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Jul 13, 2011, 03:27 PM
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Build Log

40% Schueler-Fleckstein AS-W 15B

Welcome to the build log of my 40% AS-W 15B. First some background. This is a Schueler-Fleckstein kit produced in the late 90's. Back then I was corresponding with Robin Lehman about acquiring a scale glider, and Robin mentioned that he was expecting a 40% scale AS-W 15B soon from SF with an anticipated list price of $2500.00. I told him I was interested, but honestly that was a bit beyond my means back then. I was a lowly entry level engineer making peanuts at Scaled Composites and paying off student loans etc. About a year later the glider finally was for sale, but at $3500.00! I wonder if I could have locked in the original price? Probably not. Anyway, that was more than a months pay for me back then and I didn't buy it. But I was kicking myself ever since.

The AS-W 15B is my absolute favorite sailplane. The lines are perfect. I like the lower aspect ratio and the cross tail and the dolphin fuselage. So over the years I obsessed over a large scale AS-W 15, occasionally searching the web for one for sale. Well, lo and behold a few months ago I came across an ad on the RCAerotowing site for the very glider that I had been searching for. I wasn't going to lose this one! I had a cashiers check in the mail the next day!

I got some really interesting info on the background of this glider from Asher Carmichael that I would like to reprint here:

That is one gorgeous plane and it looks very familiar. I believe it's the same plane I sold to Wil in about 2003. Some planes in our hobby seem to maintain a history so in an effort to maintain one for this airplane, here's some pertinent info which you may or may not care about.
This is one of two 40% Fleckstein 15's in the US. My OFB, Rusty Rood and I brought them into the US in 2000 via Robin Lehman. Rusty built his and I let mine sit until Wil wrestled it away in 2003. Rusty's is a work of art and he flew it for several years until he sold it to Mike Lance, in SoCal, in about 2008. Mike doesn't frequent the forum but you may be able to contact him through some of the SoCal group such as K2K, S2000, PT glider, Alvaro Corzo, etc.
Rusty complained early on about the airplane "feeling heavy" in the thermal but thoroughly enjoyed flying it. Word is Mike adjusted the CG and it turned into a completely different, read wonderful, ship. You'll need to talk to Mike to get his input if at all possible.
As for building, someone with your background should have no problems, but ask away as there is plenty of help available here on the forum.
BTW, Fleckstein was in partnership with Reinhard Schueler in the 90's in Germany. Schueler and Fleckstein were known for their "hardshell" composite techniques which was highly prized for the surface durability and stiffness. The most popular plane in the US they produced is the venerable ASH-26 in 1/3 scale. There are probably about 20 of these still flying in various parts of the country. They are highly sought after. Your 15 will be likewise.
I believe Schueler still carries on the tradition but rumor has it Fleckstein retired with back problems shortly after producing a limited run of the 15"s.
Now, on to the build! Keep us posted.

I contacted Rusty later and he was really helpful. Rusty even mailed me a stack of scale documentation photos that he took of a full sized AS-15B. I'll try to scan the photos and post them here.

I hope you enjoy my build log.


Last edited by aeroanalysis; Jul 13, 2011 at 07:37 PM.
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Jul 13, 2011, 03:39 PM
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First, I had to get the glider from Wil Byers in Washington St to me in N VA. I posted most of this in another thread, but for completeness I'll add it here as well.

I used and got dozens of quotes within seconds of submitting my RFQ. I had entered a shipping class (300) from an online calculator based on the dimensions and weight of the crate provided by Wil. If you leave this blank, the shipper can change the class on you and charge you more than they originally quoted.

I picked the lowest quote, which was from Estes, which is a well known shipper. All of the shippers have good and bad feedback, so I figured I was risking something no matter which company I picked.

The cost to ship the 10 foot, 67 lb crate across the U.S. was $196.00. I thought that was a steal. I was shipping from a business address to a business address, which greatly reduces the shipping cost. I also said there was a loading dock at each end, even though there wasn't, but a 67 lb crate is really easy to get on and off a truck so I didn't think they would have an issue with that and they didn't.

The crate was fairly sturdy, mostly 1x2's and 1/4" plywood, but it got pretty beat up in shipping. I was worried about the several holes and cracks in the crate, but after unpacking the glider seemed to have survived. There was a hole at one end of the crate that could only have been made by a forklift fork, and the crate would have had to have been up on one end based on the orientation of the hole. Yikes! The glider was packed really well, which helped it survive the ordeal.

The crate was insured for something like $25.00/pound, which doesn't even come close to the value of the glider. There are insurance providers that will supplement the shippers insurance for a fee, but I didn't add the additional insurance because I'm cheap and it was delaying the shipping.
Last edited by aeroanalysis; Jul 14, 2011 at 07:24 AM.
Jul 13, 2011, 03:51 PM
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I was putting off ordering servos, but then I realized I wasn't going to get very far without them so I ordered servos. Total of 8 servos, all Hitec. Here's the list:

Rudder: HS7990TH
Elevator: HS7990TH
Ailerons: HS7955TG
Spoilers: HS7955TG
Retract: HS7950TH
Tow release: HS7950TH

The HS7990TH is new servo from Hitec. From the Hitec website:

"Hitec's most technologically advanced servo, the "Monster Torque" HS-M7990TH features an ultra precise high resolution magnetic encoder instead of a conventional mechanical potentiometer. Designed to operate on a two cell LiPo Pack the HS-M7990TH features our newest high resolution "G2.5" 12 bit generation programmable digital circuit and our indestructible Titanium gears. Other features of the HS-M7990TH include a 7.4V optimized coreless motor, integrated heat sink case, and a top case with two hardened steel gear pins supported by brass axial bushings."

