Just a quick test… With my brand new iPhone 4S. The camera on this thing is awesome. I should be able to post better pictures… More often!

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Working with 14 pages of rolled plans, a beautifully written and photographed construction manual, and a box full of extremely precisely laser cut parts, the Hangtimes (Aviation Concepts) Schweizer 2-33 is coming together nicely. I’ve got the fuselage framed up as far as I can go withou the wings, the horizontal and vertical stabilizers, rudder and elevator are framed, and it is looking like a 2-33 !

Out of the shop for the first time, the 2-33 fuselage is nearly complete

This is one of the best instruction manuals we've ever encountered in an RC kit

Here's a tighter view of the forward fuselage. Note the steel strut attach fittings.

The 2-33 stabilizer is framed from 1/4 inch balsa

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There's a ton of beautifully laser cut parts in the 2-33 kit

When I got home with my treasure, I realized that the fiberglass cowl, the vacuum formed canopy and top window glass… and the instruction manual were all missing.  A quick e-mail to Gunny in New York… and the missing components were on their way.  I was just plain BLOWN AWAY when the instruction manual arrived.  I’ve been building models for almost a half century, but in that time I have NEVER seen such a well written, beautifully illustrated (with color photos and supplementary drawings) manual as this one.  It all is assembled into a three-ring binder, and the pages are printed on very heavy, gloss stock.  The manual is truly a work of art… which is only fitting, as it needs to match the kit, which is also extremely well done.

Here's the stack of plywood bulkheads for the 2-33

Here's a few of the formers, glued in place (with a laser cut template to get the angle right)

The fin and rudder go together pretty quickly.

Meanwhile, check out the kit at Gunny’s “Hangtimes” website at www.hangtimes.com/schweizer.html

There’s also an excellent build thread on the 2-33 at www.rcaerotowing.com

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I’ve been terrible about putting up blog posts on a regular basis, and I’m going to try to be better about it. but for now, I’m back to trying to remember how to interface with the website blog through my iPad. Hopefully, you’re successfully reading this… And learning that I successfully ran the brand new DA 120 engine on my shiny new Hangar 9 33 percent Pawnee towplane. good Lord, what a Beast that engine is! I got a pretty good upper body workout just holding it down, so the whole plane and steel saw horses support didn’t pitch forward and crash into the driveway!

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I’m back from the workshop…. with some pretty cool progress on making fuselage and wing molds.  I’ve known for some time that Stefano Duranti’s DevFusCad and Profili Pro applications not only can design (and cut with CNC) conventional, built-up structures, but can cut molds with a CNC router as well.  But I also knew that there was an intermediate CAM software requirement… to take the STL (Stereo Lithography) files that the DevFus and Profili programs generate, and convert them into usable G-Code that my CNC router could read.

What finally pushed me over the edge into this great new technology was when I read that Vectric’s Cut3D program would do the conversion.  I am a BIG fan of the Vectric Cut2D package, which by it’s name, obviously is intended for two dimensional cutting. I’ve been using Cut2D since I first completed my CNC router.  The interface is extremely user friendly, and the results have been nothing short of amazing.  So… it wasn’t much of a leap to move up to Cut3D.  I downloaded the free demo version (at www.vectric.com).  They provide a variety of sample files that you can play with to your heart’s content… and actually cut the finished pieces with your CNC router.  They have a sample file of a leaf shaped candy dish (they call it a “bowl”… Those Brits !).  I loaded the sample file into Cut3D, and found that the interface was very similar to Cut2D.  Just read what’s on the screen, and make decisions based on the configuration of your CNC machine, and the size of the part you want to cut.  There are seven numbered tabs that you can click through (or go back and forth), until you get the result you are looking for.  The 3D display of the part can be rotated in space, enlarged and reduced…. and the final cutting paths for roughing and finishing cuts are previewed in an animated movie that can be viewed from any angle.

