Return-Path: Sender: (Marvin Kaye) To: lml Date: Mon, 16 Jun 2003 11:01:22 -0400 Message-ID: X-Original-Return-Path: Received: from ms-smtp-04.tampabay.rr.com ([65.32.1.35] verified) by logan.com (CommuniGate Pro SMTP 4.1b8) with ESMTP id 2431037 for lml@lancaironline.net; Mon, 16 Jun 2003 10:57:11 -0400 Received: from 34025820001 (106.146.33.65.cfl.rr.com [65.33.146.106]) by ms-smtp-04.tampabay.rr.com (8.12.8p1/8.12.5) with SMTP id h5GEv8jo020811 for ; Mon, 16 Jun 2003 10:57:09 -0400 (EDT) X-Original-Message-ID: <005401c33417$b1f39a50$6a922141@34025820001> From: "Charlie Kohler" X-Original-To: "LancairList" Subject: A/C X-Original-Date: Mon, 16 Jun 2003 10:58:06 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0051_01C333F6.2AB98AC0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 This is a multi-part message in MIME format. ------=_NextPart_000_0051_01C333F6.2AB98AC0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Jim, First let me welcome Charlie back, I missed him for a while. I very much = appreciate your inputs and am very happy that your AC works that good. = In no way do I feel that either system is better than the other rather = that we all have two choices. However, I would like to respond to a few = things that Charlie brought up that are not completely true. Thanks for these good comments, sure is better than getting flamed. Not = completely true? Those are the things I'm looking to square away. -------------------------------------------------------------------------= ---------------------------------=20 The Aero Cool the system is heavier. (Extra equipment-fan. Heavier = wiring-fan. Heavier hoses- to run further aft.)=20 The fan weight is probably less that 2 or 3 lbs different if at all. It = would take weighing the two systems to know.=20 You are right, The only way we can determine the truth here is to weigh = both systems and make sure the inventory is correct. Later , you = mentioned that the scoop would be equal to mounting for the condenser. = The scoop is made out of carbon and is very light. The one Installation = I saw of the Aero Cool looked much heavier. And the items above in = parentheses are undoubtedly heavier in the Aero-Cool system. -------------------------------------------------------------------------= ---------------------------------- The scoop and all it's attaching cloth, resin, primer and paint and you = have to run the lines from the armrest area to the center of the floor = taking up space there. How do you cover them? Does that weigh anything?=20 The scoop is made out of carbon and is very light. No covers are needed. = Air conditioning hoses go underneath the aft side of the main spar = covers. Alongside the main fuel lines. The dryer is located on the = sidewall.=20 -------------------------------------------------------------------------= ---------------------------------- I just got back from my Concorde trip to the UK and I gained almost 10 = lbs. Who cares about 2 or 3? A pound here , a pound there, adds up. I think it's a trade-off. I have = the Ryan 9900 BX. It's a very heavy unit. I think I would rather have it = at the expense of most anything else.=20 -------------------------------------------------------------------------= ---------------------------------- The Aero Cool system has drag by cutting holes in the fuselage and = blowing out hot air. Perhaps more drag than a scoop. This is pure guessing. Yes, but educated (from experience) guessing.=20 I first flew the Lancair at Santa Paula Airport , with Neil Perks in = 1991. The airplane did not have gear doors over the main gear. When they = installed those doors, The airspeed increased approximately 15 knots. Do you recall , the Orinda , powered Tigris? I recall a conversation = with Don G. in which he said that during a test flight with the radiator = exhausting down the side of the fuselage that he felt it was trying to = go sideways. The speeds estimated never materialized. I wonder why? I recall having a door come open on an Aztec many years ago and nearly = lost control.=20 -------------------------------------------------------------------------= --------------------------------- air is NOT going in but spilling over in the slipstream. I would maintain that the air is spilling out of the NACA scoop and not = entering if you have the fan turned off.=20 -------------------------------------------------------------------------= ------------------------------ How does your belly scoop handle the drag when it is not needed for = cooling? If air is going thru the condenser then it is big drag. Possibly, but the term "big" would indicate a large loss of airspeed , = and that is not the case. And the KISS principle applies. No doors. No = levers. No cranks. No motors. -------------------------------------------------------------------------= ------------------------------ (Questions arise as to structural strength. *) Strength is probably a slight bit less but it is in the big part of the = fuselage not the small area in front of the tail. That is where the L4 = is weak. In fact the factory is coming out with a tail stiffing mod. = that adds about 2 inches to the leading edge of the vertical stab. and a = much bigger dorsel fin going forward to help strengthen the tail = torsorsonal resistance. It looks much better too. Just do a vertical Hit = on the tip of you Horz stab. and watch the shake. Then do this on the = Tandem, you will see the difference and why they will probably require = this on the turbines. I worked two years in the engineering department of International = Harvester motor truck engineering division, in the stress lab. I = performed photo stress, stress coat, and strain gauge analysis of truck = frames , front end parts etc. etc.. The term "slight bit less" would have made my boss go ballistic. One of the reason I chose the Lancair, was the stress analysis--and = flutter analysis. We are modifying these airplanes to the point where = these original analysis are no longer valid. Band-Aids are being put in = places where a new analysis should be done. Your hitting the tail to = excite the empennage is just the warning flag.=20 -------------------------------------------------------------------------= --------------------------------=20 Aero Cool system requires much more electrical service.