CEF speed contest Design Discussions

I made one more tank to try. This one is tall/thin and works out to 6.15cc's capacity.


It measures .250" wide x 1" tall x 1.5" long.


uni-flow venting like the others I made.





The paint's gonna' be tacky on this thing come the 31st... if I don't get my butt in gear soon!!!

Well, parts are starting to trickle in for my build. My late discovery/participation of this challenge is starting to hit home. I'm gonna give 'er a shot to get finished but....

I need to get some flying lines. I searched around and found you guys like Spectra and such in the lighter 10-15-20 weights but dont see what weight line I should use for speed flying.

Mike

Hi Mike
Don't worry, I'm just getting started too. Maybe we won't have time enough to overthink it into a kludge.  
I think I'll try some of the 10 pound line. I have some .008 steel too, but have never flown 1/2A on steel, so I don't know which is best. I'd say for those of us that are raw novices at speed... like me, this is the least of our problems, so just get what you think you can work with the easiest.
Rusty

While I've flown on .008's for a long time, I switched to .012's due to many line failures. They're just too fragile and there really isn't that much of a drag penalty using .012's vs. .008's. .008's work fine for stunt, but I suggest .012's for speed. They're not going to kink as bad and they just hold up far superior. Ken

RknRusty wrote:Hi Mike
Don't worry, I'm just getting started too. Maybe we won't have time enough to overthink it into a kludge.  
I think I'll try some of the 10 pound line. I have some .008 steel too, but have never flown 1/2A on steel, can work with the easiest.
Rusty

I agree, lack of time solves a lot of decisions. I just ordered a roll of 10 and 15 pound spectra off Amazon along with some other items I needed. One of those hopefully will work. I'd try to get some metal lines in but I'm tired of ordering stuff. Its sobering how much you need for a simple 1/2A when starting completely from scratch.

Mike

Finally getting some more painting done. Have you ever had a rattle-can that leaked like a sieve around the base of the valve.. dripping paint down the side of the can, all over your fingers and onto the floor? Welcome to my world.   



Because I was a dummy.. and hinged my elevator prematurely.. I had to lay 2 pcs. of .031 music-wire along the hinge line and remove them after spraying..   

Some Vaseline on a toothpick might have worked too.
Rusty

Looks good Roddie!

  Looking good there Roddie ,Man you put that together quick    Got mine painted yesterday took about an 1.5 hour outside I am happy with it though have to do alittle touch up here and there , PIC not ....Eric 

Ok,

Here it is minus landing gear and control linkage. It weighs 4.6oz as it sits. Not sure if low weight is desirable or not?

Cribbs74 wrote:Ok,

Here it is minus landing gear and control linkage. It weighs 4.6oz as it sits. Not sure if low weight is desirable or not?

Nice Ron!!! and also nice to see a hard-tank on it! If having lightweight is an advantage... I'm in trouble there. I'm a full 2oz. heavier than you.. and one ounce heavier than either of Jim's models. I built my Bearcat with it's proportions by "eye" and it's got a lot of wing and fuse area. The 17" span wing is just over 70 squares with a 6" root chord, tapering down to 2" at the tips.. no dihedral and is dead-flat 1/8" sheet balsa. The 1/4" balsa sheet fuse is almost 3.5" tall between the belly and the top of the canopy. I'm surprised that it doesn't weigh more than it does.

Have you figured outboard wingtip weight in yet? I didn't see a tip-weight in your photo.. unless you used a heavier outboard wing strut? That would be a neat way to accomplish it on a bipe. I was thinking .010" Brass sheet.

roddie wrote:...If having lightweight is an advantage... I'm in trouble there. I'm a full 2oz. heavier than you.. and one ounce heavier than either of Jim's models. I built my Bearcat with it's proportions by "eye" and it's got a lot of wing and fuse area. The 17" span wing is just over 70 squares with a 6" root chord, tapering down to 2" at the tips.. no dihedral and is dead-flat 1/8" sheet balsa. The 1/4" balsa sheet fuse is almost 3.5" tall between the belly and the top of the canopy. I'm surprised that it doesn't weigh more than it does.

Have you figured outboard wingtip weight in yet? I didn't see a tip-weight in your photo.. unless you used a heavier outboard wing strut? That would be a neat way to accomplish it on a bipe. I was thinking .010" Brass sheet.

