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Radio Control Forum => Jets => Topic started by: Konrad on April 07, 2017, 11:51:01 AM

Title: Freewing 90mm Impeller Inside Diameter Bores (inrunner vs outrunner)
Post by: Konrad on April 07, 2017, 11:51:01 AM
I’m looking for some information on the Freewing/Changesun 90mm 12 bladed rotor. What is the inside diameter of the 90mm EDF rotor (inrunner and outrunner rotors)?

I’ve recently come back to the EDF part of the hobby. When I left the WeMoTec was the standard by which all other EDF units were measured. We were also using round cells (NiCads). :o It looks like in the last 8 or so years the efficiency of the fan units has dropped noticeably in an effort to get that swish sound. :-\ Combined with the generally less efficient outrunner motor and I’m finding that the EDF systems sold in the entry level foam jet market are rather poor performers. I define performance as power in vs power out.

While I too like the swish sound of the modern EDF rotor, to get any power out of the Freewing/Changesun 90mm 12 bladed rotor takes a huge amount of watts. Unfortunately for us we are limited in the entry market by the cost of the transistors used in the ESC. The cost of transistors that can handle more than 20 volts to 22 volts triple. This is why most entry level EDF are limited to 6cell (22.2v nominal). As a result of this limitation the 6 cell 12 bladed 90mm EDF model needs to draw a battery cooking 110 plus amp draw.

Unlike the OEM (Freewing) which in mainly interested in the cost of entry. I’m mainly interested in the cost of operation. Cooking a $100 set of batteries for 30 3 minute flights in not my idea of a practical EDF set up.  The best way I know to extend the battery life is to cut down on the amp draw. To that end I feel that the 10 cell battery set up is the proper voltage for the 90 mm edf.

As of late I’ve been using the WeMoTec EVO and Jet fan 90mm units to great effect. These rotors are have a much lower rotor load than the Freewing/Changesun 12 bladed rotor and are also noticeably more efficient. Plus they don't whine!

The project jet is a Freewing 90mm F-16 sold with a 6 cell outrunner EDF system.

The idea was to use the stock EDF unit and re-motor it for 10 cell operation. Here is where we hit our snags.  The Freewing 90mm rotor used a questionable non standard proprietary rotor mounting system.  And the outrunner EDF housing uses a rear motor mounting system. Because of the poor motor mounting with the rear cantilevered mount that introduces an overhang ratio of 2.5:1 (or more), the fan housing* has to go into the trash bin. While I don’t like the Freewing rotor mounting system, it allows for mis centering of the rotor with its inherent clearances (a collet system is far superior). It should be safe to at least 2.5 Kilo watts of power.

Wanting to use as many parts as I already had, I was on the Freewing USA importer’s site (MotionRC) looking for a rotor adaptors to use the Freewing/Changesun  
proprietary rotors with higher end motors.

Much to my surprise I find that the rotors are listed as being engine type specific.

Here is where I made my first real mistake. I called MotionRC and asked to talk to a Customer Service Representative (CSR) that was familiar with the 90mm fan units.

At first the CSR tried to sell me on the idea that the inrunner was a much more powerful system. I tried to correct him in saying I wasn’t interested in the EDF system but rather the differences in the rotors. Why had Freewing assigned two different SKU# P9020 and P9021? He came back saying the the inrunner rotor had much stronger blades to harness the power of the inrunner motor. This is blatantly false!  

After some digging on my part, I found the difference in the 90mm rotors in the ID mounting bore. The outrunner rotor had a much smaller ID bore as it pilots on the extended 5mm motor shaft. The inrunner rotor uses a much larger ID bore to allow the mounting adaptor from the inrunner motor to have sufficient wall thickness. The fan blade are identical between both rotors.

This brings to light a problem with this product SKU# P09023
This hardware looks to be only applicable to the motors (rotors) that use the adaptor (grub screwed onto the inrunner motor).
It would also be nice to know what size motor shaft (5mm, 6mm or 8mm) the fan adaptor fits.

I suggested that MotionRC might want to consider a rewrite of your descriptions, as I can only hope there is translation issue between chinese and english. The EDF housing are really defined as front or rear motor mounting. (I’m using a lot of Hyperion/Scorpion outrunners in the Freewing  inrunner housings). MotionRC might also want to give the dimension for the bores in the fan rotors, this is what I’m asking for.

As it stands now MotionRC is leaving a lot of sales opportunities on the table for lack of accurate data, conscientious and technically accurate customer service.

I know just be done with the Freewing EDF unit and run a WeMoTec or JetFan 90mm EDF unit. After cooking your first set of batteries one would be money ahead with the WeMoTec or JetFan!

All the best,

*Freewing/Changesun aren’t stupid. The cantilevered rear mount for the cheap outrunner was done to try to get some effective cooling for outrunners in EDF applications. The outrunner rotor is by nature fighting the natural cooling airflow found in the standard EDF housing.  

Title: Re: Freewing 90mm Impeller Inside Diameter Bores (inrunner vs outrunner)
Post by: Hank G B Z on April 13, 2017, 02:08:18 PM
Interesting stuff Konrad.  I'm not into EDF's that much.  Can you post pictures of the parts you're trying to work with and how it will fit in your F-16.  Converting the F-16 to 10 cells with the wemo tec fan sound pretty neat. 


Title: Re: Freewing 90mm Impeller Inside Diameter Bores (inrunner vs outrunner)
Post by: Konrad on April 13, 2017, 02:35:10 PM
Not my F-16! I'm trying to divest myself from as much of the Freewing/MotionRC product line as I can. It was a fun diversion for 3 years playing with foam beer coolers but they really aren't my idea of modeling. Don't get me wrong there are some nice foam models but they usually start with the name Multiplex.

