Just when it seems that every configuration of an airplane has been thought of, built, flown and perhaps found to be inferior, or at least no better than current designs, someone comes up with a new twist on an old idea that evokes a visceral response: “That’s cool. I want to fly it!” That was exactly the response that I had at first sight of the newest addition to the Velocity Aircraft lineup, the V-Twin.
Before beginning the never-ending debate of the single versus twin, let’s call a truce and acknowledge that there are those (myself included) who, for whatever reason, have decided that the additional expense of operating a second engine is offset by the comfort that comes from operating a multi-engine airplane over cold water, rocks, trees and any combination thereof, especially in low IFR or at night.
Further, full disclosure requires a confession that canard-type airplanes, like those in the Velocity family, do not occupy the top spots on my favorites list. But I had seen a small concept model and some pictures of the airplane, and viewing it in person at Sun ’n Fun 2012, shortly after its first flight, set the hook. Soon after, we took the newest addition to the light-twin market for a spin.
The V-Twin fuselage is shared with the other members of the Velocity family, as is the landing gear and many of the systems. Aside from having two pusher engines mounted on the wings, the most obvious difference between the V-Twin and its other family members is the absence of the winglets and associated rudders, which are replaced by a dorsal-mounted vertical stabilizer and conventional center-mounted rudder.
This arrangement gives the airplane the appearance of being more compact, but in reality, it has 4 feet more wing than the Velocity TXL-5 that we flew for a report in the August 2010 issue. The look is aesthetically pleasing and appears more balanced than the single-engine versions with their flat-topped fuselages and tall winglets, which Beechcraft called “tipsails” on its ill-fated Starship. There is no mistaking the resemblance between the V-Twin and the Starship, but the center-mounted vertical stabilizer and rudder differentiate it.
Demo pilot John Abrahamsen and company founder Duane Swing pose in front of Velocity Aircraft’s newest design.
A nice-looking airplane is important for sales, but what matters is how it flies. So after a quick walk around, it was time to fly it. Sit down seems strange because we are accustomed to crawling into an airplane to fly. With the V-Twin, like all Velocity aircraft, it is simply a matter of sitting down in the seat. Ease of entry, especially for the front seats, is excellent.
The first V-Twin was equipped with an MGL Odyssey EFIS, and the panel was uncluttered. The throttle quadrant was textbook twin, and the mag and start switches, as well as most of the electrical system, were mounted in the overhead panel. Pilots visually impaired with “short arms” and bifocals will memorize the switch positions, swear a lot or build their own V-Twin with the electrical system in the panel. All the circuit breakers are cleverly concealed where they can be easily accessed under the armrest between the seats.
The two IO-320 Lycomings light up easily, and the composite MT propellers make little noise at idle power. Taxiing is accomplished with differential power, and brakes when needed. The second engine makes taxiing much more pleasant and precludes the need to drag a brake in all but the strongest crosswinds. Soon we were at the end of the runway and it was time to close the big gull-wing doors, runup and go fly.
The runup is straightforward. The pitch trim is a spring system, and the elevator on the canard is in plain sight. Just like the singles, set the elevator one finger width below trail for two in the cabin and two fingers below trail for four. Both engines are fed from a single fuel system made up of two 48-gallon tanks in the wingroots and a 5-gallon header tank. On the prototype, a single boost pump fed both engines, but most likely builders will install a boost pump for each engine on subsequent aircraft. With mags and the prop feathering checked, all that remained to do was fly.
The uncluttered panel has ample space for even the largest displays like the MGL Odyssey in the factory demo.
With two pilots on board, 60 gallons of fuel and some baggage, the airplane was 600 pounds below its 3200-pound gross weight. There was room on the weight and balance for two more passengers and the 40 gallons of fuel required to top off the tanks.
Multi-engine airplanes tend to have the low pitch stops set at a flatter blade angle than singles because if the engine fails, the affected propeller can be feathered. This lower blade angle means that the engines spin up quickly. In spite of only having 160 horsepower each, at 2600 rpm the acceleration was brisk.
The elevator was effective quickly, and the airplane rotated smoothly and climbed effortlessly. The internal friction and the aerodynamic forces combine to make the control pressures on the side-stick controller heavy, but not objectionable. Canard airplanes tend to be a little sensitive, especially in pitch, so some heaviness is welcome in that axis.
The little bit of noise the full feathering MT composite propellers create converting horsepower into thrust is left in the wind behind the airplane.
