There is no way that this rocket is successful, but darn it I am going to try! (Mach 5+ Composite Case 38mm rocket)

[Brainstormz123]

As someone who has worked on a few (literally 3 so is that a few? lol) hypersonic projects, I can tell you this little bit.

The closer you think you are to getting there, the further away you actually are.

Those who know, know.

One thing else, the more you blow your load at the pad, the slower you are going to go. It is extremely counter-intuitive.

Cool project nonetheless!

I know that the correct way to go really fast and not immediately break up is to get high altitude, which is where the waiting comes in.

However, I want to get hypersonic with as small a rocket as possible. This means not being able to “waste” delta-v on drag, and I instead need to get moving as fast as possible right away. It also means that even in the sim, the rocket drops to sub mach 2 in under a second after burnout.

If I wanted to do hypersonic the “right way”, I would probably stage it on top of some large dumb booster, and use a slower propellant to minimize the drag losses.

 

[StreuB1]

What I am referring to has nothing to do with altitude, breaking up, etc. There is a physical wall between your DUT, and the term hypersonic.

There is also an approach when it comes to exposed frontal area, impulse, and overall velocity.

BTW, why do you and everyone else in a certain group, keep using the term delta v almost ad nauseam? Honest question, because I honestly want to know! Not being mean either!!!

Delta V is when your starting velocity is unknown to the reader. In this case, your starting velocity is implied, as you are on the surface of the earth and not moving relative to the surface of the earth. (IGNORE CORIOLIS!!) Therefore, you can just say velocity. I know Delta V sounds cool and all, but it really isn't and doesn't apply. Delta V is more applicable when it comes to orbital mechanics or where mass or orbital bodies comes into play due to capture and escape velocity.

For instance. Someone designing a tactical missile of some sort (ATGM), or a gun-fired projectile, does not use the term delta V, it is simply velocity. This project, and every project that people would work on within the realm of HPR and slightly beyond, velocity applies.

 

[Brainstormz123]

What I am referring to has nothing to do with altitude, breaking up, etc. There is a physical wall between your DUT, and the term hypersonic.

There is also an approach when it comes to exposed frontal area, impulse, and overall velocity.

BTW, why do you and everyone else in a certain group, keep using the term delta v almost ad nauseam? Honest question, because I honestly want to know! Not being mean either!!!

Delta V is when your starting velocity is unknown to the reader. In this case, your starting velocity is implied, as you are on the surface of the earth and not moving relative to the surface of the earth. (IGNORE CORIOLIS!!) Therefore, you can just say velocity. I know Delta V sounds cool and all, but it really isn't and doesn't apply. Delta V is more applicable when it comes to orbital mechanics or where mass or orbital bodies comes into play due to capture and escape velocity.

For instance. Someone designing a tactical missile of some sort (ATGM), or a gun-fired projectile, does not use the term delta V, it is simply velocity. This project, and every project that people would work on within the realm of HPR and slightly beyond, velocity applies.

I guess the reason for me using the term delta-v instead of raw velocity is because drag is a big part of this rocket. Ive never used it for any hpr rockets before, because its not that big of a deal. In space/without drag, this rocket has around 2860 m/sec of delta v, or enough to go around mach 8.5. Problem with earth being a thing is that there is gravity and drag. So, for the sake of argument assuming fast and slow propellant have the same isp, faster propellant gets you going much faster since drag losses take a massive toll.

Thats the reason for my using of that term in the previous response, but it has almost no real significance to the rocket itself, and is a useless metric imo. I only used it to explain why I choose to use a fast propellant instead of a slower one.

If I had just said “my velocity is 2800 m/sec”, the average person on this forum would say that it makes no sense and could never happen because the term “velocity” doesnt get the point across of potential energy transferred.

But also, would you care to elaborate on this “physical wall” you speak of? Mach 4.99 and 5.01 aren’t particularly different from my understanding.

 

[CarVac]

What I am referring to has nothing to do with altitude, breaking up, etc. There is a physical wall between your DUT, and the term hypersonic.

This is completely pointless advice unless you explain what this "physical wall" actually is and how to avoid it if possible.