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RV-7 N117TR

So 870 or 780? I will order one or the other tomorrow.

Rats, it's the PMC780 dry. Email me Bill, I ordered extra and it has a shelf life so I might be able to hook you up.

Edit: Bill, I lied. I forgot about another project I had thought of to use the rubber on.
 
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Coming along nicely. :) I think you've got more hours in the cowling/plenum than some do in their entire planes!

I do work slowly :rolleyes: but I think it has more to do with the skimpy hours/week available to actually work on it. Like with the rest of the airplane learning the new skills take time, the next one will be so much nicer and go together much quicker! The couple of items that worked well on this project have been very rewarding.
 
It took a couple of trial runs to get the sequence correct. I roughed up the front edge of the trimmed intake duct and slid the reinforcement ring over the top. I poured the mold half full of urethane and brushed the boot with ure-bond adhesive. I positioned the boot into the mold and slid the reinforcement ring into the rubber and brushed on more ure-bond adhesive. I topped the mold off with rubber and put a little weight on top of the inlet duct to hold things in place, we'll see how it turns out.

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study, order, make, wait, refine, repeat

I do work slowly :rolleyes: but I think it has more to do with the skimpy hours/week available to actually work on it. Like with the rest of the airplane learning the new skills take time, the next one will be so much nicer and go together much quicker! The couple of items that worked well on this project have been very rewarding.

I am not sure with the research, shipping delays, and waiting for the micro to set hard enough to sand that full time attention saves any calendar time.

Outstanding progress, Andy! Then on to data acquisition. I will get the 780 dry for the wheel pant galoshes.
 
I am not sure with the research, shipping delays, and waiting for the micro to set hard enough to sand that full time attention saves any calendar time.

Outstanding progress, Andy! Then on to data acquisition. I will get the 780 dry for the wheel pant galoshes.

True!

I thought you might be making some custom couplers from the inlet rings to your diffusers, wheel pant galoshes are on my list somewhere....
 
True!

I thought you might be making some custom couplers from the inlet rings to your diffusers, wheel pant galoshes are on my list somewhere....

It's on the list, first is data and evaluation of the current design, then consider a change. I really like the idea, but Gotta Get Flying!
 
The rubber mostly cured overnight, I really like using the plastic HDPE material for molds because the rubber/epoxy peels right off

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I think DanH's aluminum ring insert is a better design, we'll see how the boot sticks to the inlet lip over time. It would be a slightly harder layup but I think I could make it a one piece layup next time. For now more progress, things seem to be fitting well.

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Hot Dog this is cool, lots of thoughts and pieces finally coming together. So far it's fitting to the baffle/plenum and cowling pretty good.

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I trimmed my lower aluminum clamp strip/curvy ramp to fit the inlet duct. I hope they work as good as they look.......of course beauty is in the eye of the beerholder. Although I'm aiming for "top of the line" I know realistically at best My work is probably just better than average, but I think I keep sliding that average up little by little.

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Wow Andy! You are doing some awesome work!

I think we need to submit your name for the annual "Dan Horton" award for professisonal fiberglass workmenship.

:D
 
Wow Andy! You are doing some awesome work!

I think we need to submit your name for the annual "Dan Horton" award for professisonal fiberglass workmenship.

:D

I appreciate the nomination, But my plane would look like chopped liver next to DanH's......well maybe ground chuck roast.:)
Meanwhile I'll keep learn'n and a build'n hopefully getting better with each project.
 
I made another "plug" to simulate the reinforcement ring of the inlet duct out of the same HDPE I've used for the rest of the project. I made the radius 1/16" larger than the inlet ring to give me some wiggle room, after I sanded things smooth it was probably more like 1/32 larger. Since the cowl split line doesn't bisect the center of the circle I also squared the sides of the HDPE plug tangential to the half circle (not sure how else to word it) so the top cowl can slide over the top of the inlet duct reinforcement rings.

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I paired the new HDPE plug up with one I previously made for the inlet rings bonded to the cowl. The center hole used by the circle jig in the router makes a handy centering pin.

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I was originally going to layup over the rubber ducts, but the diffuser shape was in the way to do a decent glass job. I clamped in the HDPE plugs and epoxy/floxed around the ring and glassed over the top.