=20 I don't see this, but we would have to put a load meter on to find out. = When I idle at 800 rpm with the AC full on I do get a low voltage light = and my SFS reads 12.9 volts. Then after take off with everything on I = get a Low Voltage and Standby Alt light when I put the gear up. That = Hyd. pump draws a lot. BTW, I have a 65 amp alt. on 12V and full UPS = stack, 3 screen SFS, TCAD, Storm Scope, and TruTrak 3 servo AP. All on = but not engaged at that time. In other words, I'm drawing a few amps = that others may not. The only electrical load that would be in excess of the Airflow system = is that of the condenser cooling fan.=20 -------------------------------------------------------------------------= ------------------------------ The Aero Cool system is much more complex to install.=20 I'm not sure how easy it is to install the scoop on the bottom and paint = but I would call it about even. If I'm correct, I understand that in the Aero Cool system, the elevator = pressure compensators are removed. Then a modification to the elevator = pressure boots to the direct system. Installing the condenser box, = cutting holes, installing scoops, moving electronic equipment , etc. = etc. Whereas, on the airflow system the scoop is glued directly to the = fuselage by standard surface preparation and clicos.=20 -------------------------------------------------------------------------= --------------------------------------- Mine doesn't take ANY room out of the baggage compartment, and I still = could have put in a SKI tube. The condenser is below the baggage floor = level and behind the rear baggage bulkhead. The TCAD, Stormscope, and = AHRS would be the ones likely to interfere. I give you this one. -------------------------------------------------------------------------= ------------------------------------------- The Aero Cool system moves the center of gravity aft. Will you be able = to carry backseat passengers in that rare event they're needed?=20 I recently had 4 on board, Mike Custard being one, and 55 gals. Took off = from Sedona, AZ. 4800 ft Alt. with AC on and flew over the Grand Canyon = and made it back. Nice ride. However, I will give Charlie one here that = I am in the aft CG area. Just weighed it with full 108 gal. fuel and two = 200 pounders in the front and was at 92.4% vs a 94% aft limit. Must = watch the back seat load. Sure glad you "made it back." If I had one more figure, gross weight, we = we could see where the CG curve is. Using MT prop, I'm afraid I would be = out the aft limit with 114 gal. of fuel , and a hefty copilot.=20 -------------------------------------------------------------------------= -------------------------------------- The Aero Cool system cost more to purchase--costs more to install. I use to worry about money now I worry about have enough time to spend = it. I don't know the prices so that should be taken into account. I sure would like to work for you! -------------------------------------------------------------------------= --------------------------------------=20 The Airflow systems unit needs no fan for the condenser.=20 How long can you be taxing or on hold on the ground before it shows less = cooling?=20 Actually , I don't know of any restriction or time that would make the = Airflow system be less effective. If it works 10 minutes after start up, = it'll work good 30 minutes after start up. -------------------------------------------------------------------------= ------------------------------------------ It works well on the ground (the propeller provides the cooling airflow = over the condenser.) Therefore, it's lighter. Condenser can be smaller because of the = adequate Airflow in all r=E9gimes.=20 Condenser size and weight should be compared, I'm not sure that they = aren't about the same weight just different shape. As with any heat exchanger, you can increase area to get better = cooling/heating. Have you ever heard of the discussion to increase the = size? -------------------------------------------------------------------------= ---------------------------------------------- Condenser is located outside the hull, and the heat associated in a = closed contained environment, therefore requiring less Airflow to cool = the condensate. This is a guess. Mine is outside of the pressure vessel also. My = complete fuselage is a heat sink in the rear. And cooling drag is bad = from other areas, like the cowl seams and the NOSE gear doors. Also, = where does all that air go that we pump into the cabin? An airplane is a = Bunch of compromises flying in close formation, ya know. I would debate , the wisdom of using the empennage as a "heat sink." I = agree that cabin pressurization air is exhausted into the wheel well = area and spills out into the airstream. For what effect I do not know. And = yes , we compromise all over the place. -------------------------------------------------------------------------= -------------------------------------------- Small loss in airspeed, that perhaps, may be the same as, or less than = the Aero Cool system, due to less weight, and no holes in the fuselage = providing turbulent Airflow over the fuselage and tail surfaces.=20 I guess that is where "LESS FILLING / TASTE GREAT" also applies here, I = don't think I loose any speed.. Very True! I only wanted to raise the awareness that there IS drag from = the internal system. How to quantify this?? I do not think we have the = ability to do such tests with any great accuracy. -------------------------------------------------------------------------= ------------------------------------------- And besides--doesn't that P-51 scoop looked neat!!!!=20 Your right, It looks great on a P-51. Yes sir, Just like Winglets look good on a Learjet.=20 -------------------------------------------------------------------------= ----------------------------------------- Hey, I loved your discussion anyway. Let's fly. ME TOO!!! -------------------------------------------------------------------------= --------------------------------------=20 BTW, you have never given a report of the MT prop with swept blades. And = be objective.=20 The large blade MTV , prop did not meet our expectations. This is a = discussion that would take several more hours. Peace not flames; And that's the SCOOP; Jim Hergert N6XE, "An Sex Y" L4P -------------------------------------------------------------------------= Charlie K. ------=_NextPart_000_0051_01C333F6.2AB98AC0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Hi Jim,

