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Borer prop benefits pros/cons

J

J3Jim

Registered User
Hey guys,

I need an education on borer props and the benefits on a Pa-18-150. Is there a big ROC increase? What are measurable performance benefits?
I know nothing about them. I’m also curious as to the prop clearance issues as i understand owners will add gear leg extensions or larger tires for prop clearance. And is it all worth it for a grass strip flyer!
Thank you I appreciate it!
 
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What type of plane/engine? Great for trimming brush on new runways, takes a beating and keeps on ticking, Pulls hard off the line. If you are on grass/tar strips and don't plan on a lot of prop abuse the wood props are doing pretty good. Depends on mission. For proper propeller to ground clearance the aircraft must be equipped with an approved combination of wheels and tires that provides a minimum clearancebetween the ground and the center of the axle of 9-3/8 inches, or having extended landing gear per Cub Crafters' STC SA00411SE installed.
DENNY
 
The Borer (lets say 82-42) is going to hurt your cruise speed by probably 8-10 mph for a given RPM versus the Sens (lets say 74-56). With a Borer you'll find most people cruise at least 2400, 2500 is not uncommon. It's also going to reduce your takeoff run by a solid 1/3 and increase your rate of climb accordingly. They also generally run noticeably smoother. The 74" Sensenich series are tuning forks, in my limited experience with them. The Borer also has a lot more air brake effect, when you pull the power back rapidly (not that I advocate it) you'll feel yourself pitch forward. Are they worth it is a matter of your personal goals and budget. I have an 82-42 and I love it. I didn't buy my Cub to go fast, I bought it to get it and out smallish places. Hilltops, river bars etc. The only reason it's not currently installed is I have a Catto 82-39 that I like even more. It produces IDENTICAL performance figures, RPM, ROC, top speed etc. and weighs about 16 lbs less which helps CG and all that which follows. It also runs just a bit smoother. The problem is the Catto isn't certified so it's not actually ''legal". Keep this to yourself though, It's a closely guarded secret and I wouldn't want anybody here to find out. They might turn me in.
 
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DENNY said:
What type of plane/engine? Great for trimming brush on new runways, takes a beating and keeps on ticking, Pulls hard off the line. If you are on grass/tar strips and don't plan on a lot of prop abuse the wood props are doing pretty good. Depends on mission. For proper propeller to ground clearance the aircraft must be equipped with an approved combination of wheels and tires that provides a minimum clearancebetween the ground and the center of the axle of 9-3/8 inches, or having extended landing gear per Cub Crafters' STC SA00411SE installed.
DENNY
Click to expand...
Denny, If i'm reading that right, 8.50's will do the trick, yes?
-- maybe lean on the air pressure a bit to eliminate the squat?
 
I did a ton of mods to my super cub like cuff, extended wing, flaps into the fuse, taller gear, weight out of it and NOTHING came close to the performance difference when I put on that Borer 82/44 ( 160 hp). Nothing. Night and day.
 
PerryB
Yes I believe you are right, had to look at some old posts to double check. Hard to find a cub up here that is not on 31inch bushwheels and extended gear so no one seems to worry about it much. Skis might get a bit low every now and then on stock gear but no one seems to care. A Borer will loose/gain about 2.5 mph for each inch of pitch change. A 82/40 will rip you off the ground but at 2400 will get you about 80 mph with a 160hp. I did fly a Sensenich Airframes had and it came off the ground pretty good and was about 7mph faster than the 82/40. I think the wood/composite props are very nice and great props depending on how rough you are on them. I am sticking with 82/43 Borer for now it is the best "GET YOU BACK HOME PROP MADE".
DENNY
 
DENNY said:
What type of plane/engine? Great for trimming brush on new runways, takes a beating and keeps on ticking, Pulls hard off the line. If you are on grass/tar strips and don't plan on a lot of prop abuse the wood props are doing pretty good. Depends on mission. For proper propeller to ground clearance the aircraft must be equipped with an approved combination of wheels and tires that provides a minimum clearancebetween the ground and the center of the axle of 9-3/8 inches, or having extended landing gear per Cub Crafters' STC SA00411SE installed.
DENNY
Click to expand...
This is the controlling regulation.
CAR Part 3.422
§ 3.422 Propeller clearance. With the
airplane loaded to the maximum weight and most
adverse center of gravity position and the
propeller in the most adverse pitch position,
propeller clearances shall not be less than the
following, unless smaller clearances are properly
substantiated for the particular design involved:


(a) Ground clearance. (1) Seven inches
(for airplanes equipped with nose wheel type
landing gears) or 9 inches (for airplanes equipped
with tail wheel type landing gears) with the
landing gear statically deflected and the airplane
in the level normal take-off, or taxiing attitude,
whichever is most critical.


(2) In addition to subparagraph (1) of this
paragraph, there shall be positive clearance
between the propeller and the ground when, with
the airplane in the level take-off attitude, the
critical tire is completely deflated and the
corresponding landing gear strut is completely
bottomed.


(b) Water clearance. A minimum clearance
of 18 inches shall be provided unless compliance
with § 3.147 can be demonstrated with lesser
clearance.


