Air Force ready to deploy 30,000-pound 'super bomb' on B-2 bomber

That brings me to a very good question: How do they actually determine the Max Payload of a bomber anyway?

I used to think they would try different combinations until they made the plane too heavy to take off. However, what you are saying here suggests that would not be correct.

Would you share with us how they figure this out?

Tim

The airframe will have a Maximum Takeoff Weight limited by three factors -

1. the structure will have an upper load bearing weight limit
2. the engine thrust will have an available power limit
3. the wing design limits how much lift can be generated

All of those three factors will in the end restrict the maximum takeoff weight of the aircraft, and the design will take them into consideration, making tradeoffs in some areas to increase others.

There are a number of maximum weights an aircraft design must take into consideration:

1. Maximum Empty Weight - weight of the structure itself
2. Maximum Zero Fuel Weight - weight of structure, crew and payload without fuel
3. Maximum Takeoff Weight - weight that the aircraft cannot exceed to takeoff
4. Maximum Ramp Weight - weight limit on taxiing and hard stands
5. Maximum Land Weight - above this weight landings place undue stress on the airframe, reducing the frames life. This is typically well below MTOW, which is why you see airliners dump fuel or circle in case of emergency.

To increase one of these, you have to increase all of them - the MEW to add extra scructure to handle heavier loads, the MZFW to increase payload, the MTOW weight to get it into the air, the MRW to get it to the runway and the MLW to handle emergency landings.

You cannot simply add more payload and reduce fuel load, unless you already compromise payload for extra range - the load bearing structures are different for the different areas of the aircraft and do not tradeoff against each other.

Hope that helps.

Also, in addition to my previous post, there are a number of local concerns that limit takeoff weights -

1. temperature - the hotter it is, the less dense the air is and the less thrust is available from the engines

2. height - the higher you are above sea level, the less dense and thus the same result as above

3. temperature - yes, Im listing this twice, but for two seperate reasons! The colder the air temperature is when you fuel the aircraft, the lower the specific density of the fuel, meaning you can carry more fuel per kg of fuel (wacky concept) than you would later in the day. This allows a slight (3 or 4%) increase in range for essentially no cost elsewhere as you arent exceeding the MTOW

RichardPrice ,

Thanks for the wonderful explaination! That has to be one of the most through and well constructed answers I have seen on ATS in a long time. Hats off ot you for a job well done.

Tim