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It has come to my attention that there is a misinterpretation of some torque meter readings.

It is important to understand YOUR torque meter output scale, and whether it is calibrated and in what units. Some low-cost meters are arbitrary numbers and not in any traditional units. In addition, some low-cost meters have approximate oz-in, but are not calibrated. These are all OK in your data, comparing flight to flight. However, it you compare to others, you need to know actual torque values.

The meter in question was the IFFS meter, a very expensive and precision instrument. The user felt it was off by 30%. However, while the precision and repeatability is there, it is important that the dial indications are NOT oz-in, but arbitrary units. This is because the meter is sold with one of three different interchangeable elements. These elements are precision, and the output should be considered accurate. The meter comes with instructions and a table that converts the reading to oz-in depending on the element installed. The table is also available on the IFFS website.

I believe the FFM and J&H meters are approximate oz-in, close enough to compare.

The IFFS low=cost torque meter (Team Fund Raiser) is also very close.

The IFFS precision torque meter, as noted above, has arbitrary units on the dial which must be converted based on which element is installed.

The Laser Cut Planes meter is arbitrary. It should be approximately 0.47 oz-in for 180 degrees of deflection.

Note also that some low cost torque meters have very short elements, and as such may be permanently deformed if rotated a full turn. A 4-5" element probably falls in this category, depending on the element diameter. A 9" element with 2 oz-in for a full turn should be OK with up to a full turn. Note: The J&H meter appears, based on Josh's video, to have oz-in markings, with 1.0 for a full revolution, and the listing indicates it is good for up to 1.5 oz-in, so it appears his element is good to that point.

Coach Chuck

Hey Coach Chuck!

What torque should I got for with this years division B rules. My kit is "stinger" and im using the Ikara 24cm propeller and stock rubber.

Your torque will depend on the actual width (or linear density) of rubber used. "Stock" does not indicate what width you have. But, generally for the SO rubber this year your peak torque may be in the 1.2-1.6 oz-in range.

You then unwind to a launch torque that depends on your plane design, trim, and ceiling height. For normal school gym ceilings you will likely be between 0.3 and o.6 oz-in launch torque. That is a wide range, but there are many variables. This is where test flying comes in.

This is NOT a build event. Rather, it is a flight optimization event. The build itself is relatively minor compared to the effort involved in trimming and then optimizing your flight. A big part of optimization, after basic trim, is the matching if prop, rubber, and launch torque.

Coach Chuck