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Raceair Designs' Lil Bitts Biplane

Photos and story by Ed Fisher, EAA 64715

Lil Bitts

Ed Fisher grew up in an experimental aviation atmosphere - his parents were both aircraft builders, so it was natural that he would follow in their footsteps. Ed has been building and designing aircraft since the mid-1970s. He has been involved with pylon racing and has been employed in the field of aviation most of his life. A two-time Oshkosh Ultralight Grand Champion award winner, 1991 and 2004, Ed has also restored many aircraft and keeps this activity alive today in addition to his lightplane designs. A native of northeast Ohio, Ed relocated his operation to Sebring, Florida, to better serve the growing light-sport aircraft industry, but he has since found better digs in Gilbert, South Carolina. -Pat

Almost everybody loves a biplane. Small ones are cute, easy to store, attract loads of attention, and sometimes cost less to build than conventional, full-sized aircraft. Over the years I have built several biplanes, some from plans and others as original designs of my own.

Back in 1993, I was developing an ultralight midget biplane for amateur builders. I envisioned a gaggle of ultralight replicas of popular midget biplanes. In designing the Micro Mong from the lines of the Mong Sport biplane, I also sketched a Smith Miniplane look-alike and a Pitts S-1C variant. I noticed how similar the fuselage structures of the Mong and the Pitts were, as the truss layout was almost identical save the fact that the Pitts’ fuselage was 4 inches deeper than the Mong’s in the cockpit area.

While fully developing the Micro Mong and flying it at Oshkosh 1993, I also sifted off some time to weld up a Pitts “type” fuselage, re-engineered to be dramatically lighter than the stock S-1C. It looked interesting, and I actually contacted some representatives from the International Aerobatic Club to see what interest there might be in a new, entry-level, lightweight biplane for kit construction. I hoped this would give the members a lower-cost alternative to what they were currently flying in competition. I didn’t get much in the way of positive response from the club, so I worked on it a little more and then hung it from the ceiling, eventually selling it to move on to other things.

FAST FORWARD ABOUT 10 YEARS
I found myself the owner of that bare fuselage again and could not resist playing with it. There was new purpose in building it now, as rumblings of “sport pilot” rules were on the horizon, and beefing this airframe up a tad would possibly result in a fairly potent 450-pound aerobatic biplane. I thought that, if a standoff scale Pitts-type machine could be built and marketed as a 49 percent complete kit with all welding and complex forming done, a real market may exist for the active Pitts pilot who, for whatever reasons, may want to let his or her medical expire but still fly a sporty machine as a light-sport aircraft.

Fuel economy was an issue as well, as the little engines I intended to use would burn one-half to one-third the fuel that a big Lycoming does. I needed to finish the project with the nostalgia and spunk of the Pitts Special, so work began in earnest on what I called Lil Bitts. It did not take long to design and build the wings, controls, and tail surfaces, but in mid-2005 progress was delayed while I relocated my fabrication and restoration business to south Florida. To raise funding for the relocation, I had decided to sell off several projects, and my flyable Mong Sport and Zipster biplanes as well as the Bitts were all on the block. A friend purchased the 98 percent finished Lil Bitts, with an agreement that I could buy it back in the near future if he should lose interest in completing the project.

Cowl

That chance came, and in January 2007 I found myself once again towing the project home. Feverish work on the airplane continued in February and March, since I wanted to debut it as flyable at Sun ’n Fun in April, so I built up cowlings and wheelpants, finished radiator plumbing, and dreamed up color schemes. My wife, Val, and I began the detail-oriented wet sanding, spraying, and masking for the three-color paint job, reminiscent of the original Betty Skelton Little Stinker design, since it was both colorful and historic.

Paint

Paint

We certificated the aircraft as an experimental light-sport aircraft and began the taxi testing. My first flight in the airplane from Sebring, Florida’s north-south runway was uneventful, other than a slightly high water temperature after about 10 minutes. The Rotax 582 was performing well. Control harmony was balanced between rudder and elevator, with the ailerons, which were not yet gap-sealed, a bit less responsive. The climb performance and cruise speed exceeded my expectations, and any thoughts of it not being competitive were quickly forgotten. Flying almost every day, we sorted out cooling issues and prop pitch changes to arrive at the best combination.

