# Insanely fast

#### Lane Shutt

##### Mongoose
Has anybody taken a good look at the vehicle speed tables?

I recently did a reality check and came up with some disturbing results.
You can design a wheeled vehicle, with a relatively small power plant, that can achieve a base speed of 500 m/ round and charge of 2000 m/round.

The speed of sound is 340 m/s or 2040 m/round

Ground vehicles do not suffer control modifiers until a speed of 301 kph

Most tanks can be designed with a base speed greater than a present day tanks max speed. By the rules the cruising speed is double base.

You can design a prop driven aircraft that can exceed the speed of sound.
AFAIK this has only been approached in a steep dive, the prop becomes inefficient as it approaches supersonic speed.

Hybrid engines state that the SCRAM Jet takes over at Mach 3, or a speed of 6000 m/round, but the tables only allow speeds of 5000 m/round.

There is no minimum speed for aircraft. Stall is a result of a failed pilot check, more likely since the modifier is worst (-8) at 300 kph and best at Mach 1.

Although not a technical problem there is an odd naming convention.
The speed table is named Base Max Speed. You calculate Max speed by multiplying Base Max by 10 except for Helicopters which do not multiply base max speed.

Lane Shutt said:

You can design a prop driven aircraft that can exceed the speed of sound.
AFAIK this has only been approached in a steep dive, the prop becomes inefficient as it approaches supersonic speed.

To my defence, I designed the rules with a big book on aircarft technical readouts and access to a real fighter pilot trainee

There is no minimum speed for aircraft. Stall is a result of a failed pilot check, more likely since the modifier is worst (-8) at 300 kph and best at Mach 1.

Which is a construct to reflect the complicated interaction of thrust, lift, drag and gravity; basically, the lower you fly an aircraft, the more likely you're going to get a result of a stall; a good pilot might -still- pull it off, but it's difficult.

Cheers

Mongoose_Al-X said:
To my defence, I designed the rules with a big book on aircarft technical readouts and access to a real fighter pilot trainee

In general the design system is quite good. I still doubt you will find a trans sonic prop driven aircraft in your books, and few that can hit Mach 3.

Mongoose_Al-X said:
Which is a construct to reflect the complicated interaction of thrust, lift, drag and gravity; basically, the lower you fly an aircraft, the more likely you're going to get a result of a stall; a good pilot might -still- pull it off, but it's difficult.

AFAIK all aircraft have an absolute minimum speed to maintain lift, below that they may be controllable but required to drop altitude.

Aircraft design plays a huge role in what that min speed is, in general a higher max speed implies a higher min speed. Most people learn to fly in small, low speed, stable, aircraft and work their way up to faster jets.

In the last 100+ flights I have been on most have been under 200 kph. The pilot easily maintained control at 140 kph, even with the door open and people hanging on the outside. I seriously doubt he had a -8 penalty to piloting rolls.

I think several speed related problems can be overcome with simple solutions.

Base speed becomes minimum safe speed, handling modifier +0.

Max speed for propeller driven aircraft is 5 x minimum, limited to a max of 2000.

Max speed for Hybrid engine aircraft is 15 x minimum. This allows them to reach Mach 3 and fits the text description.

Handling modifier not used above safe speed.

For speed less than Min Safe apply a handling modifier of -2 per 20 m/ round.

My understanding of the piloting roll is that you don't need to make them for everyday flying but for more difficult actions such as acrobatics and dogfighting.
Coming from someone with their pilots license at 140kph it is quite easy to control unless you start actually having to do things that might be considered a little difficult and then the -8 to piloting checks is quite fair i think. I have to admit i haven't read the book and am only going off what is in the post.

After reading a bit more the -8 handling mod is not as severe as I thought. I found that basic maneuvers have a DC 0. Adding a design feature for low speed handling would be reasonable though.

If you used my proposed min speed equal to the base speed the low speed handling would provide a +4 handling bonus between the min speed and 500.

As an example of insanely fast vehicles designed using the Armored Companies design system I present you with the extreme example.

Mercury priority courier
.5 ton personnel sized wheeled motorcycle, spun diamond
Crew 1
ACC/ Dec 30/50
Base Speed 500 (300 kph) +0 control mod
Max Speed 2000 (Mach .98) -6 control mod
Handling +2
Total mass 1.05 ton + 1.1 ton cargo
Cost \$1,025,000

Fuel Cell 'A' 10 pp orbital alloy
Turret, orbital alloy, designated as cargo platform, cargo counts as 1/2 mass
Improved control layout, orbital alloy
Visual scanner
Comms processor

There you have it, a ground vehicle that can transport a ton of cargo at near the speed of sound, problem is the radar would have trouble detecting a hazard before you hit it. Net handling mod at max speed is -4, easy for any experienced character.

Mm, have you considered that, apart from extremes like the one above, the speeds might well be, if anything, conservative? We are talking a techbase 85 years more advanced, after all.

As for supersonic prop-jobs, the US Air Force experimented with some advanced propeller designs for that purpose back in the 1970's. They came to the conclusion that you needed advanced metallurgical and air-flow knowledge to pull it off, but it could be done.

Lets look at the numbers

Base Speeds (Kilometers per Hour)
Code:
``````Vehicle Type      Worst        Best
Tracked            36           69
Wheeled            48          102``````

Best case is an 80 ton vehicle with largest power plant rather than highest speed. These translate to vehicles with max road speeds of 276 kph for tracked and 408 wheeled.

In comparison we have the following tanks
Code:
``````Name             Mass     Speed    Base     Date
M1A2 Abrams        68       67      17     1980s
M60                60       48      12     1960s
Tiger I            57       45      11     1940s``````

So tracked vehicles have doubled or trippled their base speeds for the heaviest in their class.Lighter tanks can have speeds ten times modern, base speeds of 120 kph or greater.

For another perspective, Race cars travel at speeds around 320 kph. About 80% of wheeled and 67% of tracked vehicles w/ Fuel Cells can achieve this speed, including 50% of the 80 ton wheeled vehicles.

This brings up another question, how can a Mek expect to fight tanks on open ground. A tank at max speed would have a -4 to attack rolls while the tank could have DV bonuses of +40 or more. The Mek would have a max DV bonus of +16.[/code]

Umm-isn't there a little line somewhere (I forget where) in the rulebook saying vehicles don't get the speed modivier to DV since they are moving in a fairly straight line, while WarMeks are fairly erratic?
I'll try to find the reference after I get off the range today.

You are correct.
I hate it when they hide rules at the last line of a descriptive paragraph. Not to mention a combat mechanic rule placed in the Speed section.

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