I don’t have a Mig 29 but I have been reading about the unexplained crashes, I found this video on YouTube, I don’t know if it could help explain some of the crashes. What do you think? https://youtu.be/0c5aI7DpqkY
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Thanks. I put a stopwatch to the video. The servo tester completed a cycle in a bit less than 2 seconds. A tad less than 1 sec for each drive direction.
Timing the time spent in the stall, it appears it unstalls and reverses on the “reverse” drive signal. Seems to be functioning normally.
-GG
PS - If he were to grab the servo arm and hold it still for a bit less than 2 sec, it would unstall and move in the “correct” pre-grab direction.
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Originally posted by xviper View PostBut I'm not a "serious" competitive flyer and from my perspective, it didn't matter. Most RC flyers are not competitive flyers either. Same punch when taking off under my flying field conditions. Same flight characteristics. Same flight times. Knowing all this, seeing the IR readings don't mean anything to me and won't change how I do things on this topic. I just care about what I get out of my batteries at the field. There was no "noticeable temp effect" for us. I compare this to "pros" using a micrometer. We used a yard stick. I'm not telling anyone to do this or that, just relating my experience. If you want to buy battery heating bags, please do. I don't even think 50F is "cold", but that's just the way different people see things.
It's like professional race cars. Nitrogen in the tires means a lot to them and can win or lose a race. For the average everyday domestic driver? Really, nobody cares. (Except that the owners can brag, "I've got nitrogen in my tires!") But hey, if it matters that much to some people, by all means, go to the garage to get that tire top up whenever the pressure drops - and they do drop even if you have nitrogen in them. I'll just keep topping up with regular 80% nitrogen type air in my garage.
To the original poster who brought this subject up. Please come back and tell us what happened AFTER you cleaned all the stuck on grass build up in your fan area. Fly it with the same batteries at the same temp exactly the way you did the last time when it couldn't get off the ground.
PS. PieterO This is what he asked ...........................
My response was to him. It was based on my own experience. It was not designed to target anyone else. It was not meant to be a collision course with anyone else who might need to "correct" me or to "show me the light" or to show their immense intellectual prowess. It wasn't meant to be scientific and I said so (I was in medical science for 21 years, so I know about scientific process and what it can and cannot prove). It was purely to respond to him because he asked. If PieterO doesn't like that response, well, that's up to him and HE can take it up with me. If anyone else doesn't like my response, well, it wasn't meant for you. Fine, state your facts but I really don't need to "see for myself". If you're not PieterO, keep me out of it.
Yesterday, I made another two flights after cleaning the fans. I also heated the lipo's a little bit (to 20°) using the car seat heating. The difference with the troublesome flights in the weekend was huge. No problem at all at take off, much more power.
But since I changed 2 things at the same time... Personally, I think cleaning the fans solved the issue. There was really soooo much grass in it, collected at the stators...
Regarding the heating: I will give it another try when it's colder here. Shouldn't take too long. I will then perform two subsequent flights with cold and preheated lipo's so that I can experience the difference.
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Originally posted by themudduck View PostYeah in the video you can see that the end of the servo arm is cut off. So he was using the middle hole.
I don't think this is a mechanical issue, I think the elevators are not working due to some kind of radio issue. Its just flying along and all of a sudden - no elevator control. It doesn't make a lot of sense because we're all using different receivers. BTW I installed the chokes, but it happened to me on Saturday and as I reported, I managed to regain control just in time.
Here's a pic of me doing a knife-edge pass. It will hold this all the way down the line.
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I have the Mig-29 still in its box and that is where it is staying until I know what is the real cause of these crashes. As one post states has these small servos reached their limit. One thing to notice in the last crash he was working them elevator servos hard before the crash. I cant see that the aerodynamics of this jet can be at fault as it flies so well. Has anyone flying one of these Jets thought of using a separate battery and regulator to power the receiver and servos.
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Originally posted by GliderGuy View PostNeed to know more about the back story on the transmitter antenna...which we won’t. The potential of a weak RF link cannot be discounted. May not be the plane at all in this one instance.
More scrutiny of this crash is needed in regard to other possible causes. In this case...not possible to accomplish.
-GG
Flaps were also deployed at 4:01 in the video just prior to the crash. Not sure if he pulled flaps up prior to the high speed pass or not. I will test the effects of the flaps blanking out elevator control when I have someone that can film for me and the visibility improves. Need blue skies and some altitude. We're grey skies here right now.
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As an additional data point, toward the end of my flights, I always reduce to 1/2 throttle and shortly thereafter deploy the flaps to a max measured value of 30 mm (I have a stop glued onto my transmitter vernier knob for another plane’s needs).
The bird is still clipping along pretty fast at 1/2 throttle when I deploy the flaps. I haven’t seen an indication of elevator blanking over lots of flights.
-GG
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Originally posted by skybolt View PostI have the Mig-29 still in its box and that is where it is staying until I know what is the real cause of these crashes. As one post states has these small servos reached their limit. One thing to notice in the last crash he was working them elevator servos hard before the crash. I cant see that the aerodynamics of this jet can be at fault as it flies so well. Has anyone flying one of these Jets thought of using a separate battery and regulator to power the receiver and servos.
Despite of this, I decided to give it a go. Replacement servos fitted, new 2mm carbon tube reinforced control rods, 155mm CG and 3mm reflex at wing LE. Stock Blue Box wiring, but I’ve tidied up the wiring, saving 60g, all the RC components sit left and right of the aft battery with the afterburner control unit below the aft battery tray. I’ve replaced the stock BEC with a 20A YEP product (just for the peace of mind, the stock 8A BEC works flawless in my 80mm A-10 since 2017).
