Overview
The First Step to Optimizing Performance — Knowing the current environmental conditions can often be the difference between finishing in the money and just finishing.
Even slight changes in air density, water grains, and density altitude can dramatically affect a machine’s performance. With the added ability to easily measure and track these and other critical factors, such as absolute pressure, temperature, humidity, wind speed and barometric pressure, the Kestrel 4250 Racing Weather Tracker arms racers with the accurate weather data needed to make those last minute jetting or tuning decisions.
Real-Time Data
Conditions on the track can often vary greatly from those in the pits. The rugged, portable and easy to use Kestrel 4250 Racing Weather Tracker quickly provides racers and pit crews with the most accurate and up-to-date data available where you need it most — at the track. It allows tuners to determine what last minute changes need to be made based on the current local conditions, even immediately before the first lap around the track or pass down the drag strip — giving you that competitive edge at a fraction of the cost of other systems on the market.
Data Logging
The Kestrel 4250 Racing Weather Tracker also features an automatic and manual data storage function, allowing you to easily keep logs of race day conditions from track to track, year to year. The Kestrel PC Interface and Communicator Software allows data to be easily transferred directly to a PC or laptop making long-term storage, in-depth analysis, and detailed charting of stored data a breeze.
Kestrel 4250 Measures
Density altitude
Water grains / moisture content
Air density
Station pressure
Relative air density
Humidity
Wind speed
Temperature in °F or °C
Kestrel 4250 Features
Waterproof and floats
Backlight for low light conditions
Data logger (automatic and manual)
Customizable data storage – 3200 data points
Multi-Function 3-line display
Convenient averaging mode
Data charting
Humidity sensor can be recalibrated in the field with our Relative Humidity Calibration Kit.
User-replaceable impeller
Flip-top impeller cover
Upload to a computer (with optional interface)
Five languages (English, French, Spanish, German, and Italian)
US Patent Nos. 5,783,753 and 5,939,645 and 6,257,074
5-year warranty
Assembled in the USA
Kestrel 4250 Includes
Soft carry pouch
Neck lanyard
Batteries – 2 AAA
Kestrel Certificate of Conformity
Specifications:
| MeasurementResponse Time |
Units |
Operational Range |
Resolution |
Accuracy (+/-) |
|
| Wind Speed1 second |
m/s |
0.4 to 60.0 m/s |
0.1 |
Larger of 3% of reading or least significant digit |
0.4 to 40.0 m/s |
| ft/min |
59 to 11,948 ft/min |
1 |
59 to 7877 ft/min |
||
| km/h |
1.0 to 218.0 km/h |
0.1 |
1.0 to 144.0 km/h |
||
| mph |
0.8 to 135.0 mph |
1 |
0.8 to 89.0 mph |
||
| knots |
0.6 to 118.3 kt |
0.1 |
0.6 to 78.0 kt |
||
| Beaufort |
0 to 12 B |
0.1 |
0 to 12 B |
||
| 1 inch diameter impeller with precision axle and sapphire bearings. Off-axis accuracy -1% @ 5º off-axis; -2% @ 10º; -3% @ 15º. Calibration drift < 1% after 100 hours use at 16 MPH / 7 m/s. Sustained operation above 60 MPH / 27 m/s will wear impeller ra |
|||||
| Temperature1 second |
°F |
-49.0 to 257.0 °F |
0.1 |
|
-20.0 to 158.0 °F |
| °C |
-45.0 to 125.0 °C |
0.1 |
|
-29.0 to 70.0 °C |
|
| Measures air, water and snow temperature. Thermally isolated, hermetically sealed, precision thermistor mounted externally (US Patent 5,939,645). Calibration drift negligible. |