Here's where most of us guys are out of our area. At first I was thinking radically light. a butterfly with an engine. But I was overlooking the advantage of whipping up inertia for several reasons, one being penetrating the wind, and also resisting floating. That second part also speaks to the wing area, of which less is best. A flying knife is probably what we want. I think I have a good wing if it's not too wide at the root, about 47 squares and 2" tips. I don't know for sure, but it seems like more tip weight might be helpful here.

I haven't got but a couple of hours into this thing. My wing location is adjustable like those toy gliders we played with decades ago, and will be the last thing glued in place. It's been sitting ignored for two weeks now, so time is rushing up on me.

I'm going to laminate the stab/elevator to encase a gapless hinge. What you see here weighs about nothing. It may be too light.

C'mon Rusty, you have plenty of time. A full week from today if I'm not mistaken!

Jim

JPvelo wrote:C'mon Rusty, you have plenty of time. A full week from today if I'm not mistaken!

Jim

Oh don't worry, I'll get it in under the wire. Even if it kills me, tomorrow is the last day I'm working on the Yak. That was supposed to be yesterday but nothing I did worked. Just one of those days. Tomorrow is gonna be a great day!

Rusty

hey Rusty ( and everybody) i'm in the same boat, dragging my feet on this project as well, now i'm thinking since I got the wing and fuselage cut for a mustang to just go ahead and finish it, forget about the shoestring. i'm off Tuesday and its only gonna hit 27, so I think i'll pass on disc golf and do some building...I remember as a kid we could slap together a 1/2a kit in an afternoon (it probably looked like it) so I really think 2-3 evenings should be good.

roddie wrote:

Cribbs74 wrote:Ok,

Here it is minus landing gear and control linkage. It weighs 4.6oz as it sits. Not sure if low weight is desirable or not?

Nice Ron!!! and also nice to see a hard-tank on it! If having lightweight is an advantage... I'm in trouble there. I'm a full 2oz. heavier than you.. and one ounce heavier than either of Jim's models. I built my Bearcat with it's proportions by "eye" and it's got a lot of wing and fuse area. The 17" span wing is just over 70 squares with a 6" root chord, tapering down to 2" at the tips.. no dihedral and is dead-flat 1/8" sheet balsa. The 1/4" balsa sheet fuse is almost 3.5" tall between the belly and the top of the canopy. I'm surprised that it doesn't weigh more than it does.

Have you figured outboard wingtip weight in yet? I didn't see a tip-weight in your photo.. unless you used a heavier outboard wing strut? That would be a neat way to accomplish it on a bipe. I was thinking .010" Brass sheet.

I plan on using a penny as tip weight.

As to the hard tank, I figured this is nothing like stunt so I wasn't too concerned about all the fuel delivery issues you experience in PA. Hopefully it works for 10 laps.

Ron

Mark Boesen wrote:hey Rusty ( and everybody) i'm in the same boat, dragging my feet on this project as well, now i'm thinking since I got the wing and fuselage cut for a mustang to just go ahead and finish it, forget about the shoestring. i'm off Tuesday and its only gonna hit 27, so I think i'll pass on disc golf and do some building...I remember as a kid we could slap together a 1/2a kit in an afternoon (it probably looked like it) so I really think 2-3 evenings should be good.

Yes! Can Do! Will Do. We are master balsa builders. If I have to bolt a motor on a stick, I'll make the finish line!

yep, it's go time!

Cribbs74 wrote:
I plan on using a penny as tip weight.

Ron

I have never flown with lines this long, so I feel that a little more tip-weight than usual, might be needed to level-off the little model while it's hanging way out there. I am shooting for 5gr. The sheet-Brass tip-weight in the photo is .005" thick.. but only weighs 3gr... so I may make a second one for mounting them top/bottom. I'm using 2-sided adhesive/super-thin laminating film for attachment to the wing-tip.

I've got gear! Thanks Rusty!

5 separate pieces to make it up. I think I'll skip the pants and go commando...

All that's left is the tail skid, tip weight and the little triangle gear covers, they have a proper name, but it alludes me at the moment.

Hey that's pretty cool. See, it looks fine after all.
Rusty