DM41L at work

[walter b]

(01-06-2016 06:54 AM)Paul Dale Wrote:  I don't know if commercial airliners reach the altitude limit or not, I doubt they reach the velocity limit.

a) I don't know either. How high is it?
b) Not voluntarily.

d:-)

[Paul Dale]

I don't remember height limit, just that there is an artificial limit.

The velocity limit is supersonic from memory which airliners can never reach, at least not without crashing.


- Pauli

[Geoff Quickfall]

okay,

lots of responses and I will ignore the language associated ones. English is my second language, I don't have a first language unfortunately.

Paul and HrastProgrammer

1. I had a 1996 Magellan GPS which i suctioned cupped to the rear cockpit windshield of the 737-200. The aircraft had no GPS capability. It cruised up to 36000 at Mach .74. The GPS functioned perfectly although it was not licensed for aviation use. It was fun to play with at the time. The reason it had to be on the rear cockpit window was that the windows are two panes sandwiching a liquid vinyl inside heated by clear aluminum sheeting which keeps the vinyl and window warm. This creates a barrier to radio reception. The main front and large side windows are heated on the 737 and interfered with the handheld GPS reception. Another problem is when it is stuck to a window you can only receive from the satellites on that side of the aircraft.
2. the DC10! that brings back memories but substitute the HP 48 with my 41CX running the same programs the DM 41L is shown to have loaded plus a few more like critical point, point of no return, optimum altitude, anti skid inop, full lido flight plan with printer capability plus a few others.
   

Walter, may be impractical but still usable. I wrote these for the 41CL in 1986 while on the DC-10. The largest on board computer on that airplane had 4K worth of memory. The 41CX saved a lot of time!

For a thorough explanation of these programs including formulae and etc. see my presentation for HHC2013: HP calculators in aviation

• The first three routines starting from the left of the user keyboard reference: load waypoints; great circle; intermediate latitude are calculated by the on board flight management computers so they are redundant, EXCEPT as an independent calculation free of any bugs that may be present in the vendors data base. Also, when in the middle of the Atlantic with an air traffic control route change, the routines provide a crosscheck to the on board flight computers. The crosscheck is usually provided by the hardcopy flight plan but when the route changes the flight plan does not reflect the new true track and great circle distance needed for crosschecking. The intermediate latitude check provides an independent crosscheck to the onboard systems also. At my airline it is standard procedure to plot on the chart a point 2 degrees after each waypoint and check the latitude.
• Temperature Corrections: The onboard altimeters do not correct for temperatures below 0'C and significant altitude errors occur the greater the temperature is below 0. Some aircraft have this function built into the altimeter where the current outside air temperature is dialed in. B777 do not nor did the DC 10, 767, and 737 that I flew. Hence, instead of using a chart with interpolation required I use the actual formula to produce the actual altitudes. See my 2013 presentation for a more detailed description including the formula used.
• Fuel in Tank: Ever since the Gimli (click on GIMLI for an article) incident checking the fuel placed on board by the fueler in litres converted to Kgs and comparing that to the gauges in Kgs the Fuel in Tank program is very useful. Either that or a pad, a calculator and a pen.
• Break schedules: for long haul flights, well there is an APP for that but not as flexible as my program written in 1986 and still useful today. Usually the 41CX or the 42S and now the printing Woodstocks along with the IR printer accompany me and hard copies of the breaks are produced. Can't get the APP to print!
• world time program: the clock on board is GMT, the onboard computer tells us the arrival time in GMT, this program prompts for the destination airport and gives you the time of day, day and date.
• flight time program: great routine and uses extended memory. once started provides a countdown timer, chronograph, and calculates the current time, day and date plus the estimated arrival time day and date. very useful when you are walking the cabin during the flight and someone asks.
• set gmt and alarm: the calc is always in GMT so when I use it as an alarm clock in different time zones this program will calculate the correct time given the airport three letter code and set the alarm.
  

So while one can get by without the calculator and the routines, life sure is easier with it. So I disagree with your friends analysis of 'impractical'.

For all those commenting on stuff in the flight deck not locked down. These photos were for demonstration purposes here during a smooth flight. The calcs reside in my flight bag. I have yet to be hit by flying HPs over the last 40 years of flying!

Cheers and happy new year!

Geoff

p.s. I am getting used to the keyboard layout even though it may violate the sensibilities of some

[Didier Lachieze]

(01-06-2016 08:09 AM)Paul Dale Wrote:  The velocity limit is supersonic from memory which airliners can never reach, at least not without crashing.

Well, there was one supersonic airliner some years ago, and there was already a 41 inside: Concorde's pocket calculator HP-41CV. For details about the calculator usage on the Concorde see here and here.

[Geoff Quickfall]

Pauli,

SST was supersonic and a Canadian Pacific DC 8 on a test flight ten years before the SST was also taken supersonic (greater then Mach 1) cp dc8 supersonic link

Cheers

[HrastProgrammer]

(01-06-2016 08:26 AM)Geoff Quickfall Wrote:  [*]the DC10! that brings back memories but substitute the HP 48 with my 41CX running the same programs the DM 41L is shown to have loaded plus a few more like critical point, point of no return, optimum altitude, anti skid inop, full lido flight plan with printer capability plus a few others.

That HP-48GX has been running my HP-41X emulator used to execute various HP-41 software, including the ASTRONAV which Antoine has been developing, enhancing and updating for 30+ years ...

[Geoff Quickfall]

(01-06-2016 08:45 AM)Didier Lachieze Wrote:  

(01-06-2016 08:09 AM)Paul Dale Wrote:  The velocity limit is supersonic from memory which airliners can never reach, at least not without crashing.

