Tanks, anyway...

[Steve Helmick]

My SV-11 with PA .51 had only a nominal 6 oz commercial uniflow tank. It wasn't enough to reliably get in the whole pattern, unless the weather was pretty hot. Last week, I added a "sump" to the bottom of the tank and increased the capacity to 7.5 oz. as measured with real fuel, and a 5 oz syringe, while in the plane, sitting on the wheels. As expected, there was no change required in tank height setting.

As a result, I was a happy camper, except that I didn't get a practise flight in at NW CL Regionals, and had to just go for it. I pulled out 1 oz after filling, resulting in running out of fuel in the first loop of the Clover, whipping 2 lap and landing. Got 10 for the Clover and no PP's. Next round, I pulled out 1/2 oz and got a complete flight, 481 points, and 4th in Advanced. Got beat out of 2nd in the last four flights. Ah, well, less dusting to do, and nobody suggested that I move up to Expert! Brian Massey told me my plane was doing 5.5 sec. laps, which we seldom check. It was a little slower than normal. And one of the judges walked over and asked what my pipe length was, 'cause it sounded really good. Had fun, too.

Got home about 3am. Traffic was fairly light, due to my late start from Eugene.  I'll do that again, I hope.  Steve
 

[john e. holliday]

Sounds like you are getting the better of it.  Also fourth is not bad with the caliber of people flying up there.

[Paul Taylor]

Way cool Steve!

No pictures of the sump?

And what about some pics of the plane with the cool sounding pipe?

[Steve Helmick]

Way cool Steve!

No pictures of the sump?

And what about some pics of the plane with the cool sounding pipe?

No pictures of this tank, EVER! The solder job is ugly. Used two different soldering irons, neither of which wowed me. The 80 watt "stick" one I've posted pictures of worked better than my 350 watt Weller gun. I think because the tip was just too small on the gun. But sometimes it seemed like it (the 80 watt stick) shut off and didn't maintain heat. I got good hot joints, but found a leak in a corner and decided to go over all the seams to get a uniform appearance. It just got worse looking, but the seams are still viable. I'll look for a better soldering iron...

I was very pleased with the fits of the sump details, and the sump itself onto the main tank, which is much of the battle. All joints are lapped or flanged. All are "internal", except the one that fairs into the "wedge" of the tank. Cutting out the bottom of the tank was handily done with a Dremel abrasive disc. I drilled 1/8" holes in the corners of the cutout, and just connected the holes. A bit of filing to make it all neat, and then the sump went on.

It wasn't the pipe that sounded cool....it was the way the engine was running. It does a nice yob of controlling the diving speed, and really cranks out the suds when it is needed in the climbs and overheads. Since this is my first pipe model...and I was NOT going to run pipes...I am thoroughly impressed. I wish I could figure out the starting drill, but I can't seem to get it wet enough. Arrrrgh!   

The point I wanted to make with this post is that as long as the fuel feed and uniflow pipe (inside the tank) remain in the same location, the rest of the tank volume's location matters not. Add sumps, bumps, and warts as you see fit.  Steve

[Brett Buck]

No pictures of this tank, EVER! The solder job is ugly. Used two different soldering irons, neither of which wowed me. The 80 watt "stick" one I've posted pictures of worked better than my 350 watt Weller gun. I think because the tip was just too small on the gun.

  Tighten the screws on the Weller tip. Mine needs that regularly. The size of the tip makes almost no difference when you are throwing the entire 350 watts into it. I get almost instant liquid solder with 260.

    Brett

[Bill Little]

Hi Steve,

Sounds great!  Where did you locate the "sump" portion in relation to the overall tank?

Big Bear

[Bootlegger]

   Yeah, where is the sump???   Show pitchers PLEASE, all of us do BAD solder jobs also, so don't let that discourage you...
   
   I am wit Bill Little AKA Big Bear...    

[Russell Shaffer]

Try painting it.  That way it blends with the fuselage and looks better no matter how good the solder.  If that's still not good enough, just tell people that Russell did the work.

[Mark Scarborough]

Russell,
its buried inside the nose on Steves plane,, he dont need to paint it, LOL
Steve, you got me by a few points,, despite some rather frustrating issues , one of which I preach about constantly,, that being have a back up prop that WORKS on your model, I felt I came back on my last flight and made a decent flight. That one judge was brutal dontcha think?
wish I could have watched more flights but I was busy trying to find a reasonable prop for the Avenger,, Karma pays off, the new prop is even better than the one I lost to a line clip,,
FWIW< NO I did not have the handle or lines reversed,,

[Steve Helmick]

"That one judge was brutal"...yeah, but consistently brutal to everyone. Can't ask for more than that. It is an ego crusher, however. I doubt you have experience flying in front of that particular judge before. Remember the old saying: "Sticks and stones may break my bones...but whips and chains excite me!"  Now you're excited!

