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Constant Speed... Why Not?...

FlipFlop

FlipFlop

Registered User
Maintaining at Flight Level Zero, requesting lower
They're heavy, expensive, and add complexity...

But...

If I had a CS prop and flew from here to Big Creek, ID (my favorite), I'd probably knock off a couple of hours of flight time and still have a climb prop went I got there...

In my younger days, I knew a guy with a Tripacer who installed an O-320 and CS off an Apache, like a whole new airplane...

I see Atlee has an STC to install a CS on a Super Cub, but I don't think I've seen one installed and I know I haven't seen you guys write about it...

There'sgotstobeareason! or Therestofthestory!...
 
I have a 76" constant speed on my bushmaster. With 26" tires, I get 120mph at 65% (81/2gph) and 130mph at 75%(10 1/2gph). My plane is a little bigger than a cub (37.5' wingspan) but fairly light 1194lb. empty. I think a long "Borer" at 2700rpm will produce alittle more thrust.

Don
 
CS Prop.

Jim Richmond at Cub Crafters has done some testing with the constent speed prop and said it just didn't have the thrust coming out of the hole like a Borer prop. My neighbor had a PA-18 160 with a CS prop and has now converted over to a 180 hp with the 84" thin blade (like a Borer only 2" longer) Pawnee prop. This setup really works well on the PA-18 and most guys are seeing 105 mph at 2400 with it. He said the same thing about the CS prop, it was a dog on take off. Crash
 
I have a MT 80" CS electric controlled/operated prop on my 160hp Wag Aero Super Cuby. I was told by the builder that is was about the same weight as the borer prop he took off. Cheers!
 
I flew a Cub with the borer for one company and an other with constant speed for the other.

I believe it was a 80 inch Hartzell -- Hands down the better plane to haul a load Cruise at close to 120Mph cruise

(26 inch tires back than were big) and much improved climb.

That thing would climb 500 feet per minute at 100MPH indicated and max weight (150 HP engine).

The one with the borer was a dog in comparison good for a few seconds on take of and just sad after that.

The guys complaining about the constant speed are the ones that never did fly one.
 
There is absolutely no better performance enhancement for the weight and money than a constant speed prop. Anyone who tells you otherwise should take a ride and convince themselves. The money spent on a light MT prop or Whirlwind...even more so.

I had an 83" MT on my Husky and it flat out honked in comparison to the Hartzell.

My big fat cub thing swings an 88" MacCaulley and is impressive from climb, to cruise to massive aerodynamic braking when you want it. Nothing shy of impressive. It gives you a whole different realm of performance than what you contemplate without...

Steve.
 
I Had a carbed 520 on a 180 for several years, never had much of a issue with carb ice.

They however need the restrictor on the Air filter for cold weather ops.
 
If my cub project ever gets done it I am going with a trailblazer prop. Not really worried about it being nose heavy I always carry 45 lbs of tools, tie down gear, survival gear. I can stick a lot of weight in the extended upper baggage if the stabilizer does not fix any problem first. I don't remember if I mentioned this before but if you adjust your trim when you are flying the nose won't feel heavy. ;) My main worry is it won't hold up to hard bush use like a Borer will I can always go back to a fixed pitch if needed.
DENNY
 
Our PA-18 (160hp) we acquired had a MT 2 blade reversible pitch prop. Had a placard to have 150# in baggage if flown solo. Nice, flew fast and smooth. Removed it due to it being VERY nose heavy and with hydraulic skis it was so heavy approach speed was close to 50 unless you came in behind the power curve then touchdown was tail first. Plus side was you could load the hell outta the back and the heavy nose balanced it out. We were going to add ballast but why make a 1260# cub even more heavy. The prop sat a couple inches further forward as well which did not help. After needing a prop blade leading edge repaired and seeing the cost and downtime we decided to convert it back to a fixed pitch borer and never looked back. No more high speed cruise but not nose heavy anymore and lands much slower at a better deck angle. The prop just didn’t fit our mission. And yes I did fly it quite a bit before I decided to remove it. I’m not in a rush and hands down like the Borer better maybe even try the new ground adjustable prop everyone is raving about.

Sold it to a member who would get better use outta it. FWIW here were the weights I posted years ago after removal.

MT PROP MTV-15-C-C-R(M)
Spinner/hardware/flange bushings. 55.3lbs (no oil in hub)

Oil hose/governor/governor pad and drive gear
Firewall extension box/control cable/annunciator/
Switch/breaker and air/speed switch. 9.9lbs

Total 65.2lbs

The weight of the Borer 8243 all hardware and components to convert to fixed pitch added up to 36.7lbs.
 
