Airspeed in the datalog output

[Etienne]

Hi

A quick question on the airspeed output in the datalog stream: is it TAS or IAS? If it's IAS, is there any way to calculate the TAS using the the other data in the stream?

Thanks
Etienne
South Africa

 

[dynonsupport]

Etienne,

The Airspeed in our stream is IAS. Unfortunatley, you can't calculate TAS with what is in the stream because we don't give you OAT in that stream. If you can get OAT from somewhere else you can do it.

 

[Etienne]

That's a pity... Is there any way to change that? I've been reading through a whole bunch of the recent posts and I've come across quite a few requests for changes to the datalog, the most recent is to include winds aloft and a pass-through from the gps. Is it not time to create a version 2 of the protocol which would include all of these enhancements? Obviously to be backward compatible it would be necessary to have a user-selectable option to choose which version is streamed out...

What is the possibility of this happening? Maybe run a poll for a couple of weeks to see what other information people would want?

A few suggestions:
OAT, higher resolution heading (0.1 deg, like pitch and roll), current QNH...

Why is 1st Sept taking so long to get here? *drum fingers in anticipation*

 

[dynonsupport]

There are some technical issues on the backend that prevent us from streaming out absolutely everything that the EFIS can display. Though we could add some things to the serial stream, there are no current plans on our development schedule to do so.

 

[cguarino]

Why don't ya'll take a poll. Your customers should drive the requirements. We want to buy what we want not what you want me to buy. That is unless they are the the same thing. Thanks.

 

[Etienne]

I tried adding a poll here: http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1155104251/0 but it didn't appear to work. Anyway, that thread is to ask the question what people want to see in the datastream, as the topic of this thread is rather specific...

Regarding the feasibility of adding a few fields to the stream, I can understand that not everything is available, although to be truely useful there are 2 fields that are very necessary: oat and qnh... With these two, you can work out density altitude and TAS, which allows anyone to externally calculate winds aloft and pretty much everything else I was asking about.

A change to the dataformat is a change to the dataformat (i.e. a small change will break as much as a big change), so if one day you do decide to modify it, then you may as well go large and change everything, but leave it up to the user to decide if (s)he wants to use the old or the new format. My 2c.

 

[bertrand]

I think that TAS instead of IAS would be better . In case of no OAT measurement (no sensor or no T° entered on panel) , the TAS should be replaced by the IAS.

I saw questions about the precision of the G's measures . One more digit sould be better assuming that the sensor is capable to give this precision.I'am also questionning myself about the sensibility in frequency of the sensor . I think that it's not 1/64 of a second ...based on recordings I've done ( measuring of fly in turbulence conditions) .

The proposal of various version of data output is interesting as it enable people to keep their datalogging hardware and software unchanged .

Cheers

Bertrand

 

[waiter]

OAT is available in the EMS-10 datastream.

As far as adding new fields to the datastream, its always a good idea when creating the original datastream to add "SPARES" to the stream. On the other hand, its always been my experience that the spares always seem to be the wrong format for what I want to add at a later date, URGH.

Anyway, if additional fields are added, please add them at the end of the currently accepted record format, as this makes it easiest to do upward compatibility in any software that exist.

If new fields are added, I'll update Waiters Flight Data Recorder to ensure its compatable with any stream that Dynon puts out.

Waiter

 

[meljordan]

As no company has unlimited resources, any work done on one function will necessarily reduce the work done on another function. I for one would rather have the Dynon folks focus their time on adding additional functions and capabilities to their instruments. With over 500 flight hours on my Dynon EFIS and 300 hours on my EMS, I have yet to see any need for datalogging functions. I know that others my disagree and want to have these sort of detailed datastreams so they can roll there own functions or print out flight path and engine charts, but I would rather see Dynon spend engineering resources on increase functionality. Data logging has no value for me, where as an HSI display would be very useful. I can think of a number of additional functions with a much higher priority on my list than datalogging.


Mel Jordan
Tucson

 

[dynonsupport]

At this point we don't have any plans to change our output stream since we don't have the engineering resources to do it. We're always happy to listen to our customers, so please keep the comments coming, and we'll keep it on the list, but we're busy working on other things right now.

Dynon doesn't run an operating system on a PC processor like many other companies do, so adding things to our streams, changing data rates, or making the output selectable isn't a simple task. This archetecture gives us the reliability and fast boot times that you have come to expect from us though. The stream out from the EFIS comes from a real-time, stand-alone microprocessor that acts as our ADAHRS unit, so changing this is a pretty big task that carries a risk with it of causing a bug in the ADAHRS. As far as we know, we're the only company that outputs any data at all in a published format, so we're pretty ahead of the game here.

Also remember that we currently use the output of the EFIS to create the copy of the screen on the EMS, so we need to change both the parser in the EMS as well as the data output in the EFIS. It's a lot of work.

Once we have full DSAB out and the stream isn't used by us anymore, we might consider adding stuff. Keep letting us know what you want and hopefully we'll get to it some day, but we aren't making any promises today. Maybe someday we'll even be able to output in standard ARINC 429 format and you'll just be able to pull that if you want it.

One thing I'd personally be very interested in is what our customers are doing with all of this data. What kind of analysis do you use it for? What kind of displays are you designing? It may be better for our customers to put some of this functionality right in the unit rather than having you design it outside.