First let me welcome Charlie back, I missed him for a while. I very = much=20 appreciate your inputs and am very happy that your AC works that good. = In no way=20 do I feel that either system is better than the other rather that we all = have=20 two choices. However, I would like to respond to a few things that = Charlie=20 brought up that are not completely true.

Thanks for these good comments, sure is better than getting = flamed.=20 Not completely true? Those are the things I'm looking to square=20 away.

----------------------------------------------------------------------= ------------------------------------=20

The Aero Cool the system is heavier. (Extra equipment-fan. Heavier=20 wiring-fan. Heavier hoses- to run further aft.)

The fan weight is probably less that 2 or 3 lbs different if at all. = It would=20 take weighing the two systems to know.

You are right, The only way we can determine the truth here = is to=20 weigh both systems and make sure the inventory is correct. Later , you = mentioned=20 that the scoop would be equal to mounting for the condenser. The scoop = is made=20 out of carbon and is very light. The one Installation I saw of the Aero = Cool=20 looked much heavier. And the items above in parentheses are undoubtedly = heavier=20 in the Aero-Cool system.

----------------------------------------------------------------------= -------------------------------------

The scoop and all it's attaching cloth, resin, primer and paint and = you have=20 to run the lines from the armrest area to the center of the floor taking = up=20 space there. How do you cover them? Does that weigh anything?

The scoop is made out of carbon and is very light. No covers = are=20 needed. Air conditioning hoses go underneath the aft side of the = main spar=20 covers. Alongside the main fuel lines. The dryer is located on the = sidewall.=20

----------------------------------------------------------------------= -------------------------------------

I just got back from my Concorde trip to the UK and I gained almost = 10 lbs.=20 Who cares about 2 or 3?

