Performance Difference
- Thread starter dtreid
- Start date
Dan Cullman
New member
The biggest difference will be determined by the aerodynamic cleanliness
and "trueness" of the airframe. There can be big differences with the same model airframe and engine.
Dan
and "trueness" of the airframe. There can be big differences with the same model airframe and engine.
Dan
Dan Cullman
New member
Weight is the important factor here..with the same airframe involved.
Engine and propeller variables are just that...variables. We are not talking about a lot of horsepower difference here. In general, the Aeromatic should deliver better takeoff performance. However, you can always find a fixed pitch metal prop that will beat the Aeromatic in the takeoff performance realm...on that same airframe/engine combination.
You will note that all the Supercub guys that want the best short field/climbout performance go for the large diameter, fine pitch metal props. They are not interested in cruise performance.
In short, the Cruisair is not and never will be an STOL airplane. A good all around airplane...but a Storch, it is not.
Dan
BTW, what is the empty weight of your airplane?
Most of the 14-13 series airplanes left the factory weighing 1250-1300 lbs.
The pilots weighed 150 lbs.
Unfortunately, everything has been supersized, except the published gross weight for this airplane.
Engine and propeller variables are just that...variables. We are not talking about a lot of horsepower difference here. In general, the Aeromatic should deliver better takeoff performance. However, you can always find a fixed pitch metal prop that will beat the Aeromatic in the takeoff performance realm...on that same airframe/engine combination.
You will note that all the Supercub guys that want the best short field/climbout performance go for the large diameter, fine pitch metal props. They are not interested in cruise performance.
In short, the Cruisair is not and never will be an STOL airplane. A good all around airplane...but a Storch, it is not.
Dan
BTW, what is the empty weight of your airplane?
Most of the 14-13 series airplanes left the factory weighing 1250-1300 lbs.
The pilots weighed 150 lbs.
Unfortunately, everything has been supersized, except the published gross weight for this airplane.
blimpy
New member
this could devolve into the argument I heard once... about whether "a tai chi" could beat a "kung fu".
Too many variable to be an answerable question.
You realize you have a zillion variables.. right ?... two engines, and How many Props ???
A "fixed" pitch can be almost anything... but are generally either: Climb, Compromise, or Cruise.
Most props out there are compromise props.
So comparison to a "fixed" is just so much jello on a wall.
The aeromatic is ground adjustable. You can make it do almost anything you want it to do... with-in limits.
It does have a specific set of blade dimensions and angles - specific to the bellanca.
So there is a limit of sorts there, redline rpm being the other.
There are also similar limits to what could be specified in any legal fixed pitch prop.
---
Assuming the Aeromatic is set up Correctly I will say this about it:
The Aeromatic is what allows the relatively low powered 150 hp cruisair perform so well.
Most 150's with fixed pitch report about 5mph slower cruise, and most folks see them climbing out slower
with compromise props. As expected. Dan's comments about bush planes is spot on.
In general, that airplane will take off shorter, climb out faster, and cruise faster than a normal compromise
fixed pitch prop ON THE SAME AIRPLANE.
MORE power will boost the take off performance, with either prop.
Many guys have switched from 150 to 165 ( parts availability).. and they can tell you how much difference
it made... if they kept an aeromatic when they did it.
It takes a HUGE increase in power to make an airplane cruise even a few mph faster.
But even modest increases in power can make substantial improvement in climb and take off.
Some form of "constant speed" prop has always been the patch to higher performance across the board.
If you want immediate take off, and 450 hp.. get a stearman. It wont go fast enough for you to get lost.
Currently, the type holder of the Aeromatic Prop, is in a protracted pissing contest with the FAA,
and is temporarily without a repair station license. This could be a problem, if your aeromatic needs
major repair soon.
However, the props are dirt simple, and very durable. If yours is good, it will stay that way a very long time.
Kent's son is a great craftsman, and knows the props well... so in the long run I wouldn't worry about buying an aeromatic.
I would not have bought my airplane without it !
Too many variable to be an answerable question.
You realize you have a zillion variables.. right ?... two engines, and How many Props ???
A "fixed" pitch can be almost anything... but are generally either: Climb, Compromise, or Cruise.
Most props out there are compromise props.
So comparison to a "fixed" is just so much jello on a wall.
The aeromatic is ground adjustable. You can make it do almost anything you want it to do... with-in limits.
It does have a specific set of blade dimensions and angles - specific to the bellanca.
So there is a limit of sorts there, redline rpm being the other.
There are also similar limits to what could be specified in any legal fixed pitch prop.
---
Assuming the Aeromatic is set up Correctly I will say this about it:
The Aeromatic is what allows the relatively low powered 150 hp cruisair perform so well.
