Ultra Sport 40 ARF Flying

Great Planes Ultra Sport 40 ARF (Red)

July 28, 2007

Flew three very nice flights today. The aircraft handled and performed beautifully as usual.


November 24, 2006

I flew the UltraSport40 at the SPRC club annual Turkey Fly. The gear repair held up well and the plane flew great. I put in 3 flights today.

September 9, 2006

I repaired the right main gear and straighted up the left main just a bit. The left main gear wire was bent slightly in a cross wind landing early in the plane’s career.

August 26, 2006

1 short flight and I broke the right main gear out of the wing landing on the grass. Dohhh!

June 2, 2006



img_3797 I did 3 really nice flights with the UltraSport this evening. I love this airplane! It flies so awsome. It has enough power where you can roll inverted right after takeoff and continue your climb out, transitioning into an outside loop and topping out about as high as you’d ever want. But I also have a low pitch prop so I can start my approach at 1000′ AGL off the downwind end of the runway. Pull the throttle to idle, roll into a vertical dive, round out my approach towards the bottom, and she slows right down for landing. The low pitch prop at idle acts like a big air brake. I could put a higher pitch prop on and get a lot more top end speed, but I really like being able to keep my landing approaches under control.

May 28, 2006

I have been getting jittery radio performance out of the onboard system. I did some swapping and the only thing left it can be is the receiver. So this evening I purchased a new receiver and crystal. I hope this takes care of the issue because I really want to get this hotrod back in the air. Lately I’ve been only flying my Kadet and Cub which is relaxing and nice, but I’m feeling the need for speed!

October 16, 2005

I put in 3 more nice flights Suday afternoon after church while the girls were napping. I’m getting a bit more confident with it and bringing my manuevers closer to the ground and closer to me. As I can see them better closer in, I think everything improves. Big beautiful vertical manuevers with this one. I really like all the braking effect you get with the 11×6 prop at idle even in a 90 degree vertical dive. Replaced the spinner before the first flight and all is happy.

October 8, 2005

I flew the ultrasport for the first time in over two years. I remember it being really fast, especially on approach which made it hard to get on the ground. In fact I remember being just a little afraid of it, which is probably why I haven’t flown it in over 2 years. I initially installed an 11×7 prop, so I switched to an 11×6 and that seemed to make a huge difference. The braking action from the lower pitch prop helps slow the aircraft down at idle. This makes approaches much more managable.

I think I have a near perfect combination for this airplane: an OS 46FX turning an 11×6 prop.

Looking back on some of my earlier comments from 2.5 years ago, I can see that I have a lot more flying experience since then with a variety of airplanes. This is still my biggest hotrod, but the 11×6 prop really helps tame the landings.

It still really scoots, even with the 11×6. I think it has better acceleration off the ground and I think a bit better vertical. I really like it’s straight tracking through just about any maneuver. I’ve never met a plane I didn’t like, but this one might be my new favorite! (for now.) 🙂

I need to straighten the right main gear wire from a cross wind touch down 2 years ago, and one screw on the spinner stripped out. One of these days I should finalize the cowl installation.

May 19, 2003

It’s my birthday again today, so I can say that I was able to successfully assemble this ARF and fly it in the space of one year. 🙂 I’ve put a couple more flights on last week, and it is a joy to fly. If I push out my downwind leg further away from myself, that gives me more space to do a gentler turn to base and final. This helps make the approach and landing much more smooth and solid. Initially, I was trying to crank her around too sharp on my turn to base/final and was loosing a lot of altitude and doing a lot of pitch oscillation. That didn’t hurt anything, but probably gave any observers a few white knuckles, not to mention myself. 🙂 I’m new to such a high performance aircraft, but I’m learning! If you can learn the basics on a trainer, and get up some confidence and experience in an intermediate aircraft, this one is a *blast* to fly. It took me 20 years off and on to get here, but it’s a lot of fun. I was going to sell my old sweet stik on ebay now that I have the ultra sport flying, but I’m semi-tempted to recover it and restore it … it still is a sweet flying airplane.

