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Old Nov 02, 2012, 03:15 PM
Team White Llama!
gundamnitpete's Avatar
Joined Jan 2008
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My big problem with the spear's aerodynamics was the abrupt change of the center section. Inbetween the two sides, the rear of the fuse area just dumps the air right before the fan. If that was filled in, and a splitter added that lead directly up to the fan, I think you'd eliminate alot of drag.

Also, on the rear end, the fuse doesn't taper back nicely. There's a nice big step before the end of the fuse and the EDF unit. If you fill that in, and taper it back softly, you'd pickup some speed aswell.

Are the spear's still available? I haven't flown an EDF in a while, and it would be fun to pick one up again. I'd probably only shoot for 120-130 though.
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Old Nov 02, 2012, 03:17 PM
High Dynamic Thrust
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United States, FL, Mt Dora
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fh64ucky is that CAT powered? :-))
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Old Nov 02, 2012, 03:18 PM
Ginger or MaryAnn ??
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United States, TX, Garland
Joined May 2005
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After looking at Steves, thats exactly what we are going to do and that should be the piece that puts us over the 200mph mark...I knew it needed to be done I just never got around to trying it.....
LOL Stone...you know it! =)
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Old Nov 02, 2012, 04:08 PM
Victim of C.D.O.
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United States, TX, Lubbock
Joined Oct 2007
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Two more spears coming??! JOY!!!
Can't wait!!

Joe'll be over 200. I'll be a little over that.
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Old Nov 02, 2012, 04:50 PM
Ginger or MaryAnn ??
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United States, TX, Garland
Joined May 2005
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LOL!!!!!! this will turn into full contact, I can see it now.....
Spears are a lucky find here and there...I seem to have decent luck getting them from private sales somehow.
Its not the takeoff or flights that hurt them,its the dang touch n go on landings that kill them with wing overs.
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Old Nov 02, 2012, 07:14 PM
Victim of C.D.O.
murdnunoc's Avatar
United States, TX, Lubbock
Joined Oct 2007
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Quote:
Originally Posted by gundamnitpete View Post
My big problem with the spear's aerodynamics was the abrupt change of the center section. Inbetween the two sides, the rear of the fuse area just dumps the air right before the fan. If that was filled in, and a splitter added that lead directly up to the fan, I think you'd eliminate alot of drag.

Also, on the rear end, the fuse doesn't taper back nicely. There's a nice big step before the end of the fuse and the EDF unit. If you fill that in, and taper it back softly, you'd pickup some speed aswell.

Are the spear's still available? I haven't flown an EDF in a while, and it would be fun to pick one up again. I'd probably only shoot for 120-130 though.
Is this what you're saying, Pete?
That chunk bothered me too, so I just went to town with some foam and a heated up pushrod. Still needs some cleanup but I think I'm on the right track.
I'll finish filling and smoothing around the intake at the sides, as there's a pretty good step there between the body glass and the fan mounting ring.
As a note, my Spear is actually a clone, so it may have a few details different from an Ultrafly Spear.
I've also cut up a slushie cup (small size from Sonic is perfect) to fair in the gap from the aft body to the thrust tube's end.
It'll be pretty "slickened" up when I'm done

The more airframe talk we get going in here, the better I see the Spear is for a high speed ship. (yep Joe, you told me...)
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Old Nov 03, 2012, 11:48 AM
Team White Llama!
gundamnitpete's Avatar
Joined Jan 2008
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To a certain extent, yes that's what I meant.

Try to draw to two sides together, so that they keep the left and right sides of the incoming air from mixing before hitting the fan. Basically, you want to keep the left side, and the right side separated until just before the fan.

Also, some extra rounding on the outside intake lips never hurts. As round and as smooth as possible.

The sharp edges of fighters make people think that sharp=fast, but that's not really true when we are talking sub sonic. Subsonic likes smooth and round. So get that bird and smooth as you can! I'm talking tape over seams, servo covers, the whole nine yards. The small details count at these speeds!
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Old Nov 03, 2012, 11:56 AM
Team White Llama!
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Joined Jan 2008
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Basically, run your finger across the side of the fuse, heading toward the fan. Notice right as the intake stops, there's that sharp lip? Run your finger across it, it's hard and jagged. When the air hits there, it's gonna breakup right there before the fan. And since that's on both sides, you're gonna have some nasty mixing going on there.

That's the area I would extend back, and taylor it right into the fan, keeping both sides separate until the fan. That should help out ALOT.
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Old Nov 03, 2012, 03:23 PM
High Dynamic Thrust
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United States, FL, Mt Dora
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that middle divider should be super smooth, going as close to the rotor as you can get it.
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Old Nov 03, 2012, 08:25 PM
Victim of C.D.O.
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United States, TX, Lubbock
Joined Oct 2007
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Grrr... That's going to interfere with my plans to do a bunch of rotor and motor swapping
I'm able to get to the rotor and pull it out through the front, and then release the motor out the rear as it is right now. Won't be able to remove the rotor with the divider going all the way up to the fan. I hate to dismount the whole fan when I want to make a change. And I fiddle a lot with swapping out components.

Guess you can't have everything.

...unless I make the divider removable with a couple of pins... Will work on that!

I'll for sure at least get the transition super smooth with microballoons and sanding.
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Old Nov 26, 2012, 01:37 PM
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Joined Nov 2012
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200mph in a tiny jet like that .dont forget your carrier bag 4 the bits....thats if you can find them
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Old Nov 26, 2012, 02:05 PM
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United States, CA, Santa Clarita
Joined Aug 2009
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Quote:
Originally Posted by boxster View Post
200mph in a tiny jet like that .dont forget your carrier bag 4 the bits....thats if you can find them
This one did 152 before a 2.4 gHz lockout (early AR6100) turned it into the "bits" .

The next one built, did 173.
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Old Nov 26, 2012, 02:32 PM
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dallas tx
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Gary, thats fixable!!!
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Old Nov 26, 2012, 04:11 PM
Victim of C.D.O.
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United States, TX, Lubbock
Joined Oct 2007
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Quote:
Originally Posted by boxster View Post
200mph in a tiny jet like that .dont forget your carrier bag 4 the bits....thats if you can find them
Jet like what?
Spear?

This is no foamie pulled from the box with 4kW strapped to it.
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Old Nov 26, 2012, 05:34 PM
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Originally Posted by capt soap View Post
Gary, thats fixable!!!
Cory will tell ya, I'll repair almost anything. But not that black one. This one (my first) was repaired 6 times. Either pilot error, (me) or lockouts. It was saved a cuople of times from reboots. with that early rx. I finally went to the AR6200 and never a problem since at our field that's know for having a "devils triangle" area for 2.4 noise. (nearly 5 years ago)
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