Hi everyone. I am new to RC and would like some advice if possible. I may have mentioned this query slightly in another forum but decided to make a separate post. I am using the following components to test the static thrust of my edf:

1. EDF - Freewing 90mm 1900kv https://www.rc-castle.com/index.php?...roduct_id=8798
2. ESC - Castle Phoenix Edge 200A 32V ESC With 5A BEC https://www.rc-castle.com/index.php?...roduct_id=8798
3. Transmitter - Spektrum DX6I
4. Reciever - Orange 2.4ghz DSM2
5. 6S Battery - It is currently out of my possession, I can't recall the name but it is Chinese.

I omitted the spring-balance set up as that is not particularly related to the problem.

The EDF specifies 4kg of static thrust on the website. However, we were only getting 3.1kg of thrust at full throttle. On a whim, we connected a servo tester and recorded 3.5kg of thrust with the exact setup. This lead me to believe it may be a transmitter issue and not battery/esc related.

I would like to know of two things:
1. Has anyone perhaps encountered a similar scenario, and what did you do to resolve the issue? A user mentioned it could be an endpoint issue btw
2. Is this difference in practical and manufacturer specified edf thrust suspiciously big or is it common in RC?

Thanks

There are many variables that could impact EDF performance. Most of the manufacturers use a constant power supply to test the fan, and these do not suffer from voltage sag. The quality of the battery plays a huge role. You should take the C-rating with a grain of salt. Manufacturers are often overly optimistic and the actual C-rating is around 65% of what's on the label.

Was the fan tested inside an airframe or just the fan by itself? The exhaust nozzle FSA affects thrust output.

Also, make sure you've calibrated the ESC throttle range.

Temperature and humidity also affect test results. Here in Phoenix AZ, some of my jets have trouble taking off from grass when the external temperature is above 100F.

Originally Posted by flanker271

There are many variables that could impact EDF performance. Most of the manufacturers use a constant power supply to test the fan, and these do not suffer from voltage sag. The quality of the battery plays a huge role. You should take the C-rating with a grain of salt. Manufacturers are often overly optimistic and the actual C-rating is around 65% of what's on the label.

Was the fan tested inside an airframe or just the fan by itself? The exhaust nozzle FSA affects thrust output.

Also, make sure you've calibrated the ESC throttle range.

Temperature and humidity also affect test results. Here in Phoenix AZ, some of my jets have trouble taking off from grass when the external temperature is above 100F.

Thanks for the advice, 65% is quite a scary figure

It was just the fan itself

It's actually a university project and we got the ESC from a past project. Not sure if the former user made any changes.

I think the max room temperature was around 80F but it was inside a pretty small room, not sure if that may introduce some issues

Seeing that it made more on a servo tester makes me think you should calibrate your ESCs throttle limits. This will be in your ESCs manual, but most of the time it's setting your transmitter to full power, connecting the battery, waiting for a few beeps and then going to 0 power, then some more beeps.

Second measure the voltage of your battery while you are doing these tests. For a lot of EDF setups you are asking 20C of current from the battery and despite the claimed C numnbers that is a lot for a LiPo, especially if its a cheap one at not-ideal temperatures.

Originally Posted by Johan02

Hi everyone. I am new to RC and would like some advice if possible. I may have mentioned this query slightly in another forum but decided to make a separate post. I am using the following components to test the static thrust of my edf:

1. EDF - Freewing 90mm 1900kv https://www.rc-castle.com/index.php?...roduct_id=8798
2. ESC - Castle Phoenix Edge 200A 32V ESC With 5A BEC https://www.rc-castle.com/index.php?...roduct_id=8798
3. Transmitter - Spektrum DX6I
4. Reciever - Orange 2.4ghz DSM2
5. 6S Battery - It is currently out of my possession, I can't recall the name but it is Chinese.

I omitted the spring-balance set up as that is not particularly related to the problem.



The EDF specifies 4kg of static thrust on the website. However, we were only getting 3.1kg of thrust at full throttle. On a whim, we connected a servo tester and recorded 3.5kg of thrust with the exact setup. This lead me to believe it may be a transmitter issue and not battery/esc related.

I would like to know of two things:
1. Has anyone perhaps encountered a similar scenario, and what did you do to resolve the issue? A user mentioned it could be an endpoint issue btw
2. Is this difference in practical and manufacturer specified edf thrust suspiciously big or is it common in RC?

Thanks

Mate, I told you earlier, never rely on what a salesman pitch tells you!!!
You will never get 4kilo thrust out of 90mm/ 6S set up!!!
Even lot of 90mm 8S set ups struggle to get 4Kg.
I'm currently working on the FW 90mm/6S fitment in one on my latest project, will let you know soon the best thrust I get out of it after lot of modification improvements.

