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YOUR HOMEBUILT AIRCRAFT AUTHORITY 

Kitfox Super Sport 

New Take on an Old Favorite: 

O-233 Lycoming · Spiffy Mods · Full o' Beans! 

The Myth of Bug-Free 

Avionics Software 

® ® 

February 2012

Kitfox Super Sport 

A new American engine joins an American aircraft icon. 

By Marc cook 

8 KITPLANES February 2012 www.kitplanes.com

With the Lycoming O-233 on the nose, the Kitfox Series 7 Super Sport takes on a pert, compact appearance. Although Kitfox Aircraft 

had the older Lycoming O-235 as an optional engine for this airframe, making the 233 an ideal fit took a decent amount of work. 

As often as this particular Kitfox 

seems to get new engines (this very airframe, 

now housing the Light Sport 

Aircraft-intended Lycoming O-233, 

once grasped the Rotec radial), you’d 

think something was up in Homedale. 

It’s possible to imagine that this thrumming 

little shop on the western bank 

of the Snake River in Idaho has a huge 

machine extruding firewall-forward 

packages as fast as new engines can be 

found, like an overgrown Pez dispenser 

of internal combustion. A giant crane 

removes one powerplant from the airframe 

(still warm from a test flight), sets 

it aside, and grabs another. The propulsion 

package lands home with a thud. A 

complex quick-release system instantly 

marries the new engine to the Kitfox’s 

simple airframe with a clack that would 

do coupling train cars proud. 

Meanwhile, in some dark corner, 

Kitfox Aircraft owner John McBean 

cackles in delight, a countrified Dr. Evil 

in blue jeans and a flannel shirt. His 

machine is alive! 

The Reality 

McBean only wishes he had such a 

machine. In fact, his penchant for 

sampling new and different engines 

on the front of the Kitfox represents 

a massive amount of additional work 

for his small staff. “But we have to try, 

don’t we?” he asks in his best workbootrhetorical 

tone. Like many manufacturers, 

Kitfox has to watch the bottom line 

Photos: Marc Cook 

carefully, so R&D projects using truly 

unusual engines or offbeat configurations 

just aren’t part of the day to day. 

“We’re open to trying a lot of things,” 

says McBean, “but in the end we have to 

sell and support the design.” Even if it’s 

technically not the company’s engine, 

Kitfox inevitably gets dragged into 

powerplant-related customer-assistance 

issues. Better, in this case, to go with 

what you know. 

Which is why the Rotax 912S has 

become the default choice for the Kitfox 

Super Sport. The overwhelming majority 

of the kitbuilt S7s in the world have 

the Austrian engine, and all of the 

factory-built SLSAs do. But that didn’t 

stop McBean from trying the Rotec 

seven-cylinder radial. (See “Kitfox with 

a Rotec,” KITPLANES® March 2011, 

Page 8.) That airplane was a huge hit 

at AirVenture 2010 and caused many 

historically inclined pilots to stop and 

gawk. McBean admits the Rotec was a 

sentimental project, one not expected to 

threaten the sales of the Rotax Kitfox. 

But he was right that it drew attention 

to the airplane and to the company. 

Now there’s a Lycoming. A new 

Lycoming. OK, mostly new. Introduced 

in 2008 and finally released to the 

marketplace in early 2011, the O-233 

The gray goods: Lycoming’s new O-233 is a refined version of the popular and enduring 

O-235. It makes 115 horsepower in this installation. 

KITPLANES February 2012 9

Kitfox Super Sport continued 

is Lycoming’s response to the Rotax 

912 and a rejoinder to the Continental 

O-200-D Lightweight, both of which 

have proven to be popular LSA engines. 

(The Rotax much more so because it has 

a massive head start, particularly in LSA 

designs with extra-American roots.) For 

this project, Lycoming started with the 

long-running O-235 four-cylinder, aircooled 

engine and ran it through an 

aggressive weight-reduction program. 

Jenny Craig for powerplants, only with 

CAD-CAM and an angle grinder in 

place of freeze-dried food and diet tips. 

(For more on this engine, see “Engine 

Update: Lycoming’s Light-Sport ready 

O-233 arrives,” Page 42.) 