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After some sanding the joggle is looking pretty good.

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The smidge larger depth worked out well, I had to do some sanding on the thickness to get things sliding in and out properly. I may shim my plug slightly wider for the next 3 joggles. The inlet ring/duct fits pretty well.

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Nice work, Andy - you are becoming a real glass master.

Thanks for the compliment Bill, but I feel like a slightly above average glass master. I think mastering fiberglass is a lot like mastering golf, my glasswork is much better than my golf game!
 
Nice work there. Are you and Dan the only ones doing this rubber factory stuff? pretty cool how those turned out. I like it.
 
I'm finally back at it, I made some clamping strips for the intake boots out of scrap. I planned on AN525 screws for the inside of the boot except for the top plenum to boot junction, it will have nutplates and threads sticking into the incoming air.

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My CHT's have been pretty balanced, but decided to do a little mod for the front of #2 just in case. I had already filed the casting slag from the fins but I also cut an extra .063 clearance and made a doubler plate in front of the zero fin depth area.

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Very basic bending skills to make an oversized blank renforcement doubler with a 2x4 with a filed radius corner and my river gun and flush set to match the bend on the existing baffling.

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If I would've thought this through before making the upper curved baffling it would e been 1 piece instead of 2. Oh well.

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I made he necessary holes to use adel clamps for my electronic ignition pickup wires to the baffling, by silicone seemed to work better.

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I taped up things to make a seal for the plenum. Ultra black stuck to the plenum and waxed tape on the baffling to leave a re-usable gasket.

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It left a good seal overall, slightly ugly but will be covered. I smeared both edges with Ultra Black but should've used a little bit more to make it wider and more consistent.

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I found my aluminum #7's and used a dead blow and a hydraulic jack for an anvil and beat them to fit the cowl.

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I dremel'ed and filed out the 7 cutout to fit.

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I'm glassing in a flange to hold the back of the 7 and secure the front outboard edges of the cowling.

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1 more trial fit of the intake boots before I seal them in place.

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There's probably an easier way to do this but I'll think of it after I do it the hard way. I used short sections of tubing as a compressible spacer behind the 7's, next step is to tape/wax parts I don't want to stick and fill the void with epoxy/micro and screw the 7's on flush.

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Here's the 7 screwed into position over a bed of epoxy/micro with a rivet set holding one corner in position. I'm also dressing up the horizontal edges of the cowling. So far I've found what works best for me on fixing the edges/lines in the glass is to fill the gaps with epoxy/micro and after it semi cures to run an old credit card down the gap once the epoxy mix reaches a "cold peanut butter" state and then sand off the excess with a block on the outside and needle file in the gap.

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I put an extra thick layer over the aluminum 7 because the epoxy/micro seemed to shrink in the gap as it dried.

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It took longer to find my sanding block than it did to sand off the excess, I was really surprised how well my aluminum 7's fit the cowling curvature.

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I used a needle file to cut in a paint gap to match the cowling split line between the 7 and the cowling.

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The recess is mostly done, I still have to split the cowl and remove the yellow tubing for the hinge pin. Too bad I forgot about taping a small section of the top cowling that is now stuck to the lower cowl, I'll figure that out tomorrow.

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Were you able to get it apart? I did this while doing the SJ inlet ring groves, luckily I went out to the garage during mid cure and had a panic attack, almost did not come apart :eek:
 
Were you able to get it apart? I did this while doing the SJ inlet ring groves, luckily I went out to the garage during mid cure and had a panic attack, almost did not come apart :eek:

Yup, no biggie with a putty knife and die grinder.
 
Lots of family things to keep me busy the last couple of weeks, some airplane progress was still made and I'll take what I can get. My oldest 2 wanted to help in the hangar, we had a productive 2 hours for all of us! My oldest stripped....I mean removed several hundred screws for me. Dad gave a few pointers etc on using the screw gun and she went to town, screws and bits are cheap for this kind of experience.

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My second oldest had fun sanding the excess filler off of my 7 hinge covers, cross hatching he curves. Amateurs teaching amateurs.

