Buster,
As part of my Aero Eng degree course, I designed an angle of attack indicating system for a light aircraft. The most important aspect of predicting the stall is angle of attack and as has been said above, the stall angle of attack depends on flap configuration. It looks like you are trying to cover a number of issues here and it may be worth concentrating on one or two of them, with the others as suggested extensions for the product. The reason I say this is that often in degree projects (I have done three and seen many friends with theirs), it is easy to have eyes too big for your time frame! Perhaps split it into stall prediction, navigation and airspace warnings and approaching limit warnings (such as g load and never exceed speed). The days of instruments totally failing, while not gone are diminishing and it seems like you are trying to achieve a 'catch all', which although a good idea, may be too involved and produced in other systems such as EGPWS, TCAS and Stick shake.
However:
For Navigation alerts, a GPS is great, a database can tell you where the airspace/danger ares/hills are warn you depending on rate of approach and distance etc. Some like the Skymap already do this. Added altitude information is required really, as the GPS altitude is not the altitude above sea level, but the altitude above the GPS datum, which is only an approximation to the world. GPS altitude is probably the least accurate of the paramaters GPS will give you.
For limits protection, it will depend on the limit, for example never exceed speed is an INDICATED airspeed and depends on the pitot system. For instance, in a huge wind it would be possible to be flying backward over the GROUND but approaching never exceed AIRSPEED in something like a C152 (more of a thought experipent than actuality I hasten to add!) so a GPS speed read out would be near useless. Similarly, facing the other way, our imagined aircraft could be well over the numerical never exceed in terms of groundspeed, but no where near it in terms of airspeed. Also, g limits would require a g meter, mach limits a mach meter (or at least the inputs to one and a computer). For limits protection a computer attached to a g meter and the pitot static system would be much more useful than a GPS I think.
Stall protection has already been achieved in many areas using different systems, but most are either a simple vane or reed (such as on the Cessna 152) that give a warning of a certain angle of attack. The more involved ones take account of flap position. Look at a company called Rosemount for vane and rotating slit type AOA transducers.
In the aircraft I fly (Jetstream 41) there are two AOA vanes, one each side. We have EFIS screens with a speed tape down the left hand side and the high and low speed warnings appear as a red tape next to the normal speed tape. Both vanes are active and give local angle of attack continuously. If either approaches the stall angle, the stick shaker activates, if both approach the stall angle, the stick pusher operates. The red tape changes position the whole time depending on the angle of attack the vanes sense at any given time. For instance if you were approaching the flare right on the edge of the red tape (we do not do this!) all would be well until you flared. The inertia of the aircraft would take it along the same flight path for a short time, even though the nose was raised, thereby increasing the angle of attack (for a short time, until things have settled down) so the warning tape rises a bit and the stick shaker would be set off. I have done this in the sim and it is not nice, especially if you flare suddenly and set the stick pusher off!!! The point being that with gusts, or during a manoeuvre the speed tape changes position to give you a visual warning of the stall and it takes into account the local airflow, which at that time is the most important factor affecting the stall. With flaps the red tape moves again.
Try also looking at NASA's AGATE (AGARD?) project which is something like Advanced General Aviation something or other, the project is researching glass cockpits, HUD's, and lots of other weird and wacky things to fit into light and GA aircraft and is basically mapping out the possible 'future' of GA.
Hope all this helps. Feel free to email if you want to ask anything or if you think I may be able to help.
Good luck,
J-R
[email protected]
{Edited to correct my mistake as pointed out below.}