Kitfox SerieS 7 

Super Sport 

Price ............................................................................ $23,185* 

Estimated completed price ..........................$35,000 - $60,000 

Estimated build time.............................................. 1000 hours 

Number flying (at press time) .......................................... 3800 

Powerplant ..................... Lycoming O-233, 115 hp @ 2800 rpm 

Propeller ................WhirlWind two-blade, ground adjustable 

Powerplant options................................................................... 

Continental O-200/IO-240, Lycoming O-235, Rotax 912/S 

AirfrAme 

Wingspan ................................................................... 30 ft 8 in 

Wing loading ........................................................ 9.57 lb/sq ft 

Fuel capacity....................................................................27 gal 

Maximum gross weight ................................................1320 lb 

Actual empty weight .......................................................868 lb 

Useful load.......................................................................452 lb 

Full-fuel payload .............................................................294 lb 

Seating capacity ......................................................................2 

Cabin width .......................................................................43 in 

Baggage capacity ............................................................150 lb 

perfor mAnce 

Cruise speed ....................................... 123 mph (107 kt) TAS ** 

7000 ft @ 75% of max-continuous, 6.5 gph 

Maximum rate of climb .......................................... 880 fpm ** 

Stall speed (landing configuration) ............ 41 mph (36 kt) IAS 

Takeoff distance ......................................................... 290 ft ** 

Landing distance ........................................................ 290 ft ** 

Specifications are manufacturer’s estimates and 

are based on the configuration of the demonstrator 

aircraft. 

* Kitfox Aircraft has not completed full testing for 

the O-233 package and has not set final pricing for 

the specific kit components. The listed price is for the 

similar O-235 installation package, less engine. 

** These performance figures are for the 100-hp 

Rotax version of the Super Sport. 

McBean approached Lycoming to be 

one of the early adopters of the 233 after 

the engine was introduced at Oshkosh. 

“I liked what I saw of the 233,” he says, 

“and I’m always willing to try new 

things. Plus, I was eager to have an 

American-made engine.” He’s quick to 

praise the Rotax for its low weight and 

overall good reliability record, but you 

also catch a glint of a red, white and blue 

undershirt beneath his Cabela’s flannel. 

This would be a new relationship for 

Lycoming and Kitfox under the current 

ownership, but the airplane and 

the engine go way back. In the time of 

the Kitfox’s rapid ascendancy, SkyStar 

Aircraft, which had purchased the company 

and the designs from Dan Denney, 

looked to expand the airplane’s appeal. 

That desire resulted in the Kitfox Series 

5, a significantly larger, beefier and 

more “grown up” Kitfox than the ones 

that started on two-stroke powerplants 

and a waif-like structure. The Series 5 

was designed for the then-new Rotax 

four-strokes, sure, but it was also meant 

to take the small four-cylinder Continental 

and Lycoming engines. Many 

were built with the Continental O-200 

and the Lycoming O-235, the latter an 

engine that could be readily found in 

the remainders bin. 

Then and Now 

It sure would have been nice if the O-233 

had slipped right into the firewall- 

forward package designed for the 

O-235, but that was not the case. 

The propeller shown here, a first-test example from WhirlWind originally intended for the 

Continental O-200, has been replaced with a Catto prop with greater diameter. Kitfox is 

still testing to find the best prop for this airplane. 


To speed development, Kitfox used an 

existing O-235 cowling as a template, 

hence the bump. It’s likely this feature will 

disappear in the final cowling for the 233. 

Dual exhausts emerge ahead of a turned 

metal lower inset. A small lip on the outlet 

improves cooling, which was absolutely 

not an issue during the test flights. 



McBean and company decided to make 

some minor modifications this time 

around, taking advantage of some of 

the 233’s intrinsic benefits. For example, 

with the Champion-built electronic ignition 

replacing magnetos, the back of the 

engine is much less crowded, especially 

so considering that few builders opt for 

a traditional instrument vacuum system. 

Even though the 233 was supposed 

to be much lighter than the 235, it still 

promised to be heavier than the Continental 

(by a little) and the Rotax (by a 

lot), so it made sense to move the engine 

rearward in the airframe. The 233’s new 

layout made this alteration possible. 

Originally, McBean wanted to move 

the engine aft 2 inches, but settled on 1.5 

inches as the best compromise of weight 

What’s in 

the Box 

Kitfox Aircraft breaks the Super 

Sport kit into four major segments. 

