[Spaceships] SS Mecha vs. HT/UT Tanks, and 'ships vs. jets

[Langy]

Tzeentch, read the rest of my post. I calculated the number of modules from the actual mass of the various items - the F-22 holds 9 tons of fuel and has 4 tons of jet engines, for example. It also only has a thrust/weight ratio of about 1.0, which is why its three jet engines only provide 1G of thrust.

I used a medium battery because the F-22 usually has either two or three types of missiles/bombs - in ground attack mode, it carries 2 AMRAAMs, 2 Sidewinders, and one type of bomb (either 8 small diameter bombs, 2 JDAMS, or 2 WCMDs as listed in Wikipedia). It doesn't actually matter if it's a Medium Battery or if its a Hangar Bay, of course, but I prefer an internal weapons battery be listed as an actual weapon battery instead of a hangar bay.

I gave it armor to fill up space. The only parts that I know have the right number of systems are the engines, internal weapons, and fuel tanks - I don't have mass estimates for the rest of the fighter. You could just as easily switch an Armor system for a third Defensive ECM system, but I don't know what else you could put on an F-22 fighter jet without it not making much sense. Can't outfit it with more weapons, since it doesn't carry any more guns, for example. Same deal with the external clamp/hardpoint issue.

-- Jet Engines in Spaceships are efficient, but its never stated if thats endurance at max speed or not. Six hours endurance at some sort of cruise doesn't seem to outlandish in the design below.

True, but I used the F-22's maximum range (total) to figure out how much fuel endurance each fuel tank supplied. It was 10 minutes per tank. Six hours at cruise seems excessive for any normal jet engine.

Other jet engines can be much more efficient - an A-10 Thunderbolt II has a very long ferry range, giving it a time in the air of around eight hours, but when used in combat it might have an endurance of between two and four hours (depending on what the stats mean on the A-10's Wikipedia page).

[Tzeentch]

Originally Posted by Langy

Tzeentch, read the rest of my post. I calculated the number of modules from the actual mass of the various items - the F-22 holds 9 tons of fuel and has 4 tons of jet engines, for example. It also only has a thrust/weight ratio of about 1.0, which is why its three jet engines only provide 1G of thrust.

Spaceships 7: Strange and Alien Spacecraft has a Turbofan and Afterburning Turbofan module that might fit this better.

[RedRager]

Originally Posted by Langy

True, but I used the F-22's maximum range (total) to figure out how much fuel endurance each fuel tank supplied. It was 10 minutes per tank. Six hours at cruise seems excessive for any normal jet engine.

Other jet engines can be much more efficient - an A-10 Thunderbolt II has a very long ferry range, giving it a time in the air of around eight hours, but when used in combat it might have an endurance of between two and four hours (depending on what the stats mean on the A-10's Wikipedia page).

There's much more to an aircraft's range, endurance and speed figures than wikipedia is going to tell you.

For example: You're using the supercruise speed and the F-22's listed range to determine it's endurance, which will lead to some funny numbers. Supercruise is not the 'cruise speed' of the F-22. It's the top speed at which the F-22 can fly without engaging afterburners, which are horribly inefficient from a fuel burn perspective. Off of the top of my head, I'd say that it's maximum range is found at a speed roughly half of that at which it supercruises - giving us an endurance of three hours. Furthermore, it's maximum-range speed is different from it's maximum endurance speed - I'd guess maximum endurance is found at a speed roughly 70% of maximum range speed, giving us about four overall hours of flight time. Guesstimating from what I know about the fuel burn of an F-16 at high altitude (about 3000 pounds per hour, plus or minus 1500 depending on loading, speed, and altitude, doubled for two engines, divided by 26000 pounds of total fuel) gives us about 4.33 hours of endurance - not the six hours that spaceships claims, but close enough and with enough fudge factors that I'd call it a good approximation.

Supercruise on the F-22 corresponds to about Mach 1.5 - I'd guess that the top speed for the F-22 at full burn and at high altitudes with empty bays and almost-dry tanks will fall at about Mach 2.2 - Basic fractions reveal that that's a top speed of 1790 MPH, and because of the altitude differences in which those numbers are achieved, it might be much more. - Again, it doesn't match up with the values in spaceships, but I'd call it fairly close, and I also don't know about the assumptions made in spaceships about the realm of flight in which those numbers are achieved.

[panton41]

Looking at the write-ups for the F-22 it got me thinking about my own questions on space fighters based off the modern model. Is it pretty typical to model a weapon bay as a "Hanger" and external hard points as an "External Clamp" and hand wave away the details of them actually carrying weapons? And for that matter, might this be addressed in Spaceships 7?

[SpaceGurper]

well once SS7 comes out to e23 I'm sure this thread will be modified.

[vicky_molokh]

Tried making a UT Light Battle Tank with the new SS rules, including the official optional armour density option. End result is actually pretty close to the stats found in Ultra-Tech.

Changing the (single) 2-PP Tracked Drivetrain to a single system worth of Robot Legs changes Acceleration and Move from 2 yards per second squared & 20 yards per second to 5 & 5 respectively. However, Hnd/SR changes from -3/5 to +3/1. That's an improvement of +6 to Dodge. With Driving (Mecha) of 12, this grants an average Dodge of 9, which is kinda OK; with an ace driver at Driving-16, it becomes 11, which is nothing to sneeze at. (For comparison, a tank will have a Dodge of 3 at skill-12 and 5 at skill-16.)

I'll take a look at the MBT found in HT a bit later.

[Langy]

I made a TL8 Main Battle Tank based on the Spaceships rules a while ago. You can find it here.