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Old Mar 16, 2012, 02:02 PM
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United States, MI, Oakland County
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Thanks for all the input. Will spend this weekend deciding which way to go for my first try at a scratchbuild.
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Old Mar 18, 2012, 10:07 PM
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Virginia Beach, Virginia, United States
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I hope to finally start on some skyvan plans tomorrow!!! Flying real planes has gotten in the way of things lately!! Hope to have something to post this week sometime!!!
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Old Mar 20, 2012, 11:26 AM
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Thanks Ed for your inspiration. I bought a case of $tree foam and started putting stuff together. Here is my build log of what will eventually be turned into a twin otter. http://www.rcgroups.com/forums/showthread.php?t=1617465

The only thing I did differently is the way I built the wing spars. (by mistake at first) the bottom layer is 3" then the 2 1" stips sandwiching the arrow shaft and topped off with a 2" strip. For me it makes the interior more semetrical since its stacked nicely and makes me feel better.
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Old Mar 20, 2012, 12:10 PM
Ed @ Experimental Airlines
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United States, AZ, Phoenix
Joined Sep 2011
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ducoop - looking good! The Twin Otter is one of my favorite planes and I have many skydives out of them.

By all means do take creative liberties with the construction. You'll see many of mine are actually a little different from one another too. I just picked a logical instruction for the videos since some guys like to have a discrete plan to follow. Sometimes accidents lead to great discoveries.

Be sure to post the final outcome of your project back here on this thread.

Peace,
Ed
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Old Mar 21, 2012, 07:46 PM
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Anyone know of a local source in East Valley (AZ) for the colored box-tape/packing-tape? I tried Wal-Mart, Michaels Hobby Store, Staples,and Office Max. Wanted to pick up a cpl rolls to use while waiting for online source to arrive.

Thank you,
Raymond
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Old Mar 21, 2012, 08:18 PM
Ichy to Build and Fly.
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United States, FL, Davie
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Quote:
Originally Posted by Golddrakken View Post
Anyone know of a local source in East Valley (AZ) for the colored box-tape/packing-tape? I tried Wal-Mart, Michaels Hobby Store, Staples,and Office Max. Wanted to pick up a cpl rolls to use while waiting for online source to arrive.

Thank you,
Raymond
Hi Raymond

I got my tape from www.fast-pack.com

Very good and you get 8 colors for 12 $ or so

Hope thIs helps

Thanks
Mosaic
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Old Mar 22, 2012, 06:18 AM
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United States, OK, Ardmore
Joined Sep 2007
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Plane plans

Have any of you visited the Spad ToThe Bone website? They have a free plans for a lot of planes. A lot of the planes could be built using (Ed's) Experimental Air
Techniques.
I have built a lot of the planes using the plastic gutter pipe and coroplast materials. They use glow engines.It could easily converted to the DT Foamboard for electrics.
Just another ideal to build a lot more planes.
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Old Mar 22, 2012, 08:25 AM
Ed @ Experimental Airlines
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Originally Posted by airman1958 View Post
Have any of you visited the Spad ToThe Bone website? They have a free plans for a lot of planes. A lot of the planes could be built using (Ed's) Experimental Air
Techniques... Just another ideal to build a lot more planes.
If you like maybe pick a few you think would work well with DT foamboard and post them (or links) here to give guys some build ideas.
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Old Mar 22, 2012, 08:27 AM
Ed @ Experimental Airlines
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Quote:
Originally Posted by Golddrakken View Post
Anyone know of a local source in East Valley (AZ) for the colored box-tape/packing-tape? I tried Wal-Mart, Michaels Hobby Store, Staples,and Office Max. Wanted to pick up a cpl rolls to use while waiting for online source to arrive.

Thank you,
Raymond
Sorry man, I have never seen this stuff in the stores, north or east valley or otherwise. Clear packing tape is OK for practice if you're itching to build a quick chucker for this weekend. You can always Sharpie some art on the foamboard and clear tape over that.
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Old Mar 22, 2012, 09:49 AM
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OK, thank you very much Ed. Have tape coming from online sources, but like a kid at Christmas...LOL

And THANK YOU so very much for the time and effort you've put into creating the videos, instructions and the knowledge you've shared with us. I have yet to fly anything, but this thread and your videos are simply awesome; and when factoring in that you're doing all this just to share what you know with others, it's just so cool!! Thank you, thank you, thank you!!!
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Old Mar 22, 2012, 12:13 PM
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United States, MN, Maple Grove
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RCDad - there are some kind of so-so steel L-brackets for framing (as in studs) that are thinner, still pretty heavy, but worth comparing to the aluminum. License plate aluminum was a cool idea. You might also want to go somewhat bigger with that prop, like at least 8 or 9 x3.8 or x6. That's a pretty torque-y motor. 9x6 is the actual recommended. Unless you're putting it on an Axon, in which case I would think about a 3-bladed 6x5 or 6x6.
Ed, posted in the Motor forum on what to do as well, but wanted your thoughts. I am building the Axon so am limited in prop size. I could not find a 6X6 so I decided to use the Turnigy 3530-1100 on a retro mod for our Super Cub.

