Dan & Cole's 1050 Build

[D&CJohnson]

Hello Team Kitfox.

My name is Dan. I am a previous model 3 owner, 20 years ago. I currently fly an antique biplane, but my family favors the idea of the kitfox side by side seating and enclosed cockpit. A friend started building a hangar out of shipping containers and that got me thinking about folding wing designs again. It turns out the fox won't fit, but the idea was already building steam. I thought I'd like to have the repairman's certificate so I'm willing to build even if it seems less expensive to buy a flying example. My son is 15 and has said he would like to participate in the build. That adds some motivation to move forward. With that I started keeping an eye out for a project.

I really loved the STOL performance of my K3/582 and really considered a nice model 3 project I saw advertised. I want to make this build my own and my focus was mainly on performance and utility. That was leading me down a path towards something Yamaha powered. After much consideration, I felt the 912iS was a good step up from the previous 582 but with reliability I could feel good about sitting family behind. No slam to the Yamaha guys, I'm jealous. I ended up purchasing an unfinished K4-1050 and a very low time 912iS.

The first couple of weeks with the project were going thru the manuals and trying to put the most recent revisions in place, stripping everything down to the bare fuselage, ordering some specialty parts I had decided on, making drawings to upsize the tail surfaces, and starting some small CAD projects while awaiting 4130 stock. Then the cutoff wheel came out.

My model 3 didn't have the elevator authority to 3 point with flaps down. I'm interested in low approach speeds and off field capabilities, so I have been researching what others have done to address this. In the end, I've decided to increase the chord of the rudder and elevator by 5 inches and adding an aero-balanced section above the vertical stabilizer. My wife and son preferred the stock shapes of the empennage, so you'll see the same curves preserved in the finished parts. We also had the speedster trim tab and are working that into the elevator.

The razorback mod is also imminent. In my photos you'll see the front side of the rudder and vertical stab reworked and the aft side of the rudder not yet changed. It gives a perspective of the change. I'll also reinforce the fuselage near the lift handle similar to what can be seen on Albert's build log (thanks). I've been giving some thought to reinforcing the strut carry-thru but may leave that alone as we shouldn't have trouble operating safely within the design limit.

Some other plans are TK main and tailwheel gear which so far has been my only sin regarding weight. After much debate, I am installing 8 inch Beringer wheels and brakes with aeroclassic 27.5 inch tires. The shocks and lift struts will be faired in Bowen Aero's carbon fairings. I am planning a single screen in the cockpit. I had planned to order a Grand Rapids efis during Oshkosh but have decided that will be put off until near the end of the project to see what new products may become available. I had some interest in Oratex, but I have a lot of polyfiber on hand and will probably be a repeat customer.

I'm interested in getting my son competent with basic drafting and have started introducing him to very simple CAD. We have drawn our floorboards and are having them cut currently. I am strongly considering making a new firewall from Titanium and this would be another good project for Cole to work with CAD.

I would expect this to be about the longest post you'll ever get from us, but now you have an idea what we have planned. It seems like a lot of folks have moved over to FB groups, but I felt like this would give a good record of our build and possibly some entertainment and info sharing for others. Be sure to let us know if you are interested in following along.

Best to you all, Dan and Cole.
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[avidflyer]

Well I for one have enjoyed reading your post. I think it is also really nice that you have your son involved in the build. That will make memories for sure. Stay busy at it, and you will eventually have a nice airplane that both you and your son will be proud of. Keep us informed as you progress on the build. JImChuk

[alexM]

Cool project. I wish I had the skills to cut and weld anything, let alone 4130 on something I would fly in.

What is a speedster trim tab? Does this aircraft have a fixed horizontal stabilizer with a tab on the elevator?

[D&CJohnson]

Cool project. I wish I had the skills to cut and weld anything, let alone 4130 on something I would fly in.

What is a speedster trim tab? Does this aircraft have a fixed horizontal stabilizer with a tab on the elevator?

It is just as you've described. The "Kit" for the tab includes a triangular profiled tab out of sheet metal, a Ray Allen servo kit, piano hinge, and birch airfoils to allow the area for the servo to be enclosed. I have another servo from a previous project and may use that on the rudder.

[D&CJohnson]

My friend Mark has been helping me modify the tail group on our project. We've made a lot of progress and are really down to finish welding and finishing up the brackets for trim tabs.

Today Mark asked me a question I've been pondering myself. Why is there no wire bracing on the kitfoxes' vertical stabilizer? I know the quick answer is, not needed, not in the design...but I can't help but notice that the vertical does flex and move fairly easily. I had the short rudder and have increased the height and chord of the rudder and added an aero-balanced section that moves above the vertical stab that would add additional loads although probably not much different than the larger surfaces on the 4-1200 and later. I may weld in a bushing in case I should feel the need to add bracing later. Has there been previous discussion on this? I do hope the razorback also may help support the vertical and rudder.

tail.jpg

[FoxbuilderWill]

My friend Mark has been helping me modify the tail group on our project. We've made a lot of progress and are really down to finish welding and finishing up the brackets for trim tabs.

Today Mark asked me a question I've been pondering myself. Why is there no wire bracing on the kitfoxes' vertical stabilizer?

tail.jpg

I suspect though I don't know for sure, that bracing wires would get in the way of folding the wings

[D&CJohnson]

I suspect though I don't know for sure, that bracing wires would get in the way of folding the wings

Good Point.
I hope everything feels a little more rigid with the braces installed and razorback added.

[Av8r_Sed]

Your rudder mods are looking like a solid improvement and well executed. Before you're done with the welding, maybe put some thought into the tailwheel & suspension you're going to use and possibly beef up the fuselage attach points. I've seen a number of nice rudders get crushed when a tailwheel spring lets go or some other bad thing happens in that area.

[Av8r3400]

Looks awesome!

[D&CJohnson]

Your rudder mods are looking like a solid improvement and well executed. Before you're done with the welding, maybe put some thought into the tailwheel & suspension you're going to use and possibly beef up the fuselage attach points. I've seen a number of nice rudders get crushed when a tailwheel spring lets go or some other bad thing happens in that area.

Thanks. I bought the TK main and tailwheel system, Beringer 8 inch wheels and Desser 26 inch tires. Everything is here except the wheels. I will research the forum as best I can but I am interested in any detail if metalwork is needed in the tailwheel mounting area. We are adding structure to the aft fuselage as outlined in Alberts build.

Thanks.
Dan