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Cox Engine of The Month
Propeller question
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Propeller question
For buyers looking for a "pusher" prop, we offer this one, together with instructions on how to mount / run, so that leading and trailing edges perform in the proper direction:
https://coxengines.ca/propellers/cox--049-propeller-left-hand-pusher-5-x-3-5.html
Conversely, can any right-hand prop be mounted "hub-reversed" and run left-hand (pusher mode) without degrading performance?
https://coxengines.ca/propellers/cox--049-propeller-left-hand-pusher-5-x-3-5.html
Conversely, can any right-hand prop be mounted "hub-reversed" and run left-hand (pusher mode) without degrading performance?
Re: Propeller question
I don't know about the different type of propeller that could offer better performance but I can give you something with the motors to use is the small modification I made to improve the performance with two trust washers the friction is greatly reduced resulting in less wear less friction possible to mix two types differing from one metal to one fenolic wit the tee dee engine two washer wil Not fit direct modification To crankcase and prop drive plate one washer One with a larger inside diameter to fit over the larger portion of the crankshaft
davidll1984- Diamond Member
- Posts : 2327
Join date : 2020-02-12
Age : 39
Location : shawinigan
Re: Propeller question
Do ya like to read? If not, here’s some homework for ya!
https://journals.sagepub.com/doi/full/10.1177/1756829316638206
There are a couple of pictures just to keep you interested!!
https://journals.sagepub.com/doi/full/10.1177/1756829316638206
There are a couple of pictures just to keep you interested!!
Marleysky- Top Poster
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Posts : 3618
Join date : 2014-09-28
Age : 72
Location : Grand Rapids, MI
Re: Propeller question
It works.
Last edited by Levent Suberk on Wed May 12, 2021 12:45 am; edited 1 time in total
Levent Suberk- Diamond Member
- Posts : 2258
Join date : 2017-12-24
Location : Türkiye
Re: Propeller question
You can fly the prop as a puller with a reed engine.
The TD is limited to pusher only unless you have a left hand crank.
The TD is limited to pusher only unless you have a left hand crank.
1/2A Nut- Top Poster
- Posts : 3531
Join date : 2013-10-19
Age : 61
Location : Brad in Texas
Re: Propeller question
Cox International wrote:can any right-hand prop be mounted "hub-reversed" and run left-hand (pusher mode) without degrading performance?
I see no performance-related reason why it wouldn't work.
However, I don't like the idea of running the engine in the "wrong" direction, because that will have a tendency to loosen the prop screw while running, rather than tightening it when running in the "normal" direction. Not sure how much of a problem that would be in practice.
Obviously, running the engine "backwards" is only an option for reedies.
dirk gently- Gold Member
- Posts : 430
Join date : 2012-02-03
Age : 42
Location : Poznań
Re: Propeller question
Not sure if the question has actually been answered to a degree of certainty.
The way we see it is that every propeller has a leading as well as a trailing edge. If the prop is mounted "hub-reversed" and run in the opposite direction, then the aerodynamics remain the same but one ends up with a "pusher" prop.
Of course TD engines would need a LH crank and there will be the "screw-coming-loose" issue.
Was just looking for a confirmation because we constantly get requests for pusher props.
The way we see it is that every propeller has a leading as well as a trailing edge. If the prop is mounted "hub-reversed" and run in the opposite direction, then the aerodynamics remain the same but one ends up with a "pusher" prop.
Of course TD engines would need a LH crank and there will be the "screw-coming-loose" issue.
Was just looking for a confirmation because we constantly get requests for pusher props.
Re: Propeller question
Most people may well prefer pusher props, as the running direction of the engine then stays the same.
Appart from the prop screw issue, there is also the need for a reverse spring starter and relearning how to flip the prop etc.
Appart from the prop screw issue, there is also the need for a reverse spring starter and relearning how to flip the prop etc.
Surfer_kris- Diamond Member
- Posts : 1912
Join date : 2010-11-20
Location : Sweden
Re: Propeller question
Surfer_kris wrote:Most people may well prefer pusher props, as the running direction of the engine then stays the same.
Appart from the prop screw issue, there is also the need for a reverse spring starter and relearning how to flip the prop etc.
Yes, except that pusher props are almost non existing.
Also, we do sell the LH starter springs.
Re: Propeller question
Cox International wrote:Not sure if the question has actually been answered to a degree of certainty.
The way we see it is that every propeller has a leading as well as a trailing edge. If the prop is mounted "hub-reversed" and run in the opposite direction, then the aerodynamics remain the same but one ends up with a "pusher" prop.
Of course TD engines would need a LH crank and there will be the "screw-coming-loose" issue.
Was just looking for a confirmation because we constantly get requests for pusher props.
Yes, 100% if you mount a tractor prop backwards, and run the engine in the opposite direction, you have a pusher configuration. Also, I have run many reedies as pushers, and have never had the prop screw loosen. Ever.
ajcoholic- Beginner Poster
- Posts : 5
Join date : 2017-12-23
Re: Propeller question
ajcoholic wrote:Yes, 100% if you mount a tractor prop backwards, and run the engine in the opposite direction, you have a pusher configuration. Also, I have run many reedies as pushers, and have never had the prop screw loosen. Ever.
Andrew --
Nice to see a name from the old RCU group showing up here. Don't be a stranger.
The "other" Andrew
Marleysky- Top Poster
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Posts : 3618
Join date : 2014-09-28
Age : 72
Location : Grand Rapids, MI
Re: Propeller question
Cox International wrote:Conversely, can any right-hand prop be mounted "hub-reversed" and run left-hand (pusher mode) without degrading performance?
For all practical purposes, a prop doesn't care whether it's pushing or pulling. The only real considerations of using a tractor prop in a reed engine as a pusher are 1) the air flow around the fuselage before getting to the prop, and 2) the drag on the drive plate against the crankcase. As a tractor, it's in clean air and is most efficient. As a pusher, it's in dirty air and not as efficient. As for the case drag, I don't know if the drag of the back of the prop hub in a pusher configuration is more or less than the drag of the crank hub against the face of the thrust bearing in the case. But as for the prop itself, as long as the curve is forward, it's good to go.
The Dr. Doolittle Mark
batjac- Diamond Member
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Posts : 2371
Join date : 2013-05-22
Age : 61
Location : Broken Arrow, OK, USA
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