AOPA's Ultimate Arrow Sweepstakes
The Ultimate Arrow gets a facelift
BY PETER A. BEDELL (From AOPA Pilot, August 1997.)
An important goal in turning AOPA's sweepstakes Piper Arrow into the Ultimate Arrow is to improve the performance and safety of the airplane. Recently applied speed modifications took care of upping the performance ante, while vastly improved exterior lighting makes the Ultimate Arrow more conspicuous during both day and night operations.
By far the most obvious modification to the Arrow is the new cowling. Designed, in part, for the Ultimate Arrow Sweepstakes by LoPresti Speed Merchants, the so-called "Now Cowl" will be available for all models of normally aspirated Arrows, regardless of the type of propeller installed. According to LoPresti, the cowling modification is good for about 6 to 7 knots at full throttle at sea level. At normal cruise settings and altitudes, you can expect to see a smaller speed increase. Regardless, the cowl does help to reduce drag and greatly enhances the appearance of the Arrow's nose.
The all-composite cowl incorporates a single cowl flap, something the old cowling lacked. In the stock cowl, engine cooling air would exit downward through the nose gear wheel well at a 90-degree angle to the oncoming air. The LoPresti cowling ushers cooling air in through the small circular inlets at the front and out through the cowl flap at a rearward angle, helping to reduce drag. Although the cowl flap is one more thing for the pilot to remember, it allows better control of engine cooling. And if it can eke a few more knots out of an otherwise speed-challenged airframe, who's to criticize?
One of the nicest things about the LoPresti cowl is that it is made from high-quality composite materials that should not crack under the day-to-day rigors of vibration and thermal or flight loads, something Piper owners have lamented for years. The Ultimate Arrow's original cowling had its share of cracks around the oil-access door and had some large chunks of fiberglass missing from the front of the cowl, ahead of the attachment pins. We've seen other Piper cowls that have been patched so many times that they resemble something from Dr. Frankenstein's lab, and that raises the question of how safe they really are.
Further enhancing the safety and convenience of the Arrow, LoPresti's cowling incorporates access doors for easy engine preflights without requiring the removal of the entire top cowl. For those who don't like to use a screwdriver during the preflight, there are quick-access panels for the oil dipstick and gascolator drain. LoPresti continues to tweak the design, hoping to get better than 8 knots out of the cowling mod. Expect to see a list price of around $7,000 for the cowl kit, which includes a spinner and backplate.
Also added to the Ultimate Arrow were underwing modifications from LoPresti. LoPresti and Knots 2U make similar products such as gap seals, main-landing-gear fairings, and flap-hinge fairings. Our reason for using LoPresti's underwing products was based largely upon the fact that the airplane was already going to be at the Speed Merchants' shop for 2 weeks for the cowl installation. Many independent shops will install these modifications too.
Under the wing we added LoPresti's flap-gap seals (called Speed Seals), landing gear fairings (Speed Spats), and flap-track fairings (Speed Splitters). The combination of these products is claimed to raise the top speed of the airplane by about 8.5 knots. Some customers also claim that these underwing modifications whether from Knots 2U or LoPresti also increase the rate of climb. Both companies also offer aileron-gap seals; however, concerns about trapped water turning to ice and freezing the controls kept us away from such a mod.
The crew at Mod Works in Punta Gorda, Florida, who performed most of the refurbishment work on the Ultimate Arrow, added Knots 2U's wing-root fairings, which smooth out the somewhat blunt joint between the wing root and the fuselage. Besides enhancing the Arrow's appearance, the fairings are claimed to add 2 knots to the airplane's top speed. On the top of the vertical stabilizer, Knots 2U's Slimline strobe light replaces the obtrusive old beacon light. Knots 2U will provide either a white or a red lens for the unit we chose the red lens for less obnoxious ground operations at night.
Out on the tip of each wing we installed Whelen Engineering's Model A600 light assembly that contains forward- and aft-facing nav lights and a strobe light. This is a popular unit for homebuilders because one mounted on each wing covers all of the position/strobe lighting requirements imposed by the Federal Aviation Regulations. In the Ultimate Arrow, these are connected to a new Whelen Comet-Flash strobe power supply. The Comet-Flash system flashes each strobe four times in rapid succession for maximum visibility. For those wondering why we chose to install two additional aft-facing nav lights in the wing tips (there's already one installed in the trailing edge of the rudder), it is simply because the Arrow despite all of the speed mods by LoPresti and Knots 2U is still most likely to get run over from behind.
