X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 11 Sep 2005 09:26:54 -0400 Message-ID: X-Original-Return-Path: Received: from web81208.mail.yahoo.com ([206.190.37.181] verified) by logan.com (CommuniGate Pro SMTP 5.0c2) with SMTP id 717458 for lml@lancaironline.net; Sat, 10 Sep 2005 01:28:49 -0400 Received-SPF: none receiver=logan.com; client-ip=206.190.37.181; envelope-from=compositeguy@sbcglobal.net Received: (qmail 24987 invoked by uid 60001); 10 Sep 2005 05:27:59 -0000 X-Original-Message-ID: <20050910052759.24985.qmail@web81208.mail.yahoo.com> Received: from [69.110.53.99] by web81208.mail.yahoo.com via HTTP; Fri, 09 Sep 2005 22:27:58 PDT X-Original-Date: Fri, 9 Sep 2005 22:27:58 -0700 (PDT) From: daniel newland Subject: Re: [LML] Re: Another way to look at the Innodyne X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-573211110-1126330078=:24961" Content-Transfer-Encoding: 8bit --0-573211110-1126330078=:24961 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Hi Mike Thanks for the input! I checked their website and Innodyn has revised their data as to fuel burn and it is stated as quite a bit higher now but still low of what these numbers suggest. I had also early on asked about power output as a function of altitude which tehy couldn't provide. Since they use the same core, I would assume that the 255 HP probably doesn't have a lot of excess rated HP so that you get all 255 horses up to some altitude. Maybe the lower rated versions do that. Oh well, on to diesels... My concern is largely driven by availability of AVGAS. And of course the potential for a lot less wear and broken parts on the turbines. Mike Hutchins <210flyer@earthlink.net> wrote: st1\:*{behavior:url(#default#ieooui) } Hi Dan, I think your fuel flow assumptions are overly optimistic. In addition, the power output of the turbine will degrade with altitude just like a normally aspirated piston engine. The exception is if the turbine has a power limit at lower altitudes, often due to inter-turbine temperatures, then it will behave more like a turbonormalized engine where it will produce rated power up to some critical altitude and then degrade with additional altitude. As Gary points out, your fuel flow estimate requires a BSFC of 0.38 (using a Jet A density of ~ 6.9Lbs/Gal) which is very unlikely. In comparison, the Walter only achieves a BSFC around 0.67 Lbs/Hp/Hr. Using this figure, your Innodyne 255TE will be sucking down 24 gal/Hr. On their website, Innodyne reports a flight average fuel consumption of 7 Gal/100 Hp/Hr which equates to an average BSFC of 0.48 Lbs/HP/Hr. This would amount to 17.7 GPH at takeoff and would decrease to 12.4 GPH at 12,000’ which would be equivalent to 70% power, assuming the engine is not derated. I think the new Williams engines, such as the FJ33 and FJ44 are achieving BSFCs around 0.55 (though I can’t confirm the BSFC figure), which is almost 15% higher than the Innodyne BSFC yet 18% lower than the Walter BSFC. Using the 0.55 value, your fuel flows would be ~ 20 GPH at full power and ~ 14 GPH at 12,000’ and maximum power of 70% (or ~180HP). Like Gary, I think these numbers will hit closer to the mark when Innodyne publishes the BSFC for its production turbines. Also, don’t forget that Jet-A weighs about a pound more per gallon than 100LL, so your useful load with full fuel will be less, offsetting some of the weight saved from the lighter engine. We’re getting closer to a practical turbine engine for GA aircraft, and certainly Innodyne may be the closest when it comes to the smaller SHP engines. Unfortunately, I think it may be many years before we see a turbine that rivals the efficiency of our “modern” piston aircraft engines. Best Regards, Mike --0-573211110-1126330078=:24961 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: 8bit
Hi Mike
 
Thanks for the input!  I checked their website and Innodyn has revised their data as to fuel burn and it is stated as quite a bit higher now but still low of what these numbers suggest.  I had also early on asked about power output as a function of altitude which tehy couldn't provide.  Since they use the same core, I would assume that the 255 HP probably doesn't have a lot of excess rated HP so that you get all 255 horses up to some altitude.  Maybe the lower rated versions do that.  Oh well, on to diesels...
 
My concern is largely driven by availability of AVGAS.  And of course the potential for a lot less wear and broken parts on the turbines.

Mike Hutchins <210flyer@earthlink.net> wrote:

Hi Dan,

 

I think your fuel flow assumptions are overly optimistic. In addition, the power output of the turbine will degrade with altitude just like a normally aspirated piston engine. The exception is if the turbine has a power limit at lower altitudes, often due to inter-turbine temperatures, then it will behave more like a turbonormalized engine where it will produce rated power up to some critical altitude and then degrade with additional altitude.

 

As Gary points out, your fuel flow estimate requires a BSFC of 0.38 (using a Jet A density of ~ 6.9Lbs/Gal) which is very unlikely. In comparison, the Walter only achieves a BSFC around 0.67 Lbs/Hp/Hr. Using this figure, your Innodyne 255TE will be sucking down 24 gal/Hr. On their website, Innodyne reports a flight average fuel consumption of 7 Gal/100 Hp/Hr which equates to an average BSFC of 0.48 Lbs/HP/Hr. This would amount to 17.7 GPH at takeoff and would decrease to 12.4 GPH at 12,000’ which would be equivalent to 70% power, assuming the engine is not derated. I think the new Williams engines, such as the FJ33 and FJ44 are achieving BSFCs around 0.55 (though I can’t confirm the BSFC figure), which is almost 15% higher than the Innodyne BSFC yet 18% lower than the Walter BSFC. Using the 0.55 value, your fuel flows would be ~ 20 GPH at full power and ~ 14 GPH at 12,000’ and maximum power of 70% (or ~180HP). Like Gary, I think these numbers will hit closer to the mark when Innodyne publishes the BSFC for its production turbines.

 

Also, don’t forget that Jet-A weighs about a pound more per gallon than 100LL, so your useful load with full fuel will be less, offsetting some of the weight saved from the lighter engine.

 

We’re getting closer to a practical turbine engine for GA aircraft, and certainly Innodyne may be the closest when it comes to the smaller SHP engines. Unfortunately, I think it may be many years before we see a turbine that rivals the efficiency of our “modern” piston aircraft engines.

 

Best Regards,

Mike

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