I'm researching the amount of solar energy available to photovoltaic cells placed at various locations on an aircraft's body. To calculate the angle of incidence of the sunlight on different parts of the plane I need a complete set of attitude angles of the aircraft (pitch, roll and yaw or equivalents) during flight. Can anyone tell me where to get this data?
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1$\begingroup$ get on a flight with a gyro and log the data? $\endgroup$– ratchet freakApr 17, 2015 at 9:36
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$\begingroup$ Hi Rebecca, welcome to Aviation.SE. I am voting to close the question as too broad, as pitch, roll and yaw will depend on too many factors, e.g. aircraft type, departure and destination airport (route flown), takeoff weight, distance of flight (and thus, fuel load). The values will be different for each flight. $\endgroup$– SentryRavenApr 17, 2015 at 9:41
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1$\begingroup$ Hi Rebecca, you are assuming that such data is available, I do not think it is, as it would not make sense (or it could be sensitive information if recorded during test flights). $\endgroup$– FedericoApr 17, 2015 at 11:00
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6$\begingroup$ Welcome. Provided you're aware that sun exposure will depend on the overall direction of the flight (e.g. N-S vs E-W), I think you can obtain data for a given flight by using a computer flight simulator. You may want to get touch with such users community, e.g. AVSIM and X-Pilots. They may be able to record a flight and provide the attitude data set. $\endgroup$– minsApr 17, 2015 at 11:03
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5$\begingroup$ I suspect what is important is that planes spend 99% of their time straight-n-level. Even when they bank, they typically bank less than 30 degrees, and pitch less than 20 degrees, and that is only for relatively short times. (I don't see how yaw affects sunlight incidence, as it is effectively just flying on a different heading) $\endgroup$– abelenkyApr 17, 2015 at 13:39
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3 Answers
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To answer the question as asked, such data is out there, although it may be hard to get. A flight simulator program is probably much easier, although the real answer to the question probably is, the effects of anything other than straight & level flight are probably dwarfed by the effects of DIRECTION of flight coupled with time-of-day (i.e. is the sun overhead, or low on the horizon to one side or the other, or ahead of or behind the aircraft), and the effect of cloud cover.
Airlines capture exactly the data being discussed as part of the Flight Data Recorder -- one of the two famous "black box" recorders (the other being the Cockpit Voice Recorder). This data is routinely downloaded by the airlines' maintenance departments and analyzed as part of Flight Operations Quality Assurance or FOQA programs. They can see roll, pitch, yaw, heading, altitude, position, track, and dozens if not hundreds of other parameters, all on a moment-by-moment basis, and the analysis of this data is used to inform any number of proactive safety efforts. Rather than waiting for an accident, they can see where things are starting to drift away from what's desired, and take preventative actions.
The problem here is that FOQA data is extremely sensitive, and for an outsider to get access to it is probably somewhere between extremely difficult, and absolutely impossible.
The next step down from that would be the logged data as has been discussed in the various comments, and I'm not smart enough on those specifics to add anything useful to what's already been posted as far as where and how to get those logs.
After that, it is possible to record data yourself, with the right equipment (not cheap). Using an iPad with Foreflight and an AHRS unit (essentially a self-contained INS, with receivers for things like XM satellite weather, GPS, and ADSB, you can record a track log that includes all the parameters mentioned.
Here's the issue: if you're paying for that equipment and the flight time, you will want to get DATA for your efforts... so let's go do STUFF so we have an interesting track log: do some holding, fly a few approaches, maybe a steep turn or a stall series. Because that's much more interesting DATA!
But the simple fact is that when airplanes are actually being used for anything besides flight training, most of what they're doing is simple boring straight & level flight, probably on autopilot. Most of the maneuvering happens at the beginning & end of the flight, on the departure and then on the arrival and the approach, and that all happens at lower altitudes where clouds will have the greatest influence how much sun your solar collectors are getting. Up in the 30-to-40-thousand feet range is where most of the cruise flight happens, mostly straight and level, and with most (though not all) of the sun-blocking clouds below you.
