Cruisair "Ceiling "

[blimpy]

Now that the engine is in fine fettle, I decided to take her up as high as she would go,
and see what I got. Since 12,000 is sometimes warranted for crossing the Sierras safely...
I needed to see how long that was going to take, and what the ship would be like when I got there.

Short answer is she's not going higher with out a LONG wait, and clearly flying at a pretty high angle of attack.

Here are the results as I remember them.
------I was getting kinda dizzy and dopey and had to use the disposable oxygen , as I spent a long time above 10,000 feet ! ----

150 Hp Aeromatic Prop more or less set for sea level.

Take off fuel.. full to top ( more than 40 gal)
time to climb 1:23
overall average climb rate 169 FPM

couple of excursions to cruise speed to lean.. which became critical to climbing at all.
( which put a vernier mixture control on my to buy list )

Max Altitude 14,100 indicated - climb rate down to 50 FPM.. not really enough to read on the VSI
Calculated DA approx. 15,440 Ft.
OAT at 14,100 30 degrees F minus 1.1 degrees C

RPM 2100 Manifold Pressure 17.5 inches ( maybe 17)

Indicated Airspeed 90-92 kts 105 mph
TAS approx. 131 mph

GPH overall.. .not measured yet.

At 3000 ft I can achieve book value for max speed ( indicated) which in my ship is usually
pretty accurate ( maybe it is the ding in the pitot I refuse to straighten out ! ? ) :mrgreen:

I think I could adjust for a higher static rpm.. but it's pretty close to max.. maybe a little low.

---------------

Question.

Does the rpm and and manifold pressure and ceiling achieved seem "pretty normal"
given a sea level adjustment of the aeromatic ???

One can read various ceilings between 16 and 22 K ft.. depending on where you look.

Could I really get much more out of it, adjusting the prop for higher altitude..
say redline static at 3500 or more feet ?

Kent Tarver talks about much cruising much higher than this with his 0-360
so there you go.

 

[gjordan]

Remember that Kent has a 180 HP engine with a constant speed prop. That is a big difference from a 150HP with an Aeromatic. A Highcruise Aeromatic would probably get you more altitude, but they are rare and Kent says he has trouble getting the engine mounted control valve that the Highcruise uses. Also, I suspect that most of the specs for the Cruisair were written by an ADD MAN rather than a techy guy. In an old club news letter (from the 70s?) there was an article about an altitude test by a 14-19. I think they made 19K before they gave up. I doubt that a Cruisair would make anywhere near what the TC says. ______Grant.

 

[blimpy]

Thanks for the reply Grant.

Well, since I have the 150.. there is no drilling in the front of the case for the control oil nergus.

Back calculating, and using the Aeromatic rpm reduction of 20 RPM per 1000 feet,
and using the Density Altitude of 15,000... I should see an RPM drop of 300.. or 2300 rpm at full throttle
I was seeing 2100... which hints that there could be some adjustment made.

I'd have to sweep the ramp of loose "chips" before I would want to do much extended Full Throttle Run Up
testing at my airport... and I would sure like to have access to a portable digital tach.. before I went too far
down the road of trying to Optimize my Aeromatic to allow Redline operation .

I will now go dig our the power curves for the 150.. and see what 17 inches and 2100 rpm equates to
but it can be very much. 60 hp maybe ?? Sure seems like the airplane ought to true a lot higher than
131 mph at 14,000 feet... since it does so much better at 7500.