Build Log 70.5" wingspan 1/22 scale XF/XR-12 Rainbow

[CapMike]

I am going to let the cat out of the bag a little early for everyone's pleasure. I have been working on a new design completely drawn by myself and coached by Zeke from Park Scale Models. As you may lnow I like doing things others have not done and would like to see in the model industry. With a little pushing from GLewis I began drawing the plans for an XF/XR-12 Rainbow. 120 hours later I had something good enough for Zeke to burn with his Laser. Now by all means I am not finished with the file due to some design changes needed. I am working on the prototype currently and hope to have it finished within the next two and a half weeks. My intentions for this plane was to make something easy to build wth gentle flight characteristics. Do not know about flight yet, but she sure goes together quick. My cut parts arrived on Monday the 11th and that night I had the complete fusalage assembled as well as the Vert stab. Stupid me forgot to put enough horizontal parts onto the cut file so I had to make up a sheet for a cut file. Zeke did not have time to cut them so I hand cut them today. I now need to finish building the Stbd wing and then begins the fun of sheeting the entire fuselage. I had been debateing how to control the elevators as well as the rudder, when it dawned on me that there is enough room for servo placement right inside each respective part. I am useing the digital servoless retracts from RC warbirds and they are a very nice unit with scale operation. Yeah 6 ounces, but on a bird this big I dont see a problem with that weight. If I were to use robarts oleo struts and 3 servos I would be at or above that weight and still need something to slow the speed down. For power I am useing 4 Dynam 2208-17 motors swing 7x7x4 props and 2100 3s lopo's. I am useing a ubec to power the reciever and probably going with a sperate 800mah 2s pack. I hope to have her flight ready for Zeke to do the Maiden at NEAT in three weeks. so how about it guys chime in and tell me your thoughts. Kits? possiably if there is enough interest and demand. The only way she will be offered is in a short form. No I will not post drawings of the parts nor will I sell them. I have way too much time into this already. Ok here are some pictures to get you going while I start building the last wing.

[Ascolta]

Very nice Mike, this a beautiful flying machine!!! Keep up the fine work.

Dale

[CapMike]

Thanks Dale. I am finishing the 'Bones" today. I just have a few more parts to cut and the wings will be complete. Then it is on to the electrical parts before I can sheet and cover the plane. She is looking very big setting there on the floor with the horizontals on her and one wing. I will post pics of the bones tonight, and then tomorrow it will be sorting out the electrical system. Then the fun of planking and sheetig will begin. I plan to make the wings removable. Hmm should have thought about that for the rear assembly as well.

[Akentut]

Nice so far Mike. I see you've put your self into overdrive for one being finished in under 3 weeks.

How about a photo of the real one you are working from? Never mind, I found one. xr12

Alan

[CapMike]

Here are a few pictures I have been working from trying to keep as close as possiable to the true aircraft.

[CapMike]

Originally Posted by Akentut

Nice so far Mike. I see you've put your self into overdrive for one being finished in under 3 weeks.

How about a photo of the real one you are working from? Never mind, I found one. xr12

Alan

Alan; I am actually not putting myself into overdrive here. This design is so darn easy to assemble I think a 12 year old could do it and come up with a reasonable looking plane as well. The big nagging question though is will it fly ?? I think the time I spent in CAD trying to make it an easy build was werr worth it. Each wing assembly took a total of about 45 minuted to complete. Not bad for a first time design, and with the coaching of Zeke and Glenn I think it has progressed very well. as soon as I find the memory card for my camera I will snap a shot of the bones. Total build time so far. about 12 hours. Now comes the hard part. Electronics and sheeting/planking. Especially the tail cone, but I am up to the task.

[Geoffinpdx]

The Rainbow is indeed a gorgeous plane. What scale is it?

Geoff

[Thomas B]

There is absolutely no doubt that it will fly if properly built and set up....my micro one flies very nicely.... So stop worrying about THAT!

The proportions and lines of this aircraft are such that it is a given that it will fly.

I have been dabbling a bit at one a bit over 77", at 1/20 scale. I am going with a glass fuse, vac formed nacelles, balsa covered foam wing and balsa tail group. Glad to hear that you are planking yours. I also prefer the look of smooth skin on large all metal aircraft like this one.

The little foam XF-12 is alive and well and going strong and flew at SMALL this past June.

[Thomas B]

Originally Posted by Geoffinpdx

The Rainbow is indeed a gorgeous plane. What scale is it?

Geoff

With a full scale wingspan of 129 feet 2", his is right at 1/22 scale.

[CapMike]

Originally Posted by Geoffinpdx

The Rainbow is indeed a gorgeous plane. What scale is it?

Geoff

Geoff she is a 1/22 scale I think any bigger than that and would need gasser motors for her. ok onward and as promised I have taken pictures of her BONES. there are a few tweaks I need to do as well as hand cut the #6 former and then stringer her up. then comes the joys of planking. By the way this is only the prototype build to confirm everything will work before I build the final version for release. At her present state she weighs in at a tidy sum of 6.7 ounces I may even be able to keep her under the target weight of 39oz. We shall see once everything is completed. Tomorrow electronics and doing the fuse strngers. Woo Hoo I get to play with retract placement and actuation as well. Now if only my UBEC was here.

[Thomas B]

Originally Posted by CapMike

Geoff she is a 1/22 scale I think any bigger than that and would need gasser motors for her.
......

No way would you need gas for a larger model.... You could do nearly any size as an electric. A 1/10 scale with a span of 12.9 feet would fly great on 4 Axi 4130 or equivalent clone motors. Heck, it would fly on 4120 equivalents.

At your likely completed weight, all you will need is parkflyer type power for the 1/22 scale model

[Geoffinpdx]

Originally Posted by CapMike

Geoff she is a 1/22 scale

Park flier size! Given the lightweight structure thus far, and given that Ivan Pettigrew's 120" models fly on old 480 brushed motors, I can't imagine your needing anything but e-power for one twice the size.

[CapMike]

Originally Posted by Thomas B

No way would you need gas for a larger model.... You could do nearly any size as an electric. A 1/10 scale with a span of 12.9 feet would fly great on 4 Axi 4130 or equivalent clone motors. Heck, it would fly on 4120 equivalents.

At your likely completed weight, all you will need is parkflyer type power for the 1/22 scale model

Tom funny you should say that because I decided to use some Grayson Hobbies disposable foamy park flyer brushless motors on 2000 mah 3s lipos.

[CapMike]

Ok dumb tech question, but I am at that point now and want to make sure I get it right. The Ailerons are a whopping 14" long. I am undecided as to the placement of the control horn for them. If I go at the end inboard then I think I may get some torque issues. I was thinking of controling them from midpoint so as to make sure they work the same as well as knowing that the full authority will be exerted. Should I be concerned with this .
I do have this to say and am glad I bought it. Sure makes things easy and accurate. I am talking about a slot machine. Just mark out your hinge location, make sure you are straight and press the trigger. fast and accurate and no sweat. Ok off to make the other aileron and mount the LG. then sheeting of the wing. Pics will be posted later.

[Airboatflyingshp]

This is one very slippy airframe.... geared 480s will make it move beyond scale.... brushless will make it potentially ballistic.