For a realistic estimate of how much solar energy your panels can get, I strongly suspect that you'll do best with an assumption of straight & level flight, and models of the various possibilities of direction of flight and time-of-day. And combine that with estimates of how cloud cover will affect your ability to collect solar energy (remembering that plenty of flights happen at night).
A really accurate log of a particular flight could allow you to calculate to fairly high precision how your received energy would vary over time for that exact flight, but when you want to generalize that out to a large number of operations, you'll need to look at the factors that influence collection the most, and those will be the variables other than detailed records of roll & pitch.
answered Apr 17, 2015 at 22:09
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FlightRadar 24 has an API that you can get data from. This is only from aircraft with ADS-B transponders, so it excludes some smaller and older planes. This would indirectly:
- Give you points with which you could calculate the turns.
- Give you pitch as the rate of climb.
This might give you a bigger but less exact dataset. Unfortunately, you might be disappointed in that normal commercial aircraft make relatively few manoeuvres at cruise.
Depending on the sort of simulations you might find that making a simulated flight in FlightGear (Open Source Simulator) might yield better results. If memory serves me right there is some equivalent to a flight data recorder so you can pull the data when you are finished.
answered Apr 17, 2015 at 13:10
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$\begingroup$ I'm giving FlightGear a try. Thanks to MikeFoxtrot and everyone who gave me pointers above. I think I have enough leads to find the data I need. $\endgroup$ Apr 17, 2015 at 15:09
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$\begingroup$ ADS-B data doesn't seem to include attitude, according to this SKYbrary page. Do you confirm it is part of the technical specifications? $\endgroup$– minsApr 17, 2015 at 18:50
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$\begingroup$ @MikeFoxtrot: Thank you for the link. You are right, and ADS-B seems pretty rich regarding information broadcast. $\endgroup$– minsApr 18, 2015 at 17:28
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Assuming that you are asking this question to come to an optimum design point and conclude on the likelihood of different attitudes that can be seen by an aircraft.
- Yaw angle (heading) is the simplest part: as aircraft fly all around the world, you can take all possible heading angles into account. (Reasoning: aircraft fly to all directions possible. If you need to go into statistics of the subject, you can multiply the number of flights for each of the aviation hiways.)
- For Pitch angle, you can assume that during climbout, depending on the aircraft specifications, there will be an angle from a few degrees to ten plus degrees (larger climb rates involve military aircraft). And during descent, a negative angle of similar amount would take place. During cruise, pitch angle is close to zero: might change zero point some degrees as fuel is burnt and when the aircraft gets lighter. Therefore, a pitch angle of zero should be the optimum design point for any solar-harnessing system on an aircraft. Please keep in mind that the aircraft body (fuselage, wings and tails) surfaces have local surface normals.
- For Roll angle, unless you are looking for a loitering platform (where the aircraft turns around a location for long periods of time), the roll angle will be very close to zero for the straight legs of the flight. Turns will occasionally occur with bank angles of 20 to 30 degrees (again, depending on the radius of the turn, and the flight characteristics of the aircraft). Turns take up such a small fraction of the flight time that they can easily be ignored.
I'd like to also refer back to your main question, of where to find flight data. In case you really need it, there are online flight simulators, and their servers may have pre-recorded data. Otherwise, plugging into a server and recording the live data of flying aircraft could be considered.
Time and location of the aircraft is one other important factor for determining the sun's angle relative to the aircraft.
- For time, you can assume any time of the day and year.
- And for location, only the poles are not covered (there are meteorological stations up to 72degrees North,and 52 degrees south). Existing flight routes (please see "enroute charts") can be utilized to have a better understanding of where aircraft flights take place.
Note that, military and commercial flight data (attitude) is generally considered confidential and proprietary.
