October 1, 1999
In the seemingly eternal quest for the quiet cockpit, a few owners of high-end turboprops have opted for cabin noise-canceling systems. But at a cost of $35,000 for these systems, owners of smaller airplanes are, shall we say, not interested. However, a new company called Quiet Flight LLC has introduced what it claims is the first affordable cabin noise-canceling system, with a price tag starting at $4,995 for single-engine airplanes.
Cabin noise-canceling systems take to a large scale the same technology used in noise-canceling headsets. Similar to the headsets, Quiet Flight's system fights noise with noise. Incoming racket passes through a microphone to a processor, which transmits to speakers a signal 180 degrees out of phase that essentially cancels out much of the incoming noise. Unlike headsets, which cancel noise in a volume of air that's no more than a few cubic inches, the cabin noise-canceling system must combat the racket in the comparatively stadium-like volume of an airplane's cabin. In addition, the Quiet Flight system reduces the propeller-related vibrations that bombard the entire upper body, whereas headsets protect only the ears. It's this pounding the upper body takes that can cause headaches and fatigue after long flights, say Quiet Flight representatives.
Quiet Flight's system uses Cooper Tire and Rubber Engineered Product Division's Envisys (Electronic Noise and Vibration Intelligence System) technology. So far, permanent installations have been awarded supplemental type certificate (STC) approval in the Cessna 210. STCs for 40 other popular general aviation airplanes are in development and expected to be approved over the next three years.
Quiet Flight allowed AOPA Pilot to take a demonstration flight in a 210 with a permanently installed noise-cancellation system. A microphone and speaker were mounted in the head-liner above each of the 210's four front seats, with the speakers straddling the wing-spar carrythrough. The speaker and microphone installation was tidy in the demonstrator and would likely be completely unnoticed by nonpilots. Speakers also can be hidden behind a cloth covering instead of by a speaker grille (as pictured here). A processor box is located remotely. In the demonstrator 210, it was located in the baggage compartment and took up little floor space. The box can be installed in a less obvious place. The entire system weighs about 30 pounds.
We took a 30-minute flight in the Quiet Flight-equipped 210 — sans headsets, of course — and liked what we heard — er, didn't hear. Although the difference won't make you drop your hand mic in disbelief, during our demonstration Quiet Flight lowered the overall noise level in the cockpit area by a solid four decibels, from 92 to 88 dBA, as tested with a handheld decibel meter. In the rear seat area, which is much quieter to start with, we measured a 2-dBA reduction from 86 to 84 dBA. The portable decibel meter measures total noise only and therefore cannot measure noise within a certain bandwidth.
In studies used for certification, Quiet Flight determined that propeller noise (in the 120-Hz range) was reduced 27 dB on the C-scale, the scale used to measure a discreet frequency. In testing of the Cessna 310, the company claims a 33-dBC reduction.
Quiet Flight claims that in optimal conditions the system will knock six to nine decibels off the total cabin noise. If that kind of performance can be met and atmospheric conditions allow, that is equivalent to a 50- to 65-percent reduction in sound-wave pressure. Although it fell short of the total noise- reduction claims on our test flight using crude measurement methods, the system makes flying GA airplanes without headsets a viable option. We noted that when the system was turned on, conversation in the normally aspirated 210 could be conducted with far less voice elevation. It wasn't conversational, but it was darn close.
The Quiet Flight system, like the $35,000 systems used in high-end turboprops, has zonal coverage. In other words, it only attacks noise at the upper-body level. If you lean down to fetch a chart, for example, the noise level returns to normal. Once back in the "comfort zone," the noise subsides again.
Currently, Quiet Flight works in airplanes equipped with three-blade propellers. Sometime later this year, STCs are expected to be obtained for airplanes equipped with two-blade props. Quiet Flight should work much better in airplanes with two-blade props since the two-bladers produce a larger sound wave (80 Hz), resulting in a lower rumble than in airplanes with three-blade props. One caveat, however, is that the efficiency of active noise canceling is directly related to the size of the speakers. Since speaker size may be limited by installation space in some airplanes, your results may vary.
Quiet Flight's noise-canceling system draws less than seven amps when working, making power draw a minimal concern. Besides, the system turns itself on and off automatically based on RPM. In the 210, the system begins working at around 1,900 rpm and turns itself off above 2,600 rpm. At lower than 1,900 rpm, the system simply is not needed. At higher than 2,600 rpm, Quiet Flight assumes that the pilot is requesting the maximum amount of power from the engine and the system cuts off, thereby unloading the alternator.
Along similar lines, Quiet Flight is also working on a voice-enhancement system that will amplify words spoken by those in the cockpit, which will reduce the need to raise one's voice in order to be heard by passengers who may be seated two rows behind the pilot and vice versa.
Quiet Flight's 310 is equipped with a portable system, while the approval for that application's permanent system is under way. For twins, the system costs $6,995 and employs one additional sensor in the exhaust for synching of the prop noise.
