Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Fri, 17 Dec 2004 09:10:14 -0500 Message-ID: X-Original-Return-Path: Received: from imo-d03.mx.aol.com ([205.188.157.35] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 570886 for lml@lancaironline.net; Fri, 17 Dec 2004 07:46:41 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.157.35; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-d03.mx.aol.com (mail_out_v37_r3.8.) id q.1d2.2daf33d7 (3972) for ; Fri, 17 Dec 2004 07:46:06 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: <1d2.2daf33d7.2ef42f0e@aol.com> X-Original-Date: Fri, 17 Dec 2004 07:46:06 EST Subject: Re: [LML] Re: LNC2 Forward Facing Induction X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1103287566" X-Mailer: 9.0 Security Edition for Windows sub 1180 -------------------------------1103287566 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en =20 In a message dated 12/6/2004 9:21:37 P.M. Central Standard Time, =20 tthibaultsprint@earthlink.net writes: The performance improvement was very small. There was a small increase =20 in manifold pressure over the updraft without filter. I can make 19.5"=20 MAP at 12.5K feet. At best, my TAS increased 5 knots. Quite an expense=20 and effort for so little of a performance gain. Tom, =20 You got me thinking about whether or not you are finished with the =20 "experimental" mods, yet. Then I looked at some material Chris Zavatson ha= d provided=20 - a chart showing a comparison between his old airbox and the improvements=20 gained from his new ram air charted against altitude derived static pressur= e. =20 I went up to 12,500 and at WOT, 2500 RPM, level flight at 163 IAS (193 TAS)= ,=20 I saw a 20.2" MAP against a 18.66" standard day altitude derived static =20 pressure. BUT, it wasn't a standard day since the baro setting was 30.55 a= nd the=20 OAT was -8C (17F) at altitude. This yielded a palt of 11960 and a dalt of=20 11550 (about 19.4") - maybe. =20 =20 Hmmmmm.... How can we compare our ram systems? The "Aerodynamics of Naval= =20 Aviators" pub says you can only make comparisons at the same density=20 altitude. But, there are a few problems with a few things. To wit: =20 1. The method for computing the true static pressure is troublesome since i= t=20 is affected by temperature, humidity, the mean temperature at the various =20 altitudes below you, baro setting, etc. The temperature is also affected b= y=20 compressibility since we are going faster than 150 Kts. Of course, convert= ing=20 this all to "standard day" readings. Note, however, that there is a rule o= f=20 thumb that says for every 10 degrees temperature difference from standard=20 there is a 4% change in altitude. I didn't get the TAT (True Air Temp), bu= t it=20 was probably a few degrees cooler, say -11C, which would then only be a=20 difference of -1C from the standard temp for 12,500 MSL. =20 2. Remember that the pure rise in ram pressure is approximately (in " HG): 100 KIAS - .5" 150 KIAS - 1.1" 200 KIAS - 2" After all, that is how our pitot/static airspeed indicator works. So, at m= y=20 KIAS of 163, I could only expect a max of 1.2" rise. What is it exactly?=20 Who knows? =20 3. The measurement of MAP: Remember that MAP is Manifold Absolute Pressure= =20 - actually, a measurement of vacuum at anything less than WOT. Everybody's= =20 MAP instrument may be a bit different - kinda like body temperature. With=20= the=20 engine off, my readout is usually about 29.6 at my airport elevation of 700= =20 MSL (standard day should be about 29.2). Of course, on the test day I didn= 't=20 look at that readout on my VM EPI 800 system. My buddy's VM 1000 said 28.6.= =20 So, one must also know the MAP instrument offset. =20 4. Assuming all things being equal (like don't drain off anymore air), the =20 pressure was about .6" Hg (about 8" H2O) higher than static in the upper =20 cowling cooling plenum. Hmmmmm.... Next time I will re-plumb my pitot driv= en=20 injector air system and see what it says.=20 =20 Where does that lead us? See you at the next Air Venture Cup Race. Now=20 that's the way to compare things. =20 Consider this: =20 =20 RAM-Air STC Now Available For Grumman AA-5 Traveler And AA-5A Cheetah Alt Air Without The Filter (http://www.aero-news.net/##) Approach Aviation Development Thursday said=20 it has received FAA STC SA00206BO for an Alternate Air system for all Grumm= an=20 AA-5 Traveler and AA-A Cheetahs.=20 The new =E2=80=9CRAM-Air=E2=80=9D Alternate Air System is designed to provi= de an alternate=20 source of induction air to the engine without the restriction of the standa= rd=20 induction air filter. This system allows the pilot to bypass the induction=20 air filter in-flight without the reduction in available engine power caused= by=20 resorting to carburetor heat. A cable control in the cockpit opens/closes a= =20 valve into the airbox that supplies unfiltered, high-pressure air from the=20 available air in front of the forward engine baffling.=20 The high-pressure location of the inlet provides a source of "Ram-Air" whic= h=20 has been tested to increase manifold pressure by approximately 1/2+" Hg.=20 This equates to 4-5 HP more horsepower at altitudes where normally aspirate= d=20 aircraft engines typically produce 75% power or less. The system also incre= ases=20 the service ceiling and effectively reduces the aircraft=E2=80=99s pressure= altitude=20 by about 750 feet MSL.=20 "The =E2=80=9CRAM-Air=E2=80=9D Alternate Air System is an outstanding and e= conomical=20 performance addition to the Grumman Traveler and Cheetah." said Jeff Simon,= =20 President of Approach Aviation Development, Inc. "Aircraft induction filter= s are=20 always a compromise of engine protection vs. performance. This system prese= rves=20 the integrity of the filter on the ground, while allowing the pilot to take= =20 advantage of the increased power naturally available in flight.=E2=80=9D=20 The =E2=80=9CRAM-Air=E2=80=9D Alternate Air System, complete with all neces= sary hardware,=20 is available at the introductory price of $750. Installation is very=20 straightforward with a typical install time of approximately 4-6 hours.=20 FMI: _www.ApproachAviation.com_ (http://www.approachaviation.com/) =20 From Aero-news.net=20 Scott Krueger AKA Grayhawk N92EX IO320 Aurora, IL (KARR) Some Assembly Required=20 Using Common Hand Tools=20 And the Air We Breathe. -------------------------------1103287566 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en
In a message dated 12/6/2004 9:21:37 P.M. Central Standard Time,=20 tthibaultsprint@earthlink.net writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The=20 performance improvement was very small.  There was a small increase=20
in manifold pressure over the updraft without filter.  I can make= =20 19.5"
MAP at 12.5K feet.  At best, my TAS increased 5 knots. = ;=20 Quite an expense
and effort for so little of a performance=20 gain.
Tom,
 
