Filling and sanding the cowling some more

Tonight I spent about an hour sanding down the filling of bondo and in some more severe areas the microfibers and epoxy. The expoxy takes some time to sand but really comes out well once all the hard work is put in. I sanded until it seemed unreasonable to continue then I added somemore bondo to continue filling it takes a few layers of bondo and Sando before it it nice and smooth. I then will fill it with a couple of coats of filling primer to finish it off ready for paint.

Time spent 1 hour total time spent 26 hours.

Filling and Sanding the Cowling Patch

Today I spent some time using micro fibers and epoxy filling some of the bigger holes in the cowling patch I also used some Bondo to fill the pin holes and to help level some of the not so smooth surface. The extra layers of glass on the inside came out well and really stiffened up the patch a whole lot.

Time spent 1 hour total time spent 25 hours

Annular Cowling Fix continued

Today I was able to inspect my handing work in the morning since I brought the cowling home to let the epoxy cure in the 68 deg house rather then the 30 deg hangar. It turned out pretty darn good, but the truth will be found out as soon as paint get on there. So after work I stopped by the house on the way to the airport to pickup the cowling. I got it to the airport and started in on cutting the inside out with an angle grinder cutting wheel. I got the first two pieces out and started getting the clay out of there. I then carefully continued cutting the inside back to the edge to get all the clay out. I did all that and then sanded the inside to get all the clay out. As a final cleaning I used acetone on a rag and wiped the inside out. All said and done it was basically free of clay like it was never there. I then sanded the out side of the new patch and it seems to smooth out all right but will need some filler for the pin holes. I fit it back to the airplane and was shocked how well it fit to the fire wall now that nothing is blocking it and there plenty of room. I took the cowling back home again and laid two more layer in the inside for more support.

Time spent 2.5 hours total time spent on the mod 24 hours.

Annular cowling the fix

Well I was so pissed off about the cowling and frustrated that I didn’t go to the airport yesterday and gave myself a day to figure out what to do about the cowling.  It seems that my airplane is either off by a 1/4″ or the cowling is not quite right.  Either could be true and the airplane isn’t going to change very easily and so far I can’t find out where the engine is on wrong or the fire wall isn’t right or what. I do know Kevin Kimball has stated that an aircraft built to 1/4″ is as good as another problem is the cowling just doesn’t leave room for 1/4″ of issues.  I knew at this juncture if I wanted the cowling on the plane I would have to do a little surgery.  I was really trying to avoid any surgery since the cowling has a very nice finish of gel coat but it just had to be done.  I stewed over how to do this all day Sunday and finally came up with a solution this morning.   I decided to use modeling clay to build out the bulge of the cowling and match the profile the best I could.   Tonight I did just that.  I used some poster board and taped it to my fuselage to transfer mark the cylinder heads exact location on the outside of the cowling so I could start with the clay.  I then started laying the clay and shaping it to match the contours the original bulge for the cylinders.  I bulged it out about 3/8″ which will give me about 3/8″ or maybe a bit more room between the cylinder heads and the cowling so that will match the other side.  It’s not the best solutions but it is the best solution with still keeping the cowling.  I finished the clay and then used my angle grinder and removed about a 1″ wide strip of gel coat passed the clay for the fiberglass to adhere to.  I got everything done and two layers of 9 oz cloth laid tonight.  Tomorrow I will cut the inside out and remove all the clay and lay to more layers of cloth on the inside for more structure if necessary.  We will see.  Below are some pictures.

Time Spent 3.5 hours total time spent 21.5 hours.

Annular Cowling

Today I was determined to figure out where and why the cowling was fouling on #2 and #4 cylinder.  Basically the left side of the engine doesn’t quite fit.  The cowling is very tight already and the right side has about 3/8″ clearance from the cowling the left side is zero.  I spent about 3 hours trying to measure and figure out a way to make it not foul but left the airport very frustrated.

Time spent today 3 hours. Total time spent on the mod 18 hours.

