Phillips Speedtwin ST2 Scratch Build Blog.

Papa · January 01, 2013, 05:22:06 PM

The nacelles are built over formers using 1/16" x 1/4" strips. It should be no problem just tedious. Because the stock is so thin I will have to be careful so as to minimize sanding. I'm going to use medium to hard stock. Covering will be more of an issue.

I have made some progress over the holidays. I installed the Golden Rods for the rudder and elevator.

I also finished the cockpit/battery hatch. I don't think the pilots are the correct size just a bit too large. Need 1:7 scale pilots.

The blue camouflage will be a challenge so I did some trial stuff on the stabilizer. I'm pleased with the look but I'm using three different manufacturer's film and all have different sealing temperatures. I have to watch the heat on my irons carefully.

I bit the bullet and started to experiment with my vacuum table. The plug I made was Blue Foam finished in plaster. The set up was a shop vac with a 5H.P. motor and some fairly thick PVC. In the interest of marital peace I used the 4 slice toaster for heat. My table is 12" square so I had to cut the plug along a natural joint on the prototype to make it fit.

The lessons are the table works fine a draws a tremendous amount of vacuum. The plug needs to be made of wood so it's back to square one on that front. finally the toaster will only work with small plugs and thin PVC. I could not get even heat all through the film so it's back to the oven for the next attempt..

Papa · January 01, 2013, 05:36:50 PM

Hi Rob, here are some pictures that the designer posted when he was building the original model. Any comments or pitfalls?

Jack.

piker · January 02, 2013, 10:30:28 AM

Hey Jack! You'll have time to build a few more planes before the Spring at the rate you're going!

Nice work on the covering trial.

Those construction photos of the nacelles look very nice. I don't see anything wrong with the technique.

Andy Hoffer · January 02, 2013, 05:32:11 PM

Quote from: Papa on January 01, 2013, 05:22:06 PM
The nacelles are built over formers using 1/16" x 1/4" strips. It should be no problem just tedious. Because the stock is so thin I will have to be careful so as to minimize sanding. I'm going to use medium to hard stock. Covering will be more of an issue.

I have made some progress over the holidays. I installed the Golden Rods for the rudder and elevator.

I also finished the cockpit/battery hatch. I don't think the pilots are the correct size just a bit too large. Need 1:7 scale pilots.

The blue camouflage will be a challenge so I did some trial stuff on the stabilizer. I'm pleased with the look but I'm using three different manufacturer's film and all have different sealing temperatures. I have to watch the heat on my irons carefully.

I bit the bullet and started to experiment with my vacuum table. The plug I made was Blue Foam finished in plaster. The set up was a shop vac with a 5H.P. motor and some fairly thick PVC. In the interest of marital peace I used the 4 slice toaster for heat. My table is 12" square so I had to cut the plug along a natural joint on the prototype to make it fit.

The lessons are the table works fine a draws a tremendous amount of vacuum. The plug needs to be made of wood so it's back to square one on that front. finally the toaster will only work with small plugs and thin PVC. I could not get even heat all through the film so it's back to the oven for the next attempt..

5.0 HP Shop Vac ?!! Yikes. That's 3700 watts! Is that a 240-volt machine? You could vacuum boulders with that much power.

Andy

Papa · January 02, 2013, 06:17:23 PM

Just about, I can't pull the frame off the table unless I switch off. Even the dimples show up. Vacuum is not a problem.

jack.

Papa · January 15, 2013, 10:17:20 AM

I had to go almost to the bottom of the page to find my blog. How active is this tread. Have been doing some work on the model but did not take any pictures. So here's a collection of progress to date.

I covered the upper surface of the wing and built in 3mm of washout.
I have started the strips for the nacelles, that's very tedious work.
I remade a plug for the canopy. The bottom is obechi and the top is hard balsa.
I need to fill in with some body filler to finish it off. Then I'll vacuum in two parts.
I bought two matched spinners from Maxx Products International (MPI). One
standard rotation and one reverse rotation. I also picked up props at Pinnacle.
I love contra rotating twins and had planned on this from the beginning as it
eliminates the need for right trust. Electric motors are so versatile.

Back to the tedium. Beats going out and risking the 'flu bug.

Jack.

Michael · January 15, 2013, 10:59:33 AM

Nice work and nice spinners.

I'm really impressed with the clean working table.

piker · January 15, 2013, 12:05:24 PM

Awesome, Jack!

Just take your time with the sheeting and try to do a nice job (as I'm sure you will). Your efforts will pay off. Also try to keep the clue away from the top surface or you'll never get the form smooth (talking from experience

)

BTW, I noticed your thread was getting pretty low on the page the other day when I bumped a couple threads, but I knew you'd be updating soon, so I left it there

I should update my SE5a progress report too.

Papa · January 25, 2013, 10:16:25 PM

Managed to get some progress. The nacelles will be finished tomorrow. I finished the plug for the canopy vacuum and will be pulling a draw shortly.
I also started the cowls. The original was built up from scraps but I'm doing them from solid blocks of medium balsa. I will be carving out the inside once its finished on the outside. They are handed so I have to be careful to keep them separated. They are rough cut for now and I will finalize the shape once the nacelles are sanded. Sorry Ed didn't have a beer can.

Jack.

Ededge2002 · January 25, 2013, 10:34:19 PM

I guess the can of beans is a suitable substitute lol. They do both cause gas!

Wingnutz · March 13, 2013, 08:26:18 PM

Jack,
You're a brave, confident builder sharing a plans build like this. What I've seen looks great and I'm impressed.
Your experiences with thermo vaccuum forming sound familiar.
Dad and I have been working on a plans built Cessna Bobcat about the same size as your twin for nearly three years and although I've learned a lot from the building, my part of the model is not good enough for public scrutiny. Our plans show a model for IC power, so electrification is the present challenge
I'm hoping you have already solved or largely solved this and will once again share some secrets.
1. Where will your ESCs be located?
2. How will you access the battery?
Pictures are really worth a lot of words so if there are any recent photos of your build, we'd love to see them.

Papa · March 14, 2013, 10:53:36 PM

Hi Bill, still working on it but it has slowed down somewhat as I'm doing the nacelles and it is decidedly fiddly. I have almost finished the second nacelle, about 1 hour away from filling and sanding and then progress should speed up.

To answer your questions I have decided to mount the ESC's on the centre of the wing on the upper surface. Just double sided tape to hold them in place. I looked at putting them near the motors but it was a tight fit and if anything went wrong it would mean cutting the wing to get at them.
The battery access is in the fuselage under a very big hatch so access will be simple.

Jack.

Wingnutz · March 15, 2013, 07:42:00 AM

Hi Jack,
I've put my ESCs on the bottom of the centre section of the wing. The nacelles stick down far enough below the wing to protect the ESCs. I'm planning to build the hatch in the windshield area. Where did your hatch end up?

Papa · March 15, 2013, 09:55:21 AM

The hatch is actually the cockpit so it goes on top of the fuselage for about 8" x 4" so lots of space.

Jack.

piker · March 15, 2013, 10:44:28 AM

What's going on here? Is Bill building the same plane?

Good to hear some activity on the Speedtwin again.