cox 049 endurance record?

JPvelo wrote:I agree with Roddie, simple is better.

Yes.. and I hope that this gathers more interest. Perhaps the event should be re-named with "duration" being the key element.. rather than endurance. It is a test of both though.. except we'd be lifting an airframe.. not running an engine on a test-stand.

How could this commence? Some research on airfoils and high-wing designs would be a good place to start. Actually; reading through info in the below web-link, will no-doubt help you to understand the concept.

http://www.charleslindbergh.com/history/sec/

Secondly.. researching the lightest-weight materials for the entire aircraft. A 41" wing-span, I believe would make a 1" scale subject if you were to build a scale-model Ryan M1. (I need to read more) There are PDF downloads available of the original airplane. Whether that scaling is the way to proceed depends totally on the entire design. Some interested modelers may choose to go with a more modern design. It doesn't really matter.. because someone will have an airplane that's able to fly for a longer period of time!

Years ago.. I put some thought into RTP (round the pole..) control-line flight, that involved building a center-circle fixture to replace the pilots' needing to turn with the model. It involved a fixed-line and naturally the other being movable. A "yoke" would need to be designed to make this possible. A level-only flight-path would simplify such a system.. with offsets built-into the model to help maintain line-tension while flying in calm-weather conditions. The models' extra fuel-weight would help early-on with the flight.. given centrifugal-forces, but once fuel-weight is consumed, the model must still be controllable. Relief-pilots would be fine too.. but it would be great to control/observe the flight from outside the circle.. especially if your design is capable of flying for several; 5,10,15 or more minutes! Scale-mileage could be calculated by your line-length too! There's a lot of plusses to a an event such as this. Any one of us could have our own little place marked in the Cox-engine/powered-model record-books!

I had a TD on a Brodak 1/2A Pathfinder which would easily do the full pattern and more. I could achieve 10-12 minute flights without even blinking an eye. If your looking for endurance, set the time high. 15 minutes is nothing in terms of endurance.

No kidding. I'm not going to say what I'd build, but I promise you I can take a Snickers or two out there with a lawn chair and put up a flight that will be competitive.

Is it going to be any Cox .049?
Rusty

RknRusty wrote:
Is it going to be any Cox .049?

Rusty

I's say yes to that.. (and maybe the .051 too..) Modify it any way you like.. but I wouldn't go for any high-power mods. I don't know what size the venturi-diameter is on the Texaco reed-valve engine. Is it the standard Bee's .062"? Maybe clone a Texaco-configured engine.. and compare the bench-run times/fuel-consumption with a standard Bee using the same conditions/variables.. (prop/fuel/temp.. etc.) You can drill a hole in the side of an old spare 5cc tank and run your feed-line through it for connecting to a larger fuel tank. The postage-stamp and horseshoe backplates would be easier to run a fuel-line to a large tank.. but have larger venturis than the Bee-engines.. therefore, they might not be an economical choice for fuel-economy.

I doubt that a rotary-valve engine will achieve the economy of a reed-valve.. but who knows? Maybe a Medallion could? It would probably be an advantage to use a fine-thread NVA where possible.

After a little research.. it seems that the Cox Texaco (8cc tank)/Texaco Jr. (5cc tank..) do have a smaller venturi than that of the standard Bee engine's .062" size. How much smaller I don't know. Cox International (Bernie) or EX Model engines (Matt) could tell us for sure.

Maybe one could experiment with an old spare Zamac Bee backplate.. by reducing the outer air-intake diameter. One way to do this would be to drill some smaller "subject-diameter" holes (.050", .047" etc.)  near the edge of a sheet of .005" sheet-brass and pop-out a disc using a standard paper hole-punch, then attach/glue the disc on-center over the backplate screen. There are other ways to do it.. but you need to be mindful not to close-off the needle-valve's spray-hole if for instance; you choose to "fill" the backplate's air-hole, then drill-out the filler material.

I also looked through the CEF "Cox Cylinder Identification" page.. HERE.. and it appears that the Texaco engine does not use any unique "porting" in its cylinder. There wasn't a cylinder "number" listed that was specific to the Texaco engine either.

So.. if one wanted to configure a Texaco "clone" engine; they'd need to start by providing/making the correct size air-intake, obtaining a correctly-ported cylinder, obtaining a 5-fin glow-head, a 7" x 3.5" prop.. and a freshly re-set ball/socket joint on the piston/rod. As far as "fuel" is concerned.. that's anybody's guess.  

Here's some really cool info I found when searching Cox Texaco Fuel through Google. It naturally deals with "Free-Flight".. but provides some VERY interesting info on how one man and his dad set up their engines/airplanes, model-weights, fuel/props used.  

http://scamps.homestead.com/Texaco_Secrets.pdf

For any member that doesn't want to spin around - it can be remote controlled and still be "control line"



To take into account any wind and keep the lines taught



Dieselise the engine and reduce the venturi size - should yield 40 - 50% increase in engine run time.