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Old Dec 19, 2012, 08:25 PM
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Originally Posted by db_sonic View Post
Good point on the stators. I often wondered about the AOA and shape necessary to match up to a given rotor. And then how many is ideal? It seems like the shroud and stator design is as important as the rotor itself.
Yeap...I think that's why dynamax has the best compromise design of all the fans...tons of stators to spin the air and make it easier to flow through a tube ...my guess.

I mentioned this in another thread that I don't think EDFs are getting the best efficiency bang for the buck cause they've only been used in a wide numbers here in the last 5 years where as turbines have had almost 100 years of use and trial and error.
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Old Dec 19, 2012, 10:56 PM
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Originally Posted by erh7771 View Post
Yeap...I think that's why dynamax has the best compromise design of all the fans...tons of stators to spin the air and make it easier to flow through a tube ...my guess.

I mentioned this in another thread that I don't think EDFs are getting the best efficiency bang for the buck cause they've only been used in a wide numbers here in the last 5 years where as turbines have had almost 100 years of use and trial and error.
actually erh the stators job is to unwind the air or straighten it out, the rotor spins the air and the stators straighten it out more thrust is gained from air that is moving in a straight line.
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Old Dec 19, 2012, 11:12 PM
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Originally Posted by jcdfrd View Post
actually erh the stators job is to unwind the air or straighten it out, the rotor spins the air and the stators straighten it out more thrust is gained from air that is moving in a straight line.
Thx...I was thinking I read some time ago that some removed dynamax fans stators to get more thrust but maybe that was without a thrust tube or some other variable.

There's a turbine engineer in the other thread that mentioned GE went through a lot of trial and error.

I was thinkin of using the smoke system to do some air tunnel testing or as close to what I can call it on fans would love to see how the air moves through the shroud
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Old Dec 19, 2012, 11:16 PM
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either that or mini-streamers taped inside the clear mylar thrust tube at various lengths down the tube and around it fully. Could be fun on a rainy day.

PS agree on the dynamax. I didnt know how many it actually had, it's quite a few.
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Old Dec 19, 2012, 11:33 PM
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Originally Posted by erh7771 View Post
Thx...I was thinking I read some time ago that some removed dynamax fans stators to get more thrust but maybe that was without a thrust tube or some other variable.

There's a turbine engineer in the other thread that mentioned GE went through a lot of trial and error.

I was thinkin of using the smoke system to do some air tunnel testing or as close to what I can call it on fans would love to see how the air moves through the shroud
I think more stators straighten the air sooner and more efficiently, however they have to be designed so that the rotor angle and stator angles complement each other at a given rpm or airflow.

ya the smoke idea came to me as I was responding to the last post you made lol!!! take your smoke system and put it front of an edf of choice and lets see what the air is doing.....I love stuff like this.....make a vid I want to see that
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Old Dec 31, 2012, 10:17 PM
Keith Thomas
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I have my head so messed up with what motor to run. I was all set to try a HET 700-98-670 kv motor then I read that It will be to much but it looks like the next one in line the HET 700-98 520 is to low to run on 12s.

I really am uncomfortable trying to change the Scorpion shaft.....My question is, is there a motor that has the 8m shaft that will have the right kv to run on 12s?

Thanks, and thanks to erh7771 for all your work and help.
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Old Dec 31, 2012, 10:46 PM
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keithtsr, Have you considered the HET 800 series? The 800-73-590 sounds like the sweet spot. I have one of these motors and they are sweet.

Dean
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Old Dec 31, 2012, 11:08 PM
Keith Thomas
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Hey Buckaroo, I have but I can't find the motor anywhere. I spent the day going over which motor, erh has been a big help. Where do I find the 800 motor?
Thanks
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Old Jan 01, 2013, 09:25 AM
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keithtsr:

HET 800 series motor is here:
http://www.highendrc.com/index_ecat.php?cPath=63

You can look thru the different series and find a motor with the KV that you think is closest to what you want. FYI, the series number is the length of the motor case.

A friend of mine and I have been flying the 800-73 series motor (590)KV in a Byron's F-16 with the stock Byron fan and rotor. Performance is great and reliability of the motor is not a problem

A number of us in my club have been flying the HET series of motors (both 700 and 800) and they work very well. No problems. Really nice motors for the price.

Ed
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Old Jan 01, 2013, 10:33 AM
Keith Thomas
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Thanks A10. I'm putting the CS fan in a Byron Mig 15. I thought about using the Byron fan but I really like the sound of the CS and of course the challenge.
KT
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Old Jan 01, 2013, 03:25 PM
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Sounds interesting keithtsr. I think the big HET will be a good choice. let us know how it goes.

