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Old Apr 10, 2012, 03:06 PM
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Originally Posted by SteveC68 View Post
I don't know if Peter has an EDO F-15 or not, but if it is it isn't 70% FSA, more like 150% FSA. Thomas used the stock exhaust on his and I used slightly larger on mine, but both worked equally as well. I did round the intakes on mine as can be seen in one of the pics in the thread I linked to, but I didn't round them correctly. Based on Peter's measurements the intakes are 4620mm squared. 100%FSA is close to 3000mm squared for the CS fan based on a 69mm diameter and a 32mm hub.
well he said it was a 64mm F15 here
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Yeah, I had thought that explanation in my "Sitting in chair pondering the problem" time a little while ago. LOL. It is a 64mm F-15 and the exit side looks a good area/volume really - I need to do some measuring and maths on it, LOL.
and if you take his measurements and calculate them out his 37mm exits are right around 72%fsa. if the intakes are indeed at 100%fsa that would be great just round the lip and your done with those, bring the exhaust exits up to around 85%fsa 39.5mm and he's good to go.
on a side note we had big thrust losses when we reduced the single exit of our Habu to below 80%fsa with this cs70/10 on a hot 6s setup
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Old Apr 10, 2012, 03:33 PM
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Originally Posted by Thomas Nelson View Post
Tell you what.

I'll retest the DS-30 in my F-15 with the packs I'm using today. Then I'll pull the Schubeler out of my F-15. I'll pull the ESC out of my F-35. I'll install my 450 watt CS-10 setup in my F-15. Then I'll retest on the same re-charged pack, preheated to the same temp. And I'll report back tonight, assuming no other priorities pop up, that is.

I'll do a before/after test too, comparing the two setups in the same plane, and the two setups out of the same plane. Might have to fudge an inlet for the DS though ... I hope one of my several brands of lips can be made to work. If I recall, each draws approx the same power out of the airframe, but I'll verify that.

I'm curious if the 10 blades of the CS will perform differently from the 3 blades of the DS in the same 2:1:2 airframe.

Requests? Anything else I should do while I'm at it? I'll try to catch a bit of vid here and there if I have time. My wife will LOVE hearing the scream of the DS-30 again. Such an obnoxious sound! The worst sounding 70mm fan vs the best.

A bit of work, but in fairness I always meant to install the CS 10 in that airframe anyway. Good excuse to make it happen.

tn
cool that should be a fun experiment
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Old Apr 10, 2012, 05:56 PM
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Steve and Thomas... I would say it is that same plane. But it is the all moving tailplane version, and I recall something about the blurb for it said 64mm but it really was a 70mm. Though I never even checked that... I just pulled it out and it looked quite low power (motor and fan strength). I will have to find where I put that and check it out!

So the rounded inlets sounds important. And hopefully the exhaust area is agreed upon at some stage, LOL. 39mm..... 38mm.....??

I have retracts... no ailerons, just elevons.... battery compartment made rearwards like Steve's (that was his?). Once again I totally forgot to check for threads on it!! So I re-invented the wheel(s)! I guess they always end up somewhat similar due to logic anyway....
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Old Apr 10, 2012, 07:45 PM
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Just a heads up Guys. If anyone needs a 5mm shaft adapter, I have some for trade.

http://www.rcgroups.com/forums/showthread.php?t=1630925

Mike
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Old Apr 10, 2012, 08:16 PM
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72% FSA exhaust shouldn't be a problem. As I recall from another thread right around 75% was the best compromise between speed/thrust/current draw. There have been several foamy F-15's that featured 64mm fans so fan size doesn't mean much.
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Old Apr 10, 2012, 09:10 PM
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Originally Posted by SteveC68 View Post
72% FSA exhaust shouldn't be a problem. As I recall from another thread right around 75% was the best compromise between speed/thrust/current draw. There have been several foamy F-15's that featured 64mm fans so fan size doesn't mean much.
ya it depends on a lot of factors but I agree generally, but I think the best comprimise is around 85% not 75% you can go down to the low 70's with slippery airframes (f16) and get some top end speed but with the more draggy airframes (f15) they like thrust and fly better that way. if this were my airframe I would start at 85%fsa and fly it and fine tune from their. if the vertical performance is good to great I would reduce the exit size and see how it goes. if the thrust is still marginal I would go bigger and would not be surprised at all if it flew best at 90%fsa (41mm each) each airframe and ducting are different so I adjust by how it flies
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Old Apr 10, 2012, 10:21 PM
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Originally Posted by jcdfrd View Post
ya it depends on a lot of factors but I agree generally, but I think the best comprimise is around 85% not 75% you can go down to the low 70's with slippery airframes (f16) and get some top end speed but with the more draggy airframes (f15) they like thrust and fly better that way. if this were my airframe I would start at 85%fsa and fly it and fine tune from their. if the vertical performance is good to great I would reduce the exit size and see how it goes. if the thrust is still marginal I would go bigger and would not be surprised at all if it flew best at 90%fsa (41mm each) each airframe and ducting are different so I adjust by how it flies
+1, I agree with jcfrd, I have always used 85% FSA for outlets. I like a fast model but this wont be a burner.

