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Dec 17, 2004, 02:21 AM
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CactusJackSlade's Avatar
Build Log

Twin boom pusher Depron 75" 13.4 oz A/P platform


Please note, this is an old post!

I still receive many emails about this platform and since I do not have any plans the best i can do is add a bits and pieces to this thread. Hope this will help - Thanks all!


Also if you do a search of:

Posts started by "CactusJackSlade"
AND
the exact word "Depron"

You will get most of my posts about this plane, the building of it, spec's etc.


ORIGINAL POST:

Here is what I had in my mind to do with two SS kits (I posted photos about a month ago)...

I have been away from home (ok, my work shop!) for an extended period but where I'm at I had some depron, so I ordered 3 SS booms and 3 plastic parts bags...

Here is a much better rendition of what I had in mind.

75" wing span
35" from leading edge of wing to rear of tail feathers.
828 sq. in. (not including tail feathers - wing only)
Bare airframe: 13.4 oz
11" chord - "looks good to me" airfoil

The wing is folded Depron with a few ribs... it is undercambered and the tips have built in washout.

Interestingly enough, the outer wing panels (48" combined) can be slid together to replace a stock Slow Stick wing. It weighs almost the same as the Slow Stick wing and is about 5 times (or more!) as stiff!

All the "booms" are Slow Stick as well as all the plastic parts. The landing gear has been modified and now is very heavy duty and works well... especially the rear.

The "A" tail is actually hinged and taped between the panels at the top. I pull a long pin out and the whole thing can be broken down flat for travel.

I am striving for a 4-4.5 oz/sq ft wing loading when I get done.

I will be running my new 1000mw Black Widow wireless video system (still working on that) and also hope to incorperate a pan tilt set-up on the camera.

The whole objective of this project is to have a plane that will fly SLOW, FLOAT and get the camera out front... no landing gear or props to get in the way... of course if I bonk it ... the camera is in prime dorking position...

I should be up and flying by this weekend!

CJS
Last edited by CactusJackSlade; Mar 05, 2006 at 12:04 PM.
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Dec 17, 2004, 02:29 AM
Peakaboo!
Gwelan's Avatar
Keep posting on your new AP machine, it looks promising. Which motor is intended for it ?
Dec 17, 2004, 02:35 AM
Whadda YOU lookin' at?
CactusJackSlade's Avatar
I'm going to try to push it with my geared razor 300 on LiPo's... this whole setup won't weigh much more if any than my Slow Stick with my clunky digital camera... but it will have a lot more drag!

We will see... I think the key here is SLOW!

CJS
Dec 17, 2004, 03:59 AM
Registered User
Great looking plane. Love the wing. I too, am playing around with Depron wings, I'v'e built one, but it's too heavy (6ozs.)

Working hard on the MK2. For my first, I used 2mm thick Depron, but I'm seriously looking at using 1mm. (amongst other things) looking to get it down to about 3ozs

What thickness have you used ?
Dec 17, 2004, 11:30 AM
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CactusJackSlade's Avatar

Depron....


Yes, I love Depron... I have done a few 3D planes and I really like the qualities of it...

Anyway, Wellington, I used 2mm on the wing outer skin and ribs and 6mm for the spar. I had planned to use kevlar thread "struts" from the outer wing panels, down to the landing gear... but the wing is so stiff I don't think I will need it!

Yes, on the two outer panels for this plane... it will replace a stock Slow Stick wing nicely... it is incredibly stiff. I may try that swap before I even get this new platform in the air just to see how this wing flys.

I get my Depron from Depronusa.com... I didn't see 1mm, where do you get yours?

