Affordable Acro

If loops and rolls appeal, we see six practical choices. Valuewise, the Citabria and Decathlon are hard to beat.

So youve had enough of stultifying straight-and-level cross countries and $100 hamburgers and what common sense you had before getting into flying has finally dissolved. What you really want is an aerobatic airplane, something you can wring out on a Saturday afternoon and maybe even use for some novice competition flying.

Where to start? Interestingly, the selection of aerobatic airplanes is quite large. You can buy a new production model capable of a modest Sportsman sequence or a Herculean off-the-shelf Unlimited competitor. Money, of course, is the only object.

In this article, we’ll examine used production aircraft, with an emphasis on the low end of the price scale. In a later article, we’ll look at new production aircraft. We havent considered every possibility here, just the major players and some honorable mentions. But first, a word on legalities and common sense. Every year, a certain number pilots-almost invariably males-kill themselves by botching aerobatic maneuvers in a normal category airplane. While there is a Darwinian attractiveness to ridding aviation of pilots with the judgment level of a six year old, these guys often take innocent passengers with them after uttering that fatal phrase, Yall watch this.

Yes, its possible to do many aerobatic maneuvers in a normal category airplane. But there’s little margin for error. If you flinch, there goes the velvet. Normal category airplanes have lethargic roll rates compared to aerobats and that lack of roll can get you into serious trouble if the nose drops in a roll. So, if youre going to fly aerobatics, do it in an airplane designed for the task.

Wishes and Desires
First, budget. And will aerobatics be an all-consuming passion? Will you want to compete and possibly perform in local airshows? Or does the prospect of pirouetting around on the weekend in an airplane that can double as a cruiser appeal?

For us mortals, a used production airplane is the most realistic approach to ownership of an acro mount. We see six practical choices: The Cessna Aerobat series, the Citabria and Decathlon series, the CAP 10, the Pitts and T-34 Mentor. In the honorable mention category are the Stearman, Waco UPF-7 and Great Lakes classic biplanes.

Cessna Aerobat
In 1970, Cessna beefed up the structure of its popular 150 trainer with additional stringers, nearly doubling the number of rivets and using heavier wing struts to strengthen an already sturdy airframe. Just a couple of 150/152s have broken up in flight and we know of no Aerobat break ups. As an aerobatic airplane, the Aerobat never got much respect because it wasnt especially macho and it had a nosewheel. Get over that, however, and its adequate for basic aerobatics. Its approved for all positive-G acro work, which eliminates the slow roll and hammerhead, due to lack of oil pressure to the engine when there’s no positive G loading. Anyone screwy enough to try outside or negative-G maneuvers soon discovers that doing so blows oil over the airframe, leading to a tedious clean-up job.

Few pilots have trouble transitioning into tandem seating aircraft from the Aerobat. The Aerobats obvious weakness is lack of power. It loses altitude diving for entry speeds and clawing back up for the next try is leisurely, to say the least.

In a normal loop, the Aerobat gives up about 300 feet for the entry and can come out at the bottom at the same altitude at which you pulled up, but you’ll be about 20 knots slower. Thats fine if you wish to go directly into a rolling maneuver. As a result, energy management is something Aerobat pilots learn early.

Rolling maneuvers in an Aerobat require thought. As with all positive-G rolls, the nose must be pitched up at least 30 degrees for an aileron roll. The wheel is then turned upside down, which presents a coordination challenge while you fine-tune pitch. Because control forces are light, the task isn’t difficult to sort out.

Anyone who learns to do clean aerobatics in an Aerobat will have little trouble stepping into an airplane with a stick. An Aerobat teaches good habits simply because theyre essential to complete maneuvers with any grace.

Snaps, Spins
Where the Aerobat shines is in snap rolls and spins. Due to the sweep of the wing at the strut attach point, the effect of yawing the airplane as its stalled is magnified slightly. The airplane enters snaps and spins from accelerated stalls more cleanly than any of the production aerobatic airplanes, but it requires full rudder to do so. It recovers from snaps and spins more crisply than its competition, although simply relaxing the rudder input breaks the spin easily.

Prices, according to Vref, are about $18,200 retail for the 1970 Cessna 150 Aerobat and escalate to $21,900 for the 1977 model. The 150 Aerobat seems to command about $500 more on the retail market over the non-aerobatic 150. For the 152 Aerobat, typical retail is $28,500 for the 1978 edition and up to $35,500 for the last model year, the 1985. Thats about a $3000 premium over the non-aerobatic version.

