You’re looking for utility—a cruise speed across the ground in triple digits, even with some headwind, a cabin large enough to take friends or family and your, um, stuff and you want to be able to get away from it all at remote airstrips.
Bottom line, you’ve decided that you want a four-place STOL flying machine because just two seats doesn’t cut it—and STOL two-placers are often as expensive as four-place birds—and a six-place airplane is a luxury outside of your budget.
What’s STOL?
Let’s start by discussing what it is that you want to buy. A STOL airplane is defined by the Department of Defense as capable of taking off on a standard day at sea level and clearing a 50-foot obstacle in a total distance of 1500 feet. It has to be able to land over that same obstacle and come to a full stop in 1500 as well.
That’s short. That’s no kidding around short. Think about the last time you landed on a 2000-foot runway with no obstructions. How’d you do? Think about the STOL competitions you watch on the internet—the airplanes land and stop quickly, but you almost never get to see them clear a 50-foot obstacle first. We think that would make for a real competition.
We think that there are a few four-place singles that can meet the official STOL definition out of the box, some that can do so with appropriate mods and more that—with or without mods—have enough utility to safely get in and out of short backcountry strips even though they cannot meet the 1500 foot with obstruction criteria.
If you’re in the market for four-place STOL, we think the first step is to take a few minutes to decide what you really want to do with the airplane. This is the time to recognize that macho costs a lot of money and those big tires that look so cool when you’re sitting on the ramp may not be what you need for the flying you plan to do.
Introspection
Also consider if you’re willing to take the dual needed to get your skills up to the precision demands of STOL—and recurrent training to keep them there. Precision flying skills atrophy quickly.
Take some time to think about what you want to carry. For STOL operations weight is everything. We think that the ability to carry what you desire while staying at least 100 pounds below gross will pay big dividends. After all, for every increase of 10 percent in weight, takeoff and landing distances go up by 20 percent. You don’t want to have second thoughts about your airplane selection shortly after liftoff as the trees ahead get taller rather than smaller.
That’s a big reason that we like four-place airplanes for STOL and backcountry operation. We consider them to really be two- or three-place, so that we can carry a friend or two and gear and have that warm fuzzy feeling of being 150 pounds below gross when the temperature goes up, the grass on the runway is long and those trees look to be closer to 100 feet tall than 50.
In researching this article we interviewed and flew with a number of experienced STOL pilots and CFIs and asked them what they thought were attributes of airplanes that make them the sort of STOL machines that a pilot needs when planning to take them in and out of tight strips.
Attributes
- The unanimous first choice was power. When things go south, horsepower may—just may—allow you to extract yourself from a jam resulting from your error in judgment or technique.
- Big, high-drag flaps that allow that good climbing airplane to come down like a dropped sewer cover.
- Tough landing gear that will take the punishment dealt out by rough fields and firm landings and that has brake lines routed to protect them.
- Excellent low-speed handling—which includes good control responsiveness as speed bleeds off on rollout. Remember, the majority of short-field accidents involve loss of control during rollout.
- Landing gear geometry that won’t put the airplane on its nose with heavy braking.
- Easy-to-use flap control.
- Ability to slip steeply with no oddball handling when entering or recovering from a slip.
- Good prop clearance.
- Good visibility over the nose on approach and in the flare.
- Easy-to-use, intuitive, fast-acting trim.
- Good stability on approach—it should be easy to nail your approach speed within 2 knots.
- Good visibility when maneuvering, especially in a steep turn and when looking down and aft, as you do more often than you realize in the backcountry.
- Good cruise speed so that things don’t get dodgy when you have to carry reduced fuel for weight and you hit a headwind enroute to your fuel stop.
- A high wing so that the general detritus on less-than-great fields doesn’t tear off a flap or poke a hole in a wing leading edge.
- Tires large enough to spread weight around on soft, rough or rutted surfaces and provide adequate prop clearance.
- Beefed-up nosegear leg to increase prop clearance and absorb shocks on rough/rutted fields.
Which Gear?