Bottom line…. in about an hour, I had a finished, leaf shaped candy dish in my hand.  A few minutes later, I ordered the actual working version of Cut3D…. and an hour after that, I had a sample wing section drawn and ready to cut.  I’ll be going into a lot more detail about this here soon… but in the meantime, if you have a curiosity about CNC cutting, check out our sister website at www.abcsofcnc.com.  YOU can build your own CNC router, milling machine, laser cutter, etc. and it will open up a whole new world of precision and production speed that you’ve only dreamed about.  We’ve got a two hour video available at that website that takes you through everything you need to know to get started with CNC in your home workshop.

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I just discovered that my air ambulance pilot friend Curtis Suter published a complete set of Excel spreadsheets….. that are great for calculating the correct C.G. position for your sailplane, the wing area, Mean Aerodynamic Chord (MAC), and a whole lot more.  I’m going to be putting together a tutorial on how to use this great resource, but in the meantime, I just wanted to get the link out there, and let you start experimenting with it.  There are actually three separate spreadsheets (you’ll need Microsoft Excel, Apple’s Numbers, or one of the other spreadsheet applications that are out there).  The primary sheet is for cruciform (conventional) tailed sailplanes, and there is an add-on conversion sheet for dealing with Vee tails, and also a flying wing design sheet.  All three are available (plus a bunch more great utilities and tools) at http://www.tailwindgliders.com/Files.html#Files

Here’s a screen shot of a few of the pages of the spreadsheet, just to give you an idea of what is available.  These are GREAT for analyzing an existing design, creating a new design, or just checking the C.G., and set-up of your current bird.  And the graphics built into each sheet automatically change as you change the numbers, confirming that you are working with accurate numbers.

Just fill in the blanks in the yellow blocks, and the sheet will do the rest...

Again.. fill in the blanks, and determine optimum dihedral

This sheet will help set the C.G. for best performance

Download the complete set of spreadsheets, and set up your sailplanes “by the numbers”.  These sheets take all the work out of the process and will help you get the optimum performance from your soaring birds.

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The Fourth of July weekend is just winding down. The big city sponsored fireworks show will be starting in just a few minutes. I’m moderately sunburned, and fairly tired… But it has been a great weekend. Our Albuquerque Soaring Association group got fairly well “skunked” as far as our traditional slope soaring trip to Green’s Peak goes. The “Wallow” fire in Eastern Arizona caused the Sitgreaves Natioanl Forest to be shut down, so there was no possibility of slope soaring at Green’s Peak.

So we had to find an alternative for RC soaring. The group decided to do a camp out/ pot luck dinner / fun fly at our usual sod farm flying site. The friendly management at Gardner Turf Farms agreed to alow us to park our various travel trailers, motor homes and awnings at the side of a sod circle for the three day weekend, and the non-stop fun began.

I’ve been campaigning for a long time to get some aerotowing activity started within the club, and we’ve done a bit of it in fits and starts. But this weekend, the stars aligned.. and we flew and flew and flew. I was the designated tow pilot on Saturday, and I think I pulled up about 25 sailplanes. (Not all different ones… Some pilots got as many as four flights on a sailplane). Scale sailplane nut and all around nice guy Bill McLean provided his Hangar 9 Super Cub, powered by a DA 50 cc engine. Once we tracked down a bad electrical connection to the ignition, the DA … and the Cub performed flawlessly.

With a fairly steady 10 mph breeze, we determined that a “three leg” flight pattern would get the sailplanes up to about 800 feet. A straight take-off into the wind, followed by a gentle, 180 degree left turn (away from the pilots) followed by a gentle 180 degree right turn (again away from the pilots) and a straight leg into the wind …and the sailplanes were high enough to be somewhat difficult to see.

As with full size practice, as the gliders released, the tow plane would break left and down, and the glider would break right and up. I’d push the Cub downward at a reasonably rapid rate, set up a three leg downwind, base and final approach .. And land with enough speed to not mush or stall into the 10 knot headwind.

