VCox Pusher engine

Seems like I am always posting right after Phil! Sorry Phil, I don't do it on purpose.

Anyway all I can add is it's only the prop that makes it a pusher. The engine is no different than any other cox engine. Buy a tractor prop if you wish to run it the other way.

steve thornton wrote:Today I bought a Cox Pusher engine and prop.  I didn't notice that the prop was a pusher, just that the tips of the prop were swept on the ends.  My question is whether the engine runs clock wise or in the standard rotation?  Does it have a different crank or other parts?  It seems to be in good shape but is almost frozen, but I can fix that.  I have read the other threads regarding the Curtiss Pusher, but they didn't seem to address any tech questions.  Sorry I can't figure out how to attach a photo.  
Thanks for any input,
Steve

Hi Steve, Cox reed-valve induction engines will run in either direction because of their design.. unlike a rotary-valve induction engine. The reed is a thin membrane of Copper or Mylar located in the rear of the crankcase. It opens/closes with the vacuum/pressure created when the piston cycles through a stroke. It's held against a "seat" at the front of the venturi by a wire clip or retainer to limit its movement. Being "inside"; the engine must be disassembled to service it. Reeds are small and fragile.. but are replaceable. Yours may be "stuck" to its seat from congealed fuel. Disassembling the engine and soaking the parts in solvent/thinner should free it up. After soaking for a while; wipe dry and try (using your mouth) to blow and suck through the front to check it's operation. With the clip/retainer in place; it should "seal" (with resistance) when blowing.. and "open" when sucking. If not.. you'll need to carefully remove the clip and reed for further cleaning. It's helpful to put the parts in a clear plastic bag while removing the clip and reed. This helps prevent the loss of the small parts. The spring-wire clip/retainer can be removed with small needle-nose pliers. If the reed is stuck; try to "gently" lift it off the seat using a pointed razor-knife blade or a sewing needle. Metal reeds will bend/crease easily.. so be careful. More soaking is worth the time, rather than forcing it. Once removed; wipe the seat with a soft cloth soaked with thinner and check the reed for any "gunk" that may be stuck to it. Clean it using a cotton swab (Q-tip) with some thinner. Once cleaned; reinstall the reed and clip to check for proper operation before reassembly. While the engine/tank is disassembled.. it's probably a good idea to remove the needle-valve and flush out as well. Observe the free-flowing of solvent through the fuel pick-up line. These steps should ensure the proper flow of fuel/air into the crankcase. Final reassembly should be done using new venturi and crankcase gaskets if you have them. I use a little household oil on the parts when reassembling an engine. Tighten the four screws alternately in a criss-cross pattern until tight. Check your glowhead for glow.. (1.5V) and make sure you install the Copper gasket if you take it off. Finally; be sure to use good fresh fuel; like "Sig Champion 25" or the new Cox Superfuel blend by Hobbico. These fuels have an ample amount of castor oil, which is extremely important for your Cox engine's longevity.

Cribbs74 wrote:Seems like I am always posting right after Phil! Sorry Phil, I don't do it on purpose.

Anyway all I can add is it's only the prop that makes it a pusher. The engine is no different than any other cox engine. Buy a tractor prop if you wish to run it the other way.

Unless I'm mentally blind (could well be so) can't he simply remove the prop, turn it over (ie have the opposite face of the hub against the thrust plate) and then spin it the other direction to have a tractor prop? When I get home I'll try it for myself.

dinsdale wrote:

Cribbs74 wrote:Seems like I am always posting right after Phil! Sorry Phil, I don't do it on purpose.

Anyway all I can add is it's only the prop that makes it a pusher. The engine is no different than any other cox engine. Buy a tractor prop if you wish to run it the other way.

Unless I'm mentally blind (could well be so) can't he simply remove the prop, turn it over (ie have the opposite face of the hub against the thrust plate) and then spin it the other direction to have a tractor prop?  When I get home I'll try it for myself.

Yes, please try that yourself. (The following will probably make more sense if you do try it yourself though)

It does work for using the same prop on a pusher engine setup, but the engine gets turned around and run the other way...sort like tightening nuts on a bicycle tire (or a continuous threaded rod). The threads are the same, which is how the prop acts whether it is facing forward or not, but the direction you turn the nut changes with the frame of reference. The desired direction of travel changes.

The prop however wants to have the curved side forward and the flat side backwards to operate properly. Reversing the prop is a classic way to de-power a setup.

Phil

Ok I have heard this TRACTOR prop talk and don't know what the heck Y'all are talking about so some one clue me , Please

getback wrote:Ok I have heard this TRACTOR prop talk and don't know what the heck Y'all are talking about so some one clue me , Please

"Tractor" just means a prop that pulls, where a pusher pushes (obviously)

Nothing to do with tractors.

Mark Boesen wrote:

OK what kind of prop is that I have some of them Thanks Rod

It was made for the 1911 Curtis, i don't recall the specs, i'll guess and say 6x3, i don't think its the same as the props made for the WWI series, those has a smaller diameter?

I think that Pusher mostly refers to the location of the produced-thrust in relation to the airframe. Keep in mind that some propellers designed for a pusher app. may have their hub finished on the front-side, to properly bear on the drive-plate of the rearward-facing engine. (the radially-splined face).

The Cox reed-valve engine is really a marvel, in that it can run in either direction. I think of them as the "all-purpose" engines of their size/group. Not high-performance by design, but can be hopped-up... which is fun to mess with! The "Ace-style" venturi-throttle for the Bee engines, that Cox International sells; works very well in my experience. I've used that throttle on my Cox Babe Bee engines.. and get about a 10K range in rpm using a 6 x 3 prop. Idle-speeds below 3k are possible; providing a good base-running engine and keeping the head hot. A muffler is recommended.. and I made my own minimally-restrictive design that I use when bench-running. A cowl'd-in aircraft app. would help keep the engine hot too. The high-nitro fuel for these engines; in my understanding.. has a "cooling" element.. as well as a combustion enhancer. We've seen the Cox Babe Bee .049 used in numerous Cox RTE (Ready To Enjoy) models.. many of which don't have the cooling-element of an open-cowl aircraft application. Some engines are buried in a floor-pan.. turning a screw-drive with little cooling at all.. maybe a heat-sink like the popular Sandblaster had. The engines just kept running.. reliably on their Cox Super-Power or Racing-blend fuels. Quite a success story.

Sorry to roller-coaster here..

I think any reed valve engine will/can run any direction I have had a dirt bike back fire and run backwards = it or I didn't like it though