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Old Nov 30, 2012, 02:57 PM
treefinder
springer's Avatar
SE MI
Joined Oct 2004
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Do a KFM5a wing. Mine on my 42" BB has survived all sorts of ignominities for 5 years! It has a 1/8" dowel steam bent at LE, and skewers just behind the step, and at TE (they are about 10" long). The LE one is full span (i think, it's buried in the foam) The bottom step piece is gorilla glue laminated to the main wing, and the LE is sanded round and wrapped with packing tape. The wing is still flexible, but hasn't fractured so far.

Tried to post the link to a pic in my blog, but it doesn't seem to work. So click on my username and scroll down the blog about 3/4 the way down. there is a picture of the wing on the plane(in 2009), and one of the removeable saddle I made so I could use a KFM3 wing along with the original KFM5a.
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Old Dec 01, 2012, 12:49 PM
Gravity: it's the law
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United States, NC, Mooresville
Joined May 2011
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Hi

New to this thread and relatively new to scratch building. I built 2 wings with FFF (one Zagnutz with smaller dimensions and a Divinity), which fly quite decently. But my attempt to build an EZ Cruiser didn't end up so well. I had trouble finding a good CG position and when I did the wing collapsed and it ended up in a few pieces. I concluded a profile type of plane was not adequate for my abilities (building and flying)

I got very intersted in the BB33 and want to build one to teach my son to fly. I already cut the FFF according to the plans on the first post, I am building with a 2" monobloc (sandwiched white foam). I have a couple of questions I hope you guys can help. Bear with me if any stupid one... I did look in the thread for answers, but as long as it is now, I couldn't find much

1) I cut everything according to the plans, but the wing is shorter than the saddle. If I align the LE, there is a 1/4" distance between the TE and the end of the wing saddle. I initially thought the rear bulkhead would fill that gap but it is supposed to align underneath the rear "stop" of the saddle. Am I doing something wrong?
2) The slot in front of the monobloc is supposed to house a stick mount, right? Any suggestions how to do that (most of the pictures here show a firewall mount)
3) Any guidelines to mount the servos? Should I use a balsa tray, a FFF tray or are there other better suggestions?

I do appreciate you guys sharing your experience.
And thanks to Tony for a great plane!

Walter
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Old Dec 01, 2012, 06:51 PM
treefinder
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Not sure about question #1, but if you are doing the undercamber wing, I'd add a skewer to the LE and TE (full span LE, and at least middle of span on TE). Gorilla glue and wrap with packing tape. Makes wing much stronger and takes up the "extra" space!

On #2, I suggest you do a firewall mount. With that, one can make thrust line adjustments which may or may not be required, but with the stick mount you are stuck with how it came out. I've built several BB's from 24 to 42" spans and find that down thrust is something that ultimately is unique to each plane, so being able to fine tune it is a bonus. The face of that part of the monoblock is angled for the correct down thrust if i recall correctly, so just glue a piece of light ply or bass to it to mount the motor.

#3 I've used popsicle sticks cut to the inside dimension of the fuse (probably 2" at the point where you would locate them), gorilla glued them to the right location, either on little foam stands or on notches cut into the monobloc, and screwed servos to them. Originally I just hot glued them in, but found I do too much swapping so it's easier to remove/replace with the screw mounts. On later builds, I cut themonobloc shorter and used a shelf of fff to extend to the wingTE bulkhead. With that I cut 1" x 1/2" holes and glue the popsicle sticks to front and back of them then pop the servos in. this link is to a page for a different plane, but the top right pic shows how I mount servos in general. http://www.rcgroups.com/forums/showp...&postcount=109
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Old Dec 01, 2012, 08:56 PM
Gravity: it's the law
Wally_in_NC's Avatar
United States, NC, Mooresville
Joined May 2011
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Thank you Springer
I am more or less set on a firewall (I asked in case there was a much better solution with the stick), I will just have to glue a block of foam to the front of the monobloc, since my motor is short (this one). My monobloc didn't turn out so pretty, so I lost the angle, I can redo it with the block. And I might just put some foam to fill the slot, which I realize I shouldn't have cut.

The servo mounting you did seems easy and strong, I am going for it

I already added Fibergalss rods to the wing, so I should be good there. But my problem is not underneath it, it is behind the TE (or would be in front of the LE if you mounted it all the way back, but that seems even worse). It is like the wing is too short for the saddle.
I think I will just put a piece of FFF there, so the TE will rest against it. Next build I will check that before cutting.

