BARNARD MICROSYSTEMS LIMITED
helping you keep an eye on things...
We have derived data from the open literature for the following UAVs, and used our UAV Analysis Utility to check the consistency and reality of the data. Interestingly, we have found some glaring inconsistencies in the published UAV data, particularly in respect of the suggested range.
- TAM 5
- Aerosonde I
- Shadow 200
- Hermes 180
- Hermes 450
- Predator MQ-1
- Hermes 1500
After checking the data consistency, we derived relationships between UAV parameters based on the above UAVs.
UAV Analysis V1.0
If you plan to use existing data as a basis for trend analysis, it is important to check the consistency of the data first. In particular, the military are often more interested in endurance time, and for them the UAV range is often less important and governed by issues such as Line of Sight (LOS) or limitations on the range of their Command and Control radio links. So, more often than not, the quoted UAV range is far less than the true range cabability of the UAV in the absence of radio link issues.
Note that we have converted a Microsoft EXCEL spreadsheet to an HTML script using the SpreadsheetConverter software, and have incorporated the resultant HTML script in this web page. Consequently, depending on the security setting on your computer, you might be asked whether you would like to allow your computer to run the following HTML script.
I have noticed that the UAV Analysis Utility can become corrupted. If you find it is not working, please drop me an email and I will upload a working copy of the utility. My email address is:
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Select UAV Analysis to call up our UAV Analysis Utility. |
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Version |
Comments |
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1.0 14 May 07 |
Initial software version. |
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UAV Analysis basis |
In this section we discuss the basis for the calculations of the various UAV parameters from input data consisting of:
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Range in Km
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Take-off weight in Kg
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Weight of fuel in Kg, although we do predict the fuel weight)
- Endurance speed in Kph
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1. Wingspan |
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2. Length |
Length = WingSpan / 1.775 = [m]
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3. Airframe weight |
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4. Weight of fuel = Wf |
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5. Characteristic distance " D" |
For a flight at constant speed, we have assumed the power required to keep the plane moving is directly proportional to the total weight of the plane, which decreases in a non-linear manner with time as the fuel is used up. The weight of the plane at a distance = x is given by W(x) = Wto * exp( - x / D ), where Wto is the take-off weight of the plane, and D is a figure-of-merit for the plane we call the " characteristic distance" . Through a simple integration, it can be shown that:
D = R / ln (Wto / Wnf)
where R is the range, Wto is the take off weight and Wnf is the weight of the of the plane with no fuel on board. For simplicity, it is assumed that at the end of the UAV flying a distance = R, there is no fuel left on the UAV.
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6. Endurance |
Endurance = Range / EnduranceSpeed = [hours]
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7. Maximum engine power |
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8. Engine capacity |
For a four stroke engine, Pout = 0.073 * x + 0.031 for Pout in KWatts, where x is the engine capacity in cc. The engine capacity = CAP is given by:
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CAP = (Peng_max - 0.031) / 0.073 = [cc] |
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Peng_end = power of the engine at endurance speeds in KWatts
- See 4 stroke engines section for details.
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9. Engine weight |
- For a 4 stroke engine, the power-to-weight ratio = Rptw = 1.814 KW / Kg
- See 4 stroke engines section for details on four stroke engines.
- For a Wankel engine, the power-to-weight ratio = Rptw = 2.3 KW / Kg
- See Wankel engines section for details on Wankel engines.
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Engine weight = Weng = Peng_max / Rptw = [Kg] |
- Weng = weight of the engine in Kg
- Peng_max = the maximum engine power in KWatts
- Rptw = the power-to-weight ratio for the engine in KWatts / Kg
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10. Payload weight |
payload weight = Wpl = Wto - Waf - Wf - Weng
- Wto = takeoff weight
- Waf = airframe weight
- Wf = weight of fuel
- Weng = weight of the engine
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