Usually, there would be another sailplane waiting to take off. The launch dolly that Buzz, the plumber, built from PVC pipe, and wheels scrounged from a toy truck worked very well. I’ll have details on building a dolly like that one here very soon.

Bottom line ? Aerotowing is a blast .. and I am working “Full steam ahead” to get my own tow plane built! You’ll see it here first !

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Pardon this departure from my regularly scheduled programming. This entry is being written from my shiny new iPad.. Which has to be one of the sneakiest, most insidious devices ever invented. Did I mention that I love the darned thing. Anyway, if you’re reading this, it means that I got the WordPress app for the iPad figured out.. Which means that there will be more to read here at SoaringStuff, Stay tuned!

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Here in Albuquerque, we had a very unusual circumstance….. a local modeler, who had a VERY LARGE collection of unbuilt scale, RC Sailplane kits, had some severe medical issues, and had to part with his collection.  He donated them to the local club… the club had an online auction…. and suddenly, everyone in this very active RC soaring community has two, three, four, or more scale sailplanes.  Great!…. Except for one detail…. we seem to have a real shortage of viable tow planes.  I could go through a sad, tearful account of some stuff that contributed further to our tow plane shortage, but I won’t.  I’ll just say that I am working feverishly to come up with a quick (but not too dirty) solution.. to add at least one viable tow plane back into the inventory.

We decided to forego some of the romance of a scale towplane, and just put together something that is big, strong, tough, and most important… quick to get into the air. A search on the internet came up with some possibilities that are offered in kit form that are nice aircraft, but a bit spendy.  But I did find a website that offers FREE (Hey… anybody can afford FREE!), downloadable plans for a couple of slab sided tow planes in two sizes.  Enter the Greenley!  The somewhat silly name comes from the designer’s name, John Green.  He offers an 80 inch version with a foam wing, a 100 inch version with a two piece, built-up wing, and even an electric powered version called….. (drum roll please!)… the Ampley.  You can go here to see all three versions of the plane… and the free downloadable plans in both DXF and PDF formats.

John Green Poses with his Super Greenley... Free Plans Available!

John’s design uses a perfectly symmetrical airfoil, and strip ailerons.  Like most modelers, I always feel the urge to modify things a bit, so I’m leaning towards a proven, thick semi-symmetrical airfoil like the NACA 2415… and barn door ailerons and flaps.  Since I’ve got a CNC router in the shop (if you don’t already know about such things, check out our sister website at http://www.abcsofcnc.com and learn how you can have your own CNC router) I plan to cut the parts for the new tug out of 1/8″ birch aircraft plywood, and 1/8″ Luan Mahoghany door skins.  Luan is a very inexpensive material that is light weight, fairly strong.. and did I mention INEXPENSIVE!  It’s getting harder to find, but we’ve got a local lumber yard that stocks the stuff in 4 x 8 foot sheets.  It will make great fuselage sides, and the birch ply will work well for wing ribs, etc.

Using my favorite suite of RC model design software (Profili Pro, DevCadCamPro, etc… all from www.profili2.com) I’ve got the two 60 inch wing panels drawn up… with 4 inch rib spacing, 18 inch chord, and 1/32″ ply leading edge sheeting, it’s starting to look like a wing.I ordered two 42 inch, 1 1/2 inch diameter aluminum wing tubes from Tom Kroggel at www.tntlandinggear.com and I’ve got a scheme cooked up to join the tubes (Non-Permanently) at the center section.  Obviously, there’s a lot more to come, but the wheels are definitely turning, and hopefully, I’ll have this big bird flying in a month or less!

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Based on our previously established definition that sailplanes are able to climb from the altitude where they are released, and gliders can only fly down in “sled ride” style, we boldly venture forth into the ever descending world of …. Gliders!

