Dumb question

The engine instructions seem to be determined being in Front.

jbanes1961 wrote:Does a cox engine run clockwise or counterclockwise  (looking at front of engine). Just trying to make sure I have this starting spring installed correctly.

I don't think it's possible to install the spring the wrong way- It just won't fit. The spring you have will determine the direction of rotation.

Rotation is measured from the pilot's seat

Cox International wrote:Rotation is measured from the pilot's seat

On real airplanes and our RC planes yes, that would seem the best way to define it. But with the advent of Quad copters they now seem to look at it from the front instead....  

So LH (left-handed) and RH (right-handed) are a much better designations, as it doesn't matter where you stand or sit, a right-handed thread is always a right-handed thread.

Master Airscrew is adding yet another term N (normal) for when the prop should rotate CCW when seen from the front:
https://www.masterairscrew.com/pages/pusher-vs-tractor-propellers

(So LH (left-handed) and RH (right-handed) are a much better designations)

But, depending on where one stands, LH becomes RH and RH becomes LH. Behind a RH prop, it turn CW, relative to sight. In front of the same prop it turns CCW, relative to sight.

We ran into confused customers all the time with our props and springs, until we specified the position relative to the prop on our listings, because customers sometimes (often) viewed rotation when in front of the airplane and ended up buying the wrong prop or spring. We rarely run into this issue now

Thanks again for the great responses. Armed with a little more knowledge, I dont believe that the spring can be installed wrong. It seems to be idiot proof for the most part. And it winds and releases in the same directions as the instructions that were posted suggests. So I think I'm in good shape. So this particular engine and spring set up runs the engine in a right hand direction as seen from the pilots seat. Thank you all so much.

It is virtually impossible to install the spring wrong.

The issue that can arise is a mis-match between spring and prop

One other issue to consider is whether the engines have round or hex-shaped drive-plates, as the springs are different for each version and are not interchangeable unless one also changes the drive-plate.

Cox International wrote:
But, depending on where one stands, LH becomes RH and RH becomes LH.

No, that is not correct. A righthanded (RH) screw is always a righthand threaded screw, no matter where you stand or view it from. You will always tighten a RH threaded bolt in same direction, there is never any question about how it works.

A righthanded airscrew works the same way. There is no question in what way it should be rotate in order to move forward. It is only when one starts to talk about CW and CCW that things become "complicated" as now it is dependent on where you stand or watch the airscrew from.

Cox International wrote:
We ran into confused customers all the time with our props and springs, until we specified the position relative to the prop on our listings, because customers sometimes (often) viewed rotation when in front of the airplane and ended up buying the wrong prop or spring. We rarely run into this issue now

If you are defining it by looking from the cockpit, you will be doing the opposite way to the quad market and master airscrew (as I linked to above), so yes this is surely an issue.

If I'm looking at prop from front, it is rotating to the left, if I'm looking at prop from cockpit it is rotating to the right. Even tho a screw is tightened to the right if I'm looking at it and it will always tighten to the right, if I'm standing behind the screw, I will be turning it toward my left hand to tighten it. That seems more confusing than having a definite orientation that is always used. If it had a standard orientation, then cw and ccw would work fine. The only confusion seems to be which way to view the engine. Is that clear as mud?

Well, do you ever have to think about which direction to tighten the prop nut?
That is usually very clear to most people and that is a RH thread. Then depending on where you stand one can easily work out which way it should be turned. Would you really prefer to call screw threads by CW and CCW instead?

A RH prop work exactly the same as a RH screw, and it is easy enough to understand, isn't it...?

Surfer_kris wrote:

Cox International wrote:
We ran into confused customers all the time with our props and springs, until we specified the position relative to the prop on our listings, because customers sometimes (often) viewed rotation when in front of the airplane and ended up buying the wrong prop or spring. We rarely run into this issue now

If you are defining it by looking from the cockpit, you will be doing the opposite way to the quad market and master airscrew (as I linked to above), so yes this is surely an issue.

Yes, with quads it seems to be different because one is looking onto the rotors (or whatever those four whirlygigs are called). However, as we cater to the Cox community, we adapted the Cox formula for rotation; whereas their starter cams are stamped "L" and "R" and some of their LH props are stamped "L.H."; basically as viewed from the cockpit.

It gets really interesting when someone inquires about a pusher-prop and we recommend a LH prop, mounted "hub-reversed" and run RH (to maintain leading / trailing edges). That's enough to even confuse us here.

Surfer_kris wrote:Well, do you ever have to think about which direction to tighten the prop nut?
That is usually clear to most people and that is a RH thread. A RH prop work exactly the same.

Yes.

But for our LH props (original Cox production from decades ago), that are stamped L.H., we still tighten the screw RH.

In no way implying that any of what has been stated in this thread is wrong but simply saying that we took over how Cox did this (and presumably other engine manufacturers in the past), in order to maintain continuity.