There are several models of the Citabria, an outgrowth of the Aeronca C-3, K and Champion line. In general, the lower power models have 100 HP Continental or 115 or 118 HP Lycoming engines and a choice of flapped or no flap wings, while the bigger engine versions have either 150 or 160 HP.

All had fixed pitch propellers. The 7KCAB has no flaps, 150 horsepower and was the only version with an inverted fuel and oil system. These are step ups from the Cessna Aerobat in capability, even though they were not originally designed as purpose-built aerobatic machines. The Citabrias do require less pilot effort to perform the maneuvers cleanly. As with the Aerobat, the lower-powered versions take their time getting to altitude and sacrifice speed and altitude in each maneuver. The Citabria has a stick and a tailwheel, both aesthetic essentials in the world of aerobatics.

All are soloed from the front seat, which is a huge plus for visibility. Unfortunately, the Citabria doesnt have well-harmonized controls, most noticeable of which are the far too heavy ailerons. Spades are worth the price on a used airplane and worth retrofitting if not already installed.

The 150 HP version, the 7KCAB, is a very good combination of capable aerobatic, cross country and knock around airplane. It has the power to reach altitude briskly and if power and speed are managed appropriately, you’ll lose a minimum of altitude building speed for a loop with an exit at the same altitude and speed as the pull up.

The Citabia cruises at an honest 110 knots on about 7 gallons per hour and gets into and out of small strips nicely. Flying aerobatics, then slipping down final over the trees into a grass strip on a summer evening in these airplanes is the sort of thing that inspires poets.

The Citabria and Decathlon share one highly desirable trait: Theyre among the most docile of tailwheel airplanes on the ground. Visibility from the front seat is nearly equal to a tricycle airplane and they track straight ahead when taxiing. If the one youre considering doesnt, somethings wrong. Weve flown more than one Citabria and Decathlon which tracked significantly sideways, probably due to landing damage.

Either airplane does excellent wheel or full-stall landings and both are good choices for a tailwheel airplane checkout. For the person seeking an all around airplane, its difficult to go wrong with a Citabria or Decathlon.

Watch the Wood
The wood wing spar Citabrias and Decathlons are the subject of a number of service letters and potential ADs regarding inspection for compression cracking on the top of the spars as we’ll as longitudinal cracks through bolt holes, spacer holes or nail holes as we’ll as butt ends of the front and rear spars.

The service letters are 406 and 417, Revision B. As this report is being prepared, ADs calling for repetitive wood spar inspections and installation of inspection holes in the wing skins appear likely. The controlling variable on wing spar cracks seems to be damage history. Airplanes which have been on their backs or had wingtip impacts should be suspect. Look the logs over carefully, even though this damage isn’t always logged.

Worst case, failing to check for damage may cost you a fresh set of wings for your newly acquired airplane. Check the battery box area, too. The battery gets thrown around and sometimes acid gets where it shouldnt. Late 60s to last 70s 7K-CABs sell for between $29,000 and $37,000.

The Decathlon developed from the 150 HP 7KCAB Citabria, keeping the same power with an inverted fuel and oil system, while adding a constant speed propeller, symmetrical airfoil and a shorter wingspan.

The result was a very good, intermediate-level acro machine. With plus 6 and minus 5 G load redlines, it will do all positive and negative acro reasonably well. Some owners swear the airplane is slightly faster inverted than right side up due to the angle of incidence of the wing. As with the Citabria, the Decathlons ailerons are too heavy for its elevator and rudder; spades are essential.

For serious aerobatic pilots, the Decathlon is a decent mount, short of the leap to a Pitts, yet it had one shortcoming: lack of vertical ability. The solution was the Super Decathlon, a 180 HP version which addresses many of the complaints of those who wanted more from the 150 HP version. However, even the Super Decathlon wont do much more than a half upward roll on a vertical line.

All of the Citabrias and Decathlons must be loaded carefully. Two adults with parachutes often means that no more than about half fuel can be carried. If youre looking for a used Citabria or Decathlon, recognize that in the real world, these airplanes have been flown over gross so inspect them as if they have been overstressed. Look over the wings and tail structure carefully.

Many Decathlons have been used for aerobatic training and its not unusual for hamhanded aerobatic students to make mistakes and take the airplanes through redline on speed or over the maximum G limit before an instructor can intervene. Pre-purchase inspection on these airplanes, particularly those with wooden spars, must be done with great care. To be blunt, its not a question of whether a used aerobatic airplane has been over stressed, but how badly and what damage has resulted. Watch for it on the pre-buy.

Decathlons are valued at $33,500 for early 1970s models up to $62,000 for early 1980s used airplanes.

