CEF speed contest Design Discussions

RknRusty wrote:Nice neat work, Roddie.
The weather is nice for the next few days until Tuesday, so tonight I'll get mine preflighted. I haven't cranked my engine in a couple of months, but what could go wrong, right. I'm going to try to fly it under the trees at the church yard, 42 foot lines in a 35 foot circle.  

  .....  ..... that's funny Rusty!!! The stories of contestants flights are something that should start pouring in.. in a week or so, and I will surely post my report. Today is "Time to make the 42 foot line-set" day. Once that's done.. the plan is to throw an engine in the old Cox Cosmic Wind and hope it simulates a flight at speed... just to get me used to turning circles again... and maybe a trial vid.

I still need to find a "secluded" site to fly... I'm looking for an inactive/abandoned industrial park lot.. where there won't be any danger of having a little kid wander over to take notice.

OVERLORD wrote:Well done Rémy, you're 1 step ahead.

After running my engine on a "test stand", I mounted it today on the plane for some trial runs. Because the engine is fully enclosed, I just wanted to get the hang of it: filing with fuel is through a tiny hole. It's also good to know if bits will fall or shake off. For the first time, I tested my ram air intake. Just before running the engine, the wooden bracket of the intake pipe fell of and I fixed it in emergency with an electric wire. The plastic inlet pipe is made of that same useless Bic pen that I used the ink tube of. The pipe that goes to the back of the engine mount is a lemonade straw. Here is a video I took while the engine was running.

https://www.youtube.com/watch?v=u1NzqJOa5I0&feature=youtu.be

Lieven

Congratulations to both of you... I haven't run my engine in my airplane yet. I'm having some strange issues with my needle floating... I mean; I can see it turning while the engine is running. I installed a small rubber grommet in the cowl that the needle shaft will pass through snugly.. which I'm hoping will cure that condition. There may also have been some vibration in my test stand's engine mount, which could have contributed to it.

I really like the look of that ram-air snorkel Lieven!!!

getback wrote:Roddie , that tank mount looks good wish u would have thought of that before I got mine mounted   I think I am going to start working on finding a better and easier way to mount the tank seems to be a on going problem with me rubber bands the right size with dowell mount sounds easy but I don't like the way it looks   

Hey Eric, There's a few alternate ways you could mount your tank.. but the dowels and rubber band method is going to give you the option of easily adjusting the tank angle. Looking at your P40Q photo (outboard view) I see small screw-eyes with wire attachment for your tank mount. You might be better off to remove those.. and move your tank forward; shortening-up the fuel line some. Is there room on your firewall to rotate the back-plate 90 degrees.. and drill a hole through the fuse for your needle shaft? As it is positioned currently.. the fuel in the line has to travel some distance.. and take an "S-turn"; down, in and up before it gets to the engine. Although this "may" work.. when you add the centrifugal force of high-speed flight into the equation.. there's a lot working against a reliable suction fuel flow there.

A good tank vibration insulator (along with a rubber-band mount..) is cutting a "pad" of the thin polyurethane filter-material that's used for window size air conditioners... (it's about 3/16" thick and very spongy) and put it in between your tank and the fuse. If you need to shim the rear of the tank.. it's just a matter of pulling the tank away from the fuse.. and sticking thin scraps of balsa between. The rubber-bands will hold it all in place.

As far as the "red high-flow back-plate" is concerned... (is that the one you are having trouble with?) I had my own share of difficulties getting that to run reliably on a suction/hard-tank arrangement... and I'm still not sure if I'm "out of the woods" yet... I had luck with increasing to a large size fuel line.. not larger.. LARGE! I accomplished that by cutting some short (1/4" long) sleeves of slightly smaller metal tubing.. and twisting the ends of the fuel-line into the sleeves.. which compresses the line down small enough to fit on the smaller nipples on the spray-bar and tank feed-tube. Combine this with a reliable seal on the needle... and you may have some luck. Also.. (something we can both try...) running an air-flow restrictor between the back-plate and firewall. I know this defeats the purpose somewhat.. of having a "high-flow" back-plate... but if you're running on "suction alone"... this will increase the air-flow's velocity while decreasing the volume... which may in combination; promote enough fuel draw.

If you think your reedie screams now?... put that red back-plate and the SPI Tee Dee cylinder/piston on it while trying those mods. When that connecting-rod broke on you, it was a fluke. Pick up a rod resetting tool if you don't have one already... and check the ball-socket fit regularly when running near or over 20K rpm's... and reset the fit if/when it feels loose. This is where rod failures usually happen.

no empty reel? improvise.

RknRusty wrote:

getback wrote:JIM I am sure some people have posted there entry videos ?? come on give us an idea of what kind of speed were up against ...rained today as Rusty said and back to the 50s will have to wait it out and hope the after storm wind want last long   Thanks Getback

Here's the thread, GB. No one has posted an official yet. I hope to fly mine Thursday. If not then Friday evening before the Sun sets, 6 hours before the deadline.

https://www.coxengineforum.com/t6567-cef-reed-speed-official-video-entries

Rusty

Don't forget.. you have to "PM" Jim with your official vid (using url code only). There shouldn't be any official flights on a public CEF thread yet. (see the OP in the above link)