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Flight Reports

November 2016 Issue




Miniature Yankee

The BD-17L has much in common with the original BD-1.

A long time ago, nearly 50 years as close as I can figure, Jim Bede Sr. was a young aeronautical engineer who conceived a simple aircraft for the masses. The airplane, known as the BD-1, required few unique parts to assemble, had honest handling qualities, and could be mass produced in large numbers at low prices. As some may remember, it was the eventual prototype for the certified American Yankee, later to become the Grumman Yankee, Trainer, and TR-2. The design grew into a four-place version, the Grumman Traveler, which then morphed into the Cheetah and Tiger, all of which have a fiercely loyal following of pilots and owners to this day.

Simplicity has always been a mark of Jim Bede's design work. Wingskins are simply folded rectangular aluminum sheets.

That one design prototype produced many successors and thousands of airplanes—yet utter simplicity had still not been achieved. Bede still searched for an airplane that anyone could own—and build—and that required little to no unusual fabrication skills.

The aluminum honeycomb construction of the fuselage is apparent at the canopy rails and behind the seat. This has proven to be very strong in previous Bede designs.

That search continued for decades, through many models and configurations. In his quest, Bede employed many young engineers, fabricators, and pilots who went on to do stellar things of their own in aviation. Perhaps you've heard of Burt Rutan? He's a Bede alumni. Airshow pilots Corky Fornoff and Bobby Bishop? More associates of Bede in his Newton, Kansas, days.

The BD-1 was followed by an endurance record-setter, a one-off airplane designated the BD-2. The -4 followed, then the famous flying egg, the BD-5. Many more digits joined the ranks of his design catalog until he reached the high teens, and the BD-17 was born, a return to the roots of simplicity, compact design, and easy construction. This may well be the airplane that many Yankee pilots dreamed of when looking for a simple airplane with enough zest to satisfy, but without the burden of an extra seat. After all, fighter pilots usually fly alone, don't they?

The swing-back canopy on the BD-17L shows the heritage of the design, as it looks very similar to the canopy on the BD-5. The long wings allow the airplane to stall slow enough to qualify as an LSA.

The BD-17 strikes one very much to be a flying jet ski. Yes, there are many larger boats available to the fisherman or pleasure-boater, but if you just want to go fast and have fun on the water, it is hard to beat a single-seat jet ski. The BD-17 is much the same, a single-seat airplane that you strap on and—burning just a couple of gallons an hour—go and explore the neighborhood from the air.

Always Evolving

Then along came the Light Sport rules. The lure of an airplane that you could build cheaply, had benign stall speeds, and that could be flown without a medical was more than Bede could resist. In fact, it had been his dream for much of his life. The -17 looked like his ticket into the LSA world, but it needed a few modifications first.

The BD-17 became the BD-17L when the LSA rules were written, the "L" designating the long wing used to reduce the stall speed to that required to meet the new regulations. The original -17 used a shorter wing, which had a higher stall—and therefore—higher takeoff and landing speeds. Of course, with increased span comes reduced roll rates, but that was the compromise made to fit into the new LSA category.

The factory jig for the BD-17L fuselage provides a clamping force to hold the few elements together as the adhesive sets. This assures a straight and true assembly.

Traditional Bede Construction

The BD-17 is pure Bede when it comes to construction. The fuselage "canoe" is made up of aluminum honeycomb panels for the bottom and sides. These are bonded together, with the corners reinforced by aluminum angles. The bonding in the early Bedes required baking in order to cure; the new process uses a two-part adhesive that is cured at room temperature, making it practical for the homebuilder. The turtledeck of the fuselage is a curved sheet of aluminum with bulkheads added where required.

The jig for BD-17L tail surfaces clamps the skin and ribs together as the adhesive cures.

The wings use the trademark tubular spar of the Bede designs, along with ribs cut from the same honeycomb used for the fuselage. The ribs are cut by Bede using a router—lasers or water jets won't work because lasers melt the adhesive making up the honeycomb, and water jets tear the material to shreds. The ribs have a main hole in the center for the spar, so the ribs are threaded on, then spaced out to the required distance, squared up and glued in place. The trailing edge aligns the ribs and is fastened with adhesive and riveted clips. All adhesive in the wings is polysulfide sealant, making a natural fuel tank of the wing itself. This is unlike the earlier Yankee, which used the hollow tubular spar, limiting the total amount of fuel the plane could carry. Wiring and plumbing is added once the ribs are bonded to the spar, then the skins are wrapped around the substructure and adhered the same way—with polysulfide sealant.