Ed, I sent you a pm a while back. It sounds like the F-16 is going well. Did your mods to the housing help? I have my Eagle ready to go with the same motor. I couldn't remove the housing so I made it a pusher. Your test numbers are promising. What collet did you end up using. I ended up getting a TruTurn stainless collet and it seems to be real nice. I had to put sandpaper wedges between the rotor and collet spacer just to tighten it up. No good way to hold the shaft on the motor. But I got it pretty tight. Are you using a clamp type collet and if so did you sand the shaft at all before running it? Are you noticing any concerns running almost 24,000?

Dean
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Old Jan 02, 2013, 09:25 AM
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Dean:

I am sorry, I never saw the PM. I apologize. F-16 is doing well. I think the mods (putting carbon fiber mat in all of the radii where the stators meet the center body and the outer shroud). I have taken a cursory look and it looks like all is holding up well. I tried a number of different collets that I had laying around and I finally settled on the Great Planes compression collet (P/N GPMQ4971). It fits the HET 800 8mm motor shaft very well. I did not sand the motor shaft. I just tightened the nut and all is well. The nice thing about the GP collett is that the "prop shaft" is 3/8 x 24 and it is a good fit into the Byron rotor. I have added a couple of photos of the mods and the "motor mount". The mount is a balsa/carbon sandwich. I had some 1/4" end grain balsa and I sandwiched it with some carbon mat that I had. The first photo is of the balsa/carbon mount. I glued it into the shroud (after roughing the center body with sand paper) using Hysol (you could also use a good structural epoxy glue). The second photo is nothing more that a shot of the rotor mounted to the GP prop adapter. The last photo is not something I can not take credit for. A friend of mine sent me a spinner to try. It is a 2 1/4" spinner with no prop slots. Into the tip of the spinner he glued a nut that screws to the end of the prop adapter and it looks promising. The nut was glued into the front of the spinner using Bob Violett V poxy (but you could use Hysol or similar structural epxoy). I have not run this spinner at any high RPM as of yet so I can not comment on its structural integrity. If you choose not to glue the nut to the spinner, then use an adapter (as we now do for porp planes) to attach the spinner to the prop adapter. I would not use a regular epoxy as I think the structural stuff is better. For a very long time I have been using s structural epxoy called T-88. It is made by System Three (www.systemthree.com). In fact about the only epoxies I use are their stuff. They have regular epoxy and they have an epoxy called Clear Coat that I use for applying glass cloth to my sheeted wings/tails. It is really nice as it has the viscosity of the old modeling lear dope. Works very well

KT:

I understand the sound issue. I am not really a fan of the sound but having had a CS 120mm fan and rotor expolde while testing on my test stand, I am not a "fan" of their fan. So, I just went with a stock unit. I have not noticed any issues with running the rotor at 24K, however, I know that they were NEVER designed to turn that kind of RPM. I am trying to finish a Byron Mig 15 and it will have the same power system in it so I hope if we get more time on the setup we will find any issues.

Hope this has been helpful.
Ed
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Old Jan 02, 2013, 10:54 AM
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Hi Ed, good to hear from you. I thought you might have missed my pm. No problem there. Very interesting stuff. Thanks for the links on the epoxy. The laminating type sounds really cool and I will check it out.

Good info on your Byron fan. I will keep you posted via pm on my Byron conversion. I havn't run it yet but I will soon. As far as I know we are the only ones running the new HET and your set up at close to 24,000 is the highest rpm I have yet seen reported. Real nice.

Dean
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Old Jan 02, 2013, 11:57 AM
Keith Thomas
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Ed,
Thanks for the input. I am a little nervous about the CS fan but I think with err help I pretty sure that it will hold up.... pretty sure. I have a blast shield left over from my Liddle fan.lol

I got a bit ahead of myself and ordered a 700-98-520 any thoughts on running this in a CS fan or is there another fan this will work in. I really want to stay with 12s. I did go ahead and order a 800 motor as well.


Thanks,
KT
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Old Jan 02, 2013, 01:07 PM
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Originally Posted by keithtsr View Post
Ed,
Thanks for the input. I am a little nervous about the CS fan but I think with err help I pretty sure that it will hold up.... pretty sure. I have a blast shield left over from my Liddle fan.lol

I got a bit ahead of myself and ordered a 700-98-520 any thoughts on running this in a CS fan or is there another fan this will work in. I really want to stay with 12s. I did go ahead and order a 800 motor as well.


Thanks,
KT
I am running sk3 700-560kv motors in all my cs's but it requires some work, I changed out the shafts, and turned down cooling fins a little, and it works great. Lots of work though
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