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I put 5 coats of epoxy on the cowl. I used to roll every layer but I think it was pulling epoxy out of some pinholes, this time I used just a credit card to squeegee all 5 layers and just rolled the last three with a cheap foam roller to smooth the surface.

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I sanded the cowling on the airplane, first with 100 (it's probably too aggressive and lead to opening up pinholes) than 180. I finished up with 220 with the cowling halves separated in the shop at home looking for shiny spots of epoxy under the fluorescent lights. I have a bad habit of trying to sand every shiny spot off and end up sanding back through the epoxy when the regular epoxy primer would easily fill the imperfections my hands/fingers can't feel. Thanks to a new RV neighbor who let me use his Awesome shop/paint booth I was able to prime the cowling yesterday. I'm happy with the basic shape and blending of the inlets on the cowling, but I opened up some pinholes in several spots. No biggie, after all it's more of a guide coat to see what needs more work.

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Prop is back on, just waiting on a torque double check tomorrow and safety wire. Interior portion of the annual inspection is 2/3 complete and going well, I can't say when but I'm getting closer.
 
The only thing I can think of when looking at your daughter is "Oh, the flexibility of youth". How much easier it would have been to build that RV9A if I could have got into positions like that. So wonderful she is a part of the project. Good for her and you. Future pilot for sure.
 
Yes, a much more flexible builder and pilot!

I sealed the intake boots with RTV, my sticky test showed Ultra Black doesn't stick the best to the rubber but I think it'll hold and come apart relatively easily. If it doesn't seal, weatherstrip adhesive sticks really well to the rubber but I'm not sure about withstanding the heat. My aluminum clamping strips on the inside of the boots seemed to work well.

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All sealed up (I hope) and ready to button up the last couple items on the annual and see how the round inlets/boot diffusers/plenum work together. I used some NAS1802-8/32 Phillips hex head screws on the plenum, I liked the option of drill driver or socket or a wrench for the hard to get to spots.

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Everything seems to fit pretty well and is ready for an engine run, I just have to put the inside of the airplane back together after the annual. I can't wait to wheel this thing out and clean the hangar out from the past 6 months of work.

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You can see the inlets are forward of the aft edge of the spinner, the Catto prop blades taper a lot and the inboard portion of the inlet has about 3/8" clearance. Even though the left inlet sticks out significantly more than the right side it doesn't stand out as far as I can tell. I'm still trying to view it from all angles to find anything that looks goofy.

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I'm just wrapping up the annual and it's time for some engine runs and see how the new boots/cowling work together. It fired right up and ran like it should. The first run was just in the idle/fast idle range for about a minute. After shutdown I had some smoke exiting the inlets and behind the spinner and once I opened it the oil door. It didn't smell like a fuel/oil/electrical smoke but I still got the cowl off in a hurry. I found a light dusting of pink foam dust on the components of the lower cowl, I think that along with dust/mouse milk on exhaust joints/LPS overspray was causing the light smoke.
Pie helping me with the first engine start, as you can see she's feeling like her old self with plenty of spunk.

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Good news is I was picking up 8 inches of water pressure in the upper plenum from the prop blast at 0knts and full power (966 AGL, Baro 29.94 and 94*F) , I'm still looking for my previous notes on the stock setup. Bad news is the right intake boot started de-laminating. While inspecting the boots after a full power run-up a little poking around caused the boot to separate from the front ring, The left side boot looks fine. If you recall I laid up the rubber boot first and then molded the front reinforcement ring onto the boot with some urethane adhesive, this is the joint that is coming apart. I did remove the right boot from the mold early (maybe 12 hours into 48 hour cure) so I could get the left boot in the mold, I'm wondering if the twisting/pulling it out of the mold before full cure attributed to it coming apart.

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More prodding and picking revealed the epoxy flox reinforcement ring underneath.

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I think I'm going to make a single piece layup on the right intake boot/reinforcement ring and see what happens.
 
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Looking Good, Andy!

Delam is a small setback - big news is your Pie is back - so glad to see that!

You have spirited plane, and a spirited child. They can be the most fun!
 
I had to remove 1/2 inch from the front of my plug to utilize it as a 1 piece layup, I added the center plastic from my previous mold to the cut-off plug.

