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Old Feb 19, 2013, 08:49 AM
wba
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Austria, Vienna
Joined Jan 2013
40 Posts
the pressure rises

ok my sabre is almost ready for maiden flight. excitement! the center of gravity is good. i decided to make two elevator servos. the programming of my dx6i ended up with an extra aileron on my elevator when i use the rudder stick. i used v-tail option and reversed rudder now both servos go up and down on elevator input and in opsite direction from each other on rudder input. flapperon is also programmed.

w.
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Old Feb 19, 2013, 09:59 AM
What Goes Up...Must Come Down
abjets's Avatar
United States, NC, Oak Island
Joined Jan 2013
875 Posts
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Originally Posted by wba View Post
how many mm max throw is necessary for the elevator to work well. i now got 3mm each way. is that enough? manual says 5mm :-(
WBA- I have found that the stock throws for the elevator are fine...the ailerons are very sensitive...i think that you should be OK or slightly on the light side for the elevator throws...I will measure mine tonight. I did back my ailerons way down and increased expo. She does love to roll!
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Old Feb 19, 2013, 10:20 AM
What Goes Up...Must Come Down
abjets's Avatar
United States, NC, Oak Island
Joined Jan 2013
875 Posts
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Originally Posted by wba View Post
ok my sabre is almost ready for maiden flight. excitement! the center of gravity is good. i decided to make two elevator servos. the programming of my dx6i ended up with an extra aileron on my elevator when i use the rudder stick. i used v-tail option and reversed rudder now both servos go up and down on elevator input and in opsite direction from each other on rudder input. flapperon is also programmed.

w.
Looking sweet! Are you running 3s??? I'm pretty sure that was your plan...I would highly recommend a thrust tube as it does make a world of difference. I used the Cone Layout software v2.0.5 (free for 21 days on the internet) and plugged in the outside diameter of the shroud (37mm) the desired length (I used 120mm) and with 85% FSA came up with an exit diameter of 30.312mm. (Set up all angles in the program to 0 degrees) Print this out with no scaling and trace onto some mylar or comparable. I used a Staples clear plastic filing folder. I attached the template to make it easier
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Old Feb 19, 2013, 07:41 PM
What Goes Up...Must Come Down
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United States, NC, Oak Island
Joined Jan 2013
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Originally Posted by wba View Post
how many mm max throw is necessary for the elevator to work well. i now got 3mm each way. is that enough? manual says 5mm :-(
WBA- I just measured my elevator throws and I am at 5mm...that is PLENTY when flying fast...you may want to get to 5mm for normal rates(slow flight might require it?) and see where you end up on dual rate. with the four servos and a bit more weight required for cg...you may need the throw??
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Old Feb 19, 2013, 09:26 PM
What Goes Up...Must Come Down
abjets's Avatar
United States, NC, Oak Island
Joined Jan 2013
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Originally Posted by wba View Post
how many mm max throw is necessary for the elevator to work well. i now got 3mm each way. is that enough? manual says 5mm :-(
WBA- to further this discussion...I have my Ailerons set at 4mm up throw and 3mm down throw. Elevators at 5mm up and down. Flaps at 2.5mm down with about 1.5mm of up Elevator mixed. Although I have not fine tuned the flap settings...it works pretty decent at altitude.
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Old Feb 20, 2013, 01:57 AM
wba
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Austria, Vienna
Joined Jan 2013
40 Posts
@abjets: thanks for the detailed information. i will adjust the throws and add some expo to the ailerons. i suppose too much aileron input is the cause of many launch troubles.

yesterday my esc (HobbyKing 10A ESC 1A UBEC) exploded on me so i am looking for a replacement. i am using the nano-tech 3s 350mah 65-130C battery. the TURNIGY Plush 10amp 9gram works well so far?

thrust tube? do you have a picture? i don't understand the concept.

w.
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Old Feb 20, 2013, 11:45 AM
What Goes Up...Must Come Down
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United States, NC, Oak Island
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@abjets:

thrust tube? do you have a picture? i don't understand the concept.

w.
WBA-Thrust tube simply allows the exit air to remain smooth and reduces the area from the rear of the fan to the exit by 85%...
If you notice the stock exit has an irregular shape and a lot of drag causing imperfections...the tube simply smooths all of this out so that there is minimal loss of thrust/efflux(speed). I simply slid the tube in the airframe, from the intake towards the rear(with the edf removed) installed the motor so that the tube just slides onto the edf shroud(small cut out for motor wires in tube and removed a small bit of foam from the aft portion of the fan seating area and hatch) and taped the tube in place being careful to keep the alignment of the edf and tube straight out the back. Once the motor was secure and glue dry...I secured the aft end of the tube with a small bit of foam...to minimize any wiggle.
The thrust tube makes a huge difference! There are some great threads in this forum on it for further explanation.

As for the ESC...I am using the Nano tech 3s 460 mHa 25-40C batts and the plush 10 amp with the shrink wrap removed and seated just in the airflow forward of the fan...absolutely no issues and barely gets warm.

