Aerospace & Aviation
¨ On a long flight, do you fly towards where your destination will be at the time you plan to arrive?
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ANSWER from Stephanie Wong on 4 August 2006:
On the other hand, when a spacecraft travels to another planet, then you have to think about where it's going to be months or years down the road. That's because the starting planet and the destination planet are not moving at the same velocity with repsect to the the sun. So, in that case, a spacecraft needs to aim to get to where the destination planet will be in the future!
ANSWER from Imagiverse on 24 July 2006:
ANSWER from Bob Raab on 19 July 2006:
Being a family oriented professional pilot is definitely something that you can do. There are a number of occupations for professional pilots. One is the military, however, I don’t believe Costa Rica has an Air Force. Which is probably just as well, since that would be the least family friendly flying job I can think of.
When one says professional pilot, the majority of people think airline pilot, specifically the major airlines. I spent seven years flying for the military, where I learned to fly, followed by twenty-eight with a major airline. You could also fly for a charter service, a corporation, or as a flying instructor. Of the four civilian options I have listed, there may be others I am not aware of, the airlines are the most lucrative while being the most family friendly.
Being a flight instructor is a "day job". You would probably work five days a week and be home every night. However, if you are the sole provider for your family, I doubt that you could make an income sufficient to support your family. As an instructor, unless there is a large number of students, there is a lot of idle time for which you do not get paid. You receive pay only for the time you fly.
Corporate flying, or business flying, can pay well, but it's harder work than airline flying. You often have to load baggage, supervise the fueling of the aircraft, and always do your own flight planning. Depending on the company you worked for, you could be on call 24 hours a day and be away for days at a time. However, you would be aware of the job requirements before you were hired and could make the decision to take the job or not.
A charter service is like a small, unscheduled airline. The charter service owns the airplane and clients pay the service to fly them to wherever they want to go. Charter pilots probably work harder than corporate and for less pay. Sufficient pay can be a real issue here.
With the airlines, at least in the U.S., maternity leave is your right. The amount of time you get to spend at home will depend on your seniority. The more years you work for the airline, the more control you have of your work schedule. The airline I worked for has many women pilots who also have families. There are also those who decide to devote that lives to their career and are happy being married but without children, or remaining single.
With a charter service or with a corporation, maternity leave would depend on the employer's policy. In the U.S., labor laws would require that you receive maternity leave. The amount of time off to spend with your family would vary widely from company to company.
I encourage you to pursue your dream. The best career advice I received as a young man was, "think of something you would do for free and then find someone who will pay you to do that." As you build your flight time you will become aware of the professional opportunities that are available. While you are working to complete you training, put as much time as possible into researching those opportunities. Flying has to be one of the more enjoyable professions. Many times when you are flying at 35,000 feet and you’re looking at a sunset, a mountain range, a coastline, a big city at night, or a string of small towns along a highway stretching into the distance, you will think to yourself, "I can't believe that someone is paying me to do this."
I wish you the very best for your future.
ANSWER from Bob Raab on 10 April 2006:
I have known many pilots who came from a low income background. My hand is up. I worked my way through college making only minimum wage, which at the time was fifty cents an hour. It's like anything else in life, if you want it bad enough you can achieve it. The Marine Corps and the Navy have air cadet programs. Maybe the Air Force also. You must have completed two years of college to apply. To get up to date information on those programs go to a military recruitment office for each service. I am partial to the Marine Corps and Navy. The flying is much more interesting. An Air Force pilot never gets to land on an Aircraft Carrier. If you go to a recruitment office, and you are old enough, do not, I repeat do not, let them talk you into signing up now. Stress that you are interested only in a flight program after you have the required college. A military recruiter will give you the highest pressure sales pitch you will ever experience. Make your mind up before you walk in that you are not joining anything until you have at least two years of college, and that you are definitely not signing anything before that. I hope that is very clear.
ANSWER from Bob Raab on
7 April 2006:
ANSWER from Steve Alessi
on 1 April 2006:
ANSWER from Michael Bastoni
on 30 March 2006:
Finally... a tool that lets you play rocket golf!
Estes is a good source of cheap engines and the Altmark altitude predictor has the thrust curves for nearly any engine!
Here are my recommendations:
You will also need to do some rocket building research. Estes used to publish great materials. I have really old stuff I still use since... well the numbers have not changed and the (Newtonian) natural world has remained constant throughout my lifetime... thank goodness.
One thing you will absolutely be responsible for... and that is STABLE FLIGHT. This refers to the relationship between center of mass and the center of pressure. Look it up 'cause it's vital knowledge.
Rule of thumb. Keep the center of mass above the center of pressure. Again...look it up.
Good luck and ALWAYS WEAR SAFETY GLASSES.
