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RV10 Cold Air Induction - Showplanes Cowl

RyanWhite

RyanWhite

Active Member
Anyone running Showplanes Cowl w/ cold air induction? Is it worth it? What prop - how about some real world numbers? I know - every plane is different and the rigging has a lot to do with speed. The big question is it worth it to do the showplanes cowl w/ CAI?

The mission is cross country so performance and efficiency is the name of the game.
 
yes

Hartzell 3 blade, 9:1, CAS, 1 Surefly, 1 Slick Mag Showplanes Cowl.

KTAS 177 @9000 12.5GPH ROP 2300/24.5 is my Fast cruise

KTAS 165 @9000 10.5GPH LOP 2300/24.5 economy cruise.

It'll go faster but I haven't done much real flat out flying so not a lot of data.

Thats mid weight, say two people and bags, full fuel. Its reliably 1-2 quicker solo and half tanks, and 1-2 slower at gross.

I gave a lot of thought to minimising drag.
I have a plenum
tight cowl/spinner gap (1/8)
two blade antennas - one a combined com/gps, nothing else external.

I'd assumed the 3blade would cost me performance, but Im comfortably seeing book numbers - if not slightly better - so I'm happy.

climb performance - especially light - is remarkable. Leaves my RV7 for dead. :)
 
numbers

Barrett IO-540, 9:1, CAI, EFII, MTV-9-B prop, ShowPlanes Cowl and Induction.

I do not have a plenum.

174 KTAS, WOT, 2450 rpm, 11.6 gph, LOP @ 8500'
 
Not planning on AC

So I'm not planning on AC thats why I'm toying around with the idea of Showplanes cowl. Really trying to determine if there is a performance increase with cold air induction and if its worth the extra work.

Maybe a better question for those that have done it - would you do it again?
 
I ordered my Cold Air Induction IO-540 from Thunderbolt over 2 1/2 years ago. Still waiting. If you want to go down this road I suggest getting your order in now.

On the first RV-10 I used the James Cowl with the then standard vertical injection IO-540. I was happy with the result. On the new RV-10 I engaged Jimmy at James Cowl to modify the previous RV-10 offering to accommodate the Cold Air Sump engine. That cowl, along with plenum and James wheel pants have been sitting in the hangar for over six months now.

Carl
 
bjdecker said:
Remember the Aussie conversion factor... :)
Click to expand...
:)

IMG_8532.jpeg

That’s not a knife…. :)

While I’m at it…
I think the showplanes cowl install is no different to the
Vans cowl in terms of difficulty. It’s a very well made piece of glass.
It’s of higher quality out of the box than my experience with Vans cowls.

Intakes - I have an FM300 so things are tight. I’ve relieved the cores in a few select spots to prevent the intakes from rubbing on the cowl. I believe if you have an SDS there’s more room.

IMHO the cowl looks much better than the standard. The 15” spinner looks much more in proportion to the airframe.

You need a specific exhaust. Be aware that the exhaust is close to the cowl in a few places so appropriate shielding is necessary to prevent heat damage to the cowl.

I split my SP lower cowl as I have a 3bladed prop. In practise I’ve only split it once in service. I can now happily manipulate the lower cowl off in one piece. I’m not sure whether I’d do that again if I knew what I know now. 50/50.
As long as you have a long enough gear leg slot it’s doable in one piece.
 
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Is there a snubber or restrictor installed in front of the MAP sensor — and is the MAP sensor a Kavlico P4055-30A-E4A?

What’s going on at 59” into the flight? MAP goes WAY up for quite a while…physics got suspended over Ayer’s rock?
 
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bjdecker said:
Is there a snubber or restrictor installed in front of the MAP sensor — and is the MAP sensor a Kavlico P4055-30A-E4A?

What’s going on at 59” into the flight? MAP goes WAY up for quite a while…physics got suspended over Ayer’s rock?
Click to expand...

Maybe I shouldn’t bother…
Flight started off at 5k and partial throttle due fzl.
That mysterious jump in MAP is likely due to me pushing the black lever to WOT as I climbed from 5k to 9k
Yes it’s a P4055-30A-E4A with an Omega PS-8G installed at the sensor end of the MAP line.

I should have probably just said WOT rather than specify an actual MAP. Jut grabbed the last flight at altitude I had. I don't target MAP I just fly WOT all the time unless (as in this case) Im held low for some reason. ATC or FZL. In that case I tend to target top of the green arc (which for this flight was around 24.5") at TOC it was 24.5 too.
I really can't be bothered plotting WOT MAP vs PAlt for all the flights I have - but if someone wants to script something up they are welcome to all the data. Im confident its above ambient. How much who knows.

Back to the OPs question tho - you guys have got many hundreds of tens flying around, surely some of you could get together and compare configurations.

My back of the envelope calcs suggest that my 285HP 9:1 with CAI should yield me an extra 6.5kts above the 260HP. People said I'd lose 5-6Kts because of the Hartzell 3 blade (I think that's likely to much). Turns out I'm a few knots quicker than book - so maybe the cowl/induction/larger spinner is worth a knot or two. But who knows without side by side comparisons.

Yes before anyone asks I did the NTPS PEC testing in phase 1 and its small across the range ( +0.6 at 155 KCAS ie quicker than indicated )
 
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Richard Connell said:
https://apps.savvyaviation.com/flights/shared/flight/7342603/c22d47e2-220d-4e8a-9a97-2ed45a15069a

I have no reason to doubt the instrumentation. Standard Garmin setup.
MAP off the rear of #5

To be fair this was a high QNH day (30.45) so the pressure alt was 8500.
Click to expand...

Ps @ 8500 ft Std Day = 21.8 in. hg
V=177 ktas = 298.5 ft/s
rho=0.00184 slug/ft^3

q = 1/2 rho V^2 = 82 PSF = 1.16 in. Hg.

Pt = Ps + q = 22.96 in. Hg. So, if you are getting full 100% ram rise in your induction, the highest your MAP could be would be 23 in. Hg.

We do see some elevation above full ram pressure in cold-air induction systems with tapered runners if the RPM is just right to get some wave augmentation - but not 1.5" I don't think.
 
While there is a bump in HP with the CAS IO-540, my objective for going with the Sam James cowl is drag reduction.

To the OPs question, are there any RV-10 guys out there that have some cruise data that compares the stock RV-10 cowl with a buddy that is flying along side with the Show Planes cowl?

Carl
 
scsmith said:
Ps @ 8500 ft Std Day = 21.8 in. hg
V=177 ktas = 298.5 ft/s
rho=0.00184 slug/ft^3

q = 1/2 rho V^2 = 82 PSF = 1.16 in. Hg.

Pt = Ps + q = 22.96 in. Hg. So, if you are getting full 100% ram rise in your induction, the highest your MAP could be would be 23 in. Hg.

We do see some elevation above full ram pressure in cold-air induction systems with tapered runners if the RPM is just right to get some wave augmentation - but not 1.5" I don't think.
Click to expand...

So that realistically leaves sensor error (unlikely) or the placement of the takeoff. Perhaps the snubber acts as a form of check valve through the intake pulse cycle. Or perhaps it’s linked to the higher idle MAP shown by 540s to 360s.
I’ll put it on the list of mysteries to solve at a later date.
 
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