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Old Sep 14, 2011, 02:09 AM
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Build finished (almost) no problems!

Finally I managed to get my build done
I must say that I am still very pleased after the first static tests.

- no servo jitter, no creeping
- Gyro works perfect after adjusting the gain

Only one issue, one of the elevator rudder horns broke when I tried to snap in the pushrod. The plastic is of bad quality, I need to buy new ones before I can fly on the WE.

I included end-to-end telemetry to get some facts behind the ESC temperature discussion. Therefore I am using the brand new UNILOG2 with 2 temp sensors attached. This allows me to track the temp of both ESCs, the airspeed, altitude, the current, capacity consumed, the voltage and the voltage of each single cell in the pack during flight in realtime. All data is displayed on my Tx and recorded on a memory card in parallel.

As you can see on the pic I also added 660 uF additional capacitors in the power lines to cope with the long wires and the high current.

Results of static testing (see video attached):
- after in total 2800 mAh capacity consumtion at several full throttle bursts over 10 min the ESC temp did not exceed 38 deg Celsius on any of the 2 ESCs. (outside temp was 18 deg Celsius)
- max current was around 103 A (~112 A in the very beginning with fresh loaded batteries)

I assume current will go slightly up after a few load cycles (I used a brand new Nanotech 45/90 4000) and when I pre-heat the battery.

Conclusion so far: I cant see an issue with the plane. As long as the ESC stays below a 100 deg Celsius, things should be fine. In flight temp will be likely even less than on the ground.

If weather permits, I will maiden it on the WE and post detailed log files, documenting temp and current during flight. If there is a problem, we will then have some real evidence.

Best
Stephan
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Old Sep 14, 2011, 03:26 AM
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... and here is the video from my tests today.

MIG29 Sebart (2 min 18 sec)
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Old Sep 14, 2011, 04:24 AM
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Joined Dec 2008
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Hello Stephan,

thanks for posting the tests. And it is interesting to hear what your temperature sensors will sense. As far as I know, others including me used telemetry in the MiG only for current measurements.

Quote:
Originally Posted by schiwo1 View Post
- max current was around 103 A (~112 A in the very beginning with fresh loaded batteries)

I assume current will go slightly up after a few load cycles (I used a brand new Nanotech 45/90 4000) and when I pre-heat the battery.

Conclusion so far: I cant see an issue with the plane.
I am a bit surprised about your conclusion. You have a plane that is specified with 2x45A ESCs = max 90A current. You already measured 103 to 112 A and expect even slightly higher currents. So you measured and now know that you are operating the plane outside the design envelope of its electronics. How can you conclude from your data that you don't have an issue? Your data strongly suggest that you will have an electronics failure in the near future, that should make you afraid. You have to ignore your data in order to come to your conclusion.

Cheers,
Henrik
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Old Sep 14, 2011, 06:25 AM
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Miramar, Florida
Joined Jul 2007
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Originally Posted by fredmdbud View Post
Very nice! And you landed on blacktop!
Yes, if the pavement is smooth (not like concrete roughed up like they do for better grip) the skids seem fine. In fact, landing on grass is how we broke the nose, concrete seemed to be no issue...

Jack
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Old Sep 14, 2011, 06:26 AM
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Very interesting thread .
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Old Sep 14, 2011, 06:34 AM
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Miramar, Florida
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Quote:
Originally Posted by schiwo1 View Post
Finally I managed to get my build done
I must say that I am still very pleased after the first static tests.

- no servo jitter, no creeping
- Gyro works perfect after adjusting the gain

Only one issue, one of the elevator rudder horns broke when I tried to snap in the pushrod. The plastic is of bad quality, I need to buy new ones before I can fly on the WE.
Yes, I had the same issue, seems the plastic is brittle. I fixed mine though, I took a piece of thin poly ply and doubled the horn, then used a dremel to cut it to match the shape of the horn. I then drilled a hole and there you have it, a working horn again!

