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Old Jul 20, 2011, 10:25 PM
Team30 Micro EDF
NitroCharged's Avatar
Adelaide, Australia
Joined Apr 2004
11,254 Posts
Size the front and the back of the pipe up and tape it all up. Then flatten the tube and bend it to form a U shape. Stick it up the tail. Let it pop back open. Wiggle the front of the pipe onto the housing and use 2 dabs of hot glue or tape to hold it in place. I put a surround of 2mm depron into the tail to hold the end in place. I applied 2 drops of CA to keep it all there.
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Old Jul 20, 2011, 10:32 PM
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ducatirdr's Avatar
United States, MA, Sutton
Joined Aug 2006
1,489 Posts
I finished my Mig tonight. The AR6300 incompatibility with the HKM2824 servo connectors had me stalled till I purchased some 3 inch servo extensions for the AR6300. The part number is SPMEXJST3UL. I modified the female end by breaking the connector carefully to release the pins. I then plugged the pins into the male end on the servo connectors Futaba style mini JST. A little blenderm to hold them together and I had connectivity to my servo's. My ARF came without the control arms and push rods for the ailerons so I salvaged some from my old Mini 4 Site.

I balanced out using the Rino 360 3 cell and used a Turnigy 6 amp ESC. It's what I had.

I short toss under the lights at the local sports field showed my wings are really warped bad. They came out of the box twisted. I tried to press them flat for a few days under some carefully placed batteries but the twist is still there. Anyone have any ideas how to straighten EPO foam wings? The hair dryer was a bad idea

Tom
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Old Jul 20, 2011, 11:33 PM
Thatsright I drankthe rum
K9000wner's Avatar
USA, MN, Robbinsdale
Joined May 2006
1,343 Posts
Quote:
Originally Posted by Odysis View Post
NC made his tube, and didn't mod the airframe.
For me, it was a quick, 2 min job to shrink the tail down a bit, whereas splitting the fuse takes a while. I've only tried to fit a thrust tube after fan installation once. Never again! So fiddly, as Slaanesh said, not worth it in my book.

34mm still seems excessive for a 35mm fan. But then again, NC may not be using the stock fan...
go back to post #549 (page 19)and look what options you have....

http://www.rcgroups.com/forums/showp...&postcount=549

maybe I can get the link to work
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Old Jul 20, 2011, 11:53 PM
ancora imparo
jj604's Avatar
Melbourne, Australia
Joined Jul 2005
6,868 Posts
Thanks. I had forgotten that useful post.

Nitro, Ody, Slaan, [insert expert name here], what would your recommendation be for the stock motor and fan on 2S and 3S for the percentage?

Thanks again.
Quote:
Originally Posted by K9000wner View Post
go back to post #549 (page 19)and look what options you have....

http://www.rcgroups.com/forums/showp...&postcount=549

maybe I can get the link to work
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Old Jul 21, 2011, 01:28 AM
Not enough hours in the day
Slaanesh's Avatar
Melbourne
Joined Feb 2009
2,429 Posts
A good thrust tube should be smooth and clear of obstructions.
It's purpose is to keep your preciously generated airflow smooth and clean - the restriction of the exhaust diameter serves to increase the efflux speed.

Theory:

mass flow rate = r * V * A

where:

r = density (air)
V = velocity
A = flow area

With a thrust tube you are reducing A, therefore V will increase as r remains constant. You are exchanging thrust for speed.

A good rule of thumb is 80% however you really want "disposable" thrust - ie a relatively powerful setup to trade a bit of thrust for efflux speed.

For a 2S setup I would go highter than 80% - probably more like 85-90%
For a 3S setup I would go the 80%

In a 35mm EDF we are only talking 2mm difference. 80% FSA is 28mm. 90% FSA is 30mm.

As I am still on 2S, I'm going to try 90% on mine tonight and hopefully give it a "test drive" tomorrow morning - weather permitting. The wind hasn't been kind in "sunny" melbourne for the past few mornings.
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Old Jul 21, 2011, 01:42 AM
Team30 Micro EDF
NitroCharged's Avatar
Adelaide, Australia
Joined Apr 2004
11,254 Posts
85% FSA is 27mm...

(rotor diameter)˛ - (hub diameter or motor diameter :- whichever is larger)˛ = FSA (Fan Swept Area)

√FSA x 0.85 = 85% FSA exit diameter.

e.g.

