Cold weather operations for paramotors

by Had Robinson
updated February 15, 2020

Cold weather operations (<15C/60F) require a perfectly operating fuel system and ignition (including possible modifications to the carburetor).  The correct fuel-air ratio must be maintained and enough fuel must be delivered to the engine.  The correct type of inline fuel filter should also be used and the pickup tube filter in the tank (if there is one) may need to be modified.

Pilots operating in very cold conditions (<0C/32F) can add a carburetor pre-heat system.  This greatly helps fuel vaporization as well as lowering the density of the air and viscosity of the fuel entering the engine.

Before modifying anything in the fuel/air delivery systems or checking the items below, perform a thorough fuel system test on the engine.  It is a waste of time if this test not done.

Cold weather increases the density of a gas and the viscosity of a fluid.  This means that air, gasoline, and oil move through the same sized pipe/tube, filter, or screen more slowly as the temperature decreases.  Thankfully, restrictions in air flow through the engine is not a problem.  However, adequate fuel and oil delivery is a serious issue as the temperature drops.  This is mostly due to the inherent problems with the fuel pump design in the WG and WB series carburetors and the presence of a very fine inlet filter screen in these carburetors.  Cold air has a higher density and, accordingly, requires more fuel to burn to prevent the mixture from being too lean.

Here are things to check when operating when it is cold (<15C/60F).  The colder it is, the more pronounced the problems are and the more likely a lean condition will be experienced.  It is good news that a lean condition is less likely to cause overheating of the engine.

Note that the optimal propeller pitch in warm ambient conditions (22C or 72F) is different than at freezing temperatures (less pitch is required).

I am continually testing paramotors in all sorts of conditions and will post new information on these pages.

Turkey Vulture

USHPA
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