Most 150's with fixed pitch report about 5mph slower cruise, and most folks see them climbing out slower
with compromise props. As expected. Dan's comments about bush planes is spot on.
In general, that airplane will take off shorter, climb out faster, and cruise faster than a normal compromise
fixed pitch prop ON THE SAME AIRPLANE.
MORE power will boost the take off performance, with either prop.
Many guys have switched from 150 to 165 ( parts availability).. and they can tell you how much difference
it made... if they kept an aeromatic when they did it.
It takes a HUGE increase in power to make an airplane cruise even a few mph faster.
But even modest increases in power can make substantial improvement in climb and take off.
Some form of "constant speed" prop has always been the patch to higher performance across the board.
If you want immediate take off, and 450 hp.. get a stearman. It wont go fast enough for you to get lost.
Currently, the type holder of the Aeromatic Prop, is in a protracted pissing contest with the FAA,
and is temporarily without a repair station license. This could be a problem, if your aeromatic needs
major repair soon.
However, the props are dirt simple, and very durable. If yours is good, it will stay that way a very long time.
Kent's son is a great craftsman, and knows the props well... so in the long run I wouldn't worry about buying an aeromatic.
I would not have bought my airplane without it !
Larry Lowenkron
New member
Actually, as I have previously posted...I found very little difference between my fixed pitch McC and my Aeromatic with my 150hp. I switched years ago, before Kent had the TC, because it looked like there was going to be an AD, and the only prop shop that I knew that worked on Aeromatics was not the most "upstanding" in my opinion. The diff in ROC and TAS was a 50 fpm decrease to 9500 ft and an increase in TAS by 3 kts. I had my Aeromatic set so that I could get 2650 rpm on TO if I needed it. I would run it to 2600 in climb. I have also noticed that when I briefly run at 2600 RPM, my TAS increases more than it should by Sac Sky Ranch figures. At that time, I had a mechanical tach, and do not really know how accurate it was. I switched to a digital tach after I had my little incident in Pierre, SD and other than a little straightening of the prop, there was no other change.
I talked with Scott Thomas who made the "switch" and he said it was well worth the change. I'll report on what I find after I get my changed (hopefully later this year). I have parts out on the 165 being NDT'd now. Hope, hope, hope...!!!
I talked with Scott Thomas who made the "switch" and he said it was well worth the change. I'll report on what I find after I get my changed (hopefully later this year). I have parts out on the 165 being NDT'd now. Hope, hope, hope...!!!
Dan Cullman
New member
LL,
You have all the stuff to build a 165?
Dan
You have all the stuff to build a 165?
Dan
Larry Lowenkron
New member
Hi Dan,
I am working with Terry Hellickson who bought Gene Hamilton's business. I think I have all of the parts. Problem is going to be to get it to fit. I can already see some interference with my intake tubes and motor mount, am also wondering about the possible interference between my cowl flap and the bigger MA-4.5 carb. I know it can be done because there are so many out there, just have to see how it's done.
LL
I am working with Terry Hellickson who bought Gene Hamilton's business. I think I have all of the parts. Problem is going to be to get it to fit. I can already see some interference with my intake tubes and motor mount, am also wondering about the possible interference between my cowl flap and the bigger MA-4.5 carb. I know it can be done because there are so many out there, just have to see how it's done.
LL
blimpy
New member
interesting comments Larry.
the aeromatic does lose 20 rpm per 1000 feet... so at some point perhaps the fixed pitch cruise has an advantage at
high altitudes ... but I don't know in practice.
again depends on what the aeromatic was set up to do
and what the dia and pitch of the fixed prop is.
I was wondering today how accurate a good mechanical prop is.
I don't run my engine above 2500 in cruise or descent, generally closer to 2400 or 2450.
2500 is only 100 rpm shy of the 2600 rpm redline ( 150 hp).. and that is only 4%.
That's pretty close tolerance for a mechanical device.
I'd love to compare mine to a known good electronic tach, to make a calibration chart.
Q. if your prop allowed your engine to overspeed in cruise, weren't you losing the advantage of
best pitch.. and losing a little speed that way ?
the aeromatic does lose 20 rpm per 1000 feet... so at some point perhaps the fixed pitch cruise has an advantage at
high altitudes ... but I don't know in practice.
again depends on what the aeromatic was set up to do
and what the dia and pitch of the fixed prop is.
I was wondering today how accurate a good mechanical prop is.
I don't run my engine above 2500 in cruise or descent, generally closer to 2400 or 2450.
2500 is only 100 rpm shy of the 2600 rpm redline ( 150 hp).. and that is only 4%.
That's pretty close tolerance for a mechanical device.
I'd love to compare mine to a known good electronic tach, to make a calibration chart.
Q. if your prop allowed your engine to overspeed in cruise, weren't you losing the advantage of
best pitch.. and losing a little speed that way ?