My X-15 from Dynasoar is ready to fly, except for balancing.
Frank says the CG should be 5/8" aft of the wing-strake joint, but I wanted to see where the CP is, so I modeled it in Rocksim and Open Rocket. (Disregard the CG in the diagram, as I did not model any internal components.)
OR puts the CP 2" aft of the wing-strake joint.
Barrowman (in Rocksim) puts it at 1.75".
The Rocksim stability equations put it at 2.54".
And, the cardboard cutout method in Rocksim puts it 4.4" aft of the same spot.
With the CG at Frank's recommended 5/8", its stability margin (in calibers) is: 0.43 per Barrowman; 0.53 per OR; 0.74 per Rocksim; and, 1.45 per cardboard cutout.
If I put the CG at 1.8" aft of the wing-strake joint, it would be unstable per Barrowman, marginally stable per OR and Rocksim, but have a 1.0 caliber stability margin per the cutout method.
What would the actual flight characteristics be in boost?
Frank says the CG should be 5/8" aft of the wing-strake joint, but I wanted to see where the CP is, so I modeled it in Rocksim and Open Rocket. (Disregard the CG in the diagram, as I did not model any internal components.)
OR puts the CP 2" aft of the wing-strake joint.
Barrowman (in Rocksim) puts it at 1.75".
The Rocksim stability equations put it at 2.54".
And, the cardboard cutout method in Rocksim puts it 4.4" aft of the same spot.
With the CG at Frank's recommended 5/8", its stability margin (in calibers) is: 0.43 per Barrowman; 0.53 per OR; 0.74 per Rocksim; and, 1.45 per cardboard cutout.
If I put the CG at 1.8" aft of the wing-strake joint, it would be unstable per Barrowman, marginally stable per OR and Rocksim, but have a 1.0 caliber stability margin per the cutout method.
What would the actual flight characteristics be in boost?
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