Help with science project to launch a projectile

[erobz]

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?

 

[SSKscioly]

24 inches

 

[erobz]

24 inches

Then what is the internal volume of the barrel?

 

[SSKscioly]

42.41 cubic inches

 

[erobz]

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.

 

[hutchphd]

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!!

 

[SSKscioly]

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.

 

[SSKscioly]

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)

 

[hutchphd]

Do you have actual data (as requested)?