(c) Structural clearance. (1) One inch
radial clearance between the blade tips and the
airplane structure, or whatever additional radial
clearance is necessary to preclude harmful
vibration of the propeller or airplane.


(2) One-half inch longitudinal clearance
between the propeller blades or cuffs and
stationary portions of the airplane. Adequate
positive clearance shall be provided between
other rotating portions of the propeller or spinner
and stationary portions of the airplane.
 
J3Jim, Is there a measurable ROC increase?
Years ago I did a comparison test between the stock 74-56 and two different "Borer" diameters 80" & 82". There was approximately a 30% improvement in take off time and climb rate. The test also tried different pitch settings.
The 82-42 which Perry mentions is popular. It is useful for those who need maximum take off performance, very shortest take off run. After that it is like driving your car in first gear all of the time.
An 82-44 or an 80-46 will provide nearly as good take off performance and climb as well as much improved cruise speed. I found the 82-44 and the 80-46 to be basically identical in performance.
Both the 80" & 82" are much smoother than the original 74" prop.
 
Buying a Borer or Catto and then attempting to restore original cruise speed with additional pitch has always escaped me, but then again I'm the guy with 4.56 gears in my truck (with 35" tires).
 
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PerryB said:
Buying a Borer or Catto and then attempting to restore original cruise speed with additional pitch has always escaped me. The fatter prop cannot takeoff nearly as well but cruise significantly better.
Click to expand...
What do you mean by "fatter prop"?
A "Borer" prop is a McCauley 1A175GM with a diameter of 82" and a pitch of your choice. Borer is the name of the man who got the STC, Roger Borer.
 
I've edited, but by fatter I meant more pitch. I'm familiar with who Roger Borer is. I said "Borer or Catto" because both props, for a given diameter, have practically identical performance envelope ranges. I've seen several people buy Cattos and go large on the pitch out of concern for cruise speed. I've heard explanations of how well they pull at lower RPM etc, but if you're not making revolutions you're not making power. I didn't put long legs, big tires and VG's on to go fast. Kinda like my truck with the big tires and 4.56's. It's not my freeway cruiser. Yes I'm opinionated, I hope you're not offended.
PS - I have a 1A175GM/42.
 
The 82 inch props on stock length gear don’t comply with clearance requirements on many straight ski installations. I’m not sure many pay much attention to that, but that was part of the motivation to develop and certify extended gear.

Like Pete, I prefer the 82/44 prop for the same reasons he offered: you get 90 % of the takeoff and climb performance, but retain about half the loss of cruise speed. Or so. That’s assuming a healthy engine.

Perry mentioned rpm on takeoff, but don’t forget legal certification limits for static rpm.

MTV
 
I'm not offended. I just like to be certain that everyone has the same understanding of the topic at hand. Some folks are less informed than others and are less prone to understand what is being addressed. Our fellow members here cover the range from a curious enthusiast to many decades highly experienced folks. Sometimes it is difficult to determine which is which when they make no admissions.

When you mentioned fatter, my first thought was a wood prop which is fatter or thicker than a metal one with the same described diameter and pitch measurements.

For what it's worth, my above described tests were done on two different float planes. A land plane will show different results.

The original poster J3Jim indicated that he needed an education, thus a little extra detail has been added.
 
Used to Cubs, an observation: I never expected to see above 100mph in my 0-360 Bushmaster on Peck 2250 floats with experimental McCauley 84/43 P235 prop. At 2400, reading steam and gps, solid 90 knots. Mission: in and out of small lakes where the trout live.
 
J3Jim said:
Hey guys,

I need an education on borer props and the benefits on a Pa-18-150. Is there a big ROC increase? What are measurable performance benefits?
I know nothing about them. I’m also curious as to the prop clearance issues as i understand owners will add gear leg extensions or larger tires for prop clearance. And is it all worth it for a grass strip flyer!
Thank you I appreciate it!
Click to expand...

A bigger thrust disc provides better slow speed thrust. A smaller disc is more efficient for speed. Rate of climb at Cub takeoff speeds will improve a bunch with a Borer. Which pitch you choose should be determined by your target RPM. Most STOL-minded guys I’ve known with 150hp prefer 41 pitch. I liked my pitch to provide 2700 RPM in level full throttle flight. No worry about overspeeding and didn’t give up anything at takeoff that I could notice.

Even with constant speed props the “tractor” class of props, seaplane props, use longer blades for the bigger disc/improved slow speed thrust. Seaplane props are the choice for STOL wheel planes, too, while the go-fast crowd prefers short props.
 
Thanks everyone. So basically an approximate 30% increase in ROC n decrease in TO distance? Cruise reduced.
Once you add the prop and the extended gear to be legal.
How much useful load did you lose?
I’m a fair weather flyer that used to own a J3 so I’m interested in a super cub and simply glad to have the electrical system n starter lol.
So I’m trying to get the basics on a performance increase n expenses to get them and if it’s worth it for someone like me. I will shortly be in the market for a straight SC for local pleasure flying.
I appreciate all your feedback! Thx!