The maiden flight showed absolutely no bad tendencies, but I didn’t dare to go full power for longer periods. Yesterday, I flew her at maximum speeds for several runs. Again, no bad tendencies.
I don’t see a need for an extra battery, with strong elevator servos, suitable control rods in combination with the correct CG (IMO 155mm is spot on) and some reflex this is great model.
I’d like to say thanks to Brent Hecht for his efforts in sharing the “mod videos”!
I’m just wondering why we don’t see further comments from MRC regarding these crashes.
Frank
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Congrats on maiden!
Also good landing and... 6 min 10 seconds flight, not bad! :)
What were the battery cells voltage after the flight?
Originally posted by GliderGuy View PostI found another video by RC Plane Reviewer (the guy who later crashed in the video that started this discussion). [...]
I think we can safely toss this crash aside in regard to future posts. Comments?
He disregarded it totally and deleted our comments. You will find it's not a very receptive guy.
Other than that, I think his crash is significant nonetheless.
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Originally posted by HaroldAnderson View PostNoticed something else in the video. The flaps were still deployed here at 4:01 just before the final high speed pass attempt. The picture is from the video at 4:01. The flaps are still deployed during inspection of the wreckage. Would this not cause severe blanking of the horizontal stabs during a dive this steep and fast with flaps deployed? I will test this theory the next time I fly but I will be way up there.....
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Originally posted by Airguardian View Post
Some of us tried to warn him on his maiden flight video that his setup was showing clear signs of nose-heaviness and that he should be careful with that.
He disregarded it totally and deleted our comments. You will find it's not a very receptive guy.
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Originally posted by kallend View PostWhat kind of current draw would the flap servos need, in order to hold in the deployed position during a diving high speed pass?
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Originally posted by GliderGuy View PostI found another video by RC Plane Reviewer (the guy who later crashed in the video that started this discussion). The guy with the “odd Futaba antenna”.
At a full speed dive I had no elevator authority or control, I backed off the power completely and regained elevator control.These are with the upgraded s...
He has a series of 4 MiG videos #4 is the crash.
Notice at the beginning he states he experienced FULL LOSS OF ELEVATOR CONTROL.
Then he proceeds to fly the MiG making the statement about NOT KNOWING WHAT CAUSED the loss of control.
Basically, he flew to see WAZZUP with this plane. He found out in his next video. DOAH!
It seems that he continued flying with an undiagnosed system bug. In a prior video of his, he has a 5000 in the front bay and made a statement, “The CG is good.” His crash video he recanted that statement and moved the battery to the middle bay.
I think we can safely toss this crash aside in regard to future posts. Comments?
-GG
But you may be right. He's the one who may have been flying around with flaps down when going to full throttle. Nevertheless, going up immediately after an "incident" of FULL LOSS is a cavalier methodology.
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Originally posted by HaroldAnderson View Post
This is another slightly better screen shot of the crash. Do those elevators not look to be in full up position all the way to the ground? The image is better than my screen shot if you look at the video frame by frame on YouTube.
Flaps were also deployed at 4:01 in the video just prior to the crash. Not sure if he pulled flaps up prior to the high speed pass or not. I will test the effects of the flaps blanking out elevator control when I have someone that can film for me and the visibility improves. Need blue skies and some altitude. We're grey skies here right now.
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I just went back and looked at the video from the first reported crash and it is obvious the flaps were down. You can see it in the frame by frame before impact.
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Originally posted by PieterO View Post
Hi Xviper, thanks for you reply. By the way, also thanks to the others who replied to my post.
Yesterday, I made another two flights after cleaning the fans. I also heated the lipo's a little bit (to 20°) using the car seat heating. The difference with the troublesome flights in the weekend was huge. No problem at all at take off, much more power.
But since I changed 2 things at the same time... Personally, I think cleaning the fans solved the issue. There was really soooo much grass in it, collected at the stators...
Regarding the heating: I will give it another try when it's colder here. Shouldn't take too long. I will then perform two subsequent flights with cold and preheated lipo's so that I can experience the difference.
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Originally posted by xviper View PostHowever, he does make nice videos and he does sound very professional.
There was this nice case last year of a veteran youtuber refuting the benefits of throttle cut while carrying a 3m FMS fox...Freewing A-10 turbine conversion: http://fb.me/FreewingA10TurbineConversion
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Originally posted by xviper View PostThe second picture is clear but the first one, it's too small and is really hard to see what the ailerons are doing, but if you are right about them being in the full UP position and if he's got flaps down, there may be something to this "flaps blanking out the elevator" deal. We may never know.
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Originally posted by Reaper911 View Post
You can also see clearly at the crash site what looks to be full flap deployment. As you stated xviper, I think this may be blanking out the horz stab.
PS. I'm beginning to wonder now if vector thrust nozzles would save this plane in all these crashes. Might be worth considering over the winter if no concrete answer is found by spring. I have had 2 SebArt Mig 29's with VT and in those planes, the VT can redirect the plane's trajectory even when there is no airflow or control surface effectiveness.
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Originally posted by xviper View PostThat's very clear. However, I'm still trying to think of any circumstance whereby those flaps went that way on impact. I can't think of any at the moment.
PS. I'm beginning to wonder now if vector thrust nozzles would save this plane in all these crashes. Might be worth considering over the winter if no concrete answer is found by spring. I have had 2 SebArt Mig 29's with VT and in those planes, the VT can redirect the plane's trajectory even when there is no airflow or control surface effectiveness.
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