From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Report summarizing the results of cooperative knock ratings conducted by the Detonation Sub-committee in August 1931.
| Identifier | ExFiles\Box 27a\4\ Scan069 | |
| Date | 1st November 1931 | |
| NOVEMBER, 1931 A Gulf Publishing Company Publication 113 TABLE 1 Brief Summary of Results Obtained in the August, 1931, Series of Cooperative Knock Ratings Conducted by the Detonation Sub-committee Fuel | | B-1 | B-2 | B-4 | B-5 | B-6 | B-7 | B-8 ---|---|---|---|---|---|---|---|--- Measurements directly against heptane and octane | Mean octane number found.. | 77.8 | 49.1 | 73.0 | 67.0 | 55.5 | 64.2 | 77.8 | Average deviation from mean in octane numbers... | 1.25 | 0.75 | 0.7 | 0.35 | 1.4 | 0.65 | 0.55 | Maximum deviation from mean in octane numbers... | 2.4 | 1.1 | 1.4 | 1.0 | 2.5 | 1.2 | 1.0 | Mean deviation from true value, in percentage of reference fuel "B"... | 2.4 | 0.9 | 0.8 | 2.1 | 0.9 | 1.3 | ... Measurements matching blends of the same materials | Mean deviation from true value, in equivalent octane numbers | 1.0 | 0.3 | 0.4 | 0.3 | 0.2 | 0.2 | ... | Mean error,* in percentage of reference fuel "B"... | 3.5 | 1.8 | 1.2 | 2.9 | 1.5 | 1.8 | ... | Mean error,* in equivalent octane numbers......... | 1.5 | 0.6 | 0.5+ | 0.35 | 0.3 | 0.2 | ... *Mean error is the square root of the following quantity: the sum of the squares of the deviations divided by the number of observations included. ...were made by matching blends of the same materials, the mean deviation from the true values, expressed in equivalent octane numbers, varied from 1.0 octane number to 0.2 octane number. The average of all the mean deviations in this case was only 0.4 octane number. Presented also in Table 1 are summarized data on the mean error resulting when measurements were made by matching blends of the same materials. Mean error may be defined as the square root of the following quantity: the sum of the squares of the deviations divided by the number of observations included. As expressed in equivalent octane numbers, the mean error varied from 1.5 to 0.2, the average of all being 0.6. These results, which are a great deal better than those obtained in previous series of cooperative tests, show that the apparatus and procedure, as developed thus far, is capable of giving dependable results which are marked by a fair degree of accuracy, and, consequently, by reasonable agreement between different laboratories. APPROVAL BY THE COOPERATIVE FUEL RESEARCH COMMITTEE Upon the basis of the experience of the sub-committee with the knock-testing apparatus as developed thus far, and just described, the Cooperative Fuel Research Committee, at its regular meeting of September 14, 1931, approved the knock-testing equipment in its present form for general use by the two industries concerned. The octane number scale of anti-knock quality and the tentative procedure of test had previously been acted on favorably by the committee. The committee, at its meeting on September 14, also passed a resolution suggesting to Committee D-2 on Petroleum Products and Lubricants of the American Society for Testing Materials, that the combination of apparatus, procedure, and reference scale be considered as a possible tentative A.S.T.M. method for knock testing. DETONATION SUB-COMMITTEE CONTINUED The approval of this apparatus marked the completion of the work originally assigned to the sub-committee on methods of measuring detonation and thus automatically dissolved the group. However, the Cooperative Fuel Research Committee, feeling that the subject of knock testing is not by any means closed, voted to continue the sub-committee, and instructed it to work on "minor modification of the equipment and technique, relation of the test data to actual road performance of fuels in engines, and the possible use of the equipment in the evaluation of aircraft fuels." The sub-committee has already made plans for work on all three of these items, and work on the first two is under way. It is important to note that the apparatus and procedure as thus far developed is a laboratory method. As yet, the sub-committee has done no organized work on the correlation of laboratory results with behavior in automobile engines on the road; for, before laboratory results can be compared with road results in a comprehensive or cooperative manner, it is necessary to have a uniform laboratory procedure. However, it may be said that, in a general way, is known that two fuels of different compositions, but of equivalent anti-knock quality as measured in the laboratory, do not always behave alike in every automobile engine from the viewpoint of knock. Plans for investigating the possible usefulness of the apparatus for rating aircraft fuels are now being worked out with the cooperation of the Aeronautical Chamber of Commerce of America, and of representatives of the Army Air Corps, of the Bureau of Aeronautics of the Navy Department, and of the aircraft engine industry. COOPERATION ABROAD The cooperation of the sub-committee with people from other countries who are interested in knock | ||