This is for a project I saw at the flying field (P.C.C.). The poor guy had an F-16 that was marginal on power (by today's standards) but was eating batteries. I opened my big mouth saying I thought I could get the performance and efficiency up. Where I got into trouble was also saying I could do it easily and rather inexpensively. Freewing and MotionRC have made sure that isn't the case with their proprietary EDF system and the total lack of technical support (data) on the sales pages.

As the subject is rather detailed I think some drawing would be more appropriate than blurry washed out photos. I'll try to find some time to draw what the issues are.

All the best,

Title: Re: Freewing 90mm Impeller Inside Diameter Bores (inrunner vs outrunner)
Post by: Hank G B Z on April 13, 2017, 06:46:33 PM

  Yes i thought you were divesting from Motion R/C.  This makes more sense. 

Which club is P.C.C.?  I don't remember all the Bay Area clubs any more.

  Yes Multiplex stuff is nice.  Dad's plugging away at the Fun Cub XL right now.  It's a big model and has lots of well thought out and detailed pieces of hard ware and design features.  It was just the kit no servos or anything like that and cost more than most of the PNP stuff on the Motion RC site.  It's good to remeber you have to buy quality, that is one thing that is never free. 

 A foam Jet I want is an Alfa A-4, but my field is so rough it would last about 2 flights before getting serriously scrapped up on the bottom.  Plus they don't import to the US any more and shippings not cheap either.



Title: Re: Freewing 90mm Impeller Inside Diameter Bores (inrunner vs outrunner)
Post by: Konrad on April 13, 2017, 07:05:29 PM
Peninsula Channel Commanders (P.C.C.)

As for Alfa models I too liked them in the day. Perry still has an A4 on the shelf. Don't think I can stuff a 90mm fan in one.
I've thought of bringing in some, a carton of 4 makes the shipping bearable.

Title: Re: Freewing 90mm Impeller Inside Diameter Bores (inrunner vs outrunner)
Post by: Hank G B Z on April 14, 2017, 11:22:49 AM

  Ok i remeber P.C.C. now.  I flew there once not long after the field was built.  It was a nice field.  I wanted to join the club but you had to go to a meeting in San Mateo on a tuesday and I just never made it. 

  Probably can't put a 90 mm fan in the A-4 but the GP hyperflow fan might work ok.  One thing about alfa models is they are very light.  Carton of 4 makes shipping reasonable...hmm I have a friend who might want to replace a beloved alfa model maybe i can work something out. 

 Speaking of alfa have you seen their new "short kits" Most of it doesn't interest me to much but the La-7 and the macci 202 look neat.  https://www.alfamodel.cz/

now back on topic


Title: Re: Freewing 90mm Impeller Inside Diameter Bores (inrunner vs outrunner)
Post by: Bill G on April 14, 2017, 09:55:24 PM
There's a guy building the LA-7 at that other place now.  Really like it.  I could see getting one, if it were to turn up conveniently on Ebay or something of that nature.  Really like the Bristol M1c also.  Just a bit more appealing than another overdone Horizon Hobby micro P51, F4U, or P47.  It's a shame people like heavy stuff that has to have retracts these days.  The Alfas were the best of the ARF parkflyers.  Sometimes you see idiots ;D who likely have no flight experience, placing wanted ads stating "must have retracks", spelled improperly to boot.  Shave off 50% of the weight, and a model is a LOT easier to fly.

Title: Re: Freewing 90mm Impeller Inside Diameter Bores (inrunner vs outrunner)
Post by: Konrad on April 15, 2017, 12:20:14 PM
Now I'd be the last person to judge one's intelligence by their command of english spelling. ::)

Title: Re: Freewing 90mm Impeller Inside Diameter Bores (inrunner vs outrunner)
Post by: Konrad on August 17, 2017, 10:59:34 AM

Well, I finally was able to look at two Freewing 90mm rotors side by side.
Unfortunately I didn’t have my micrometers with me. But it looks like the inrunner and outrunner rotor hubs have the same through bore. I assume these are 6mm. The difference between the rotors is in the drive pad/flats. Can’t say why they would make a different drive pad, but Freewing (or the OEM) uses various size drive pad.

MotionRC really should state what is different in the component descriptions. Saying things like fit outrunner vs inrunner real doesn’t help in the selection process. They are running into this problem with the 80mm fan as the newest outrunner motor 1800Kv uses a different drive pad from the earlier outrunner motor. https://www.motionrc.com/collections/motors/products/freewing-3530-1800kv-brushless-outrunner-motor-mo035302#reviews-tab

Same issue with their retracts calling a unit an “A”, “B”, or “C” type tells us nothing as to the configuration. Is the type a rotating pin or what is the strut pin size? It might be nice if Freewing/MotionRC provided a Rosetta  Stone (chart) to decipher their coding.

Title: Re: Freewing 90mm Impeller Inside Diameter Bores (inrunner vs outrunner)
Post by: Hank G B Z on August 22, 2017, 01:09:12 PM

   interesting stuff.  I agree that it would be way better to have all the impellers fit all the types of motors and just change the collets or what ever you want to use to mount them to the motors. 

   As for retracts, i think they should be listed by the physical size of the unit and the designed gross weight.  get rid of the .40-.60 size or "A" , "B" etc.  Unfortunately the current modeling public won't take the time to find the better answer they want simple terms. 

The struggle continues