KF IV Cowling

[Brent Allan]

I am a noob on this forum with a KF IV project with 100hp Hirth 3703 installed. A cowl was built and it is time to figure out how to mount it. A 5-blade Kiev Prop will be utilized on this bird.
Any one used the cam-loc vibration isolated mounts? http://milspecproducts.com/cowlmt.htm
I am considering the piano hinge install as an alternative.

Anybody have a few detailed pics of how they mounted their cowling?

This Forum looks to be the right place to look for building tips.
Brent

[cap01]

Hello Brent , welcome . I'm sure others have but I've never seen or heard of your engine prop combo . as for the vibration isolator cam-locs , the model IV uses the regular cam-loc without the isolator . Vibration is not a big problem with the rotax . If it shakes , you have a problem . I don't have access to my pics right now but if no one else comes up with any I'll see if I can find some .
Have fun with the project

[HighWing]

Brent,
I agree that the vibration isolator camlocs would probably just add a bit of expense with no real benefit. Regarding the camlocs and piano hinge. I have done both. My first Model IV had the camlocs throughout, but my present project has the piano hinges between top and bottom main cowl. I also did it on a Lancair IV I worked on - that was the thought came from. My experience tells me that the piano hinge requires a bit more finesse with regard to firewall trim. Mine is still a bit of a chore to push the hinge pins in, but like most things, I suspect this will change with a little flight. As I recall, everything on my first airplane was tight, then tended to normalize with use.

My hinge pins are inserted from the door side of the cowl and I added some guides made of thin 4130 steel that the pin is inserted through that secure the pin which holds the cowl tight against the door post. Picture of the passenger side guide attached. The pins have a 90° bend as a handle. I figured with the insertion in the cockpit, visual clues will prompt needed adjustment and they wouldn't need the elaborate securing devices to prevent them coming loose in flight.
Lowell

[Brent Allan]

I also worked on two Lancair IV's, both with hinge pined cowls! I like the hinge pin cowl cuz I have experience building them but is it worth the time on the "dirty" KF??? I now agree that those expensive comloc mounts are cool but expensive.
I figured to mount the cowling per the plans onto the three (on each side) tabs on the fuselage. I am thinking about how to support the bottom cowl better/properly than those six fasteners. Maybe across the bottom?? I just don't think those six mounts are strong enough????

[HighWing]

Brent,
A couple of thoughts. The camloc attachment design from the factory works. Legend tell us that there are between 3 and 4,000 Kitfoxes with that design and to my knowledge it has never been a subject of discussion.

The glass cowl at the mating line doesn't always like to lay flat. Sometimes there will be a scalloped effect where the camloc attaches being flat against the bottom cowl, then a little ballooning out between camlocs. To try to avoid that, on my first IV I made a joggle on the top cowl that very slightly overlapped the joggle on the bottom cowl. It worked fine, but probably took every bit the effort that a hinge installation would. Of course, I microed the joint both times to get it closer. If you made your cowl, you may have eliminated the ballooning tendency already. I made a ton of mods on my IV, and the vast majority were to clean it up as much as I could. Almost all were glass, but before the Lancair days. A note on clean - My first IV had lots of fairings with full airfoiled tail surfaces with gap seals on the horizontals and verticals. Once on a group flight to Idaho, the six of us stopped in Winnemucca, NV for fuel after a three hour first leg. We stayed together by flying at the speed of the slowest airplane. Whenever we stopped, the amount of fuel we each loaded was always of great interest. This time the fuel amounts went from a little over eleven gallons for the most thirsty airplane to my 7.3 gallons. This reflected the difference between fully faired and unfaired. They can be cleaned up a bit. Maybe not only for a little more speed.
Lowell

[Dorsal]

The six mounts on the bottom are plenty strong enough when the top cowl is attached.