Bad Mojo No Mo

A Pitts with a story to tell–and more to make.

Three times the Biplane Gold class winner, Smokin’ Hot, née Bad Mojo, is a seriously fast biplane. Had it not been for the radically modified Mong Sport Phantom redefining “racing biplane,” this white Pitts would be the runaway talk of the Biplane class. Best speed to date is a 224 mph race average.
(Photo: Tim O’Brien)

Airplane owners are caretakers, according to the more philosophical among us. Each man leaves his mark on the plane passing through his care before he and machine separate to others, and ultimately, their destinies. Anyone doubting this might consider our present exhibition, an intriguing white Pitts Special most recently named Smokin’ Hot and once again winning the Biplane Gold championship race at Reno last September.

Small is an advantage when speed counts and Smokin’ Hot is about as compact as Pitts architecture allows. Volunteer crewman Bob Brown (left) is a towering 6 feet 7 plus, which helps make the point, while owner Sam Swift (right) is still a full 6 feet. The open cabane/windshield relationship and thin wingtips show well here, too.

Stock Beginnings

The story begins in 1978 when a young Mike Ryer was awarded a certificate of airworthiness for the Pitts S-1S he had just built in Boulder, Colorado. Ryer constructed his Pitts for strenuous aerobatics in contests and airshows and in 25 years accumulated 3000 hours on the little sportster before slipping away from hardcore acro. There is little written record of Ryer’s time with his stock, red S-1S sport plane, other than an August 27, 1981, mention in The Steamboat Pilot newspaper. Documenting a local airshow with a three-paragraph bit surrounded by huge display ads for mundanely local businesses, The Steamboat Pilot noted, “Mike Ryer flew his high-performance Pitts Special to the delight of audiences…” We bet Ryer got a kick out of it, too.

What is documented is Ryer sold the Pitts to Bob Bryson in 2003. Not a race pilot, but “a big time Experimental builder,” according to later owner Jake Stewart, Bryson was the first to bend the S-1S toward air racing. Not afraid to make notable changes, Bryson’s ambitions stopped short of piloting around pylons, and instead he had pilots J.P. Thibodeau and later Leah Sommer and Mark Barber tend the stick at Reno. During Thibodeau’s time the plane was whimsically Son of Galloping Goat; Sommers and Barber opted for the less cheeky Son of Galloping Ghost. Both names undoubtably played off the P-51 racer Galloping Ghost, iconic for its Cleveland appearances and later coming to huge grief when crashed into the spectator area at Reno in 2011. But that was in the future in Bryson’s day.

First owner to speed-mod the plane, Bob Bryson retained the stock Pitts fuselage dimensions and weldment, but skinned the fuselage sides and turtleneck in carbon fiber. He also rebuilt the wings still in use today.

Bryson’s modifications included rebuilding, or more accurately, replacing, the wings. Using a Sparcraft kit, Bryson modified the airfoil to his own semi-symmetrical shape using custom-built ribs and clipping the wing assemblies to a seriously short 14 feet 2 inches. No doubt looking for aerodynamic stiffness, he then skinned the wings with carbon fiber, only to quickly remove the wonder material in favor of reapplying fabric covering. The four leading edges were also modified; normally skinned in thin aluminum or molded plywood (the latter stiffer but typically a test of a builder’s skills and patience), Bryson covered his leading edges with Kevlar he had shaped in a mold. He chose the yellow fabric over carbon fiber because Kevlar doesn’t shatter under impact loads (think bird strike) as does carbon fiber.

Additionally, Bryson removed all dihedral from the lower wings, which in turn necessitated longer interplane I-struts.

Handsome from any angle, Smokin’ Hot speeds up the usual frumpy Pitts lines by taking the sag out of the belly, sporting a tall Knight Twister tail and a narrow-entry carbon fiber cowling built by Jake Stewart in 2018–19.

