AEROSPACE TEAM ONLINE
ATO #120 - October 23, 2000
PART 1: Upcoming Chats
PART 2: Worth Waiting For
PART 3: Faster is not Always More Fun
QuestChats require registration. You can register at http://quest.arc.nasa.gov/aero/chats/
I apologize for any inconvenience caused by the early start of last weeks chat. I will make every effort to avoid such a mix up in the future. Jim McClenahen graciously offered to reschedule for -Wednesday, November 1, 2000, 10 AM Pacific. See below. I hope you can join this chat! It will be very interesting. Susan Lee-THURSDAY, October 26, 2000 9 AM Pacific
Virtual Skies QuestChat with George Tucker
George Tucker is a research test pilot. In most cases this requires more than just flying the aircraft. More often than not the project team relies on the research pilot to assist in setting up the projects in such a way that the experiment has the highest probability of getting the data that is intended from the simulation or flight experiment. Read his profile at http://quest.nasa.gov/aero/team/tucker.html
-Wednesday, November 1, 2000, 10 AM Pacific
Jim McClenahen is an air traffic control analyst in the Future Flight Central Facility. He is very familiar with air traffic management. You can read his profile at http://quest.nasa.gov/aero/team/mcclenahen.html
-Wednesday, November 8, 2000, 11 AM Pacific
Andy Hahn is a conceptual airplane designer. He has worked on some conceptual designs for planetary planes. Read his profile at http://quest.nasa.gov/aero/team/hahn.html
-Wednesday, November 29, 2000, 10 AM Pacific
Peter Gage is a design engineer. He has worked on the design of some Mars entry vehicles. Read his profile at http://quest.nasa.gov/aero/team/gage.html
WORTH WAITING FOR
Virtual Skies is an air traffic management project for students and teachers in Grades 9-12. It will be a "project based learning activity" with hands on multimedia to enhance student decision making and problem solving skills. Topics to be covered include Aviation Navigation, Aviation Weather, Communication Air Traffic Management, Airport Design, and Air Traffic Research. Materials will be tied to the National Standards in Mathematics, Science, Technology, Geography and Language Arts.
Planetary Flight is an aerospace project for Grades 4-8. We know how to fly on Earth but what will it take to fly on Mars. This will be an inquiry based learning project to design an airplane to fly on Mars. The stuff dreams are made of!!
[Editor's Note: George Tucker is a research test pilot. In most cases this requires more than just flying the aircraft. More often than not the project team relies on the research pilot to assist in setting up the projects in such a way that the experiment has the highest probability of getting the data that is intended from the simulation or flight experiment. Read his profile at http://quest.nasa.gov/aero/team/tucker.html ]
FASTER IS NOT ALWAYS MORE FUN
by George Tucker
October 11, 2000
I believe it common to think that the faster and flashier an aircraft is the more fun it will be to fly. From experience I would say this is frequently, but not always, true.
Soon after I came to Ames Research Center I was assigned as the project pilot for the simulation of a novel airship concept which the lifting capability of a blimp-like airship would be augmented with a helicopter rotor system on each corner of a rectangular frame attached beneath the envelope. The Goodyear Rubber and Tire Company took notice of the simulation effort and offered our project team an opportunity to fly one of their "Goodyear Blimps" to gain some first hand experience with the dynamics and operational characteristics of a "real" airship.
The appointed flight day turned out to be beautiful, except for surface winds that were sweeping across the aerodrome at 20, gusting to 25 knots. A Goodyear airship Captain met us at the ship which had been towed from its hangar while attached by its nose to its mooring mast, and readied for flight. In the gusty winds it was clear that the airship, as a very large balloon was very much affected by its environment. Each of us timed our jump into the gondola (or cabin) as it floated erratically and bouncing up and down on its one landing gear. The Captain took the seat with the only set of controls, started the two engines and "weighed off" by having the ground crew remove sand bags from the gondola to account for our added body weight. When satisfied with the buoyancy and trim of the ship he signaled the crew chief on the ground in front of the blimp to release it from the mast. From that point until the actual takeoff the airship was held in place against the wind by the two engines and approximately 6 men on each of two ropes that fell away from the nose of the blimp. In a smoothly synchronized maneuver the Captain put the two engines at maximum power, signaled the ground crew to release their hold on the ropes and drove the ship upwards at about a 30 degree angle to get it cleanly away from the ground.
Once safely airborne the Captain throttled the engines back, got out of the seat and said "your ship" indicating for me to climb into the seat and take the controls. The next hour and a half provided one of the most interesting flights I have ever had. We never went faster than 35 miles per hour and pretty much exited in a world that is unfamiliar to most. interesting flights I have ever had. We never went faster than 35 miles per hour and pretty much exited in a world that is unfamiliar to most. Once away from the ground the airship more or less floats along with the ground handling ropes that hang from the nose and swaying lazily back and forth. All signs of the gusty winds are gone. The pilot sits in a slightly elevated chair amongst a set of controls that are very unlike those or an airplane. The elevator part of the flying surfaces at the rear end of the blimp is controlled by a big mahogany-rimmed wheel about 21/2 feet across attached to the right side of the pilots seat. The rudder is controlled mechanically by the pilots feet placed in two metal foot cups attached to long metal bars that come out of the floor of the gondola. Fine control of the pitch attitude is achieved by moving air into or out of two bags, one forward and one aft, which reside within the larger, familiar, cigar-shaped bag that is filled with helium. Changing the relative volumes of the two smaller bags within the larger envelope moves the helium, which is lighter than the air, forward or aft, raising or lowering the nose of the blimp, as required. The intake scoops and exhaust valves on these bags are mechanically controlled by a series of cables, the ends of which hang down from the area above the windshield. The pilot spends a fair amount of time opening and closing air valves with these cables to not only control the attitude of the blimp, but also to maintain the overall pressure within the larger envelope within a narrow range of pressures which keep it from being overstressed--or sagging from under-pressurization! The engines, one on each side of the gondola, provide the propulsive thrust.
The blimp can accelerate out to 35-40 knots with much bellowing from the engines, or quietly decelerate to a speed where it is floating along with barely enough speed to keep the nose pointed. Either way it takes a good bit of time for the speed to change. All in all it was a fascinating way to fly with very little of the mechanics of flying accomplished in a way that is familiar to airplane and helicopter pilots. When the flight was nearing its end we were treated to a demonstration of why airship pilots are a rare and skilled lot. The wind at the aerodrome had increased another 5-10 knots over takeoff and was exceptionally gusty. The highly experienced Captain took the controls back and made two failed approaches to land before finally succeeding on the third. The very real challenge was to drive this big football shaped bag full of air and helium, in the gusty surface winds, down to a landing and have it come to a stop just in front of the ground crew who are waiting to wrestle the airship, with the handling lines, back onto the mooring mast.
What an incredible job of piloting it was! I've never seem a more amazing feat of airmanship, much of it accomplished at a speed no faster than a very fast runner can run. Nor have I ever enjoyed flying any aircraft more. What an experience!