A pound here , a pound there, adds up. I think it's a = trade-off. I=20 have the Ryan 9900 BX. It's a very heavy unit. I think I would rather = have it at=20 the expense of most anything else.

----------------------------------------------------------------------= -------------------------------------

The Aero Cool system has drag by cutting holes in the fuselage and = blowing=20 out hot air. Perhaps more drag than a scoop.

This is pure guessing.

Yes, but educated (from experience) = guessing.

I first flew the Lancair at Santa Paula Airport , with Neil = Perks in=20 1991. The airplane did not have gear doors over the main gear. When they = installed those doors, The airspeed increased approximately 15=20 knots.

Do you recall , the Orinda , powered Tigris? I recall a = conversation=20 with Don G. in which he said that during a test flight with the radiator = exhausting down the side of the fuselage that he felt it was trying to = go=20 sideways. The speeds estimated never materialized. I wonder = why?

I recall having a door come open on an Aztec many years ago = and=20 nearly lost control.

---------------------------------------------------------------= -------------------------------------------

air is NOT going in but spilling over in the slipstream.

I would maintain that the air is spilling out of the NACA = scoop and=20 not entering if you have the fan turned off.

----------------------------------------------------------------------= ---------------------------------

How does your belly scoop handle the drag when it is not needed for = cooling?=20 If air is going thru the condenser then it is big drag.

Possibly, but the term "big" would indicate a large loss of = airspeed=20 , and that is not the case. And the KISS principle applies. No doors. No = levers.=20 No cranks. No motors.

----------------------------------------------------------------------= ---------------------------------

(Questions arise as to structural strength. *)

Strength is probably a slight bit less but it is in the big part of = the=20 fuselage not the small area in front of the tail. That is where the L4 = is weak.=20 In fact the factory is coming out with a tail stiffing mod. that adds = about 2=20 inches to the leading edge of the vertical stab. and a much bigger = dorsel fin=20 going forward to help strengthen the tail torsorsonal resistance. It = looks much=20 better too. Just do a vertical Hit on the tip of you Horz stab. and = watch the=20 shake. Then do this on the Tandem, you will see the difference and why = they will=20 probably require this on the turbines.

I worked two years in the engineering department of = International=20 Harvester motor truck engineering division, in the stress lab. I = performed photo=20 stress, stress coat, and strain gauge analysis of truck frames , front = end parts=20 etc. etc..

The term "slight bit less" would have made my boss go=20 ballistic.

One of the reason I chose the Lancair, was the stress = analysis--and=20 flutter analysis. We are modifying these airplanes to the point where = these=20 original analysis are no longer valid. Band-Aids are being put in places = where a=20 new analysis should be done. Your hitting the tail to excite the = empennage is=20 just the warning flag.

----------------------------------------------------------------------= -----------------------------------=20

Aero Cool system requires much more electrical service.

I don't see this, but we would have to put a load meter on to find = out. When=20 I idle at 800 rpm with the AC full on I do get a low voltage light and = my SFS=20 reads 12.9 volts. Then after take off with everything on I get a Low = Voltage and=20 Standby Alt light when I put the gear up. That Hyd. pump draws a lot. = BTW, I=20 have a 65 amp alt. on 12V and full UPS stack, 3 screen SFS, TCAD, Storm = Scope,=20 and TruTrak 3 servo AP. All on but not engaged at that time. In other = words, I'm=20 drawing a few amps that others may not.

The only electrical load that would be in excess of the = Airflow=20 system is that of the condenser cooling fan.

----------------------------------------------------------------------= ---------------------------------

The Aero Cool system is much more complex to install.

I'm not sure how easy it is to install the scoop on the bottom and = paint but=20 I would call it about even.

If I'm correct, I understand that in the Aero Cool system, = the=20 elevator pressure compensators are removed. Then a modification to the = elevator=20 pressure boots to the direct system. Installing the condenser box, = cutting=20 holes, installing scoops, moving electronic equipment , etc. = etc.

Whereas, on the airflow system the scoop is glued directly to = the=20 fuselage by standard surface preparation and clicos. =

----------------------------------------------------------------------= ------------------------------------------

Mine doesn't take ANY room out of the baggage compartment, and I = still could=20 have put in a SKI tube. The condenser is below the baggage floor level = and=20 behind the rear baggage bulkhead. The TCAD, Stormscope, and AHRS would = be the=20 ones likely to interfere.