Fuselage, wing and landing gear 

make up the firewall-aft part, with 

a second kit for the engine/firewallforward 

components. Currently, Kitfox 

sells the Super Sport kit for $19,985 

firewall-aft. To that, you’ll need to 

account for the engine-component 

kit. The Lycoming O-233 has not been 

priced, but the FWF package for the 

Rotax 912S runs $4295 and the kit for 

the O-235 runs $3200. The aft portion 

includes the 4130 steel-tube fuselage 

cage (add $650 for powder-coating) 

with all the fittings in place for either 

trigear or tailwheel configurations. 

Also included in this kit are things like 

seat shells and shoulder harnesses, 

windshield and side windows. The 

wing kit can be had in basic form or 

as a quickbuild (add $1350). Engine, 

avionics, interior fabrics, covering and 

paint are extra. 

—M.C. 

placement and firewall access. Shifting 

an engine is not a trivial process. 

McBean had to create an all-new engine 

mount, have an entirely new exhaust 

system crafted (it’s a conventional double-crossover 

system with shrouds for 

cabin and carburetor heat), rework the 

carburetor mounting system and airbox, 

and accommodate a lightweight 

starter and alternator. Oh, yes, plus do 

an entirely new set of rigid baffles. That, 

and create a new firewall-forward wiring 

harness and find room for the ignition 

coils on the cool side of the baffling. 

Trivial stuff, really. 

Covering this engine is a cowling 

loosely based on the Kitfox/235’s. “But, 

you know,” McBean says, mentally reliving 

the process, “that’s a compound 

curve all the way across the cowling, so 

slicing an inch and a half isn’t just taking 

a bandsaw to it. Plus we had to adapt 

it to the new design fiberglass boot cowl 

that wasn’t around when the first 235s 

were done.” Every time you think these 

airplanes are modular, reality kicks you 

in the kneecap. 

Lycoming, for its part, has been 

extremely supportive, says McBean. 

“We have a conference call every week,” 

he says. “They want to know how the 

engine is performing, what kind of tem- 

peratures I’m seeing, everything. It’s 

been a terrific relationship.” Lycoming 

deferred to the Kitfox factory’s expertise 

regarding the powerplant installation, 

though it did provide substantial documentation. 

While Lycoming believed 

that the engine would have been fine 

without an oil cooler, McBean learned 

otherwise; a compact cooler is now part 

of the firewall-forward package, nestled 

on the firewall ahead of the copilot’s 

feet, fed cool air from the upper baffle 

area behind the No. 3 cylinder. 

Lighting the Sparkler 

The version of the O-233 flying on the 

factory Kitfox isn’t the most advanced. 

While it packs the electronic ignition, 

it doesn’t have the fuel injection that 

Lycoming planned to offer (and does 

for the Experimental crowd). Even so, 

McBean confesses that the ignition 

arrived barely in time to make Oshkosh 

last year. Showing some real development 

savvy, Lycoming provided spares 

for the ignition system, appreciating 

that McBean would be short on time to 

fine-tune the installation before heading 

across the country. Rather than it being 

an admission that something might go 

wrong, this move by Lycoming was brilliant. 

Don’t read it any other way. 

Lycoming has set aside the option of fuel injection for the ASTM-approved LSA engine, 

so the Kitfox wears a conventional carburetor and a slick NACA duct feeding it. 


In the time since the airplane’s return 

from AirVenture last summer, it’s been 

flown almost daily in the quest to vet the 

engine, beat on the systems, and find the 

best propeller for overall performance. 

“It’s been a great engine,” McBean says. 

“We’ve worked it very hard. It hasn’t 

burned any oil. It runs very well and 

has been very predictable. I’ve tested the 

‘mags’ every two hours in flight and have 

never had a problem. The ‘mag drop’ is 

less than 100 rpm each side.” This newfangled 

ignition system also has cured 

the engine’s propensity for fouling 

plugs, at least as it used to as an O-235. 

(Raise your hand if, as a student pilot, 

you were ever stymied by a fouled-plug 

Cessna 152.) 

