X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imo-m20.mx.aol.com ([64.12.137.1] verified) by logan.com (CommuniGate Pro SMTP 5.0.9) with ESMTP id 1154209 for flyrotary@lancaironline.net; Wed, 14 Jun 2006 12:29:46 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.1; envelope-from=ARGOLDMAN@aol.com Received: from ARGOLDMAN@aol.com by imo-m20.mx.aol.com (mail_out_v38_r7.5.) id q.2a6.4b74d12 (39331) for ; Wed, 14 Jun 2006 12:28:54 -0400 (EDT) From: ARGOLDMAN@aol.com Message-ID: <2a6.4b74d12.31c19346@aol.com> Date: Wed, 14 Jun 2006 12:28:54 EDT Subject: Re: [FlyRotary] Re: compression ratios To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1150302534" X-Mailer: 9.0 Security Edition for Windows sub 5314 X-Spam-Flag: NO -------------------------------1150302534 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 6/14/2006 10:14:27 A.M. Central Standard Time, kenpowell@comcast.net writes: Steve, I think you are overestimating the power loss of converting over to NA. See this link: _http://www.442.com/oldsfaq/ofcrc.htm_ (http://www.442.com/oldsfaq/ofcrc.htm) . My understanding is that you will only suffer a 2.4 -4.2 HP loss if assuming the NA engine produced 200 HP (depending on a comparison of 9.4 rotors or 9.7 rotors as opposed to the 9.0 turbo rotors). Compression ratio is much overated if you are not trying to make up for radical cam profiles in piston engines. The decision to turbocharge/supercharge, or not really depends on one main thing. Like most decisions aeronautical, it depends on your purposed mission for the aircraft. If your goal is to fly high and far most of the time, t/s charging is a great advantage. There are some drawbacks and those are mainly winds. When they are tail winds, they help you greatly. When they are headwinds, sometimes even with a 200+K plane, you are better off driving. As we all know, tail winds exist only for other people. The other problem is the time, and fuel necessary to climb to the high altitudes. The third is the need for O2, wonderful in theory and if you are up there, necessary, but a real pain in the a--nose in that you are breathing very dry air, in a dry environment and you dehydrate quickly. Bad on a long trip. Make sure that you bring lots of liquid, and a way to eliminate it since all will not be eliminated through your sweat glands and lungs. Of course if you are high enough the nasal canula is not approved so you must wear a mask. Then you must take it off to drink, etc. Because of your altitude, you must plan your letdowns far in advance. you will be IFR and will for the most part be using High Altitude charts (or GPS direct). The OAT will be considerably colder so that heater which was marginal now becomes useless. O2 is somewhat expensive and unless you have your own filling mechanism, available only at specific locations. If you are using a lyco/conti saur, fuel flow and maintenance is greater. Being higher, with less air to filter, you are subject to a greater amount of Gamma Rays, and probably other stuff that we don't know about. Now for the good stuff. If you are going the right direction you can pick up significant ground speed, which has to be balanced against the loss of time and fuel due to climbing In weather with imbedded Thunder bumpers, you can generally climb out of the crap and be able to see the cumulonimbus clouds. You feel like a "real airplane" If you fly in mountainous areas, or typically from high altitude airports, T/S charging will allow you to have a smaller engine to produce the necessary T.O. HP. Additionally it's Way cool! This information comes from my experience over the past 40 years, with 8 airplanes, 2 of which were turbo charged (Twin Comanche and Bellanca Viking). Being based in the Chicago area, I actually utilized the turbo advantage on a very limited basis. I have friends that live in the west that won't fly without it. If you occasionally fly high, the lack of charging in general, will only mean less airspeed and longer T.O runs. The landing distance (increased at high altitudes is the same for both configurations.) Your average mission will determine the benefits. Above all, no matter what you choose, know the limitations of your craft and fly safely within them. -------------------------------1150302534 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 6/14/2006 10:14:27 A.M. Central Standard Time,=20 kenpowell@comcast.net writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
Steve,
I think you are overestimating the power loss of converting over to=20 NA.  See this link: http://www.442.com/oldsfaq/o= fcrc.htm. =20 My understanding is that you will only suffer a 2.4 -4.2 HP loss if assumi= ng=20 the NA engine produced 200 HP (depending on a comparison of 9.4 rotor= s or=20 9.7 rotors as opposed to the 9.0 turbo rotors).  Compression ratio is= =20 much overated if you are not trying to make up for radical cam profiles in= =20 piston engines.
 
The decision to turbocharge/supercharge, or not really depends on one m= ain=20 thing. Like most decisions aeronautical, it depends on your purposed mission= for=20 the aircraft.
 
If your goal is to fly high and far most of the time, t/s charging is a= =20 great advantage. There are some drawbacks and those are mainly winds. When t= hey=20 are tail winds, they help you greatly. When they are headwinds, sometimes ev= en=20 with a 200+K plane, you are better off driving. As we all know, tail winds e= xist=20 only for other people. The other problem is the time, and fuel necessary to=20 climb to the high altitudes. The third is the need for O2, wonderful in theo= ry=20 and if you are up there, necessary, but a real pain in the a--nose in that y= ou=20 are breathing very dry air, in a dry environment and you dehydrate quickly.=20= Bad=20 on a long trip. Make sure that you bring lots of liquid, and a way to elimin= ate=20 it since all will not be eliminated through your sweat glands and lungs. Of=20 course if you are high enough the nasal canula is not approved so you must w= ear=20 a mask. Then you must take it off to drink, etc. Because of your altitude, y= ou=20 must plan your letdowns far in advance. you will be IFR and will for the mos= t=20 part be using High Altitude charts (or GPS direct). The OAT will be consider= ably=20 colder so that heater which was marginal now becomes useless. O2 is somewhat= =20 expensive and unless you have your own filling mechanism, available only at=20 specific locations. If you are using a lyco/conti saur, fuel flow and=20 maintenance is greater. Being higher, with less air to filter, you are=20 subject to a greater amount of Gamma Rays, and probably other stuff that we=20 don't know about.
 
Now for the good stuff. If you are going the right direction you can pi= ck=20 up significant ground speed, which has to be balanced against the loss of ti= me=20 and fuel due to climbing In weather with imbedded Thunder bumpers, you=20= can=20 generally climb out of the crap and be able to see the cumulonimbus clo= uds.=20 You feel like a "real airplane" If you fly in mountainous areas, or typicall= y=20 from high altitude airports, T/S charging will allow you to have a smaller=20 engine to produce the necessary T.O. HP. Additionally it's Way cool!
 
This information comes from my experience over the past 40 years, with=20= 8=20 airplanes, 2 of which were turbo charged (Twin Comanche and Bellanca Viking)= .=20 Being based in the Chicago area, I actually utilized the turbo advantage on=20= a=20 very limited basis. I have friends that live in the west that won't fly with= out=20 it. If you occasionally fly high, the lack of charging in general,  wil= l=20 only mean less airspeed and longer T.O runs. The landing distance (increased= at=20 high altitudes is the same for both configurations.)
 
Your average mission will determine the benefits. Above all, no matter=20= what=20 you choose, know the limitations of your craft and fly safely within them.
 
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