This fight is too old. Tailwheel airplanes are more macho and generally look cooler than nosewheel machines but we hope that you are able to look past appearances and evaluate your skill and what is right for you.
The hard and fast reality is that if you buy a tailwheel STOL airplane, you are twice as likely to wreck it on landing than if you go nosewheel.
Yeah, yeah, yeah, we know that mantra, tailwheel pilots are better stick and rudder pilots than nosewheel pilots. We happen to think it’s true. After all, we’ve been giving tailwheel instruction for 50 years and we’ve seen how much pilots improve their skills when they get tailwheel checkouts. However, even with the training and greater stick and rudder skills, pilots flying tailwheel airplanes still wreck them at twice the rate they do on landing than when flying nosewheel airplanes.
When prop clearance really matters, tailwheel is generally better. However, other than that, it’s a myth that tailwheel airplanes are somehow magically better for landing on unpaved runways because those runways vary in condition so much. We’ve broken a tailwheel off on a rutted field because there was weight on the tailwheel during rollout. A nosewheel airplane would have had no problem because holding the yoke aft during rollout meant it would have had less weight on it and its diameter was enough to span the rut.
For true STOL takeoff performance, a nosewheel airplane has a slight advantage—it starts its takeoff roll level.
On rollout, the ability to stand hard on the brakes without nosing over gives a nosewheel an advantage. We’ve read too many accident reports of tailwheel airplanes on their back at the end of a landing attempt.
By the same token, we are aware that pilots with the advanced skills required can make incredibly short landings in tailwheel airplanes by spiking the airplane onto the mains and holding it there with heavy braking and careful manipulation of the elevator to keep maximum weight on the main gear.
We have ridden through some landings in Cessna 185s and a T-50 Bobcat in which the pilot used that technique and we thought he’d thrown out an anchor.
We think that the decision between nosewheel and tailwheel is one you make based on a rational evaluation of your age, level of experience, how often you fly to maintain a skill level and what insurance is available. We’ve seen way too many guys, yes guys, buy a tailwheel airplane for a second airplane because of the cool factor and then either wreck it on landing or sell it within a year because it scared them.
Blunt enough? All we can say is that it’s essential to shut off your need for macho when selecting a STOL airplane.
MODS for STOL
When the hype ends, STOL is all about power and a low stall speed. There’s a good chance that your four-place Cessna can be modified to become a decent STOL airplane.
Reducing stall speed means either VGs, which work their stall-speed reducing magic for surprisingly small sums (as aviation money goes), a short install time and almost no weight increase, or a STOL kit.
VGs have been around since the 1930s and we like them because they go beyond reducing stall speed to improving low-speed handling and, when installed on the vertical stabilizer, improve rudder effectiveness and ability to handle crosswinds. Some installations also put VGs forward of the underside of the elevator to improve its effectiveness when coming into the flare at low speed. Owners report stall speed reductions of 4 to 8 knots. We last reviewed VGs in our March 2019 issue. The big dog in the VG world is Microaerodynamics (www.microaero.com) although there are others.
STOL kits install a cuff over the wing leading edge to change the shape, reducing stall speed. They also reduce cruise speed. Some add a stall fence on top of the wing to delay the propagation of a stall outboard and some droop the ailerons to improve their effectiveness at low speed. They reduce stall speeds by 4 to 8 knots.
For the greatest reduction in stall speed, add VGs to a STOL kit. You won’t get the advertised speed reduction of the STOL kit plus the VGs; however, you will get more than either just VGs or the STOL kit. We provided the details on stall speed reduction when adding VGs to a STOL kit on a Cessna 182J in the March 2019 issue. Our tests showed a 16-MPH reduction in stall speed.
Power
For more power to get you off the ground and climbing over the obstacle, there are a number of mods to drop in larger engines. We explored the options in detail in our October 2022 issue.
For less money than a new engine, we like tuned exhausts and electronic ignition, both of which give measurable improvements in rate of climb.
Tuning your engine’s exhaust system to make it more efficient by reducing back pressure on the engine and increasing power output is a technique long used in the racing world. Power Flow Systems (www.powerflowsystems.com) offers tuned exhaust systems for virtually all single-engine piston airplanes.