Oh, here are a few more photos:

Modified landing gear
Spar Joint using square aluminum tube
Gluing wing
Folding leading edge

CJS
Last edited by CactusJackSlade; Mar 05, 2006 at 02:25 AM.
Dec 17, 2004, 02:40 PM
RCGroups Author
SoarNeck's Avatar
Have you built something with an airfoil close to this before? I get a feeling that the stall break will be pretty potent and the AoA range fairly limited with a sharp LE like that. Nice build, mind you.
Dec 17, 2004, 03:37 PM
Registered User
I get my Depron from here :-

Sams Models - Depron

They post to the USa as well
Dec 17, 2004, 03:48 PM
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lvspark's Avatar
Sharp LE has no problems.. SPAD has proved that a thousand times.
Dec 17, 2004, 04:17 PM
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SoarNeck's Avatar
Quote:
Originally Posted by lvspark
Sharp LE has no problems.. SPAD has proved that a thousand times.
It works, but it's not like is causes NO problems. That sharp LE causes a big drag penalty at low speed, since it wrecks the high Cl performance of the airfoil (low speed = high lift coefficient or Cl for those that don't know).

Here's an example, using everyone's favorite Clark Y. The second "nose" airfoil was created by reducing the nose radius of the airfoil to 25% of the original value.
Dec 17, 2004, 06:38 PM
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CactusJackSlade's Avatar

Pointy things...


Soarneck, point noted and thanks for the input amigo.

The main reasons I went with a pointy leading edge on this one was for 2 reasons...

First was strength... a pointy leading edge allows you to use a minimal number of ribs (or none as I have done before) within the wing and second it makes for a simple wing design - one fold.

Since control of folding is a bit limited a more complex leading edge makes for more areas to have errors.

My previous pointy LE wings were for symetrical 3D planes and they behaved rather well, but that is an entirely different kind of "flying" since it's hanging on the prop most of the time!

I guess only my test flights will see how it goes! I tend to "fly by the seat of my pants" anyway!

Soarneck, now that you have peaked my curiosity about this wing shape I may just strap the two outer panels together and do a maiden on my Slow Stick...

This was one of my 3D projects... the "3DX", and this particular design flys very well.

CJS
Dec 17, 2004, 06:38 PM
I fly low, I'm in high demand
birdman11787's Avatar
I agree..... low reynolds numbers and small radius LE is not the best approach....
Dec 17, 2004, 11:30 PM
Team HeliProz
RCFEVER's Avatar
CJS,

Will the camera be mounted on the center boom, in front of the wing?

Matt
Dec 18, 2004, 02:39 AM
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CactusJackSlade's Avatar

Yes...


RCFEVER,

Correct. My plan is to mount the camera under the center boom in front of the wing.

I want the camera to be back about an inch so if I do dork it into the ground the boom will contact first at least and not the camera.

I plan to maiden the airframe tomorrow, I will then go about adding the vidi system over the next couple days... I just want to be sure the airframe is sound before installing a $500 A/V system!

I'll post more photos and flight report when I can!

CJS
Last edited by CactusJackSlade; Dec 18, 2004 at 02:42 AM.
Dec 19, 2004, 01:32 AM
Registered User
lvspark's Avatar
Quote:
Originally Posted by birdman11787
I agree..... low reynolds numbers and small radius LE is not the best approach....
We all have our own opinion, and I think that is great.

I have performed many, many tests in real life with real wings, sharp and rounded LE. In some cases, the rounded LE has worked better, but a majority of the time, the sharp worked just as good, if not better. Several times I flew my sharp LE slopers with ease while others are waiting for better conditions.

Many people have neg comments about sharp LE (including many of my club members when I first brought them out).
Now they talk about how well they fly and glide, and complain about my sharp LE wings winning the fun fly 2 yrs in a row. (with 2 different sharp LE planes)

We can slope with the best, and hover like the rest.....
Believe what you must, and calculate with your programs all you want.
We will continue to "break the rules" with our sharp LE wings..
SPAD RULES!

o.k. off my soapbox
Dec 19, 2004, 02:43 AM
Whadda YOU lookin' at?
CactusJackSlade's Avatar

So does that mean...


Quote:
Originally Posted by lvspark
SPAD RULES!
Depron is considered plastic? If so I'll jump up on a soap box too!

Hey, what is a soap box anyway? Arn't they used in derbys 'er somthing?

Anyway, I just rigged a mount for my digital still camera, so if all goes well I will do stills and video tomorrow!

CJS


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