I’m collecting parts for a new 4-place build. Still waiting for the fuselage but have the engine and prop. I went with a Titan IO-370 and have a Hartzell 83” Trailblazer. My mission is good performance on both ends and don’t mind a little compromise on weight. I also like to run full manifold pressure and set the rpm where I want it. When I go somewhere it is often necessary to climb fairly high, 7500’ to 9500’ is common, full MP is nice without redlining the rpm. So good cruise potential and the guys I’ve talked to say the Trailblazer really pulls on the low end. FWIW
 
spinner2 said:
I’m collecting parts for a new 4-place build. Still waiting for the fuselage but have the engine and prop. I went with a Titan IO-370 and have a Hartzell 83” Trailblazer. My mission is good performance on both ends and don’t mind a little compromise on weight. I also like to run full manifold pressure and set the rpm where I want it. When I go somewhere it is often necessary to climb fairly high, 7500’ to 9500’ is common, full MP is nice without redlining the rpm. So good cruise potential and the guys I’ve talked to say the Trailblazer really pulls on the low end. FWIW
Click to expand...
Paul Claus had a trailblazer on his four place when I rode with him. He really liked the way it pulled. It was a little nose heavy with two up front and only day gear in the back. Tightening the helper spring might have fixed that as it was rigged very slack
 
The old rule of thumb I heard was up to 180 hp, fixed pitch is the way to go. Above 200 hp, constant speed is the way to go. Between 180 and 200, dealers choice. Constant speed props were revolutionary giving you a cruise prop when you needed and a climb prop when you need with little pilot supervision. However, the are significantly heavier than a fixed pitch, more complicated, and more expensive. Being more complicated, they also need more maintenance and that maintenance is also more expensive. Prop ADs are almost exclusively on constant speed props. On my 230 hp 180, I have a constant speed. Love it, glad I have it. On my 187 hp super cub, I'm going with a ground adjustable Catto. When i want to go somewhere I'll make it into a cruise prop and change it to a climb prop when iget there.
Wayne
 
There are a couple things I think are not very much talked about in the equation. The first is
The fact that the constant speed propellor delivers far more thrust at both initial acceleration and continues throughout the takeoff run, shortening the takeoff roll considerably, when corrected to the same weight.

Not to say that a light Supercub might not beat a heavier machine off the ground, cuz I know they can.

But heavy…. No comparison. Constant speed wins.

The most functionally beneficial advantage however, isn’t shortening takeoff runs.

Aerodynamic braking is. The ability to come in over obstacles and use the prop to drop in and over without picking up a bunch of speed is a real benefit.

I also love the ability to configure to lots of real world scenarios. I can configure my power output at various speeds far more than with a fixed prop. From high altitude cruise to low and slow and anything in between.

If I want to loiter and lump along at 1750rpm and 19 or 20 inches MP…I can run my 520 under 9.5gph loafing along at 85ias

If I want to run 24/24 and 15 gph at 130 ias… no sweat.

Climb 2000 a minute? No sweat.

Get into 700foot strip over 60 foot wires? You bet.

I appreciate that different people have differing missions for different configurations of planes. But for all around performance, I will maintain that a constant speed propellor is the best performance increase for the money.

One thing I notice is that upon breaking ground, I accelerate WAY differently than fixed pitch airplanes. Once through 50feet, I’m heading for 90mph in climb going up over a thousand fpm…which means I spend far less time going slow, nearest the ground. I’m up and out of the height/ velocity curve real quick. And I like that. Options are good.

Now if that engine ever quit with that big flat prop…I’d probably have my hands full… which brings me to 35” Alaska bush wheels.
Safety gear, for sure on the worst day.

Steve
 
There is something magical when flying a light Cub, especially when the nose is kept light. It feels like you wear the airplane and it’s an extension of oneself. In the flare, there always seems to be that extra couple of inches of stick travel to keep the nose up. The elevator doesn’t run out of authority like an airplane with a lot of weight up front.
 
FatCub300 said:
Now if that engine ever quit with that big flat prop…I’d probably have my hands full… which brings me to 35” Alaska bush wheels.
Safety gear, for sure on the worst day.

Steve
Click to expand...
In that case, just pull the prop control all the way back to full high pitch. The drag will disappear, actually having less drag than any fixed pitch prop. Try it without shutting down the engine, your eyes will be opened.
 
sea2jet said:
There is something magical when flying a light Cub, especially when the nose is kept light. It feels like you wear the airplane and it’s an extension of oneself. In the flare, there always seems to be that extra couple of inches of stick travel to keep the nose up. The elevator doesn’t run out of authority like an airplane with a lot of weight up front.
Click to expand...
If you need/want more elevator authority in the flair use that trim handle on the left side of the seat and adjust the stabilizer properly. That is the cheapest fix around.
DENNY
 
I am 68 years old and had seven bypasses. I have no problem with stick pressure on a full power, full flap, full nose up trim go around. You need to do a few push ups if you do. Once you shove the black knob forward just dial the trim back, what does that take 2 seconds? The reality is a cub will stop descending and start slow climb at 1800-1900 RPM in that configuration. Do you really need to go full power??? Use the power needed to to clear what is in front of you. Remember go arounds are not always free. Sometimes it is just better to land and take what you get.
DENNY
 
DENNY said:
I am 68 years old and had seven bypasses. I have no problem with stick pressure on a full power, full flap, full nose up trim go around. You need to do a few push ups if you do. Once you shove the black knob forward just dial the trim back, what does that take 2 seconds? The reality is a cub will stop descending and start slow climb at 1800-1900 RPM in that configuration. Do you really need to go full power??? Use the power needed to to clear what is in front of you. Remember go arounds are not always free. Sometimes it is just better to land and take what you get.
DENNY
Click to expand...
I want full power on any go-around
 
sixmile said:
I want full power on any go-around
Click to expand...
The point is, getting to full power can take a few seconds. It’s really not a big deal.
My fat beast has electric flaps and I hit the up button and feed in power they are coming up, re trimming as I go.

It’s doesn’t have to be this great big massive emergency full power, pitch, thing.

In fact, I do this a lot, when making evaluation passes on off airport LZ’s pretty routinely.

Totally agree with Denny.
 
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