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Old Feb 24, 2009, 05:53 PM
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Quote:
Originally Posted by j4ck4
Oh, by the way great looking wing!! Are the graphics tape?
Believe it or not, it's all done with Sharpy markers and some patience...
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Old Feb 24, 2009, 09:42 PM
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Quote:
Originally Posted by j4ck4
You can use this calculator to set your cg http://www.willhaney.com/zagnutz/
Mine usually are in the range of 7 - 81/2". Just shift your battery around, I have been flying these with both a gws 350b gear and a 400a gear and they do fly great. I'm actually using a 7.4v nimh pack out of a Hobbyzone Supercub. So, your Stryker electronics if I understand anything about Strykers should make it a rocket.
Have fun these are great wings, and if you want a little spice check out the Kline Fogleman build thread lots of great ideas over there.
http://www.rcgroups.com/forums/showthread.php?t=558321 Wings rule!!
The zagnuts calculator was kinda fixed to the shape and sweep of the zagnuts.

I found these 2 calculators that lets you enter all the numbers for the dimensions to accurately calculate a CG for this wing shape.

http://www.palosrc.com/instructors/cg.htm

and

http://fwcg.3dzone.dk/

I like the 2nd site better because it helps you decide what %MAC you should use.

At 20% MAC, it comes out to 7" (all around flying skills).
At 25% MAC, it comes out to 7.5" (for expert flyers).

I'll start with 7" and work from there...

Thanks for your reply...
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Old Feb 25, 2009, 09:02 AM
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United States, OK, Tulsa
Joined Dec 2008
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Yeah I had one of those actually, the fwcg.3zone. They are good I have a couple others that I have found also i think. Just mainly use the one I had posted, but the more options we have the better, check balance severalo ways that way.
Ur welcome.

Jack
Help save planet Earth, it's the only planet with chocolate!
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Old Feb 25, 2009, 09:56 AM
Will work for foam
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United States, WI, Muskego
Joined Apr 2005
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After watching this thread since the beginning, i finally took the plunge and built me one of these wings. My orignial plan was for a light build to yeild a quick and solid flying wing mostly for thermaling (thermals are pretty strong here). But now that the windy season is upon us, i went for a heavier/robust built ship that could penetrate yet still thermal reasonably well. I went with a 1320 3 cell battery, a custom wound 2408-17 motor and a Maxx 5x5 carbon prop. AUW was a heafty 10.95oz.

The plane is mostly per the original plans except for 2 small changes. First, i used an S5020 airfoil at the root (root rib was cut compensating for FFF thickness), but left the tip airfoil as symmetrical as possible. Second, i made the elevons slightly thinner (1.25" near prop and 2" at the tips). Only other difference is in the CG. Original plans state to start with 7" and work your way back. After building i took some measurements and washed them through my wing design spreadsheet and it suggested a CG of 8.25" back for a stability factor of 5%. I set the CG at 8" and headed out for the maiden.

WOW! What a great flying wing! I am truely impressed. Although still noseheavy at 8" back, it flew great. The wind was blowing 15mph+ but it didnt care. Not a hint of tip-stall and all control response was rock solid. After a quick trip to thermal altitude (just gotta love unlimited vertical) i cut the power and was very impressed by the glide. It seemed to float forever - much better than i expected at a wing loading of 5.5oz/sqft and an aspect ratio of 3.6. I am very happy with this plane and cannot wait for some decent thermaling weather to move the CG back some more and really test it out.
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Old Feb 25, 2009, 10:05 AM
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United States, OK, Tulsa
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Quote:
Originally Posted by cjbucher
Believe it or not, it's all done with Sharpy markers and some patience...
Thats cool, I just bought two big packages of the giant sharpie chisel tip markers. Maybe I can do as good a job on my next wing.
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Old Feb 25, 2009, 12:48 PM
Will work for foam
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United States, WI, Muskego
Joined Apr 2005
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ok, i moved the cg back some more to 8.25" and it really comes to life. more nimble on the sticks, but will drop a wing if you get too ham fisted at low speeds. not an issue really as it recovers almost immediately when the stick are released. it just keeps getting better! thanks again for the design.
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Old Feb 26, 2009, 07:11 AM
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Hi Guys,

Im a complete noob at building wings this would be my first and have a few questions:

Which is better 3mm or 5mm EPP foam?
What is a 15 turn cd motor? What motor can you recommend?