You got me thinking about whether or not you are finished with the=20 "experimental" mods, yet.  Then I looked at some material Chris Zavatso= n=20 had provided - a chart showing a comparison between his old airbox and the=20 improvements gained from his new ram air charted against altitude derived st= atic=20 pressure.
 
I went up to 12,500 and at WOT, 2500 RPM, level flight at 163 IAS (193=20 TAS), I saw a 20.2" MAP against a 18.66" standard day altitude derived stati= c=20 pressure.  BUT, it wasn't a standard day since the baro=20 setting was 30.55 and the OAT was -8C (17F) at altitude. = ;=20 This yielded a palt of 11960 and a dalt of 11550 (about 19.4") - maybe. = ;=20
 
Hmmmmm....  How can we compare our ram systems?  The=20 "Aerodynamics of Naval Aviators" pub says you can only make comparisons at t= he=20 same density altitude.  But, there are a few problems with a few=20 things.  To wit:
 
1. The method for computing the true static pressure is troublesome sin= ce=20 it is affected by temperature, humidity, the mean temperature at the various= =20 altitudes below you, baro setting, etc.  The temperature is also affect= ed=20 by compressibility since we are going faster than 150 Kts.  Of course,=20 converting this all to "standard day" readings.  Note, however, that th= ere=20 is a rule of thumb that says for every 10 degrees temperature difference fro= m=20 standard there is a 4% change in altitude.  I didn't get the TAT (True=20= Air=20 Temp), but it was probably a few degrees cooler, say -11C, which would then=20= only=20 be a difference of -1C from the standard temp for 12,500 MSL.
 
