Website improvements

[Warren B. MusselmanModerator]

I must stand up here and make a “Mea Culpa” style apology – in particular to Adrian, but to the all the other “altitude junkies”.

For years, there was very little choice in altimeters – Adept, Olsen, Perfectflight, Missileworks and a few other minor manufacturers. All of them reported altitude immediately and with little if any in the way of data beyond the beeps or blinks reported. At one time, I had a conversation with Jim Amos, manufacturer of Missileworks products, about why he didn’t add some of his very impressive flights to the altitude record database. His reply was in essence that regardless of whether he flew a production altimeter or not, there was always the potential issue of a conflict of interest in that he designed the altimeter, wrote the code and manufactured them and there was no way for anyone to know or for him to prove that it wasn’t a cherry-picked device – either with different code or hand-picked parts and so rather than put himself in that position, he completely recused himself from participating. That struck me as a most honorable position to take. When I’ve told that story, most fliers I spoke agreed with that position.

When Adrian first produced The Parrot, his original altimeter product, I was hugely impressed from a geek and technical perspective. In fact. I consider Adrian’s products to be far superior in terms of accuracy and precision than any other commercial altimeter. However, this led to quite a few discussions, some quite heated, that post-flight data reduction and analysis had no place in a contest that depended on the LCO at the flight table and 2 witnesses to immediately report the altitude on the flight card following the flight. The Parrot required off-line data reduction and analysis to report the altitude. In addition, its barometric altitude was based on a much-needed update to the so-called “Standard Atmospheric Model” used by every other commercial altimeter on the market at the time. Quite a few fliers felt that this was an Apples-to-Oranges sort of comparison and without significant data from flights using both his and other manufacturer’s altimeters, we couldn’t decide which would the more accurate or whether his approach to processing barometric data would result in an competitive advantage. In fact, in quite a few early flights, we were seeing altitudes substantially higher than either Rocksim predicted or similar birds achieved using other altimeters.

Prior to this point in time, most of us altitude junkies had a fairly even view of altimeters and that an altitude reported by a Missileworks, Perfectflight, Adept, Olsen, etc. altimeter would all be in the same ballpark and we were playing on what appeared to be a level playing field. The Parrot and then The Raven changed that. From an engineering and scientific perspective, I will gladly admit that I consider Adrian’s products technically superior and in all likelihood report a more accurate AGL altitude than the others. However, we come back to the Apples and Oranges dispute. Is it fair to compare altitudes determined in one fashion (based on the Standard Model) with altitudes based on a different model? Is it fair to compare the quick and dirty in flight altitudes reported by the bulk of altimeters on the market to altitudes that have been determined by post-flight data reduction, smoothing, etc.?

Then enter TRA – the national organization – and their complete reorganization of their own altitude records rules and methodology and add on top of that their requirement that altitudes above 25K’ AGL would need to be determined by post-flight analysis of RAW GPS data. In case you don’t know, that isn’t the straight NMEA strings all GPS chips produce but the underlying data behind it involving detailed timing analysis of the signals from multiple GPS satellites. While TRA may have or acquire the technology to do that for a world altitude record, it was way beyond my capabilities as far as maintaining the records database. Beyond that, my ongoing discussions with many of the altitude junkies were far from a consensus and the discussion heated up to the point where several folks, myself included, have completely backed away from competing on a playing field that we could not agree was level.

Now some folks may feel that I over-reacted by just shutting down the contest – they are very likely correct. I was just sick of dealing with differences of opinion and what was turning into rather heated discussions in an area where there had previously been only consensus. From my perspective, this club is a place to encourage and support community amongst the participants in this esoteric hobby of ours and given that I saw several close friends back away from the contest and the hobby because of these disputes, I felt that to continue it given our limitations, wasn’t a good thing for the club. One result was I resigned as Contest Director last year, dumping it on Chad Moore. Another result is I and several flyers I know (to remain anonymous) just stopped playing the game. It was my feeling that until some kind of consensus evolved in the club and in the hobby as a whole, the whole thing should be placed on hold.

In that act, I know I’ve done a disservice to the many altitude junkies who have put great time and effort into their projects and making their flights. For this I apologize, I just couldn’t come up with a path that both addressed their needs and that helped to form consensus and comity amongst club members.