Well, there was one supersonic airliner some years ago, and there was already a 41 inside: Concorde's pocket calculator HP-41CV. For details about the calculator usage on the Concorde see here and here.

interesting links, thanks Didier!

[Harald]

(01-06-2016 06:54 AM)Paul Dale Wrote:  I don't remember the specific values, but commercial GPS units have an altitude and a velocity limit beyond which they won't produce a position. I don't know if commercial airliners reach the altitude limit or not, I doubt they reach the velocity limit.


- Pauli

I played with my tomtom satnav on various flights. I used it to record gps tracks. It had no problem with speed and altitude. It did get confused trying to recalculate the route though, jumping from road to road and recalculating all the time. So I had to stop navigation and everything was fine.

[Sanjeev Visvanatha]

(01-06-2016 08:26 AM)Geoff Quickfall Wrote:  For all those commenting on stuff in the flight deck not locked down. These photos were for demonstration purposes here during a smooth flight. The calcs reside in my flight bag. I have yet to be hit by flying HPs over the last 40 years of flying!

I was fairly certain of this! I still am waiting for the day I board Air Canada and hear that you are the pilot of my flight!

[Alex Liggett]

(01-06-2016 08:09 AM)Paul Dale Wrote:  I don't remember height limit, just that there is an artificial limit.

The velocity limit is supersonic from memory which airliners can never reach, at least not without crashing.


- Pauli

Interesting. According to the ever-reliable Wikipedia the limit is 1000kts at an altitude of 18km or more, to prevent the use of C/A code receivers in ballistic missiles.

[Geoff Quickfall]

Best I have done is 728kts (1348 km/hour) on the B777 at Mach .86 but I didn't have the portable running. The onboard GPS (all three) had us at 728kts and they are commercially available.

We were at FL330 in the POLAR jet stream from Beijing to Vancouver with a 190 knot tail wind. Smooth as glass.

Geoff

Sanjeev, if you or anyone else hears my name, send up a business card or note to the flight deck via a flight attendant.

[Guenter Schink]

(01-07-2016 08:29 PM)Geoff Quickfall Wrote:  Best I have done is 728kts (1348 km/hour) on the B777 at Mach .86 but I didn't have the portable running. The onboard GPS (all three) had us at 728kts and they are commercially available.

We were at FL330 in the POLAR jet stream from Beijing to Vancouver with a 190 knot tail wind. Smooth as glass.

Geoff

Sanjeev, if you or anyone else hears my name, send up a business card or note to the flight deck via a flight attendant.

Some competition? My fastest was 288kts tailwind overhead Shefferville, resulting in about 760kts (1407Km/h) at Mach 0.82 on the old horse B707. From Winnipeg to Cologne, most probably at FL 370. Sorry no GPS in the late 70's. Speed cross checked with INS and VORTAC. It wasn't smooth at all, more like participating in a Rodeo at Calgary.

Günter

PS: Vancouver, Geoff?

[Geoff Quickfall]

You win,

Working on a second tier list as the four big conference hotels were prohibitively expensive.

Not to worry, also remember, the dollar is 70 cents to the US dollar, so big savings there.

Will have updates to the committee soon.

Cheers.

[Guenter Schink]

(01-08-2016 12:15 AM)Geoff Quickfall Wrote:  You win,

Cheers.

Well, that's not the final word. You have some years to see higher speeds, while I'm done already

Captain Günter

[Soroban]

Hi Geoff!

I really like your dm41l in situation.

I am also a pilot, and I would like to know where I can get the program you use in your plane if possible.

Thy

Adrien

[IVIAX]

(01-19-2016 08:43 PM)Soroban Wrote:  Hi Geoff!

I really like your dm41l in situation.

I am also a pilot, and I would like to know where I can get the program you use in your plane if possible.

Thy

Adrien

Same goes for me.
I found some options, i.e. the aviation module for the HP41 and a 41 emulator for the iphone. But I would prefer a calculator based solution for quick calculations, as mobiles are not allowed in all enviroments (military pilot).
I already own a wp34s which supports 42s programms.
Is it possible, to port the aviation module programs to a 42s format?

Best regards,

Max

[Maximilian Hohmann]

Hello!

(01-06-2016 06:54 AM)Paul Dale Wrote:  I don't know if commercial airliners reach the altitude limit or not, I doubt they reach the velocity limit.

I don't fly airliners but business jets. "Mine" can fly at 45.000ft which is higher than most airliners can reach, because of cabin pressurisation limits: It is a lot easier to build a light pressure vessel in small size than large. I have not come across a GPS unit, be it dedicated aviation, automotive, smartphone or tablet, which can not handle this elevation and the associated speeds.

Regards
Max

[grsbanks]

This post was linked to in a Facebook group that I recently joined.

OK, it's from 2 years ago but I thought I'd just comment on a couple of things:

(01-04-2016 01:02 PM)Geoff Quickfall Wrote:  Not so plus:

1 CAT 4,5 and 6 scroll way too fast, will be fixed in updated firmware.
2 PSE way too fast in 48mHz setting, will be fixed in updated firmware.
3 124 registers on extended instead of full 600, may be fixed in future firmware.

1 was fixed in firmware V25.

2 was fixed in firmware V24.

3 was half fixed in V25. There just isn't enough RAM on the LPC1115 chip used in the DM41(L) to provide the full 600 registers of X-Mem. However, by reorganising various parts of the firmware it has been possible to add one X-Mem module's worth of extended memory so V25 gives you 362 registers of it instead of the original 124 that are provided with the X-Func module.