Annular Cowling

Today I spent the better part of 3 hours finishing the drilling on the bottom piano hinge and trimming the cowling some more for a slightly better fit on the aircraft. I have removed and reinstalled the cowling probably 30 times now. I am never satisfied with the fit until it is perfect. Right now I am battling the left side of the engine rocker covers are hitting the cowling a bit. Below are a few pictures after I decided to wheel the plane out of the hangar for some overall shots.

Time spent 3 hours total time spent on the mod 15 hours

Annular Cowling Piano Hinges

I spent the some time after work working on the cowling since my order from Spruce came in last night.  I received my piano hinge for joining the two cowling halves.  I chose to spend the extra money on the extruded piano hinge which is a fair bit stronger then the rolled piano hinge.  I marked out 1 inch on either side of the joint.  and then marked out the rivet line.  I plane on using countersunk 1/8″ rivets to attach the piano hinge.   I marked both sides out and used 1 inch spacing for the rivets.  I drilled out the top side using packing tape to hold both halves together.  Below are some photos.

Time Spent 2.5 hours total time spent 12.0 hours

Exhaust Modifying Continued

Today I went to Lowes Aircraft Supply to buy the 1.5″ schedule 4o PVC and all the angles.  I bought 30 bucks worth of fittings and pipe.  I know I don’t need all those so I just save the receipt and take them back.  I got to the hangar and spent an hour hangar flying since 4 of the 6 Pitts owners were around and we were discussing the finer points of the IAC and other things.  Long story short I got to the hangar and routed the the new pipes checked fit with the cowling installed and all looks good.  Below are some pictures. I have an order from Spruce coming tomorrow with the Piano hinge and loads of other hardware needed for this mod.

Time spent today 3 hours total time spent on the mod 9.5 hours

Modifying the Exhaust

I have been stressing the the changes that will be required to tuck the exhaust into the cowling. I spoke to Aircraft Exhaust www.aircraftexhaust.net owner Rich Lopez about the changes.   He told me he could send me some adapters to the exhaust.  He told me I could cut up my current exhaust and then just use the adapters to change from my exhaust to PVC mock up again.  So basically I would be back to square one on the exhaust.  I got home tonight and started looking at some of my exhaust pictures and after about hour of looking at the photos I came up with a hair brained Idea.  I thought about flipping the collector up so that the pipes that were on top were now on the bottom and the top pipes would have to be re-done but that is better then re-building 4 pipes.  I got off work the next day and went down to the hangar to test my idea.  It turns out it will be nearly perfect.  The added space from the gear mod and the change in oil sumps from when I built the first exhaust  gave me the perfect amount of room to route the forward cylinder pipes on top of the aft cylinder pipes and now the collector is sucked up to the fire wall nice and close and the whole exhaust system will be inside the cowling.  Tomorrow I will go get some more 1.5″ schedule 40 PVC and loads of fittings.

Time spent 30 minutes total time spent on the mod 6.5 hours

Fitting the Annular Cowling

Today I set off to get the cowling fitted as close as possible so that I could figure out how much my exhaust has to be modified.  I cut some notches out of the bottom of the cowling so it could fit around the landing gear legs.  I had to remove the oil cooler and the #1 and #2 engine cylinder baffles which will have to be modified.  I also removed the #1cylinder forward baffle which will be replaced with a full front baffle.  This allowed the cowling to fit a little bit better.  I then used a zip tie on the rear top vents to hold the top together and I used Packing tape to hold the top front and the whole bottom seam together while I measured to see where the cowling sits.  I also used a ratchet strap on the firewall end to help pull down the cowling.   Then I got a profile made of the bottom of the cowling using poster board.  I then pulled the cowling off and temp installed the exhaust.  I used the poster board and found out that I have to pretty radically change my exhaust routing.  I will have to call Aircraft Exhaust and see what they can do.  Below are some pictures that might help explain all of this.

Time Spent today 4 hours total time spent on the mod 6 hours