CEF speed contest Design Discussions

opps, 30% is max nitro,

GUS THE I.A. wrote:Yep, I'm not gonna go fancy on the fuel. Just the stuff from the COX bottle is what I use.

Not the Tower Cox fuel I hope... unless you're seriously spiking it. It's 90% synthetic/10% castor. Instant overheat and ruination for Cox engines.

Rusty

I've never blended model fuel.. and didn't plan on having to buy any. When the rules were set for 30%.. I just figured I'd use an un-opened bottle of 25% that I have. If Nitro % is raised to 35, I'd definitely consider getting a fresh quart of Sig 35% fuel.

A good U.S. LHS  may have Sig 35% in pints, as they are available through Sig. MSRP $8.24 (Sig lists them on their site as "avail. for" $5.49... cheap; if you're combining shipping with a "Skyray" or some other 1/2A kit)

see Sig's site link (*** search catalog for: field equipment/fuel/airplane/Sig Champion fuel, where you'll find details and prices)

http://www.sigmfg.com/cgi-bin/dpsmart.exe/IndexAboutSigCatF.html?E+Sig

Roddie

I guess for the sake if avoiding confusion lets keep it at 30%. Sorry for stirring the pot guys.

Jim

Okay, all you balsa bashers, tell me this: Now that I finally have my wing drawn up at 15.5" span and 47.1 squares, I need to know where to put it. How do you locate your wing? I suppose TLAR is fine, but is there a sweet spot at which the mean chord (or LE or something else) should be located between the nose and tail?

Rusty

JPvelo wrote:I guess for the sake if avoiding confusion lets keep it at 30%. Sorry for stirring the pot guys.

Jim

Would it be feasable to say a max of 30 percent? That way we could choose to use less if we want.

Cribbs74 wrote:

JPvelo wrote:I guess for the sake if avoiding confusion lets keep it at 30%. Sorry for stirring the pot guys.

Jim

Would it be feasable to say a max of 30 percent?  That way we could choose to use less if we want.

Yes, that's how the rule reads.

RknRusty wrote:Okay, all you balsa bashers, tell me this: Now that I finally have my wing drawn up at 15.5" span and 47.1 squares, I need to know where to put it. How do you locate your wing? I suppose TLAR is fine, but is there a sweet spot at which the mean chord (or LE or something else) should be located between the nose and tail?

Rusty

I tried to locate mine as close as possible to the scale location.

Jim

JPvelo wrote:

RknRusty wrote:Okay, all you balsa bashers, tell me this: Now that I finally have my wing drawn up at 15.5" span and 47.1 squares, I need to know where to put it. How do you locate your wing? I suppose TLAR is fine, but is there a sweet spot at which the mean chord (or LE or something else) should be located between the nose and tail?

Rusty

I tried to locate mine as close as possible to the scale location.

Jim

That's what I'll do too. I know y'all probably roll your eyes when I ask stuff like this, and I don't fret over it as much as you might guess, it's just a learning opportunity, and I can't help wanting to know. Designing a simple slat winger from scratch, as did Carl Goldberg, Walt Musciano, et al., to come up with a quality flying machine that anyone can glue together and fly, is much more of an undertaking than meets the casual eye. My brain has been fried from medical bullets and can no longer follow the engineering details when I try to read up on it, however conceptual information is still clear as a bell and i can retain it. My curiosity seems to still be intact.

Goofy Rusty

Hi, some news about my Polecat,




Some work must be done before the maiden flight,

Looks good, Navion. I hope to start cutting wood for mine in a couple of weeks while the paint on my Yak cures. I'm tired of talking about it and ready to start doing it.

Rusty

RknRusty wrote:. Designing a simple slat winger from scratch, as did Carl Goldberg, Walt Musciano, et al., to come up with a quality flying machine that anyone can glue together and fly, is much more of an undertaking than meets the casual eye.

Goofy Rusty

Yeah, my corsair took far more work than I imagined. With all the angles I ended making five wing panels and six cheek  blocks. The angles on the cheek blocks where they sandwich the wing were a mutha to wrap my mind around.

Jim

navion34 wrote:Hi, some news about my Polecat,




Some work must be done before the maiden flight,

Looks real good, can't wait to see it done.

Jim

Smart plane Rémy.

