Floaters and Trainers

Easy Built Models Super Soarer R/C Conversion

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Type: 2 meter converted free flight model
Wingspan: 72"
Wing Area: ~347 sq in
Airfoil:Under cambered
Weight:27oz
Construction: Balsa fuselage, built up balsa wing and sheet balsa tail surfaces
Controls:Ailerons, rudder, elevator

This airplane has a long history of not being finished. Where to start...how about the beginning: The Super Soarer is intended to be a free flight "tow line" airplane (which presumably means it's supposed to be hand towed into the air like a kite). With it's gull wings and tear drop fuselage, it looks a bit like the Minimoa full scale glider of the 1930's (click here to see what the Super Soarer free flight is supposed to look like). This airplane was given to me by a friend, who had built the whole thing up, but not covered it. It had evidently sat around in his garage in it's nearly complete state for some time. At the time, I didn't even know what kind of plane it was.

Part 1:

I'm not sure if I got the idea before or after I saw the plane, but I suddenly thought it would be cool to aero-tow something with my friend's .40 sized Sig Fazer Fun Fly plane. To that end I decided to convert the Super Soarer to an R/C model, and add a rudder and elevator.

I was determined to get the plane going as quickly as possible. First step was to add some balsa cross beams to the wing to try and strengthen it up a bit...it seemed pretty flimsy. I also added some carbon fiber strips down the bottom of the spar and the trailing edge. Finally, I covered the wing in transparent blue Monokote, which looked really nice over the built-up structure. If nothing else, I figured, the plane would look nice hanging from my ceiling.

The fuselage was complete for the most part. It came with a little plastic landing wheel mounted under the wing, but it didn't seem suitable for an R/C plane. I replaced it with a light weight foam wheel I stole from one of my power planes (now that I think of it, this is the first glider I've ever had that has a wheel).

Gotta love those gull wings and the little wheel.

The next steps were more drastic: I had to add an elevator and rudder. Initially, I figured I would just cut the elevator out of the built up horizontal stab. I set about this task and quickly mangled the original stab beyond repair...argh! Oh well, it was easy enough to fashion a slab balsa stab.

Now the rudder. The vertical tail is a narrow elliptically shaped thing that sits atop of the horizontal stab. There is also a bit of a sub fin on the bottom of the fuselage. There was really no room on it for a rudder that would be an effective size. Rather then trying to enlarge the vertical (which would have made sense), I took the unorthodox route of creating a full flying vertical stabilizer. Actually, this same sort of thing is used on the C.R. Climmax HLG very effectively, so it seemed like a good solution. This involves putting a shaft vertically up through the rear of the fuselage. It then exits out the top of the horizontal stab. The shaft has a horn for a push rod to connect to it at it's bottom, and it pivots in a bearing, which gives the full flying fin it's ability to move. The part of the shaft that's exposed above the horizontal stab has a square brass rod on it, which slots into a slightly larger brass rod buried in the fin.

View of the full flying vertical stab.
The push rod and rudder horn can be seen below the horizontal stab.

Ah, push rods. I always hate installing push rods in gliders. Invariably, it is frustrating and messy, as gliders almost always have thin, long, inaccessible tail booms. On the other hand, the Super Soarer's tail boom is short, and fairly wide. Just one problem...ITS ALREADY BUILT! So, how do you go about installing push rods in a tail boom that is completely enclosed and has multiple bulkheads in it? Easy...take a metal wire and stab it through repeatedly until it comes out the other side! To my surprise, this "technique" actually worked. Of course, the inside of the tail boom now probably looks like it was attacked by an angry beaver.

The forward fuselage. It's quite a mess.

The final touch was the tow release for aero towing. Again, I opted for the quick and dirty approach...a cable push rod in a plastic housing that was exposed underneath the nose. The tow ring is attached to the exposed bit, and the end of the cable is then slotted into another piece of push rod housing further up in the nose. The idea is, when the glider is ready to be released, a servo pulls the cable out of the first bit of housing, allowing the tow ring to detach, and away you go!

The tow release cable.

I installed a couple micro servos for the rudder and elevator, a standard servo for the tow release, the receiver and battery, and the plane was ready to go...or so I thought.

Ready to go...or is it?

We arrived at the flying field, eagerly anticipating for the first flight. Yes, the first flight was to be an aero tow. Rather silly, but then the field was deserted, and I wasn't too worried about what could happen to the glider. My friend wasn't too worried about his power plane, the tug, either. Our first sign of trouble was when we test flew the Fazer tug with just the tow line attached. The rather unlikely tug seemed very sluggish lugging the 30 feet or so of monofilament around, and we wondered if it would really be able to pull the glider.

