OPEN ROCKET ROCKET GRAPHIC ERROR

[Black Sea Rocket]

ROCKET RETURNS ON THE DISTANCE GRAPH, IS IT RELATED TO THE BENEFICIAL LOAD? I DID NOT FIND THE ERROR

 

[smstachwick]

View attachment 501790




ROCKET RETURNS ON THE DISTANCE GRAPH, IS IT RELATED TO THE BENEFICIAL LOAD? I DID NOT FIND THE ERROR

It’s not an error. Rockets tend to fly into the wind when they launch, this is called weathercocking. Then they get blown downwind after deployment, sometimes passing directly over the pad if the wind direction aloft is consistent enough and then even further downrange.

You may get more useful data plotting both parameters against the flight time, however.

 

[Black Sea Rocket]

It’s not an error. Rockets tend to fly into the wind when they launch, this is called weathercocking. Then they get blown downwind after deployment, sometimes passing directly over the pad if the wind direction aloft is consistent enough and then even further downrange.

You may get more useful data plotting both parameters against the flight time, however.

Thank you for your answer, I will be careful

 

[manixFan]

I would think a big concern of that graph is the amount of weathercocking shown by the plot. It implies a very overstable rocket or underpowered for the wind conditions. The horizontal velocity will likely be quite high at apogee deployment, which can cause issues. It shows dual deployment, but even still any high speed deployment can be problematic. Look at the 'Velocity at deployment' value and verify that it is not higher than you'd like.


Tony

 

[smstachwick]

I would think a big concern of that graph is the amount of weathercocking shown by the plot. It implies a very overstable rocket or underpowered for the wind conditions. The horizontal velocity will likely be quite high at apogee deployment, which can cause issues. It shows dual deployment, but even still any high speed deployment can be problematic. Look at the 'Velocity at deployment' value and verify that it is not higher than you'd like.


Tony

A basic online right triangle calculator gives a 73° elevation angle from the launch pad at apogee, equating to 17° from vertical at apogee.



I believe that RockSim determines any flight that stays within a 40° cone (20° on either side when viewed as a cross section) to be safe. This flight might raise a few hairs but I wouldn’t call the weathercocking an excessive hazard.

Deployment velocity might be worth looking into, though.

 

[manixFan]

A basic online right triangle calculator gives a 73° elevation angle from the launch pad at apogee, equating to 17° from vertical at apogee.

View attachment 502201

I believe that RockSim determines any flight that stays within a 40° cone (20° on either side when viewed as a cross section) to be safe. This flight might raise a few hairs but I wouldn’t call the weathercocking an excessive hazard.

Deployment velocity might be worth looking into, though.

I'm not sure what you are trying to say here. The rocket weathercocks nearly 1/3rd of its altitude, which I think will lead to excessive deployment velocity. I've been burned on numerous occasions by this very type of flight profile before I started paying attention to it. I didn't call the safety of the flight into question, other than as it relates to depoyment velocity. Which is exactly what you say is worth looking into.

So you seem to be disagreeing with my post while agreeing with my only point?


Tony

 

[smstachwick]

I'm not sure what you are trying to say here. The rocket weathercocks nearly 1/3rd of its altitude, which I think will lead to excessive deployment velocity. I've been burned on numerous occasions by this very type of flight profile before I started paying attention to it. I didn't call the safety of the flight into question, other than as it relates to depoyment velocity. Which is exactly what you say is worth looking into.

So you seem to be disagreeing with my post while agreeing with my only point?


Tony

Sort of, but I think I should explain my line of thinking.

The line on the original graph isn’t to the same scale on both axes. In other words, it’s not a literal depiction of the rocket’s flight path and weathercocking angle. I ran a few numbers and attached my own image of a better-scaled diagram for additional clarity on this point.

With that result in hand, it doesn’t look to me like a shredded parachute or, god forbid, a lawn dart, will necessarily pose a danger to those outside the boundaries of the range. Obviously this depends on the particulars of the range, though. This sort of hazard would be very worthy of consideration at a smaller field, but one waivered to around 14,500 ft like ROC’s site, for example, might be large enough to keep a flight like that on the field.

However, it’s still a good idea to check the deployment velocity to ensure minimal risk to those who are actually on the range, perhaps recovering their own rocket.

That’s all I’m trying to get at here. Making sure the visuals aids are clear and the specific natures of the potential risks are clearly identified.

 

[manixFan]

I can read graphs just fine, and was only ever concerned about the deployment velocity. The graph makes it clear it is weathercocking nearly a full kilometer, I was not worried about the shape of a triangle.

You agree with my original premise that deployment velocity is worth a look. That's all I was trying to say, nothing more.


Tony

 

[smstachwick]

You’re manufacturing imaginary conflict out of an attempt to provide additional clarity.

UPDATE: Apologies for the attitude, it can be difficult for me to read intent through a computer screen. Your updated post is clearly not as argumentative as I had interpreted the original version to be.

 

[manixFan]

I just was having a hard time understanding your posts. I don't see that as a conflict, but rather trying to understand the point of the triangle relating to my concern of deployment speed.

I'm sorry you saw my attempts to clarify your points as a conflict, I was just trying to figure out what you meant.


Tony

I agree completely, intent does not carry through the screen, it's much ado about nothing, sorry for the fuss!!