THE UNVEILING
We took it to Sun ’n Fun 2007 and were guests of D&E Aircraft of Florida in its booth to show it to the world. We talked to many interested people and were honored to receive the Experimental-Class Best Fabric award.

We have more than 38 hours on the machine now, and it is a blast to fly. Firewalling 64 horses and seeing a more than 1,700 fpm rate of climb is incredible, but pushing the nose over to level flight will wind the airspeed up to about 109 mph with the current pitch adjustment on the 71-inch diameter Warp Drive prop.

Paint

ENGINE
The airplane was originally designed around the air-cooled Rotax 503, but we are currently using a 64-hp Rotax 582, a two-cylinder, two-cycle, liquid-cooled engine with dual Bing carburetors and a C-type gearbox with 3.2-to-1 ratio. The motor mount, mount plate, propeller, and cowling can accommodate either engine.

People ask me if the Rotax 912 series might be a good match, and my reply is that the engine, although it would work great, would be heavier than the aircraft was designed for, would be far costlier, and dealing with the dry sump oil issue would complicate things on an aerobatic aircraft. As is, the airplane weighs 432 pounds with a starter and mechanical brakes. The airframe is stressed for a g load of +6 and -3, and some static load testing has been accomplished on various components.

The wings are larger than you would see on a stock Pitts S-1 and have more chord and span. To build an airplane that weighs about 50 percent of the subject airplane you’re replicating requires careful repositioning of various components to keep it flying well without destroying its good proportional looks. The Rotax engine weighs almost 100 pounds less than the customary Lycoming that powers a Pitts, and since you can’t scale down the pilot, you must be creative in wing stagger and sweep to get the pilot closer to the center of gravity (CG).

Cockpit

CONSTRUCTION
Construction of the fuselage and empennage is fairly typical with tubing sizes from 3/4-inch down to 1/4-inch, and 4130 alloy is used throughout. The wings are built with robust 0.125-inch-wall tubular front spars and 0.0625-inch-wall rear spars, and they employ my proven “widget and rib angle” wing rib construction method as used on several of my designs over the years.

Wing structure

The rigid V-type landing gear was moved aft of the Pitts location 4 inches at the axle centerline, since the ground CG had to be adjusted for the much lighter engine. Heel-type Azusa brakes are employed, but future versions will incorporate hydraulic brake assemblies.

Since the original intent of the design was to provide a 49 percent complete, experimental amateur-built (EAB) kit, small fabrication and fitting projects will be left to the builder, including final fabric covering and painting. Raceair Designs has a builder-assistance program outlined for those who need extra assistance.

Done

The prototype, N18LB, is certificated in the experimental light-sport aircraft category, easily fitting this category in all regards. So, at this point, the only option is EAB. We are currently offering an airframe kit that fits the strict definition and spirit of EAB, at an introductory price of $19,900. This price, of course, does not include engine, instruments, or paint.

For further information about the Lil Bitts program, contact Ed Fisher at 330-518-8383 or e-mail raceairdesigns@hotmail.com.

Wingspan

19 feet, 4 inches

Wing area

112 square feet

Fuselage length

15 feet

Height

5 feet, 7 inches

Empty weight

432 pounds

Gross weight

800 pounds

Useful load

368 pounds

Wing loading

7.1 pounds/square foot

Takeoff roll

300 feet

Climb

1,700 fpm

Cruise

95 mph indicated

Stall speed

39 mph indicated

Top speed

109 mph indicated

Stress

+ 6g and -3g

Fuel capacity

12 U.S. gallons

Here are the specifications for our prototype, N18LB. Performance figures derived on a standard day with a 190-pound pilot, 4 gallons of fuel, Rotax 582 C-box engine, and a 71-inch Warp Drive, ground-adjustable propeller.

 
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