Air performance

ericthered · 03-11-2021, 08:28 AM

Last year I did an in-depth "down shifting" of the stats for aircraft using spaceships on my blog, trying to get stats that more closely match TL8 reality. The tweaks I made that you are interested in are as follows:

Streamlining:

There is a lot more to streamlining that simply streamlined and unstreamlined. I use the following numbers as the "base speed" in the equation for airspeed spaceships gives on page 35.

If you're streamlined like a rocket, bullet, space shuttle, or SR-71 blackbird, use the base speed of of 2,500 mph from the book.
If you've got decent control surfaces and can meaningfully turn, but are still streamlined like a fighter jet, use 1,500 mph as your base speed.
If you're streamlined like a modern car, or under SM+5 and have control surfaces, use 500 mph as your base speed.
If you're not streamlined, use 100 mph as your base speed.

Additionally, under 1G, multiply the base speed by the fraction of 1G, not by the square of the fraction of 1G.

Turbofan Engines:
The thrust for Turbofan Jet Engines are twice as high as they should be: individual turbofan jet engines have thrust to weight ratio's of about 5, not 10 (to be honest, even that is a high number, 4 is more typical). The thrust for down shifted turbofan jets are half of their listed values.

The numbers you get aren't perfect, but they are much closer.

03-11-2021, 08:28 AM	#13
ericthered Hero of Democracy Join Date: Mar 2012 Location: far from the ocean	Re: Air performance Last year I did an in-depth "down shifting" of the stats for aircraft using spaceships on my blog, trying to get stats that more closely match TL8 reality. The tweaks I made that you are interested in are as follows: Streamlining: There is a lot more to streamlining that simply streamlined and unstreamlined. I use the following numbers as the "base speed" in the equation for airspeed spaceships gives on page 35. If you're streamlined like a rocket, bullet, space shuttle, or SR-71 blackbird, use the base speed of of 2,500 mph from the book. If you've got decent control surfaces and can meaningfully turn, but are still streamlined like a fighter jet, use 1,500 mph as your base speed. If you're streamlined like a modern car, or under SM+5 and have control surfaces, use 500 mph as your base speed. If you're not streamlined, use 100 mph as your base speed. Additionally, under 1G, multiply the base speed by the fraction of 1G, not by the square of the fraction of 1G. Turbofan Engines: The thrust for Turbofan Jet Engines are twice as high as they should be: individual turbofan jet engines have thrust to weight ratio's of about 5, not 10 (to be honest, even that is a high number, 4 is more typical). The thrust for down shifted turbofan jets are half of their listed values. The numbers you get aren't perfect, but they are much closer. __________________ Be helpful, not pedantic Worlds Beyond Earth -- my blog Check out the PbP forum! If you don't see a game you'd like, ask me about making one!