It's 10% larger than the standard Hitec servo case, which isn't a problem.
Last edited by aeroanalysis; Jul 14, 2011 at 07:29 AM.
Jul 13, 2011, 03:59 PM
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The first thing I did was clean off ten years of old masking tape using GooGone. This stuff works as advertised. I used paper towels and lots of scrubbing, followed by a thorough cleaning with IPA. It was pretty hot and humid in the shop and it took a couple of hours, but otherwise no problem.
Jul 13, 2011, 04:27 PM
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Next I tackled the retract. The first thing was to get the wheel installed. The wheel hub has a 12mm hole for the axle, and the axle was 8mm in diameter. Hmmm. McmasterCarr to the rescue! Next day the 12mm OD 8mm ID flanged bronze bushings arrived. Apparently the hole in the wheel wasn't quite 12mm, but with a little persuasion from the drill and the arbor press, we were in like Flynn.

Next I needed a spacer to keep the wheel centered on the axle. McmasterCarr to the rescue! Next day two bronze bushings showed up courtest of FedEx. The bushings were too tall so I introduced them to Mr Mill.
Jul 13, 2011, 04:41 PM
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Now a new issue cropped up. The axle retaining bolts weren't quite flush with the retract fork and the bolt heads were snagging on the gear doors during the retract cycle. Of course metric fasteners use a 90 degree countersink which we didn't have in the shop so a set of cheap 90 degree countersinks were ordered from Grizzly and a they showed up a few days later. If only everyone shipped as fast and cheap as Amazon and Mcmaster.
Jul 13, 2011, 04:49 PM
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Looking great Aero!, keep up the good work and the pictures!
Jul 13, 2011, 05:01 PM
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Next order of business was to mount the retract servo. The geometry was a little weird and I decided to machine an aluminum mount to get the offset needed to get things lined up. I found a little billet of rectangular stock that we had lying around the shop and designed the retract servo mount to work within the dimensions of the piece. Just like Michelangelo, I removed everything from the aluminum billet that didn't look like a retract servo mount.

Machining was a bit tricky because we don't have a DRO on our mill and I had to make a lot of pencil notes on the drawing as I went along to keep from losing my place and having everything go to hell. Normally we would just pay $40-$50 to an outside shop to machine this part on an NC mill, but I wanted to do it myself. Besides, it only took a half hour.
Jul 13, 2011, 05:16 PM
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Installing the retract servo mount is next. I had avoided disassembling the retract up until now, but I had to countersink the holes for the retract servo mount bolts to clear the retract fork, and the bolts install from the inside and the drill doesn't fit between the fork blades. I took lots of pictures to make sure I could put it back together the way I found it and that foresight definitely paid off! I needed some 5mm flathead fasteners to mount the retract servo mount, efficiently provided by my buddies at McMaster. The 90 degree countersink was brought out of the tool cabinet and given another whirl.

In hindsight, I don't know why I chose to mount the retract servo mount with metric fasteners. Everything on the glider up to this point is metric, but all of the control hardware is going to be non metric. Oh well.
Jul 13, 2011, 05:48 PM
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Next thing I needed was an actuator arm for the retract. The glider came with a brass collar with a spring pin to keep it from rotating on the shaft and an M3 bolt as the actuator. I wanted to make this work because the alternative seemed daunting, but in the end I decided that the bolt was too Mickey Mouse for this size glider. I replaced the bolt with a machined brass arm soldered to the collar. This turned out to be an relatively easy job, but I had to learn how to solder brass. Not too hard, it turns out.
Last edited by aeroanalysis; Jul 14, 2011 at 07:35 AM.
Jul 13, 2011, 05:58 PM
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I used 6-32 threaded rod for the linkage rod. The ball links are Dubro 4-40 Monster Ball links. These are not the super heavy duty links, but the Monster links. I am adverse to plastic hardware on a glider this size, but these links are the bees knees. Note that the 6-32 links are the exact same link, but with a ball drilled out for a #6 fastener and the interior hole for the threaded rod larger in diameter, but it's not a bigger link. I use the 4-40 links and drill and tap them for the #6 threaded rod so I can use #4 fasteners at the arms. #6 fasteners puts too big of a hole in the servo arm and is overkill. I should mention that I'm using Nylocks everywhere.
Last edited by aeroanalysis; Jul 13, 2011 at 07:40 PM.
Jul 13, 2011, 06:31 PM
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Subscribed, cool airplane.
Jul 13, 2011, 07:10 PM
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Originally Posted by NighthawkF-117
Subscribed, cool airplane.
Second that and serious building skills on Aero's part!
Jul 13, 2011, 07:35 PM
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The retract mechanism has a mechanical gain that speeds things up quite a bit. I pulled out the old servo programmer wahoozit and entered a 30% transit speed. I still think it's a bit fast so I might slow it down later. The Hitec HPP21 servo programmer is inexpensive and super easy to use and I highly recommend it. I posted videos of the retract in operation over in the videos section:
Jul 13, 2011, 07:45 PM
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Next up is the retract door closing springs. It's going to take me a week or two to make enough progress to make a post. Be patient in the meantime.


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