Ping Pong Parachute B/C

[sciolyperson1]

How many cords did you guys put on your parachute? What is a good number?

I'm still deciding on the best number of cords. Honestly, they can range anywhere from 8 to 16. Tangling will be an issue no matter how many cords you put on, so more cords are probably better overall. I'm not sure if this is scientifically correct, but I believe more cords would allow the parachute to open up more than less cords would allow.

You're correct. Just wanted to add that the more cords you add the heavier it is, so avoid going too overboard with them. 8-16 seems like a nice range.

[eagerlearner102]

How are you guys using tape to attach your ping pong balls? I was thinking of putting some hook and string, but that was more of a random idea.

[CookiePie1]

I think I would use a thin strip of electrical tape and attach the threads of the parachute directly to the ball to save weight.

[gruvint8]

Hey, I have a question about the parachute materials. So someone suggested that we try to use regular cloth for the actual parachutes, and I'm not too sure about the idea, nor is my partner on the event. My initial thoughts are that I am wondering if A) the cloth will not resist air as much as plastic due to the small holes around the individual threads spread around the parachute and B) perhaps those holes won't effect the drop time at all unless there is a certain amount of weight pulling on it. Of course, I'm no physicist so these are just initial thoughts that I pondered, does anyone have any information regarding the idea? If not, we can test the material for parachutes and report our discoveries afterwards to those who may be interested in the subject.

[sciolyperson1]

Hey, I have a question about the parachute materials. So someone suggested that we try to use regular cloth for the actual parachutes, and I'm not too sure about the idea, nor is my partner on the event. My initial thoughts are that I am wondering if A) the cloth will not resist air as much as plastic due to the small holes around the individual threads spread around the parachute and B) perhaps those holes won't effect the drop time at all unless there is a certain amount of weight pulling on it. Of course, I'm no physicist so these are just initial thoughts that I pondered, does anyone have any information regarding the idea? If not, we can test the material for parachutes and report our discoveries afterwards to those who may be interested in the subject.

A) You are correct, cloth does not contain air very well. Because there are holes, times would be affected significantly.

Just want to add, since cloth is extremely heavy (compared to other materials), the parachute would likely collapse in on itself really quickly after deployment

[xiangyu]

First of all, thanks to everyone who has given me some ideas with parachutes, Our parachutes are working much better (around 10 seconds and continuing to improve in ~25 feet height.

Now, my team is encountering another problem. We are having touble with parachute detachment from the rocket. We've tried different designs like tube on top of rocket to hold ping pong or just launching parachute on bottle or inside nose cone, but still we just can't consistantly ensure parachute detachment. What are y'all using? Any tips/design ideas? I know you may want to keep some things secret, but any help would be greatly appreciated!

Xiangyu

[kkgppp]

What qualifies as the nose? Other than the blunt top are there any other limitations on size, shape, etc? Do you all know? Does the payload (parachute) have to be inside the nose? Can the nose have two pieces or does it have to be a single entity?

[kkgppp]

d.The nose of the rocket must be rounded or blunt at the tip and designed such that when a standard bottle cap (~3.1 cm
diameter x 1.25 cm tall) is placed on top of the nose, no portion of the nose touches the inside top of the bottle cap (see
Figure 1).

To satisfy this rule, can the ping pong ball be the top-most rounded portion of the rocket but then detach? Otherwise, if the top of the rocket is blunt, how does one attach the ping pong ball?

But based on rule 5c:

c. When called to launch, teams will load their rocket onto the launcher. Once the rocket is loaded, but
NOT pressurized, teams will place the parachute payload system on or in the rocket. After the payload
parachute system is loaded it cannot be manipulated.

So it seems like the ping pong ball is separate from the rocket in which case it seems like the rocket itself needs a blunt nose apart from the ping pong ball?

It appears there are 3 distinct parts - the rocket pressure vessel, the rocket with the nose cone, and the parachute/payload which can be inside the nose cone or outside... is this how others are interpreting the rules? Also, can the nose cone fall off without the whole rocket having to fall off from the pressure vessel to release the parachute?

[CookiePie1]

Winning time @ UGA was 7.88 seconds. Makes sense from my experience at NJ states 2 years ago. not sure about the celing height. Pressure at NJ states was fixed at 40 psi.

[sciolyperson1]

Time predictions? For liso (18.5ft), I'd say 8 seconds would get top 6, 20 seconds winning?