What was noticeably different from the XLT-5 handling was the rudder. The rudders on the tipsails of the single-engine airplanes deflect outward only, and only on one tip at a time. These control surfaces have little effect on yaw initially, and the result is a large dead band in the rudder authority. The central-mounted vertical stabilizer on the V-Twin is sized to accommodate up to 230-hp engines, so the airplane is very stable in yaw, and the rudder response is proportional and well harmonized. The result is an airplane with much more pleasant handling than the single-engine stablemates.
Also remarkable in the V-twin was the absence of noise. The occupants share the fuselage with the engine in the single-engine variants, but the engines on the V-Twin ride out on the wings, outside, and behind, the cabin. The noise that they do make is carried away with the wind. The composite fuselage is an excellent acoustic insulator, and the smooth shape of the fuselage parts the air with minimal disturbance. These factors combine to make an airplane that is comfortably quiet.
Comfortable is a word that accurately describes all of the Velocity aircraft. They are designed to be cross-country cruisers. This means that the seats sit erect for maximum comfort on long traverses. The noise level is low, the fuel tanks are large, and another factor in comfort is peace of mind. That comes from the knowledge that should an engine expire along the way, the other engine will allow a landing at the point of the pilot’s choosing rather than whatever is available within the glide radius of the airplane.
Two for One
Engine-out options are not the only reason why people opt for multi-engine airplanes. Twin-engine airplanes are supposed to be fast, and in many cases they are, but the story is not that simple. Take the Beechcraft F-33 Bonanza and E-55 Baron. They share the same fuselage and the same engine, and even so the Baron is faster. The F-33 flies 170 knots and at the same power setting, the Baron might be 15-20 knots faster.
It would be easy to compare the speed of the V-Twin, with its two 160-hp engines, to the Velocity XL with a 300-hp engine. But that would not be fair. A fairer comparison would be between the V-Twin and the Velocity XL fitted with an IO-320. Clearly nobody is going build one of those, but the point is that there is a penalty to pay for splitting up the horsepower between two engines and propellers.
Velocity says the V-Twin will fly 185 KTAS at 75% power. We flew the airplane at 2500 rpm and wide-open throttle, yielding 24.5 inches manifold pressure. Admittedly, there was some turbulence that might have slowed the airplane, but using the three-leg GPS calculator, we found 175 to be a more realistic number. Again, before anybody says it, a 300-hp Velocity XL would do 200 KTAS on the same horsepower and slightly less fuel flow. Even more impressive is that an XLT would do 250 KTAS at FL 250 on only slightly more fuel flow. But the question that twin owners ask is not how fast they go, but how far they fly with one engine inoperative.
That meant it was time to pull one of the red levers back, feather a prop and fly on one engine. Much noise is made about the difficulty and danger of flying multi-engine airplanes after an engine failure. The V-Twin handles very nicely on one engine. The engines are close together and Vmc red radial on the airspeed indicator was at 82 knots.
Because of the pusher configuration and the right-turning engines, unlike a conventional tractor configuration, the right engine is critical. This is because as the angle of attack increases, the center of thrust of the operating engines moves left instead of right (the angle of attack increases as the blade descends and decreases as it moves upward). In the case of a left-engine failure, the center of thrust of the right engine moves farther from the centerline of the plane. The slower the airplane is flown, the higher the angle of attack and the more rudder pressure is needed to keep the airplane straight. Yet as the airplane slows, the rudder loses effectiveness, requiring more rudder deflection. More rudder deflection increases drag, which slows the airplane and requires increased angle of attack, which moves the center of thrust farther from the centerline, which…. This vicious circle should be avoided at all costs during engine-inoperative flight in a multi-engine airplane.
While the V-Twin’s side-by-side engine configuration does not make it immune from this phenomenon, the closeness of the engines to the centerline and the ample vertical stabilizer and rudder minimize these concerns. The V-Twin handles and performs very well on one engine. At the weight we were flying, the airplane would climb 100 fpm at 7500 feet with a 9500-foot density altitude.
Back to Two Engines
The engine started easily in flight and we warmed it up so that we could do some slow flight and stalls. In the case of the canard airplanes, “bucks” might be a better word than stalls. With full up elevator and idle power, the airplane lacked the up-elevator authority to stall the canard and the airplane started to settle at about 1000 fpm. Adding power pushed the nose up farther, and just below 80 knots, the canard could no longer support the nose of the airplane and it settled more than stalled. When we decreased the angle of attack of the main wing, the airplane accelerated, the canard created lift and the process repeated itself, or bucked, until the aft stick force was relaxed. At max power, the airplane was climbing as it oscillated in pitch. The advertised stall habits of the canard types are preserved in the V-Twin.
