Showing posts with label coefficient of lift. Show all posts
Showing posts with label coefficient of lift. Show all posts

Sunday, June 20, 2010

Belite Ultralight Aircraft Stalling Speed

I've run into some interesting discussion out on the social networks discussing or questioning the ability of the Belite ultralight aircraft design to stall at 24 knots.

A quick analysis of the FAR Part 103 rules, as it relates to ultralight aircraft, specifies five critical technical conditions for the acceptance of an aircraft as meeting part 103:

a) Weight, not to exceed 254 pounds, although there are several exemptions.  (Under certain conditions, weight may be as high as 338 pounds, and still meet Part 103.)

b) Stalling speed, not to exceed 24 knots Calibrated Airspeed. 

c) Cruising speed, not to exceed 55 knots calibrated airspeed.  This translates to a True Airspeed of as high as 74 mph (conditions:  10,000 feet; 0 degrees C, 55KCAS) or even higher.

d)  Fuel capacity not to exceed 5 gallons.  Part 103 incorrectly indicates that this is 30 pounds of gas -- which is simply not true.  It can represent up to 33 pounds of gas.  See this link for an explanation.

e)  Single seat operations.  Not much of a technical consideration; this is easy to verify.  If you wanted to get two people in our airplane, each would have to have a butt with a width of 8 inches.

For these FAR Part 103 rules, it is easy to verify a, c, d and e, and thus ensure that your aircraft is a legal ultralight.  (There have also been discussions of why Belite would use a 50HP engine, thus potentially allowing cruise > 55KCAS -- I'll get to that in another post in the near future.)