On 10-6-2006 and 10-7-2006, with the permission of the owner, we took audio measurements of the portable vertical wind tunnel VR Skydive, which was located about 1/2 mile from Appalachian Amusement Center. These measurements are provided here as a comparison to demonstrate how quiet the L-1 design is compared to a typical portable VWT.
This is the fourth portable VWT I have flown in and I do not think it is any louder than the others. At the time of these measurements the machine was at flight speed, but the exact power setting was not known. The airspeed at the time of the tests was approximately 115-115 MPH, which is probably approximately 75-85%. Care was tasken to make the measurements when the machine sounded to be at higher power and not when it was throttled down for a smaller person. This machine is very fast at the expense of diameter. It has a 1200 horsepower Diesel engine.
There was intermittent wind on the second day. Care was taken to make the measurements between gusts. The wind did not effect the measurements.
On 10-6 I took one measurement, at approximately 65 feet from the machine, in it's 10:30 position. This was at approximately 4:30 PM local time. The weather conditions as measured at AAC were 60 F., 8-13 MPH wind, 56% RH, and a barometric pressure of 30.07.
The remainder of the measurements were made on 10-7-06. The measured conditions this day were 61 F., 57% RH, and a BP of 30.97. The distances this day were measured from the meter to the prop hub using a Simmons Yardage Master 1000 laser range finder. Measurements this day were taken from about 3 to 4 PM. Click the boxes below to see measurements tasken at these distances.