Faster than sound at low altitude

[Torquimedes]

EDIT: 356 m/s Pure Stock. Incrementing meter by meter...

Edited March 28, 2015 by Torquimedes

[norup]

Nicely done, Van Disaster.

The cubic control thingy seems a tad faster. I tried to best your speed jettisoning the undercarriage, only to find it made no difference.

To prove my point, I matched your 366 m/s with this beauty

I look forward to a polished KSP 1.0(?) where things makes sense.

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[Van Disaster]

Hehe, good stuff. It does make a difference in FAR - conversely closing intakes makes no difference in FAR - hence I just ejected the wheels out of habit.

[Starlionblue]

I'm going to be the nitpicky pilot in this thread. Can't help myself. For the record though, I haven't even gotten close to these speeds close to the surface.

The speed of sound is not an absolute. It is dependent on temperature. The formula on Earth for the local speed of sound in knots is 38.94 times the square root of the absolute temperature (temperature in degrees Kelvin). Thus in a standard atmosphere on Earth (15 degrees C at sea level), the speed of sound is 661 knots at sea level (340 m/s).

In a standard atmosphere, temperature decreases by 1.98C/1000ft, and it follows that local speed of sound thus decreases with altitude. Of course in a real atmosphere the lapse rate (change of temperature with increasing altitude) is not constant, so the local speed of sound varies not only due to altitude. Then again Kerbin does not have weather so we can consider it an actual standard atmosphere.

Using the standard lapse rate, at 500m the temperature is 11.75C (284.75K) so the local speed of sound is 657 knots (338 m/s).

I updated the rules a bit. but it's about STRAIGHT flight, so no diving please.

Nitpicking again, straight flight is on the same heading. Level flight is at the same altitude.

Edited March 29, 2015 by Starlionblue

[michaelhester07]

I finally got one that worked well

It wasn't very efficient but it was air breathing engines.

Stock physics and parts.

[Van Disaster]

The speed of sound is not an absolute. It is dependent on temperature. The formula on Earth for the local speed of sound in knots is 38.94 times the square root of the absolute temperature (temperature in degrees Kelvin). Thus in a standard atmosphere on Earth (15 degrees C at sea level), the speed of sound is 661 knots at sea level (340 m/s).

In a standard atmosphere, temperature decreases by 1.98C/1000ft, and it follows that local speed of sound thus decreases with altitude. Of course in a real atmosphere the lapse rate (change of temperature with increasing altitude) is not constant, so the local speed of sound varies not only due to altitude. Then again Kerbin does not have weather so we can consider it an actual standard atmosphere.

Using the standard lapse rate, at 500m the temperature is 11.75C (284.75K) so the local speed of sound is 657 knots (338 m/s).

Meanwhile in KSP...

Temperature measured at 500m via stock thermometer is 17.48C, so that's 341.4 m/s

[Starlionblue]

Meanwhile in KSP...

Temperature measured at 500m via stock thermometer is 17.48C, so that's 341.4 m/s

Perfect.

I guess we can leave the question of whether Outside Air Temperature measurement is compensated for ram rise at high speeds out of it.

[Jumpyyoza]

So when is the FAR leader board coming out? I've got a hypersonic craft waiting in the hanger for it's glory moment at the top of the leader board...

[Tank2333]

Hi

ive made a little dron that got to 335ms/s pure stock

im not sure i can get faster

[KamikazeF0X]

Here comes my FAR Flight !

I can go at 750 m/s with this :

But it's easily feasible to go over 800 m/s