Mark, I still wish you'd 86 the McMahon clips. From my 'sperience, they are much more likely to do the "twist & jam" trick that bit you.  A lot of those are brass, and not as strong as you would think. I did see some of the old style dogbone clips with the little folded sheetmetal slider/locker at Regionals. I was a bit horrified, actually.   I can't speak for PW and Howard, but the rest of us over here use the Sullivan "paperclip" type, or make our own clones. The SV-11 has to take a 45 lb pulltest, and they do that just fine.  I got a batch from Tower Hobby a few weeks ago, to replenish my supply of the stock length ones. I can make clips of random lengths myself, using the Derek Moran clip jig from Jim Lee Machine. Making a bunch all exactly the same is a bit more of a challenge.

Thanks to Brett for the hint to tighten the screws that fasten in the tip on the Weller. I'll give that a try. I don't think the tip is the correct one for that gun. Maybe that's the problem. I'll see if I can locate the correct tip online.

Russell's idea is also not a bad one. Some work with a Vixen file, some Bondo, 3 coats of 2-part primer, wet sanded, and a nice coat of pearl metalflake candy mango plus two coats of clear coat...nah!  But thanks for the idea....Russell did all the soldering for me. Thanks, Bud!    Steve 

[john e. holliday]

People complain about judges, but they need to do it once in a while.   I don't care how a judge scores if he is consistent.  My only 500+ score was a new judge in St Louis a few years ago.  But, from what I heard and saw he was consistant.  Nothing like switching judges between rounds either.  Everybody that day thought I had put in my best flight in the second round.  Went from 1st place to 4th place.   Yes I was upset as I watched the flights of my competition.   Guess I should have kept my level flights at 10-15 feet.  Now I could care less as I started having fun and don't want to get serious anymore.   

[Mark Scarborough]

Lest it be misconstrued, I was not bashing the judges, simply commenting that there was a wide gap between the two judges. I was to busy to make a comparison on how consistant she was. I do know she is supposed to be consistant, and thats all you can ask for, the actual numbers arent as important as a level playing field.
@Steve, the clips, well I have not had problems, WHEN I DO MY JOB and walk the lines out, for some reason this flight I did not. As to the other clips, I have a clip tool, and dont like it, the pins are situated such that you cannot clamp the tool in a vise, no flats to work from. One day I will make my own and then it will be fat city, I too can have a collection of clips to rival Dirt's

@ Doc, I have judged, It is an eye opener to do, I dont mind it to much, but would be much more comfortable with some hands on training though instead of just being thrown to the wolves as it was......

[john e. holliday]

Well I sympathize with you.  I have been to contests where the judges have not had much training.  Now the clip maker I use is made by Carl Shoup.   The same guy that sell the Fancher Handle kits.  I will send a PM with address.

[Tim Wescott]

  Tighten the screws on the Weller tip. Mine needs that regularly. The size of the tip makes almost no difference when you are throwing the entire 350 watts into it. I get almost instant liquid solder with 260.

Check the cleanliness of the tip where it goes into the prongs on the body of the gun, and possibly the body as well.  The heat makes everything corrode much faster than normal, and corrosion doesn't carry current the way metal does.  If it doesn't look like it's making metal to metal contact, sand or file until shiny, or put a new tip in.

[Steve Helmick]

Well, I found that I'd taken pictures (and f'got!) of the tank midway through the rework/butchery. So, to satisfy a few curious folks, here 'tis. I should have moved it back some, 'cause it's quite close to the header at the front corner. But it does work just fine, and (again!) no shimming changes were required.

Thoughts on the tank: This particular commercial tank (dunno if it's a Brodak or GRW/RSM) was well made, but the overflow tube was (still is) so far from the top of the tank, there's no way you can actually fill it completely full of fuel. I was thinking of putting a new overflow in it that would tuck into a dome sort of deal on the top of the tank, to allow really filling it full. This would perhaps have done the trick, and would be a lot simpler modification to do. I was thinking about using a cap for copper tubing from the plumbing supply store. In this case, I would have had to auger into the airplane to make room for the dome thang.    Steve

PS: Shoulda used a tripod. But then, I really didn't want the pics to show all the goobers...

Edit: The tube on the fa' side with the silicon tubing is the overflow vent. The nekkid one is the uniflow, and of course the one with the filter feeds the NV. Just in case somebody has a tank like this and is wondering which outlet is what.

[Brian Massey]

Thoughts on the tank: This particular commercial tank (dunno if it's a Brodak or GSW/RSM) was well made, but the overflow tube was (still is) so far from the top of the tank, there's no way you can actually fill it completely full of fuel. I was thinking of putting a new overflow in it that would tuck into a dome sort of deal on the top of the tank, to allow really filling it full.     Steve

Steve; years ago (like 40) I had a similar problem with an overflow tube. I removed the tube, drilled small hole where the tube should end, then soldered the little metal cap from an now old fashion fuse over the hole. Then replaced the tube with one slightly longer, and with a bevel on the end so it could extend into the cap. Worked great.

Your tank looks really good by the way.