Quote:
Originally Posted by schiwo1 View Post
I included end-to-end telemetry to get some facts behind the ESC temperature discussion.
Great idea! I also don't see an overheating issue but maybe some have different settings on the ESC's? I don't want to tell anyone they are "wrong" because I also know the amp draw at WOT does exceed the rating of the ESC's, I got a measurement of 119 amps using a fully charged Thunder Power 65C 4400 mAh pack.

Quote:
Originally Posted by schiwo1 View Post
Conclusion so far: I cant see an issue with the plane. As long as the ESC stays below a 100 deg Celsius, things should be fine. In flight temp will be likely even less than on the ground.
You should make sure to hover some, to get an accurate temperature, not just fly around like a regular jet...

Good luck!

Jack
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Old Sep 14, 2011, 07:00 AM
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Miramar, Florida
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Quote:
Originally Posted by hklagges View Post
I am a bit surprised about your conclusion. You have a plane that is specified with 2x45A ESCs = max 90A current. You already measured 103 to 112 A and expect even slightly higher currents. So you measured and now know that you are operating the plane outside the design envelope of its electronics. How can you conclude from your data that you don't have an issue? Your data strongly suggest that you will have an electronics failure in the near future, that should make you afraid. You have to ignore your data in order to come to your conclusion.

Cheers,
Henrik
I measured 119 amps with a 65C Thunder Power 4400 mAh pack but that was static, I don't know what the amp draw is in-flight. And before anyone jumps on me and tells me static should match in-flight WOT amps at hover, yes BUT this thing hovers at half throttle so no one will hover at 119 amps, this would be a strong pull-out from a hover and even then only at WOT, which isn't necessary. I am not calling anyone a liar or saying you are wrong for being concerned but let's wait and see the in-flight amp draw, especially when hovering before concluding the plane is mostly operating outside the specs...

Jack
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Old Sep 14, 2011, 07:06 AM
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Originally Posted by jfetter View Post
I measured 119 amps with a 65C Thunder Power 4400 mAh pack but that was static, I don't know what the amp draw is in-flight. And before anyone jumps on me and tells me static should match in-flight WOT amps at hover, yes BUT this thing hovers at half throttle so no one will hover at 119 amps, this would be a strong pull-out from a hover and even then only at WOT, which isn't necessary. I am not calling anyone a liar or saying you are wrong for being concerned but let's wait and see the in-flight amp draw, especially when hovering before concluding the plane is mostly operating outside the specs...

Jack
EDF don't decrease much the AMPs on the air compared on static.

Actually some can even increase AMPs, since on the air at speed get more "air" in the EDF, so it can get even more work. Like a propeller with high pitch on air at speed increase the AMPs

Tchuss

e_lm_70

ps: It is always a good rule to have ESC capable to handle more then WOT ... what you try to point out is a bad way to save few $ for risk big $ in case of crash.

pps: I can see 80amp ESC for less then 20$, so this saving on ESC is ridiculous .... guess SebArt will fix it soon.
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Old Sep 14, 2011, 07:50 AM
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powder springs georgia
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Wow.. a lot of great info today...In flight info should be REAL interesting...

Jack.. what a flight...You need to go with Jason to demo this bird...You look better than Jason sorry Jason

I do wish you had done the first vid without music...sorry...it was a beautiful vid... but I wanted to hear the motors and what it took at different flight modes...like glide mode and low throttle...
So...You have really not said...Are you happy, very happy..extremely happy with the performance and flight???
I do not think we could have have any better coverage on this bird...How to fly it and real time flight info. to come...can not wait for that.
What a radio with all that info in your face how do you fly???
Thats a huge radio......and the throttle is on the wrong side
Thanks guys...
sanford
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Old Sep 14, 2011, 08:03 AM
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Quote:
Originally Posted by e_lm_70 View Post
EDF don't decrease much the AMPs on the air compared on static.

