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  #11  
Old 07-25-2020, 09:32 AM
rocketman1988 rocketman1988 is offline
 
Join Date: Jun 2010
Location: Sunman, IN
Posts: 2,397
Default ...ummm

Personal preference?

Going outside the box?

Experimenting?

There are many individual reasons to consider an alternative engine, or other system.

You may not agree with them but that does not matter; you build the way you want and everyone else is free to do the same...the beauty of experimental aviation.
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Aerospace Engineer '88

RV-10
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  #12  
Old 07-25-2020, 10:15 AM
gdrudolph gdrudolph is offline
 
Join Date: Jul 2019
Location: Mountain View, CA
Posts: 7
Default

Quote:
Originally Posted by David Paule View Post
The weight is close to what the O-470 on my C180 weighs, but the power and fuel consumption is a bit higher. It's probably a reasonable engine for an RV-10 or Rocket, but would someone please explain why this would be preferable to a Lycoming IO-540 that you can buy today and which has known service requirements and reliability and for which the aircraft are designed?

I just don't see any advantage to this thing. Anyone?

Dave
A reasonable question as it is just a powerplant at the end of the day... so advantages: Turbo for high level x-country & DA power when you need it most, 4 cylinder (2 less potential points of failure... and less on overhaul but may negate with addition of Turbo), potential ability for Garmin Auto-Land which only works (currently) with Turbo powerplants, less expensive gas (big one), and it looks cool (haha jk)...
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Private Pilots License 1987
25 Year flying hiatus to raise 3 kids
and now the flying "itch" is back!
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  #13  
Old 07-25-2020, 11:54 AM
rmartingt's Avatar
rmartingt rmartingt is offline
 
Join Date: Nov 2006
Location: Savannah, GA
Posts: 1,092
Default

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.
Quote:
Originally Posted by David Paule View Post
The weight is close to what the O-470 on my C180 weighs, but the power and fuel consumption is a bit higher. It's probably a reasonable engine for an RV-10 or Rocket, but would someone please explain why this would be preferable to a Lycoming IO-540 that you can buy today and which has known service requirements and reliability and for which the aircraft are designed?

I just don't see any advantage to this thing. Anyone?
As Ross notes (and leaving aside non-economic reasons like the other Bob notes), you have to look at the cost and weight tradeoffs.

Remember that we here in the US have access to pretty cheap fuel, compared to the rest of the world--especially Avgas, which elsewhere in the world is typically much more expensive than we pay here, if you can get it at all.

By contrast, jet fuel (and its close cousin diesel fuel) are pretty widespread and common elsewhere in the world, and it's typically going to be a fair bit cheaper to boot. An airplane that can run on jet/diesel can provide you with lower fuel costs and better fuel availability.

At that point it becomes a weight and cost tradeoff... if Avgas is really expensive compared to jet fuel where you live, you may well come out ahead in the long run even with the much higher upfront cost of the diesel. If you can't get avgas at all, and a turboprop isn't a viable option, a diesel might be the only realistic way of powering your small airplane.

But at least right now in the US, the higher upfront costs don't seem to be worth the reduction in fuel costs to most operators, especially those who are paying out of pocket and can't depreciate that upfront cost across the operating expenses...
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  #14  
Old 07-25-2020, 01:15 PM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
 
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,905
Default

Quote:
Originally Posted by David Paule View Post
The weight is close to what the O-470 on my C180 weighs, but the power and fuel consumption is a bit higher. It's probably a reasonable engine for an RV-10 or Rocket, but would someone please explain why this would be preferable to a Lycoming IO-540 that you can buy today and which has known service requirements and reliability and for which the aircraft are designed?

I just don't see any advantage to this thing. Anyone?

Dave
The main reason would probably be because you like diesels or want something different. Nothing wrong with that.
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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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  #15  
Old 07-25-2020, 01:17 PM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
 
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,905
Default

Quote:
Originally Posted by rmartingt View Post
As Ross notes (and leaving aside non-economic reasons like the other Bob notes), you have to look at the cost and weight tradeoffs.

Remember that we here in the US have access to pretty cheap fuel, compared to the rest of the world--especially Avgas, which elsewhere in the world is typically much more expensive than we pay here, if you can get it at all.

By contrast, jet fuel (and its close cousin diesel fuel) are pretty widespread and common elsewhere in the world, and it's typically going to be a fair bit cheaper to boot. An airplane that can run on jet/diesel can provide you with lower fuel costs and better fuel availability.