Also enhancing the visibility of the Ultimate Arrow are new RMD fiberglass wing tips housing landing and taxi lights. These wing tips contain low-wattage landing/taxi lights to be used as recognition lights. These are connected to a Precise Flight Pulselite system that sequentially pulses the lamps on and off, alternating between left and right wing tips. When in the pulse mode, the bulbs do not completely extinguish; rather, they are dimmed, which should provide longer bulb life. Flip the Recog light switch on the Ultimate Arrow's panel and the wingtip lights burn steadily for night takeoffs and landings. RMD wing tips can be ordered with larger bulbs; however, the Arrow already had a landing light in the cowling, and we did not want too much candlepower to place undue strain on the alternator.
Low-wattage wingtip lights or not, with all of this lighting equipment and the many bells and whistles already installed in the panel (see "Ultimate Arrow: An Inside View," June Pilot), alternator overload quickly became a concern. National Airparts came to the rescue with its 14-volt alternator that supplies a whopping 100 amps of power. It happily powers all of the lighting and avionics without a budge of the ammeter.
In all, the additional lighting will make the Arrow a safer airplane on the ground, in the air, and for the pilot in the cockpit. No longer will the pilot be caught in the dark when the sole landing light burns out. Likewise, traffic from all around will have a hard time missing the Comet-Flash strobes and recognition lights. The exterior lighting, combined with the capability of the panel, will make the future owner of the Ultimate Arrow far more confident during night operations.
AOPA would like to thank the following companies that donated or discounted their lighting and speed mod products for the 1997 Ultimate Arrow Sweepstakes:
Slimline beacon light, wing-root fairings, stabilator seal
Cowling, flap-gap seals, gear fairings, flap-hinge fairings
Installation of all mods (except LoPresti)
Alternator (100 amp, 14 volt)
Standby vacuum system, Pulselites
Wing tips with landing/taxi lights
Lighting (position lights, strobe lights)
How much $$ does it take to get KTAS?
When we obtained Arrow N6383C in late 1996, it wasn't as fast as the pilot's operating handbook advertised, according to our true airspeed calculations. In fact, it wasn't even close. If our airspeed indicator and pitot-static system were correct, it was about 7 to 8 knots slower than book. Unfortunately, most of our "before" figures became skewed after the installation of a new airspeed indicator, remanufactured engine from Lycoming, 3-blade Hartzell propeller, and many other modifications that have taken place in the past several months.
Logically, the only way to test the Ultimate Arrow was to fly it against another Arrow. We tracked down a 1977 Arrow III owned by AOPA member Jim Saboe of Ellicott City, Maryland. Finding a totally unmodified Arrow is tough, and sure enough, Saboe's Arrow has Knots 2U's flap-, aileron-, and stabilator-gap seals as well as the company's wing-root fairings all of which are said to increase an Arrow's top speed by more than 8 knots.
AOPA's Ultimate Arrow lacks the aileron-gap seals of Saboe's airplane but has the LoPresti Now Cowl and landing-gear fairings (Speed Spats). Our test involved flying the airplanes at full throttle and 2,700 rpm in formation all the way up to 8,500 feet, stopping at 2,500, 4,500, and 6,500 feet for cruise-speed tests. We noted rate of climb, indicated airspeed, groundspeed, temperature, and other parameters at each altitude. Each airplane carried two pilots and full fuel (72 gallons).
Climb rates for the two Arrows appeared equal from sea level all the way to 8,500 feet, but it was in cruise that the Ultimate Arrow would begin to put the moves on Saboe's Arrow. After we leveled off and closed the Ultimate Arrow's huge cowl flap, it began pulling away at every altitude. By how much? Frankly, it was somewhat disappointing to see that the Ultimate Arrow was only about 3 to 5 knots faster than the other Arrow, depending on altitude. What was even more disappointing was that both of these airplanes, with their various modifications, were still a few knots slower than book speeds. It makes you wonder how realistic or optimistic the operating handbooks were in the 1970s.
At a typical cruise power setting of full throttle and 2,400 rpm, our Arrow mustered 136.5 knots at 7,500 feet. Suspicious of an erroneous airspeed indicator, we took exhaustive notes of all of the same parameters, as well as GPS groundspeed at various altitudes and headings, and used them to determine that the airspeed indicator reads about 2 knots slow. This being the case, we deduced that we have a 138-knot airplane at typical cruise power settings 1 knot slower than book at this particular altitude.
LoPresti's before-and-after figures, using a calibrated sensitive airspeed indicator, show that the Ultimate Arrow gained about 8.5 knots. We can't back that claim accurately because our airplane has been so extensively modified and the original airspeed indicator (the one we used for the before tests) was removed. We do know, however, that the Ultimate Arrow is 3 to 5 knots faster than another particular Arrow III.
But, what does it cost to get this kind of speed? If we take the total cost of all of these mods and divide it by LoPresti's 8.5-knot figure, we find that each knot will cost more than $1,000. This is assuming LoPresti charges at least $6,000 for the Now Cowl. That $8,600 could buy a lot of avgas, but the reason most of us fly is to go fast. PAB