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Old Dec 28, 2010, 11:43 PM
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United States, TX, San Antonio
Joined Mar 2010
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Hey guys, I was looking a some pkz extra 300 threads when I stumbled across this one. I now really want to make one of these flying wings(like the ones talked about on the first page), but no one talks about how much it costs to make one. About how much is does the foam, motor, esc, and batt. cost to build this basic wing design? Thanks for the help, I hope it is cheap!
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Old Dec 29, 2010, 02:39 AM
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USA, WA, Bremerton
Joined Feb 2007
851 Posts
cheap foam wings

Figure you go with Dollar Store type foam board (2-3 bucks there). Some hot glue. Two $6.00 servos. A cheapo ESC BL combo ($22 or so - check out ( http://www.headsuprc.com ) and $10 for a basic 1000 mah 3s pack. It can be very low cost compared to buying planes at your LHS.
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Old Dec 29, 2010, 11:51 PM
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United States, TX, San Antonio
Joined Mar 2010
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Thanks. Well I built one. I have not flown it yet, that is for tomorrow. I am using a the exact build designs mentioned in this thread. I am using a 30amp ESC, 420 brushless outrunner motor 3800kv eflight ducted fan motor, and a 11.1v 1300mah lipo. As you can see in the pictures I have positioned everything according to what people recommended. From the pictures, would you guys change anything before my maiden tomorrow?
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Old Dec 29, 2010, 11:52 PM
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How do you post pics? I cant seem to post the ones of my new wing.
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Old Dec 30, 2010, 03:57 AM
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doggit's Avatar
northenden, manchester, england
Joined May 2009
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you need to click on new reply then scroll down to manage attachments, then click on that button, a new box will appear with browse buttons on, click on one and go to where your pics are on your computer add the picture then go to next button and add another, when pics have uploaded you will see them in that new window, add comments if you want under the pics, then click save changes, and hey presto your pics will be in your post
carl
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Old Dec 30, 2010, 06:45 AM
Will work for foam
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United States, WI, Muskego
Joined Apr 2005
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sawman - no, there aren't any bugs in the sheet for making big wings. i am thinking you might have over written a formula or two. did you only change the values in the blue fields? those that are not blue should have a formula in them. i PM'ed my email to you to send a copy of the sheet you used to build your last wing so i can review for any problems.

Suggested speeds - the stall speed is simply that calculated by taking the square root of the wingloading and multiplying by 4. this is quite accurate and was verified by my latest wing using an onboard airspeed indicator. the Average Speed is somewhat ambiguous, but is based off of MotoCalc's use of full speed being 3x the stall speed. the average speed is calculated to be 1.95x stall speed and is also used to generate the Reynolds numbers of the root and tip airfoils. put more weight on the stall speed if anything.

