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Old Oct 25, 2010, 05:51 AM
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Blu-Beetween - a FFF version of the Bee-tween

Hello,

The thread will document the design and build of a FFF version of Randy Randolph's 1/2A Bee-tween model. As I understand it, the plans were originally a free pull-out from Model Airplane News... from July 1991? It's a simple low wing 3ch RET plane with a square fuse and clean lines.

Hexode did a mini-review recently, you can find more information and photos of the original balsa model here:

http://www.rcgroups.com/forums/showthread.php?t=1194085

So nearly 20 years later, here is an updated version built with FFF and electric power. I have made a few changes along the way including lengthening the nose, adding a simple foam monoblock, and a KFM2 wing variant.

Enjoy!

Updates:

Nov 28, 2010: v0.1 'beta' plans posted
Dec 3, 2010: v0.2 beta plans posted - Increased to 2" monoblock, minor fuse modifications
Dec 4, 2010: Correct error with stab in v0.2 plans.
Dec 5, 2010: Uploaded KFM2 Plans, added CG marks.
Dec 12, 2010: v0.3 plans posted - Updated with misc build details.
Mar 17, 2011: v0.3 A4 sized plans added
April 3, 2011: Clark-Y plans pulled pending changes after flight #2.

Flight Reports:

Clark-Y Maiden Flight Report: http://www.rcgroups.com/forums/showp...&postcount=291
Clark-Y Flight Report #2: http://www.rcgroups.com/forums/showp...&postcount=314
Clark-Y Flight Report #3: http://www.rcgroups.com/forums/showp...&postcount=320

Setup Data:
Rudder Throw: Lo 1/4"U - 1/4"D, Hi 3/4"U - 3/4" D
Elevator Throw: Lo 1/8"U - 1/8"D, Hi 1/4"U - 1/4" D
Clark-Y CG: 30% (2" from LE)
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Old Oct 25, 2010, 07:16 AM
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It's just a plane.
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Looks interesting - subscribed.
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Old Oct 25, 2010, 11:54 AM
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I think I can glue that..
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I'm in
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Old Oct 25, 2010, 12:42 PM
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Cool little plane, Still have the free plans though there are a few hundred pin holes in them. They preformed well with an .049, what motor you thinking of ??
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Old Oct 25, 2010, 12:59 PM
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Quote:
Originally Posted by Denile View Post
Cool little plane, Still have the free plans though there are a few hundred pin holes in them. They preformed well with an .049, what motor you thinking of ??
I have a 'photo' of the plans. It was good enough to get started.

If I can keep the AUW under 12oz, then the venerable Blue Wonder 1700kv is my motor of choice. I personally intend on using the Infinite A1709-1500. She's a small diameter motor that should fit behind the cowl I plan on making.
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Old Oct 25, 2010, 03:19 PM
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philipa:
You will have a great flying plane with your plans. I have a B-Tween hybrid, it uses the old built up balsa wing from the original 1/2A Cox Black Widow powered plane that had sat on the shelf forever. The fuse was oil soaked and busted up so about 3 years ago I made a foam fuse out of Hobby Lobby (the craft store) foam board core. Mine is powered by a HiMax 2015 geared inrunner about 5 to 1 ratio. Puts out about 90-100 watts and performs great, kind of overpowered really. I have flown it with a brushed GWS 350 C gear on 2 cells also and it is a great small field flier.
All up weight RTF--15ozs
Prop to leading edge of wing--5inchs
TE of wing to stab hingeline--12inchs
Total length--28inchs
Will post a pic later, batteries are dead in the camera, Go Figure.....

BTW the dihedral will look like a lot on the bench but Randy knew what he was doing, The plane turns like it has ailerons, they just dont like to fly inverted, but will barrel roll easily.

Good Lusk
Bob
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Old Nov 09, 2010, 07:07 PM
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Thanks for the dimensions soar-ne.

I haven't had time to touch the plans for the past week. I'm struggling with the smaller 34" WS... the plan was to keep is lighter but I don't think it'll save much weight... and it'll likely end up increasing the wing loading.