Hope this helps! Cheers!
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Old Feb 21, 2013, 08:30 AM
wba
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Austria, Vienna
Joined Jan 2013
40 Posts
ah, ok, i see! thanks! maybe i will try that later. first i need to get her into the air. hopefully the new esc will be here soon.

how many minutes do you go on the 460 mah? not full throttle all the time but pushing it a little.

w.
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Old Feb 21, 2013, 10:08 AM
What Goes Up...Must Come Down
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United States, NC, Oak Island
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Originally Posted by wba View Post
ah, ok, i see! thanks! maybe i will try that later. first i need to get her into the air. hopefully the new esc will be here soon.

how many minutes do you go on the 460 mah? not full throttle all the time but pushing it a little.

w.
WBA- They are still new batteries with only about three flights on each (i have six) so I am setting the timer at 3 min and limiting WOT. All items remaining very cool and the batts show 73% fuel remaining...I will probably set the timer at 5 minutes, after a few more sorties on each. I think the Batts will outlast my eyeballs at staying focused on these tiny birds

The thrust tube makes a huge difference! If you have to solder in a new esc...might be a good time. You won't be disappointed!!! It will leap out of your hand for the launch Also: FYI not sure about your last ESC...but make sure you set your timing to low.
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Old Feb 21, 2013, 06:02 PM
Flying is Freedom
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Annandale, VA
Joined Jul 2007
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Originally Posted by abjets View Post
Looking sweet! Are you running 3s??? I'm pretty sure that was your plan...I would highly recommend a thrust tube as it does make a world of difference. I used the Cone Layout software v2.0.5 (free for 21 days on the internet) and plugged in the outside diameter of the shroud (37mm) the desired length (I used 120mm) and with 85% FSA came up with an exit diameter of 30.312mm. (Set up all angles in the program to 0 degrees) Print this out with no scaling and trace onto some mylar or comparable. I used a Staples clear plastic filing folder. I attached the template to make it easier
I don't know why but this PDF won't open for me
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Old Feb 21, 2013, 07:58 PM
always something to learn...
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Tacoma, WA
Joined Jan 2011
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Just picked up my second F-86 Saber today. I plan on 3s immediately, and will strip it apart to do some mods. I found that some of our welding wire for T.I.G. comes in clear plastic tubes that are exactly 35mm. I will be making a thrust tube out of one of those! My other one needs a new motor. ----Metalguy
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Old Feb 22, 2013, 04:28 AM
wba
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Austria, Vienna
Joined Jan 2013
40 Posts
@abjets: thanks for the many advices! i ordered two 460 mah batts along with the new esc. i love long flights. i also endet up using 2s 300 mah batts with my p51 um brushless converted.

@metalguy: way to go! consider the direct aileron servo mount. i have not testet em yet but they look very promising.

wba
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Old Feb 22, 2013, 01:11 PM
What Goes Up...Must Come Down
abjets's Avatar
United States, NC, Oak Island
Joined Jan 2013
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Originally Posted by Sky_Captain View Post
I don't know why but this PDF won't open for me
@ Sky Captain...Hmmm. I'll PM it to you too. The Thrust tube is actually 125mm in length ( I think I mentioned 120mm to WBA earlier. Still at 85% FSA for the 35mm EDF's). I have been using the STAPLES Document sleeves as material....not too heavy, yet they maintain their shape even after some abuse.
Cheers
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Old Feb 22, 2013, 03:31 PM
What Goes Up...Must Come Down
abjets's Avatar
United States, NC, Oak Island
Joined Jan 2013
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Originally Posted by metalguy View Post
Just picked up my second F-86 Saber today. I plan on 3s immediately, and will strip it apart to do some mods. I found that some of our welding wire for T.I.G. comes in clear plastic tubes that are exactly 35mm. I will be making a thrust tube out of one of those! My other one needs a new motor. ----Metalguy
MetalGuy,
The only problem with the 35mm tube is that you need a 37mm to fit around the outside of the exit of the Fan shroud...and to make it an actual thrust tube vs. just added weight with minimal benefits, it needs to have a taper to it. Ideally that taper should be 85% Fan Shroud Area (FSA) So the easiest is to make a template for a 37mm neck tapered to a 30.32mm exit and somewhere around 120-130mmm long depending on your preference. There is free software on the internet that you can load these figures into and it will then print you out a template...Cone Layout is the one I use for various EDF's. FYI- There is a 125mm long template(PDF) in my above thread for the F-86.
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Old Feb 22, 2013, 04:10 PM
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United States, FL, Sebring
Joined Feb 2006
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Folks, a moment of your time......

Actually, it's Fan Swept Area. The measurement will be different for each fan depending on the impeller's area, not just the total area of the shroud.

You guys might want to read up on the calculations. By not plugging the correct numbers into formulas, you are not getting the correct results..


http://hdflyer.com/how-to-calculate-...rea-of-an-edf/


Let's say you have a small fan of XX diameter and the 12mm inrunner that you are using sure seems to be about the same size diameter as the hub of the impeller. Figure the area of the circle using:

Area = Pi x Radiusē

That Area result gets subtracted from your total shroud area for your further calculations.



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Last edited by Joe 1320; Feb 23, 2013 at 09:38 AM.
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