Help with science project to launch a projectile

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Homework Help Overview

The discussion revolves around a high school science project involving the launch of a projectile using a drop tower mechanism. The original poster is attempting to achieve a launch distance between 2 and 8 meters with a ping pong ball, but is consistently unable to exceed 5 meters, despite using different weights for the piston.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants explore the relationship between the mass of the piston and the launch distance, questioning why a heavier mass does not yield greater distance. There are suggestions to vary the angle of projection and to investigate the dynamics of the piston and projectile interaction. Some participants also discuss the potential impact of air leaks and friction within the launching mechanism.

Discussion Status

The discussion is ongoing, with various participants providing insights and suggestions regarding the mechanics of the launch system. There is no explicit consensus, but several lines of inquiry are being explored, including the effects of mass, air pressure, and sealing techniques.

Contextual Notes

The original poster has noted constraints regarding the competition rules, including the need for the projectile to reach a minimum distance of 8 meters, and the uncertainty of target placement until shortly before the event. There are also mentions of sealing methods and the construction of the piston, which may affect performance.

  • #31
SSKscioly said:
Hi @ erobz ,

The total volume of the barrel is 301.59 cubic inches ( 24 inches height and 4 inch diameter)

The sealed chamber is 9 inches down from where the holes to the top of the weight when it is dropped , so if I am calculating correctly, my internal working volume is 113.10 cubic inches
Your barrel is 1.5 inch diameter. What is its length?
 
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  • #32
24 inches
 
  • #33
SSKscioly said:
24 inches
Then what is the internal volume of the barrel?
 
  • #34
42.41 cubic inches
 
  • #35
You are trying to figure out where the red dashed line is. That is the line you should not drill holes below. You are doing that by comparing the volume inside the barrel, to the volume inside the tower between those lines. we need enough air inside the sealed part of the tower to completely displace the air in the barrel.

1699989582768.png
 
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  • #36
I would leave some undrilled space to allow some compression in the barrel air as well as some space for the seals on the weighted puck to work so the hole terminus line seems about correct to me...... we need data!!
 
  • #37
hutchphd said:
I would leave some undrilled space to allow some compression in the barrel air as well as some space for the seals on the weighted puck to work so the hole terminus line seems about correct to me...... we need data!!
Thank you hutchphd, I am going to work on collecting the data over the weekend.
 
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  • #38
Hi @hutchphd , @erobz , I am able to solve the long range issue. I changed the connectors from the tower to the barrel to 2 inch ones ( they were 1.5 inch before) , the projectile now shoots 8m. I am dropping the 3 kg weight from the height of 24 inches in to the 4 inch tower with no holes. The barrel is still 1.5 inch pipe and 24 inches long.

However when i tried testing the near target ( around 2 m distance) by dropping the weight half way through the 4 inch pipe the ball doesn't shoot out of the barrel at all. It keeps rotating inside the 2 inch connectors. If i try changing to 1.5 inch connectors , i am back to 5-6 m range.I tried replacing the 4 inch pipe with the one that has holes and the range is really bad ( only 2 meters)
 
Last edited:
  • #39
Do you have actual data (as requested)?
 

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