1/5th scale Gee Bee R2

Featured as a construction article in the August
2001 issue of RC Modeler Magazine

Wing span:  60" length:   37" Weight:  6 1/2 lbs. Engine: .60  2 stroke or .91  4 stroke Kit price: $169.95

Kit features: Fiberglass cowl Laser cut balsa and ply parts Black line rolled plan (2 sheets) Pre bent landing gear Top quality hardware Vac-formed ABS plastic parts Full color mylar decal sheet Illustrated instruction manual Click here to download the manual as a PDF
	This is the optional radial engine kit. It is very light weight and is intended for use when flying. It comes with illustrated assembly instructions.The radial kit is $12.00
These are the optional fiberglass wheel pants by Aeroglass. They sell for $38.00
	This is the laser cut fuselage frame. It is very quick to assemble and results in a very accurate fuselage with very little effort. The rest of the fuselage parts fit this frame so well that you have to see it to believe it. The wing features a full length laser cut spar with notches for the ribs that allows it to be built with unparalleled accuracy. Die cutting simply cannot match this level of precision or sophistication.

This model is the result of years of painstaking research. Although this is a sport scale model the outlines are very accurate and were taken from actual photographs of the full scale plane. Details like the correct number and spacing of the fuselage stringers has been used. The model has been simplified in two areas for quick construction; the wing incorporates strip ailerons and the wing fillets have been modified to allow easier building. The correct scale details of these areas are shown on the plan if you wish to build your plane to accurate scale detail. The plan also shows the correct placement of all numbers and decals, as well as many other scale details.

Flight performance is excellent. Top speed with the Saito .91 4 stroke  is approximately 70 mph. With a
14 x 6 APC prop my plane will break ground in 6 feet and climb straight up.

The problem faced by anyone who designs a Gee Bee is how to build the thing light enough for good slow speed performance. My design is much lighter than any other Gee Bee I have been able to find. Note the 25 oz. wing loading. As a result the slow speed performance is unlike any account of model Gee Bee flying I have read about. High speed performance is very smooth and hands off stable! Slow speed flight performance is gentle and predictable. The plane does not stall and recover...it just "mushes". Because the wing incorporates washout, it will not tip stall. Knife edge is accomplished with no aileron correction and very little rudder input. Roll rate is very realistic at the recommended throws. Landing requires a long low approach - and a three point touch down. I recommend test flying the plane on a day with a good breeze blowing down the runway. This will reduce the ground speed, "lengthen" the runway, and keep good airflow over the tail.

Most people think Gee Bees will be difficult to fly because they are short coupled. Nobody seems to worry about flying wing models though. Flying wings are so short coupled that they have no horizontal stabs at all! Actually Gee Bees are not as short as people think. The "fat" fuselage gives the illusion of a short tail moment. They are very close in plan form to the Sukhois.

A little R2 history:

The Gee Bee R2 was built in 1932 to win the Bendix cross country race. Jimmy Doolittle never flew it. The highest it ever placed in a race was 3rd. It was never raced at Reno. No one ever died in it.

The following is a portion of the construction article published in RCM magazine in August 2001. This is the first time this model was ever flown by anyone. The stress level is quite high on a new design that you have spent hundreds of hours developing!

The plane was fueled up and range tested, with no trouble found. The wind was dead calm which removes one variable. I ran the plane up and down the runway a few times at fairly high speed to get an idea of the takeoff roll. It seemed to want to go pretty straight. The guys at the field thought it looked like “Mission Impossible”.

The Saito .91 seemed to working OK so I lined it up at the end of the runway, took a deep breath, and opened up the throttle. I had air under it in about 50 feet, but it was kind of wallowing. Once I got it steadied out, I went for some altitude. Did I mention I was a bit nervous? The first part of this flight was pretty hairy. I thought I had a tail-heavy plane on my hands. The engine began to run very poorly about the same time that the R2 left the ground. A small amount of the adrenaline was wearing off, and I got ahead of the plane enough to realize that the CG was slightly aft, but the main problem was the control throws were about twice what I needed.  In the mean time the Saito was putting out about half power, which allowed cruising speed, but not much more.

