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Apr 09, 2018, 03:36 PM
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rotagen's Avatar
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I would give the MPF foam a try if that's what you have available, not sure of its properties since I haven't used it at least I don't think.

You might even be able to do it as one-piece like the Flite Test guys do a lot of their planes, curving it tightly to make the leading edge? One thing I do for a quick light leading edge sometimes is hot glue a colored plastic straw to the front of the wing, works great.

I have only one experience making a plane that way, it was the "synapse" wing, if U do a youtube search. It's a cool design using DT foam with the paper left on. and wrapped with colored packing tape....but mine did come out too heavy in my opinion - it flew, but slow to gain altitude and slow to respond. Probably because I tend to use lighter motors and batteries and simply didn't have enough power.

One of my first planes- a simple parasol wing had colored packing tape as the top wing layer, back when I only had brushed motors, not the prettiest but that thing flew great and floated forever.

I have some kind of waterproof construction paper that I will try if I run out of depron...

but I would try what you have, or even go with a simple KF wing (fill the space in front of the spar on top with another layer of foam)... that one flew OK and my wife thought I was nuts messing with it.

I should add that template for an optional KF piece - I will try to later, but if you extend the spar line with a ruler on your template you can mark it on foam before cutting.

I also forgot to mention the size CF tube spar I used - it was 3mm square-shaped hollow tube from Hobby King I think.

1/4 inch skewer should work great, it would probably be real close to the same weight.

I tried to make a tiled version of the plans using a free "pdf tiler" program but then when I test printed the lines don't match well - just using adobe reader on that full size guy and letting it print the tiles works better.

Keep us informed how it goes, I really like the cutlass, I think it's the perfect design for both slow and fast speed!

As usual, I'm talking too much.
Last edited by rotagen; Apr 09, 2018 at 03:50 PM.
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Apr 10, 2018, 02:29 PM
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rotagen's Avatar
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Revised Plan - Cutlass

Revised plan posted. Added to post #1.

Included KF wing option template, fixed some line issues (nothing major) , resized servo box to HXT 500 size,

Moved servo box to actual location for wire distance, added more details, learning sketchup.
Last edited by rotagen; Apr 15, 2018 at 02:19 PM.
Apr 15, 2018, 02:22 PM
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**Plan Revised again to add a bit more detail - included cut lines in wing upper surface around verticals and tail brace.

To save people time on measuring.

Latest/Greatest Posted to post #1.

Older one Removed from the last post and the new one posted here as well.

I'll get better at this stuff in the future guys...
Oct 17, 2019, 02:28 AM
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Rather than start a new thread, here is an alternative foam build..I moved the motor to the front on this one and added nose wheels on an X frame ..
Span is 24" made from 8mm EPP ..

Its let downs are the fins and rudders... the fins are floppy...
and there is a mess of servo extension wires under the model.. all taped over , but untidy

weight 6.4oz .....6A ESC.. 3x tgy1440a servos.. R410x receiver
Horizontal area 1.6sqft... a 4ozsqft loading.... just about low enough for indoor flight for me..
Last edited by davereap; Oct 18, 2019 at 02:34 AM.
Oct 18, 2019, 01:04 AM
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My cutlass got a lot of good comments... but it had no elevator authority when flying indoors..
the elevons are just too small for slow speed flight.. the airflow from the prop does not go over them, and at the speeds we fly they had zero effect..
I tried moving the COG to get more response, all that achieved was for the nose to go up high with no improvement in elevator sensitivity..
I will have to rethink the whole design..

Here is a revised design for full spread elevons and at 28" rather than 24" hopefully this will work better.. It should lower the wing loading
When I started cutting I found that the foam I had was just a bit short for the full wing, the stencil was about 1.+inches too long at the nose..
Rather than join bits on, I have simply left it short,, and will move the fuzz back to fit..The nose is over long in any case with a front motor stuck on the end.
Last edited by davereap; Oct 19, 2019 at 01:04 AM.
Oct 20, 2019, 11:55 AM
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All done... 28" span.... the wing loading has been reduced despite using a bigger motor and having a bigger span.. the new motor puts out about 10oz thrust on 2s..
2204-1800 motor.. 8x4.3 gws type prop..6A plush esc.. 3x tgy 1440a servos. 6ch RX..
AUW 7.5oz ..3.4 ozsqft loading..
Nov 01, 2019, 06:02 AM
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It worked fine this time, plenty of control..but my COG calc was way off.. the lipo needs to get a lot further forward..
for next week I will have my battery velcro strip repositioned..

NOTE.... this model just wont fly correctly, despite it now having a forward COG when you get its nose "up" it just continues to go more and more nose up... very annoying... I am binning the thing...
I cant be bothered with a model thats a pain.

note the picture at the front of this video is from the first build that just would not fly correctly
latest cutlass getting there (1 min 45 sec)
Last edited by davereap; Nov 16, 2019 at 03:03 AM.

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