Testing Ground in Use 

I dropped in on the Kitfox factory in 

early August last year, with the crew 

still digging out from their trip to 

AirVenture. Mild weather in Homedale 

made for nearly ideal test conditions. It 

was a bit surprising to see the yellow- 

and-black Super Sport with a flat 

engine installed. The last time I saw this 

airframe it had the Rotec and the ring 

cowl. The new cowling looks great and 

fits snugly. You might notice the slight 

“cheeks” molded into the top cowl 

to clear the front cylinders, but these 

may not stay. “I’m not 100% sure we 

need them,” says McBean. “Sometime 

before we release the final kit, we’ll see 

if we can get rid of them.” Otherwise, 

it’s a conventional air-cooled installation, 

with modestly sized inlets, a single 

large outlet along the lower edge of the 

firewall and a NACA-style scoop for the 

carburetor some ways below the spinner. 

For our flight, McBean was running 

a “gimme” prop. As in, gimme that 

prop standing on the wall, let’s see if it 

fits. Actually, that’s not quite it, but the 

closest to an ideal prop McBean had was 

a WhirlWind fixed-pitch, compositeblade 

beauty measuring 72 inches in 

diameter. It’s actually intended for the 

Continental O-200, but the Lycoming’s 

power and the Super Sport’s expected 

speed range would be close enough to 

the prop’s design point to perform the 

initial flights. 

To simplify development, Kitfox kept the Cub-style landing gear on the O-233 airplane; 

one advantage is that it’s slightly lighter than a normal one-piece, bent-aluminum gear. 

Shortening a cowling is harder than it 

seems, but the Kitfox crew did a masterful 

job of keeping the sleek lines and flush oil 

access door. 

Heated pitot? Not on this VFR-only Light 

Sport ship. 

Like all of the famous utility aircraft, the 

Kitfox moves the stabilizer’s leading edge 

to adjust pitch trim. It’s run through an 

electric motor that’s ever so slightly too 

fast at cruise speeds. A blip will do ya. 

This is the first effort at baffling for the 

O-233, which has a footprint almost 

exactly like the O-235. The inlet next to the 

starter gear ring provides air for the carbheat 

system. 



Other ongoing changes to the Super 

Sport are evident on N12KA. For example, 

the airplane retains the Cub-style 

steel-tube landing gear designed to look 

right with the Rotec. The criss-cross tubing 

under the belly and exposed shock 

units no doubt suck down a few miles 

per hour, but they’re likely 5 pounds 

lighter than the massive Grove-made 

aluminum gear that’s standard on the 

Series 7. This airplane also keeps the new 

smooth leading-edge treatment for the 

wings and the aforementioned fiberglass 

boot cowl—that’s the piece between the 

back of the removable engine cowling 

and the doorposts. Finally, the same 

minimalist panel is aboard, with three 

white-faced gauges in front of the pilot 

and a Garmin GPSMAP 696 taking up 

most of the center stack. (Incidentally, 

McBean is working on a more comprehensive 

engine-monitoring system to 

help flight-testing move forward.) 

Turn the Key 

Where the Rotec required a bit of 

finesse to start when cold and even the 

Rotax 912S asked for a certain process, 

the Lycoming lights off conventionally. 

The reclining seats are comfortable, while 

the ample baggage area behind can hold 

150 pounds structurally. 

Note to Rotax pilots: The red knob is called the mixture control. It adjusts the engine’s 

fuel/air ratio. Learn it, love it. 

Push the red knob in, pump the throttle, 

turn the key. It catches quickly and 

settles into a smooth, quiet idle. The 

runup is, likewise, straightforward, so 

by the time you’ve checked that the fuel 

is on (it’s either on or off), elevator trim 

is set and flaperons are deflected to the 

first notch, you’re just about ready to go. 

Because the Lycoming packs 115 

horsepower compared to the 912S’s 100, 

the initial acceleration feels sprightly 

but not night-and-day different from 

the 912S iteration. That extra power is 

partially consumed by the additional 

weight of the Lycoming, and some of 

the potential thrust is squandered by 

the slightly too-small prop. (More on 

that in a minute.) Nevertheless, you can 

count to three and then raise the tail. I 

tended to over-rotate the nose down so 

that I was unintentionally holding the 

airplane on the ground. To its credit, 

Kitfox kept the panel unchanged from this ship’s duty as the Rotec mule, but the panel 

will hold a large single-screen EFIS if you want. (A local Kitfox used in the training environment 

houses a Dynon SkyView system.) 


the Kitfox tolerated this miscue without 

complaint. 