 I flew a few circuits up high, and got it trimmed out to fly hands off. Then the motor quit. The field was extremely quiet…you could have heard a pin drop. I said something like “Oh, great.” but to my great relief the Gee Bee has an absolutely amazing ability to glide great distances with very little speed loss. I came over the end of the runway about 6 feet up and just rolled it into the weeds at the other end, some 320 feet away! It was a beautiful landing until I hit the weeds.

No damage was done, so I tried to fire it up to see if I could get the engine to work properly, but my remote glow clip had broken, and I had to give up. Someone said “Just take the cowl off and fly it like that” but I learned on an earlier Gee Bee design that the rudder becomes all but useless without the cowl, and I certainly wasn’t going there again.

The next flight was several days later. I moved the CG forward ¼ inch. I had reduced the throws 25%, and found a tiny ball of some kind of metallic substance on the glow plug. A new plug had the Saito working properly again. I also switched from a 13 x 8 to a 14 x6 APC prop.

This time when the Saito roared, the R2 left the ground in about 5 feet and climbed out straight up! The correct term for this is “adequate power”. I like it! Now I’ve got something I can work with!
I get up high and start to see what she’ll do. It rolls like it’s on a string, using just a touch of elevator while inverted. I’ve still got too much throw on everything. It snapped out at the top of the loop I tried.
I rolled it into a knife-edge and found I didn’t need any aileron correction to stay there. It took a very small touch of rudder to keep it up, and this was at ¾ throttle! I suspect that I could have snapped it out of the knife-edge with full application of the rudder, but I decided not to try that…yet. That funny little rudder is extremely effective. I did some slow speed tests next. This plane is a real floater! I know you’re thinking “Yeah, sure it is.” But it really is. At 6 ¼ lbs. The wing loading is about 24 oz. per square foot, but I think you have to add in a least another 100 square inches of area from the fuselage. This gets us into the 20-oz. range.

The other thing to note is that this is a very low drag airframe and it takes some time for speed to bleed off. The landing took a long approach, and took the entire runway.
This flight revealed that I needed to move the CG ahead just a smidge. I found that the plane “hunted“ a bit in pitch with the CG as it was. I decided to go home and make my adjustments, and check the plane all over for loose screws etc.

The next flights were made with CG moved ahead 5/8ths of an inch from where I started. I also reduced the throws on the elevator and rudder to 50% of the original settings. Now the plane flies very nicely. Ground handling is excellent and it goes down the runway nice and straight with very little rudder work. It also goes straight up from a 5-foot rollout. I let a few of the guys I fly with (all better pilots than me) have a go at the sticks and they all had positive comments on the planes abilities.
The only fault left was that it pulled towards the wheels in knife-edge, requiring up elevator input to track straight. After a small adjustment to the wing’s incidence, the plane tracks perfectly, both ways, with only rudder input.

The incidence change also made the R2 easier to slow down for landing. I can bring it in quite slowly, with the nose high and control the decent with the throttle.
I fly the landing pattern about 40 feet up and go a bit farther out than normal on the last leg. I’m guessing that I’m about 300 feet out on final at about 20 feet altitude. I then set up a nice glide and control the decent with the throttle. Once over the runway, I lower the tail a little and let the plane settle onto the deck on it’s own.

I went back to using the APC 13x8 and the plane goes a little faster, but still goes straight up for as long as you want. I also tried it with a 12x8 APC just to see if a 12-inch diameter fuselage would fly with a 12-inch prop. Performance didn’t really change much, but the Saito .91 was not really working right. It to produces more useful thrust at lower revs with the bigger props. I wanted to try an 11-inch prop, but I thought it might damage the engine so I quit while I was ahead.

Neat things you can do with a Gee Bee R2:

1. 5 foot takeoffs.
2. Straight up climb outs.
3. Almost hands off knife-edge.
4. Slow knife-edge.
5. Torque rolls.

I would like to thank my friend Michel Faizandier for his help in trimming the plane, using the NSRCA trimming chart. This chart is a list of flight test procedures and is used by pattern flies to get the very best performance from their planes.