Wanting to dispense with the draggy, externally braced Pitts tail group, Bryson amputated it in favor of a Knight Twister arrangement. This was a set of all-new vertical and horizontal surfaces built to Knight Twister plans and skinned in carbon fiber. The necessary mounting tabs were welded to the Pitts fuselage to accept the Knight Twister transplant and the result was a big increase in speed.

Another Bryson mod was this lowered, tinted canopy. Interestingly, both Jake Stewart and Sam Swift say the dark tint is never a bother and never even notice it.

Bryson also spiced up the engine a bit and was likely the one who replaced the original red paint with white, given that he had changed so much of the little Pitts’ surface area.

Next up was Jake Stewart, who bought the budding hot rod in 2013. Renaming it Bad Mojo, we’re guessing due to its frightening handling characteristics, Stewart continued upping the plane’s performance while adding user friendliness. And by user friendliness we mean Stewart made it so the plane wasn’t trying to continuously kill him. Our mouth sort of went dry when Stewart casually noted he did some engine work, “and I made a new mount to move the engine forward five inches, and it had a 4-inch prop spacer, which I changed to an 8-inch.” Holy aft CG, Batman! That would be fast, but oh so scary.

Asked how it flew with the CG tagging along like the red rag on the end of a load, Stewart gravely intoned, “You did not stall that airplane.” Then a pause, “It would not recover. The Knight Twister tail was too small in area…As I picked up speed it would tail stall in a race if I hit turbulent air and would nose down. And it would not recover until out of turbulent air.”

Looking back at the liftoff canopy at the same angle the pilot looks out when landing hints at the challenges of a chopped lid. Asked about visibility, Jake Stewart says, “Not very well! I slip it all the way to the runway, then straighten it up. Sam Swift added, “Visibility is horrible; you’re pretty much prairie dogging with that canopy.”
Payoff for the low canopy is reduced wind resistance through the choked cabane space. While there is a lot here with the cabane strut intersections, wires and much wetted area, the smooth transitions and general aero cleanliness of the build is also on display.

Bad Mojo indeed.

Summoning an aerodynamicist friend to run the numbers, Stewart enlarged both the horizontal stab and elevator so they were a little larger than the stock Pitts pieces, meaning they cast a noticeably larger shadow than the Knight Twister parts they started out as. This, along with moving the CG from 5 inches outside the rear end of the envelope to the correct zip code, did the trick. Stewart is now able to say the vertical tail is perfect, the rudder maybe a tad larger than it really needs to be and the pitch handling correct. He also opines the Knight Twister tail group dates from the 1930s and simply wasn’t designed for the 220-mph speeds a hot-rodded Pitts runs today.

Wearing just two ailerons on the lower wing, Smokin’ Hot “still rolls pretty quickly,” says Stewart. A specialized racer, it sees very little aerobatics. “I never did acro other than loops and rolls. It gained too much speed going downhill.” The small fillet on the lower wing is just one of many reasons why.

Winning Power

Besides getting the IO-360 Lycoming properly placed, Stewart gave it a thorough hot-rodding to reach its present state of tune. Pumping up the horsepower is de rigueur in the Biplane class because unlike F1, with its highly restrictive O-200 Continental mandate, Biplane rules allow engine upgrades and the high-drag airframes respond well to it. That makes Biplane a happy place for gearheads looking for some hot-rodding fun but not at the heroic levels associated with the Sport class.

Stewart added custom wingtips for the 2021 races because he was slowing 30 mph in the turns. These new tips start fully rounded then quickly taper to a thin edge, much like a pressure recovery wheel pant on its side. There’s also a touch of washout in the outer edge.