Brian

[Steve Helmick]

"Your tank looks really good by the way.  Brian"

That's B.S.!  Before Solder, that is. Well, the sump ends were already soldered in. The fuse end cap would work. Maybe somebody has an idear (watched OCC yesterday) that wouldn't weigh so much?  Steve

[Brian Massey]

"Your tank looks really good by the way.  Brian"

That's B.S.!  Before Solder, that is. Well, the sump ends were already soldered in. The fuse end cap would work. Maybe somebody has an idear (watched OCC yesterday) that wouldn't weigh so much?  Steve

Just smear a little Spicy Brown Mustard on the solder joints; it'll look great! 
Brian

[john e. holliday]

In the days of crankcase pressure tanks, I used the lids off the pint cans.  Put pressure tube up into it.  Also isn't it where the pick up tube tube located more important than the mass of fuel in relation to the engine needle valve assembly?

[Steve Helmick]

"In the days of crankcase pressure tanks, I used the lids off the pint cans.  Put pressure tube up into it."

Yup, same idea, but for the overflow. Looking for something a lot smaller and lighter. Smaller than a thimble by at least 50%.  

Also isn't it where the pick up tube tube located more important than the mass of fuel in relation to the engine needle valve assembly?

Actually, not quite. What counts mostly (with a uniflow tank) is the location of the inside end of the uniflow tube, and the NV Assy. apparently has nothing to do with it. Strange, huh? But I'm pretty sure that's what you meant, Doc.   Steve

[Brett Buck]

Well, I found that I'd taken pictures (and f'got!) of the tank midway through the rework/butchery. So, to satisfy a few curious folks, here 'tis.

    That's quite an impressive hole you cut, there. I probably would have just poked a few strategically-placed holes, just enough to let fuel in and to ensure it could get out.

     Brett

[Tim Wescott]

That's quite an impressive hole you cut, there. I probably would have just poked a few strategically-placed holes, just enough to let fuel in and to ensure it could get out.

-- and you can call it an anti-slosh baffle if anyone accuses you of being lazy.

[Steve Helmick]

Well, that's just me. If it's not functional, I get rid of it. And, like setting up a mill or lathe project, a good setup is good insurance that you don't have to do it over, or get bit in the butt. Besides, the weight I got rid of helps a little to make up for all the Xs solder.     I designed the outboard flange of the sump so it would fair into the tank's wedge, to make sure the fuel would flow out of the tank. Maybe overkill, but I'd rather only do it once.

I looked at the soldering gun again. It's a Craftsman, and 250w, not 360w. At least 40 years old, and maybe 50. I looked online and ended up ordering a new gun that is very highly rated, has two heat ranges, and NO "duty cycle". This sounds like just what I want. I think peak is 250w, and low gear is 140w.

Thinking about that 80w "stick", I think it would be better with a radius on the chisel edge and ends. I'll give that a try, too. I wonder if this one has a "duty cycle" also, tho I don't see how that could be done within the confines of the stick design.

I've always used rosin core (electronic) solder, with NoKorode paste flux. All the solder I can find is no-lead type, and I'm worried. My stock is running low (also the flux) and both are about 50 years old. What's out there now that works?   Steve

[Dave Hull]

Steve,
I suspect that most tank soldering requires fewer Watts than it would at first appear. I think the higher ratings used in the "gun" designs are just to allow the rapid heat-up from cold. The heat flow out of a joint on a hobby project would seem negligible. (Who uses a 6 oz. copper anything on a "cry over every ounce" model airplane?)

I found I prefer a pencil-type iron to the gun for better dexterity and lighter weight. The one I bought was a Weller 80W marketed for stained glass craft soldering. It came with a large tip and a medium tip. The only thing wrong with it is that it gets too hot, and is not adjustable. So I "adjust" the temp by unplugging between seams. The tip retains heat very well. It hasn't been enough of a hassle to warrant replacement so far...but it is on the "to do" list. But that inconvenience was never enough to tempt me to get the gun out of the drawer....

I would second the observation made earlier in this thread--that the oxidation of the tips and holder due to the temperature can catch up with you. Another issue may be that using acid flux with silver solder reduces the life of the plated tips. Once the plating is degraded, it seems that the solder doesn't wet out well on the tip.

The hardest tank I have worked on yet was a simple geometry, large-sized stunt tank--but I tried making it out of material from a gallon lacquer thinner can. I just couldn't get it clean enough to easily solder. It did solder, and eventually made good joints, but was about three times the work. I tried it because the K&S tinned steel sheets available in the hobby shop weren't big enough to make the main body in one piece, so I would have needed an extra seam. End result showed that was a bad decision!

Dave Hull

[Scott B. Riese]

MY 2 Cents......

100110011100011110 delete
Still......good job!!

[Garf]

The main problem today is the flux. The "environmentally friendly" flux simply doesn't work. I got some commercial flux from work, and got some flux from China (Ebay) that still works pretty good, but the domestic stuff is useless.