About this Plan
Ajax - Rubber duration model. This is the Ajax MkII version from Keil Kraft, designed by Albert E Hatfull (the original Louis Heath MkI design was 1939).
Update 14/05/2014: Replaced this plan with a clearer copy, thanks to rchopper56.
Update 28/01/2019: Added printwood scan, thanks to NicholasTucker.
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User commentsHi Steve, This is an Ajax from Keil Kraft I covered with Solarfilm transparent cover [see more pics 003].
Ehsan - 04/09/2014
Hi Steve, I am building the Ajax and am installing a BR1103 electric motor. I ran into problems building the wing in 3 sections as per the plan. Building the wing in this way the 3 seperate sections do not line up. To get round this, I printed the port wing and then printed a reversed port wing, so the two outer wing section matched up. I then laid the two outer sections on the building board with a blank piece of paper between them and drew the centre section with a pencil and ruler. This has worked OK with the finished wing balancing on the centre rib. When I put the wing on the fuselage the wing rocks from side to side as it balances on the wing centre rib, but has no support where it contacts the fuselage sides. I suppose infill under the LE above the cabin wind screen would cure the problem, but I added a 'stub' spar on the deepest section of the wing running through the centre rib and two adjacent ribs.. I hope to have her finished by next week and will send some pics.
MalcolmJ - 24/08/2017
Hello, here are 3 photos of my KK Ajax converted to run on a BR1103 motor, with 400 ma 7.4v battery [more pics 004-006]. As explained previously, when I built the wings from the plan originally, none of the 3 wing sections matched up, so I re did the wing plan by using the port wing and then inverting it on the printer for use as a mirror image on the stbd wing, and then drew a new centre section to build the whole wing in one piece. As you will see in the photos I added two ribs in the ctr section to take the load of the elastic bands holding the wing on, and changed the LE to bamboo to stop the bands crushing the LE. I am not sure if I am going bonkers with old age but the wing centre section seemed incredibly weak to be held on to the fuselage with rubber bands. I ended up adding the 2 extra ribs to transfer the load on to the fuselage longerons, as well as a stub spar at the ribs deepest section to take the load of the unsupported tissue covering. What I cannot understand is that, as the plan has been around since 1939 and flown very successfully, why have I had so much trouble with the balsa being crushed by the mounting bands?? Anyone got any ideas? Any way the wing looks OK for a test fly this coming Sunday morning, 10th September 2017. Fingers crossed. I'll let you know how it goes, and hope the CG is in the right place.
MalcolmJ - 08/09/2017
This is the plane that started me off on a life long love of aviation, model building and flying. Got the kit as a Christmas present back in 1960 but never could get it to fly. It was always on the verge though. I'm tempted to have another go at it now, using these plans, 55 years later. Great site, brings back so many memories when I wander through it.
SteveC - 04/04/2018
No wing rib template (or am I blind?)
RD - 06/09/2018
Re: KK Ajax 1368 printwood [suppl. file]. Hope they will help builders of this old classic. The wing ribs are 'die cut' so not very clear.
NicholasTucker - 30/01/2019
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