We’ve flown airplanes with the mod and have observed measurable increases in rate of climb as we’ll as cruising speeds.
Electronic ignition systems increase engine power output by adjusting ignition timing and boosting spark output. Installation involves replacing one magneto with an electronic unit. The one provider we’ve found that is sophisticated enough to notably improve power output, rate of climb and service ceiling is Electroair (www.electroair.net).
In a before-and-after comparison of performance in a 180-HP American Champion Scout, we found that with the Electroair electronic ignition, the new rate of climb was nearly as good as the 210-HP Scout Denali.
What’s Out There?
In our opinion, the best of the best four-place STOL airplane out there is the King Katmai conversion of the Cessna 182 by Peterson’s Performance Plus (www.katmai-kenai.com). With a 300-HP IO-550 up front, flanked by the wings of a canard, the full conversion boasts a 31-knot stall speed and a 1500 FPM rate of climb. We covered the beast in our January 2013 issue.
We especially like that with the lifting surface canard, the aircraft flies in a nearly level attitude near the stall, making for excellent visibility going in and out of short fields.
Peterson’s Performance Plus also offers the Kenai, which is similar to the King Katmai but with a shorter wing, giving a higher cruise speed and a 3-knot higher stall speed.
Maule
The top of the purpose-built four-place STOL line is clearly, in our opinion, the big-engine, four-place Maules (www.mauleairinc.com). In production since 1960, the wide-ranging Maule series include machines with engines from 145 to 260 HP. In our opinion, the over-200-HP ones meet—or at least come close to meeting—the DOD definition of STOL.
If it’s possible to land an airplane on something, a Maule has probably landed there. As one of our friends put it after a flight in a Maule M-5 with large-diameter Bushwheel tires, “That field was so rocky that I wouldn’t drive my pickup over it—the Maule handled it smoothly.”
Most Maules come with a tailwheel, but there are some nosewheel versions. We covered the tailwheel Maule line in our Used Aircraft Guide in the November 2020 issue.
Over the years we’ve flown most of the Maule series and have found that for the over-200 HP birds, gross weight takeoff distance on a standard day is on the order of 500 feet with a climb rate of at least 1000 FPM.
On the tailwheel ground handling spectrum, Maules rest on the good end. Handling at all speeds is generally good. There is an aileron-rudder interconnect that takes some getting used to at first.
We particularly like that on newer model Maules, the entire right side of the cabin can be opened up for easy loading and unloading.
Cessna
The Cessna 170, 172, 175, 180, 182 and 185 (many 185s have six seats but the cabin is about the same size as a 180) may be considered serious STOL with appropriate mods. That means, primarily, more power, along with VGs and/or STOL kits. For the 170, 172 and 175, we think that means at least 180 HP up front plus Power Flow exhaust and/or Electroair electronic ignition. However, before making all of the mods, we think that it would be more economical to get into a big-engine Maule. We think that a 172XP with a tuned exhaust, electronic ignition and STOL kit/VGs could make the cut.
The 180 and 182 with stall-speed reducing mods and a power bump cross the line into STOLland, in our opinion. We just wish that Cessna would have widened the cabin of the 180/185 when it did so on the 182. All the 185 needs in the way of mods, in our opinion, is a STOL kit and/or VGs.
Piper
The Piper Pacer and Tri-pacer are regularly used in the backcountry, although even with 180 HP up front and stall speed reducing mods, we don’t quite see them having the rate of climb needed to meet the STOL requirement at gross weight. Nevertheless, they can often be had for an attractive price and their cruise speed makes them quite suitable for most backcountry operations.
Aeronca
Finally, we have a soft spot for the Aeronca Sedan. There were more than 500 of the four-place Aeroncas built and, because of their excellent low-speed handling—even though the wing has no flaps—a lot migrated to the Alaska and Canada bush.
Operators removed the back seats and did reasonably we’ll with the original 145-HP engines, but with a big engine conversion and other mods, the steel-tube-and-fabric Sedan can approach STOL performance.
