X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 09 Sep 2005 20:41:33 -0400 Message-ID: X-Original-Return-Path: <210flyer@earthlink.net> Received: from smtpauth05.mail.atl.earthlink.net ([209.86.89.65] verified) by logan.com (CommuniGate Pro SMTP 5.0c2) with ESMTP id 717116 for lml@lancaironline.net; Fri, 09 Sep 2005 17:04:37 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.65; envelope-from=210flyer@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=tWEeZF/1wRIgj3AULaWLzFQpx3unlz/a+ppk/E0DhKqfRj/P6dljHJgiToPl6uag; h=Received:From:To:Subject:Date:MIME-Version:Content-Type:X-Mailer:thread-index:X-MimeOLE:In-Reply-To:Message-ID:X-ELNK-Trace:X-Originating-IP; Received: from [68.166.211.175] (helo=dune) by smtpauth05.mail.atl.earthlink.net with asmtp (Exim 4.34) id 1EDq2K-00078L-KP for lml@lancaironline.net; Fri, 09 Sep 2005 17:03:53 -0400 From: "Mike Hutchins" <210flyer@earthlink.net> X-Original-To: "Lancair Mailing List" Subject: RE: Another way to look at the Innodyne X-Original-Date: Fri, 9 Sep 2005 15:03:45 -0600 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00CB_01C5B54F.AD42D7D0" X-Mailer: Microsoft Office Outlook, Build 11.0.6353 thread-index: AcW1JenTLq9uUgxCTKGt0FiKa5Y+mgAVrfow X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2670 In-Reply-To: X-Original-Message-ID: X-ELNK-Trace: 96606e18df264d301aa676d7e74259b7b3291a7d08dfec796b2868f020665cd88333662d091e81b0350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 68.166.211.175 This is a multi-part message in MIME format. ------=_NextPart_000_00CB_01C5B54F.AD42D7D0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 ------=_NextPart_000_00CB_01C5B54F.AD42D7D0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

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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