Thanks,
Mathew
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Old Feb 26, 2009, 08:05 AM
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Quote:
Originally Posted by erozion
Which is better 3mm or 5mm EPP foam?
I would say use 5mm EPP if you are going to try and make one of these out of EPP. Most people used bluecore which is more rigid so if you go with EPP you may end up with a floppier wing or else you'll need to use more carbon fibre (or whatever material you choose) to brace the wing and stop it bending under load. I suspect 3mm EPP would be far too floppy and weak to make a good wing.

I used 5mm EPP and reduced dimensions slightly to produce a smaller wing with good results. I ran a length of 4mm diameter carbon fibre tubing up each of the bits of foam used to shape the airfoil and another peice to run between them creating an A shaped frame of carbon fibre. This resulted in a wing both stiff and strong and weighing just under 9 oz all up (although only 24" wingspan).



Just bear in mind that whilst you will likely end up with a bouncier more resillient aircraft using EPP than bluecore you'll have to go to more effort to reinforce it to keep it stiff and be very careful not to build it too heavy as a result.
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Old Feb 26, 2009, 08:09 AM
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Thanks teslahed,

The only thing staying here in South Africa, i cant find bluecor only EPP. Gonna have to try it out and reinforce in an A shape like you say.
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Old Mar 09, 2009, 09:54 AM
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Raleigh, NC
Joined Sep 2004
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42" Wing - Maiden went well!

Finally got all the electronics installed and got 2 flights in this morning. This is a nice flying wing. Smooth and floaty. Easy to launch and easy to land. Also has a good speed range. Fly slow or up to about 60 mph or so.

I moved my Park 400 4200 kv from my small wing to this wing. I did use a GWS gearbox with a 2.8 to 1 gear ratio and a 7x5 prop. The plane weighs 17 oz but generates 28 oz of thrust!

Part of the reason I moved the power system was that I was using a 4.1x4.1 prop on that high kv motor. While I did get 80 mph out it, it was really sucking down the power. Only 6 minute flights on an 1800 mah battery. I was running that motor way too inefficiently... But geared 2.8 to 1 with a 7x5 prop and now I'm getting over 10 minutes easily (probably more). After 8 minutes I still had 11.45 volts on the pack... Dramatic improvement in power consumption and efficiency.

Probably my only gripe is that I had to cut in quite a bit for the motor in order to get everything to balance. The battery is about as forward as I can get it...
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Old Mar 11, 2009, 12:30 AM
we spozed ta be tite!
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Nowata, OK
Joined Aug 2005
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My twist one this fine little wing.

My Down and Dirty Maiden Report.
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Old Mar 11, 2009, 09:36 AM
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Quote:
Originally Posted by fr0g_D
Sorry to hear about your crash. But the good thing is that these wings are easy to build. You'll have another one ready in a couple of hours...

What kind of receiver were you using?
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Old Mar 11, 2009, 09:49 AM
we spozed ta be tite!
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Nowata, OK
Joined Aug 2005
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Quote:
Originally Posted by cjbucher
Sorry to hear about your crash. But the good thing is that these wings are easy to build. You'll have another one ready in a couple of hours...

What kind of receiver were you using?
My flying buddy and I both run Hitec 05s' in our foamies. We live in a fairly rural area and haven't had any real issues to speak of. Although, we went to a fly-in last fall, in a more urban area and we had all kinds of issues.

Got any idea what might have cause the disaster?
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Old Mar 12, 2009, 02:19 PM
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I guess I was thinking if you were using a 2.4 Ghz receiver with a weak battery, that could explain the loss of control. 2.4 Ghz like Spektrum and Fasst require a minimum voltage to operate and will reboot if they fall below that voltage. But that would only be a problem if your receiver was not up to the correct revision on Spektrum. Example the AR6200 with v1.6 firmware has a quick connect feature to allow the receiver to recover immediately instead of scanning for channels which can take several seconds.

But since you were using 72 mhz receivers, that kinda eliminates that theory since they recover immediately on power hits. But it's possible that if the throttle stayed high and kept the voltage too low that the receiver would not recover.

Another possibility is the BEC on your ESC may have failed or overheated causing it to shutdown which would cut power to your receiver and servos...

Just a theory...
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Old Mar 15, 2009, 01:50 PM
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Quote:
Originally Posted by teslahed
I used 5mm EPP and reduced dimensions slightly to produce a smaller wing with good results. I ran a length of 4mm diameter carbon fibre tubing up each of the bits of foam used to shape the airfoil and another peice to run between them creating an A shaped frame of carbon fibre. This resulted in a wing both stiff and strong and weighing just under 9 oz all up (although only 24" wingspan).

I've uploaded a short video of me flying this wing to youtube if anyone is interested;

Scratchbuilt 22" wingspan flying wing (0 min 26 sec)
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