About this Plan
VK Navajo RC. Radio control trainer model. Wingspan 64in, wing area 675 sqin, for .40-.61 engines.
Quote: "Hi Steve, attached are the 2 plan sheets from the 1967 kit from VK (Vernon Krehbiel), the 'Navajo'. I was given these plans around 1982 (I'm in Australia) and have just built the model. I had them copied yesterday after much procrastination. The originals were in very poor condition, yellow and torn, but the copier did a very good job. I can only see one place where there has been some page warping, and fortunately it is not a critical area. As far as I know there are no other plans of of this model in existence; at least not on the web. Which is a shame because it's an interesting and somewhat unique trainer model when they are usually so dull. Here's hoping the model will be resurrected. Having said that, there is currently a good Navajo build discussion going on at: http://www.rcgroups.com/forums/showt... Cheers,"
Update 25/05/2018: Replaced this plan with a clearer copy, thanks to theshadow. This is now beautifully restored and outstanding quality at 600 dpi.
Direct submission to Outerzone.
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User commentsColour pic of his nicely completed Navajo is by PhilU and found at the above thread address.
SteveWMD - 28/02/2013
Glad you posted the Navajo. I built one in 1968, it had an Enya .60 and an Orbit 6-12 with enormous PS2D servos! This model is excellent. It is more an advance trainer like the Goldberg Falcon and it flies like a dream but definitively not a primary trainer. I got the full size plans some time ago... Anyway, there is a catch. The original Navajo specifications states that the wing has a 'progressive airfoil' This means that the ribs from R5 to R10 have a different airfoil EACH rib. I remember this perfectly when I built the kit and I just don't know how to get the proper shape of these mentioned ribs. I thought this might be an important issue for those wishing to build this fantastic model.
Edubarca - 28/02/2013
In regard to the airfoil as per the previous comment, yes these are missing from the plans from R5 to R10. If you look at the plans closely you will see faint pen lines inside the rib section diagram at R2. I drew this shape many years ago to determine the R10 section, which was based on the required chord of R10, and the wing tip section diagram which gives the required thickness. The remaining ribs I merely tapered back to R4. Of course these days somebody with CAD software could do the design properly for each rib. It may not be exactly true to the original, but we can't do much better unless somebody with a remaining kit traces the actual rib outlines. I'll look into this. The other issue was how much of the total taper was supposed to be on the top or bottom. I took the easy option and kept the bottom of the wing flat.
Phil U - 28/02/2013
The final word on the rib sections. I can't get hold of any section diagrams for R5 to R10. However I can confirm that the main spar is not tapered, either top or bottom, and rib shape is consistent throughout the wing. The R10 rib thickness is the same as R4 at the main spar, therefore the leading edge has the same profile all the way through the wing. The only difference is in the chord length as the ribs taper from R5 to R10, so it's a simple matter of interpolating the rib section back to the trailing edge from the spar. The top and bottom trailing edge sheets will have no vertical warping in them if the job is done properly. Apart from this the plans are complete.
Phil U - 06/03/2013
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