Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Tue, 19 Apr 2005 15:08:52 -0400 Message-ID: X-Original-Return-Path: Received: from imo-m21.mx.aol.com ([64.12.137.2] verified) by logan.com (CommuniGate Pro SMTP 4.3c3) with ESMTP id 883370 for lml@lancaironline.net; Tue, 19 Apr 2005 10:07:27 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.2; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-m21.mx.aol.com (mail_out_v38.7.) id q.1d5.3a60d6f2 (3866) for ; Tue, 19 Apr 2005 10:06:37 -0400 (EDT) From: Sky2high@aol.com X-Original-Message-ID: <1d5.3a60d6f2.2f966a6d@aol.com> X-Original-Date: Tue, 19 Apr 2005 10:06:37 EDT Subject: Re: [LML] Re: max range vs. max endurance X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1113919597" X-Mailer: 9.0 Security Edition for Windows sub 5000 -------------------------------1113919597 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 4/19/2005 7:43:22 A.M. Central Standard Time, walter@advancedpilot.com writes: I always thought max range was calculated at L/D airspeed. I don't think, historically, it's been done at 65% power. Besides, max endurance has nothing to do with distance, it has to do with *time* aloft. Max range is a no-wind DISTANCE, while max endurance is a max time. I may be wrong, but that's how I've always thought of those terms. Thoughts? Walter On Apr 19, 2005, at 7:06 AM, Matt Hapgood wrote: Can someone explain to me if this makes sense (Max endurance has greater range than max range)? Conceptually this doesn't make sense to me... The data is from Lancair Production website for the 400. Cruise Data Max Power Speed (FL180) . . . . . . . . . . 230 KTAS (265 mph) Max Recommended Cruise Power Speed (FL25) . 235 KTAS (270 mph) Max Range (65% Power, FL180, 200 KTAS). . . 1071 Nautical Miles* Max Endurance. . . . . . . . . . . . . . .. 1320 Nautical Miles* Walter is correct. Using "Aerodynamics for Naval Aviators" as a reference for reciprocating engines and the Navy as a respectful organization that might find it useful to teach its' pilots to make use of max range and endurance so as to eliminate flights ending up in the sea, the following info was found to be pertinent. Max Range is indeed to be flown at Max L/D and must take into account the changing weight as fuel is burned. Even more important in airplanes whose total weight is significantly influenced by fuel weight (like our wee lawn darts). At some constant altitude, a 10% increase in weight would require a 5% increase in velocity (IAS?), 15% increase in power and a 9% decrease in specific range( NM/lb fuel). If compressibility effects are negligible, range variation related to altitude is a function of prop/engine performance (except for the fuel consumed in climb). However, turbocharging may improve range at higher altitude. Anyway, Lancair just gave a range number for a specific power setting, altitude and speed (implying weight). Also, endurance is defined by time aloft. The time that the airplane can be held in level flight at the lowest fuel flow. Generally, the velocity would be around 75% of the speed for max range. Calculations indicate that the lowest practical flight altitude would yield the max endurance. Any distance calculated from the speed would be greatly influenced by the winds since so much time would be spent aloft. I am sure Lancair just did a calculation for the distance one could cover at some max endurance speed and reduced fuel flow. Matt, note that max range and max endurance were "starred", and that text was: * Includes climb, descent and 45 minute reserves Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) Fair and Balanced Opinions at No Charge! Metaphysical Monologues used at your own Risk. -------------------------------1113919597 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 4/19/2005 7:43:22 A.M. Central Standard Time,=20 walter@advancedpilot.com writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I always=20 thought max range was calculated at L/D airspeed.  I don't
think,= =20 historically, it's been done at 65% power.  Besides, max
enduranc= e=20 has nothing to do with distance, it has to do with *time*
aloft. = Max=20 range is a no-wind DISTANCE, while max endurance is a max
time. =20= I=20 may be wrong, but that's how I've always thought of those=20
terms.

Thoughts?

Walter


On Apr 19, 2005, at 7= :06=20 AM, Matt Hapgood wrote:



Can someone explain to me if this m= akes=20 sense (Max endurance has greater
range than max range)?  Conceptua= lly=20 this doesn't make sense to me...

The data is from Lancair Productio= n=20 website for the 400.

Cruise Data
  Max Power Speed (FL180)=20= . .=20 . . . . . . . .  230 KTAS  (265 mph)
  Max Recommended=20 Cruise Power Speed (FL25) .  235 KTAS  (270 mph)
  Max R= ange=20 (65% Power, FL180, 200 KTAS). . . 1071  Nautical Miles*
  Max= =20 Endurance. . . . . . . . . . . . . . .. 1320  Nautical=20 Miles*

 
Walter is correct.  Using "Aerodynamics for Naval Aviators" as a=20 reference for reciprocating engines and the Navy as a respectful=20 organization that might find it useful to teach its' pilots to make use of m= ax=20 range and endurance so as to eliminate flights ending up in the sea, the=20 following info was found to be pertinent. 
 
Max Range is indeed to be flown at Max L/D and must take into account t= he=20 changing weight as fuel is burned.  Even more important in airplanes wh= ose=20 total weight is significantly influenced by fuel weight (like our wee lawn=20 darts). At some constant altitude, a 10% increase in weight would require a=20= 5%=20 increase in velocity (IAS?), 15% increase in power and a 9% decrease in spec= ific=20 range( NM/lb fuel).  If compressibility effects are negligible, range=20 variation related to altitude is a function of prop/engine performance (exce= pt=20 for the fuel consumed in climb). However, turbocharging may improve range at= =20 higher altitude.  Anyway, Lancair just gave a range number for a specif= ic=20 power setting, altitude and speed (implying weight).
 
Also, endurance is defined by time aloft.  The time that the airpl= ane=20 can be held in level flight at the lowest fuel flow.  Generally,=20 the velocity would be around 75% of the speed for max range. =20 Calculations indicate that the lowest practical flight altitude would yield=20= the=20 max endurance.  Any distance calculated from the speed would be greatly= =20 influenced by the winds since so much time would be spent aloft.  I am=20= sure=20 Lancair just did a calculation for the distance one could cover at some max=20 endurance speed and reduced fuel flow. 
 
Matt, note that max range and max endurance were "starred", and that te= xt=20 was:
 
* Includes climb, descent and 45 minute reserves
 
 
Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL (KARR)

Fai= r=20 and Balanced Opinions at No Charge!
Metaphysical Monologues used at your=20= own=20 Risk.

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