It is my hope that Adrian, Bdale, Chad and the rest of the executive committee, perhaps with guidance from the TRA Altitude Records Committee can thrash this whole thing out and that the club can have an open discussion at the Annual Meeting so that a consensus can be formed as to what is fair and what constitutes a level playing field.

Again, Mea Maximum Culpa from me to the club as a whole and to those who my decision has affected.

[Warren B. MusselmanModerator]

Oh yeah, THE #1 thing I’d love to see is a “Like” button on forum posts.

[AdrianParticipant]

Apology accepted, Warren. I know you have been doing your best on this and your heart is in the right place. There is one assertion that you are making that is incorrect, however, that I think has been at the root of the controversy. I’m sorry that I have probably contributed to the misunderstanding, so let me try to clear this one up:

The fact is that every Parrot used to apply for a record, and every Raven, period, uses the same standard atmosphere model that every other altimeter does. There is no difference in technique that would cause Raven or Parrot altimeters to read higher than any other altimeter. It’s a fact supported by the evidence that for every flight where a Raven reads higher than another brand of altimeter, I can show you another flight where it reads lower. For example, on my L record flight in October, which had a Raven, a Telemetrum, and a Beeline GPS, the Raven read lower than the GPS or the Telemetrum’s baro sensor.

Where I think this misunderstanding got started was from way back when I first started making Parrots in 2007. At that time, I didn’t have a reference pressure gauge to do the calibrations with. I did have a car and USGS elevation maps, however, so I drove a Parrot on I-70 to Silverthorne, and recorded data along the way so that I could calibrate that altimeter’s altitude readings. I then used that unit to calibrate other altimeters in my vacuum chamber. What I didn’t realize until a few months later was that that method would produce somewhat higher altitude readings than if I had calibrated against a reference pressure gauge and then converted pressure to altitude using the standard atmosphere model. The standard atmosphere model under-predicts altitude when the air temperature is warmer than 39F at 5000 feet elevation, which included when I did my test drive. Once I understood this issue, I bought a reference pressure gauge and from then on, I calibrated against that standard so that the readings would be equivalent to all other baro-based altimeters. That handful of initial units that read a little higher (and more comparable to what a GPS unit would) were never used for a record application by me, or as far as I know, by anyone else.

Since then I made hundreds of Parrot V2 altimeters that use the standard atmosphere model, and now over 1200 Raven altimeters. All of the Raven altimeters have the additional benefit that the whole pressure measurement system is calibrated at the chip factory, not by me, and is extremely accurate over a wide range of sensor temperatures. There would be no point in cherry-picking a Raven, even if I wanted to, because they are all the same. The current Tripoli rules state that if you want to set a Tripoli record, you have to use a Raven altimeter that comes from the group of 20 Ravens that Tripoli bought for that purpose. John Beans, who makes the Jolly Logic altimeters, told me recently that when he tests the altimeters he makes for accuracy, he flies them on a sled next to a Raven altimeter.

All of the record applications I mentioned before that I would like to see on the list, were made using a Raven altimeter. Thanks for listening.

[Warren B. MusselmanModerator]

Well then Adrian, I owe you an even larger apology. From early discussions you and I had when you were developing the Parrot, I got the impression you were working to come up with a better model (given the limits of the SAM) and were using a NIST-traceable pressure chamber to test and calibrate.

I won’t burden the forum with further blatherings – just know that I deeply apologize for my own errant assumptions and the impact that they have had on my thinking over the last few years.

I do propose that we have an open discussion on this topic at the annual meeting if we can get enough of the interested parties together for the discussion. I will gladly re-enable the altitude contest code and we can move forward.

Again, my sincere apologies.

W

[AdrianParticipant]

Thanks, Warren, for accepting the correction of this misunderstanding with such grace. No hard feeling here.

[Steve Huntwork]

I was very worried about opening up that can of worms, but it looks like it did some good. Sometimes having someone new and totally impartial can be helpful.

Thanks Warren for not chewing me out too much… LOL

[Warren B. MusselmanModerator]

Why should I chew you out? Energy and drive are what I’ve been trying to find…

[Bruce R. Schaefer]

Shunt1, Warren is a very good mentor in this area. He’s carried us this far and your main source. I’ve already noticed the improvements you’ve made. Warren’s the mother hen right now, soon you will be. Thanks for your help, Shunt1!

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