With the rotor diameter of 35mm and motor bell of 14mm diameter:
35mm˛ - 14mm˛ = 1029mm

√1029mm x .85 = 27.2mm diameter

.
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Old Jul 21, 2011, 02:39 AM
Not enough hours in the day
Slaanesh's Avatar
Melbourne
Joined Feb 2009
2,429 Posts
I was using the values from here:

http://www.rcgroups.com/forums/showp...&postcount=549

This spreadsheet uses a motor with a 15mm diameter - thus the differences between the figures I've given and NCs.

So... is the motor 14mm or 15mm?
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Old Jul 21, 2011, 03:33 AM
Team30 Micro EDF
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Adelaide, Australia
Joined Apr 2004
11,254 Posts
14mm according to my callipers.
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Old Jul 21, 2011, 03:53 AM
Team30 Micro EDF
MegaTesla's Avatar
Stellenbosch, South Africa
Joined Apr 2004
2,060 Posts
Shouldn't you guys use the motor tube outer diameter? The motor bell is larger, but it is sitting further back in the air stream, and not directly behind the rotor.
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Old Jul 21, 2011, 06:02 AM
Team30 Micro EDF
NitroCharged's Avatar
Adelaide, Australia
Joined Apr 2004
11,254 Posts
Which ever is largest: rotor hub, motor mount, outrunner bell.
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Old Jul 21, 2011, 07:32 AM
It's a spiderweb of knit lines
Souderton Pa. USA
Joined Mar 2002
2,651 Posts
Based on wing warps I've seen on some Migs I'd have to guess that some will have up thrust and some won't.

If you have excessive up thrust, moving the CG back will add to the problem.

In my experience thrust line is one of the hardest things to get right on a scratch built micro edf.
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Old Jul 21, 2011, 10:46 AM
Registered User
dude_109's Avatar
Houston, TX
Joined Jan 2008
5,779 Posts
Quote:
Originally Posted by ducatirdr View Post
...I short toss under the lights at the local sports field showed my wings are really warped bad. They came out of the box twisted. I tried to press them flat for a few days under some carefully placed batteries but the twist is still there. Anyone have any ideas how to straighten EPO foam wings? The hair dryer was a bad idea

Tom
Use hot water. Not too hot, else you'll get the alligator skin. I use a coffee maker to brew the water which someone said should have been around 190* F. Slowly pour it on the foam while bending the part. Keep holding the part for a couple of minute while it cools into the new shape. Repeat as necessary until it gets to where you want it.

Many of these planes come out of the box bent from being taped too hard to the box so I end up needing to do this practically for every plane.
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Old Jul 21, 2011, 10:49 AM
Richard Cox
Thousand Oaks, CA
Joined Dec 2003
672 Posts
My first F-86 is still in the tree. Replacement arrived yesterday.
Removed a little foam to shoehorn in the 460 nanotech battery, and the CG came out
exactly where the original with the 360 battery and 1/4 oz nose weight was.
To use the AR6300, swap the red and brown wires on the servo plugs by carefully
prying up the plastic fingers on the connector while gently pulling on the wire,
then reinsert the brown wire in the middle and the red wire on the end.
Trim off the little bump of plastic on the connector housing and press them into the
AR6300. They are tight, but they fit. I cut a little trough on the right side of the fuse
so the RX fits down flush with the top of the canopy opening, with the connectors
toward the front. Couple drops of hot glue keep it away from the elevator servo arm.
Very clean, and allows room for the battery after trimming the foam bulkhead ahead of
the servo.
Maiden today.
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Old Jul 21, 2011, 01:03 PM
Registered User
United States, CA, San Diego
Joined May 2004
473 Posts
Quote:
Originally Posted by Odysis View Post
Guppy - I left the pins on my Rx, but took the plastic keepers off the micro servo leads. The metal sockets will still fit onto the standard sized pins. I was thinking of removing the pins and soldering everything, but when I found they fit with very minimal modification, I couldn't help but be lazy!
Great thanks for the tip. I'll pick up a receiver today and give it a shot. Still waiting for my batteries to arrive from China before my first flight.

scott.
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Old Jul 21, 2011, 01:41 PM
Registered User
Halifax, NS
Joined Sep 2009
404 Posts
Quote:
Originally Posted by Odysis View Post
Guppy - I left the pins on my Rx, but took the plastic keepers off the micro servo leads. The metal sockets will still fit onto the standard sized pins. I was thinking of removing the pins and soldering everything, but when I found they fit with very minimal modification, I couldn't help but be lazy!
Hmm, never thought that the sockets in the Molex Picoblade connectors would fit standard servo pins. I was going to cut off the micro servo connectors and crimp on standard female connectors to use with a 4ch OrangeRx. Now I may not have to.
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