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Extreme Flight 76/83" MXS

Enterprise

Enterprise

150cc
It is the Motrolfly 5335-195kv. Response seemed pretty good. I want to fly it back to back with my 72 extra with hacker A60-6XS and the Gecko 155A to compare. The laser would be not a fair comparison with such a smaller prop.
 
AKfreak

AKfreak

150cc
The Motrolfly 5335-195kv is a beast of a motor. That thing should pull out like no other. I now I love my motrolfly motor, expensive but nice.
 
Aeroplayin

Aeroplayin

70cc twin V2
The DM5335 operates on a different Kv efficiency constant with the 22 inch props, up to the 23x8. More like 86-87%. With the 23x9 and up, it's back to normal at about 82.7 to 84.5%.

This means the Amps will spike up to the next plateau as soon as you go to the 24 inch prop, which you may need if this were an 18 pound plane. You may have to add that much weight in battery capacity to get a decent flight time if you are going to start pulling 125A with a 24x10 instead of 105A with the 22x10 props.

Something to keep in mind when buying and using props. Use only as much prop as you personally need. The 22x10 PJN will pull 32 pounds at 7300 RPMs at 105A. That's way more than a 2-to-1 thrust to weight on this plane, and the same thrust as a 24x10TH Mejzlik spinning 6570 RPMs and pulling 119A. On a plane with a 76 inch fuse, and a real 76 inch wingspan, I would never consider a 24 inch prop. Not sure it can clear it anyway.
 
Enterprise

Enterprise

150cc
I flew it today with the 21x10 Falcon and then the 22x10 APC which was 105A. I checked my recharge and I was pulling 525 mah per minute on the 5300s and I did 625 mah per minute with 3300s. I might have been harder on that flight. CG was only a little better with the 3300s.

At the end of the day I had some strange sounds from the motor, power dropped off and eventually it just dead sticked. Landed with no issues but I have to go diagnose what is up. I think the beta software on the Gecko did the ESC in, but I will not know that till I throw some parts at it. I was playing with the throttle response at the time so that is my first suspect. ESC would not rearm after the flight. I am soldering up the Hobbywing in a few minutes. I just hope the motor is okay. It is spinning, but it has always not been a freewheeling machine with all those magnets. I don't hear any scrapping or other bad sounds.
 
Enterprise

Enterprise

150cc
I just got it running fine with no prop on my Hobbywing ESC. The 100A is probably not enough for this beast. Time to go ESC shopping.
 
Aeroplayin

Aeroplayin

70cc twin V2
Enterprise said:
Just ordered a ICE2 HV 120 off ebay. I have had one before. Time for some logging data. Break out the old castle link.
Click to expand...

Here's a good example of how the measured current and the real current can be significantly different. At only 3.9 volts per cell, you could already be spiking to 120A if the prop is about 120g (?) and spinning to 8000 RPMs, which is about an 86% KvE. You may not see the RPMs, but we know the system will see more volts at some point.

Sometimes we don't see these things because the meter sampling is so slow compared to the switching. But if you calculate the potential using Watts-out (shaft power) it could easily explain it. In this example, it would take 106A just to run the Watts-out, which may only be 80 to 85 percent of the entire power-in.

Even with my A60-7S on 12S with the 20x8, the 69A I see on the meter are low because by the time the Watts meter records the number, I'm already down to 45v, which is only 3.75 volts per cell. What happened when I was still holding 48 volts? The answer is 83A. That's why I have a 95A HV ESC on that setup.

If you have a chance to get the weight of the 23 inch props too, I can fill in the blanks with for the DM5335.
 
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