T-34 Mentor
Beech built hundreds of T-34A and B primary trainers for the Navy and Air Force from 1949 through 1957. They were so successful that they were followed in the late 1970s with a C -model powered by a turboprop engine. Military pilots never seemed to call them the Mentor. They were known affectionately to the Navy types as the Weeny, with the C being the Whisper Weeny. Very few turboprop versions are in private hands, despite Beech selling them directly to the public for a time, so that type will not be discussed.

The T-34 was essentially a beefed up, conventional-tailed version of the Bonanza but two place, with tandem seating, a canopy and a 225 HP Continental. Control sticks took the place of wheels. The result is a remarkably easy to fly machine.

Controls forces are moderate, lighter in roll than the Decathlon, but heavier in pitch and not as quick in yaw. It takes enough pull to load the airplane in pitch that inadvertent over-controlling would require a ham-fist who truly drives an airplane rather than flying it. The unanimous description among all who have flown the airplane is smooth, but the word light is rarely used when describing the controls.

The Mentor does primary aerobatics without much strain, although the T-34 is a large enough airplane that vertical ability is limited. Visibility from the canopy in the air and on the ground is outstanding. Both occupants have the choice of flying with their respective portion of the sliding canopy open.

With 225 horsepower in a heavy airplane, advance planning and energy management just isn’t enough to hold altitude during a series of maneuvers. As a result, many T-34s have been modified with a Continental IO-520, or IO-550, which improves all areas of performance.

The Mentor is almost free of bad habits. Cruise speed is about 140 knots, with a range of approximately 460 miles from 50 gallons of fuel for the stock, 225 HP airplane. Many T-34s are set up for instrument flight and the military-style gyros can be caged to reduce damage during aerobatics, a real plus in an airplane that will do double duty. The T-34 is a complex airplane with tricycle gear, flaps and a constant speed prop, so pre-purchase inspection should take that into account. A good inspection will take most of a day. Many T-34s had a number of magnesium fittings, most of which have been done in by corrosion over the years. Make sure those have been replaced.

Some of the airplanes have had extensive rebuilds, the recency and quality of the rebuild, along with any engine conversion, determines the price. Age is not important in the price, which leads us to the airplanes chief downside: Being a warbird, prices are inflated. Even Mentors in poor condition might fetch $115,000, according to Vref. Good restorations have commanded prices in the $250,000 to $300,000 range.

CAP 10
The CAP 10 has been around for we’ll over 20 years, pleasing pilots with its agility and ruggedness. In a world of angular aerobatic airplanes, its curving lines are a surprise, giving it a deceptive appearance of delicacy that belies its performance.

Its an outstanding all-around airplane, from the perspective of a tailwheel transition aircraft to a responsive aerobatic trainer, reasonable cross country machine and good competition mount through the Intermediate level.

Why, then, hasnt the Cap 10 flooded the market in the U.S? We see three reasons: Cost, xenophobia and lack of marketing. While it has the same power as the Super Decathlon, the CAP 10 has better control harmony and responsiveness and is slightly more capable in vertical maneuvers. Yet Americans are somewhat suspicious of foreign types and the French have done nothing to dispel that through friendly marketing.

Aerobatic experts who have flown the CAP 10 give it high marks. It has a more than satisfactory roll rate and is clean enough with short wings that it has decent vertical ability, thanks in part to the 180 HP AEIO-360 Lycoming. The bubble canopy gives superb visibility in the air and the seating position makes for good visibility on the ground. Its ground handling is straightforward, but quick, so it requires attention. Its aerobatic certification is for plus 6 and minus 4.5 Gs, almost the same as the Decathlon.

Cruising speed at 75 percent power is about 135 knots. As with several aircraft, the allowable gross weight is higher for normal flight than for aerobatics; make sure the airplane you have in mind will carry decent fuel with two parachuted pilots aboard.

CAP 10s are wooden airplanes and all of the cautions about examination of components on a wooden airplane should be considered in a pre-purchase inspection. There are only about 35 CAP 10s in the U.S. which is good and bad. It means that not a lot come up for sale at any given time, but, as the importer for the airplanes in the U.S. is Mudry Aviation, Ltd at Flagler County Airport, Bunnell, Florida, (904-437-9700) they know many of the airplanes and keep track of them.

As a result, Mudry does a lot of the service of CAP 10s and is considered the source when it comes to doing a pre-purchase inspection. Prices on used CAP 10s are about $80,000 for one in good flyable shape.

The S2-A and S2-B versions of the Pitts were in production for a number of years. The S-2B can still be specially ordered from Aviat. These aerial hot rods carry two pilots and have, respectively a 200 or 260 HP Lycoming engine with full inverted system.

