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Re: Gliding/soaring requirements

Comments inserted,

----- Original Message ----- From: "Mike Habib" <habib@jhmi.edu>
To: "DML list" <dinosaur@usc.edu>
Sent: Monday, September 29, 2008 1:25 PM
Subject: Re: Gliding/soaring requirements

Such gliders have flown 438 miles on thermals alone(at the time, the highest manufacturer claims were 15:1), and more than a few 400+ mile flights.
"recreational" hang gliders may only get 1.2 m/s sink rates, and glides of 12:1, they still regularly thermal for hours, and such gliders were setting the records back in the 90's and 80's with 200-300 mile flights.

Gary Osoba has set a number of world distance records using small sailplanes with weight, span, and performance similar to some of the larger pterosaurs. He has a tendency to use microlift in addition to theremals, and I would expect distance traveling vertebrates with appropriate wingloadings and aspect ratios to do that as well. Some years ago, I asked Gary to do a demo flight for a Discovery News segment, and have some great video of that from the wingtip mounted camera installed on his plane.

A guy on this list sent me a message saying there were some days where he was, they could soar a J-3 cub single engine aircraft.

That was me (JimC), and the location is near Memphis. The fun part is that the J3 is non-electric, so once you shut the engine down for soaring, you can't restart it, and you have to glide back to the airport and dead-stick your landing. Also, since we're underneath the Memphis Class B airspace, we can't soar above 3000-4000 feet, depending upon where we are underneath the Class B airspace (aren't allowed to encroach up into it).

One thing I would be very interested in, is the relationship between the much warmer climate, and thermal frequency and intensity.

It could be very relevant to the large pterosaur discussions, if not early birds.

Definitely worth considering - any thoughts out there?

It varied a lot with time (geologic time that is). Also with oxygen content, since periods of high oxygen levels reduce the pressure altitude (higher pressure = lower pressure altitude, thereby allowing slower true airspeeds to somewhat offset the higher true airspeeds resulting from the higher temperatures). Periods of low oxygen levels have the inverse effect.