Firewall

[Cedric R 2]

Hello,

Would anyone had Kitfox firewall drawing?

I have to build one, and it would be great if I could start from something existing

I understand design has changed during the years.

This design being on the earlier Kit:

And that one on actual Kit:

And this one being my Kit

I like the idea of folding only one sheet of metal, even if it must be cut in the middle afterwards. 

I also understand the newer Kit has room for a flat surface under the rudders, what we don´t have on earlier models. 

Thanks for your suggestions, Cedric

Edited 12 May by Cedric R

[1avidflyer 2033]

The sides and bottom just follow the fuselage, and the rounded top has to fit the cowl.  With my firewall, I had to recess the center area, because I was using a Jabiru engine, and that is where the carb sits.  The bend forward is right at the cross tube that goes full width of the fuselage.  It gives room for the rudder pedals and master cylinders.  The motor mount determines it's angle and distance forward.  Kitfox sent a bunch of pieces that you were supposed to rivet together, not sure there was an actual drawing.  JImChuk 

[Cedric R 2]

Thanks Jim

[AvidJack 33]

I had to redo my firewall after receiving the exhaust for my 912.  I'd guesstimated the need for pedal clearance, and while I had plenty of clearance on that side, the exhaust didn't fit..  IF I remember correctly, the top of the pocket ended up being 3.5 inches,  It'll be a couple of days before I can get out to measure.  Bottom went straight to the floorboard, then folded under to add a bit of protection under the footwell.

Mine's a 1992 skystar speedster kit, 1200 gross, with incomplete manuals.  The plans for the firewall in that era were all over the place.  I very carefully followed the instructions in my original (partial) manual as I fabricated the first iteration of the firewall, and.. discovered that those instructions were for a different 912 CDI setup, moving it into the cabin. Third time's the charm?  Picture is of the first iteration, including that *(& window, which was to be hinged.

I'm looking at the floorboard for your kit, it appears to be stopped short of the firewall?  Here's mine (the outer edges had to be trimmed later to fit the cowl.  That might be where you could get a bit more depth? 

[Cedric R 2]

Thanks Jack, 

What you´ve done is what I have in mind, although I believe it could be done from one piece of metal.

The floorboard is custom made, I just bought a piece of plywood and cut it to my needs. 

I can also see that you bought new brake cylinders, where did you get these from? I got 3 cylinders from previous owner, but they have different length.

As you can see on the picture, the one in the back fits where it should go, while the one in the front (right rudder) is right now attached to the return spring. 

[1avidflyer 2033]

Those are Matco brake cylinders.  JImChuk

Master Cylinders Archives - Matco Aircraft Landing Systems

Edited 16 May by 1avidflyer

[AvidJack 33]

As Jim pointed out, they're matco.  They came along with the rest of the partial kit.. and if I recall, they're the matco mc1, the old master with the built-in reservoir. While the plumbing is easier, I'll probably end up replacing them with one of the newer models with a remote reseervoir down the line- it's easier to do a quick fluid check if you have a glass reservoir, or even visibility of the line going to the cyinders.

I made my firewall out of galvanized material- scrap HVAC plenum material.  Those creases add a bit of rigidity, and cut down on transferred vibration (noise). Not sure of your desire to make it all out of one piece, but you may have a larger brake available than I have. Without the actual dimensions (still haven't made it out to check on that top ledge length, which would pretty much define the shape and angle) it took more than one try. Drilling out the (SS) rivets was easier than scrounging another plenum.  I didn't want the hassle of the firewall blanket on the engine side, so went with a 1/4" carbon felt welding blanket on the cabin side before installation. That, too, should cut down on noise, and provide heat insulation and protection.  Plus, I like the way it looks :-).

 

[AvidJack 33]

My original floorboard picture had an installation of the old matco MC2 (I think) slave brake cylinders, no reservoir.  The firewall picture shows the MC1 I later switched to.  In looking at your brake setup, I noticed that the installation has changed- those tabs make more sense than fabricating the hinge blocks to accept the brakes.  But it might change the width of the pocket a bit, since the cylinder is now on the central side of the pedal?  The one cylinder you have attached looks like a matco- maybe another to match?  It does have the built-in reservoir, so whatever it is, it looks as though you're halfway there.

[AvidJack 33]

And...  in your picture, unless I'm mistaken, the one in the front (right rudder) is attached in the correct place to give a longer (and stronger) stroke. The original brakes (mine) had two flaws- not enough leverage, and the piston size in the old (discontinued) matcos was enlarged to give more volume.  The rudder return spring (in my plans) fits onto the same place as the rudder cable- you can catch it in the lower right of this picture. Only one per side.  Jim might have insights into those brake pedals- He's seen a lot more than I have, but I'm guessing they're more like the avid redesign?

$.02

[1avidflyer 2033]

I would differ on which brake pedal/master cylinder is correct.  I think the back pedal is correct.  There is much better leverage for added pressure in the brake lines with the shorter, lower tab.  Actually, looking at the weld on the closer "return spring tab"??  I think those tabs have been added by someone after they left the factory.   I don't recall ever seeing brake pedals with two tabs on them.  And that is not where the return spring is meant to be attached to.  Jack's last picture with the return spring attached where the rudder cable goes is how I've seen all of those I've dealt with.  Think about it, when you would push down on one rudder pedal, the other pedal is pulled back.  That would cause the brake to be applied somewhat from the spring pressure.  JImChuk

PS  here is a picture of my Avid rudder return spring, the Kitfox is pretty much the same.

Edited 16 May by 1avidflyer

[AvidJack 33]

Finally made it out to the hangar.  That upper ledge on my firewall ended up being 3.25 inches, to accomodate as much room as possible for the exhaust on the 912.  Pic of the 3rd iteration of the firewall attached.  Note the angle iron on the outer edges- those provide reinforcement and stiffening for the rudder return springs located on the other side.  You may not need as tight a ledge if you're going with the 582.  I'm still trying to figure plumbing routes.

I had to make my floorboards as well, as mine didn't seem to be included.  I later found them on the bottom of the big flat box containing sheet metal and such, under cardboard. Old projects can be full of their own mysteries.  When I picked up the catalina, the guy selling it swore that that long chunk of formed wood (banister railing) was part of the project.  Jack