 

[Chasspin]

I have been using my Viggen as a surrogate unmanned aircraft to test sensors for the Unversity of Washington. The airplane is instrumented with temp and humdity sensors, two GPSs, the EFIS D-10A, Engine monitor, flight data recorder, sensor system, a modified UAV autopilot and data links. After the the first set of test flights we published the results in several scientific journals. I sent a copy of one of the papers to Jillian a while back. I can send you another copy if you like. The pubs are listed below. I also presented the papers at a UAV conference in Australia last November. So I really use the data research puposes and would like to be involved if you guys ever change the data stream..

Publications & Papers using the D-10 data
C. B. Spinelli, C. E. Furlong, S.Yee, T. Chinowsky, A. Naimushin, S. D. Soelberg, T. Mann, R. C. Stevens, P. Kauffman, Airborne analyte detection
with an aircraft-adapted surface plasmon resonance sensor system, Sensors and Actuators B (Chemical) January (2004).
S. D. Soelberg, T. Chinowsky, G. Geiss, C. B. Spinelli, R. C. Stevens, S. Near, P. Kauffman, S. Yee and C.E. Furlong, A surface plasmon resonance
(SPR)–based sensor system for real-time monitoring of analytes that range in size from small organics to whole cells”, 7th International
Symposium for Environmental Biotechnology Chicago, June 2004
T. Chinowsky, C. B. Spinelli, C. E. Furlong, S.Yee, A. Naimushin, S. D. Soelberg, P. Kauffman, Airborne surface plasmon resonance biosensing,
Environmental Monitoring and Remediation III, Proceedings of SPIE Vol. 5270 August 2004

Charlie

 

[khorton]

I will be recording data from a number of avionics boxes (D10A, EIS 4000 engine monitor, GNS 430 GPS) plus from an event marker.  I will use this data during my flight test program, to help determine aircraft performance, and as information when reviewing the results of handling testing.  For aircraft performance, I am interested in pressure altitude.  I will put the altimeter setting to 29.92 before starting any performance tests, and put it back to the local setting later.  But it would be much nicer if the data stream included pressure altitude, or the altimeter setting (so I could correct the barometric altitude to pressure altitude during the data analysis).  An extra decimal place resolution on the vertical g would be nice when looking at the data from handling flight testing.  64 Hz is more data than I need for flight testing.  I have set up my data recording scripts to pick off data at a selectable rate.

Later, I may use the EFIS as a sensor for the pitch axis in an autopilot.  I would use the air data, pitch and vertical g as inputs to the autopilot control laws.

 

[13brv3]

The EFIS data will be useful for initial flight testing, and for documenting the effect of any modifications later on. What's more valuable to me is the EMS data.

I have a friend with a JPI engine monitor in his RV-8, and JPI has a great datalogging system built into their monitor. In the last couple years, this guy has had two different engine problems that were diagnosed by looking at the data.

In one case, the engine ran rough for 20-30 seconds during a flight, then went back to normal. He was able to see that EGT dropped on two cylinders, which led him to the only thing common to both cylinders, an electronic ignition coil. More recently, it started intermittently running rough again, and he was able to see that it was only one cylinder this time. The problem is a sticking exhaust valve.

Without datalogging, he would have spent far more time diagnosing these issues, including several potentially risky flights to verify whether the problem was actually resolved. EMS datalogging is a great feature, but not something you'll use every flight. I think of it like a parachute. Most of the time it's excess baggage, but when you need it, you NEED it.

Cheers,
Rusty (Antilog RS232 datalogger working perfectly)

 

[dynonsupport]

We output pressure altitude as the signal to the transponder, so you can pick this up easily with an additional serial port.

 

[khorton]

We output pressure altitude as the signal to the transponder, so you can pick this up easily with an additional serial port.

Ohh.  Great.  I'm on the road right now, so I can't try this out.  Is the data format obvious once you look at the raw serial data, or will I need to find the format somewhere?  What is the baud rate?  What is the resolution of the pressure altitude?

Time to buy another four port USB-serial converter, I guess.

Thanks for the very useful info.

 

[dynonsupport]

We output four different formats to accommodate the various transponder input requirements. You can choose which format your EFIS outputs. The procedure to do this and the 4 data formats/baud rates can be found on pages 11 & 12 of Rev C of the EFIS-D10A Installation Guide found here:

http://dynonavionics.com/downloads/Install_Guides/100341_-_Rev_C_-_EFIS-D10A_Installation_Guide.pdf

 

[Etienne]

Ok, well it's a start

I'm guessing you guys are already busy pushing all-nighters for the HSI - maybe once the pressure's off you'll have a chance to look at it... Here's hoping

 

[dynonsupport]

The resolution of the serial transponder output is 10 feet (in format 4 for sure, I think also in other formats).

 

[Etienne]

*bump*

Right, now that the new firmware is out in the wild, having been set free from the confines of the developers and beta-testers ;D , would it be possible to re-look at the suggestions given here?

Pretty please?

 

[dynonsupport]

We're always looking at the suggestions here and putting them on the wish list for future firmware. It's a BIG list!

While we just released firmware, we have a lot of other things going on here as well, so we're not sure when the next update will be or what will be included. At this point, we still don't have bi-directional DSAB, and I think it will be in an update after that one before we consider changing the data output stream on the EFIS.