Paramotor Thrust and Sound Pressure Level Testing
Pat Barton (not dealer affiliated)
Bruce Brown (Ohio Powered Paragliding)
Mo Sheldon (Airparamo)
Methods:
Fourteen paramotors were tested for static thrust and “loudness” (sound pressure) on between about 2:00
and 3:30 pm Sunday February 8, 2004 at the Paratoys Convention (held at the Salton Sea, CA). Mo
Sheldon directed the thrust testing and provided the thrust test rig that included a commercial quality
digital scale. The scale was zeroed before each thrust measurement. Mo Sheldon and Bruce Brown each
provided a Radio Shack dB (decibel) meter. All data was measured and recorded by Mo, Bruce, Pat
Barton, Francesco “Check” De Santis (Powerglider/U-Can-Fly-2) and Jose Casaudoumecq (Aerolight
USA). Sound pressure levels were made using “A” weighting on the dB meters. The environmental
conditions were approximately 71 degrees F., and 1021 mbar barometric pressure.
Four sound pressure measurements were made on each motor:
1.
Approximate center of the pilot’s head at full power
2.
Approximate center of the pilot’s head with motor producing 50 lb thrust (simulation of
level flight power)
3.
15 feet to starboard and 3 feet forward of the prop hub, 3 feet above ground
4.
15 feet to starboard and 3 feet forward of the prop hub, 3 feet above ground, with motor
producing 50 lb thrust (simulation of level flight power)
It is important to note that the sensitivity of the human ear is in the range of 2-3 dB. In other words, a
sound increasing in loudness from say, 80 to 81 or 95 to 96 dB will generally not be noticeable. A sound
increasing from say, 80 to 83 dB will on the other hand be (just barely) noticeable louder to an average
listener. When evaluating motor “loudness” data, it is practical to say that a difference of 1 or 2 dB
between one motor and another is not significant. A motor that is on average, say 5 or 6 dB “louder” than
another motor is in fact significantly louder, and will be noticed by most listeners. Note that these rough
observations do not, however, address frequency response and the human perception of which sounds
(frequencies) are more pleasing (or displeasing) – these perceptions are quite complicated and to some
extent subjective.
The following is a rough guide to sound pressure in decibels:
120-130 dB
115-125
95-120
80-100
55-75
20-30
threshold of pain and hearing damage (depends on frequency and exposure time)
typical rock concert (front 1/3 of audience)
typical “disco” – on dance floor
typical wedding or small club band
normal conversation (at listener’s ear)
light breeze through tree
Results:
Table 1 presents the thrust results for each motor unit along with prop style and pilot name (owner); these
results are listed from highest to lowest measured thrust. The average thrust for all fourteen motors was
113 pounds (+20). The Simonini powered units generally produced more thrust than the other units, and
if the Simonini motors are removed from the data set, the average thrust for the remaining ten units was
103 pounds (+10).
For each motor unit the four sound pressure measurements were added to yield a “thrust score”: a
simplistic representation of overall motor unit “loudness”. Table 2 presents the sound pressure
(“loudness”) data for each unit, ranked from “quietest” to “loudest” based on the calculated thrust score.
Table 1: Paramotor Thrust Summary
Unit Brand/Model
Prop Type
Thrust
(lb)
Motor
Brand
Pilot/Owner
Walker Jet RR
51” 3-blade comp.
160
Simonini
Dell
Sky Cruiser 200
46” 2-blade wood
138
Simonini
Steve
Fly Power Gold 130
51” 2-blade comp.
133
Simonini
Mo
Fly Power Plus
48” 2-blade wood
124
MZ 34
Dan
Fly Power Gold 115
48” 2-blade comp.
122
Simonini
Javier
Homebuilt
45” 2-blade wood
114
Kaw 80
Alex D
Fresh Breeze 122
48” 2-blade comp.
109
Solo
Hans
Homebuilt
48” 2-blade wood
105
Rotax 125
Alex B
Fly Power Flash
48” 3-blade comp.
100
Sky 100
Javier
SD 48
48” 2-blade wood
98
Solo
Bob
Powerglider Iflyer
49” 2-blade wood
98
Top 80
Check
Fly Power 130
50” 2-blade wood
95
Solo
Pat
MiniPlane 125
49” 2-blade wood
90
Top 80
Scott
Sky Cruiser 100
48” 2-blade wood
93
MZ 100
Tony
Average Thrust
113 + 20
103 + 10 excluding Simoninis
Table 2: Paramotor “Loudness” Summary
Unit Brand/Model
Decibels at Full Power
Pilot’s Head 15 feet
Decibels at 50 lbs Thrust
Pilot’s Head
15 feet
Thrust
Score
Fresh Breeze 122
112
99
100
85
396
SD 48
115
98
99
86
398
Sky Cruiser 100
115
96
103
87
401
Fly Power Flash
116
97
104
86
403
Powerglider Iflyer
116
95
107
87
405
Walker Jet RR
118
105
100
88
411
MiniPlane 125
118
96
108
89
411
Sky Cruiser 200
120
104
106
89
416
Fly Power 130
119
99
109
90
417
Homebuilt - Rotax
119
103
105
90
417
Homebuilt - Kaw
116
103
107
91
417
Fly Power Gold 130
121
106
108
92
427
Fly Power Plus
122
106
107
92
427
Fly Power Gold 115
123
105
111
95
434
Averages
118
101
105
89
413
Standard Deviation
3.1
4.1
3.6
2.8