wingnutt
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Old Dec 30, 2010, 09:45 AM
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Louisiana
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Ok Wingnutt,
I did not get your PM but sent you one with my email address. Hopefully it makes it through.
I did enter information as instructed on the spreadsheet (only blue fields). I think I'm making my cuts wrong, but don't know why ??? On the Gentle Giant I believe it had something to do with the "sweep" value that I didn't monitor closely. Crazy because it looks and flies great !
I'm really digging this thinner profile wing. Should be nice and slippery in the air!
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Old Dec 30, 2010, 10:11 AM
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United States, TX, San Antonio
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Quote:
Originally Posted by fishon2 View Post
Thanks. Well I built one. I have not flown it yet, that is for tomorrow. I am using a the exact build designs mentioned in this thread. I am using a 30amp ESC, 420 brushless outrunner motor 3800kv eflight ducted fan motor, and a 11.1v 1300mah lipo. As you can see in the pictures I have positioned everything according to what people recommended. From the pictures, would you guys change anything before my maiden tomorrow?
Here should be the pics, any suggestion before I throw this baby in the air?
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Old Dec 30, 2010, 10:43 AM
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sawman's Avatar
Louisiana
Joined Oct 2005
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Quote:
Originally Posted by fishon2 View Post
Here should be the pics, any suggestion before I throw this baby in the air?
Prop is too close to wing. In my experience this causes cavitation because the airflow in front of the prop is blocked. Thrust will be reduced too much and lots of noise. I read somewhere that it was suggested to keep at least 3 inches of separation.
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Old Jan 01, 2011, 12:05 PM
Will work for foam
wingnutt's Avatar
United States, WI, Muskego
Joined Apr 2005
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sawman - after playing in autocad, i see that the dimensions you input would yield a 57.05" span wing. i think where you should have cut the bottom offset to 7.25", you cut to 2.548" (the tip top offset). This will give the 70.5" span plane you ended up with. should just be able to cut another <4.75" to get the 57" span you desired.
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Old Jan 01, 2011, 12:35 PM
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Austin TEXAS area
Joined Apr 2008
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Fishon check that prop it looks like it might be on backwards--hard to tell from a picture but it kind of jumped out at me--I could be wrong-ask my wife shes says it happens all the time! Good luck with your maiden. By the way I just maidened my first bluwing this weekend--built to the original size spec's and it flies great. pops out
Quote:
Originally Posted by fishon2 View Post
Here should be the pics, any suggestion before I throw this baby in the air?
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Old Jan 01, 2011, 04:36 PM
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Louisiana
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Originally Posted by wingnutt View Post
sawman - after playing in autocad, i see that the dimensions you input would yield a 57.05" span wing. i think where you should have cut the bottom offset to 7.25", you cut to 2.548" (the tip top offset). This will give the 70.5" span plane you ended up with. should just be able to cut another <4.75" to get the 57" span you desired.
LOL ! Thanks Wingnutt. If there is a way to mess up, I WILL find it ! I just have a knack for doing this. Lots of skill, really. Not everyone can pull it off !
I plan to trim a little off each tip....just enough to fit the cab of the truck. Next week, I'll start the equipment layout.
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Old Jan 01, 2011, 07:05 PM
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United States, TX, San Antonio
Joined Mar 2010
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Well I maidened and my home made wing flew without any trouble. My elevons need more throw. Should I make the servo arms longer and put the push rod in a whole closer to the wing? Also, I used a eflite 420 3800kv motor with a eflite 30amp brushless ESC and a 1300mah 3c battery and when I got just over half throttle the motor would stutter and then die. Then I would bring the throttle back down to zero and then give it more and it would be fine. Any thoughts on what this issue is? Thanks for all your guys help, my first wing and I had no major issues!
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Old Jan 01, 2011, 08:22 PM
IFO's are planes too
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Petersburg, Va.
Joined Dec 2008
432 Posts
HI fishon2,
Sounds to me like your pushing the current limits on your system with
that high KV motor. I looked up the specs and the burst current rating for
the 420 motor is 32amps for 15 sec, so that's your max draw.
Try using a smaller prop and check the system with an amp meter.
You could go with a 40 ESC or a lower KV motor to be safe, but you still
have to obey that 32amp current limit or the motor is toast.
They a tendency to take the ESC with them when they go up in smoke.

Servo throw: I use CF rods (1.7mm) CA'd to a dubro mini kwik-link (#228)
They are go for up to 12" long, but anything longer and you'll need a sleeve
midway to limit any bowing.
Hope this helps you and I bet that 3800 kv motor really rocks on anything
it's used on.
Al.
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Old Jan 01, 2011, 09:45 PM
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United States, TX, San Antonio
Joined Mar 2010
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Quote:
Originally Posted by atone1 View Post
HI fishon2,
Sounds to me like your pushing the current limits on your system with
that high KV motor. I looked up the specs and the burst current rating for
the 420 motor is 32amps for 15 sec, so that's your max draw.
Try using a smaller prop and check the system with an amp meter.
You could go with a 40 ESC or a lower KV motor to be safe, but you still
have to obey that 32amp current limit or the motor is toast.
They a tendency to take the ESC with them when they go up in smoke.

Servo throw: I use CF rods (1.7mm) CA'd to a dubro mini kwik-link (#228)
They are go for up to 12" long, but anything longer and you'll need a sleeve
midway to limit any bowing.
Hope this helps you and I bet that 3800 kv motor really rocks on anything
it's used on.
Al.
Ok, so basically I am maxing out my motor? I think my whole problem with this delta wing build is that when I went to my LHS I wanted a rear mounting motor to give my prop clearance like ALL the other wings I have seen, but the owner convinced me to get this motor. So what should I do? Should I try and return it and get a motor that is meant for the setup im running? Im using an APC 7x5 prop attached 1/4in from the back of the plane due to the mounting issues I discussed earlier.
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