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I re-faired it/epoxy coated it/sanded it/painted it, much easier and nicer the second time. I laid the fiberglass on the plug and trimmed it to shape.

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I didnt get any pics of the intake boot layup, much like before 3 layers of rubber followed by fabric impregnated with rubber and a final layer of rubber. I did not add any reinforcement to the front ring this time, it is just rubber. I did add an extra layer of fabric about 1.5 inches wide On the back of the inlet ring to the boot, I wouldn't add the extra fabric again as it was hard to get it to lay right and was bumpy.

As part of my annual I also addressed the slop in my tailwheel and tailwheel spring. I added taper pins to my tailwheel yoke but found I still had a little bit of slop in the tail wheel spring to bulkhead mount as well. I used a B&S #2 taper pin reamer and a AN386-2-14 taper pin, the taper pin was way longer than needed but figured I could cut off the excess. I made this "jig" from scrap wood to hold the tail wheel fork perpendicular to the longitudinal axis of the airplane, I figured a large square of 3/4" plywood on a flat hangar floor with a 2x6 and spacers of plywood at 90* wood (pun intended) do the trick.

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The jig worked well to hold the tail wheel yoke at the correct angle, but with the hole reamed to the correct depth for the taper pin left some hole slop to the left of the taper pin.

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Reaming out the slop in the top of the hole ended up using the entire length of the An386-2-14 taper pin with lots of length protruding up. I tapered the inside diameter of some stock to make a large washer until I can order an AN-386-3 taper pin. It sure is messy and oily in the back!

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The tail wheel is solid and straight now with no slop.

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Flying again!!

Another set of runups and de-cowlings made the first test flight a go! My goal was to incrementally increase speeds and record upper plenum pressures only, and not crash. I was astounded by my impossibly high upper plenum pressure readings but the airplane was performing normally with slightly cooler cylinder temps. I wasn't able to gather all the data I wanted due to lower clouds but still got in a .6 which was plenty for a first flight. After I realized I recorded pressures for the flight in mmHg they were much more believable converted to inches H2O. Looks like I picked up approximately 1.5 inches H2O across the speed ranges in the upper plenum and about 1 inch extra prop blast at 100 knts with the new cooling intakes.
I lost approximately 2 knots on the top only referencing my calibrated true airspeed. I was kinda expecting more speed loss actually, hopefully gain it back tweaking the exit next.
Oil temp seemed about 5-10 degrees hotter compared to the lower CHT's and topped out about 205 running full power, more investigation required.

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Post flight inspection of the intake boots and cowling was good, I noticed 1 small crack on the front of the plenum/intake boot joint.

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The intake boots are already showing some wrinkles....

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Looks like I picked up approximately 1.5 inches H2O across the speed ranges in the upper plenum and about 1 inch extra prop blast at 100 knts with the new cooling intakes.

That's about what I would expect.

I lost approximately 2 knots on the top only referencing my calibrated true airspeed. I was kinda expecting more speed loss actually, hopefully gain it back tweaking the exit next.

Again, to be expected. Higher upper plenum pressure with the same exit size means higher mass flow. Cooling drag = mass x velocity loss, so higher mass flow means more drag. Squeeze down the exit area to return mass flow to the previous level. Upper plenum pressure will rise again in response to exit throttling. The drop across the engine will remain the same, so exit velocity will increase.

Oil temp seemed about 5-10 degrees hotter compared to the lower CHT's and topped out about 205 running full power, more investigation required.

Unexpected. I don't know why.

Post flight inspection of the intake boots and cowling was good, I noticed 1 small crack on the front of the plenum/intake boot joint.

The higher plenum pressure loads the front corners. 1.5" H2O doesn't seem like a lot, but how many square inches in your plenum lid?

The intake boots are already showing some wrinkles....

Doesn't matter with a low Vi/Vo inlet. The boots are just sealing devices, not diffusers.
 
Great to see you back in the air, Andy. That crack looks like a stress concentration at the end of the stiffener below?

It might not be faster, but it sure looks faster.

Look forward to full test results, when you get a chance, of course.
 
Andy,
I was inside squeezing rivets when you went over. Nice motivator!! Could you fly over every time I'm in my shop?

Cheers!!