Wing ribs for all the available Bede designs are cut from aluminum honeycomb sheet.

Modern two-part sealants/adhesives are used to create the various structures that form the BD-17L. This makes homebuilding possible. Earlier Bede bonded structures took factory equipment to cure the adhesives properly.

Bede personnel use custom-made jigs to align the ribs and spars, and can build a wing fairly quickly. The limiting factor is the time it takes the adhesive/sealant to cure. When demonstrating the process, they could physically put the parts in place in a very short time, but the overall wing-bonding process takes about two weeks for a set. If a buyer chooses the quickbuild option, Bede will assemble the wings and fuselage canoe on their jigs in Florida and ship it out that way. The customer can choose to come to their facility and participate if they like.

Tail surfaces are likewise built up using ribs and skins bonded with adhesive, but they do use a few rivets along the trailing edges, mainly to keep things in position while the adhesive sets. The standard kit comes with the tail surfaces assembled, saving considerable time that the builder would use to construct jigs.

Wing assembly is done on a jig that holds the tubular spar. Ribs are fed onto the spar, then spaced using the jig that positions the trailing edges.

With the ribs squared to the spar and inserted in the trailing edge fixture, adhesive is applied to bond the substructure together before installing wiring and plumbing and bonding on the skins.

The landing gear on the -17 is a continuous hoop from right to left mainwheels, bolted to the fuselage and wing center section. The nosegear fastens to brackets on the firewall, and uses a rubber donut between the rudder pedals to absorb shock. The nosewheel is full castering, and ground steering is performed with differential braking.

Overall, the airplane is simple, strong, and looks easy to build—exactly what Jim Bede was looking for.

The Cockpit

The cockpit is fairly roomy for a single-seat airplane and the panel space more than adequate for any reasonable instrumentation such a light DVFR airplane would require. The demonstrator uses steam gauges for primary flight instrumentation and has a mount for an iPad mini in the middle for use as a moving map. The canopy is classic BD-5: Two hinged supports on the sides and a single arm in the rear allow it to swing up and back in a relatively level attitude. It swings forward and down to close and is latched with a single latch in the center. This works quite well, but I suggested that a stop be placed on the latch to prevent it swinging all the way around. As it is, the handle can swing forward when unlatched, catching under the windshield bow and preventing the canopy from being opened.

The panel in the BD-17L is quite spacious for a small, single seat airplane. An iPad fits in the center mount, but the airplane has plenty of room for all required flight instruments without it. The side stick makes for an uncluttered cockpit and works well, once the pilot adjusts to it.

There is plenty of room in the BD-17L cockpit for the modern human being. Seat adjustment must be done during construction or with cushions, a consequence of the simple design.

The controls are a mixture of the conventional and the unique. The throttle, flap, and trim levers on the left side of the cockpit are just what any pilot would recognize, along with the rudder and brake pedals. The side stick over on the right is more of a mystery to most. Angling out of the side console, it is a small-throw stick that works in the conventional manner—but you fly with just your hand, not your whole arm. In fact, it is better to think in terms of flying with just your palm and fingers; moving the entire wrist might be a little too much.

Some may be bothered before they fly it, with the fact that when the ailerons are neutral, the stick is angled about 45 degrees from vertical (unlike a normal center stick). Amazingly, once you are flying, it takes about a nanosecond for this concern to go away because we adapt that quickly and realize that neutral is sort of an arbitrary concept.

There are no seat or rudder-pedal adjustments, but fortunately I am about average in height and proportions, so everything fit fine. Like most homebuilts, adjustments can be made during construction if needed, and cushions can be used to fix fit issues once the airplane is flying.

The flap lever is low on the left side of the cockpit and allows four flap positions. Full flaps does not lower the stall speed by more than a couple of knots.

Flying the BD-17L

Climbing into the -17 isn't hard; it's very typical for a canopied airplane that requires you to lower yourself into the seat by holding onto the longerons. The cockpit is roomy and offers plenty of space for today's-sized adults.

The canopy latch can be opened from inside or out. It was just a little finicky to latch because the new canopy seals installed on the demonstrator made it hard to pull the canopy down to its seated position. A little tug makes it easier to start the latch process, and then the canopy pulls down easily. If the latch is not held in the right position, it can prevent the canopy from opening as it swings all the way around and blocks itself on the windshield. This is something that Jim Bede's son, Jim Jr., has added to his list of things to work on for future improvements.

