First we already have a lot of real data. Even once we get his additional data we still need to each, individually, decide on what correction is needed.
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Official Freewing MiG-29 Fulcrum Twin 80mm Thread
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Hi everyone,
Here is my remedy for elevator issue.
The Promodeler DS150CLHV servos arrived today. They are a direct drop in. No modding required. Except they use 4 screws instead of two. 115 oz/in on 4.8V
In regards to the rods, I found a tube I had purchased for 3D printer years ago. Turned out the internal diameter and OD are exact match for the stock carbon tubes and rods. Will prevent the rod from deforming inside the carbon tube.
I removed the super long 60cm elevator extensions and installed super short 13" ones. Was enough considering the length of the servo wire and the aft position of the receiver in the hull.
I have an alarm setup in my radio when flaps are extended AND landing gear is retracted. Prevents flying with flaps extended.
I feel quite comfortable flying it in this configuration.2 Photos
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Originally posted by RedAlert View PostHi everyone,
Here is my remedy for elevator issue.
The Promodeler DS150CLHV servos arrived today. They are a direct drop in. No modding required. Except they use 4 screws instead of two. 115 oz/in on 4.8V
In regards to the rods, I found a tube I had purchased for 3D printer years ago. Turned out the internal diameter and OD are exact match for the stock carbon tubes and rods. Will prevent the rod from deforming inside the carbon tube.
I removed the super long 60cm elevator extensions and installed super short 13" ones. Was enough considering the length of the servo wire and the aft position of the receiver in the hull.
I have an alarm setup in my radio when flaps are extended AND landing gear is retracted. Prevents flying with flaps extended.
I feel quite comfortable flying it in this configuration.
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Originally posted by Bushong572 View PostChanged the wheels to JP 45mm front/ 65mm rear (with brakes)
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Originally posted by DForbes View Post
Great looking servo but that's crazy $. Not spending another $100 for servos that should have been on this plane to begin with. Freewing needs to get ahead of this.
The way I see it, any jet would benefit from a servo on a FFS that centers well, and doesn't develop a deadband zone. Resulting in a more locked in feel in the air.
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Originally posted by DForbes View Post
I have these on my SU30 and love them however the axle shaft on mine is a bit short and will not reach the other set screw. It hasn't been an issue but I inspect them every few flights to see if if it loosens. What is the length on these and can you show a close up of the axle shaft to wheel assembly?
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image_63992.jpgimage_63992.jpgOriginally posted by Bushong572 View Post
I reused the stock freewing axles (front and rear).
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I calculated the CG on the Mig and 140 mm is 25% of MAC. 30% is 165 mm which I think not unrealistic. There is no other reason that this thing should need 6 degrees up elevator just to fly level. It is not surprising the servos are overheating. Maybe using analog servos instead. At least we could have smoke trails
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Originally posted by Eric D View PostI calculated the CG on the Mig and 140 mm is 25% of MAC. 30% is 165 mm which I think not unrealistic. There is no other reason that this thing should need 6 degrees up elevator just to fly level. It is not surprising the servos are overheating. Maybe using analog servos instead. At least we could have smoke trails
We have good data from Firebird, but we must have the flight data. Then like Evan said, each of us can decide on what correction is needed.
-GG
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Originally posted by Eric D View PostI calculated the CG on the Mig and 140 mm is 25% of MAC. 30% is 165 mm which I think not unrealistic. There is no other reason that this thing should need 6 degrees up elevator just to fly level. It is not surprising the servos are overheating. Maybe using analog servos instead. At least we could have smoke trails
+16 didn't feel horrible, but still somewhat on the nose heavy side for sure.Freewing A-10 turbine conversion: http://fb.me/FreewingA10TurbineConversion
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I mentioned about a week ago about a problem with the MiG. During flight condition with flaps deployed and higher throttle settings, with nose down attitude, the MiG loses elevator control. Please see my previous posts. I was able to reproduce the pitch control instability multiple times. Last Sunday, I had someone take close up burst photos during this maneuver. Unfortunately during my last try, I was not able to pull out of the shallow dive with up elevator input on my transmitter. The MiG was destroyed on impact. I have a picture, moments before impact, that demonstrates a structural problem with this plane. See below. Please note the anhedral configuration of the horizontal stabs. I’m convinced that this is contributing to the loss of elevator control. My advice, please do not fly your MiG with flaps deployed at higher throttle settings
1 Photo
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Ok, so new questions here come to mind (Motion should send you at least two jets free of charge for your testing and rather tragic discovery)... can you examine the stab mounts after the impact?
What gave way? The foam, the plastic? Was your airframe badly glued? Of course the impact damage may make it hard to tell.
Others having crashed their MiGs, please do this exercise too if you conserve the pieces now that we know what to look for... try to force the stabs into anhedral with your hands and try to identify where is the structure failing.
Good news: Knowing the problem is most of the way to solving it.
Bad news: This probably does not have an easy fix.
Reflection: Wonder why no more jets are falling from the sky considering this structural problem.
Maybe it's just the jets that didn't get properly glued at factory? F-18 case repeating all over again?
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But....Considering that high speed/high throttle condition with flaps down is not a normal nor advisable realm of flight, it appears the MiG is being pushed beyond its design limits.
Sorry for the loss! Thanks for capturing what appears to be a notice for all MiG drivers of a flight condition that must be avoided. Be cognizant that a V(FE) is at play here (max flap extension speed).
-GG
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