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NexGen Flight Simulator: Hacking the Navigation Computer Display June 6, 2013

Posted by phoenixcomm in 16 Segment driver, Aircraft, Arduino, CP-1252/ASN-128, DIY Aircraft Cockpit, Embedded CPU's, Ethernet, Flight Simulation, Hardware, Indicator Lamps, Multi Function Display, ps2 keybaord, Semiconductors.
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CP-1252This is the CP-1252/ASN-128 Navigation Computer Display.  The NCD was originally designed for Doppler  navigation, but will work in my application. I have reprinted the Analysis of this from my WordPress Blog (22Apr2011)

The Analysis:  The NCD is comprised of 4 groups: Display, Keyboard, Rotary Switches, and Thumb Wheel Switches.  The Display is comprised of 4 16-segment and 13 7-segment PinLite lamps, and two LED’s.  The keyboard is comprised of a 10 key number pad and 4 special keys, it also encodes A-Z. There are two rotary switches, and two thumbwheel switches as well. I also found a users guide, TM-1-1520-238-10 pages 3-34 through 3-46 on the web.

In it’s dim past it had been converted to a flight sim, and the only thing left whrere: the display, switches, light plate, and lots of wire. Each component, had each of their connection(s) brought out in to a header.

The Plan: As it is almost impossible to find a 16-segment display driver, but I really found two parts MAX6954 (SPI and QSPI interface), and MAX6955 (I2C interface). Both devices have the same programing model and have a I/O expander which could handle the keyboard. I have chosen to use the I2C interface. I have broken down the NCD into the following sub-units:

  • Two MAX6955AAX+ :
    • one will handle the 4 16-segment displays.
    • one will handle the 13 7-segment displays.
  • The keyboard will be interfaced via a standard Ps2 keyboard encoder that will be harvested from an old ps2 keyboard.
  • I will also need 2 bytes of I/O as well:
    • 1 byte of output to handle the two rotary switches, via two priority encoders (74LS148).
    • 1 byte for both thumbwheel switches (they are encoded to 4 bit BCD).
  • And lastly I need a USB interface to talk back to the IOP (IO Processor)

I also need a embedded microprocessor, the NCD information does not need to be super fast, as in reality it is only a dumb terminal, so an Arduino should be able to keep up with everything, if there are speed issues I will most likely switch to a TI Stellaris Launchpad module.   The NCD is either taking keystrokes from the pilot, or updating the display. In the words of the Outer Limits “There is nothing wrong with your television. Do not attempt to adjust the picture. We are now in control of the transmission. We control the horizontal and the vertical”. In the scheme of things this unit will only be another end point on the IOP which is sending the key strokes or and knob turns to the simulation processor. And in turn the NCD in effect listens to the NavGroup via the IOP for present positiontime to go etc.

 Keep Tuned in More to Come!

NexGen Flight Simulator Blog Index


Driving those pesky indicators. December 30, 2011

Posted by phoenixcomm in Arduino, Boeing 707, Boeing 727, DIY Aircraft Cockpit, F-18, Flight Simulation, Indicator Lamps, Power Systems, Relay.
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Well here we are again, and I am having to drive multiple of voltages for my indicator lamps…. This can be a pain in the rear… Let me see I have  5 volts, 12 volts, 28 volts. Take your pick..

You have several choices:

  1. Do nothing, just buy lots of power supplies.
  2. Change out all the lights to one voltage. (big bucks)
  3. Something else maybe?

Me I’m out there anyway so I’m going with you guessed it: ‘C’.

The Analysis: First a little background…
Rule #1:  Computers Logic (TTL) does not like voltages over 5 volts dc.
So how do you drive a 28 volt lamp from a computer?  There are several ways..

  1. Relays..(ADVANTECH PCLD-785B with 24 relays) This card retails for $240.00. Or you can find them used for about $50.00 on ebay. This tends to be some what costly as you have to buy the boards and then a driver for them. It’s more than little kludgy with tons of wire screwed down, on barrier strips. But it does work and its bullet prof. But remember all those power supplies.
  2. HEX INVERTER BUFFERS/DRIVERS WITH OPEN-COLLECTOR HIGH-VOLTAGE OUTPUTS SN5406 and SN7406 have minimum breakdown voltages of 30 Volts DC. But when they fail it could put raw 28 volts on your computer! Ouch!
  3. Optoisolator I like a little 6 pin dip a TIL111 will handle 0 to 30volts DC with TTL inputs.  If  you want you can buy them at Digi-Key for about 18 cents each, and if you look around you can buy them cheaper else where.   Add a few parts for decoding and latch, you can drive all of your lamps.

So lets see 18 cents x 64 optoisolators is less then $12.00. This means that with just 16 cards you could drive 1024 lamps…  But wait a minute I said DC right? (Who said we had to drive the lamps with AC). Now that we have DC you can easily create a divider or regulator for you lamps from one 28 volt power supply.

What you can get away with on TV – Pam Am: Unscheduled Departure November 14, 2011

Posted by phoenixcomm in Boeing 707, Pan Am, TV.