Actually some can even increase AMPs, since on the air at speed get more "air" in the EDF, so it can get even more work. Like a propeller with high pitch on air at speed increase the AMPs

Tchuss

e_lm_70

ps: It is always a good rule to have ESC capable to handle more then WOT ... what you try to point out is a bad way to save few $ for risk big $ in case of crash.

pps: I can see 80amp ESC for less then 20$, so this saving on ESC is ridiculous .... guess SebArt will fix it soon.
You can guess all day long, I operate on data, not speculation. While you could ask for higher rated ESC's, I'll wait and see the numbers before stating this must happen. Again, I have two of these Migs and I don't see any signs of failure (do you have one?). Do I wish they were over-rated, sure but I also go with what works. So as I said, let's see the numbers first!

Jack
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Old Sep 14, 2011, 08:05 AM
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Originally Posted by sanman55 View Post
Wow.. a lot of great info today...In flight info should be REAL interesting...

Jack.. what a flight...You need to go with Jason to demo this bird...You look better than Jason sorry Jason
I wasn't the pilot (the pilot was a pro)! I was the one shooting video. Jason hovers this thing better than anyone I have seen fly it, no doubt!

If you want to hear the fan I can remove the sound track, you will be surprised by the throttle settings...

Jack
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Old Sep 14, 2011, 08:18 AM
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Quote:
Originally Posted by sanman55 View Post
So...You have really not said...Are you happy, very happy..extremely happy with the performance and flight???

sanford
I was waiting for the in-flight data to make my ultimate conclusion but I am very pleased so far. Not to discredit anyone else, I know Henrik has been through the ringer on this one but I am seeing a fairly well engineered plane with room for improvments (of course) but one designed to do exactly what Seba wanted to do that does it. Did the manufacturer swap some components without telling the designer and we are seeing issues because of it, did Seba know, does he know now and is acting on it? This is all speculation, I can only operate on hard data. All we can do is provide feedback to the manufacturer (through Thunder Power IMO) and see what happens.

Pro's:
+ Fast!
+ Powerful!
+ Flys great!
+ Designed to do 3D, it does this perfectly.
+ Perfect paint and appearance.
+ Nice servos, perfectly suited for this purpose.
+ Vectoring hardware works perfectly and is designed for some abuse.
+ Skids are well designed, not flat on bottom but rounded (curved) which prevents them from wearing down all at once.
+ Easy to build.

Con's:
- Amp draw is high, could use beefier ESC's IF in-flight data confirms!
- Plastic horns and clevises are brittle, should use nylon.
- Foam nose breaks off easily, should use plastic or magnetic catch.
- Gyro is questionable, I actually prefer to hover without but clearly it could be a better quality gyro.
- Programming is tough (not Seba's fault, it is exacty what is required to pull this off). They probably should warn novices or users without programmable radios (with 7 mixes) that they will have issues.

Jack
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Old Sep 14, 2011, 09:12 AM
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Great video Jack!

The Mig looks awesome in the air. Thanks for posting.
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Old Sep 14, 2011, 10:47 AM
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powder springs georgia
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Quote:
Originally Posted by jfetter View Post
I wasn't the pilot (the pilot was a pro)! I was the one shooting video. Jason hovers this thing better than anyone I have seen fly it, no doubt!

If you want to hear the fan I can remove the sound track, you will be surprised by the throttle settings...

Jack
I would love to hear the fans if you could do that..it would show where the power is and what it takes to fly this bird...Both did an excellent job on the video..Great pilot and very nice video...good job..
Does it glide nicely now.??..after you did your trim settings...
Thanks for your insightful info...
sanford.
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Old Sep 14, 2011, 11:05 AM
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You ought to contact sebart and let them use that video..That is by far the best video I have seen on this bird..The sky was great ....I just re-watched it again and it got me going...
Any info you care to share on the pilot and his experience...He did such a good job and at least should have his name out there
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