At that point it becomes a weight and cost tradeoff... if Avgas is really expensive compared to jet fuel where you live, you may well come out ahead in the long run even with the much higher upfront cost of the diesel. If you can't get avgas at all, and a turboprop isn't a viable option, a diesel might be the only realistic way of powering your small airplane.

But at least right now in the US, the higher upfront costs don't seem to be worth the reduction in fuel costs to most operators, especially those who are paying out of pocket and can't depreciate that upfront cost across the operating expenses...
Yup, totally agree.

I'd add after several flights in Les Kearney's 540 powered RV-10, even up at 20,000 feet, performance and economy is impressive. I am a big fan of turbos but I don't see that most folks need one on a -10. With the ported heads, cold/ ram air system from Show Planes and EFI/EI, we were seeing 160-172 KTAS on 8.7- 11.3 gph, depending on altitude, running LOP.
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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 : 07-25-2020 at 01:25 PM.
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  #16  
Old 07-25-2020, 10:45 PM
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skylor skylor is offline
 
Join Date: Aug 2009
Location: Southern California
Posts: 959
Default Intake

One thing to keep in mind is that the tall overhead intake will most likely have interference issues with the stock cowling. Reshaping the cowling to accommodate it will most probably add drag to the airframe offsetting at least some of the claimed efficiency gains of the engine. The reshaped cowling will also reduce forward visibility.

Skylor

Last edited by skylor : 07-26-2020 at 12:42 PM.
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  #17  
Old 07-26-2020, 08:16 AM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
 
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,905
Default

I know Scott was having issues getting accurate fuel flow figures in cruise. Would be nice to know if those have been resolved and what the TAS vs. FF is at various altitudes to compare to 540 powered 10s.
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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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  #18  
Old 07-27-2020, 01:44 PM
kgood kgood is offline
 
Join Date: Mar 2009
Location: Boulder City, NV
Posts: 168
Default Why a diesel?

I'll give you a few reasons:
1. Safety: Diesel/JetA is much less flammable or volatile than avgas or mogas. This is a big deal to me. Too many people survive accidents only to be burned.
2. Reliability: Continental and Austro claim fewer in-flight shut downs per 100,000 hours than their traditional counterparts. I've spoken with an operator in Europe who has a fleet of PA28s with CD engines, along with Lycomings. He says his diesels are much more reliable, with more up-time. I've had similar results.
3. Economy: Some folks say that a traditional large bore gas engine running LOP approaches the efficiency of diesel. It's simply not even close, especially when the entire flight profile is considered. Diesels consistently consume 25-30% less fuel. I've done the testing. In most places, JetA costs less as well.
4. Ease of operation: Just start it and drive it like your modern car. No fussing with mixture, prop control, carb heat, mags, hot starts, cold starts, priming, etc. Set the single lever control at the desired percent of power or fuel burn and forget it. Climb, descend, do whatever you want; the system doesn't care.
5. As mentioned by others, the push to eliminate leaded fuels isn't going away. We will eventually need to move to UL fuels, and because of low demand, it'll be more expensive.
6. Service intervals: Modern diesels have 100 hour service intervals, compared to 50 hours with traditional engines.
7. Performance. Because modern aerodiesels are turbocharged, they produce 100% power from SL to 10,000', and then power drops off very slowly. DA is much less of an issue.

Drawbacks: Weight and cost. Weight is not as big a deal as you might think. If my diesel installed weight is 80 lb heavier than the equivalent traditional model (it is), I can just fly with 80 lb less fuel and still go substantially further than my friends. Or I can fill the tanks and stay in the air for 8+ hours at normal cruise, or 10 hours at economy cruise. With regard to cost, fuel savings during the life of the engine can easily offset the extra up-front cost.

I can back up what I'm saying with experience. I've flown experimental diesels since 2008; 600+ hours in an RV9 (WAM 120 diesel) and 760 hours in a Sportsman (CD155 diesel).

As Ross says, some people just like diesels. I'm one of them. I think the OP would be too if he had the chance to fly behind one.

Kurt
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  #19  
Old 07-27-2020, 04:43 PM
Flandy10 Flandy10 is offline
 
Join Date: Dec 2007
Location: Peachtree City, GA
Posts: 145
Default

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.
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Rv-10 TDI 330 hrs
Fayettevile, GA

2021 VAF Donation complete

Last edited by Flandy10 : 07-28-2020 at 07:21 AM. Reason: Deleted last comment
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  #20  
Old 07-27-2020, 06:18 PM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
 
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Location: Calgary, Canada
Posts: 5,905
Default

Good stuff Scott.

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