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From Jim Hergert,
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.
The Aero Cool the system is heavier. (Extra equipment-fan. Heavier 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 take weighing the two systems to know. 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? I just got back from my Concorde trip to the UK and I gained almost 10 lbs. Who cares about 2 or 3?
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. I know that if I look at the exhaust trails on my belly that there is NO evidence of turbulence. And when you have the AC off the fan is not moving air out of the tail. The NACA air inlet is the same stock one that is in every L4 vertical stab.and yes one of the Advantages of this kind of scoop is the MARKed reduction in drag when the air is NOT going in but spilling over in the slipstream. 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.
(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 wil see the difference and why they will probably require this on the turbines.
The 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 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 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 I would call it about even.
The Aero Cool system can take valuable baggage space.
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.
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?
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.
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.
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 cooling?
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 régimes.
Condenser size and weight should be compared, I'm not sure that they aren't about the same weight just different shape.
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.
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.
I guess that is where "LESS FILLING / TASTE GREAT" also applies here, I don't think I loose any speed..
No sacrifice of space in the aft baggage compartment.
Not an issue, see above.
Much less cost.
Should compare installed cost.
Much simpler installation.
Not by my book. Unless you mean no fan or wiring? But that scoop installation is not a simple chore.
And besides--doesn't that P-51 scoop looked neat!!!!
Your right, It looks great on a P-51.
Hey, I loved your discussion anyway. Let's fly.
BTW, you have never given a report of the MT prop with swept blades. And be objective.
Peace not flames; And that's the SCOOP;
Jim Hergert
N6XE, "An Sex Y" L4P
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