Screen Resolution
Once again, you have done an evaluation of a new GPS unit (Garmin GPS 295) and you have included a comparison chart of all the competing hand held GPS units features and specifications but youve left out one of the most important quantitative specifications: the resolution of the displays. I believe this is more important than the size of the display.
A small high-resolution display can display a surprising amount of information without becoming cluttered and unreadable. I fly with a 10-year-old Argus 5000 which is still state-of-the-art except that its monochrome.
Its display resolution is 512×256 pixels. And although rather small, it allows for a surprising amount of information to be displayed clearly on its CRT display. At AOPA Expo last fall, I spent some time looking at the Garmin 430 and while I was impressed with the overall package, I was not impressed with the quality of the LCD display.
I found that the display used on the GNS 430 is a DTSN display with a resolution of only 240×128 pixels resulting in a pixel pitch of .38x.38mm. The display on the 530 is a TFT active matrix display of 320×234 pixels.
The display on the 295 has a resolution of 305×160 pixels which, using the height and width you have published, results in a pixel pitch of .28x.28 mm. The three-year old notebook Im typing this on has a pixel pitch of .19x.19mm. The bottom line here is that Garmin is using display technology that is far from state-of-the-art.
The other area where some confusion seems evident is where most of the power savings are in the 295.The 295 has a DTSN (double-layer super twist nematic) LCD display. This is a passive matrix display which is commonly used in palm tops which run on alkaline batteries. Most laptops and higher end notebooks use a different type of LCD display which is known as active matrix or TFT. The passive matrix displays are lower in power than the active matrix displays. However, the active matrix displays are generally brighter and have a wider viewing angle. The Cold Cathode Florescent Lamp (CCFL) backlighting used on the 295 has been standard in virtually all notebooks and laptops for years. Its also used as the backlight in both the 430 and 530 panel mount units from Garmin.
The one thing you didnt mention is that there’s an alternative to alkaline batteries for high drain applications. Eveready has a lithium-based AA size battery with a nominal 1.5volt discharge voltage. It uses a Lithium/Iron Disulfide chemistry to achieve this voltage versus the more common 3 volts of most other Lithium chemistries.
Its called the L91 (vs. the E91 alkaline) and has a capacity thats twice that of alkaline AA cells. It also costs about twice as much so the cost per hour would be about the same but at least you wouldnt need to keep as many spare batteries around.
They have a much flatter voltage discharge curve than alkaline. They also weigh about half as much as alkaline which may help the roll over like a dead bug problem you mentioned with the 295.
I have been using these batteries for several years in critical applications such as my ANR headset and handheld. They have become easy to find recently and outlets like Home Depot carry them.
Greg Wroclawski
Kinnelon, New Jersey
When we update the chart again, we’ll include screen resolution. However, what you neglect to note in your letter is this: In cockpit conditions, the differences in resolution sometimes become moot.
As we reported in the April issue, the Garmin 530s TFT screen is far superior to the 430s DSTN in room light. In the cockpit, the difference is negligible.
Peltor Kudos
About five years ago, based on an Aviation Consumer report, I purchased two Peltor 7004 headsets. Recently I purchased another 7004 and an ANR Stratosphere.
Last week the plastic piece that attaches the boom to the earcup broke on one of the original 7004s. I called Peltor and spoke to Don Peyton. He was quick, courteous and a pleasure to deal with. A scant two days later, I received not one, but two replacement pieces by mail, all at no charge.
Thats service.
Bob Reed
Via e-mail
Di Blasi Replies
This letter is in response to the review of the Di Blasi Folding Motorbike, which was published in the January 2000 issue of Aviation Consumer. We were disappointed to read that Mr. Wilkinson did not have many favorable things to say about this product. But we were surprised to discover the review was for a product model which has not been sold since the fall of 1997. Why would you print a review in 2000, which was written in 1996, without a follow-up to the manufacturer four years later?
While we don’t feel it is worthwhile to go through each comment Mr. Wilkinson makes, since he is referring to a model no longer being sold, we are disturbed by his reference to the newer model as if he had tested it and as if he had spoken with a Di Blasi representative, which to our knowledge he did not. Had you or your writer followed up with Di Blasi, you would have learned that our new model, the Di Blasi Express, was designed to improve upon the older model.
While the general look of the Express appears similar, only few components of the older model are still used, such as the engine, tires, seat, shocks and locking device. Everything else was completely redesigned with respect to function and weight reduction.
