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  #21  
Old 07-27-2020, 07:06 PM
rocketman1988 rocketman1988 is offline
 
Join Date: Jun 2010
Location: Sunman, IN
Posts: 2,401
Default Diesel

I am following the diesels with great interest, although it is likely not going to happen on my -10 any time soon...
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  #22  
Old 07-27-2020, 07:09 PM
andrewtac andrewtac is offline
 
Join Date: May 2014
Location: Friendswood TX
Posts: 315
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Quote:
Originally Posted by rv6ejguy View Post
Good stuff Scott.

Have any TAS/FF figures up higher? We've done most of our testing up at 12-16,000.

I'd like to know too, 170+ is important to me.
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  #23  
Old 07-27-2020, 07:42 PM
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rv6ejguy rv6ejguy is offline
 
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,908
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As a point of reference we've seen around 170 KTAS on 9.6 gph at 16,000 with the 540 running around 30-50 LOP and timing at 30 BTDC. MT 3 blade prop.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 445.9 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
https://www.youtube.com/channel/UCiy...g2GvQfelECCGoQ


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  #24  
Old 07-27-2020, 08:03 PM
Flandy10 Flandy10 is offline
 
Join Date: Dec 2007
Location: Peachtree City, GA
Posts: 145
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Sorry Ross, that data will have to wait for the production turbo.
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  #25  
Old 07-27-2020, 08:11 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,884
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Quote:
Originally Posted by Flandy10 View Post
Well said Kurt!

For those LYC drivers that like messing around with hot and cold start procedures, you wouldn't like it. It just starts- first time, every time. The one time it gave me trouble was when I forgot to turn on the glow plugs at 30F OAT. It still started, just wasn't happy for a few revolutions.

Ross- I'm narrowing in a FF system that is pretty accurate right now. I just need a small computer to translate Marine computer speak to Garmin aviation and it will be VERY accurate. I do like reading about your work on making the Lycosarus modern and more efficient.

The following is just a non-scientific data point comparison from G3X data.

Local IO540 with Hart. 2-blade. 6500Ft. 155Ktas 11 GPH

My CD-230 with MT 3-blade 6500ft. 155Ktas 8.3GPH

-Went 9 hours RT to WI last weekend on 75 gals cruising at 155ktas- do the math...

-I know some of you will say " But I can cruise at 170Ktas+" Great.. but at what GPH and $/gal. How much sooner will it get you there?


Here is the current cowling designed using only my Mark1 eyeball and 286 synaptic processor. No CAD/Solidworks/ etc.... Is it a standard Vans cowl? No. but it IS in there.

No I don't have the big plenum yet but nothing is final until CMI say it is. Being an Alpha tester for this engine, I do get to talk to the guys that make the decisions and continually advocate for things that make sense to me.

Everybody is free to have their own opinion (First Amendment is still in effect) and we can find their own way in this EXPERIMENTAL world.
I can’t see a 30% efficiency improvefor diesel. If diesels were that much better, they would be common place in carsand likely carry tax incentives. As a datapoint with my 10, i cruise at 8000’ at 165 kts and a bit over 10.5 gph. I haven’t really flown much at 155, but i bet my burn would be around 9. I don’t believe that 155 kts at 11 is typical for a 10.

Larry
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Last edited by lr172 : 07-27-2020 at 08:16 PM.
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  #26  
Old 07-27-2020, 08:18 PM
lr172 lr172 is offline
 
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Location: Schaumburg, IL
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Quote:
Originally Posted by rv6ejguy View Post
As a point of reference we've seen around 170 KTAS on 9.6 gph at 16,000 with the 540 running around 30-50 LOP and timing at 30 BTDC. MT 3 blade prop.
We flew at 14k on a recent trip. We were doibg 165kts at around 9.3.
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  #27  
Old 07-27-2020, 08:27 PM
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rv6ejguy rv6ejguy is offline
 
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Location: Calgary, Canada
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Quote:
Originally Posted by lr172 View Post
We flew at 14k on a recent trip. We were doibg 165kts at around 9.3.
Pretty similar to our numbers. Thanks for the data point.

Slowing from 165 to 155 should reduce power needed by about 17% and FF as well, assuming the same BSFC. That would make FFs under 8 gph.

The diesel should have a bigger advantage in the climb where it doesn't have to be rich like an SI engine. Since RVs climb pretty well, the time in the climb isn't so big unless you're going really high.

On the decent, the SI engine can pull power way back whereas the diesel has to maintain pretty high manifold pressure to stay lit in the cold.

Would be most interesting to do a side by side with the same prop. See how much both planes take at the pump (weight not volume, since BSFC is measured lbs./hp/hr. and diesel fuel weighs 10% more than 100LL) at the end of the flight. Make it apples to apples with the SI engine having EFI and proper EI with LOP advance so it's latest SI tech vs. latest diesel tech.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 445.9 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
https://www.youtube.com/channel/UCiy...g2GvQfelECCGoQ



Last edited by rv6ejguy : 07-27-2020 at 08:49 PM.
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  #28  
Old 07-28-2020, 02:06 PM
gfb gfb is offline
 
Join Date: Jul 2014
Location: Madison, WI
Posts: 751
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Any chance you can offer a status update? I'd love to know what Conti is planning on doing. Have they indicated when they will swap you out for the production engine?

Any idea if there will be a FW-FWD kit? cowling molds? engine mount? I understand you sourced/designed all of this on your own so far?
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  #29  
Old 07-28-2020, 02:45 PM
Northernliving Northernliving is offline
 
Join Date: May 2005
Location: Boston, MA
Posts: 507
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Quote:
Originally Posted by rv6ejguy View Post
11.7 gph at 225 hp is a BSFC of .34. We're seeing figures of around .38 with 9 to 1 Lycomings running LOP with EFI and EI. So that's about 10% better for the diesel in cruise. So you'd have to see what the weight and cost trade offs would be.
Different fuels have different energy densities, so wouldn't you have to normalize for the difference between 100LL and the more energy-dense Jet A to get comparable efficiency numbers?
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  #30  
Old 07-28-2020, 02:50 PM
jacoby jacoby is offline
 
Join Date: Jul 2018
Location: WNC
Posts: 297
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Quote:
Originally Posted by lr172 View Post
I canít see a 30% efficiency improvefor diesel. If diesels were that much better, they would be common place in carsand likely carry tax incentives. As a datapoint with my 10, i cruise at 8000í at 165 kts and a bit over 10.5 gph. I havenít really flown much at 155, but i bet my burn would be around 9. I donít believe that 155 kts at 11 is typical for a 10.

Larry
It is possible. it comes down to a few factors: energy/volume, compression ratio, and mixture. diesel (38.6 MJ/L) and jet a (35) both have a higher energy density than 100LL (31.6). So you're looking at 22% more energy for diesel and ~11% for Jet A over 100LL.

Compression ratio: the io-540 is 8.5:1. I don't know what the cd-265 runs at but it's probably somewhere around 1.5x that (12:1ish). so you get more bang per bang.

Finally mixture: diesels don't care. you control power with fuel alone. so you can go WAY LOP and keep running.

There are other efficiencies that apply here too: turbo helps push air into the engine along with 50+ years of engine development since the 540 was designed.

diesels are VERY common in cars including tax incentives.. outside the US. even within the US diesels rule where fuel efficiency really matters: tractor trailers. But for cars diesel runs some 10-20% more to buy/gallon plus the extra $5-10k for the engine and it's a really bad value proposition. You have to drive a lot before you even break even.

they're a great fit for general aviation though: cheaper fuel (jet a), lower burn rate, lots of torque at low RPMs.
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