From an economic standpoint, we believe that the Quiet Flight system is reasonably priced. If you were to place a high-quality ANR headset, such as the Bose X, at every station in a six-seat airplane, it would cost $1,000 per seat — more than the $4,995 cost of the Quiet Flight system in a complex single. Although the headsets do a better job of protecting your ears, the Quiet Flight system does a better job of protecting your entire upper body from sound bombardment. Although we didn't try it, we would assume that wearing a headset (noise canceling or not) in the Quiet Flight cabin would further reduce noise. For those who simply don't like wearing headsets, whether it be for comfort or coiffure-crushing reasons, the Quiet Flight package is the only game in town — for now.
Quiet Flight is currently training technicians for installation centers that it is establishing around the United States. Installations will require a technician to tailor the system to your airplane via a laptop computer. For installations that are not yet STCd or for those owners not willing to sacrifice their headliners until the system proves its mettle, Quiet Flight will sell you a portable system for the same price as the installed version. Buyers of the portable system can later exercise a no-cost option to trade up to the permanent system after the STC paperwork is signed.
Overall, we think that this is breakthrough technology for GA airplanes. Technology that was once cost-prohibitive for owners of light airplanes is now available for a fair cost. If Quiet Flight's technology becomes a part of cockpits in the future, the noisy reputation of light airplanes may finally fade.
For more information, contact Quiet Flight LLC, 3901 Stanford, Dallas, Texas 75225; telephone 214/521-5788; or visit the Web site ( www.quietflight-llc.com). — Peter A. Bedell
Insight Avionics recently began shipping its new-technology, brighter-display Strike Finders. Buyers of the Strike finder lightning detector now have a choice between the original display and the new one, which is 40 times brighter, according to Insight.
A typical electronic display found on an electronic flight-instrumentation system, for example, has a brightness of 100 foot-Lamberts — the scale used to measure brightness. The new Insight display outputs 2,000 foot-Lamberts.
The new display commands a $1,500 premium, raising the list price of a Strike Finder to $6,495. Some dealers have priced the units at about $6,000. Owners of older Strike Finders can upgrade to the new display for $1,500. The upgrades can be done only at the Insight factory by sending your unit to Buffalo, New York.
According to Insight President John Youngquist, the new solid-state Ultra Bright display has a virtually unlimited life, is immune to vibration, and does not degrade as it ages. Among the advantages of the patented Ultra Bright display is the ability to increase the brightness while using less power and creating no more heat than the old displays. The new display does not wash out in sunlight, according to Youngquist. In addition, the display can be dimmed automatically over a greater spectrum, meaning that it can be brighter during the day and dimmer at night than other displays. In addition, the new display is compatible with night-vision goggles, making it highly attractive for military applications.
For more information, contact Insight Avionics, Box 194, Buffalo, New York 14205-0194; telephone 905/871-0733, fax 905/871-5460; or visit the Web site ( www.strikefinder.com). — Thomas B. Haines
Want to try before you fly? You've heard glowing reports on the Garmin 430 color moving-map GPS, but maybe you would like to see it for yourself. Garmin International offers an interactive training CD that is also packed with the unit. For $49, you can set up a Garmin 430 Simulator on your home computer and follow instructions in your own copy of the pilot's guide. It is available directly from Garmin or through your local avionics shop. To order, telephone 800/800-1020 or 913/397-8200; or visit the Web site ( www.garmin.com). — Alton K. Marsh
Monroy Aerospace of Coral Springs, Florida, has introduced the ATD-200, a new portable traffic-avoidance device. The automotive radar-detector-size unit can be placed on the glareshield for temporary installations or mounted in or under the instrument panel with a remote antenna for a more permanent installation. Monroy claims a three- to six-mile detection range depending on the strength of the target's transponder. A female voice says into your headset, "traffic," to alert pilots when traffic is within three miles. When the intruder gets closer than one mile, a "traffic nearby" message is given. The ATD-200 lists for $895 and works on 11 to 28 volts. There is a 30-day, money-back guarantee and a three-year warranty provided with purchase. For more information, contact Monroy Aerospace at 954/344-4936. — PAB
We've all seen chart clips for airplanes with standard yokes, but now Sky-Jockey Products has introduced the Stick Jockey. Pilots of stick-controlled airplanes can now have approach plates, charts, checklists, handheld navigators, and other items mounted right in front of them. Two models are available to accommodate three-quarter-inch or 1.5-inch-diameter sticks. Stick Jockey lists for $24.95. For information or orders, contact Sky-Jockey at 310/276-6638 or send an e-mail ( email@example.com). — PAB
Unless otherwise stated, products listed herein have not been evaluated by AOPA Pilot editors. AOPA assumes no responsibility for products or services listed or for claims or actions by manufacturers or vendors. However, members unable to get satisfaction regarding products listed should advise AOPA. To submit products for evaluation, contact: New Products Editor, AOPA Pilot, 421 Aviation Way, Frederick, Maryland 21701; telephone 301/695-2350. Links to all Web sites referenced in this issue can be found on AOPA Online ( www.aopa.org/pilot/links/links9910.shtml).
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