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Old Apr 10, 2012, 06:34 AM
Extreme CNC Alloy EDF
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Australia
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Hey Eric,
70% in my calc shows 36.5mm, but do you think squeezing it down to 73% is going to bring the thrust down from 1.35 to 0.56kg?

Easy enough to slice the ends off the fuse until the diameters are at 39mm, and it will be very interesting to see if it picks up 800g in thrust!
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Old Apr 10, 2012, 06:59 AM
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The duct ahead of the exhaust nozzle gets a little big bigger in the first 40mm approx, but then opens up wider faster. I could cut them off something like 50mm or so ahead.... then add home-made thrust vectoring nozzles!!! Of appropriate size. But I can also test it with them just cut off first.
Or I can do it cleanly, so they can be put back on...... (or do both ways anyway!

I am a bit annoyed with this F-15 now!! So it is not too hard to decide to make it into a guinea pig, test plane!
Who knows, even if I hack it up a lot to work things out, I might be able to still complete it as a good model by the end. eg filler, glass, paint....
But what a project (time and effort), for a crappy little F-15!! LOL

I'll check it tomorrow evening and hack it down then!!

Thanks for the time doing the maths!! Though now we need everyone to come to a common figure! hehe
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Old Apr 10, 2012, 07:01 AM
EDF rules... :)
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Hi Mark, I used 37mm for the outlet diameter.
I do think that this is a lot of the problem.
The way to prove it is to make an outlet that coincides with the area of the models outlet and check it ont he thrust stand.
From my own testing going smaller than 85%-80% have exhibited this same thing, it takes a lot more hp to get the same flow to make the same force at smaller outlet area's.

Eric B.

PS, there will loss from the outlets having more wetted area than a single outlet so your right taking it up to 39-40mm per side should be ok and it will still be low but the overall velocity will still make flying it fun.
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Old Apr 10, 2012, 07:03 AM
EDF rules... :)
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Peter, careful cutting the oulet to get larger areas from it, if it gets too large then you will be at the other end of the stick where flight speed will not be satisfying. You might be able to get more from it by using a dowel and sandpaper to get the diameter to get 1mm at a time till your satisfied.

Eric B.
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Old Apr 10, 2012, 07:29 AM
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Good idea Eric!!
That is an easier first test.... which doesn't stop them being cut off some later time anyway.
Even once cut off, I am sure I can make up whatever is needed to complete them again. And as mentioned, thrust vectoring nozzles could be a fun way to do that too!
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Old Apr 10, 2012, 11:13 AM
3DHOG
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cool. looks like you guys beat me to it I am surprised to see that it is indeed choking the fan, I agree with Mark and airx, round the intake lip and open the exhaust to around 39.5mm each and you should see most of your thrust come back. that will put you around 85% fsa and will fly great
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Old Apr 10, 2012, 11:18 AM
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"Round the intake lip".... I assume you mean round off the sharp square edges of the very front of the inlet ducts? Inside curved to the outer edge (outside edge left square) of course.
I guess I will do the rear first... test... then do those fronts....
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Old Apr 10, 2012, 11:19 AM
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Hi Peter

Is this the 64mm EDO F-15, or a clone of one? I'm asking because I have one with a 70mm DS-30 fan and Mega 16-15-2 motor on 3S. From the few pics you've posted it looks the same? If so I'll offer that it's an Excellent performing jet on 450ish watts. Mine is setup to hand launch, and is extremely light. It has great T/W as evidenced here, and flies a treat as shown here.

All I did was open up the area where the fan sat, and smooth things immediately in front and behind the fan. I did nothing to the inlets other than some minor blending, and nothing to the outlets at all. No cheater in case you're wondering.

Could there be some other issue here maybe??

tn
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Old Apr 10, 2012, 11:27 AM
3DHOG
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Quote:
Originally Posted by PeterVRC View Post
"Round the intake lip".... I assume you mean round off the sharp square edges of the very front of the inlet ducts? Inside curved to the outer edge (outside edge left square) of course.
I guess I will do the rear first... test... then do those fronts....
yep thats what I mean you are losing a lot of thrust right their alone. have you bench tested a fan with and without the intake lip?.....same thing
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Old Apr 10, 2012, 12:03 PM
Retardedly intelligent
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Quote:
Originally Posted by foam and tape View Post
Hi all, I'm about to pull the trigger on a pair of these: http://www.hobbypartz.com/96m32-car-2848-2618.html The data looks pretty good on 4S but does anyone have any data on 3S, I want to use these fort the windrider 737 and my target weight for the plane is about 4-5 pounds. Would this motor be a suitable fit?
Anyone?
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Old Apr 10, 2012, 12:44 PM
3DHOG
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sorry cant help you there F&T but looks like it may work, I just dont like the fact thats its a car motor and thus has no cooling holes on the end caps of the motor, depending on the amp draw it still may be ok if amps are low. search this thread out there is a lot of testing on lower cell count setups, look for similar kv setup to give an idea what you might get
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Old Apr 10, 2012, 01:47 PM
I make bad look so good.
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Peter,

Check out this short thread on the EDO F-15. Like Thomas Nelson mentioned above the EDO and it's clones work fine with a 70mm fan.

http://www.rcgroups.com/forums/showthread.php?t=1595846
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Old Apr 10, 2012, 02:08 PM
3DHOG
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oh so its an EDO F15 64MM that explains why its choking a 70mm fan they would be way too big for a 64mm like its supposed to have, so anyway its probably better suited for a 70 anyway but some adjustments have to be made like we have already talked about, one thing different from the guys in the other thread they aren't using a 10 blade cs fan. running 70% fsa on a high rpm 6blader would be fine but not this low rpm 10blade setup....open the exhaust ducts and round the intake lips that will get you in the air and then you can fine tune it
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Old Apr 10, 2012, 02:11 PM
I make bad look so good.
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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.
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Old Apr 10, 2012, 02:33 PM
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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
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