2. Remember that the pure rise in ram pressure is approximately (in "=20 HG):
100 KIAS - .5"
150 KIAS - 1.1"
200 KIAS - 2"
After all, that is how our pitot/static airspeed indicator works. = So,=20 at my KIAS of 163, I could only expect a max of 1.2" rise.  What is it=20 exactly? Who knows?
 
3. The measurement of MAP:  Remember that MAP is Manifold Absolute= =20 Pressure - actually, a measurement of vacuum at anything less than WOT. = ;=20 Everybody's MAP instrument may be a bit different - kinda like body=20 temperature.  With the engine off, my readout is usually about 29.6 at=20= my=20 airport elevation of 700 MSL (standard day should be about 29.2). =20 Of course, on the test day I didn't look at that readout on my VM=20= EPI=20 800 system. My buddy's VM 1000 said 28.6.  So, one must also know=20= the=20 MAP instrument offset.
 
4. Assuming all things being equal (like don't drain off anymore air),=20= the=20 pressure was about .6" Hg (about 8" H2O) higher than static in the uppe= r=20 cowling cooling plenum.  Hmmmmm.... Next time I will re-plumb my pitot=20 driven injector air system and see what it says. 
 
Where does that lead us?  See you at the next Air Venture Cup=20 Race.  Now that's the way to compare things.
 
Consider this:
 

RAM-Air STC Now Available For Gru= mman=20 AA-5 Traveler And AA-5A Cheetah

Alt=20 Air Without The Filter

= Approach=20 Aviation Development Thursday said it has received FAA STC SA00206BO for an=20 Alternate Air system for all Grumman AA-5 Traveler and AA-A=20 Cheetahs.

The new= =20 =E2=80=9CRAM-Air=E2=80=9D Alternate Air System is designed to provide an alt= ernate source of=20 induction air to the engine without the restriction of the standard inductio= n=20 air filter. This system allows the pilot to bypass the induction air filter=20 in-flight without the reduction in available engine power caused by resortin= g to=20 carburetor heat. A cable control in the cockpit opens/closes a valve into th= e=20 airbox that supplies unfiltered, high-pressure air from the available air in= =20 front of the forward engine baffling.

The=20 high-pressure location of the inlet provides a source of "Ram-Air" which has= =20 been tested to increase manifold pressure by approximately 1/2+" Hg. This=20 equates to 4-5 HP more horsepower at altitudes where normally aspirated airc= raft=20 engines typically produce 75% power or less. The system also increases the=20 service ceiling and effectively reduces the aircraft=E2=80=99s pressure alti= tude by=20 about 750 feet MSL.

"The=20 =E2=80=9CRAM-Air=E2=80=9D Alternate Air System is an outstanding and economi= cal performance=20 addition to the Grumman Traveler and Cheetah." said Jeff Simon, President of= =20 Approach Aviation Development, Inc. "Aircraft induction filters are always a= =20 compromise of engine protection vs. performance. This system preserves the=20 integrity of the filter on the ground, while allowing the pilot to take=20 advantage of the increased power naturally available in=20 flight.=E2=80=9D

The=20= =E2=80=9CRAM-Air=E2=80=9D=20 Alternate Air System, complete with all necessary hardware, is available at=20= the=20 introductory price of $750. Installation is very straightforward with a typi= cal=20 install time of approximately 4-6 hours.

FMI: www.ApproachAviation.com<= /o:p>

 =

From Aero-news.net

 

Scott Krueger AKA Grayhawk
N92EX IO320= Aurora,=20 IL (KARR)

Some Assembly Required
Using Common Hand Tools

And the Air We=20 Breathe.

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