- Joined
- Sep 5, 2009
- Messages
- 3,596
- Reaction score
- 1,785
Here is a flight result. I ran DriftCast in the morning before the launch. I used simulations from OpenRocket. Standard atmosphere model for temperature and pressure conditions. I noticed right off the bat that the upwind distances and altitude loss from winds seemed ridiculously low as predicted by OR. Nonetheless, I put the results in the Weathercock table and ran the forecast. The predicted landings were in a good direction for recovery, so launch was a GO!
Actual flight was about 1:20 pm and temps were about 80 deg F. Here is the flight data from the Featherweight GPS:
Apogee = 13,378 feet AGL
Mean drogue vertical descent rate = 61 ft/s
Mean main vertical descent rate = 20 ft/s
So, the inputs to DriftCast were reasonable. Here is the ground shadow of the 1:00 pm prediction (yellow curve), and the actual flight (black curve). The agreement of the drift portion is very good, in both magnitude and direction. The forecast and drift calculations are working well!
What is not good is the upwind magnitude prediction. The difference between predicted and actual landing (about 1200 feet) can be pretty much attributed to the weathercock discrepancy. I am going to re-sim this flight in Rocksim and RASAero and see if there is stronger weathercocking predicted.
Actual flight was about 1:20 pm and temps were about 80 deg F. Here is the flight data from the Featherweight GPS:
Apogee = 13,378 feet AGL
Mean drogue vertical descent rate = 61 ft/s
Mean main vertical descent rate = 20 ft/s
So, the inputs to DriftCast were reasonable. Here is the ground shadow of the 1:00 pm prediction (yellow curve), and the actual flight (black curve). The agreement of the drift portion is very good, in both magnitude and direction. The forecast and drift calculations are working well!
What is not good is the upwind magnitude prediction. The difference between predicted and actual landing (about 1200 feet) can be pretty much attributed to the weathercock discrepancy. I am going to re-sim this flight in Rocksim and RASAero and see if there is stronger weathercocking predicted.