|||||
| Relative Humidity1 minute |
%RH |
0.0 to 100.0 % |
0.1 |
3.0 %RH |
5.0 to 95.0 % non-condensing |
| Polymer capacitive humidity sensor mounted in thin-walled chamber external to case for rapid, accurate response (US Patent 6,257,074). (To achieve stated relative humidity accuracy, unit must be permitted to equilibrate to external temperature when expos |
|||||
| Pressure1 second |
inHg |
0.3 to 32.5 inHg |
0.01 |
0.05 inHg |
At 77.0 °F, 22.1 to 32.5 inHg |
| hPa / mb |
10.0 to 1100.0 hPa / mb |
0.1 |
1.5 hPa / mb |
At 25.0 °C, 750 to 1100hPa / mb |
|
| PSI |
0.15 to 16.0 PSI |
0.01 |
0.02 PSI |
At 77.0 °F, 10.9 to 16.0 PSI |
|
| Monolithic silicon piezoresistive pressure sensor with second-order temperature correction. Maximum error over temperature range 32 to158 °F (0 to70°C) , +/- 0.06 inHg / +/-2.0 hPa. Calibration drift typically -0.03 inHg / -1.0 hPa per year. Pressure sen |
|||||
| Altitude1 second |
ft |
-6000 to 30000 ft |
1 |
|
At 77.0 °F, <19,700 ft. Max error +/- 98 ft |
| m |
-2000 to 9000 m |
1 |
|
At 25.0 °C, <6,000 m. Max error +/- 30 m |
|
| Temperature compensated pressure (barometric) altimeter. |
|||||
| Wind Chill1 second |
°F |
0.7 to 135.0 MPH, -49.0 to 257.0 °F |
0.1 |
|
1.8 to 89.0 mph, -50.0 to 50.0 °F |
| °C |
0.4 to 60.0 m/s, -45.0 to 125.0 °C |
0.1 |
|
0.4 to 40 m/s, -45.6 to 10.0 °C |
|
| Calculated from the primary measurements of wind speed and temperature. Utilizes the NWS Wind Chill Temperature (WCT) Index, revised 2001, with wind speed adjusted by a factor of 1.5 to yield equivalent results to wind speed measured at 10 m above ground |
|||||
| Heat Index1 minute |
°F |
0.0 to 100.0 %RH, -49.0 to 257.0 °F |
0.1 |
|
70.0 to 130.0 °F, 0 to 100% RH |
| °C |
0.0 to 100.0 %RH, -45.0 to 125.0 °C |
0.1 |
|
21.1 to 54.4 °C, 0 to 100 %RH |
|
| Calculated from the primary measurements of temperature and relative humidity. Utilizes the NWS Heat Index (HI) tables. (Specification temperature limits established by HI tables.) |
|||||
| Dewpoint1 minute |
°F |
0.0 to 100.0 %RH, -49.0 to 257.0 °F |
0.1 |
|
-20.0 to 158.0 °F, 20.0 to 95.0% RH |
| °C |
0.0 to 100.0 %RH, -45.0 to 125.0 °C |
0.1 |
|
-29.0 to 70.0 °C, 20.0 to 95.0 %RH |
|
| Calculated from the primary measurements of temperature and relative humidity. Temperature to which the air would need to be cooled at a constant pressure to become saturated. |
|||||
| Wet Bulb Temperature1 minute |
°F |
-49.0 to 257.0 °F, 0.0 to 100.0 %RH, 8.86 to 32.48 inHg |
0.1 |
|
32.0 to 100.0 °F, 5.0 to 95.0% RH, 8.86 to 32.48 inHg, <19700 ft |
| °C |
-45.0 to 125.0 °C, 0.0 to 100.0 %RH, 300.0 to 1100.0 hPa |
0.1 |
|
0.0 to 37.8 °C, 5.0 to 95.0 %RH, -2000.0 to 9000.0 hPa, <6000 m |
|
| Calculated from the primary measurements of temperature, relative humidity and pressure. Temperature indicated by a wet bulb psychrometer. |
|||||
| Density Altitude1 second |
ft |
-49.0 to 257.0 °F, 0.0 to 100.0 % RH, 8.86 to 32.48 inHg |
1 |
246 |
32.0 to 100.0 °F, 5.0 to 95.0 %RH, 8.86 to 32.48 inHg, <19700 ft |
| m |
-45.0 to 125.0 °C, 0.0 to 100.0 %RH, 300.0 to 1100.0 hPa |
1 |
75 |
0.0 - 37.8 °C, 5.0 to 95.0 %RH, -2000 to 9000 hPa, <6000 m |
|
| Calculated from the primary measurements of temperature, relative humidity and pressure. Air density converted to equivalent sea level elevation at the International Standard Atmosphere. |
|||||
| Air Density1 minute |
lb/ft3 |