In fact, when a customer has the opportunity to lift the new and then the old model, the noticeable difference gives the impression that the old one is bolted to the floor. We certainly promote the Di Blasi Express improvements as discernible from the earlier model that Mr. Wilkinson tested. In addition, Di Blasi customers have often commented on the improvements including lighter weight, steadier handling, quicker folding and improved workmanship and reliability. So we don’t understand how Mr. Wilkinson can write, But basically, the company concedes these improvements arent radical or perhaps even noticeable by the average customer.
We are sorry that Mr. Wilkinsons airplane design made it difficult to load and unload the Di Blasi. We acknowledge that some designs make loading easier than others. That is not the fault of Di Blasi.
One last point which I can personally attest does not measure up is Mr. Wilkinsons description of the perfect Di Blasi user. In the summer of 1994 a friend and I (two guys whose weight totaled approximately 450 pounds) flew in my newly built Wheeler Express with two bikes and camping gear from Oshkosh to Yellowstone Park, then on to California.
While in Yellowstone, we rode all over, with the longest ride being a day trip of 140 miles. In fact, it was experiences such as this which inspired me to become the North American distributor a year later.
Are you willing to be fair and print this letter in your publication? Mr. Wilkinson, are you willing to test-drive the Express?
Hardy Huber
Di Blasi of America, Inc.
We should point out that the article clearly made note of the fact that the model we tested has since been supplanted by a new model thats a bit lighter. (Its still 75 pounds fully fueled and ready to go.)
Further, we called Di Blasi to discuss the improvements before publishing the article. When asked if these improvements materially changed handling and operability, we told they were incremental changes.
Cheap Jets
I am looking at the S-26 from Safire Aircraft, which might make an interesting story for you. They claim to be able to produce a 330-knot, 1400-mile range, six-place, twin turbofan for $800,000. I am considering sending them a refundable deposit to hold a position but I would feel better about doing so if I had some independent information regarding the firm and the likelihood that theyll be able to deliver.
Do you know anything about the firm or the project? Do you think it would be good material for an article? They have a web site and I understand they now have quite a few deposits. If they can produce this airplane with low acquisition and operating costs, I will trade my Cessna 414A for an S-26.
Dale C. Eisenman
Hilton Head Island, South Carolina
Whether these guys can produce this airplane at the stated price may be the question of the new decade. Keep this in mind: Every new aircraft introduced during the past decade proposed a selling price lower than the final price. Cirrus, for example, proposed an initial price in 1994 of $130,000 with basic IFR equipment. Currently, it gives the basic price as $183,300 but we suspect the typical invoice is closer to $220,000.
Applying the same price escalation logic to the Safire, the true price is nearer $1.3 million, which strikes us as more realistic and still a good deal. Another proposed jet, the Eclipse (pictured above) is being pitched to the same market at a similar price.
FADEC Notes
The FADEC system article (March 2000) was excellent. The question I would ask prior to owning a FADEC aircraft relates to total power-plant system reliability compared to what I have today. My background is 36 years designing automotive electrical systems, including microprocessor engine controls. I also own a 1981 Skylane. I would ask to review the System Failure Mode and Effects Analysis (FMEA), a document sure to exist at Continental. This analysis would reveal the details of design redundancy to comprehend the individual component failures and their resultant impact on total system failure. It would also reveal the system designs implemented to comprehend ongoing redundancy verification.
The electrical system of dual magnetos and plugs was designed as it is because electrical system components fail, and this was the best method known to protect against total engine failure.
The FADEC system, unlike dual-magnetos, relies on an electrical system functioning at some level in the aircraft. The system FMEA would reveal in detail the design as it relates to failures of the aircraft electrical system and the interfaces to the FADEC system.
Some of these details may be outside of Continentals control since the aircraft electrical system is usually the sphere of the airframe manufacturer. Electrical components do fail and wiring systems are most prone to failure.
Items such as opens, faults, terminal back-outs, poor connector attachment and disconnects, corrosion, etc. can bring down an otherwise functioning system. Its always beyond the time and economic ability of the OEM to test the total system for all the potential failures; this is why an FMEA is performed.
System engineers then review the system FMEA and designs are changed until acceptable failure goals are achieved. My experience indicates that even after all this effort, complex systems can still fail. Interfaces between subsystems i.e. (FADEC and Aircraft Power/Ground) where multiple ownership exists are especially vulnerable and require added attention.
Art Sundeen
Lansing , Michigan
