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Old Jun 19, 2006, 07:26 AM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
Build Log
BluCub2, The Next Generation

I decided to expand my Cub design, fom the original BluCub which is a simple profile rudder/elevator plane. This one uses 'OTF' technology (On The Fold) for a full fuse.

Here's one of the video's.
And another

The same thing can be used for wings, but I stuck with the tried and tested 4-40 airfoil here (4% thickness / 40% peak).

I also went for the combined wing strut, landing gear rods, using .080" (2mm) which extend from the wing, through the fuse to the wheels. Very strong and light, and won't snap off like carbon fiber.

Ailerons on high-winged planes present a challenge. The problem is adverse yaw, which means the plane yaws in the opposite direction of the roll. This is great to hold the nose up in a turn, but actually makes it almost impossible to turn. The nose winds up going up until you are in a hover. ANyone who has seen this problem can attest, it's a bear. The solution is to use differential aileron travel.

There are several ways to accomplish the required differential:
- Mechanically set the servo arms so that there is almost no down travel on the ailerons.
- Use 2 servos mixed on seperate channels and program the differential in the radio.
- Use 2 servos and a Y-connector, and mechanically set the arms so there is minimal down travel.

I have some pictures of the way I did the 1st 2. The 3rd is basically like the 1st. It takes some playing with it, but is well worth the time.

Here are some build pictures and the plans. I posted these on the original thread, but thought this deserved a thread of it's own.

Here's the first installment... More later!

Edit: Added plans for a 40"ws version for geared 400. Not tested, but should be fine!

Edit: Added 48"ws full-fuse plans. Flies great!
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Last edited by Gene Bond; Jan 09, 2010 at 06:05 AM. Reason: Added 48"ws plans
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Old Jun 19, 2006, 10:18 AM
Gravity is my downfall
Tailspin Ken's Avatar
El Mirage, Az.
Joined Oct 2003
733 Posts
Gene,
When you weigh it down, how many full cans are in the Coors case?
This looks great! I think this would be a really fun plane to build and fly. Thanks Gene!
Ken
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Last edited by Tailspin Ken; Jun 19, 2006 at 06:15 PM.
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Old Jun 19, 2006, 11:42 AM
Registered User
Beaverdam Creek, VA
Joined Aug 2005
2,322 Posts
Well, you need less weight to hold it as time passes...

Good Luck!
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Old Jun 19, 2006, 01:29 PM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
Thanks, guys... (Cans, not bottles, sorry! )

Let's see where did I leave off?

The controls for the tail have to be routed before the wing is glued on, since access will be all but imposible. The access through the hatch is very limited.

The way I do it is to use the rods to drill a hole. It may take a couple tries to get close. Once close, I heat up the rod with a lighter to open up the hole slightly.

Glue the rear-fuse top in place once the control rods are in place. It goes down in between the sides of the fuse.

The H-stab/elevator and V-stab/rudder can be attached now as well. Simple tape hinges are fine, and what I use on the elevator. For the rudder, I like to slot the hinge and use 1/4x1" strips of transparency film. I use hot glue for setting them.
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Old Jun 19, 2006, 01:40 PM
Too little play time...
WarrrEagle!'s Avatar
South Alabama
Joined Feb 2005
1,500 Posts
Gene, did the v-stab on your blue one prove to be too small? I noticed that white one and the plans show a larger one... I like the scale looks of the blue version better.

Thanks for what will be my first full fuse blu core foamie. (Sorry STS... Gotta have a yeller Cubbie!)
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Old Jun 19, 2006, 01:40 PM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
Assuming the wing is cut out and the ailerons are hinged, it's time to roll a little airfoil in. With Fan Fold and some other softer foams, you can easily roll it on the rounded edge of a table or counter top. For more brittle foam, like the Celfoam 88 I'm using in the whit version here, it will crack if you are not careful!


so... Build a Bendfoam Jig or use a mailing tube or similar and some masking tape as shown. A little heat is required to help soften the foam so it will surrender to your wishes.
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Old Jun 19, 2006, 01:43 PM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
Quote:
Originally Posted by WarrrEagle!
Gene, did the v-stab on your blue one prove to be too small? I noticed that white one and the plans show a larger one... I like the scale looks of the blue version better.