I made a new wing in 2 halves with the idea glueing them together with some dihedral. I sanded the wing to obtain an airfoil shape but I don't know if this shape is any good or how it should look like ideally.









Lieven

http://airfoiltools.com/plotter/index

be prepared for information overload.

OVERLORD wrote:I made a new wing in 2 halves with the idea glueing them together with some dihedral. I sanded the wing to obtain an airfoil shape but I don't know if this shape is any good or how it should look like ideally.
Lieven

You're much more dedicated than I am. Flat plate was good enough for me. Sanding an airfoil into the wing for this was just too much tedium.

The ADD Mark

Hi Lieven, fantastic job !!!

If you want to shape a profil, be careful, make the two wings identical...

I hope to see this Caudron one day,

Rémy

I did a little tank fitting today. Not sure if I mentioned; the x4 bodies and end-caps were formed using a .750" x .5" bar of aluminum and a plastic head hammer. The bodies/end-caps are .008 Tin-sheet and are 1.25" long. This works out to a capacity of .26 ounces or 7.7 cc's. This version is standard design open-interior uni-flow and fill tube (to be capped, once fueled) Another will have a slightly forward uni-flow position, and the last 2 will have experimental "windage-tray" panels with drainage slots. These will slide in diagonally/lengthwise and will not be soldered.

The tank will be in a position resembling the full-scale F8F-2's bright metal exhaust shields. I made a tin-sheet "dummy" panel for the inboard side. It's thin, lightweight and inside the cowl's wake... just as the tank is.. on the outboard side.

I'll post more pics when they're soldered-up.

Roddie

These are 2 slightly different windage panels that slide-in diagonally, as an experiment to keep the fuel stabilized at the rear lower outboard quadrant of the tank, where the pick-up tube and uni-flow vent do their job. They are made from .005" sheet-Brass, cut to size w/scissors. A hand-type hole-punch was used on the panel edges.. although I'm not sure that these "reliefs" are necessary.

Time will tell... that's what makes this contest so much fun. I tend to be analytical...    I think I mentioned in an earlier post, that it would be interesting to test-run these models "round-the-pole" with a fixed neutral elevator on real short lines...  
cannibalize your round pool cover for a smooth padded runway over grass, with an anchor in the middle!!   keep a bat of Owens-Corning insulation nearby to toss-in and stop the model if things go awry...   If your engine runs through a tank of fuel... you'll know your fuel system is bullet-proof!   

just adding a little humor... life's too short.

Roddie

Roddie you remind me of myself(mostly my earlier self), only more sophisticated in your ideas and products. I'm interested to see a comparison between tanks with and without the windage trays. The brass will turn green after a period of disuse, but can be flushed clean with brake cleaner.

First clear day I'll fly the muffler on my Tee Dee. Tomorrow I have to wet vac my flooded shop. I just went to get pizza out of the freezer and it's friggin' soggy mess out there.

Rusty

My tank experiments have included the same baffle that Veco used within their tanks. I learned that the tank has worked equally as well without it. The baffle also provided a place for more corrosion to form within the tank. It becomes extremely difficult to remove the flux. I've since switched the style of flux I use as Stay Bright is very corrosive if not quickly dealt with. The fuel load isn't sloshing all over as one would think. The funny things about tanks are that I've found plastic tanks to be the most successful. I don't always set them up with the clunk as some of them are hard piped. These tanks seem to work flawlessly not to mention they use just about every bit of fuel. That being said, there's no baffle within them. Ken

Ken Cook wrote:           ...I've found plastic tanks to be the most successful. I don't always set them up with the clunk as some of them are hard piped. These tanks seem to work flawlessly not to mention they use just about every bit of fuel. That being said, there's no baffle within them. Ken

I'm glad to hear something good about plastic tanks. After Ray Copeland gave me the Skyray with a Sullivan clunk tank, I've had the most dependable runs ever with muffler pressure to the uniflow vent. And after a day of flying, there's almost no fuel to draw out of it, maybe a cc at most. I do use the clunk. But since recounting my good experiences to the guys in my club(I have joined the MCLS Huntersville gang), and on the stunt forum, all I hear is how they are undependable and no good. Leaky stoppers and develop cracks. So, wtf, they're cheap, I'll replace any one that goes bad. My only gripe is that they are ugly.

Rusty

I agree... Very ugly, but the ones I have seen always work well.