Sponsored by: Atsko Products, Swhacker Broadheads, & C’Mere Deer Products
By: bowhunting biologist Wade Nolan
We took the Swhacker flight stability testing to a new level at major University. Working in the Aerospace lab we focused on the water channel where missiles and wing designs are tested. Could this testing tell us why some broadheads fly like field points and others like paper airplanes? Is this level of testing over the top for a broadhead? Or, are bowhunters looking for a broadhead that would pass missile flight criteria? How important is accurate?
The water channel tank is a circular design where the water is propelled at a known rate. Both water and air act the same when contacting a surface but because water is so dense it's flow pattern is observable to the naked eye. Another benefit of water channel testing is that the pressures of the water's force on a wing or fin is much easier to measure than that of air. Prior to this testing expedition I didn't even know that a water channel is how ballistic missile designs are first tested and perfected.
If you want to go all the way to the edge in testing you enter a room like this one.
Water channels are only found in aerospace testing facilities.
Real missiles are tested via computer flight programs and through computational methods prior to a launch.
Author examines the jet propulsion lab testing facility.
There is another department at this university that is often used for classified testing. They are often contracted by missile manufacturers to conduct aerodynamic testing at supersonic wind speeds. We will move to the wind tunnel eventually, but first we must do baseline testing in the water channel.
Wind tunnels are a huge expense to develop and maintain but they offer the final level of testing prior to a real launch. We bring the Swhacker into the wind tunnel in future testing.
In the wind tunnel, at Mach.7, the results are only observable with a high-speed camera and then only for a fraction of a second. Eyeballs tell the story in the water channel.
This is how it works. Motors within the water channel circulate the water at a known speed, then we introduce a UV-dye under a black light upstream of the test missile to observe the currents and disturbances made by the water as it flows over the test subject.
Note dye pattern as it travels over the Delta wing.
This is the delta wing design that our most sophisticated bombers rely on. Look at the vortex of dye above the wing. This demonstrates lift and stability.
Aerospace computer programs interpret data gathered from sensors.
We attach micro sensors to the test apparatus to measure lift, drag and yaw. The sensors are managed via a computer program.
We are looking for stable flight. The flat lines on the readout tell us that this test is a good one.
During testing, we tested a life-size Swhacker against another popular open on contact broadhead. Although the difference was small, it was measurable. Flight stability relates directly to the Science of Accuracy.
The aerospace professor suggested that the best results are gathered when you test a scale model….so we contracted that one be made by their prototyping department. Our model is 800% of life-size. We also had a model of a field point made so we could test the performance of the Swhacker against the field point.
Our model may be the largest scale model broadhead ever made.
This big Swhacker is a test prototype the size of military missiles. It will give us real results.
We made a scale prototype of a Swhacker and mounted it on a facsimile arrow shaft. We introduced dye to see if it disturbed the current flow. It didn't and the dye followed down the shaft undisturbed. As expected, low drag and the dye following the shaft, back indicates that the field point is not causing an air disturbance as it flies. That is why field point accuracy is the standard.
The UV dye travels across the exposed surfaces of the Swhacker and hug the shaft. The dye pattern is free of vortexes and swirls. This is what makes a broadhead fly true.
Next, we attached the Swhacker to the probes and sensors and exposed it to the moving water. Then we introduced the dye…Stable flight was the result. Not a big surprise considering a bowhunting rocket Scientist designed the Swhacker.
Note how the dye follows the shaft. The dye above and to the rear is excess dye pumped in during the test.
What does all of this science mean to you? It means we've done our homework. Swhacker offers accuracy you can see and rely on. The accuracy that we see in the aerospace testing lab is the same accuracy the Swhacker delivers in the whitetail woods.
Like to enter the actual lab and watch the testing? Click Here - Aerospace Accuracy
For more please go to: Swhacker Broadheads
And: Wade Nolan's Whitetail University