Thanks for what will be my first full fuse blu core foamie. (Sorry STS... Gotta have a yeller Cubbie!)
Yup, part of the adverse yaw correction, as shown below with the 'R&D spy photos'
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Old Jun 19, 2006, 02:08 PM
Krued Up
snolord1's Avatar
United States, MA, Springfield
Joined Jul 2004
4,313 Posts
i'm in
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Old Jun 19, 2006, 02:13 PM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
If you are using a single servo, I would suggest putting right on top, even though it's uglier. This is another good reason to use 2 aileron servos. If you put it under the wing, as shown on the blue one here, it's almost impossible to adjust later. I got PO'd and pulled it out to put on top as shown in later pictures.

So, either way, the wing can go on now.

Mark and center it, making sure the wing is square and the tail is square, etc... and glue it to the top of the fuse.

The struts are very important, as there is no other wing bracing. I used 2.3mm (.090") fiberglass rods from BP They are also available in cheap kites at WalMart, and kite shops on-line. The will not snap like carbon fiber Use plenty of hot-glue and make sure they are buried in the wing almost all the way. I snake them in from underneath, through the fuse, so the ends of the rods where the wheels go is just ahead of the LE of the wing. The 14" length is perfect for me, for a 9" prop with 2" wheels.
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Old Jun 19, 2006, 02:21 PM
Too little play time...
WarrrEagle!'s Avatar
South Alabama
Joined Feb 2005
1,500 Posts
Thanks for the answer...

Also, do you peel your blu core? Both sides?
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Old Jun 19, 2006, 02:31 PM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
As you can sorta see in the previous pictures, the axles are bent from music wire, and lashed with floss and CA'd to the fiberglass struts. Pieces of small fuel tubing are used to secure the wheels.

If you want to do floats, you will need some rear support. I came up with a removeable solution that works well if you don't crash too hard.

Take a couple of skewers, and 'crack' about 1/4" back from one end as shown. Saturate the crack with CA. These will slip into a plastic tube that is set in the fusealge, and they are held in with a rubber band.

The floats, I cut with a hot-wire. It took several tries to get them right, and a lot of discussions on the BluBeagle thread with viking60 has definately helped. He has a great web page for float design, btw.

I covered these with packing tape, but the ones on the white version, I covered with Doculam. It is much nicer to work with and lighter, if you have a covering iron. Here's one source.
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Old Jun 19, 2006, 02:33 PM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
Quote:
Originally Posted by WarrrEagle!
Thanks for the answer...

Also, do you peel your blu core? Both sides?
Peel the inside of the fuse, leave the film on both side of the rest...

I didn't use fanfold for either of these. the Blue stuff is some type of similar-to-Depron substitute, like RCfoam... A semi-local guy sells it and I tried it. Slightly heavier, but not bad, and a good finish one side.
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Old Jun 19, 2006, 02:52 PM
Too little play time...
WarrrEagle!'s Avatar
South Alabama
Joined Feb 2005
1,500 Posts
Quote:
Originally Posted by Gene Bond
I didn't use fanfold for either of these. the Blue stuff is some type of similar-to-Depron substitute, like RCfoam... A semi-local guy sells it and I tried it. Slightly heavier, but not bad, and a good finish one side.
Ahhh, OK. Looks like a nice surface.
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Old Jun 19, 2006, 09:12 PM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
As I mentioned earlier, aileron differential travel is very important to minimize adverse yaw.

Below are some shots showing the center and full travel limits of the aileron servo, using a single servo. You can see I used a 90 arm. This results in almost no down travel on the outside aileron.

To get a decent 90 arm, I wound up clipping other arms off and lashing with floss and CA, so they would have even hole spacings.
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Old Jun 19, 2006, 10:29 PM
Too little play time...
WarrrEagle!'s Avatar
South Alabama
Joined Feb 2005
1,500 Posts
I was trying to visualize the aileron thing... THANKS!

Will it roll like that?
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