While my friend was sorting out the issues with the tug, I went over to the grass area of the field to do a few hand tosses to test the CG of the Soarer. First toss..everything looks good. Looks like I got the CG just right. Second toss...a bit harder...let's see how she turns. Right rudder...more right rudder...little more...more...full right rudder...IT WON'T TURN. The airplane does not turn! All right, maybe an even harder toss. Again, full rudder. The airplane just sort of skids to the right before nosing into the grass. Not good. I wasn't quite sure how the gull wing would affect the overall dihedral, and hence the turning performance of the plane. The center section has quite a bit of dihedral, but that is countered by the anhedral of the outer panels...evidently countered to much.

Mission scrubbed. This airplane won't fly as an R/C sailplane. It's a wall ornament.

Part 2:

For a long while, the plane hung up on my wall. There was no hope it would fly, so it's status as an ornament/hanger queen was assured. And yet...there was actually a tiny bit of hope. For you see, as a model builder, I am a perfectionist. There's just one problem: I'm just a mediocre builder. Every time I build a new plane, there always the hope that "this one will come out perfect...flawless." But, to be a perfectionist and also be a less than perfect builder means continual disappointment. There's always something that goes wrong...something that could have gone better. I imagine that truly great builders feel the same way when they finish a project...only their airplanes will still look better then mine!

Okay, so what, you ask, does all the preceding have to do with the Super Soarer? It's a few years later, on a rainy weekend afternoon, and I'm looking for something to build. I looked at the Super Soarer...I still did not actually know it's name yet. It was stuffed in the corner of a closet. I realized it was an airplane with nothing to lose. It wouldn't matter how badly I screwed it up, because I already knew that it wouldn't fly as it was. This was a plane with no risks. Perfection would be an airplane that could actually fly....time to build!

It was around this time that I finally learned what this airplane was. While browsing around on eBay, I happened up a plane for sale that looked just like mine, and it was called the "Super Soarer." With this valuable knowledge in hand I decided to ask a question on the Radio Control Soaring Exchange to see if anyone was familiar with this airplane. It turned out that Don Bailey, from Seattle, had actually taken a free flight Super Soarer and successfully converted it to R/C. He had enlarged the rudder and increased the dihedral, and reported that the plane flew great with just rudder and elevator control. It was really encouraging to hear that the plane flew well, but since my airplane was already built, there were some other changes I'd need to make.

There was one very obvious chore that needed to be done. If it was to fly, the Super Soarer needed to have ailerons. Using the "that looks about right" method, I determined the ailerons should extend from a bit past the outer panel dihedral break out to the wing tip. As with the original horizontal stabilizer, I had to cut off the trailing edge, then add a sub trailing edge where the aileron would go. The piece I removed from the trailing edge was to become the aileron. That was the plan. In reality, I again mangled the part that I was going to use for the control surface. Luckily, I was able to find some balsa aileron stock that was just the right size for the wing.

Somehow, I actually managed to make the cuts for the ailerons on both wings the exact same size. It appeared I could actually go on to the next step...installing the aileron servos, then test fly the plane! Yeah...well, there were probably about 20 other things I had to do before the plane would actually be ready.

First, I noticed the trailing edge of one wing was bent downward quite a bit. I spent about a week spraying ammonia on the wing and weighting it down with books. When I was done, the trailing edge had been bent to a fairly flat configuration....but a week later, it seemed to have drifted back to it's original bent shape. Oh well...the wing would be warped ("It'll still fly," I told myself).

With the wing in fairly complete form, I installed servo bays near the inner portion of the outer wing panels. The wing is quite thin out there, and the only servos that would fit were the tiny Cirrus CS-10 sub-micros that I took from my Mini Max park flier. This servo only puts out 7oz-in of torque, and that's at 6 volts. Since I was going to be running a normal 4.8 volt system, I worried if this servo would be enough. I decided to wash the numbers through the Multiplex Servo Torque Calculator to see if that would be enough. The calculator said I would only need about 3.4 oz-in at 40mph. That seemed rather optimistic, but I figured I'd give it a shot with the CS-10's.

These shots give a decent view of the
aileron modifications and servo placement.
The ribs on the outer panel used to extend all
the way to the trailing edge.

At this point I realized that the wing still seemed a bit too flexible. I took a really close look at how the wing was designed, and realized that the spar had no shear web what-so-ever. For those who've never built a wood wing, a shear web is usually a piece that is glued on the front or rear of the top and bottom spars. It's job is to tie the upper and lower spar together, and prevent them from twisting. This makes the wing stronger in torsion. Don Bailey helped out here again, and advised that he had installed shear webs all the way out to the wing tips on his Super Soarer. So, I set about installing 48 shear webs on the leading edge of the spar, from root to tip. This was very tedious, but well worth it, as the wing became noticeably stiffer and resistant to twisting. I also installed a large triangular gusset where the sub-trailing edge and trailing edge meet at the root of the aileron. I didn't do a good job with designing this modification originally, and felt the gusset was needed to tie the sub and trailing edge together.

