon Cub, micro T-28, P-51... this is a new problem for me.

Thanks for the advice guys. I think I need to swap or return this before it gets any more beat up.
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Old Feb 18, 2013, 06:36 AM
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United States, MI, Grand Traverse
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Quote:
Originally Posted by pogeybait View Post
Thanks for the comments and advice guys.

I tried a different battery and removed the landing gear, per kalmon's advice. Unfortunately, same result. I threw at full throttle, the plane glided downward which I corrected with elevator. The nose lifted up, but the trajectory of the plane (i.e., into the ground, at a glide) didn't change.

I understand that you can stall a plane by using too much elevator = reduced airspeed = stall. Here, I had to apply full elevator to get the thing off the ground. I might have eased back on the stick a little once it was airborne, but the plane was so lethargic that it was clear that trying to fly was futile.

I have quite a bit of time with my T-28, Radian, EZ*, Wildcat, Carbon Cub, micro T-28, P-51... this is a new problem for me.

Thanks for the advice guys. I think I need to swap or return this before it gets any more beat up.
Did you check the thrust area? I'd bet the aileron wires pulled out of the channel and are blocking part of the fan.

The other confusing thing is, with the gear off and a good toss mine will glide power off for about 15meters. This is motor off!! If on a hand launch at Full throttle you couldn't even maintain level flight something else might be wrong...
You might want to exchange it, just don't give up on the model as it is a great flying little plane!

-Brian
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Old Feb 18, 2013, 11:21 AM
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sussex England
Joined Jun 2002
461 Posts
Wonder if anyone can help.
I flew mine today for the first time in three weeks. It has had around ten flights before, all perfectly smooth.
Today it required a lot of right trim, AND you could see the gyros working very hard to keep it stable.
It was as if the gain had suddenly increased.
Weather was as per previous flights, nil wind.

Can't figure out what has changed.
(actually the only change is I enlarged the battery bay to move the 2s300 pack further aft, but the same problems occurred when I used the stock pack in the same location as before)
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Old Feb 18, 2013, 12:04 PM
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United States, CA, San Diego
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Birdseed, I understand if you don't keep the plane perfectly still at power-up, the gyros can be 'confused'. did you hold it still until it was all powered up?
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Old Feb 18, 2013, 01:56 PM
we can take off without that
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London, UK
Joined Nov 2008
784 Posts
I need a lot more practice at inverted flight. this happened after I righted the plane, then lost track of left and right, plus panicked reactions instead of calm and collected. its repairable but I think I will get a new fuselage.



Out of curiosity, since the nose is smashed, here is the weight of the front steering gear.

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Old Feb 18, 2013, 05:46 PM
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sussex England
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Green flyer-ouch!

Xmech2k,
I was less rigorous than in the past when it came to holding it still.
Does it matter how you orientate it when you attach the battery?
Could you attach the battery with the model inverted??
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Old Feb 18, 2013, 06:01 PM
ΜΟΛΩΝ ΛΑΒΕ
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USA, KY, Hebron
Joined Dec 2005
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Quote:
Originally Posted by birdseed View Post
Green flyer-ouch!

Xmech2k,
I was less rigorous than in the past when it came to holding it still.
Does it matter how you orientate it when you attach the battery?
Could you attach the battery with the model inverted??
Orientation makes no difference, so long as it is motionless. I always have mine upside down when plugging in.
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Old Feb 18, 2013, 06:05 PM
Dr John
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Lake Placid, Florida
Joined Dec 2001
2,712 Posts
Thr gyos will not initalize until you blip the throttle. You can plug the battery in in any position you want but then set on a level surface or just hold level and give her a quick blip of throttle to start the gyros. Always verify the gyros are working before a hand launch.

Dr John
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Old Feb 18, 2013, 06:21 PM
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Joined May 2007
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Pogeybait, EDFs have good straight line speed, but terrible climb, so you can't point the nose of an edf up until you have a good amount of speed to bleed off. All the other planes you have can do a very aggressive climb, with a lot of air over the tail.
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Old Feb 18, 2013, 07:48 PM
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United States, CA, San Diego
Joined Jun 2007
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Quote:
Originally Posted by pmpjohn View Post
Thr gyos will not initalize until you blip the throttle. You can plug the battery in in any position you want but then set on a level surface or just hold level and give her a quick blip of throttle to start the gyros. Always verify the gyros are working before a hand launch.

Dr John
I don't think so. See page 6 in the manual. The AS3X system initializes itself for 5 seconds when you plug in the battery, however it doesn't become active until you move the throttle. The gyros are working once initialized, but there is no output from the AS3X until the throttle blip or movement.
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