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Old Dec 04, 2012, 10:02 PM
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looks fast Lee.
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Old Dec 04, 2012, 10:07 PM
Lee Liddle
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Carrollton, Tx
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Originally Posted by LuvEvolution7 View Post
looks fast Lee.
It will be. The prototype was capable of doing 90mph. I think this one will break 100mph. So just multiply everything by 2, and you get a 70mm edf that will break 200, right?
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Old Dec 04, 2012, 10:24 PM
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Originally Posted by murdnunoc View Post
So the 90mm CS rotor cut down to 70 would blow up at 60K?
Has anyone tried? Isn't that what Knife Liddle has on his super fan??
Ive cut down a CS 90mm to fit a 70mm fan, ran it at 60K and it was fine. The thrust wasnt there though even on 8cells. I havent tried it at a higher RPM.
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Old Dec 04, 2012, 10:50 PM
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Them's some good math there, Lee.

Double the diameter, double wingspan and battery, and you should double the speed.

FOOLPROOF!!

...that thing looks a little Spear-ish
Nice airfoil?
That's something that's haunting me about the Spear. It's pretty flat-bottomed which is not what we need for straight line speed.
Though it may prove a little beneficial for pulling out of the dives, giving up a little less induced drag for the huge lift that's created by the high G pullout.
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Old Dec 04, 2012, 10:53 PM
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Originally Posted by johnny_0 View Post
Ive cut down a CS 90mm to fit a 70mm fan, ran it at 60K and it was fine. The thrust wasnt there though even on 8cells. I havent tried it at a higher RPM.
Was that static test??
Open pipe or thrust tube?

I'd expect that with the cut down blades and associated high pitch, static thrust would be low but efflux would be through the roof.

Any data points on watts/rpm you can share?
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Old Dec 05, 2012, 12:13 AM
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Originally Posted by Knife Liddle View Post
It will be. The prototype was capable of doing 90mph. I think this one will break 100mph. So just multiply everything by 2, and you get a 70mm edf that will break 200, right?
if only it were that easy, eh!? LOL.
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Old Dec 05, 2012, 12:59 AM
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Originally Posted by murdnunoc View Post
Was that static test??
Open pipe or thrust tube?

I'd expect that with the cut down blades and associated high pitch, static thrust would be low but efflux would be through the roof.

Any data points on watts/rpm you can share?
Sorry I wish I had the numbers for you but Im very basic with my testing.
I mounted the fan in my 70mm HK viperjet, using the Eflite delta 32 motor. Did the static test and it wasnt lifting its own weight , maybe 0.7:1 weight ratio that was enough for me. If I dont have at least 1:1 thrust in any of my EDF jets. Im not flying it
I dont think Im emotionally equipped to shave down a 90mm wemo a 90mm or shubie fan to fit a 70mm housing
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Old Dec 05, 2012, 04:22 AM
Lee Liddle
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Carrollton, Tx
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Originally Posted by murdnunoc View Post
Them's some good math there, Lee.

Double the diameter, double wingspan and battery, and you should double the speed.

FOOLPROOF!!

...that thing looks a little Spear-ish
Nice airfoil?
That's something that's haunting me about the Spear. It's pretty flat-bottomed which is not what we need for straight line speed.
Though it may prove a little beneficial for pulling out of the dives, giving up a little less induced drag for the huge lift that's created by the high G pullout.
At only 4oz auw it doesn't need much airfoil, just a little shaping here and there. I agree on the Spear. It looks to me like the Spear is fast in spite of it's airfoil, not because of it.
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Old Dec 05, 2012, 04:33 AM
Lee Liddle
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Carrollton, Tx
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Originally Posted by Knife Liddle View Post
It will be. The prototype was capable of doing 90mph. I think this one will break 100mph. So just multiply everything by 2, and you get a 70mm edf that will break 200, right?

Oh, I forgot to mention....the 70mm version will have 20 x the Watts, No, seriously, get your ready boys.
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Old Dec 05, 2012, 11:29 AM
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Originally Posted by murdnunoc View Post
Why do I get the feeling I'm not the only one who's walked around the grocery store with a caliper in my back pocket, closely eyeing all the drink bottles and cleaning products?
My Habu32 is flying on a Fosters beer can sized shroud I'm probably lazy, but it seemed like a better idea than spending all day making a round plug, plus these have a treat inside

The Spear root airfoil is probably ok, but it needs a bit more twist or a change in airfoils at the tip because mine needs the elevons up all the time and that's draggy. These high lift airfoils look wrong for a speed plane, but if it ends up weighing a bunch like mine does, then the airfoil is always flying at a small positive angle of attack and this airfoil could be low drag in that range.

I can probably come up with a 70mm fan, but I'll have to make a new plane for it. If I can't find something around here, I might take you up on that filter housing though!

Your little plane looks cool Lee. Will the big one have the motor in front of the fan like you were planning before?
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Old Dec 05, 2012, 12:19 PM
Ginger or MaryAnn ??
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United States, TX, Garland
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The Spear handles well at 190mph,I think the airfoil that it has is will do just fine....
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Old Dec 05, 2012, 12:22 PM
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Steve, do you bond the aluminum can to the composite weave, making it a permanent part of the shroud? Or is it removed once the epoxy has cured?
I have visions of laying up the full Fosters can, and then enjoying the carbon-fiber wrapped brew before cutting it to size
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Old Dec 05, 2012, 12:30 PM
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Originally Posted by fh64_lucky View Post
The Spear handles well at 190mph,I think the airfoil that it has is will do just fine....
Handling well, absolutely. The thick, lifting airfoil and significant washout will have a positive impact on its low speed handling. But all that lift gets in the way at high speeds, creating drag that will have to be overcome with more power.

More power. Aww, shucks!

It's not a deal breaker by any means. I know there are compromises with any production airframe.
Just making my list if I ever decide to get really crazy on an airframe...
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Old Dec 05, 2012, 12:33 PM
Lee Liddle
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Carrollton, Tx
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Originally Posted by Steve C View Post

Your little plane looks cool Lee. Will the big one have the motor in front of the fan like you were planning before?
Maybe, may try it both ways.
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Old Dec 05, 2012, 01:23 PM
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The only time I've seen a flying wing win in a speed event is when the challenge was limited to flying wings.
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