May 07, 2003

I was waiting for the perfect day, but the weather and my schedule were not intersecting. But, the winds didn’t seem too bad today so I packed her up and headed to the field. It’s always 5-10 mph windier at the field than the weather report from the local airport but it was mostly down the length of the field so I fired up the engine and blasted off. It was further out of trim than I was expecting, but within the range of my trim adjusters. The .46FX really hauls it across this sky. This is a slick quick bird. Very nimble and has a very light feel. I can make this thing do things my old sweet stik could never quite do. I’m no kind of aerobatic pilot, but I can flail around the sky and usually stay above the deck. She can almost fly verticle, but tough to do much of that in the really stiff wind we had today. I chopped the throttle to test slow flight characteristics. It’s very nice at slow speed, and I could haul back pretty far and it would just float along, so I pulled all the way back and she almost instantly stalled and did a decisive snap rolled. There’s lots of rudder authority to waggle around the tail with. I’m not sure what their called, but it’s alot of fun to do a high speed pass, pull up and go vertical, chop the throttle and as she comes to a stop, go full rudder to nose over. This leaves you in a dive and if you pull out, you are coming right back at yourself. This move is fun power off or power on. I was pretty tentative in my flying given the wind and the first flight jitters, but all in all a really nice bird.

Landing is something I need to practice more. The ultra sport is a *lot* faster than my sweet stik, and drops the nose a lot more in a sharp turn. It also does a really nasty snap roll on stall. I’m not sure it’s possible to stall the sweet stik. I wonder if I fly my down wind leg a lot further out if that would give me more space to do a gentler turn to base/final? My landings were all mostly successful, although I’m shakey in the turn to base and final. For one landing I got hit with a decent cross wind gust right as I was planting the mains. Both main gears are bent a couple degrees to the left … oh well, that should be an easy tweak.

I think for the most part I can get her up and back down safely, even in a pretty choppy and strong breeze so now I just need to practice, practic, practice. 🙂

May 02, 2003

Late Friday afternoon I ran two tanks of fuel through the OS .46 FX engine to begin the break in process. This is an awsome engine and really generates a *lot* of power (especially compared to the old K&B .40 I bought in 1981.) Saturday morning I was prepared to try a first flight, but it ended up being pretty windy with gusts up to 25 mph so I passed. I did take my new/old super sportster 40 up for a spin, but didn’t fly for too long … it just wasn’t the greatest combination of wind direction vs. sun angle. (I removed some nose weight from the SS40 and I think it behaves a bit better and has a little bit gentler feel to it. It’s a bit tail heavy according to the instructions, but flies more like it is overly nose heavy.)

Ultra Sport 40 Assembly

Great Planes Ultra Sport 40 ARF (Red)

Initial Comments

This was my b-day present for May, 2002. My super sportster 60 construction project has been mostly stalled so I thought I’d see how things fared with an ARF. By the time my Super Sportster is ready to fly, I’ll have a large time/emotional investment in it so I would like to have some low wing tail dragger time in the log books before I actually try to fly the Super Sportster 60.

The skin of this aircraft is interesting. Typically, kit construction has you building up some sort of frame and then sheeting over the top of some or all of the structure with thin balsa sheets and finally covering with a thin plastic heat shrink film. This ARF takes a different approach. Instead of balsa sheeting they have a thicker layer of covering that is made of some dense foam laminated with a thin plastic external layer. This plastic/foam sheet wraps around the underlying structure (which can be rough cut because it doesn’t show through the foam layer) and has “cool” designs printed directly on it, so there is no need for painting or decals. All in all it’s about 1/8″ to 3/32″ thick or so and structurally significant. The wing for instance is built up with standard wing ribs and stringers, but then wrapped with this foam/plastic composite instead of sheeting with balsa. The advantages I see are that it is light, probably cheap, and you can directly print your cool color scheme to it. The disadvatage is that if you ever ding it up significantly, I’m not sure how it could be repaired. There are a lot of plastic pieces on this plane in addition to the plastic/foam sheet covering. If you crashed and did any kind of substantial damage to this airplane, I think you’d have to toss the whole thing. Especially since it is discontinued so you probably can’t find replacement parts for it.


I’ve just begun construction so I’ll share some thoughts and photos as I go. I don’t have a separate work shop so my work area is very tiny and shared with the rest of the family. My apologies for the clutter in these pictures. 🙂

This is my first ARF. Generally construction is straightforward. Things always take longer than you hope/plan/expect, but the sorts of things you need to do with an arf, you would have to do anyway with a kit, and the arf saves you building up the major structures.

