Steve Jackson Games Forums - View Single Post - Pterosaur Size, Weight, ST and Maximum Encumbrance when Flying

Anthony · 02-12-2019, 12:14 AM

Realistically speaking, ST will be 'high enough to keep the dinosaur aloft with a reasonable margin to cover errors, bad luck, and variances in weight from eating and drinking'. This may not be all that strong in absolute terms, but bear in mind that we're applying force way out along the length of a quite long wing. If we assume Q. Northropi had a mass of 250 kg, 5m wings, and the center of lift 2m away from the body, limb torque is 2500N*m per wing (10N*m per kg), and peak at the bottom of a power stroke flying is significantly above that. By comparison, a 62 kg gymnast doing an iron cross is probably managing about 250N*m (4N*m per kg), so the total strength of the wing muscle is at least 10x greater, though the absolute strength is going to vary a bit because GURPS normally calculates ST at arm's length, and at wingtip the QN is applying a mere 500N, as opposed to the 620N applied by the gymnast (of course, a wing isn't an arm, so perhaps you measure at a different point along the wing length).

My problem with the higher end estimates of mass is that the power requirements are rather ridiculous -- because higher weight increases ideal and stall speed, power requirements for flight scale as the 3/2 power of body weight and wind up in the 3 kW range for 250 kg flier with a 11m wingspan.

02-12-2019, 12:14 AM	#4
Anthony Join Date: Feb 2005 Location: Berkeley, CA	Re: Pterosaur Size, Weight, ST and Maximum Encumbrance when Flying Realistically speaking, ST will be 'high enough to keep the dinosaur aloft with a reasonable margin to cover errors, bad luck, and variances in weight from eating and drinking'. This may not be all that strong in absolute terms, but bear in mind that we're applying force way out along the length of a quite long wing. If we assume Q. Northropi had a mass of 250 kg, 5m wings, and the center of lift 2m away from the body, limb torque is 2500Nm per wing (10Nm per kg), and peak at the bottom of a power stroke flying is significantly above that. By comparison, a 62 kg gymnast doing an iron cross is probably managing about 250Nm (4Nm per kg), so the total strength of the wing muscle is at least 10x greater, though the absolute strength is going to vary a bit because GURPS normally calculates ST at arm's length, and at wingtip the QN is applying a mere 500N, as opposed to the 620N applied by the gymnast (of course, a wing isn't an arm, so perhaps you measure at a different point along the wing length). My problem with the higher end estimates of mass is that the power requirements are rather ridiculous -- because higher weight increases ideal and stall speed, power requirements for flight scale as the 3/2 power of body weight and wind up in the 3 kW range for 250 kg flier with a 11m wingspan. __________________ My GURPS site and Blog.