5 replies to this topic

[KaptainKrazy]

I was wondering what different shapes of dart heads will do to affect the airflow around dart. Here is a few diagrams:

Air Pressure Around a Glue Dome Stefan (Red is high pressure, blue is low)



Air Speed Around a Glue Doem (Red is faster, blue is slower)



Air Pressure Around Slug Dart



Air Speed Around Slug Dart



Air Pressure Around Theoretical Pointy Dart



Air Speed Around a Theoretical Pointy Dart




Feel free to comment things you want me to test, or maybe your observations.

[Insan3 Crab]

Is this a computer program? And why is the first dart flattened on one side?

[Aeromech]

'Insan3 Crab', on 19 Feb 2012 - 11:40 PM, said:

Is this a computer program?

What software is this? And why do the darts appear as though they were drawn in MS paint?

[KaptainKrazy]

'Insan3 Crab', on 19 Feb 2012 - 11:40 PM, said:

Is this a computer program? And why is the first dart flattened on one side?

'Aeromech', on 20 Feb 2012 - 12:08 AM, said:

What software is this? And why do the darts appear as though they were drawn in MS paint?

Insan3 Crab, it's an iPad app.

Aeromech, because its drawing capabilities are very limited.

[Doom]

Nice work KaptainKrazy. This is good for a qualitative study. I think Landru posted something similar a few years back, but I can't find it.

The iPad app is called Wind Tunnel.

Unfortunately, most CFD programs (like this) are inadequate for simulating Nerf dart trajectories. I'm assuming based on your photos that this program simulates incompressible 2D flow around objects without any turbulence models. Incompressible is okay, but 2D is not, especially without a turbulence model. Darts also can flap around, and a CFD model like this doesn't account for that. The drag in this case is probably very different from the drag in a real case.

Testing is the best way to determine the performance of Nerf darts. Get a chronometer, a measuring tape, and do some range tests (trying to avoid wind while you're at it). This'll tell you more.

[Exo]

"We" don't make pointy darts because they are pointy.

A well made hotglue dome is aerodynamic enough for our purposes, but if you wnat something standardized, check out TaerKitty's NutHeads

Edited by Exo, 20 February 2012 - 10:04 AM.