This is the motor I have chosen and will try to squeeze a 7X6 prop on there.

Heads Up RC 3536-14

It will give me close to 100 watts per pound, but won't be a screaming banshee. Does this look like a decent fit for the plane? As a reminder, doing the Axon with a 60 " wingspan and slightly larger tail feather section.

Thanks RC Dad
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Old Mar 22, 2012, 12:25 PM
Ed @ Experimental Airlines
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RC Dad - that sounds like a winner. Though not ideal, you could trim and balance the prop for clearance if needed, but a straight 7x6 seems like a good spec for that motor as far as I can tell. Maybe even a bit quieter than the 2200kV with 6x4. Keep us posted.
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Old Mar 24, 2012, 03:07 PM
Just FPV'n
Orange County Ca.
Joined Feb 2009
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Is AC aft of CG?

Ed,

In your Noob tube video you touch on how you find the CG of a model aircraft..

According to the video... AC of the wing ends up being directly over the CG of the fuselage???..
The AC is generally aft of the CG right??
Is there a "rule of thumb" percentage of how much aft the AC should be behind the CG??

Thanks Mike
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Old Mar 25, 2012, 08:37 AM
Ed @ Experimental Airlines
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Originally Posted by Mykro View Post
Ed,

In your Noob tube video you touch on how you find the CG of a model aircraft..

According to the video... AC of the wing ends up being directly over the CG of the fuselage???..
The AC is generally aft of the CG right??
Is there a "rule of thumb" percentage of how much aft the AC should be behind the CG??

Thanks Mike
You are right, the AC must be aft of the CG. The method I showed is admittedly very rudimentary and was really just meant to show a simplistic way of putting the CG over the thickest, most cambered part of the wing, which is at 30% in this wing design. The rule of thumb is CG 25-30% aft of the leading edge.

That leaves out a lot in regards to discussing the AC, like the wetted area created by the fuselage and tail, the actual center of lift of the airfoil vs. the aerodynamic center of the wing, which will usually be at slightly different locations. In this flat bottom wing the CL is probably somewhere between the AC of the wing (half-chord, geometric center) and the highest cambered location. And then the tail contributes even more toward pushing the overall AC aft (considering only stability in flight, not lift per se)

I actually prefer to use fingertips or similar to balance CG on finished planes but for depicting the wing mounting on the Noob Tube relative to the CG I came up with the kind of half-assed idea I showed. Not very sophisticated, kinda works for beginners.

But to emphasize, in the end you are 100% correct that the overall AC must be aft of the CG for longitudinal stability. Sorry I didn't depict that very well, and left out some details.
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Old Mar 25, 2012, 09:46 AM
Just FPV'n
Orange County Ca.
Joined Feb 2009
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Quote:
Originally Posted by ExperimentalAir View Post
You are right, the AC must be aft of the CG. The method I showed is admittedly very rudimentary and was really just meant to show a simplistic way of putting the CG over the thickest, most cambered part of the wing, which is at 30% in this wing design. The rule of thumb is CG 25-30% aft of the leading edge.

That leaves out a lot in regards to discussing the AC, like the wetted area created by the fuselage and tail, the actual center of lift of the airfoil vs. the aerodynamic center of the wing, which will usually be at slightly different locations. In this flat bottom wing the CL is probably somewhere between the AC of the wing (half-chord, geometric center) and the highest cambered location. And then the tail contributes even more toward pushing the overall AC aft (considering only stability in flight, not lift per se)

I actually prefer to use fingertips or similar to balance CG on finished planes but for depicting the wing mounting on the Noob Tube relative to the CG I came up with the kind of half-assed idea I showed. Not very sophisticated, kinda works for beginners.

But to emphasize, in the end you are 100% correct that the overall AC must be aft of the CG for longitudinal stability. Sorry I didn't depict that very well, and left out some details.
I had never thought of balancing the plane the way you showed in your video..
For me it was always by trial and error until I got my planes balanced just right..
The way you showed how to balance the plane really narrows it down... It's a common sense way of balancing a plane from a scratch builders perspective.. Nice job Ed...
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