I really watch too much TV, and this evening, in this episode of Pan Am, they have to land at Haiti to seek medical help. They decide to take off and restart the engines…..
Whoops! Good TV just hit reality! Most of the Boeing 707 didn’t have a APU installed (Saudi Arabian Airlines did). So the only way to start the engines was to have high pressure air, from a ground cart.
So how did they get the engines started after they landed and shut down???

Also while the plane was parked on the ramp they had cabin lights on. This comes from the generators on the engines, or from a ground cart (there is that pesky ground cart again).

Hey its only Television….

A Physics Lesson: or what you can get away with on television commercials. – part 2 November 6, 2011

Posted by phoenixcomm in Boeing 727, Flight Simulation, Nissan Frontier Commercial.
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Well here we go again….. I found another link to this on Yahoo Answers Is it possible to land a plane like this?

They got most of it wrong… First it’s NOT a DC-9, if you look under the wing there are no engines, and there is one engine in the rear under the rudder, this can only be one, plane the Boeing 727. The best answer was a U2, which has nothing to do with this problem. And then there was the answer about the other Internet video that is amusing but the poor driver should be dead.  And more there was another answer about a CH-53,  also nothing to do with it.  None of them got it right!

FYI… 727s are parked with their rear ramp down, to prevent the nose from rising into the air.

Newsgroups: sci.aeronautics.airliners
From: David L
Subject:A320, MD-80, 727
Date: 01 Dec 93 03:16:29 PSTIn a reply to the question as to why MD-80’s and 727s have their ventral stairs down on the ground: it keeps them from tipping over (tail down) should someone goof in loading them! In the AIAA “Cases Study in Aircraft Design: The Boeing 727”, Mark Gregoire relates a story about when the first 727-200 was delivered to National Airlines. “As it rolled to a stop near the National hanger, amid the expectant dignitaries, the pilot touched the brakes and the airplanes nose went down and then recoiled up and lifted the nose gear off the concrete approximately 6 to 8 inches.
The gasps in the crowd where hear 3,000 miles away in Seattle. Bill Clay put a team together and, armed with weight and balance data, toured the airlines outlining the entire spectrum of configuration control, ground handling, ballasting, and precautionary measures from sloping ramps to heavy snow loads on the tail. As far as we know, no 727-200 has ever sat on its tail and maybe we over reacted the National incident, but that’s why, you will nearly always see a 727 with with its rear airstairs down when parked.”
Newsgroups: sci.aeronautics.airliners
From: Terrell D (bcstec.ca.boeing.com)
Subject:Re: A320, MD-80, 727
Date: 28 Nov 93 16:39:03 PSTTypically it is to keep the airplane from tipping back on its tail. Rear engined airplanes have chronic problems with CG location empty. They have other chronic problems, but I won’t go into that. 🙂
The CG problem stems from having the CG of the empty airplane well aft of the CG of the payload (the passengers and baggage). When summed
together, the CG of the airplane system must be within a relatively small range defined by the stability and control requirements and tail power
available. The landing gear like to be pretty close to the CG of the loaded airplane in order to allow easy rotation at takeoff. So, when the
airplane is NOT loaded, the CG moves aft – very close to the main gear – and someone walking around in the back, or loading cargo into the aft
cargo compartment, can easily cause the airplane to tip back.

Multi-Function Display (MFD) System – Part 1 November 5, 2011

Posted by phoenixcomm in DIY Aircraft Cockpit, F-18, Flight Simulation, Multi Function Display, Video Interface.
Ok well I got my MFD, a few years back, and has been laying around collecting dust. It was a prototype made by Precision Imaging, which is now Precision Display Technologies. There part number is MPCDX-PROTO, which is for the F/A-18C/D.

The Analysis (1) The MFD is a 5″ x 5″ color, raster-scanned display, it has a RS170 video interface (BNC connectors) with sync on GREEN or separate/composite video sync.
(2) The MFD has 20 switches which looks like it goes to the DB-37 on the rear of the unit. That will be in another post.

The Plan Well first I need to build a new cable. Lucky I have extra cables, so I had a old Sun Monitor, DB13W3 to BNC, cable, and a VGA Cable. So I cut the DB13W3 connector off, and one of the VGA Connectors on the other cable. I hooked it up according to chart below.

2 X
3 X
X = Connection

Here is the first try with the MFD needing to be adjusted.

A Physics Lesson: or what you can get away with on television commercials. – part 1 October 22, 2011

Posted by phoenixcomm in Boeing 727, Flight Simulation, Nissan Frontier Commercial.
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I just saw a commercial the other day where this a Nissan Frontier pickup truck puts a Boeing 727 nose wheel in the bed. Ok. So ask first, what is the truck’s MAXIMUM PAYLOAD? The MVW is only 1500lbs.

So you ask; how is this possible?

Using weigh tables, a light Boeing 727 could land as low as 104 knots (119.5mph)[we think the truck would have problems getting up to speed, not to mention intercepting the jet and  then getting the nose gear and bed lined up], with no load, and flaps out.  A Boeing 727 has pair of 32×11.5, 12 ply tires weighing 61 lbs each plus the wheel axle, front steering gear for a not so small weight of 327lb .

Well you could ‘rig’ this by rear-loading the aircraft so you have one to several hundred pounds on the nose gear.
You will notice that the dust the truck kicks up after the truck and not in line with the truck tires.
Keep checking back where not done with this horse yet…..
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