A Pitts is about as small a biplane as can be imagined to carry two people, fuel and a large engine. Both are exceedingly clean and, to put it mildly, go like crazy. Its hard to believe that a few years ago these were considered near the best in world competition but are now being used for primary training for those who seek to move up to the Extra, CAP 232 or Sukhoi.

The controls are we’ll harmonized. For one who came up in acro flying an Aerobat or Citabria, the overwhelming feeling is its only necessary to think about a maneuver to fly it. Most of those pilots over control the Pitts the first time out. For one accustomed to running out of speed almost instantaneously in the vertical in a Citabria, the Pitts is a revelation.

Shortcomings: Visibility on landing is awful and the airplane is just plain hard to land. Its essential to get a good checkout before you fly the airplane home or you run a significant risk of tearing it up on your first couple of landings.

In addition to the standard aerobatic pre-purchase checklist, look for slop in the control system. It often just requires an adjustment but bearings can be worn out. Any Pitts flown regularly for aerobatics should be inspected frequently. Make sure the inspection holes have been cut in the underside of the wings, an indication that the owner has been looking at the structure.

Once the wings are bolted together, the upper and lower wings form a rigid unit so an impact to the lower wing may result in damage to the upper. Its essential to inspect each wing. Look to see if the spinner and nose bowl line up. If not, the bushings on the engine mounts are worn and are allowing the engine to sag. While this is initially cosmetic, it can result in the alternator being pushed into the nose bowl and the exhaust hitting the front of the fire wall as we’ll as crushing the air box. Prices for the A and B run from $40,000 to more than $100,000 depending on condition, age and equipment.

Classic Biplanes
No survey of acro airplanes would be complete without at least passing nods to the Stearman, Waco and Great Lakes biplanes. The Boeing Stearman is probably the most numerous, having been built in the thousands at a primary trainer.

Most had a 220 HP Lycoming or Continental radial but conversions are available for 300 and 450 HP. A Stearman is remarkably easy to fly, although it has lousy visibility once the nose comes up and with its narrow gear, it can be a handful on the ground. For aerobatics, its somewhat ponderous but the ball-bearing feel of the controls makes any perceived shortcomings forgivable. A ratty Stearman can be had for $30,000, while a superb restoration with a 300 or 450 HP engine will command more than $100,000.

In the mid-1970s the venerable Great Lakes design was resurrected and put into production. Its a tandem, two-seat, biplane with a 200 HP Lycoming IO-360 (although some have 180 HP) and an inverted fuel and oil system. The Lakes is, simply put, hugely fun to fly. Its larger than the Pitts and more draggy so vertical maneuvers are limited. Inverted work is as good as the Decathlon and snap rolls are great fun. With the swept upper wing it unhooks and rehooks cleanly. A pre-purchase should concentrate on corrosion, engine condition, mounts and propeller condition.

Last, the Waco UPF-7, one of the first of the big biplanes to be just plain easy and fun to fly. The controls were harmonized well, the gear stance was wide enough and the vertical tail big enough to allow good handling in strong cross winds. The UPF-7 was purchased in quantity as a trainer by the Army in World War II and has proved popular as a civilian airplane. The front cockpit is capable of carrying two people. As with most airplanes of its era, it is soloed from the rear seat. It has the usual crummy visibility on the ground but isn’t too bad in flight despite wings seeming to be everywhere you look.

This airplane is one of the best handling and flying of the World War II era biplanes, in our view. Its slightly smaller than the Stearman, has lighter controls and is more responsive or less ponderous, depending on your point of view.

As with the Stearman, most Wacos have been rebuilt or restored at least once. Make certain you have a pre-purchase inspection performed by a mechanic who knows the type well. Lack of support from the Antique Aircraft Association is of concern , so the prospective buyer will need to build a network of knowledgeable people before diving into ownership.

Final Thoughts
In buying an acro airplane, keep this in mind: With the exception of the Cessna Aerobat and T-34, all are ragwings and should thus be hangared. Storing them outside even in mild climates is a bad idea. Factor that into your buying decision.

All things considered, unless youre set on a classic biplane or want to break into the warbird community with a T-34, the Citabrias and Decathlons are hard to beat, valuewise. They have both sticks and tailwheels and although fabric covered, theyre modern airplanes we’ll supported by a going company, American Champion Aircraft in Rochester, Wisconsin.

For a neophyte aerobatic pilot, we cant see how youd go wrong with one, assuming it passes a careful pre-buy inspection.

Also With This Article
Click here to view “Acro Pre-Buys: Thumping the Fabric Won’t Do It.”

-by Rick Durden
Rick Durden is an aviation attorney and an aerobatic instructor.