Sent from my iPhone using SuperCub.Org
 
If you run big tires you don't need to extend the gear (unless you go to skis, depending on ski). Once again it is all about the mission. What part of the country are you flying in? Once you clear the ground do you really need a high ROC for pleasure flying? Unless you are going into tight short rough strips a wood/composite prop can give you excellent performance at less weight. No right or wrong just things to look at.
DENNY
 
DENNY said:
If you run big tires you don't need to extend the gear (unless you go to skis, depending on ski). Once again it is all about the mission. What part of the country are you flying in? Once you clear the ground do you really need a high ROC for pleasure flying? Unless you are going into tight short rough strips a wood/composite prop can give you excellent performance at less weight. No right or wrong just things to look at.
DENNY
Click to expand...

Eastern PA. What is typical ROC for a strait SC?
I’m really just trying to learn. I like the greatest ROC as I can reasonably achieve. My J3 C90 did 1000 1200 FPM I lived it n made me feel safer Incase of engine out.

What minimum size tire to achieve clearance?
What is weight increase of Borer prop n weight increase of 3” extended legs?

Thx!!




Sent from my iPhone using SuperCub.Org mobile app
 
J3Jim said:
Eastern PA. What is typical ROC for a strait SC?
I’m really just trying to learn. I like the greatest ROC as I can reasonably achieve. My J3 C90 did 1000 1200 FPM I lived it n made me feel safer Incase of engine out.

What minimum size tire to achieve clearance?
What is weight increase of Borer prop n weight increase of 3” extended legs?

Thx!!




Sent from my iPhone using SuperCub.Org mobile app
Click to expand...

This will give you some information on landing gear: http://www.fadodge.com/?s=extended+landing+gear&submit=

Atlee Dodge is a good source of information. Note that they offer 6 inch extended gear and 3 inch extended gear. With either, you'll also need to replace the cabanes to match.

It's also important to note that these gear legs are a fair bit stouter than stock Super Cub gear legs, as well as longer.

As Denny noted, larger tires may do all you need for clearance.

Borer props are definitely the way to go on a certified Super Cub.

MTV
 
I went back and forth between wood composite and borer. I ended up with the wood composite since I was a little nose heavy and opted for the 18lbs of weight saving off the nose. I had a 76/56 on it and it would cruise at 120mph at 2400 rpm. Which is much faster than others I have talked to with that prop. Not sure why I was faster. Wood composite prop is a 80/42. With the wooden prop I can get off at least 30% faster and probably closer to 40%. Very smooth and lighter on the controls for sure. Went from indicating 115-120mph to 100mph with the 80/42. This is with a super cub 150. Which I believe it is a little over propped with the 80/42. But going to turn the 150 into a 160 soon as I can stop flying it long enough to send the jugs off. Hope this helps you!
 
Thanks for that data I appreciate it! Who makes the composite wood? I don’t know anything about that combination?
I was reading good things with a wood prop too from Denny’s link above.


Sent from my iPhone using SuperCub.Org
 
J3Jim said:
Thanks for that data I appreciate it! Who makes the composite wood? I don’t know anything about that combination?
I was reading good things with a wood prop too from Denny’s link above.


Sent from my iPhone using SuperCub.Org
Click to expand...



Sensenich makes its. They make them in special batches. Took about 6 weeks to get mine. They are about 3-400 cheaper than the borer. They make a 80-38, 80-40, 80-42. Don at Sensenich said the 80-40 was optimal for the 150 and the 80-42 was best on the 160hp for climb performance. I talked with a few guys that were running them and said the pulled about has hard as the borer but when you are really heavy the borer would pull a bit harder. The wooden composite is a lot thicker than the aluminum props. It was amazing how much light the wooden composite was compared to the 76-56 I took off. Night and day difference. About half the weight. I have not flown a cub with a borer so can't help you there. I am happy with mine so far.
 
When you say wood “composite” is that different than a standard Sensenich wood propeller? What is composite?


Sent from my iPhone using SuperCub.Org
 
8.50 tires or 3" extended gear will give you the proper prop clearance with the 82" McCauley 1A175 "Borer" prop. Hurts the cruise but the take off performance is worth it to me. Depends on your mission I guess. My 150 hp Super Cub on 700x6 tires, covered stock gear and Sensenich cruise prop would go 100 plus mph. With an 1A175-8241, 31" Bushwheels, 3" uncovered gear I cruise about 90 mph. Cruise speed is not my goal, I like to land on short spots. If I want to go faster I take my brother's PA16.
 
J3Jim said:
When you say wood “composite” is that different than a standard Sensenich wood propeller? What is composite?


Sent from my iPhone using SuperCub.Org[/QUOTE


https://www.airframesalaska.com/category-s/1979.htm

I tried to add the link. If it does not work. Go to airframes Alaska. Click on Reeve air motive. Sensenich propellers. You will see it. It is also on the white super cub on the airframes Alaska cover page. If you are interested call Gabe at airframes Alaska. He can tell you more about them. Thats who I delt with. Great guy! Its a birch wood propeller I think with a composite material over it with either stainless or nickel leading edge.
Click to expand...
 
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