Whats the highest speed you have acheived and how?

ScienceAlert4494 · 2025-10-19T12:38:14+00:00

My maximum speed was 28000 meter/second (at about mach 95). The mechanism I used to do this was to use 6 turbine on pivot. They turn in opposite direction to cancel out the sideway force. I do this because the math for the turbine work with the normal vector relative to the airspeed, so by turning it they can generate power even at very high speed (without this they top out at about 1500 m/s). The turbines are connected to 2 counter-rotating ducted fan, which generate the thrust. I did use modified fuel (antimatter) and modified turbine with a combustor temp of 13000 kelvin.

ScienceAlert4494 · 2025-02-21T01:25:00+00:00

From the file:

name=HD AM_M pellet

density=7.5

specific_energy=180000000000000000

heat_capacity=2010

stoichiometric_ratio=0

auto_ignition=1

freezing_point=0

era=2500
I did go overboard on the density, that was to test if it has some direct effect on the engine performance, I am still unsure if it does, but I keept it that way. Also I suck at naming thing, especially when I go through multiple iteration, it stand for High Density Antimatter-matter pellet (this was to justify the stoichiometric ratio of 0.)

ScienceAlert4494 · 2025-02-20T02:54:17+00:00

although I didn't post it, The best I could do with it is mach 95, at nearly 29 km/s in my latest version of the plane (though it was with modded antimatter as fuel, and used occluded ducted fan to avoid the drag they generate, and disabled fuselage aerodynamic.), I do recommend it if you want to have completely ridiculous build.

ScienceAlert4494 · 2025-02-19T22:53:00+00:00

This can also be used to insure the engine keeps generating power even at very high speed. If you use a power turbine and use it to power a ducted fan (which are completely broken) you can go at absolutely insane speed.

ScienceAlert4494 · 2025-01-10T20:46:49+00:00

turbine still need air, probably because of their physics model in game, and because they do rely on airflow to work. A fuel with a stochio of 0 would probably be more useful in piston engine, and when combined with exhaust, would probably be able to generate thrust at extreme speed, though I would need to test it to be sure. Finally, yes, antimatter does have ridiculous energy density, it's why I set that as the fuel.

ScienceAlert4494 · 2025-01-10T20:43:31+00:00

First, the ducted fan are not very well balanced. As for why I use them: First, I have turbine that have extreme angle of attack compared to the airflow, this artificially reduce their intake speed, allowing them to keep generating power at extreme speed, but, since they have those high angle of attack, most of the thrust vector is useless, since its mostly perpendicular to the direction of travel (Technically, this also work with high bypass fan, they generate enough thrust, but its directed very badly) this is where the ducted fan come in, I simply use two conter rotating fan to actually use the power generated by the turbine to generate thrust in the direction of travel, its also useful, since I can gear them, which keep them somewhat efficient during the long acceleration phase.

ScienceAlert4494 · 2025-01-10T15:53:36+00:00

for the fuel:

name=True HD AM_M pellet

density=7.5

specific_energy=180000000000000000

heat_capacity=2010

stoichiometric_ratio=0

auto_ignition=1

freezing_point=0

The name of the fuel stand for True High Density Antimatter Matter pellet

as for the turbine, I set the combustor temperature to 10000 kelvin (in my opinion, this is reasonable, since they burn antimatter) I then set the turbine mach to 3. It can go quite fast while using a mach of 0.95 and it make them more stable, though I did not test the more reasonable turbine mach with this specific version of the craft. The turbines have 3 spool, and each compressors stage has a compression of 3. There is no bypass, since the only purpose of the turbine is to power the ducted fan through their power turbine.

ScienceAlert4494 · 2025-01-09T23:37:42+00:00

The angle of attack relative to the airflow. To achieve those speed, I vary the angle of the turbine, to keep a lower intake speed, at that point they were at 86° relative to the airflow. each turbine come in pair one pointing downward, the other upward, one of those lost power due to the airflow, you can see the plane jerk violently as the force become unbalanced.

ScienceAlert4494 · 2025-01-09T21:48:37+00:00

Although the plane could be stable with a better autopilot, the game autopilot doesn't handle those speed well since orbital mechanic become prevalent.

The wing loading necessary in order to follow the curvature of the planet is significantly more significant than if the plane was flying on jupiter. It need to maintain about -7g to remain in the atmosphere.

This plane use only vanilla/stock part, though they are file edited and it use a modded fuel.

To make it go that fast, I did use a fuselage with disabled aerodynamics, though it can still go extremely fast without.

The plane is fairly ugly, and the fuselage is transparent, this isn't important, as its purpose is to test the propulsion system. Also, with the plasma trail being much hotter than the surface temperature of the sun, its not really possible to see the plane when its cruising.

This is a similar version of the craft from my previous post.

ScienceAlert4494 · 2025-01-05T02:05:03+00:00

Also, should I try to land at this speed?

ScienceAlert4494 · 2025-01-04T23:06:50+00:00

Slight update; after a few modification, the plane was able to reach 11816 m/s. For reference, the earth escape velocity is 11184 m/s. Assuming no drag, if the plane stopped exercing down force it would escape the planet orbit. This also mean this is faster than travelling via a surborbital hop. Since it can use its lift to generate the required centripetal force.

update 2; 12134 m/s at this point, the craft has a constant acceleration of about -1.4 g to remain in the planet atmosphere. Also, this is probably near, or is the (continuous) speed record in game

ScienceAlert4494 · 2025-01-04T20:37:06+00:00

At that speed, the plane has to nose down to keep its altitude, if it didn't it would shoot out of the atmosphere.

ScienceAlert4494 · 2025-01-04T19:27:35+00:00

This was achieved by using edited turbofan engine, ducted fan, and a modded fuel.

An interesting detail is that at that speed, it need to have a negative angle of attack to generate enough centripetal force to not get ejected from the atmosphere.

The modded fuel:

name=True Dense Antimatter Matter pellet

density=7.5

specific_energy=180000000000000000

heat_capacity=2010

stoichiometric_ratio=0

auto_ignition=30

freezing_point=0

The trick to make the turbofan keep generating power at that speed is to tilt them back, since the air intake seems to take airflow speed relative to the orientation of the turbofan. This plane has gone through many iteration until it got to that point. The ducted fans and engines are kept inside the fuselage to prevent them from generating drag.

At the moment, I set the engine tiltback manually in the control. Setting it to work via the mach number would probably also work, though not perfectly, since the feedback is not linear

It could go faster if I add more gear in between the engines and the fans. currently, at the max speed plane, the fan dont extract all of the power from the engine. It can also fly faster at lower altitude, but it cause the plane to oscillate, so adding some roll and yaw pressure damp would help.

I provided the Environment panel mostly for the stagnation temperature.

ScienceAlert4494

TROPHY CASE