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What Our Members Are Building

Mike Pierzina’s Buttercup STOL

By Mike Pierzina, EAA 0635406, planecrazzzy@yahoo.com

Buttercup

Having already built a Kolb Firestar II, Mike Pierzina was researching his next project when the Wittman Tailwind caught his eye. Wanting something with the timeless good looks of the Tailwind but still being eligible for sport pilots to operate, Mike turned his fancy to another of Steve Wittman’s creations, the Buttercup. Mike has fallen head over heels in love with this able workhorse and is mixing Tailwind features into his Buttercup project.

I bought the prints to build aviation icon Steve Wittman’s remarkable speedster, the Tailwind. However, before I could scrounge the many materials it takes to build it, I found out about Buttercup, Steve’s earlier, lesser-known masterpiece. Among other things, Steve designed Buttercup as an easy-to-fly workhorse for carting spare parts, fuel, tools, and other necessities for supporting a race team efficiently. Buttercup was all of that: a breeze to fly, a good load carrier, economical, and fast enough not to hold up Steve’s racing schedule. It wasn’t uncommon to see Steve’s first wife Dorthy at the controls. Unfortunately Steve died before ever creating a plans set for others to follow.

Fast-Forward a Few Years
2009 EAA Tony Bingelis Award winner Earl Luce, an experienced Tailwind builder (and quite familiar with Steve’s construction methods), had been fascinated by Steve’s earlier design and had an opportunity to get close to the one on display at the EAA AirVenture Museum. Earl was able to painstakingly document the dimensions and construction details, making copies available to anyone interested. Once I found this out, I was hooked and almost immediately contacted him (www.LuceAir.com).

About this time, I got a deal on a set of unused Buttercup prints; however, since the two planes are cousins, my Tailwind prints still came in handy. Now that the Buttercup is becoming better known, some folks refer to it as the STOL Tailwind, and in fact, my project is a combination of the two, being part Tailwind and part Buttercup. I want slow-flight characteristics but with a fast Tailwind look.

Buttercup

Builder Support
Buttercup builders have a support group with an experienced cross section of people participating, some of whom are A&Ps, aeronautical engineers, or are in other related fields. This is my second aircraft build. I currently fly my first one, a Kolb Firestar II.

Buttercup

Basically, the Firestar project gave me the confidence to tackle this somewhat more complex undertaking. Nonetheless, we do have first-time builders at our forum. The Buttercup-STOL forum is increasingly active, and we now have over 1,000 building photographs and an active dialogue between builders concerning the many approaches to interpret Steve’s little work of genius, as brought to us by Earl. Also, as an additional help in sharing what I’ve learned, I’ve been keeping a detailed building log at Wings Forum.

Buttercup

Performance
Steve’s original Buttercup operated with less than 75 hp, and many builders are planning to follow Earl in using an O-200. However, I’ve upgraded to a Lycoming O-235, and I have a nice Catto composite prop as well. It’s pitched for climb performance which will help keep my Buttercup under the maximum light-sport aircraft (LSA) range. That’s an added bonus to this plane. It fills the LSA range.

Here’s a sample of the numbers produced by Earl Luce’s Buttercup.

Engine model

O-200

Engine horsepower

100

Propeller (pitch/diameter)

66/53

Cruise speed (75 percent power)

125 mph

Top speed (max continuous power)

145 mph

Landing speed

40 mph

Max speed (velocity never exceed)

150 mph

Stall (clean)

51 mph

Rate of climb

550 feet/minute

Gross weight

1,290 pounds

Empty weight

790 pounds

Useful load

500 pounds

Wingspan

29 feet, 5 inches

Wing area

132 square feet

Length

19 feet, 6 inches

Cabin height

44 inches

Fuel capacity

21 gallons

Seats

2 (side-by-side)

Cabin width

40 inches

Takeoff distance

300 feet

Landing distance

200 feet

Prints to build this plane are from LuceAir.

It’s amazing that Steve first flew his Buttercup in 1938. On far less fuel, it was faster than the production planes of the same era. It nearly went into production, but the war effort couldn’t be disturbed. Here’s a 1989 Sport Aviation article on the Buttercup written by the late Jack Cox.

Like many tube-and-fabric, plans-built aircraft, there’s a blend of time-tested assembly methods mixed with up-to-the-minute materials and techniques. Nonetheless, the price for the materials depends on resourcefulness and what the builder is willing to work with or willing to hold out for. I’m building mine pretty generically, but it will get me to the same little fly-ins, and maybe a casual cross-country or two – something at which the original Buttercup excelled.

Doors and side windows
Doors and side windows in place

I’ll have spent about $15,000 on my bird when it’s all said and done. But that’s with some serious bargain hunting. I’ve heard other builders plan to invest up to $30,000, but that’s mostly fancy glass, an autopilot, and a stack of radios (and maybe a stewardess for all I know). At this writing, I’m working on my cowl. It’s shaping up nicely.  

Fuel header tank
Fuel (header) tank in place.

Wingtips
The wingtips are a mix of wood and steel.

Feel free to visit our forum, even if you just want to look around. The Buttercup in its modern incarnation hasn’t been out there very long, but thanks to Steve’s original genius and Earl’s tireless efforts in making the plans available, it’s picking up in popularity. I suspect the main reason the Buttercup is undergoing a rebirth is because it’s such a well-designed plane, incorporating just enough novel features with sparkling performance to intrigue homebuilders.

Next time you’re at Wittman Field, swing by the collection of his aircraft on the flightline. You’ll be very impressed and glad you did.
 
Gotta Fly ...
Mike and “Jaz” the Flying Dog

Jaz the Flying Dog

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