Originally Posted by green granite
I find that odd, back in the late 60's or early 70's (can't remember exactly) I did a long series of trials @ Waddington & Scampton doing just that with all RAF aircraft. The aircraft ran through a 2000ft long test section on the runway, full braking used on a dry runway we would then flood the runway & repeat. I wasn't involved with the analasys work so I don't know what the outcome was
Green granite - Did you take part in some of these tests?
Early UK Research
ICAO Study Group on Snow, Slush, Ice and water on Aerodromes.
Memorandum No. 16
10 November 1970
Attachment B, Presented at Langley in November 1968 and published in the NASA report SP-5073.
Correlation between Runway Coefficient of Friction Values Produced by Different Types of Instruments and the Prediction of Aircraft Stopping Distances.
1. Introduction
The 5th Air Navigation Conference recommendation 5/32 states inter alia that ICAO invite interested States to co-operate in the further development of practical methods, suitable for international standardization, for calibrating coefficient of friction measurement devices and wet coefficient of friction of runway surfaces. In the UK research has been going on for a number of years to determine the possibility of predicting aircraft stopping distances using vehicular device and also to investigate the correlation between various devices. As the most hazardous conditions for a landing aircraft would occur when there was sufficient water or slush to cause aquaplaning or with surface ice, it was decided at the outset that a particular effort should be made to authenticate the prediction method in these situations. As trials with full scale aircraft under these extreme conditions with three different types of aircraft and three ground vehicles using different principles for measuring friction.
2. Trials between a Swift Aircraft and Road Research Laboratory Trailer
The first set of trials was conducted with a Swift fighter aircraft weighing approximately 18,000 lb and the Road Research Laboratory light friction trailer. The aircraft was instrumented to measure drag and vertical load as well as velocity from which the friction speed relationship curves were obtained at up to 140 knots for a number of runway surfaces, These curves were compared with those from the Road Research trailer at speeds up to 161 kph (100 mph= on the same surfaces. It was hoped that the ratio of friction coefficients at the same speeds might be a constant or at least that the change with speed might follow the same pattern from one type of surface to another. However, neither of these hopes was realised and it was concluded that there was no correlation between the actual friction values produced by an aircraft and the Road Research Laboratory Trailer.
3. Trials between a Hunter Aircraft and Heavy Load Friction Vehicle
The next series of trials in this study occurred some years later when the opportunity arose to compare the performance of a Hunter aircraft weighing about 17,000 lb and a Heavy Load Friction Vehicle which was fitted with a Hunter wheel, brake, tyre and braking system. The same tyre pressures, wheel loads, wetness conditions and surfaces were used. It was thought that under such closely comparable test conditions there should not only be correlation, but the actual figures themselves should be the same. This was however not the case and it led to the inevitable conclusion that correlation between friction values of aircraft and ground vehicles was most unlikely.
4. Trials between the Ministry of Technology Runway Friction Meter and a Convair 990 and F4 Aircraft
At the invitation of the NASA, the UK Ministry of technology conducted a joint Friction Correlation Programme at Wallops Station, Virginia, during 1968. Nasa had used a Convair 990 and F4 aircraft to determine the speed friction relationship of nine runway surfaces with widely differing friction coefficients. The programme was to compare these aircraft values with those from the Heavy Load Friction Vehicle, Road Research Trailer and a newly developed runway friction meter called the Mu-Meter. Once again the friction values did not correlate with the aircraft nor in fact with each other.