Fred
 
Great to see you back in the air, Andy. That crack looks like a stress concentration at the end of the stiffener below?

It might not be faster, but it sure looks faster.

Look forward to full test results, when you get a chance, of course.

Yes Bill, the crack does coincide to the aluminum clamping strip underneath. So far it hasn't grown, it's possible I just over tightened it.
I've spent enough time and fuel on pure test flights, I think I can gather the data I'm looking for on more purposeful flights......like on the way to Petit Jean for example.:)
 
More flights with G-Loading and aerobatics went well, so far the cowling/boots/plenum seem to be working well together. Perhaps I can leave the cowling on after a flight now.....

Not so fast, cowling and plenum back off for my first experience with a prop balance, you can see the sensors mounted on top of the engine. These are just my novice observations about the balance.

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It took a wider piece of reflective tape for the sensor to see the reflective tape on the back of the prop, thinking the steeper blade angle of the Catto might have something to do with it. The airplane has alsways felt really smooth, my initial IPS (inches per second) was .15. The 255 was the degrees from the reflective tape in the direction of prop rotation marking the heavy spot, so move 180 degrees from that spot and add a large -4 area washer to the ring gear support. I googled that most aircraft have initial IPS in the .4-.8 range prior to balancing, I also had to google IPS...

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2nd run showed the IPS lower and the degrees shifted slightly so we know we were adding weight to the right spot. If the degrees shift a lot the weight is too much or in the wrong spot. 4 runs total with another large washer and a small washer left an IPS of .01, time for one more run with a thin washer....or just leave well enough alone.

Thanks for the prop balance rdoerr01, she's smoother than ever!

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I decided to start sealing behind the spinner, pink foam cut out with a jig saw and epoxy/micro'ed onto the cowl. Im making the front hole behind the spinner smaller and adding a 90* flange with 1/2" clearance from the prop spacer. I'm thinking I can make the seal with 1/2 foam weatherstripping from the cowl flange to the prop spacer or some rubber baffle material from the cowl flange to the ring gear support.

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True-ing up the front hole with a 7 inch circle routed from a 2x10.

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I used a ring of baffle material with radial cuts to allow it to conform to the prop shaft. I wrapped stainless tape around the shaft for protection... Make sure you overlap the tape correctly by wrapping it in the same direction the prop turns.

Baffle material was attached with screws to the balsa/fiberglass closure on the cowl, similar to what you did.
 
Thanks for the advice Vern!

A couple layers of filler sanded smooth over the foam, then covered in wax with a scribed cardboard template to trim my glass to shape made things go pretty smoothly. I snipped "tabs" into the glass so it would lay over the 90* radiused flange. The new glass lays even with the front face of the cowl utilizing a small scarf joint. Looks like the wax toilet bowl seal I have in the hangar that I dip my screws into....

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Foam removed, sanded and 2 plys of glass on the inside of the flange behind the spinner.

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A fellow RV friend loaned me his ring gear/flywheel, Thanks again Ron! I taped it up and then taped the 7" blank on top of the ring gear.

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The tape lines will leave witness marks in the finished seal, but I think it will be function over beauty on this part. 3 coats of PMC780 Urethane followed by 3 layers of 8.9oz fabric impregnated urethane, I wanted it to be stiffer since the aft edge will be unsupported. My wife said it looked like an ugly birthday cake, I told her I was making her a top hat :D

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I finished filling/smoothing the new fiberglass and added a flange to the inside of the lower cowling.

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I popped the seal off the mold/flywheel, looks like it should work after some trimming and fitting.

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So I have an extra chunk of metal on my ring gear for W&B purposes. It interferes with the seal I made behind the spinner on the ring gear support and makes cowling installation and removal more trouble than it's worth. Pic of the "landoll" weight.

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I'm attempting plan B with a foam seal around the prop spacer, any advice please do tell. Foam seal on the cowl....

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Pics of the top & bottom cowl with foam seal installed, I'm still thinking about a metal tape over the spacer to absorb any wear.

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I'm also trying to visualize the cooling air exit geometry, generous radius at the top and aft of the rear cylinders envisioning a curve to align align the exit airflow parallel to the belly.

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You can see my existing firewall-2-belly-bump behind the cardboard, I'm trying to lengthen the convergence of the exit air within the cowling.

