You are here:
Careers: Military--Army, Navy, Airforce, Marines, Coast Guard/CG problem
Advertisement
Question
QUESTION: In a question dated 8/16/06, you gave a problem to find the CG that involved 3 axels. I was wondering if the CG is 190 inches from the RDL? 7,500x190=1,425,000
ANSWER: Phil -
I went back and reviewed that particular response, and I only saw an example for a two axled vehicle. Without the numbers you saw, I can't calculate the answer. Please send it to me ... or create one of your own, and I'll give you the answer. As a minimum I need the weight of each axle and their distance between each of them. I don't necessarily need an RDL, as I can give the answer from any of the other known points, i.e., any of the axles.
I'm looking forward to the challenge.
Sincerely,
James Bell
---------- FOLLOW-UP ----------
QUESTION: This was in a question dated 5/2/2006. I was mistaken in my previous question.
Here is one for you to figure out: You have a three axled vehicle.
RDL is 55 inches from the front axle
Distance between first (front) and second axle is 180 inches.
Distance between second and third axle is 45 inches.
Each axle weighs 2500 pounds.
Write me and tell me where the CG of the vehicle is.
---------
My answer was 190.
I'm looking at a possible career change and have always have considered the Air Force. Loadmaster is the career that always catches my eye.
Thanks,
-Phil
Phil -
Your answer matches mine ... here is how I arrived at it:
RDL to first axle = 55 inches * 2,500 = 137500 moments.
RDL to second axle = 235 inches (55+180) * 2,500 = 587500 moments.
RDL to third axle = 280 inches (55+180+45) * 2,500 = 700000 moments.
Total weight = 7,500 lbs
Total moments = 1425000
1425000 / 7500 = 190 inches from RDL
or 135 inches behind front axle and 45 inches in front of second axle.
It looks like your math is right where it should be. There are loadmaster students in their fourth week of training that still can't capture the concept of weight and balance ... it looks like you have a leg up on them.
Put in for that retraining.
Sincerely,
James Bell
Related Articles
Answers by Expert:
James Bell
Expertise
I am a retired MSgt (2004) with 24 years experience in the aircrew career field, both as a loadmaster (AFSC 1A2x1) and flight engineer (AFSC 1A1x1). I have been to every continent at one time or another, and regularly flew 300 to 500 hours a year. I have been involved in the operations in Grenada, Panama, Kosovo, Afghanistan and Iraq. I can answer most questions you may have about enlisted Air Force life in general, assignments, benefits, and enlisted aircrew operations. NOTE: If you have specific recruiting and/or medical questions about how to get into this career field as a civilian, they have changed since my time, so that is best answered by a recruiter or MEPS. I can answer questions about military personnel wanting to RETRAIN. If you are asking about being an Air Force pilot, please be advised my area of expertise is ENLISTED aircrew operations, NOT OFFICERS.
Experience
Loadmaster (AFSC 1A2x1): 7 years - 2,000 hours - C-5A Galaxy cargo plane. Flight Engineer (AFSC 1A1x1C): 7 years - 2,500 hours - C-141B Starlifter cargo plane, 10 years - 3,800 hours - KC-10A Extender aerial tanker. Served as aircrew Flight Instructor, Flight Evaluator and Training Manager
Education/Credentials
Aircraft Loadmaster Initial Qualification - 1980. Mission Qualification (C-5A) - 1981. Fixed Wing Aircraft Performance Course - 1987. Initial Flight Engineer Qualification (C-141B) - 1987. Mission Qualification (KC-10A) - 1988. KC-10 Initial Qualification Course - 1994. Mission Qualification (KC-10A) - 1995. Instructor Qualficiation (KC-10A) - 1997. Evaluator Qualification (KC-10A) - 2000.
©2012 About.com, a part of The New York Times Company. All rights reserved.