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Old Oct 26, 2014, 07:09 AM
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United States, FL, West Palm Beach
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Build Log
The Gator Law Dart

I spent my Saturday building my first DTF scratchbuild. I need to weigh it and buy some electronics so I can see if it will fly. 30 inch by 5 inch wingspan and 30 inch fuse. 12 inch wide tail and 6 inch tall. Recommendations for added stability welcome. This is my first try so if there are fundamental issues please point them out. I've got chopsticks and rubber bands to connect the wing. Still need to split the wing control surfaces. Overall happy with my first try.
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Old Oct 26, 2014, 08:33 AM
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United States, FL, West Palm Beach
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I named it the lawn dart because it's probably only a matter of time til it goes in nose first.
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Old Oct 26, 2014, 08:39 AM
yank and bank!!
Joined May 2013
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Been there, done that, destroyed it in 5 minutes by making it too heavy.... btw what is your skill level?

You REALLY should play around with a wing cube loading calculator to see how much total weight the plane can have before trying to fly it.... I'd imagine it shouldn't weigh more than 12oz all up ready to fly.

If you don't need it to be hyper aerobatic you could build a second identical wing and join them with a CF spar and have double the wing area...

p.s. that tape could add surprising amounts of weight.
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Old Oct 26, 2014, 08:49 AM
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United States, IL, St Charles
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Love the Gator colors! I lived in hogtown from '87 to '97 and still get down there as often as I can.

I like your wing airfoil, but agree you should probably double it, and add some dihedral for stability. You could also add extensions to both ends, agled up for a polyhedral wing. take a look at Springer's OSG thread to get some ideas.
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Old Oct 26, 2014, 09:27 AM
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Originally Posted by failboat View Post
Been there, done that, destroyed it in 5 minutes by making it too heavy.... btw what is your skill level?

You REALLY should play around with a wing cube loading calculator to see how much total weight the plane can have before trying to fly it.... I'd imagine it shouldn't weigh more than 12oz all up ready to fly.

If you don't need it to be hyper aerobatic you could build a second identical wing and join them with a CF spar and have double the wing area...

p.s. that tape could add surprising amounts of weight.

I already have a spar if I need it. I was trying to start a little smaller as long as its stable. I haven't been home to weigh it yet. My in laws didn't have a scale and I built it at their house. I'll update once I get the weight. I used about a sheet and a half of DTF basically taped on both sides. Everything is joined with hot glue.
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Old Oct 26, 2014, 09:36 AM
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Originally Posted by caveeagle View Post
Love the Gator colors! I lived in hogtown from '87 to '97 and still get down there as often as I can.



I like your wing airfoil, but agree you should probably double it, and add some dihedral for stability. You could also add extensions to both ends, agled up for a polyhedral wing. take a look at Springer's OSG thread to get some ideas.

I grew up in Gville, 81-2000. Left for the military and haven't been back much. Big fan, even with the current slump.

It's loosely based on the Experimental Airlines Axon minus the angled front and rear. Always easy to add for a bigger plane. Or maybe I could join two 20" wings. I don't want to get ridiculously big though. The area close to me is suited for smaller planes, not a big 60" beast. Thinking about keeping this one kind of slow as a trainer/entry to acrobatic maneuvers.
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Old Oct 26, 2014, 11:28 AM
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United States, WA, Vancouver
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The requirement for stable is a high wing ( you've got that ) and either dihedral or polyhedral ( wing ends angled up ) .

The requirement for slow is light wing loading ( wing area RELATIVE to overall weight ) . To get light wing loading you want MAXIMUM wing area and MINIMUM weight . In my opinion , for flying in a small space it's better to have a SLOW flying plane - not necessarily a smaller plane .

And if you think you'll be lawn darting , why not set it up as a pusher ( motor/prop on top behind the wing ) so the motor/prop are not the first thing to hit the ground ?

Here is an example of LIGHT WING LOADING , at the end it's going so slow that I can walk alongside for a close-up .

Lightweight 40" wingspan FT Old Fogey-ish (2 min 58 sec)
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Old Oct 26, 2014, 12:10 PM
yank and bank!!
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Originally Posted by balsa or carbon View Post
Here is an example of LIGHT WING LOADING , at the end it's going so slow that I can walk alongside for a close-up .
Very nice
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Old Oct 26, 2014, 12:54 PM
Hot glue held together by foam
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Very nice
Thanks !
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Old Oct 26, 2014, 01:07 PM
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B or C: That thing is crazy slow! Pretty cool to see.

I'm thinking about a pusher. I think I could accomplish it by stacking another piece of fuselage on top of what is there. It truly would become an Axon or something very close.

Update on the weight: it's 6.6 oz / 186 grams as it is. I think I'm going to use hxt900 servos at 9 grams each. I'll start digging on the weight and if I have enough wing surface.
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Old Oct 26, 2014, 01:24 PM
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Just ran the numbers. I think I'm going to need a bigger wing according to this site: http://www.ef-uk.net/data/wcl.htm

150 sq inches of wing (30 x 5) at 16 oz gives me a WCL of 15 which is in the racer range. It's all a learning process though. I had no idea what the weight would be before building it. I will probably just hang onto this wing to use it with something smaller later. I can't add a spar to it because the foam inside wasn't set up for it. Maybe something in the 40 x 6 or 50 x 6 range would work?

Now that I'm home on my computer instead of my phone I will look up Springer's OSG.
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Old Oct 26, 2014, 01:42 PM
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Wow, the OSG looks so much more complicated!

I should look into what battery I want to use, I could definitely slim down my fuse to save weight.
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Old Oct 26, 2014, 02:44 PM
yank and bank!!
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It wouldn't be very hard to select 7oz of electronics and keep the loading down somewhat....
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Old Oct 26, 2014, 03:12 PM
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I've been looking and it's very doable. But that would make it pretty sporty. I think the best answer is to just build a bigger wing. It's easy enough. Making the wing was actually much easier than I thought it would be.
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Old Oct 26, 2014, 03:29 PM
Hot glue held together by foam
United States, WA, Vancouver
Joined Aug 2010
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A good way to keep weight down is to put your ESC , receiver and servos as far to the front as possible , so you can get the CG balance with the lightest possible battery ( also placed as far forward as possible ) . Just run pushrods from the servos back to the elevator/rudder .

Al

Here is a video of the plane ( EzFly pusher prop ) in the photos below , also with light wing loading for slow flight . This is the plane I use to teach first timers .


Copy of EzFly with under-cambered wing (1 min 57 sec)
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