Admittedly, before we expressly clarified this on our listings, we did end up with some buyers getting the opposite of what they thought they were buying.

Cox International wrote:
It gets really interesting when someone inquires about a pusher-prop and we recommend a LH prop, mounted "hub-reversed" and run RH (to maintain leading / trailing edges). That's enough to even confuse us here.

Yes, that would indeed be very confusing as a LH screw/thread can never be turned into a RH one!

Surfer_kris wrote:

Cox International wrote:
It gets really interesting when someone inquires about a pusher-prop and we recommend a LH prop, mounted "hub-reversed" and run RH (to maintain leading / trailing edges). That's enough to even confuse us here.

Yes, that would indeed be very confusing as a LH screw/thread can never be turned into a RH one!

Not even by a skilled Swedish machinist?

I would never call screw threads by cw or ccw. But if someone asked me what direction that prop that's rotating in a large circle (almost like a clock face) is turning, I'd most definitely describe it as cw or ccw..that just me u understand. Been doing it like that for 55+ yrs. Hard teaching old dog new tricks....I guess

Cox International wrote:
However, as we cater to the Cox community, we adapted the Cox formula for rotation; whereas their starter cams are stamped "L" and "R" and some of their LH props are stamped "L.H."; basically as viewed from the cockpit.

L for a left-handed thread and R for right-handed thread is very clear, there can never be any confusion between the two.

The problem arrises when you start to talk about CW and CCW as seen from the cockpit.
In order for that to work you would have to clarify if the cockpit is behind or in front of prop...
Below is one example, should these props now be labeled differently just because the engines are behind the cockpit rather than in front of it?

Of coarse not, they are obviously RH props (and work just like a right-handed thread), independent on where the cockpit or the viewer happens to be positioned.  

Cox International wrote:
Not even by a skilled Swedish machinist?

Not while keeping the same diameter...

jbanes1961 wrote:I would never call screw threads by cw or ccw. But if someone asked me what direction that prop that's rotating in a large circle (almost like a clock face) is turning, I'd most definitely describe it as cw or ccw..that just me u understand. Been doing it like that for 55+ yrs. Hard teaching old dog new tricks....I guess

Yes, CW and CCW are definitely correct definitions but, IMO, the gist of the thread is from what side of the prop (behind or in front of it) this is determined.

Surfer_kris wrote:

Cox International wrote:
However, as we cater to the Cox community, we adapted the Cox formula for rotation; whereas their starter cams are stamped "L" and "R" and some of their LH props are stamped "L.H."; basically as viewed from the cockpit.

L for a left-handed thread and R for right-handed thread is very clear, there can never be any confusion between the two.

The problem arrises when you start to talk about CW and CCW as seen from the cockpit.
In order for that to work you would have to clarify if the cockpit is behind or in front of prop...
Below is one example, should these props now be labeled differently just because the engines are behind the cockpit rather than in front of it?

Of coarse not, they are obviously RH props (and work just like a right-handed thread), independent on where the cockpit or the viewer happens to be positioned.  

Excellent point:) Perhaps there is a better definition? I guess what we are trying to say is that we had to come up with a yardstick for OUR props and springs so that buyers choose correctly and we took over the (old-school) Cox labeling as we are purveyors of Cox products.

Perhaps we should acquire a quad for the office to really make our old heads spin

jbanes1961 wrote:But if someone asked me what direction that prop that's rotating in a large circle (almost like a clock face) is turning, I'd most definitely describe it as cw or ccw..that just me u understand.

I know that time sometimes "flies", but it is not actually going anywhere...

So which one would you use then?
CCW as in when you are flipping the prop to start the engine or CW as when you are "inside the cockpit" of a typical profile CL plane?  

If instead you think of the prop as an "air-screw", which it really is anyway, then all the confusion is gone.
This is also the old-school definition by Cox, so no problem there.

In order to explain or remember how a righthanded thread works one can easily use the right hand. Place the imaginary engine axis in the palm along the thumb and the other four fingers wrapped around the axis in the direction of the rotation. A righthanded airscrew (R or RH marking) will then travel in the direction that the thumb is pointing in.

And now my head is spinning! Lol. Time for a drink with my old pal Jack D. and rethink things again.

Since when do we modelers determine direction of prop rotation from behind the prop? That is just a confusion factor, that should not be mentioned here.

Regarding model airplane builders, our only consideration is which way to flip the prop for starting, or to spin it with a starter.

Prop labels can get a little confusing, but generally are not labeled with CCW or CW, and seldom if ever with RH, or LH.

Some shops label reverse pitch props "Pusher", because on normal CCW turning engines, they push a vehicle forward from the rear end of the engine and airplane. That was the original use for brass prop drivers, to minimize wear between the prop drive washer, and aluminum crankcase nose.

Bill