I think I will revert back to the original 37" wingspan as per the original design. I'm hopeful she'll stay under 14oz AUW.
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Old Nov 28, 2010, 01:40 PM
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Updated plans in post #1.

I have included both Clark-Y and KFM2 wing variants. I don't plan to build the KFM2 version but have included it for those FFF builders out there.

Next up is the Beta build!
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Old Nov 28, 2010, 05:14 PM
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Just found this thread Philipa. I was just looking at a pic in an older mag that featured a few hundred plans. This was one of them. Old style, RET, dihedral... yup, you know what I like.
I will be anxiously awaiting the Beta Build.

Jimmy
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Old Nov 28, 2010, 05:21 PM
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Here is a link to the original plans/MAN article along with a step-by-step build of the balsa version:

http://www.rcgroups.com/forums/showthread.php?t=846256

Obviously scanned/photo but it's what I used for the design.
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Old Nov 28, 2010, 05:34 PM
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Just a few points about the beta plans:

- The wing incidence for the Clark-Y version was a pure guess. I tried to replicate the plans but I won't know if it's correct until I maiden her.

- The nose is not true to scale. I chose a more squared off design for a couple reasons: 1) To allow fitment for the Blue Wonder motor, 2) So that I could later fabricate a cowl using the pop bottle/heat gun method. Those who lack those skills/resources can simple extend the upper and lower fuse to close in the gap a bit for a cleaner look.

- The nose is extended from the original plans to help with CG. I used the dimensions soar-ne provided. I've also chosen a top mounted battery arrangement with generous room for CG adjustment. Overall length has now increased to about 25" from the stock 22-1/4"

Cheers!

Philip
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Old Nov 28, 2010, 07:48 PM
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Philip,

I really like the look of this bird. I'm looking forward to hearing about the results of your build.

What sort of behavior do you expect from this airplane? I have only flown the high-wing models, so a low-wing jobber like this is new territory. Big dihedral, so I think she would be stable...

Clark-Y would be interesting, can you point me to a link where one is built up with FFF?
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Old Nov 28, 2010, 08:34 PM
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Quote:
Originally Posted by ruff1 View Post
Philip,

I really like the look of this bird. I'm looking forward to hearing about the results of your build.

What sort of behavior do you expect from this airplane? I have only flown the high-wing models, so a low-wing jobber like this is new territory. Big dihedral, so I think she would be stable...
It should be stable. I've heard nothing but positive reports about the flight stability of the Bee-tween and similar low wing RET models.

You might be waiting awhile for the maiden though. The weather has turned cold up here... winter is well on it's way. Unless we get an amazing warm spell come January, this bird won't see air under her wings till March/April sometime.

Quote:
Clark-Y would be interesting, can you point me to a link where one is built up with FFF?
A Clark-Y with such a small chord would be difficult to from from FFF. For simplicity using FFF, I would just cut a KFM2 wing.

I have been playing with my hot wire foam cutter. I now cut my own wings using airfoil templates from the World of Krauss:

http://worldofkrauss.com/

I've done a few already and I'm quite pleased.
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Old Nov 28, 2010, 08:39 PM
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This is what I love about building foamies... the instant satisfaction of cutting some foam and assembling a fuse in an hour or less!!! I couldn't help but tape everything together for a dry run! All I need to do is prep the surfaces and glue.

Boy, she is very streamlined! There isn't too much room for gear:

- Servo's are mounted upside down and accessed from under the removable wing.
- The removable forward turtle deck allows access to the battery.

Note: The foam block in the foreground is a spare monoblock I made. The other is already placed inside the plane. It's an intricate piece with lots of curves. Thankfully I have a vertical hot wire scroll saw!
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Old Dec 01, 2010, 10:18 PM
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Well, the Beta build did not go as expected. A few issues:

1) The battery compartment is far too tight. There is no room for wiring as the battery takes most of the room (esp. width) and ESC placement is tricky.

Solution: Increase monoblock width to a full 2"

2) The fuse looks a little 'squat' compared to the photos I've seen

Solution: Raise overall fuse 'height' by about 1/2" or so.

3) The fuse near the tail seems a bit on the flexible side.

Solution #2 should help.

I have pulled the plans in post #1 for the time being until I revise them.
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