After quick preliminary static th. check I got today only ~ 2.35 kilo with the fully close duck, tho using smaller capacity battery at 90A draw.
With out the duct I used to get 2.7kg at peak after check of my log book, at over 100A current, but the best thrust with this FW set up on 6S, I get is just over 3kg with my one of my "FW/Yak-130". (pic)
So you can totally forget about 4kg.

Q-Freewing 90mm EDF 1900Kv not producing specified thrust.

I got further improvement today after couple more cheater openings for the battery cooling inside the fuse, also using larger capacity battery, the thrust peaked at 2,6 kilos, at static.
It should be plenty for flying it ones airborne, but this model is simply very badly design for EDF, that's why it was never very popular and went off the production in no time with hardly any one flying it these days.

Originally Posted by jofro

Mate, I told you earlier, never rely on what a salesman pitch tells you!!!
You will never get 4kilo thrust out of 90mm/ 6S set up!!!
Even lot of 90mm 8S set ups struggle to get 4Kg.
I'm currently working on the FW 90mm/6S fitment in one on my latest project, will let you know soon the best thrust I get out of it after lot of modification improvements.

Hey, sorry for the posting the question that you answered on a separate thread. I see, honestly my mass is around 2.8kg thats why I was quite hell bent on finding out if 4kg was possible. Thanks

Originally Posted by jofro

Q-Freewing 90mm EDF 1900Kv not producing specified thrust.

I got further improvement today after couple more cheater openings for the battery cooling inside the fuse, also using larger capacity battery, the thrust peaked at 2,6 kilos, at static.
It should be plenty for flying it ones airborne, but this model is simply very badly design for EDF, that's why it was never very popular and went off the production in no time with hardly any one flying it these days.

Thanks for letting me know of your testing. I also noticed that the blades have been hitting against the interior duct which could probably be a reason for the lower thrust. I assume maybe vibrations caused a shift in position.

These looks like normal wear marks when you initially spin up the fan. Does it have these markings when you receive the fan new? They're supposed to dynamically balanced from the factory and should spin free of vibration across all rpm range. When you mount the fan on the test stand, don't overtighten the screws so much that it distorts the plastic housing.

Originally Posted by Johan02

Thanks for letting me know of your testing. I also noticed that the blades have been hitting against the interior duct which could probably be a reason for the lower thrust. I assume maybe vibrations caused a shift in position.

Is that an alloy or composite shroud? All my 90mm FW are alloy. Hard to see from the pic. If its 'plastiky' and the motor isn't correctly set in, there's always a possibility of distortion creating impeller to rub against inner shroud.
I always pay an attention having a motor perfectly tight against the inner walls of the motor mount, in lot of cases requiring some alloy tape as a spacer so it can't wobble under the load. Check the spacing at the rear part of the motor.
Here's the short vid. of my recent check run of 6S FW set up in my 90mm Cougar project. Peaking at 2.7 kg static pull.

2021 1002 215020 005 Heavy wing load sling shooter static dolly check run. (1 min 46 sec)

(Cougar dolly th. check)

Originally Posted by flanker271

These looks like normal wear marks when you initially spin up the fan. Does it have these markings when you receive the fan new? They're supposed to dynamically balanced from the factory and should spin free of vibration across all rpm range. When you mount the fan on the test stand, don't overtighten the screws so much that it distorts the plastic housing.

We could only get hold of a used second hand one. I checked with my other group member and they said these marks were already there, but could have increased now that we tested it

Originally Posted by jofro

Is that an alloy or composite shroud? All my 90mm FW are alloy. Hard to see from the pic. If its 'plastiky' and the motor isn't correctly set in, there's always a possibility of distortion creating impeller to rub against inner shroud.
I always pay an attention having a motor perfectly tight against the inner walls of the motor mount, in lot of cases requiring some alloy tape as a spacer so it can't wobble under the load. Check the spacing at the rear part of the motor.
Here's the short vid. of my recent check run of 6S FW set up in my 90mm Cougar project. Peaking at 2.7 kg static pull.
https://youtu.be/nhON1ue0An4 (Cougar dolly th. check)

Unfortunately its plastic. Are the brown parts wrapped around the motor the spacers?

Nice setup! it looks quite effective

Originally Posted by Johan02

Unfortunately its plastic. Are the brown parts wrapped around the motor the spacers?

Nice setup! it looks quite effective

I use an alloy tape to build up the clearance for perfect firm fit inside the plastic shroud motor mounts. But you can use any tape.

Mercury II 90mm 12S TEST I (1 min 13 sec)