Stewart’s engine mods are underlined by a custom “semi-dry sump” oiling system. This is essentially a remote oil tank concept where oil gravity feeds—there are no scavenge pumps—to a tank mounted low on the firewall and shaped to aid cooling air exit the lower cowl opening. While bereft of any pump-powered crankcase evacuation advantages, namely enhanced piston ring seal and nearly eliminated crankcase windage (oil wrapped around the spinning crankshaft), the semi-dry sump is very simple, inexpensive, lightweight, easy to package and does reduce windage while giving the oil a break from frothing and heating inside the crankcase. Such systems are common in F1 monoplanes, and indeed, the late Jay Jones, an F1 racer from Buena Vista, Colorado, contributed substantially to Stewart’s oiling system.

Louvers and a tunneled cooling air exit on the belly—rare on biplanes—get the heat out efficiently. The landing gear is a gun-drilled aluminum Grove spring wearing Cheng Shin 11x400x5 tires normally found on RV-6A nose gears. This allows running RV pressure recovery pants.

The remote oil tank also shortens the engine vertically, allowing a tighter lower cowling for better streamlining. This advantage was augmented by building a custom cold-air intake system with 2-inch runners generated with some input from another of Stewart’s friends who just happens to have NASCAR intake design experience. Naturally, Stewart had to build a new cowling to take advantage of the engine’s tighter packaging, which was accomplished with the usual mountain of foam shaped into a plug to make a mold and finally the actual carbon fiber cowling layup.

We like the way Smokin’ Hot incorporates an ignition pointer in its engine baffling. The Light Speed ignition pickup is just behind the flywheel (orange wire) and the 8-inch prop spacer mainly hides in the nose bowl. It’s interesting how the breaks in the intake ducts are joined with leather and lacing.

The engine’s exact compression ratio is a team secret neither current owner Sam Swift nor Jake Stewart want to divulge, but Stewart said enough when he allowed the Lycoming has “extremely high compression north of 12:1. We’d go through about two starters a year!” That’s definitely a racy amount of squeeze, sufficient to move the engine into the accelerated overhaul timetable typical of specialized race engines. But that’s not really a factor as the plane doesn’t accrue too many hours a year, just the once-a-year racing plus enough time for the pilot to remain current.

Perhaps because it’s so efficient Stewart says, “This prop really loads it up; it’s slow off the line, the slowest I’ve ever been in. But once it gets going it hauls ass.” Current thinking is a three-blade should give better acceleration for Reno’s standing starts without hurting top speed. For sure this prop is a sleeping dog at the start, taking at least two laps to build up to speed.

Because of the increased rpm—3100 rpm while racing is typical—the camshaft specifications were changed to suit. This was done by slightly tweaking a Phase 3 Ly-Con camshaft. Ignition is provided by one magneto and a single Light Speed Engineering Plasma III system.

An engine this highly tuned would be a candidate for four-into-one headers, but Stewart specifically designed a custom two-into-one crossover exhaust because such systems tend to make more torque than long-tube headers in his experience. This also avoided a long, large-diameter, aerodynamically draggy tailpipe.

Besides giving a distinctive look, the Knight Twister tail “is way more effective than a Pitts tail,” says Stewart. “There’s more twitch in yaw and pitch” and it “never runs out of control authority.” All gaps are tightly faired or taped.

In what may be a Biplane class exclusive, the white Pitts runs something of a tunnel cowl exit built by Bryson. Stewart thought to expand on this and try an exhaust augmented cooling exit. He fitted a stainless steel heat shield, but as an expedient shot the aluminum rivets he had on hand instead of stainless rivets. During the test flight the aluminum rivets failed due to the heat—goes to show you what sort of forces are in exhaust—and the hot gas burned through the fuselage skin. This literally heated Stewart’s seat cushion and, “I made the fastest trip ever back to Denton, Texas.” The heat was bad enough, but the real danger was chemical. “I was feeling dizzy, and that cockpit has only a tiny vent. I put two fingers through it to scoop as much air as possible. You can’t open the canopy because it comes completely off…I lost three days of work to carbon monoxide poisoning.” The augmented cooling was abandoned.