Conclusion
If you’re in the market for STOL, and are willing to ramp up your skills, there are a lot of four-place machines on the market and lots of mods to increase their capabilities. If you have the budget, the King Katmai does the most, but for those on a budget, we think that Maules offer the most bang for the buck overall.
Sliding into the command seat of a STOL aircraft doesn’t make a pilot capable of wringing out all of the performance built into it any more than expensive ski clothes turn someone into a giant slalom winner. On approach to a short-field landing, a STOL machine is operating deep in the region of reverse command and in such a high drag regime that failure to fully understand the aircraft’s low energy condition and/or being a bit sloppy in airspeed control can result in a sink rate that can’t be stopped before hitting the ground.
At the other end of the short-field energy spectrum, sloppy airspeed control can mean so much energy that a pilot facing a strip from which a go-around is impossible can’t get down and stopped in the space available.
In our opinion, to take full advantage of the short-field capabilities of a STOL aircraft, a pilot needs to spend some quality time taking dual from a CFI who has STOL and, preferably, backcounty experience in the particular type of airplane.
We spoke with backcountry instructors about what they teach pilots checking out in a STOL airplane. Their answers were pretty consistent.
- Energy management was emphasized heavily, along with the need to be able to hold airspeed precisely.
- The pilot will need to get comfortable flying the airplane with full flaps at a few knots above the power-off stall speed. Naturally, that involves finding out what the power-off stall speed is, so doing a number of power-off stalls with full flaps in level flight and banks up to about 30 degrees and writing down the indicated airspeed at the break. For example, we found that the power-off stall speed for the 182J with a STOL kit and VGs that we reviewed in the March 2019 issue was 39 MPH. We found that we could comfortably fly it level with full flaps at 45 MPH.
- As a prerequisite for training the pilot should be able to maintain a desired airspeed within 2 knots with full flaps both in level flight and on approach.
- Training the pilot to descend as steeply as possible over an obstruction, power-off or with some power, at the correct approach speed for the airplane and how and when to add the right amount of power to break the descent and flare, and then get rid of the power to spike the airplane onto the ground in minimal distance. For landing over an obstacle, CFIs told us that they started the checkout by flying power-off at 1.3 Vso for the unmodified airplane and making sure the pilot could flare and land without adding power. They then progressively slowed the approach speed toward 1.3 Vso for the modified airplane, getting the pilot used to adding appropriate power to break the descent and then close the throttle at the right time.
- All landings during training are “spot” landings, targeting touchdown at a particular point with the airplane under full control.
- When landing on a runway with no obstruction, the pilot should be able to flare prior to getting to the runway so that the airplane touches down just after crossing the threshold.
- How to get maximum brake effectiveness.
- Training should include in-depth discussions of the painful effects of density altitude on performance, including post-takeoff climb performance in feet per mile. The advanced aircraft performance training should be designed to instill in the pilot an understanding of what the airplane will and won’t do and how to accurately calculate a realistic required runway length for the density altitude, winds, runway condition and aircraft weight. The training should also include discussion of crashworthiness, use of occupant restraint systems and survival equipment.
We’ve been watching a number of the STOL competitions broadcast on the internet and note that the popular STOL Drag (www.stoldrag.com) competitions offer STOL training for pilots in association with their events. The two-day course focuses on spot landing, power and energy management and directional and altitude control. The course is required to compete in STOL Drag events although we think that it would prove valuable for any pilot who flies a STOL aircraft, regardless of a desire to compete in sanctioned events.
All of the mountain and backcountry flying courses we’ve reviewed over the years incorporate STOL operations into the course. We recommend such courses highly.
We also recommend mountain operations material on the websites of AOPA (www.aopa.org), the FAA (www.faa.gov), the Backcountry Pilot (www.backcountrypilot.org), the Recreational Aviation Foundation (www.theraf.org), Idaho Aviation Association (www.idahoaviation.com) and the Colorado Pilots Association (www.coloradopilots.org).
—Rick Durden