In the climb we saw 500 fpm at 85 to 

95 mph indicated. At closer to the bestrate 

speed of 65 mph, our climb rate 

increased to 750 fpm. Notice that these 

figures are lower than what the Rotax 

posts, according to Kitfox’s data. We’d 

soon have a partial explanation. McBean 

and I leveled off at 4000 feet MSL (at 

our temperature that was 5600 feet density 

altitude), brought the throttle back 

until we saw 2800 rpm, then leaned to 

peak the rpm, which is theoretically 

the best-power mixture. By averaging 

two GPS-derived groundspeeds, 

one upwind and the other downwind, 

we witnessed a 125-mph true airspeed 

under these conditions. Pulling back to 

2600 rpm reduced our TAS to 118 mph. 

It’s worth noting that Kitfox claims 120 

mph TAS nominally for the 100-hp version. 

That small prop helped high-speed 

cruise a bit at the expense of climb performance, 

the classic set of compromises 

laid bare. 

In subsequent testing with a new 

Catto fixed-pitch prop, this one 74 

inches in diameter (plus two from the 

WhirlWind), McBean reports typical 

cruise speeds of 122 to 123 mph true. 

There may be more speed to be had with 

fine-tuning of the cooling ducts and baffling, 

and it’s likely that the Grove gear 

will give back some velocity. But until 

McBean has the full data-acquisition 

gear aboard, it’s hard to know exactly 

where the engine is running along the 

fuel-mixture curve. So many variables, 

so little time. 

The important fact is that Kitfoxes 

aren’t about blazing speed, so a few miles 

per hour here and there aren’t going to 

make or break a sale. Instead, the airplane 

is about comfortable low-speed 

handling, short takeoff and landing 

distances, and simple pleasures. In this 

sense, the Lycoming fits right in. Compared 

with the Rotax, which always 

feels busy, like it’s just finished a triple 

espresso after a plate of tiramisu, the 

Lycoming is languid, chugging along 

with little apparent effort and commendably 

little vibration. (You might 

credit the composite prop for that feat.) 

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Somewhat amazingly in an airplane 

significantly heftier than most of its 

kind—the O-233 Super Sport weighs 

868 pounds empty, approximately 70 

to 80 pounds more than one with the 

Rotax—handling is unblemished. As 

before, the full-span flaperons display 

their might to thick-handed pilots 

but settle down once you quit stirring 

the pot unnecessarily. The heavier 

Lycoming moves the Kitfox’s empty 

center of gravity forward, so that helps 

with longitudinal stability, which is very 

good. Stick forces are on the light side in 

roll, moderate in pitch and again light 

in yaw. A hint of tail waggle sneaks in 

amid low-level turbulence, but it’s just 

that…a hint. The hardest part of landing 

the Kitfox is, for me at least, pegging the 

correct pitch attitude in the roundout. 

It’s a lively airplane with a fair bit of lift 

even at low speed, so it’s easy to conclude 

a slight bounce with an amazing balloon 

ride. McBean prefers wheel landings, 

and I can see why. 

Early Days 

It’s fair to call the Lycoming O-233 

Kitfox a work in progress. Lycoming 

Access to the Kitfox’s cabin comes via twin top-hinged frames sheathed in ‘glass. 

continues to make small updates to 

the engine and systems, and McBean 

is chewing his way through prop 

choices. Until all the pieces are in 

place, it would be imprudent to drop 

performance figures into a brochure. 

Likewise, McBean is waiting until all 

the R&D is finished before finalizing 

the firewall-forward costs and specific 

components. But this much we know: 

The Lycoming O-233 lives and lives 

well. It hasn’t quite met Lycoming’s 

hopeful weight goals, but it runs like it 

should, is at its core a very well under- 

stood engine, and will likely have 

widespread support. 

For Kitfox Aircraft’s part, development 

will continue with the 233 until 

McBean is convinced it’s as refined 

as it can be. And then…who knows? I 

thought I spied a tractor-trailer from 

Acme Aircraft Engines pulling up to the 

loading dock, but that could have been 

my imagination. J 

For more information, call 208/337-5111 

or visit www.kitfoxaircraft.com. Find a 

direct link at www.kitplanes.com.

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