Need some tips on speed...

[flyr98]

...with military grade motors too...

 

[speedyweasel]

Oh, sure! I fly my rockets with Thiokol all the time!

Heh... I wish.

 

[Nate]

Originally posted by SpeedyWeasel
Oh, sure! I fly my rockets with Thiokol all the time!

Heh... I wish.

Thiokol? Should I be alarmed that I don't know what that is?

 

[speedyweasel]

Here's what it is: en.wikipedia.org/wiki/Thiokol
The same stuff that propels about half the U.S.' rocket-based systems, including the Space Shuttle, Delta, Titan, Pegasus, Hellfire, Sidewinder, and many, many more.

 

[Nate]

hmm...ok, so basically they make all the stuff that makes rockets go! that's pretty nifty, but word on the street is that White Lightning is pretty much the same formula as is used in the space Shuttles SRB's....so in reality, you are sorta flying with Thiokol!

 

[jraice]

For 2"-3" diameter rockets, what is the best fin design for optimal speed/altitude? Also, should I go with 3 fins or 4 fins? 3 is less drag because there are less fins, but then the outcome is larger fins. Also, is a long fin without much span better then a fin with a lot of span (can a fin have to little span?)? Thanks, just finishing the rocksim file for my CF rocket, just got the parts 10 minutes ago.

 

[dwright1542]

Originally posted by cjl
Wow - you don't think small. Now when is the min. dia. 75mm full N ?

The 75mm x 36" of propellant can be a 0% N with the right propellant.

I flew one with a red propellant many moons ago that was an N 3300:

https://www.dgmicro.com/opl/beast.htm

(Wow, I just realized that it is time to get back to updating the webpage)

-D

 

[cjl]

Originally posted by Nate
hmm...ok, so basically they make all the stuff that makes rockets go! that's pretty nifty, but word on the street is that White Lightning is pretty much the same formula as is used in the space Shuttles SRB's....so in reality, you are sorta flying with Thiokol!

Not quite. I don't have the WL formula, but the SRB formula is (from what I've heard) QUITE a bit higher in Al, and in addition, has a much higher burn rate. I've also heard that SRB propellant doesn't really work that well in smaller motors. In addition, WL has an ISP of about 200s, while SRB propellant is in the 260s range.

Gary, care to interject?

 

[cjl]

Originally posted by Mike Fisher
One step at a time, grasshopper. The difficulty increases as the diameter goes up. Smaller diameter hardware is more resilient to higher pressures. The head end pressure in these long motors can get out of hand really quickly.

The extreme l/d motors are just a diversion from my main projects anyway, which center around motors with exotic grains and aerospike nozzles.

Mike Fisher

Yep - that post was more than halfway a joke . I definitely want to hear about the 54mm M, and PICS (if you can catch it, of course)

 

[rocwizard]

Originally posted by Nate
ok, so that rocket hit mach 4 in under a second...can anyone beat that? I know there's a missile (like the Nike Ajax or something) that hits mach 5 in 2.1 seconds, but that things just an enormous boosted dart.

I've got a project under way that has the potential to do Mach 6-7 in just under 3 seconds. It's aggressive to say the least. I'll share details when the time is right.

 

[jraice]

Wow, mach 6-7 in 3 seconds? That must be a large motor. A while back that would be a speed record for atmospheric vehicles, currect? Nasa's scramjet reached a speed greater then that setting a new record...I believe it was greater

 

[cjl]

Originally posted by jraice
Wow, mach 6-7 in 3 seconds? That must be a large motor. A while back that would be a speed record for atmospheric vehicles, currect? Nasa's scramjet reached a speed greater then that setting a new record...I believe it was greater

AFAIK, the record for anything manmade in the atmosphere is the Apollo capsules - they hit it doing mach 30, or 25000mph

 

[jraice]

I see, well after posting my thought I then thought about the space shuttle, and that goes 17 thousand MPH I believe, so I guess that could be the fastest vertically launched vehicle and the apollo capsle is the fastest of all time... guess mach 6-7 isnt that wild compared to NASA's work like I thought it was...

 

[jraice]

I see, well after posting my thought I then thought about the space shuttle, and that goes 17 thousand MPH I believe, so I guess that could be the fastest vertically launched vehicle and the apollo capsle is the fastest of all time... guess mach 6-7 isnt that wild compared to NASA's work like I thought it was...

