Tiger-Motors U8 + 28x9,2 props


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Cameraj

Member
I have issues with my larger x8 of altitude loss in forward flight with dji wkm, my friend told me gryphon dynamics uses naza v2 and know more altitude drop, so strange
 

FerdinandK

FerdinandK

Member
The more you are close to the power limit of the copter, the more you have "altitude loss" problems in forward flight. Also I assume you have a cam underneath you copter, I would try to place the batteries a litte bit more up and/or foreward, even to move the CG a few cm towards the nose of the copter this will reduce the problem.

best regards
Ferdinand
 

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Cameraj

Member
Thanks so much for the info, i will give it a try. i have the batteries on the top almost centered with the imu in between them. with avroto 3520 400kv and 16in props my auw is only 22lbs. i should be good with power?
 

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matt.koestner

Member
Cameraj said:
I have issues with my larger x8 of altitude loss in forward flight with dji wkm, my friend told me gryphon dynamics uses naza v2 and know more altitude drop, so strange
Click to expand...
One thing I found with the DJI motor mixsr is that all the top props spin one way and all bottoms the opposite. On the A2 I have configured them the same way as APM copter which has solved all of my altitude loss with big x8 frames. The WKM manual has all the info on the custom motor mixer setup. Obviously as others have said you must have the thrust overhead available for the aircraft to be able to do what you are asking of it.

Sent from my SM-T350 using Tapatalk
 



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Luc Maximilien

Member
Hi everyone,
Ferdinand , your datas , 6,1kg (4,2kg battery 1,9kgcopter) for 151' 30" seconds flight with 28" propellers , shows an lower efficiency compared to the one claim on Foxtech site for his 8108 motor (that I guess is very similar to T-motor U8 ) .

If my maths are not wrong you hover with 428watt,19A, 4,8A each rmotor and an efficiency of 14,2gr/watt while according to Foxtech graph (https://www.foxtechfpv.com/foxtech-motor-8108.html) you should fly with 3,6A per motor , 14,5 A total , 19gr/watt and a flightime of 198 minutes.
It a really big difference between what is claim by manufacturer and the reality .

I have bad experience with untruthful performance data with T-Motor 4004 , 20% less than promised, but it seems that it is bad habit of chinese manufacturers.

Since I was starting a project with 28" props based on T-Motor and Foxtech performance data your opinion about would be greatly appreciated.
 

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Luc Maximilien

Member
R_Lefebvre said:
...
I've got a helicopter I'm working on designed for work (not endurance tests) that is flying 50 minutes with 1kg payload, so far my best distance is 40km. That's using Turnigy Multistar batteries. So could go quite a bit further with higher energy density.
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Hi R_Levebre,
What is the AUW of your heli with 1kg payload and 50 minutes flightime ?
What is the battery capacity ?
My best flightime with a hexa copter for work (foldable, water resistant ) and 1 kg payload is 43' , with 21600mAh 4S batteries but the suggested batteries are 14400mAh 4S for 36'.
 

FerdinandK

FerdinandK

Member
Luc Maximilien said:
Hi everyone,
Ferdinand , your datas , 6,1kg (4,2kg battery 1,9kgcopter) for 151' 30" seconds flight with 28" propellers , shows an lower efficiency compared to the one claim on Foxtech site for his 8108 motor (that I guess is very similar to T-motor U8 ) .

If my maths are not wrong you hover with 428watt,19A, 4,8A each rmotor and an efficiency of 14,2gr/watt while according to Foxtech graph (https://www.foxtechfpv.com/foxtech-motor-8108.html) you should fly with 3,6A per motor , 14,5 A total , 19gr/watt and a flightime of 198 minutes.
It a really big difference between what is claim by manufacturer and the reality .

I have bad experience with untruthful performance data with T-Motor 4004 , 20% less than promised, but it seems that it is bad habit of chinese manufacturers.

Since I was starting a project with 28" props based on T-Motor and Foxtech performance data your opinion about would be greatly appreciated.
Click to expand...
From my point of view, eta comes from propellers not from motors. The graph on the web-page shows the falcon 28" propellers, so possibly they are that good. That would be really great, since according to their data, you could add 1kg payload and still fly for 151 min.
A number on a web-page is a number on a web-page, your copter does not even fly for one more minute, because of a number on a web page.

best regards
Ferdinand
 

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Luc Maximilien

Member
Hi Ferdinand ,
I agree , you are absolutely right .
I follow your work since a long time and I know how much effort you invest in it, my compliments .
I just wanted a confirmation that once again RC manufacturers are unfair giving untrue performance data .

With a lighter battery pack, let say 24000 mAh 6S, your flight time should be around 40 minutes, can you confirm ?
This information would help to calculated the motor-prop combination efficiency precisely, an invaluable information for your followers :)

Best regards
Luc Maximilien
 





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