Thanks again. I will try to post pictures when done (I just removed the clamps now, it seems to be glued OK, although I have a slight misalignment in the back, despite I checked it 3 times).
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Old Dec 01, 2012, 09:01 PM
Slipping the Surly Bonds
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Attica, MI
Joined Dec 2006
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Yes, for servo mounts, especially with your 2" wide monoblock, popsicle stick rails mounted through the fuselage sides just behind the monoblock is a good position. Did this for many Oshkosh Specials.

Simple, yummy, and effective.





Ken
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Old Dec 01, 2012, 09:28 PM
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United States, NC, Mooresville
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Looks good!
What foam do you use for the monobloc?
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Old Dec 01, 2012, 09:33 PM
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Old Dec 01, 2012, 09:52 PM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
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Quote:
Originally Posted by Wally_in_NC View Post
Looks good!
What foam do you use for the monobloc?
Dow Blue or Owens Corning Pink work well. Whatever I can get my hands on. Sometimes scraps from building sites are the best source for "free" material. Otherwise The Home Depot or Lowes.

Ken
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Old Dec 02, 2012, 03:36 AM
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Canada, BC, Williams Lake
Joined Jan 2010
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Ken you and mike are way to modest .


Springer(Mike) and dz1fsb(ken) are 2 of 3 partners that sell MPF foam which is Modelplanefoam.com . Its an amazing product at a great price . Its made in the US . It might be more then you need for your first build but once the bug get a good hold on you buy some .... you'll be glad you did
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Old Dec 02, 2012, 07:43 AM
treefinder
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Joined Oct 2004
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Don'tcha just love satisfied customers? Thanks Chris!

Just an aside, my grandson's Christmas present is gonna be an MPF built 33" BB. (now I'm committed!)
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Old Dec 02, 2012, 10:28 AM
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What size blue baby would you work?

hello, I am new to the hobby and I have a 2 brushed motors (380 and 390) and ECSs from a sky fly 2 and wing dragon with a 8.4v 1600mah and 7.2v 1000mav batteries. Would it be possible to make a flyable blue baby out of these left over parts, if so what would the 33 or the 42 work best?
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Old Dec 02, 2012, 10:31 AM
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United States, NC, Mooresville
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Quote:
Originally Posted by Wilfor View Post
Ken you and mike are way to modest .


Springer(Mike) and dz1fsb(ken) are 2 of 3 partners that sell MPF foam which is Modelplanefoam.com . Its an amazing product at a great price . Its made in the US . It might be more then you need for your first build but once the bug get a good hold on you buy some .... you'll be glad you did
Thanks for the hint
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Old Dec 02, 2012, 11:16 AM
Slipping the Surly Bonds
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Attica, MI
Joined Dec 2006
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Of course another option for a monobloc is to laminate the FFF or MPF or Depron. Whatever you use. I did this for many Oshkosh Specials before going to an engineered structure. While the latter is more time consuming it has made for a more robust structure. Check it out on the Blu-Baby Classic 33 thread. Free plans and how-to there.

Ken
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Old Dec 02, 2012, 03:21 PM
In Rc for a LONG TIME FFAA#1
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Canada, ON, Ottawa
Joined Jun 2004
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Quote:
Originally Posted by mattsdaug View Post
hello, I am new to the hobby and I have a 2 brushed motors (380 and 390) and ECSs from a sky fly 2 and wing dragon with a 8.4v 1600mah and 7.2v 1000mav batteries. Would it be possible to make a flyable blue baby out of these left over parts, if so what would the 33 or the 42 work best?
gear drive or direct drive?
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Old Dec 03, 2012, 06:51 AM
Geezer
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Central Kentucky
Joined Oct 2006
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Quote:
Originally Posted by mattsdaug View Post
hello, I am new to the hobby and I have a 2 brushed motors (380 and 390) and ECSs from a sky fly 2 and wing dragon with a 8.4v 1600mah and 7.2v 1000mav batteries. Would it be possible to make a flyable blue baby out of these left over parts, if so what would the 33 or the 42 work best?
Quote:
Originally Posted by laserman View Post
gear drive or direct drive?
IIRC, the Sky Fly 2 and WD had a 42" wing span with a direct drive 380 and had Nimh batteries. The 42" Blue Baby might be better than the 33.
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