 

[rocwizard]

Originally posted by jraice
... guess mach 6-7 isnt that wild compared to NASA's work like I thought it was...

Oh, well I guess I'm just wasting my time then, dabbling in such low hypersonic speeds and all.

 

[jraice]

I just thought that was something competing with NASA (VERY serious stuff) but I could never dream of building something to go past mach 3 so you have some serious skill and that is an amazing feat. cant wait!

 

[rocwizard]

No worries, I was just messing with you, hence the

 

[jraice]

Gotcha, sweet rocket, cant wait to see what is power that, wait, maybe you shouldnt tell me I might like it so much I have to try one myself.

 

[Nate]

I know you can't really tell us too much right now, but for the sake of you already got us really excited, can you give us a little more information? Designing hypersonic vehicles is not an easy task

 

[rocwizard]

Ok, a few anonymous details. It's all carbon fiber, and I mean ALL--> The motor is by all means unconventional in its design. 250 Gs at the end of the motor burn (assuming it makes it that far)...

The project is a highly aggressive one as I stated. 100% success the first time around is by no means likely, but we've got to start somewhere and see where we get with it.

 

[jraice]

Cool, but all we need to hear is a letter and a couple of numbers

 

[rocwizard]

Not yet...:kill:

 

[Nate]

diameter? length? ;-)

 

[r1dermon]

i dont think the shuttle reaches 17kmph inside the atmosphere...also, sure, the capsules went 25000mph into the atmosphere, but they didnt originate in the atmosphere, there's no way they would get that fast if they were wholly in the atmosphere....a few days ago, i read that the fastest manmade object horizontally launched and wholly in the atmosphere was formerly a mach 6.6 rocket, which has just recently been broken by a mach 7 rocket. i'll try looking up in my history, it was pretty cool.

 

[Reed Goodwin]

The mach seven was probably the scramjet. It is designed to go about mach 10.
Reed

 

[cjl]

AFAIK, the fastest vehicle entirely in the atmosphere is a rocket sled (yes, on the ground) at Mach 8.5:

It might make the ultimate amusement park ride, if anyone could survive. Hitting hypersonic speeds of Mach 8.5--that's 6416 mph, in civilian terms--a 4-stage rocket sled took just 6.04 seconds to blast the more than 3-mile length of track at Holloman Air Force Base in New Mexico. The April 29, 2003 test broke a 20-year-old standing land speed record. But at a cost of $750,000, the objective of the run was to do a lot more than get into the Guinness Book of Records.

Pic: (not a drawing or a diagram - this is an actual pic)

 

[jraice]

That rocket sled thing doesnt look to sleek, why such a high drag body? The pic looks pretty unrealistic but I guess it's real, it is on a track at ground level?

 

[cjl]

Yes, it's at ground level (although not at sea level, iirc). As for the high drag - it isn't necessarily as high drag as you think. Hypersonic aerodynamics are more complex than just looking at it and saying "that looks/doesn't look sleek." As for the fake-looking pic? It is because the extreme exposure settings (phenomenally short exposure/extremely high sensitivity camers) can distort colors and can loose minor details.

 

[speedyweasel]

Originally posted by cjl
Yes, it's at ground level (although not at sea level, iirc). As for the high drag - it isn't necessarily as high drag as you think. Hypersonic aerodynamics are more complex than just looking at it and saying "that looks/doesn't look sleek." As for the fake-looking pic? It is because the extreme exposure settings (phenomenally short exposure/extremely high sensitivity camers) can distort colors and can loose minor details.

As usual, a Popular Mechanics Article has great information about one of the coolest toys on the planet. Absolutely amazing stuff... these guys get all the good toys. 13 motors, 4 stages... a couple of motors called SRR's, designed specifically for the HHSTT, "weigh in at a mere 1100 pounds apiece. Yet, during burns of just 1.4 seconds, each produces a total of 228,000 pounds of thrust." Can you IMAGINE??

Oh, and Holloman AFB is about 4,200' above MSL.

 

[cjl]

Yep - PM is a great site. That's where I got my info (and the pic) from.

Side note - those SRR's come to the equivalent of a U1000000. I WANT ONE