-49.0 to 257.0 °F, 0.0 to 100.0 % RH, 8.86 to 32.48 inHg |
0.001 |
'+/-2% |
32.0 to 158.0 °F, 5.0 to 95.0 % RH, 22.10 - 32.48 inHg |
| kg/m3 |
-45.0 to 125.0 °C, 0.0 to 100.0 %RH, 300.0 to 1100.0 hPa |
0.001 |
'+/-2% |
0.0 - 70.0 C, 5-95%, 750-1100hPA |
|
| Calculated from the primary measurements of temperature, relative humidity and pressure. |
|||||
| Relative Air Density1 minute |
% |
-49.0 to 257.0 °F, 0.0 to 100.0 % RH, 8.86 to 32.48 inHg |
0.1 |
+/-2% |
32.0 to 158.0 °F, 5.0 to 95.0 % RH, 22.10 - 32.48 inHg |
| Calculated from the primary measurements of temperature, relative humidity and pressure. |
|||||
| Moisture Content (Water Grains)1 minute |
gpp |
0.000 to 5000.0 gpp |
0.1 |
typical accuracy 10% |
-20 to 130°F, 5 to 95% RH, 8.86 to 32.48 inHg |
| g/kg |
0.00 to 720.0 g/kg |
0.01 |
typical accuracy 10% |
-29 to 54°C, 5 to 95% RH, 300.0 to 1100.0 hPa |
|
| Calculated from the primary measurements of temperature, relative humidity and pressure. The measure of Grains/lb of dry air, called the humidity ratio, is an indication of the mass of water vapor in air. |
|||||
| Max/Avg Wind Speed, Crosswind, Headwind/Tailwind |
One-button clear and restart of Max Wind Gust and Average Wind measurement. |
||||
| Data Storage / Display |
Minimum, maximum, average and logged history stored and displayed for every measured value. 3200-point data logger with graphical display. Auto data storage; interval settable from 2 seconds to 12 hours. Manual data capture. |
||||
| Data Upload |
Requires optional PC interface (NK PN-0830) and provided software. RS-232 connection with USB adapter available. |
||||
| Display |
Multifunction, multi-digit programmable dot-matrix display. |
||||
| Display Update |
1 second. |
||||
| Display Backlight |
Choice of aviation green or visible red electroluminescent backlight. Automatic or manual activation. |
||||
| Clock / Calendar |
Real-time hours:minutes:seconds clock, calendar, automatic leap-year adjustment. |
||||
| Operational Temperature Range(LCD and Batteries) |
The operational temperature range of the liquid crystal display and batteries is 14° F to 131° F / -10 °C to 55 °C. Beyond the limits of the operational temperature range, the unit must be maintained within range and exposed for minimum time necessary to |
||||
| Storage Temperature |
|
||||
| Auto Shutdown |
User-selectable: 15 or 60 minutes with no key presses or disabled. |
||||
| Languages |
English, French, German, Italian, Spanish. |
||||
| Certifications |
CE certified. Individually tested to NIST-traceable standards (written certificate of tests available at additional charge). |
||||
| Batteries |
AAA Alkaline, two, included. Average life, 400 hours of use, +/-depending on backlight use. |
||||
| Environmental |
Waterproof (IP67 standard). Drop-tested (MIL.STD.810F; unit only. Substantial impact may damage replaceable impeller.). |
||||
| Dimensions |
Unit 5.0 x 1.8 x 1.1 in / 12.7 x 4.5 x 2.8 cm. |
||||
| Weight |
Unit 3.6 oz / 102 g. |
||||
| Kestrel Meters are designed and manufactured at NK’s facility in Boothwyn, Pennsylvania, and are individually calibrated at the time of manufacture. Every Kestrel Meter comes with a Certificate of Conformity to document the unit’s accuracy—all Kestrel measurements are traceable to the National Institute of Standards and Technology, ensuring the highest level of reliability. AdditionalNIST Calibration and Certification servicesare available. |
|||||
Producing Area：USA