All business, Smokin’ Hot’s cockpit is “actually very roomy” although we’re sure installing the liftoff canopy closes things up considerably. Biplanes and F1s often use liftoff canopies because they’re easy to streamline and there’s always a crew member around to help install/remove them.

Swift Going

In 2022 Jake Stewart sold Bad Mojo to fellow Biplane competitor Sam Swift. It was time for a change, says Stewart. “I don’t know. The racing just isn’t what it used to be. I won in 2021…it was more stressful than fun; the juice wasn’t worth the squeeze. I’ve got two kids now…and I had to burn up all my vacation to go to Reno. [If I race] I can’t take the kids to Florida or Galveston. I just wasn’t enjoying it as much.”

Meanwhile Sam Swift, who interestingly enough was flying another ex-Jake Stewart Pitts, a red S-1D, was wanting to speed up his racing program. Swift’s red ride featured light hot-rodding, but was well behind Stewart’s white racer when it came to speed mods. Knowing that buying an already hot-rodded airplane was easily a less expensive and labor-saving method of going fast than modifying the one he already owned, Swift kept after Stewart to sell him the white plane.

Most of Smokin’ Hot’s cockpit secondary gear is on the cockpit’s right. A handheld radio allows rudimentary communications, the empty RAM mount is for cellphone navigation and the red box is the Plasma III ignition unit. The blue accessory on the left floor is a fuel pump; the blue stains around the fuel valve say this isn’t the plane’s first rodeo.

As Swift put it, “You’re time and money ahead to buy an existing race plane than modify your own. You can work yourself up [through the racing ranks] by buying and selling airplanes.” It’s a strategy Swift has been faithful to, having started racing in 2016 in the red Pitts he had bought from Stewart. But the last several years Swift seemed stuck in fourth in the Biplane Gold race. “I couldn’t crack the podium.” Hence the move to the white Pitts.

Plenum cooling is the proven fast option for cooling race planes and Smokin’ Hot keeps things simple and tight with no access doors and rivets squeezing the panels together. Servicing access is labor intensive, but done before and after races when there is time.
It’s always amazing how much wiring and plumbing it takes to feed and instrument a simple four-cylinder engine. Oil cooling air feeds via the black duct off the right rear cylinder baffle.

And it worked. Mounted in the ex-Bad Mojo (now Smokin’ Hot), Swift had the Biplane field covered last year and he took the Gold win at 206 mph. This was Swift’s first Biplane championship and the airplane’s third as it took the Gold in 2014 and ’21, both with Stewart, plus the 2022 win with Swift at the stick.

Swift made no modifications to the plane in the short time he owned it prior to his 2022 win, so his plans are simply to “get more comfy with the airplane” and tease out “how to operate it most efficiently for racing.” He has no plans for major airframe mods. “That’s why I bought a different airplane…I’d have to spend thousands to gain the mods I did,” so expect to recognize Smokin’ Hot at the races for some time. Swift does plan on upgrading to a JPI 830 engine monitor while completely stripping out the existing instrument panel and rewiring the plane. His goal is to make Smokin’ Hot’s panel mimic his old Smokin’ Hot’s panel (see the naming sidebar) as he liked its layout and says it will be easy to duplicate.

His other plans are to freshen the engine, or at least some cylinder work, and build a lighter weight carbon fiber cowling, plus possibly try a different propeller—information the rest of the Biplane field didn’t want to hear, we’re sure.

So, if old Pitts never die but just go faster, it’s a good bet Smokin’ Hot will eventually have more owners in its future, along with more stories to tell.

Sam and Smokin’ Hot Paula Swift live in Nashville, Tennessee. A United 737 Captain, Sam finds time for the occasional tailwheel instruction. He’s also an A&P, so he comes by the hands-on part of racing naturally.

Photos: Tom Wilson.



Please enter your comment!
Please enter your name here

This site uses Akismet to reduce spam. Learn how your comment data is processed.