ANSWER from Jenny Alvarez
on 5 February 2006:
For more information look at http://www.aero.org/
ANSWER from Roger Herzler
on 30 January 2006:
Relevant Google search
Tripoli Rocketry Association
High Power Rocketry
National Association of Rocketry
These clubs do high-power solid AND liquid propellants and can custom make their own engines. DISCLAIMER: You should ONLY attempt to get into these hobbies with proper supervision and knowledge. They are high-risk due to the materials involved.
ANSWER from Michelle Mock
on 11 November 2005:
If you need more information about rocket fuel, maybe you can ask a chemistry teacher at your school for information. We hope that you take the advice of our experts and not try to experiment with your own homemade fuel. Work with experienced teachers and advisors when you are experimenting with rockets. While it is pretty funny to read in Rocket Boys how Homer blew up his mother's fence, he's very lucky he didn't blow himself up or kill one of his friends in the process. He learned a lot through his experimenting but he also took huge risks. Did you read the part in the book where Homer wrote: "I prayed it wouldn't blow up in my face"? There is a lot you can learn about rocketry without getting yourself killed.
You can read more about rockets in our Q&A Archives. Also we have two "rocket scientists" interviewed at Imagiverse: Dean Davis and Paul Woodmansee. Read their interviews (and Homer's) and if you have more questions for them, please write again.
Thank you for writing and thank you for the follow up question.
ANSWER from Michael Bastoni
on 4 Nobember 2005:
What distinguishes rocket fuel is its characteristically high, in fact, astronomically high, energy density :). Energy density refers to the amount of available energy (joules, kilojoules or even gigajoules) in a given mass of a substance. Substances that have high energy concentrations are inherently dangerous.
It gets even more dangerous when those substances are specifically designed to release their energy very quickly. Fast release of energy is often (but not always) associated with proportionately high temperatures. High temperatures often yield high pressures that are extremely difficult and dangerous to control and contain safely.
So...stay away from making your own rocket
fuels...there are some very smart people who I know, that have done
some very dumb things, and one of those dumb things is playing with
high energy density substances at home. For more on rocket
fuel visit this website.
I’ve taken the liberty to research the energy densities of various fuels. I thought you might appreciate this:
ENERGY CONTENT, IN JOULES PER KILOGRAM,
OF A VARIETY OF SUBSTANCES
Although gunpowder yields a (lower) energy density than other high energy substances, it is important to note that gunpowder contains its own oxidant and therefore can release energy extremely quickly and within a highly confined space...thus the elements for danger exist: High temperatures and high pressures... Not to mention that most of this stuff is highly toxic.
If you want to fly rockets, then by all means do so...but purchase your engines from reliable manufacturers...and there are many. Apogee and Estes are good companies that make time tested and proven products. These companies also provide mountains of very good educational resources.
I offer an engineering instructional unit called Rocket-Golf. We launch rockets using accurate altitude and azimuth values. We also utilize long hand math and computer simulations that both account for the total impulse and (changing) mass of the rocket. In addition we determine the displacement of the rocket while it is powered as well as its displacement after burnout. We determine acceleration, velocities and positions of the rocket throughout its flight...but most important...and of course most fun is that we predict where the rocket will land. We do cool things like make 100 yard field goals and try to land in hula hoops across the football field. Admittedly we don’t often hit the hula hoops but we often score a field goal, while landing just 25 ft beyond the goal post as predicted! We can maintain 10-15% accuracy most of the time...but over 300 feet this means we can miss by as much as 45 feet and still be 85% accurate!
We make our own rockets...but we DO NOT make our own rocket engines or fuel!
So good luck... Playing with rockets is a way cool way to get smarter faster.
ANSWER from Dean Davis
on 27 September 2005:
Thus, the physical science forces of high-speed, high-acceleration, and extreme temperatures, combined with the need for strength and light-weight drive rocket material secection.
Physical science dictates the operational environmental conditions under which rockets are designed.
ANSWER from Homer Hickam
on 23 September 2005:
What are the similarities between the two? Well, both carry people and both have pressurized cabins so that the people inside are comfortable and have plenty of oxygen to breathe. They also have very similar airframes which means the way the cabin is built. But there the similarities mostly end. Rockets (spacecraft) are propelled by the reaction of a fuel and an oxidizer carried on board. This reaction we see in the form of flames and smoke spurting through the tail of the rocket through a nozzle. The action that results causes the rocket to move forward. This is according to Newton's Third Law of Motion, that for every action, there is an equal and opposite reaction. So the energy of the burning propellant is translated into thrust. Rockets can fly in space because they carry their own oxidizers aboard. This is different from airplanes which operate within our atmosphere. They carry only fuel which utilizes the oxygen in the atmosphere to create the energy to turn a propeller or produce the thrust of a jet engine. Airplanes also use wings to produce lift within the atmosphere. Rockets don't need wings. The Space Shuttle has them so that it can glide like an airplane when it comes back into the atmosphere. All of its rockets are out of propellant when it has to act like an airplane. Still, it is a bit of a combination of both.
As to the physical sciences, of course both rockets and aircraft operate according to the laws of physics, specificially Newton's laws of motion.
15 August 2006
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