X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 07 Jun 2011 14:18:26 -0400 Message-ID: X-Original-Return-Path: Received: from nm26-vm5.bullet.mail.ne1.yahoo.com ([98.138.91.248] verified) by logan.com (CommuniGate Pro SMTP 5.4.0) with SMTP id 5011902 for lml@lancaironline.net; Tue, 07 Jun 2011 07:46:58 -0400 Received-SPF: none receiver=logan.com; client-ip=98.138.91.248; envelope-from=casey.gary@yahoo.com Received: from [98.138.90.55] by nm26.bullet.mail.ne1.yahoo.com with NNFMP; 07 Jun 2011 11:46:22 -0000 Received: from [98.138.89.195] by tm8.bullet.mail.ne1.yahoo.com with NNFMP; 07 Jun 2011 11:46:22 -0000 Received: from [127.0.0.1] by omp1053.mail.ne1.yahoo.com with NNFMP; 07 Jun 2011 11:46:19 -0000 X-Yahoo-Newman-Property: ymail-5 X-Yahoo-Newman-Id: 51791.74643.bm@omp1053.mail.ne1.yahoo.com Received: (qmail 64228 invoked by uid 60001); 7 Jun 2011 11:46:18 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=0j/50ZV2FNyxgUO/TVyNoZXGM93JlH+zGH8yOiMsmxufSVUlXsS7NElajwssAm/Y9A+vOglP2aTZRKwd7qvG5hfIUdU+CvG5HvvBlapDBzpm8QAjGCLt39i1UivXmCNi6AcMKmxZungrgRqKNSqkiTdBmhRM9XZb+D2v0i/xc+c=; X-Original-Message-ID: <868704.59461.qm@web125607.mail.ne1.yahoo.com> X-YMail-OSG: ThHxLSkVM1ncKYMT3_lKusB_v.ZZykT7QCbngnmwZIR0cvf 4TNQyV5zb.FjdQx2sSJyUsqOHRkLIfDles1mt80t0EmZMBpCRdmaII_ayz2L j8Stm6TnmzptLaw.UYq1FXqg_tt132rDeIf6KeGPHZIhgHSsx9uCQ4udva84 uAcbNio7mk0pxLZiNQvc69Gwlw1snRwhB6RWxfKrs6wHATgzrrJQyKTRt14s D3xoqLnWEcVWZpBwZPMOI.9vO8JNBaspvjKhsXDadjDQT0R2oujRnZ0FQ0mt ZJ.BP.X_P33jJSxpTSivWsVtapb84hZiGAVx3c4wEKw36Cxdn6aQ- Received: from [97.122.154.57] by web125607.mail.ne1.yahoo.com via HTTP; Tue, 07 Jun 2011 04:46:18 PDT X-Mailer: YahooMailRC/570 YahooMailWebService/0.8.111.303096 References: X-Original-Date: Tue, 7 Jun 2011 04:46:18 -0700 (PDT) From: Gary Casey Subject: Re: L-IV Choice of Engine X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-565793667-1307447178=:59461" --0-565793667-1307447178=:59461 Content-Type: text/plain; charset=us-ascii Ted, Yes, it is a fun conversation and could go on forever :-) Sorry about the various text colors - I don't know how to fix all that stuff. My comments are based mostly on a narrow horsepower range of about 350 that I targeted for my ES, so they may not be valid for other hp ranges (like the 600 hp Eagle). But: Matching the air-cooled engines BSFC is difficult - it is a low friction, low surface-to-volume ratio engine running reasonably hot (hot internal surface temperatures reduce heat rejection and improve BSFC). I doubt that a liquid-cooled engine could match the BSFC of a modern air-cooled engine running LOP. I designed a direct-drive V-8 installation, and at the hp target I was (and am) convinced it was a better choice than a package with a speed reduction. A V8 can tolerate a lot of boost so a 400 cu.in. Chevy running about 50 inches manifold pressure can produce a reliable 350 hp at 2800 rpm. I agree with the comments on rotary engines. They have one advantage, which I consider important, and that is that they can continue to produce power with substantial damage. This would include apex seal failure and loss of coolant. I piston engine will likely not last long without coolant. But as for parts count, I once counted 50 parts in a single rotor. Production rotary engines, to my knowledge, are not tolerant of crankshaft (oops, "e-shaft", pardon me) thrust, so allowances have to be made. Yes, the noise level can be tolerable with an added turbocharger, but the high exhaust temperatures require a high-temperature turbine housing (and probably a liquid-cooled center section) and even then it can be marginal. One advantage of air-cooled engines is that they have a gradual over-temp limit, while liquid-cooled engines have an absolute limit (boiling). With an absolute limit you have to go to great pains to stay away from the limit, even for a short time. This might have to include an electric cooling fan for ground operation, but what do you do in the air? Most likely oversize the cooling system to maintain an adequate margin, and this adds weight and cooling drag. Gary Casey >From Ted: >This is a fun conversation. > >On 6/4/2011 9:52 AM, Gary Casey wrote: >My conclusions - opinions of the disadvantages: >> >>V-8 with reduction gear: >>Heavy - about 150 pound penalty >>Complex installation and systems >>Slight fuel consumption penaltyweight, 400 HP. Eagle 540 700# wet, 600 hp. A >>comparably sized automotive derivative engine can easily be lighter hp for hp. >>Because of internal design elements (advances in design possible because of >>liquid cooling, i.e. no gas used for cooling) modern liquid cooled engines can >>easily match or improve on air-cooled gas consumption. > > >>V-8 engine direct drive turbocharged: >>Heavy - about 75 pound penalty >>Complex installation and systemsNo information, so I can't comment. The only one >>I could find was the WW1 Hispano-Suiza. Hardly relevant to the conversation. >Rotary engine: >Very complex installation and systems >Heavy - up to 50 pound penalty >Potentially fragile apex seals >Hgh cooling drag >Noisy >Significant fuel consumption penalty increases the weight penaltyMazda 13B >engine FWF weight 325 # all up (200 HP. I couldn't find the 20B data quickly) >The equivalent engine is the Lycoming IO-360 at 324-335 #. Sounds like a wash, >or maybe a slight win for the rotary. Yes, the rotary is slightly thirsty, but >the gap seal issue is ancient history. The newer engines have been bulletproof. >Turbine engine: >High initial cost >High fuel consumption negates any weight savingsAmen. >Misc. opinions: The liquid-cooled V-8 dates back to about 1918 when Chevrolet >built the first mass-produced one, so it's technology is even older than the >air-cooled engine's "30's technology" that someone mentioned.That may be true, >but the resemblance between then and now is mostly coincidental. Liquid cooling >has allowed major advances in design that are largely missing from air-cooled >engines. Now part of the blame on the air-cooled side is due to regulatory >ossification, but until completely new materials (e.g. ceramics) come into play, >there's not much to gain. Choke can't go away, because the head of the cylinder >will always be hotter than the base. Exhaust valve troubles won't go away >because the cooling gradient between the valve and the head is so low compared >to liquid cooled engines. The basic laws of physics just don't change. The >constraints they impose limit solutions. >Gary Casey ________________________________ > --0-565793667-1307447178=:59461 Content-Type: text/html; charset=us-ascii
Ted,
Yes, it is a fun conversation and could go on forever :-)
Sorry about the various text colors - I don't know how to fix all that stuff.  My comments are based mostly on a narrow horsepower range of about 350 that I targeted for my ES, so they may not be valid for other hp ranges (like the 600 hp Eagle).  But:
Matching the air-cooled engines BSFC is difficult - it is a low friction, low surface-to-volume ratio engine running reasonably hot (hot internal surface temperatures reduce heat rejection and improve BSFC).  I doubt that a liquid-cooled engine could match the BSFC of a modern air-cooled engine running LOP.
I designed a direct-drive V-8 installation, and at the hp target I was (and am) convinced it was a better choice than a package with a speed reduction.  A V8 can tolerate a lot of boost so a 400 cu.in. Chevy running about 50 inches manifold pressure can produce a  reliable 350 hp at 2800 rpm.
I agree with the comments on rotary engines.  They have one advantage, which I consider important, and that is that they can continue to produce power with substantial damage.  This would include apex seal failure and loss of coolant.  I piston engine will likely not last long without coolant.  But as for parts count, I once counted 50 parts in a single rotor.  Production rotary engines, to my knowledge, are not tolerant of crankshaft (oops, "e-shaft", pardon me) thrust, so allowances have to be made.  Yes, the noise level can be tolerable with an added turbocharger, but the high exhaust temperatures require a high-temperature turbine housing (and probably a liquid-cooled center section) and even then it can be marginal.
One advantage of air-cooled engines is that they have a gradual over-temp limit, while liquid-cooled engines have an absolute limit (boiling).  With an absolute limit you have to go to great pains to stay away from the limit, even for a short time.  This might have to include an electric cooling fan for ground operation, but what do you do in the air?  Most likely oversize the cooling system to maintain an adequate margin, and this adds weight and cooling drag.
Gary Casey