It was amazing to see how many gliders are permanently enshrined at the U.S. Air Force Museum in Dayton, Ohio.  Starting with the classic Geman SG-38 “Schulgleiter” (Yes… that translates into “School Glider”.)  After World War I, the Germans were prohibited by International Law from developing powered aircraft. But they were allowed to design and build gliders (and sailplanes), and they were very prolific in that effort.

Many Luftwaffe pilots first took to the air in an SG-38 like this one, with barely even a kitchen chair for a seat.

The Schulgleiter was the first exposure to aviation for many potential Luftwaffe pilots.  The tiny little “kitchen chair” gliders were launched off a hill top with a bungee, and the instructors yelled at their students through megaphones. Once the pilots could successfully fly down the hill without crashing, they were allowed to move on to more advanced aircraft.

In the United States, aspiring Air Cadets flew in the TG-3 (manufactured by Schweitzer, in Elmira, New York) and the TG-4 (manufactured by Laister-Kauffman).  The TG-3 was the precursor of the popular and famous 1-23, 1-26, etc.

American airman dodged the tiny SG type primary gliders, in favor of more advance training gliders like this TG-4.

These early training gliders were launched with a bungee cord... secured at each end and stretched.

Probably the most famous American gliders in World War II were the CG-4 troop gliders, known at the “Hadrian”.  These lumbering boxes had a pilot and co-pilot, and carried 13 troops and their equipment.  There were over 14,00 of the CG-4′s built… by companies including aircraft manufacturer Waco (in Troy,Ohio), and by the Gibson Refrigerator Company!

We spotted a great model of the CG-4 troop glider, and it’s C-47 tow plane at the Joe Nall Fly-in this past May. (If anyone knows the name of the builder, we’d love to share it here…)  These models are a great representation of a heroic part of American history.  The stories of near or realized disasters are everywhere.  The Germans soon figured out that the CG-4 gliders had to have an open landing area, so they would “booby trap” any likely landing spots with welded steel structures designed to shred the fragile wooden fuselages on contact.  And, of course, the slow flying, cumbersome gliders and C-47 towplanes were easy pickings for German anti-aircraft guns.  There’s an equally large number of stories about the CG-4 pilots flying along in formation, and suddenly seeing a jeep, or a howitzer cannon falling out of the air right in front of them…. the victim of another CG-4 that was blown out of the air above them.

These were a somewhat less than successful effort in the invasion of Europe in World War II

Look Ma! No Engines!

I learned a lot about our glider history at the Wright-Patterson museum, but clearly the most incredible is the story of the Chase XG-20.  What… you don’t recognize that name?  O.K… .How about the Fairchild C-123 Provider ?  Do you remember the movie “Con Air” that starred Nicholas Cage.  In the movie, Cage’s character was flying home, to be released on parole from Federal prison, when fellow prisoners stage a riot on the plane.  That plane was a C-123.

Nicholas Cage, and the C-123 Starred in "Con Air"

O.K…. so what does all of this have to do with gliders?  Well, it turns out that the original 30,000 pound, all aluminum aircraft… with stubby retractible landing gear (and an on-board Auxilliary Power Unit to drive the hydraulic landing gear) was built AS A TROOP GLIDER!  I’ve done a fair bit of research on this bizarre aircraft, and learned that it was developed by an obscure Chase Aircraft Company, to get a contract that the U.S. Air Force initiated in 1953.  They built one prototype (which never flew… probably because they couldn’t find anything that would tow it into the air ?)

In short time, Fairchild Aircraft took over the design, hung Wright 2800 engines on the leading edge of the wing (and grafted fuel tanks on, immediately behind the engines) and Voila!… the C-123 Provider.  Several hundred of these birds were built, and they flew very successfully, all the way into the Viet Nam era.

Just think about it…. 120 foot wing span.  76 feet long.  Flight crew of four…. nearly 30 feet tall.  And they thought they would tow this thing into the air!  It begs the classic question… What Were They Thinking ?

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