Things don’t always fit together perfectly, so expect to shave a bit off here and there and do a good amount of sanding. The box says sanding is not needed, but the instruction manaul correctly says otherwise. I have a power sander I bought for a house project which actually works very well for the various sanding chores. Even with ample sanding, it’s hard to get everything to go together just perfect. Oh well, hopefully it will be good enough, and I’ll just slop a little extra epoxy in the cracks. My assumption is that with no extra sanding (as per the claims on the box) I would get a functional and safe plane, and any tiny discrepancies may affect looks and perhaps subtly affect tracking through the sky, but I don’t think it should be a safety issue.


05/20/2002 – Here are pictures of the wings. The two halves are joined and the landing gear is installed. I’m sure this hotrod will fly as fast as I need it to go, so I opted for the simpler, fixed gear installation.


wing2 05/20/2002 – Just for fun I placed the fuselage on top of the wing to see how things are shaping up:


test-fit2 05/22/2002 – I glued in the wheel well covers and the top and bottom wing fairings, as well as the front dowl (for securing the front of the wing) and some foam to seal the exhaust residue out. The wing is almost done with the exception of installing the aileron servo and lincages.

05/23/2002 – Doh!!! First major setback. Once the wing is assembled, you need to mount it to the fuselage. This ARF uses a single dowl in the front of the wing and two nylon bolts in the back. The dowl is installed in the front, center of the wing during wing assembly and the corresponding hole comes predrilled in the fuselage. The problem is that it doesn’t fit right. (Or at least my resulting wing didn’t fit right.) The wing chord is too long, or the dowl mounting hole is too high, or a combination of both. The fuselage has major structural bulkheads on the wing front and back, so the fuselage opening can’t easily be made bigger. So I carefully sliced open the plastic wing fairing in the back of the wing and started hacking away balsa and plywood from the trailing edge. I also got out my knife and worked on lowering the front dowl hole a bit. I probably need to close off the top of the hole with some sort of filler so there isn’t any opportunity for movement of the dowl. However, the wing is already so tight against the saddle in the fuselage that I doubt that could ever happen. I don’t know what this is going to do to the wing incidence, but I suppose I should check/measure before I fly the thing. (Update: I never got back to checking the wing incidence, but she flies pretty great as constructed.)

05/24/2002 – I finished installing the aileron servo and lincages and did a bit more carving to get the wing to fit better. I think the wing is pretty much done. The powerplant hasen’t arrived yet, so I’ll just skip working on that end of the fuselage until it comes. Next up is the wing mount.

aileron-servo 05/25/2002 – Finished the wing mounting. I was a little nervous about the two main wing mounting bolts. I tend to have a hard time drilling holes that line up when I’m done, but in this case I followed the technique outlined in the manual and everything worked great. Next up are the horizontal and vertical stabalizers.





05/27/2002 – Working on mounting the horizontal and vertical stabs. I followed the instructions and things seem to be progressing in a straightforward manner. The structure is pretty chinsey/weak back there though. I can see why they add two aluminum brackets to reinforce the horizontal stablizer. And then the plastic fairing around the base of the vertical stab also is a significant structural component. It makes me a little nervous, especially compared to other kit’s I’ve built, but I’m proceeding with faith in the instructions. This will be a very sharp looking aircraft, but not one you want to bang up. It has very light weight construction. (Update: after putting the tail together completely, it came out very sturdy. The braces make a big difference. All in all, this is as solid as any other kit I’ve built.)



vertical-stab In this next image I have the rudder and the vertical stab fairing positioned, but not glued. Next up is the tail wheel.

tail 05/28/2002 – Except for the control lincages, I finished up the tail. This involved gluing on the fairing for the vertical stabalizer. This fairing is a major structural component so it needs to fit and be glued securely. However the instructions were careful to point out that the horizontal and vertical stabs needed to be slid back far enough so that the rudder line is flush from the back of the fuselage to the back of the vertical stab. This unfortunately meant that the vertical stab fairing wouldn’t fit correctly. I hacked on it and chopped off a bit from the back until it would fit flush along the sides and the front. This means it isn’t quite as pretty, but it should serve it’s structural duties just fine. (Update: once everything is together, this blemish is almost impossible to notice.)

I then proceeded to install the tail wheel and rudder.

tail-wheel Then I proceeded to install the horizontal stabalizer braces. These actually add a lot of support and structure.


Finishing up …

04/30/2003 – Ok, finally, I made some time to do a bit more work. I’m so close, I just need to push through and get it done. Recently I’ve installed the control lincages, installed the fuel tank, and installed the engine. The two major remaining items are to install the cowl and the canopy. I might do the initial flights with the cowl off? That OS .46 Max sure swings a big looking prop … 🙂