Major update
coming…please stand by.
Ok, so as I think I have
mentioned in the past I love my Catto 3 bladed prop. That is to say I
love it at cruise, but not so much on takeoff. Well I decided that I
would switch to a Whirlwind constant speed prop and that is the topic of this
post. I will start out with some pro’s and con’s as well as a few notable
comments about the process. This is coming from somebody who has never
flown constant speed and the experience of flying both is fresh in my mind.
- Pro’s
- Takeoff—holy cow the
takeoff! I did several touch and go’s as part of my testing process
and I can’t tell you how amazing the pull on this prop is at full
RPM. I was climbing out at Vy for these touch and goes and I was at
pattern altitude before I was turning crosswind! If I tried to
climb at Vx I felt like I was going straight up!
- Taxi slower. At idle the
prop does not pull as hard as my fixed pitch prop did so I can now taxi
slowly without using so much braking or running the engine at a very low
RPM where it shakes like a wet dog. Very nice.
- Slowing down. Pull the
throttle in the air on this prop and it feels like somebody literally hit
the brakes!
- Landings are VERY short.
- Con’s
- Price
- I can no longer use engine
sound as a primary indicator of many aspects of flight. This may be
something I learn to adapt to but I like to use the sound of the engine
as an indicator of speed for many phases of flight
- Complexity
- Flight management is more
complex because now I have to think about a prop setting in addition to
the rest of the flight. However, this will become “muscle memory”
soon I’m sure.
- Engine. Prop governor,
oil hoses, another cable run with associated firewall penetration and
attach bracket all on the very tight back side (firewall side) of the
engine.
- Adjusting of the high speed
stop is a bugger due to location and limited access… and it has to be
safety wired…hell I can’t hardly get one hand back there let alone 2 and
some lock wire tools. Fortunately I have a great friend Harry who
has a nice lock wire tool that is a single piece of wire with crimp on ends.
I was able to get that in there…barely.
- Air brakes. Yes I know I
listed this in the Pro’s section but there is a negative side to this
too. I say this with a caveat that I might be doing something wrong
but when I pull the power as I think would happen in an engine out
situation my glide ratio tanks….big time. With my fixed pitch prop
if I pulled the power my glide ratio was about 12:1. With this prop
I don’t know if its even 6:1. I have to be missing something here
but I believe the prop is designed to go to the high speed top (at least
that’s what the spring does) on a loss of engine oil pressure.
- Slightly less smooth.
Going from a 3 blade prop to a 2 blade prop I noticed a slight increase
in vibration. Not much but noticeable. I still haven’t done the
dynamic balancing yet so that will likely help.
- Notable – this is a section for
things I noticed that are noteworthy but may change
- Landings are way
different. I got used to the size of the pattern I needed to land
my Catto prop. I had it down pretty good to where I could pull
power at the threshold on downwind and fly the rest of the pattern to
landing without adding power. That is no longer true…I’ve yet to
land without having to add power to get to the runway and that’s after
cutting my downwind leg past the threshold in half! Not only that
but I feel like I’m coming in hot because the engine is running at a
higher RPM than I am used to so I come in slower than normal. This
will all go away when I get used to the new prop but its an eye opener for
now.
- LOP operations are a bit
challenging right now. As I mentioned I use engine noise to help me
in many phases of flight. LOP is one of those areas. I
usually lean until I hear the engine start to slow (lower RPM) but now
the RPM remains constant and the power drops off. I have to pay
close attention to EGT’s now while leaning. Along those lines I
still need to figure out where best economy is as well as best
power. That will take some time.
- Nose is slightly heavier now
so I can’t keep the nose wheel off the runway as long on my landing roll-out. This could be partly due to the fact that this prop slows
down so quickly.
- The recommended 2 ¼” prop
extension that allows this prop to be attached to my engine with a James
cowl is too long. With my previous extension I had about ¼” of
space between the spinner and the fwd edge of the cowling. Now that
gap is ¾” or slightly more. I emailed Sam Tillman at SaberMFG to
see if he has a shorter extension.
- My prop is the wrong
color. ☹ I ordered a white prop with blue crescent
stripes to match my color scheme. The prop I got is black with
white stripes. Its beautiful but doesn’t quite match. Black
and white go with everything so worst case scenario its not a big deal
but its not what I ordered.
- Torquing the prop on was a
bugger. I don’t have the “special” tool needed so I had to put
together a combination of tools to get the job done. I also needed
another set of hands to hold the prop while I was torquing. I’m
going to break out the welder and make a tool to do the torquing since
I’m sure I will have to remove the prop sooner or later…even if its only
to replace the alternator belt.
- Speaking of alternator belts,
since the prop was off I went ahead and replaced the belt. I also
took the time to do a few other housekeeping tasks such as riveting the nut-plates on my battery box.
And now some
pictures....
