Acceleration Part II. You thought Top Fuel was fast!

[NPloysa]

I saw the acceleration post for the Top Fuel cars and thought of this. Here is some info I calculated for the X-15 rocket propelled aircraft that set the speed record of Mach 6. 7, or 4520 mph, on October 3rd, 1967 and at 354,200 feet altitude.



If a bullet were travelling out of a gun at 3000 fps, or about 2050 mph, and the X-15, travelling at 6630 fps, or 4520 mph, were to cross a start line at the same time, the X-15, in a matter of 5 seconds, would be 3. 5 miles AHEAD OF THE BULLET.



If the X-15 were to be nose to nose with the Top Fuel car, with the car crossing the start line at 300 mph, and both race to the end, the car would make the 1/4 in 4. 5 seconds, and after those 4. 5 seconds, the X-15 would be 5. 4 miles past the finish line.



If you were in the top fuel car, in that 1/4 mile, the X-15 would cross the line 1/4 mile behind you, in about 8 tenths of a second!



Although the X-15 could only sustain a 2-minute powered flight, it could travel almost 151 miles. That's 75 miles a minute!



The X-15 could travel about 3320 feet, or . 62 miles, in the time it takes to snap your fingers once (assuming half-second snapping time).



(I'm tired, someone correct my math if it's wrong!)



Nick

 

[barbwire]

Wow!!!!!!!!!!!!!

 

[Hohn]

Nick, that's interesting.



But if I remember correctly, the point of the Top Fuel post was not SPEED, but ACCELERATION. Not V but Delta V.



It's still amazing.



Justin

 

[NPloysa]

Yeah I know, but I couldn't find any info on acceleration of the X-15.



The website did say it took only 80-120 seconds for the X-15 to reach 4520 mph from a 500 mph launch from a B-52 (reaching max speed at the end of the 80-120 second flight, depending on fuel load). So taking the minimum, 80 seconds, from 500-4520, which is 4020 mph (5896 fps) in 80 seconds, it accelerates, at an average, of 73. 7 feet per second. But, I do not know how to convert that to actual acceleration, since 73. 7 fps is linear.



The acceleration of the X-15 comes out to 23. 54 m/sec squared



While the acceleration of the Top Fuel car (top speed example being 100 m/sec, doing a 4. 5 second 1/4 mile) is 22. 2 m/sec squared.



Of course a 3 second run at 325 miles per hour, or 104 m/sec, comes out to 34. 6 meters per second squared

 

[mberry]

I hate math. ;-)

 

[NPloysa]

I hate math. ;-)

Me too! Unless it's something I enjoy. I mean math in school, hated it. Math for my own knowledge, doing it the way I want, I enjoy.