The canopy latch has internal and external handles, and now has a stop to prevent it from swinging around and blocking the canopy opening when unlatched.

The engine starts easily, and has a very wide rpm range, so I wasn't surprised that I had to open the throttle quite a bit. Those used to Lycomings and Continentals that have an rpm range from idle to full throttle of less than 2000 rpm will have a little getting used to when working with the small, high-revving engines typical of most LSAs, but you can't be afraid to move that throttle to get the power you need.

Taxiing the airplane is done with differential braking and a swiveling nosewheel. The company airplane I flew had a problem with the left brake—it felt like a glazed pad and made it very difficult to turn left. This was probably unique to the airplane being flown, and the factory sent me a note a few days after I flew it saying they had overhauled both braking systems and everything is back to normal. I expected that, for almost all Bede airplanes steer in this fashion, and so long as you keep them in good shape, they drive around on the ground just fine.

On the day I flew the -17, it was bad enough that I planned all turns so that they could be made to the right if necessary. However, this is really a low speed issue, as once you have 15 mph of airflow over the tail, the rudder becomes effective, and steering is done with aerodynamics. The rudder throw is pretty small, but controls the airplane well. It should also be noted that the vertical tail is fairly large and can lead to weathervaning in a crosswind, so keep those brakes in good condition.

Bedecorp has set up a transition training plan for their single-seat airplane that involves taxi maneuvers on the ramp, followed by low- and high-speed taxi runs to help pilots become familiar with the side stick controller (see sidebar) and the sensitivity of the pitch channel before committing to actual flight. Checking new pilots out in single-seat aircraft is always a bit problematic, especially when the design is billed as sporty, so it is good that Bedecorp is thinking about this. It would be great if they had a two-seat transition trainer to accomplish the task, but for now, good briefings and practice at lower speeds is probably prudent. In my case, I did some of the preliminary taxi work and then proceeded to flight, based on previous airplanes with similar controls that I had flown recently.

As I do with all airplanes that have swiveling nose- or tailwheels, I lined up carefully and ran about a plane length down the runway to make sure everything was straight before adding power for takeoff. Once I pushed the throttle forward, the airplane accelerated like you'd expect for a Light Sport machine. Anticipating the potential for overcontrol on rotation, I let the speed build up a little over stall speed, then eased on just a little back pressure to raise the nosewheel. The airplane lifted off soon after with nary a bobble and climbed away with good performance.

The free-swiveling nosewheel is typical of Bede's tricycle gear airplane designs.

As expected, pitch forces were very light, and thus the airplane is very responsive in that axis. It is much heavier in roll (compared to pitch), so not very harmonious. Don't take the word "heavy" the wrong way, however—compared to almost anything else a private pilot is familiar with, roll forces are still light—but there is some notable throw of the stick required to roll the airplane. It doesn't take long to adapt to the lack of harmony, and with foreknowledge, the new pilot shouldn't get into any trouble.

The rudder is light, better than many airplanes that I routinely fly. It's not as light as pitch, but much lighter than roll. This particular airplane wanted to very slowly roll off to the right when flown hands off, but it was easy to compensate and pull the low wing up with rudder (at the expense of speed). The visibility out of the canopy was good, as I find with almost all of the single-seat low-wings. Even though I was flying early in the morning, the local heavy flight school traffic was already appearing as I departed the airport for a local practice area, and it was easy to spot traffic as the tower called it out.

The stabilator, coupled to the side stick, accounts for the very light pitch forces—delightful to fly once the pilot is used to them.

Leveling off in the practice area, the first order of business was some clearing turns to get the feel of the airplane and see how quickly it responded to control inputs. The airplane holds altitude in normal turns surprisingly well, considering the light pitch forces. Once trimmed, it stayed put with almost no back pressure. I tried progressively steeper turns in both directions, and roll control was positive, as was the roll stability. It tended to want to return to wings-level flight up to about 30 degrees of bank, was fairly neutral up to about 45 degrees, and then you needed opposite aileron to keep it from steepening the bank beyond that—very normal for this class of airplane.