I give you this one.

----------------------------------------------------------------------= ----------------------------------------------

The Aero Cool system moves the center of gravity aft. Will you be = able to=20 carry backseat passengers in that rare event they're needed?

I recently had 4 on board, Mike Custard being one, and 55 gals. Took = off from=20 Sedona, AZ. 4800 ft Alt. with AC on and flew over the Grand Canyon and = made it=20 back. Nice ride. However, I will give Charlie one here that I am in the = aft CG=20 area. Just weighed it with full 108 gal. fuel and two 200 pounders in = the front=20 and was at 92.4% vs a 94% aft limit. Must watch the back seat = load.

Sure glad you "made it back." If I had one more figure, gross = weight,=20 we we could see where the CG curve is. Using MT prop, I'm afraid I would = be out=20 the aft limit with 114 gal. of fuel , and a hefty copilot.=20

----------------------------------------------------------------------= -----------------------------------------

The Aero Cool system cost more to purchase--costs more to = install.

I use to worry about money now I worry about have enough time to = spend it. I=20 don't know the prices so that should be taken into account.

I sure would like to work for you!

----------------------------------------------------------------------= -----------------------------------------=20

The Airflow systems unit needs no fan for the condenser.

How long can you be taxing or on hold on the ground before it shows = less=20 cooling?

Actually , I don't know of any restriction or time that would = make=20 the Airflow system be less effective. If it works 10 minutes after start = up,=20 it'll work good 30 minutes after start up.

----------------------------------------------------------------------= ---------------------------------------------

It works well on the ground (the propeller provides the cooling = airflow over=20 the condenser.)

Therefore, it's lighter. Condenser can be smaller because of the = adequate=20 Airflow in all r=E9gimes.

Condenser size and weight should be compared, I'm not sure that they = aren't=20 about the same weight just different shape.

As with any heat exchanger, you can increase area to get = better=20 cooling/heating. Have you ever heard of the discussion to increase the=20 size?

----------------------------------------------------------------------= -------------------------------------------------

Condenser is located outside = the hull,=20 and the heat associated in a closed contained environment, therefore = requiring=20 less Airflow to cool the condensate.

This is a guess. Mine is outside of the pressure vessel also. My = complete=20 fuselage is a heat sink in the rear. And cooling drag is bad from other = areas,=20 like the cowl seams and the NOSE gear doors. Also, where does all that = air go=20 that we pump into the cabin? An airplane is a Bunch of compromises = flying in=20 close formation, ya know.

I would debate , the wisdom of using the empennage as a "heat = sink."=20 I agree that cabin pressurization air is exhausted into the wheel well=20 area

and spills out into the airstream. For what effect I do not = know. And=20 yes , we compromise all over the place.

----------------------------------------------------------------------= -----------------------------------------------

Small loss in airspeed, that perhaps, may be the same as, or = less than=20 the Aero Cool system, due to less weight, and no holes in the fuselage = providing=20 turbulent Airflow over the fuselage and tail surfaces.

I guess that is where "LESS FILLING / TASTE GREAT" also applies here, = I don't=20 think I loose any speed..

Very True! I only wanted to raise the awareness that there IS = drag=20 from the internal system. How to quantify this?? I do not think we have = the=20 ability to do such tests with any great = accuracy.

----------------------------------------------------------------------= ----------------------------------------------

And besides--doesn't that P-51 scoop looked neat!!!!

Your right, It looks great on a P-51.

Yes sir, Just like Winglets look good on a Learjet.=20

----------------------------------------------------------------------= --------------------------------------------

Hey, I loved your discussion anyway. Let's fly.

ME TOO!!!

----------------------------------------------------------------------= -----------------------------------------=20

BTW, you have never given a report of the MT prop with swept blades. = And be=20 objective.

The large blade MTV , prop did not meet our expectations. = This is a=20 discussion that would take several more hours.

Peace not flames; And that's the SCOOP;

Jim Hergert

N6XE, "An Sex Y" L4P

--------------------------------------------------------------= -----------

Charlie=20 K.

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