With the wing structure done, I recovered it with transparent blue Monokote and then hinged the ailerons. My focus now returned to the fuselage. I reinstalled the original servos and did a bit of clean up work to improve the existing linkages. It took a few minutes of radio setup and about 5 ounces of lead in the nose to get the plane ready to fly.

The final flying weight was 27oz, with a wing loading of 11.2 oz/sq ft. So the big question was, of course, how the heck will this thing fly? I had little doubt it would fly, but looks can be deceiving. With those long transparent wings, I just couldn't help to think "floater." Then again, the wing loading was not exactly in floater territory. I really wasn't sure what to expect, but I knew one thing...I was done!

Ready to go...for the second time.

Flying:First flight took place on a fairly good day at the hill. As I got ready to launch it, I did get somewhat worried about being able to maneuver the Soarer (not that this would keep me from tossing it, of course). Visions of the intial test launches at the power field came to mind. Oh well, I had nothing to lose...I launched it and was instantly surprised. I had fully expected it to float out of my hand and leisurely drift into the slope lift. Instead, it very quickly gained speed and moved out over the slope. Next question...will it turn? Will it ever! The ailerons worked great. Roll response was crisp and there was plenty of authority. I flew back and forth across the slope a few times to get a feel for the plane. My impression was that it flew more like a "real" sloper then a floater. I was at first a little hesitant to let it pick up too much speed, but everything seemed to be working well, and I could not see the wing flexing too much. I got it going pretty fast in a dive, but I was still careful about pulling out to hard, or letting it get going really fast.

Another view of those gull wings

I never really contemplated doing aerobatics with this Super Soarer, but I was so encouraged by how it handled that I decided to go for it. The roll rate is very good...it's obvious that the little CS-10 servos in the wings have plenty of torque for this plane. It will loop too, though the twist in the wing tends to make it try and corkscrew as it comes over the top. The plane is fairly maneuverable, and it can make reasonably tight turns. However, I did find that it did seem on the verge of tip stalling in some cases. Most likely this is caused by a combination of the highly tapered wing tips and the un-floater like wing loading (not to mention the wing twist).

I guess one of the coolest thing is just how it looks in the air. Short of a scale Minimoa, there's not really anything on the slope that looks like it. Seeing those big gull wings from head on as it dives for the hill is an interesting sight. Of course, it's also always nice to see the sun shining through the transparent wings of a built up plane as it cruises at high altitude.

Finally, it was time to come in for a landing. Like most of my aileron slopers, I had set the Super Soarer up with spoilerons. They worked quite well, though I'm not sure they are really needed. With the little landing wheel, I felt comfortable coming in a bit fast and landing on the road, rather then in the grass. So, I brought the Soarer in for a cross wind landing on the trail. It bounced a couple times on touch down, and happily rolled too a stop several yards later....nice!

I'm still not entirely sure what category this airplane fits into? Floater? It's really too heavy for that. Scale? Well, maybe if you squint really hard and stand really far back. Sloper? It's not really fast or tough enough by modern standards to really be called a sloper. Does any of this matter? Nope! What matters is that this plane actually flies rather then sitting in the corner of a closet or garage...and it flies pretty darn well at that! What started out as a near disaster has turned out to be a fun and rewarding project. It still looks nice hanging on the wall though!

The end.

Updates:

I've been having a lot of fun with this plane recently, though it certainly has its quirks. It is often not an easy plane to fly. It really doesn't like light lift all that much, and the twist in the wing can really make it do some nasty things. I tried to do a straight ahead, wings-level stall and found that it would go into nearly a snap roll everytime. Consequently, I have to be very careful when the lift gets light.

The most fun thing to do with the Super are touch and goes. The little wheel just makes it too much fun. If the terrain at the slope is right, I can even manage to touch the ground and roll across the slope, still "flying" on the wheel, roll down hill a bit, and then take off again! I spent nearly half the day doing this once, and found that I had done a bit of damage to the underside. The wheel well had come loose, and there were some holes punched in the underside of the fuselage, under the nose. To repair it, I ended up tearing out the launch release mechanism (it'll probably never be used anwyay). I patched up the holes and reinforced the inside of the forward fuselage with heavy carbon fiber. It should be relatively bullet-proof now, so I can do touch and goes without worrying about it.



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