From Ted:
This is a fun conversation.

On 6/4/2011 9:52 AM, Gary Casey wrote:

My conclusions - opinions of the disadvantages:

 

V-8 with reduction gear:

Heavy - about 150 pound penalty

Complex installation and systems

Slight fuel consumption penalty

weight, 400 HP.  Eagle 540 700# wet, 600 hp. A comparably sized automotive derivative engine can easily be lighter hp for hp. Because of internal design elements (advances in design possible because of liquid cooling, i.e. no gas used for cooling) modern liquid cooled engines can easily match or improve on air-cooled gas consumption.

 

V-8 engine direct drive turbocharged:

Heavy - about 75 pound penalty

Complex installation and systems

No information, so I can't comment. The only one I could find was the WW1 Hispano-Suiza. Hardly relevant to the conversation.

 

Rotary engine:

Very complex installation and systems

Heavy - up to 50 pound penalty

Potentially fragile apex seals

Hgh cooling drag

Noisy

Significant fuel consumption penalty increases the weight penalty

Mazda 13B engine FWF weight 325 # all up (200 HP. I couldn't find the 20B data quickly) The equivalent engine is the Lycoming IO-360 at 324-335 #. Sounds like a wash, or maybe a slight win for the rotary. Yes, the rotary is slightly thirsty, but the gap seal issue is ancient history. The newer engines have been bulletproof.

 

Turbine engine:

High initial cost

High fuel consumption negates any weight savings

Amen.

 

Misc. opinions:  The liquid-cooled V-8 dates back to about 1918 when Chevrolet built the first mass-produced one, so it's technology is even older than the air-cooled engine's "30's technology" that someone mentioned.

That may be true, but the resemblance between then and now is mostly coincidental. Liquid cooling has allowed major advances in design that are largely missing from air-cooled engines. Now part of the blame on the air-cooled side is due to regulatory ossification, but until completely new materials (e.g. ceramics) come into play, there's not much to gain. Choke can't go away, because the head of the cylinder will always be hotter than the base. Exhaust valve troubles won't go away because the cooling gradient between the valve and the head is so low compared to liquid cooled engines. The basic laws of physics just don't change. The constraints they impose limit solutions.

 

Gary Casey


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