Great Planes Super Stearman - build thread

[grosbeak]

I added more accelerated medium CA to other parts of the cowl ring when I got home and I got the cowl and ring off together the next day. I lost a batch of about 40 photos due to file corruption but here's an out-of-sequence picture showing the epoxied cowl ring.




After going to all that trouble with the mixture screw guide tubes, I wanted to able to access them with the cowl on. I like the idea of using a tripod-mounted laser to pinpoint the tubes and before and after sliding the cowl in place but I found it was too finicky; maybe I wasn't doing it right. After I while I went back to the tried and true tape-and-card stock method. I had a spare piece of 8-32 threaded rod; it was a little too loose for the tubes so I added some heat shrink... and a marking point.






I taped the card stock in place. Because the cowl is proud of the fuselage by 1/8" or so I brought it up to level with some folded paper. I marked each point in turn...




... then installed the cowl and transferred the marks.




To support the cowl while drilling I slid a roll of paper towel onto a piece of scrap clamped in the vise.




I selected the drill bit based on grommet size. When the holes were drilled I installed the grommets, epoxied them in place from the inside, and left the cowl to cure.

[grosbeak]

Time for some fun with the dummy engine. I set up my paint booth; the specific picture is among the photos lost but here's what it looks like.




Here's the dummy engine with the flat black painting done. Note the airflow cutout for the cylinder head of the real engine and the holes for the spark plug wires and rocker covers.




These pieces of 18 gauge wire will be the spark plug wires.




Spark plug wires and rocker covers in place.




Epoxy to secure the rocker covers and wire from the back.

[grosbeak]

The next step is to slide the dummy engine over the crankshaft of the real one, attach the cowl, position the dummy and secure it to the cowl with rubber bands. I didn't want the blocks to move at all so I tacked them together with PVA.




Here's the dummy engine in place with the cowl off.




The idea is to glue it in place with epoxy. Hysol would have been perfect for this because it doesn't run (or so I am told), but sawdust mixed with West Systems epoxy worked just as well. Not very appetizing though.








All cured. Does the shape remind you of anything? From Star Wars?




From the front...




... and on the plane.

[grosbeak]

On to the gas tank. I will be using a three line setup with a 330 mL Fiji water bottle as the tank. Here's the idea:




I started by moving the battery power and balance leads out of the way.




Here's roughly where the tank will sit.




I'll build a platform to strap the tank to, but first I wanted to reinforce the mounting location. I did so with some balsa glued in place cross-grain.






On to plumbing the tank. I start by piercing the centre of the cap.






That's followed with a 1/4" brad point bit for the hole. I twist it by hand, mostly backwards, for a cleaner bore.




Time to install the Aluminum Pick Up and Feed - with Double Barb.















I'm a big fan of PSP fittings - I get mine from http://www.thunderboltrc.com/.

[grosbeak]

On to the gas tank. I will be using a three line setup with a 330 mL Fiji water bottle as the tank. Here's the idea:




I started by moving the battery power and balance leads out of the way.




Here's roughly where the tank will sit.




I'll build a platform to strap the tank to, but first I wanted to reinforce the mounting location. I did so with some balsa glued in place cross-grain.






On to plumbing the tank. I start by piercing the centre of the cap.






That's followed with a 1/4" brad point bit for the hole. I twist it by hand, mostly backwards, for a cleaner bore.




Time to install the Aluminum Pick Up and Feed - with Double Barb.















I'm a big fan of PSP fittings - I get mine from http://www.thunderboltrc.com/.

[grosbeak]

Now for the fill and vent fittings. For those I use the Aluminum Vent - Single Barb.

It's keyed on the inside for 1/8" hex.




After drilling the hole in the bottle, it's just a matter of fishing the fitting and securing it.

[grosbeak]

On to the interior plumbing, which consists of a length of Viton tubing, two clips and a felt clunk.




Clunk on and secured.




Testing the cap fit.



Like wine bottles, Fiji bottles have a punt (or kick) in the bottom. The tubing needs to be just the right length so the clunk doesn't catch on it. After the first test I had to trim the tube a couple of millimetres.




The completed tank.




I'm still turning the location for the vent line exit over in my mind. The fuel dot will probably go on the starboard side. I really like the McFueler...



...and only just realized I forgot to order one for this build. I did so this afternoon, so that part of the plumbing will have to wait.

[Ramjet]

Cool build , nice job so far . I don't understand your reason for putting the vent on the bottom ?? I put both fill and vent top front( side by side). I guess your way would allow better draining of the tank ,is that it . I would worry about leaks, But then again I never drain my tanks ,I like to leave fuel in them so things don't dry up . anyway following with interest ,keep up the great work . cheer Roger

[grosbeak]

Cool build , nice job so far . I don't understand your reason for putting the vent on the bottom ?? I put both fill and vent top front( side by side). I guess your way would allow better draining of the tank ,is that it . I would worry about leaks, But then again I never drain my tanks ,I like to leave fuel in them so things don't dry up . anyway following with interest ,keep up the great work . cheer Roger

Hi Roger, I store my planes in the basement and do drain my tanks after flying, which is why fill (actually fill/drain) is at the bottom and vent is at the top. No problems with leaks... not yet, at least.

And thanks for the kind work... hope to get back into the build in the next couple of days.

[grosbeak]

While I'm waiting for the fuel dot I turned my attention to the vent line exit. I like to use a fitting instead of just letting a tube dangle, and my preference is the Sullivan Aluminum Nipple Fitting (SUL 476):



Where I wanted to put it, though, there was no way to thread the nut on afterwards. No problem, it's balsa. I'll drill an undersized hole and thread it in. How to thread it in, though? How about tapping some threads on the inside?



It worked great in a scrap piece... until it was time to remove it. I mulled it over for several days and finally decided to cut a slot for a flat blade screwdriver. I marked the scrap and gently cut the slot on the band saw.






In and out with no problem.




I've since hardened the threads with CA. When I install it I'll connect the vent line first, feed that through and spin it in concert with the fitting as I screw it in place. This should prevent twists in the line.