Next up was slow flight and stalls. Once again, the airplane seemed mild-mannered, with a mild break and no tendency to try and spin when stalled power off—either straight ahead or in turns. The same held true with power-on stalls, but then again, there isn't a lot of power available to do much of anything exciting in the stall. Break the stall with elevator and climb back out once the wing is flying, and you're done.

With the feel of the airplane in hand, I turned to stability checks. Pitch stability—hands free—showed a very slow phugoid with little damping, but positive. The diversions were very small, so I would expect the airplane to hunt in altitude a little bit, but not diverge. With the large vertical fin, the yaw stability was excellent as well, and roll held no surprises. It was time to get more aggressive, single-seat airplanes being the type to inspire fighter-pilot tendencies.

Of course, you can only get so aggressive with 65 hp. Like any low-powered LSA, the margin for maneuvering is not huge, so you don't have the excess energy you'd have to wind it up in a steep turn or pull from level flight into a steep chandelle or wingovers. But the airplane has good manners for what it can do, and I did steep turns of 60 degrees of bank for about 180 degrees before running out of energy. It is in the coordination maneuvers like chandelles and lazy eights that the lack of harmony between pitch and roll were most noticeable, but one quickly adapts and compensates. These maneuvers demand constant coordination, and after you do a few turns, you'll have a good feel for how much control in each axis is required.

The Engine

The HKS engine is a two-cylinder, four-stroke, dry-sump engine with dual electronic CDI for ignition. It performed wonderfully throughout the flight, although there was a slight tendency towards roughness at idle speed. Jim Bede Jr. attributed this to a slight problem in synchronizing the twin carbs, but it was easy to simply let the airplane idle a little fast. Full power operations were just fine, and when I was out in the practice area, I let it wind up in level flight to see 120 mph on the airspeed indicator, with the tach showing 6200 rpm. Comparing this 65 hp engine to a Continental of the same horsepower installed in a J-3 Cub will show that the 17L is almost twice as fast. Then again, it's probably less than half the size.

The airplane is currently sporting straight exhaust pipes with no muffler, and it is pretty loud to people on the ground. I could hear it departing for several miles when the test pilot left the airport to check it out. The original muffler for the HKS engine didn't fit inside the cowl, along with the oil tank, so they are having a new, smaller muffled exhaust built that should quiet things down quite a bit. Cockpit noise levels were about as high as a typical aluminum homebuilt with no interior—loud, but tolerable.

With the air work finished, it was time to head back to the airport to see how the little plane lands. Traffic was an issue, so I didn't have a tight closed pattern to myself, and with the braking problems I was having, I didn't want to tempt fate by doing too many turns around the patch anyway. Slotted behind two other airplanes flying large patterns, I had a long time to stabilize the approach, and with flaps out, it was fairly easy to stay on speed and on glideslope. I noted no unfriendly tendencies in the flare, and even with the winds beginning to come up, the rollout was straight—undoubtedly helped by the big fin.

The low wing in a single seater like this is always very close to the ground (since everything is small), so ground effect is a noticeable variable in any landing. Staying on speed and not getting too fast will help a great deal in making good landings. With the sensitive side stick, the novice BD-17L pilot will want to make sure that they keep their arm firmly on the armrest and flare with just the fingertips and a little pressure, or ballooning will result. Getting a good checkout in another sensitive airplane before flying the BD-17L would be a good idea to make the first landings suspense free.

Small, Light, and Simple

In the end, the BD-17L is just the airplane its designer set out to create. It is sporty, easy to build, and simple to maintain. Designed around the HKS engine, the airplane preforms just fine, but potential owners should be aware that they need to learn a lot about the powerplant themselves, for at strange fields, you might get blank stares if you ask for help on anything but a Lyc or Conti.

Performance-wise, the BD-17L is great for cruising around the local area, and the factory says that one fellow they know used his as a commuter in the Florida area. Setting out on a multi-day cross-country will be an adventure—but people have done this with much slower airplanes since the days of the Wrights.

Bedecorp has been around since the 1960s, and yes, Jim Bede Sr. attracted controversy because of the failure of the BD-5 project that left many dreamers out their deposit with nothing to show for it. But many of those dreamers picked themselves up and decided that, by gum, aviation was important to them, and they'd find something else to fly! In that way, Jim Sr. inspired a lot of today's aviators—some might argue the hard way—and while they didn't get their personal spaceship, they found something else that worked for them just as well. The BD-17L is worth a look to see if it fits your size, style, and budget for a fun machine with which to take wing.

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