Eric B.
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Old Apr 10, 2012, 11:49 PM
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Done.

The unfortunate thing is that I was supremely rushed, getting out of work late, and fighting the unspoken evening noise curfew that us married EDFers are all too familiar with. The fortunate thing, however, was that I got some pretty definitive results that were somewhat surprising. Back in the negative part of the balance sheet, though, is that some of the most important results ended up being qualitative, not quantitative ... more on that later.

Also, my testing assumed something kinda important: with both fans operating at the same wattage on the bench - each with a lip and no thrust tube - the thrust of the CS10 is on par with its competition. Yes/No??

Anyway, with this assumption out there, here's the bottom line first:

It seems like the CS10 likes clean ducting, at least moreso than the DS30. It performed poorly in the EDO F-15, compared with the DS30.

Other observations:
  • The CS10 drew 50 more watts on the bench than when it was installed.
  • The DS30 drew slightly fewer watts on the bench than when it was installed.
  • The installed thrust of the CS10 was poor, nowhere near the installed thrust of the DS30. Note the assumption above - I didn't test the respective thrust values on the bench. Now in hindsight, should I have?
  • I need a thrust stand before I volunteer to do this kind of testing for the 'community' again. I.e more quantitative data.
  • One last observation, but not from this test: The CS10 in my F-35 (2:1:1 arrangement) definitely perferms on par with the E-Flite 70mm fan and the 8-blade nylon rotor from Efflux RC. So is the CS10 choking on the dual exhaust of the EDO F-15 afer all?
While y'all are chewing on this, I'll upload my video documentation that highlights some of the quantitative results I did capture. And then I'll go find a suitable place in my humble home where I can meditate on all y'all's criticisms of my testing methodology.

Don't worry, I already know it could have been better

Did I say I was uber rushed? Oh that's right, I did.



CS10 vs DS30 in the EDO F-15 RC Jet (10 min 44 sec)
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Last edited by Thomas Nelson; Apr 11, 2012 at 12:39 AM.
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Old Apr 11, 2012, 01:04 AM
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well thats a good example of why you cannot go by watts, you have to go by rpm of the fan rotor
you have two fans running at 450 watts and a 10k rpm diff. rpm is what matters watts are just the cost of doing business
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Old Apr 11, 2012, 01:16 AM
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DOH, that's what I need to do... measure the RPM in the F-15 also. To compare that to the benchtest.
I guess if the RPM are lower then the issue is back-pressure. But if the RPM are HIGHER it will be the inlet duct edges (lips) - because with no inlet lip the air feed is worse and thus less load on the fan.
.
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Old Apr 11, 2012, 01:27 AM
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Originally Posted by PeterVRC View Post
DOH, that's what I need to do... measure the RPM in the F-15 also. To compare that to the benchtest.
I guess if the RPM are lower then the issue is back-pressure. But if the RPM are HIGHER it will be the inlet duct edges (lips) - because with no inlet lip the air feed is worse and thus less load on the fan.
.
yes for a given setup, thrust is sort of an rpm measurment also more thrust means more rpm and less thrust is less rpm, the trick is to get the most rpm out of a given setup for the least cost of amps
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Old Apr 11, 2012, 01:29 AM
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Originally Posted by PeterVRC View Post
DOH, that's what I need to do... measure the RPM in the F-15 also. To compare that to the benchtest.
I guess if the RPM are lower then the issue is back-pressure. But if the RPM are HIGHER it will be the inlet duct edges (lips) - because with no inlet lip the air feed is worse and thus less load on the fan.
.
better yet fix both and go flying
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Old Apr 11, 2012, 04:51 AM
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I stand corrected, it is defenitly not starving with 150% FSA intake!

Based on my measurments on the CS shroud it is 69,8mm inner dia, and motor tube is 31,2.

85% FSA would be 40,7mm. 80% would be 39,5mm. Since its not a speed plane I would go with 85%.

I am using SMorrisRC FSA Calc
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Old Apr 11, 2012, 05:59 AM
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Originally Posted by foam and tape View Post
Anyone?
Here you go, here's the specs for that motor on 4S, looking at it, I don't think you'll be happy on 3S.

4S/15 volts, 60 amps, 778 watts, 1.47 k/ 3.234 pounds of thrust.
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Old Apr 11, 2012, 07:19 AM
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Oh and thanks for that informative, and entertaining, test video Thomas! LOL
Interesting that you have the rounded inlet edges... but probably the stock exhaust diameter? Maybe, if the CS10 runs more on the "volume" of air (can that be possible?) then the exhaust side would be more important than it is to the "high speed" air of the DS30....??

Anyway, a late start (10pm) but I am off to go and round my inlets... open out the exhausts... and re-test quickly....
Who knows... maybe this F-15 is just never going to be good for a CS10.
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