One thing you won’t find on Velocity aircraft is flaps. Flaps could reduce the stall speed of the main wing, but if the stall speed of the main wing got below the stall speed of the canard, ugly things could happen. As a result, none of the Velocity aircraft are short-field airplanes. The Beechcraft Starship dealt with this problem by sweeping the canard in cruise and spreading it when the main wing flaps were deployed. The technical challenges of that would be pretty great in an Experimental/Amateur-Built airplane.
While we were in the slow-flight regime, I pulled the right engine to dead idle and pushed the left up to full power and began slowing. Typical of most light twins, the first indication of Vmc was a yaw event that was very benign. The small engines combined with the density altitude lacked the power to induce any kind of a dramatic event.
As the airplane matures and the horsepower grows, careful exploration of the Vmc characteristics of this new multi-engine configuration would be warranted. But the current airplane appears docile and forgiving in all the flight regimes we explored.
A tab on the canard elevator improves pitch handling and is affectionately called the “Sparrow Strainer.”
Down to Earth
With the airwork complete, it was time to come down. All of the Velocity aircraft share a 200 KIAS redline. The airplane is very slippery and quiet, and Vne can be achieved or exceeded easily. Without speed brakes, power must be reduced to come down, and having two propellers with flat, low-pitch settings means, if needed, the airplane can come down quickly. Velocity test pilot John Abrahamsen reported that with both engines at idle and the gear down, the terminal velocity of the airplane is less than 120 KIAS. That would be an impressive descent profile. The naturally aspirated -320 Lycomings are robust engines and would tolerate low-power descents well, but again, as the airplane matures and more power or turbocharging is envisioned, like the XLT, decent planning will be critical.
Entering the pattern, the airplane slowed easily to the 120-knot gear speed, and the electric hydraulic power pack deployed the landing gear. The mains touched and my effort to hold the nose off was too little too late, and it came down sooner than I wanted.
The V-twin shares many systems with other Velocity aircraft, such as the landing gear and retraction system.
We taxied back for takeoff, and at 400 feet I pulled the right, critical engine to just short of idle to simulate something less than zero thrust. Turning left into the good engine to fly a left-hand traffic pattern required outside aileron and rudder, and the geometry of the side stick made that uncomfortably heavy, but definitely doable. Had the airplane been at its maximum gross weight of 3200 pounds, like nearly all light twins, the performance would have been marginal at best. But at more typical weight, the performance was very good, and the handling characteristics were well within the capabilities of a proficient multi-engine pilot.
Landing Velocity airplanes is an acquired skill. But either I am learning or this one is easier, because I had much better results in it than in the XLT. Maybe the additional 4 feet of wingspan needed to move the center of lift aft to accommodate the weight of the engines tames the landing a little, and the rudder authority makes compensating for a light crosswind easy. Whatever the reason, flying a 90- to 100-knot approach, squeezing the power off to an 80-knot touchdown and a tugging on the stick at the precise moment will hold the nose in the air for a relatively pleasing arrival.
Without flaps, the airplane rolls, but the brakes are effective, and while the V-Twin is not in any way a short-field airplane, I was able to turn off at midfield on a 5500-foot runway with reasonable braking.
I had a smile. The airplane is pleasant, and while it lacks the blistering speed of the XLT, it offers something almost unheard of in kit aircraft: the security of a second engine. Flying a single-engine airplane with a 70+-knot off-airport landing speed and a highly stressed turbocharged engine is not a risk everyone is willing to accept. The simple, naturally aspirated IO-320 is one of the most robust aircraft engines ever built. Having two of them on an airplane that flies pretty well, with one caged, offers a security that is hard to ignore when the travel plans call for mountains, trees or cold water in low IFR or the dark.
Offering multi-engine security in a package with the cabin space and creature comforts that Velocity has in all of its aircraft yields an airplane that has a place in the market. It won’t be for everyone, and the canard purist will loathe the dorsal vertical stabilizer. Many will want more power and more speed. But stay tuned. Chances are the V-Twin will get it.
Our intrepid photographer, Richard VanderMeulen, shot more photos than we can fit in the print edition of Kitplanes, so we’re including them exclusively in the online article. Click on the image above to see the Velocity V-Twin bonus web gallery.
For more information, call 772/589-1860, or visit www.velocityaircraft.com.