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Old Mar 01, 2011, 10:16 AM
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Quote:
Originally Posted by Don Stackhouse View Post
Think "The Karate Kid". "Paint the fence..." "Sand the floor..." "Wax on, wax off..."
Okay, Mr. Miyagi.

But seriously guys, thanks for the instructions and tips. I'll try them out. Going slower and pressing lighter and not worrying about how fast I think it should go is probably as important as anything.

I've got some more photos from this weekend, just haven't had a chance to get them off the camera. I'll see if I can post them when I get home.
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Old Mar 01, 2011, 09:33 PM
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Not as much progress as I thought I had to report. I've got each wing panel nearly done, just need to cut off the excess spar bits and sand everything nicely. As you can see, I moved to a glass surface for putting on the sheeting and gluing in the diagonal braces. The glass is flatter than my building board, but I cannot pin into glass :-P

I've got some other obligations to take care of over the next few days, but I'll be back at it by the weekend.
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Old Mar 08, 2011, 10:51 AM
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I got back to it this weekend. After maybe a couple hours sanding the wing panels all over and especially paying attention to the ends where the panels will be joined together, I got to the epoxying. I used 15 minute epoxy to join the panels together since I never have enough time with the recommended 5 minute epoxy on anything but the smallest joints. Unfortunately, this meant I waited half a day for the outer joints to fully cure before moving on to the center joint, then waiting the rest of the day for that one.

That brings us up to Saturday night. I'll have Sunday's fun posted when I can.
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Old Mar 08, 2011, 05:42 PM
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I did steps 12 and 13 kind of backwards from instructions. I first glued the servos into place, then used that to figure the proper length for the Y cable. Instead of the "RTV Silicone Caulk" called for on the plans, I used a combination of servo mounting tape and Zap-a-dap-a-goo. The tape was nice because it held things in place while the glue dried. Zap-a-dap-a-goo is probably a bit more robust a glue than really needed, but it's what I had on hand.

I was able to cut down Y connector quite a bit since the servo leads reached all the way into the center section, and ended up chopping it up and re-soldering. I'm pretty happy with the results.
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Old Mar 08, 2011, 05:50 PM
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Now a question for Don or someone else who has built one of these in pure glider form before: The plans call for a 500mah battery pack. That's a 4xAAA size, right? That looked about right checking against the plans, but so do 4xAAs...
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Old Mar 08, 2011, 07:15 PM
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500 mah is the standard sized (or what used to be standard sized) nicad pack that was in the vast majority of radios, back before the indoor/backyard revolution. They're still pretty standard for regular-sized gas-engine sport models. It gives plenty of flight time, unless you're into slope soaring. The plane will of course carry a lot more.

It can certainly get away with less (I use a separate 270 mah NiMH radio battery in my electric, and get plenty of flight time from that). However, unless you do an extraordinary job of keeping weight out of the tail, going too much smaller in the sailplane version will just mean you're taking battery out and replacing it with lead to get the C/G correct. Might as well use battery, at least it's good for something more than dead weight.

Probably worth building the airplane without the battery, then (when everything else is settled, including covering/painting effects) see how much weight you need in the nose to put the C/G just a little (1/16") ahead of the aft C/G limit. Find a battery that weighs that much, or close to it, and that fits in the nose.

There are a number of different cell sizes that have about 500 mah capacity. If I recall correctly, one of those is referred to as "2/3 AA", about the same diameter as AA but shorter in length. There are also some 600 mah cells that are fatter than AA but short enough for their length to fit cross-ways in the nose. There are also some that are similar in size and proportions to AAA cells. In general the "square pack" type cell arrangements will fit best in the space available.
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Old Mar 09, 2011, 10:32 AM
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Thanks Don. Quite a reply as usual All the transmitters I've looked at buying only seem to have a flight pack of four flat AAs...hardly the thing to fit nicely in a glider fuse. Maybe I need to look higher-end at sailplane TXs to see the square and smaller flight packs (AAs were surely > 500 mah, even 10-20 years ago, no? I guess I should go look at mine).

I was hoping to pre-order the battery pack, but I guess I can be patient :-P I'm not yet used to the idea that weight can vary enough to need different sizes of battery packs. I did give myself a leg up in that regard, reserving the lightest basswood for the tail spar.
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Old Mar 09, 2011, 11:01 AM
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Quote:
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...All the transmitters I've looked at buying only seem to have a flight pack of four flat AAs...hardly the thing to fit nicely in a glider fuse.
Here's another chance to develop a new skill. It's not that hard to unwrap a flat pack and re-make it as a square pack. It may be possible to re-form it without resoldering, or at worst case you can unsolder a couple joints and resolder it into a square pack.

Quote:
Maybe I need to look higher-end at sailplane TXs to see the square and smaller flight packs (AAs were surely > 500 mah, even 10-20 years ago, no? I guess I should go look at mine).
Depends, but generally yes. The AA Eveready rechargables in my computer mouse right now are 2000 mah NiMH cells. However the 500 mah nicads that R/C flight packs traditionally used were a little smaller than AA cells.

Quote:
I was hoping to pre-order the battery pack, but I guess I can be patient :-P
Haste makes waste...

