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looks great, do you have some Pictures Firewall Forward? Looks like a nice installation!
Don't look to close! I still have a good bit of tidying up yet to do... Once I've tested all my electrical, I'll remove most of the cable ties and replace with lacing cord and adel clamps. I have a full Christen inverted oil system, Garmin G3 IFR with all the engine stuff, RV Bits Plenum on a new Lycoming IO-360 spinning an MT CS prop.... Had quite a time getting all the extras on and in place. I did have to re-glass my air box in order to get it centered.... OCD gives me a fit!!!
I now have extreme plenum envy.
I'm looking at the left rear corner of the baffle where the oil cooler is bolted to the baffles - as a few other RV8s I'm suspecting that you may eventually get vertical cracking around the bend. It's hard to tell from the picture if there is a reinforcing angle there that some folks add to fix the crack when they occur or prevent in the first place. You'll likely find the issue if you search the forums.
I was aware of the issue but, I forgot about it until I was past that point. I did have to remove completely the front and rear baffle brace in order to get the plenum to fit. But, after a few e-mails back and forth with Jan at RV Bits he said the plenum itself will take the place of that. So, I'm hoping it will also help with cracking issue in that corner.
I did have a tech visit from Vic Syracuse and he wasn't too impressed with plenums overall.... he said most he has seen caused heating issues.....
I'm setting this plane up for acro and most of my friends say the plenum will keep the cowling from blowing up during the dives...... ????? ......
Do give us a report on that at 500 hours.
I'm sure he meant to say a certain leading brand of plenum and cowl caused heating issues, a function of the inlets leading into the plenum, not the plenum itself.
In truth the plenum is the enclosed space about the engine. A stock Vans cowl installation with flap seals has a plenum, which functions the same as a plenum space with a separate lid, as we see here. That lid is unquestionably a better sealing device, as compared to flap seals.
Looks like your installation uses a standard RV-8 cowl. Measured pressure recovery for the stock cowl is quite good. Here the $100,000 dollar question is how you will seal those well-designed stock cowl inlets to your enclosed plenum space. Done poorly, that fancy plenum lid is just bling.
That is true. A decent set of inlets with tight plenum sealing and tight cylinder baffles will convert 80% or more of the available dynamic pressure to increased static pressure inside the plenum space. At 200 KTAS and 5000 feet on a standard day, that pressure would be 117 lbs per square foot x 0.8, or about 94 lbs. If we assume the lid to be 18" x 30" for a total of 3.75 sq ft, the total force trying to blow the plenum lid off the engine is 352 lbs. Doesn't matter if the plenum lid is a fancy carbon fiber thing tied to the baffle tin, or the upper cowl half.
The load is increased at lower altitude and higher airspeed. If designing sensibly, we probably want to ensure it will handle at least 230 KTAS at 2000 feet, just in case Bubba pulls a split-S from a roll or something. That would be 570 lbs at 0.9 efficiency.
Kinda puts cowls and plenum lids in a different light, eh?
My plan is to use some gap seal from McMaster Carr along the top edges of the baffle slop to the cowl ramp and along the front edge of plenum at the inlet to provide a positive seal between the two. .... I have several different shapes and sizes to see what, (if any) works best.
So far I've spent way to much time shaping, fitting and head scratching between the baffles, the "lid", the top cowl and the inlet ramps.... I finally just quit and figured I'd get back to that later.....
It will absolutely, positively, unquestionably be more of a PITA later. Figure out a sure plan and do whatever it takes, now, at home, in your shop.
We've been finishing a few post-paint tasks off in the workshop - hoping to take this to the airfield in the next few weeks.
Thanks Greg, the blue is a Jaguar Cars colour called Caesium Blue.
The scheme was from Scheme Designers. Craig Barnett was tremendous to work with, and just kept tweaking it till we had the perfect solution. I had always liked one particular scheme that he had come up with Peter Fruehling's RV-7, and that inspired some ideas specifically adapted to an RV-8 (with the annoying UK requirement for a large fuselage registration).