RV-7 N117TR

[BillL]

I have seen some that just put a large diameter disc of semi rigid foam on the hub then let it float there. The internal pressure (I assumed) pushed it up to the disc of the cowl. Any motion was just sliding against the cowl. This way the seal to the hub was snug and did not have to absorb any misalignment or wiggle from start/stop. Like yours, my cowl is hard to get on, but I have developed a technique that might work. The disc design might allow easier cowl install/removal. I will send a picture when found again :roll eyes:

Keep it going Andy!

[crabandy]

Another interesting front seal design BillL! My current foam seal setup doesn't add any complexity to assembly/disassembly, the flap seal to ring gear underneath the weight ring would've complicated it.

I installed the wife's new dryer yesterday, after uninstalling it from the "free" setup and installation service.... Anyway I used some of the leftover tape from the second installation kit to protect the surface of my prop spacer. I initially used 1 piece making sure the tape joint wasn't being peeled off by the rotation. I ran the engine for a minute and checked the foam seal, just a little smoking. After a couple runs and checks the seal "conformed" to the spacer and no more smoke, you can slightly hear the seal rubbing when turning the prop by hand. There was foam dust everywhere, but a quick blowoff took are of it. Here's the prop spacer/tape/seal interface after 1 trip around the patch.



The seals were slightly trimmed down.



I peeled off the first layer of tape to check for excessive rubbing and to reapply the metal tape without wrinkles. Everything looked good and wiped up easily, I applied 3 pieces of tape this time mostly wrinkle free.



Initial flight tests show 5-10 degrees cooler on CHT's with oil temp the same as prior, although it's only the mid 80's not the mid 90's like several weeks ago. Both upper and lower cowling pressures seem to be up .75-1 inch H2O. Bumpy and clouds weren't cooperating but speeds seem the same. Enough time and fuel on testing, I'll continue to gather more data on upcoming trips.

[crabandy]

Even though the large Al-647 bottle does fit under the seat back with 1/4 inch clearance with the regulator I decided to mount it on the right forward side of the baggage area for easier access.



I wanted to tuck the bottle as far forward as possible for W&B as well as baggage space. This put the mounting hardware right in line with the flap weldment. Good news was the flap weldment had 5/8 inch clearance from the cover plate and a doubler/nutplates/bolt was just over 3/8 inch. The foam chunk and lines mimic the flap weld net movement.



With nutplates and doublers installed.



I used some thin cardboard to make a pattern for the upper mount/covey hole.



Long ago I dented this donor .032 wing skin with a dead blow hammer while dimpling.



I bent some 1/4 inch flanges for strength.





I made a doubler with flanges and lightening holes.



Bottle mounted securely.

[dsvajda]

Looks good, Andy. I mounted my O2 in the same place.

Dave
RV6
130 hrs and still learning how to land

[crabandy]

While I wait on an autopsy of my plane power alternator I figured I might as well do some more glass work.

I've been trying to play with different variations of re-shaping the lower cowling exit to get rid of the sharper corners. I installed a lower firewall bump/curve a while back in this thread http://www.vansairforce.com/communit...d.php?t=112941

My current outlet is about 50 sq inches, I'm anticipating more airflow through the new exit and aiming for a 10-15 sq inch reduction on the exit size. I'm visualizing an elliptical exit that has radiused corners glassed into the lower cowling feeding the exit snugged up against the lower firewall bump/radius. Kinda a combo of the kindergarten cardboard sculptures below.






Everything taped/waxed up and ready for some pour foam, my main goal was to get accurate placement of the lower firewall bump.

[crabandy]

Not sure the pour foam was a great choice, it took an hour to get the cowl off.



She looks pretty ugly at the moment, I used a large concrete cutoff wheel to cut grooves into the foam as a kind of sanding gauge to rough out the shape. I'm doing a lot more staring and thinking then I am sanding, I hope to have the final shape in a couple more days.

[crabandy]

A little more shaping tonight, using the 14 inch cutoff wheel to cut radius guide marks into the foam worked pretty well for shaping the lower cowl exit. Pretty easy to eyeball a center for the cut and then measure from the cut off wheel to the cowling to keep things concentric. Kinda odd that I actually had a 14 inch concrete cutoff wheel laying around the shop from a totally different project.



You can see parts of the guide marks cut into the foam, basically just sand the grooves to the same depth or gently sand the grooves flush and it shapes itself.





A paper towel roll is close to the same dimensions of the lower firewall bump/radius, trying to visualize how I want these curves to intersect.

[bret]

Looking good, funny, I used to use those beer box parts and same tape to visualize and make pattern stuff......too bad I don't drink beer anymore :-( now I go and steal all the wife's cardboard file folder supplies ;-)

[crabandy]

A couple pics of my lower cowling cooling exit....







2 layers of 8.9 oz glass and 1 layer of Lantor Soric, seams and edges all received a bead of Flox. If it works well I'm hoping to remove the foam/filler and reshape the aft 1/3 of the lower cowl.





For now I think I'll taper the outside of the cowl to match the new contour and see what happens.

[DanH]

Andy, remove all the pour-in-place foam. Been, there, done that. Over time pressure changes cause it to swell in some spots and crush in other others. I had some inside wingtips and had to take it out. Had a bit more in my cowl mod and had to vent that area of the core.