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Jan 26, 2020, 01:48 AM
Dont confuse me with the facts
Quote:
Originally Posted by MarkF
So the ID is 130mm and the od of the motor tube is 60mm. What's my exit size on the thrust tube? I want to play with chocking it down.
What is the OD of your spinner in front and the OD of your impeller? Knowing that would be more useful then the OD of the motor tube and the ID of your shroud for figuring FSA and optimal exhaust diameter. Though it very well may end about the same.

Scott
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Jan 26, 2020, 02:00 AM
Classic jets rule
AIR SALLY's Avatar
I do know that when i put JF 120' in my nacelle i had to cut just over an inch off the back so the ehaust was 4.100" but that was only about a 11" long...so thats a 120mm fan .
Jan 26, 2020, 04:00 AM
Registered User
Quote:
Originally Posted by MarkF
No he doesn't. There's very little info for this fan on his website. I hope he sees this thread has come back to life and answers some questions.
Interesting... did this fan/motor system ever live up the expectations from page one?
Jan 26, 2020, 06:43 PM
Battery Puffer
Since I just got the fan a week ago it's going to take a little while before we know anything. The fan has successfully flown several big jets from the videos I've seen so I have faith.
Jan 26, 2020, 06:45 PM
Battery Puffer
The front spinner is 41mm.
Last edited by MarkF; Jan 26, 2020 at 07:48 PM.
Jan 27, 2020, 09:42 AM
Lee Liddle
Knife Liddle's Avatar
based on the 120mm, the JF doesn't take to choking down the exhaust very well, probably because it doesn't have the blade coverage of the Dynamax.
I'd guesstimate that anything below 90% would not be good. Even the 120mm doesn't like anything below 100mm for the exhaust diameter.

I like the JF products I'm sure that it will do well and will have a sweet spot for exhaust dia at the power level you're shooting for
Jan 27, 2020, 12:35 PM
Dont confuse me with the facts
Quote:
Originally Posted by MarkF
The front spinner is 41mm.
Quote:
Originally Posted by MarkF
So the ID is 130mm and the od of the motor tube is 60mm. What's my exit size on the thrust tube? I want to play with chocking it down.

My notes on the JF120Eco are 120.19mm ID and 119.0mm for impeller diameter. So lets assume 130.19mm ID and 129.0mm impeller for the JF130P. Knowing the spinner OD allows us to get the FSA: 117.496cm^2 This would be a diameter of about 122.311mm.
% of FSA:
100=122.311mm=4.815in
95=119.214mm=4.693in
90=116.034mm=4.568in
85=112.765mm=4.440in
80=109.398mm=4.307in

Quote:
Originally Posted by AIR SALLY
I do know that when i put JF 120' in my nacelle i had to cut just over an inch off the back so the ehaust was 4.100" but that was only about a 11" long...so thats a 120mm fan .
The FSA is different on the ECO and PRO variants. So between that and Reynolds numbers, I can not say for sure how to translate the 104.14mm provided by AIR SALLY.

For the JF120Eco, Rainer suggested 100-105mm exhaust diameter. That would be 86.3-95.1% of FSA.

I hope this helps dial it in a little more for you. Perhaps Rainer can chime in about the Pro variants and the 130mm spicificly.

Scott
Jan 27, 2020, 01:08 PM
Registered User
demetrius's Avatar
Quote:
Originally Posted by MarkF
I got the motor in and installed it on the fan. The total weight is 1630g for motor and fan.
That's the Jetfan 130?
Latest blog entry: "Is that a Turbine?" Not...
Jan 27, 2020, 02:24 PM
Dont confuse me with the facts
Quote:
Originally Posted by demetrius
That's the Jetfan 130?
The JF130Pro, so yes.

Scott
Jan 27, 2020, 02:28 PM
Battery Puffer
The rotor would be 128mm
Jan 27, 2020, 11:04 PM
Registered User
70 ragtop's Avatar
I don't think you would use the spinner diameter, but the hub diameter on the motor side
Jan 28, 2020, 12:13 AM
Dont confuse me with the facts
Quote:
Originally Posted by 70 ragtop
I don't think you would use the spinner diameter, but the hub diameter on the motor side
If you define it by the minimum surface area the air has to go through, than you may be right. However, manufacturers do not give different FSA numbers for different motors. A given fan does not generally need a different exhaust diameter because of a different diameter motor. A bigger motor would add back pressure needing a larger exhaust diameter to relieve some back pressure to have equal back pressure to the smaller diameter motor, if all things are equal. That means the smaller FSA of the two would really need the larger exhaust diameter. That is counter intuitive. I posit that an impeller blade coming out of a truncated cone will bring in more air than one that had a blade coming out of a cylinder with a diameter that is the same as the largest part of said truncated cone. Therefor, for all practical reasons, it has a greater FSA. Perhaps a diameter between the too, but closer to the front would be best. In any case Rainer said, if I remember right, that the PRO has greater FSA than the ECO. So if we are going to compare the JF130PRO to JF120ECO figures, than we must compensate for the change in design. That change can be represented by using the spinner diameter (or a little behind it) instead of the hub diameter. Thus, attempt to turn an orange into an apple that we may compare apples to apples. That is why I mentioned the spinner. I am open to the possibility that I could be in error. I will use the spot 2/5 from the spinner to the hub in future calculations.

Scott
Jan 28, 2020, 12:46 AM
Battery Puffer
The motor is 56mm but the heat sink is 60mm and part of the fan design. Although it's possible to mount the motor without it, but I figure it was designed to be used so it's on. Plus it doesn't look any bigger than the hub holding the blades in. I wish Rainer would pop in here and help answer some questions.
Jan 28, 2020, 12:59 AM
Dont confuse me with the facts
Quote:
Originally Posted by MarkF
The front spinner is 41mm.
Quote:
Originally Posted by MarkF
So...the motor tube is 60mm. What's my exit size on the thrust tube? I want to play with chocking it down.
Quote:
Originally Posted by MarkF
The rotor would be 128mm
I will use 2/5 from spinner to hub of the truncated cone the impeller blades come out of along with the new 128mm rotor given, to figure FSA.

FSA=110.129cm^2
% of FSA:
100=118.4mm=4.66in
95=115.4mm=4.54iin
90=112.3mm=4.42in
85=109.2mm=4.30in
80=105.9mm=4.17in

Using the 60mm and the new provided 128mm measurement goes as follows.

FSA=100.405cm^2
% of FSA:
100=113.1mm=4.45in
95=110.2mm=4.34in
90=107.3mm=4.22in
85=104.24mm=4.10in
80=101.1mm=3.98in

Quote:
Originally Posted by Scottfpv
For the JF120Eco, Rainer suggested 100-105mm exhaust diameter. That would be 86.3-95.1% of FSA.

I hope this helps dial it in a little more for you. Perhaps Rainer can chime in about the Pro variants and the 130mm spicificly.
110mm and 4.33in seems safe don't matter how you look at it.

Scott
Jan 28, 2020, 01:01 AM
Battery Puffer
I just sent him a PM asking him to come on here.


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