Quote:
I'm not yet used to the idea that weight can vary enough to need different sizes of battery packs. I did give myself a leg up in that regard, reserving the lightest basswood for the tail spar.
Or just get a 500 or 600 mah square flight pack and don't worry about it. You will be close enough, and the plane is deiberately designed to be not too sensitive to weight anyway.
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Old Mar 09, 2011, 12:52 PM
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www.cheapbatterypacks.com

Whatever configuration and weight you turn out to want to fit the nose of your model. I had a strangely shaped 1500 5 cell pack made to perfectly fit the (physical) size and weight requirements of my 3m full house ship.
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Old Mar 10, 2011, 07:25 PM
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I love that instruction sheet! They don't assume or leave anything to interpretation do they?
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Old Mar 10, 2011, 10:59 PM
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Quote:
Originally Posted by Don Stackhouse View Post
Here's another chance to develop a new skill. It's not that hard to unwrap a flat pack and re-make it as a square pack. It may be possible to re-form it without resoldering, or at worst case you can unsolder a couple joints and resolder it into a square pack.
I like this idea. Unfortunately, the only flat pack I have at the moment is from a 1991 Airtronics Vanguard system and will not be touched due to nostalgia. Bought it when I was 11 with garden watering money. (The lady across the street was too old to tend her garden so a few times a week I would go over, water the plants, then listen to some of her stories of the old times...good stuff.)

Quote:
Originally Posted by Don Stackhouse View Post
Haste makes waste...
I relearn this every once in a while--the hard way of course :-P I'm all too used to fast shipping from Amazon, instant movie watching with Netflix, news as it's happening, etc. Just have to tell myself to SLOW DOWN sometimes.

Quote:
Originally Posted by rdeis View Post
www.cheapbatterypacks.com

Whatever configuration and weight you turn out to want to fit the nose of your model. I had a strangely shaped 1500 5 cell pack made to perfectly fit the (physical) size and weight requirements of my 3m full house ship.
I was looking at them trying to figure out if a 500mah battery was what I thought it was. I'll get a pack from them when it's time.
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Old Mar 10, 2011, 11:34 PM
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I glassed the center wing panel joint. I mixed up one large batch of 30min EZ-Lam epoxy (15 min is spec'd), drizzled it over pre-cut glass tape and squeegeed it out as suggested. I think I went a little overboard with the squeegee because the glass looked wetted out but was so dry it hardly stuck to the balsa sheeting. This combined with my awkward press arrangement caused the bottom tapes to come out crooked with a couple puckers. Everything is adhered now, but I'm going to have to scrape off the puckers and re-tape to get enough strength on the bottom I think.

Last time I laid down glass tape, I laid dry fiberglass over balsa sheet, dribbled some epoxy on and squeegeed as I went. I'm sure it's heavier, but I had no worries about there being enough epoxy to stick glass to balsa, and it was easier to keep everything stuck down where i wanted it. It's tempting to do it that way for the remaining polyhedral joints, but I'll probably squeegee on separate wax paper again just not so thoroughly this time.

For my 'press' I used a buckwheat hull pillow on the bottom to conform to the dihedral angle and maintain even pressure, then placed the taped wing wrapped in wax paper over the pillow, then some smaller rice-filled bags over the wing and lots of weights on top to squeeze everything together. It worked pretty well, but I could have used a few more hands to keep from moving the bottom tape off-center as I laid the wing down. That or better technique...*cough*
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Old Mar 14, 2011, 06:34 PM
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Started on the fuselage

While I slowly glass the wing joints--which is going better now that I've got the hang of it--I decided to start on the fuselage.

The first step is to pin down and glue the 12" and 36" sections of bottom sheeting to the I trimmed the 12" piece, somewhat unnecessarily, so that I could better see the center line marks. I then drew the center line down the board and marked lines for the formers and tow hook plate, then glued those in place.

Next step was the lite ply side doublers and stringers. At this point, I decided to switch to CA to glue the doublers to the formers. Unfortunately, this caused me quite a bit of grief as the CA soaked into the ply until I squirted a whole bunch on there, so much that it wouldn't cure without help. I wished I'd just used wood glue, as I understand how to use it on joints like that. I did however successfully use CA to glue the ply sides to the bottom sheeting and to stick the stringers in place and finally (as suggested by Don) to glue the balsa sides on, though I was nearly overwhelmed by fumes.

I got the pushrod guide tubes tacked in place (CA + kicker) and coming out both sides for a V-tail. Drilling the holes was awkward since I decided I needed to keep the fuselage pinned to the board for some reason, but they came out well enough.

In the last step I laid down the top sheeting and hatch, waited for it to dry overnight then spent some quality time with my hand plain and sanding block enjoying the nice sunny weather we had Sunday. I glued down the nose block and ply bottom skid (wood glue, sorry Don :-P), using plenty of weights to hold things flat. This morning I added a patch of balsa to the slightly small nose block. Carving and sanding to a pleasingly round shape is next.

I must say that after all the work that went into the wing, it's nice to be making such fast progress on the fuselage.
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Old Mar 14, 2011, 10:23 PM
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I need to check with Joe about the nose block, just to make sure. However, I suspect you will find that your patch will pretty much disappear when you sand the nose to shape.
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Old Mar 14, 2011, 11:52 PM
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You can also check out radicalRC.com for the battery packs. I have purchased Rx packs and replacement Tx packs from them and have been very pleased. They give dimensions for the finished packs and weights. They have 720mAh and 800mAh AAA packs.

Wayne
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