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I'm also trying to visualize the cooling air exit geometry, generous radius at the top and aft of the rear cylinders envisioning a curve to align align the exit airflow parallel to the belly.
You can see my existing firewall-2-belly-bump behind the cardboard, I'm trying to lengthen the convergence of the exit air within the cowling.

As I think you know, several of us are using a converging exit duct of significant length. Recent photos show a shorter duct on a certain famous RV-4. Smart aero guys have told me anything much more than a few inches is a waste, as velocity changes in a near-instant fashion at the point of pressure change. In the latter case, the short radius is just to get rid of sharp edges at the exit.

The long duct question seems to be that any theoretical velocity increase may be offset by additional skin friction.

You already have several experiments going. Given the above question, why not go back to flying, get some solid measurements, then add the larger duct later? That way, any subsequent performance change (good or bad) can be attributed to the duct.
 
foam seal

I've never seen foam used on a cowl like this for sealing the propeller shaft. What about heat build up on the shaft from rubbing the foam? Seems like you would want to minimize that. What about shaping a really low density foam to have teeth like a labyrinth seal to minimize contact but still providing a seal? or just eliminating the foam, you have a low diameter gap which is good and will minimize leakage.

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As I think you know, several of us are using a converging exit duct of significant length. Recent photos show a shorter duct on a certain famous RV-4. Smart aero guys have told me anything much more than a few inches is a waste, as velocity changes in a near-instant fashion at the point of pressure change. In the latter case, the short radius is just to get rid of sharp edges at the exit.

The long duct question seems to be that any theoretical velocity increase may be offset by additional skin friction.

You already have several experiments going. Given the above question, why not go back to flying, get some solid measurements, then add the larger duct later? That way, any subsequent performance change (good or bad) can be attributed to the duct.

Interesting.......

Yes, I plan on flight testing 1 change at a time. Just trying to start visualizing my next move.
 
I've never seen foam used on a cowl like this for sealing the propeller shaft. What about heat build up on the shaft from rubbing the foam? Seems like you would want to minimize that. What about shaping a really low density foam to have teeth like a labyrinth seal to minimize contact but still providing a seal? or just eliminating the foam, you have a low diameter gap which is good and will minimize leakage.

labseal_zpsnw25gqyf.png

Good ideas Steve!

Honestly I won't be too surprised if the foam removes itself in one fashion or another, but on the other hand I think it has a chance at working. I'm anticipating the foam to "wear" into shape rather quickly, I should know after the first test run. If it does create too much friction I could modify the seal as you suggested.
My other thought would be to glass in a flange around the spinner to parallel the landoll ring and use baffling material from the flange to the outside of the landoll ring.
I'm not sure I've closed the gap at all, any air escaping still has to exit the 3/16th gap between the spinner and the front of the cowling. I'm not sure making the hole smaller upstream from the spinner gap changes the amount of leakage or not.
 
I caught the last day of MountainHigh Oxygen's Oshkosh sale from home, I used the $$ I was going to spend going to OSH.......
I've found myself spending a decent portion of X/C flights 9000-13,500 and I can really start to feel the beginning signs of hypoxia after 30 minutes. I've done the altitude chamber in OKC and highly recommend anyone to experience hypoxia firsthand. I also would like to be able to chase winds at the higher altitudes and have more options when flying out west.
I chose the pulse demand system with the AL647 bottle, it provides almost 40 hrs of O2 at 10K and 19 hrs at 15K. With 2 people cutting those times in half I should still be able to fly just about anywhere without refilling on the road.

Lots to know about O2, Tim Olson has a great write-up:

http://www.myrv10.com/tips/accessories/oxygen/index.html

Another good read:

http://www.avweb.com/news/pelican/182079-1.html

I also purchased mountain high's basic transfiller. I started off with a friend's freshly filled 125 cubic ft cylinder ($21), it filled my 23 cubic ft cylinder to 1800-1900 PSI. Looks like I'll be buying a second bottle pretty soon for the next fill.

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I'm planning on mounting the bottle to the passenger seat back, it fits but barely. I'm going to have to play with installation and removal of the bottle some more before drilling holes.
 
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