SAWE Technical Papers

abstract = {Automotive longitudinal acceleration is dependent upon a large number of interconnected parameters, some of the most important of which are mass properties. The purpose of this paper is to explore the individual mass property effects.

The approach taken to achieve this purpose was to decouple the parameters by means of a computer simulation of an automotive acceleration 'run'. Each individual mass property parameter was then varied over a wide range while all other parameters were held constant. The acceleration results so obtained were plotted, and the conclusions were drawn from the behavior thus exhibited.

Several conclusions have been drawn from this effort. First, the effects of a mass property parameter variation are not necessarily constant over the entire speed range. For instance, increasing weight tends to cause an almost linear increase in the elapsed times for the lower speed ranges, but the higher speed ranges exhibit even greater time increases in an almost parabolic relationship. This is a matter of the increased rolling resistance associated with greater weight making itself felt at the higher speeds.

The longitudinal center of gravity (kg) and the vertical center of gravity (vcg) both affect acceleration through traction. If the situation is not traction critical then cg relocation can be of no help in obtaining better acceleration. When a situation is traction critical then acceleration is much more sensitive to change in kg then in vcg.

Increasing the vertical center of gravity tends to benefit the acceleration of rear wheel drive vehicles. For rear wheel drive vehicles the vcg generates increased traction through weight transfer. In the case of front wheel drive, the vcg can have no beneficial effect as the weight transfer is in the direction away from the drive axle; minimizing the vcg becomes the priority. Due to the effect of weight transfer, a front wheel drive vehicle will always be inferior in acceleration to a rear wheel drive vehicle if everything else is equal and the propulsive capability is great enough.

In general, a rotational mass is disproportionately detrimental to acceleration because it has to be accelerated both rotationally and translationally. The greatest return for the effort involved in mass reduction can be obtained from a reduction in rotational masses.

The engine rotational masses, other than the flywheel, represent a special case outside the scope of this paper. Vehicle characteristics and use demand a certain minimal rotational inertia for the flywheel to counteract engine stall-out tendencies at the onset of acceleration and to ensure smooth engine operation. In fact, a higher flywheel inertia can produce an initially quicker vehicle. This initial response has to be considered against the detrimental longer-term effects of accelerating a large flywheel inertia throughout the speed range. Flywheel design involves a high degree of compromise.

Rev A - 2023},

keywords = {31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

Close

Automotive longitudinal acceleration is dependent upon a large number of interconnected parameters, some of the most important of which are mass properties. The purpose of this paper is to explore the individual mass property effects.
The approach taken to achieve this purpose was to decouple the parameters by means of a computer simulation of an automotive acceleration 'run'. Each individual mass property parameter was then varied over a wide range while all other parameters were held constant. The acceleration results so obtained were plotted, and the conclusions were drawn from the behavior thus exhibited.
Several conclusions have been drawn from this effort. First, the effects of a mass property parameter variation are not necessarily constant over the entire speed range. For instance, increasing weight tends to cause an almost linear increase in the elapsed times for the lower speed ranges, but the higher speed ranges exhibit even greater time increases in an almost parabolic relationship. This is a matter of the increased rolling resistance associated with greater weight making itself felt at the higher speeds.
The longitudinal center of gravity (kg) and the vertical center of gravity (vcg) both affect acceleration through traction. If the situation is not traction critical then cg relocation can be of no help in obtaining better acceleration. When a situation is traction critical then acceleration is much more sensitive to change in kg then in vcg.
Increasing the vertical center of gravity tends to benefit the acceleration of rear wheel drive vehicles. For rear wheel drive vehicles the vcg generates increased traction through weight transfer. In the case of front wheel drive, the vcg can have no beneficial effect as the weight transfer is in the direction away from the drive axle; minimizing the vcg becomes the priority. Due to the effect of weight transfer, a front wheel drive vehicle will always be inferior in acceleration to a rear wheel drive vehicle if everything else is equal and the propulsive capability is great enough.
In general, a rotational mass is disproportionately detrimental to acceleration because it has to be accelerated both rotationally and translationally. The greatest return for the effort involved in mass reduction can be obtained from a reduction in rotational masses.
The engine rotational masses, other than the flywheel, represent a special case outside the scope of this paper. Vehicle characteristics and use demand a certain minimal rotational inertia for the flywheel to counteract engine stall-out tendencies at the onset of acceleration and to ensure smooth engine operation. In fact, a higher flywheel inertia can produce an initially quicker vehicle. This initial response has to be considered against the detrimental longer-term effects of accelerating a large flywheel inertia throughout the speed range. Flywheel design involves a high degree of compromise.
Rev A - 2023

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1400. The Significance of Weight on Light Trucks

Moulton, G R

In: 40th Annual Conference, Dayton, Ohio, May 4-7, pp. 7, Society of Allied Weight Engineers, Inc., Dayton, Ohio, 1981.

Abstract | Buy/Download | BibTeX | Tags: 31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement

1369. The Effect of Government Regulations on Vehicle Weight

Allmacher, M H

In: 39th Annual Conference, St. Louis, Missouri, May 12-14, pp. 23, Society of Allied Weight Engineers, Inc., St. Louis, Missouri, 1980.

Abstract | Buy/Download | BibTeX | Tags: 31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement

@inproceedings{1369,

title = {1369. The Effect of Government Regulations on Vehicle Weight},

author = {M H Allmacher},

url = {https://www.sawe.org/product/paper-1369},

year = {1980},

date = {1980-05-01},

booktitle = {39th Annual Conference, St. Louis, Missouri, May 12-14},

pages = {23},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {St. Louis, Missouri},

abstract = {The domestic automakers are currently going through a revolutionary change, not just an evolutionary change, whereas the corporations are changing in their outlook on vehicle size, performance, fuel economy, and organization. General Motors has already spent over $1 billion on the 'X' body vehicles and is planning to spend billions more in the development of smaller, more fuel-efficient vehicles. Ford has spent $700 million to develop a new, smaller pickup truck for 1980, and has a front wheel drive passenger car slated for the market in 1981. Chrysler Corporation has the 'K' car developed and ready for the market. This is dependent on whether or not they can survive long enough to recover from their current economy problems. American Motors, already streamlined and downsized, along with their partnership with Renault, has a very bright future in the auto industry. However, they too have to survive through the next few months or until this recession abates. Volkswagen, the newest entry of domestic automakers, also has a very bright future in the U.S. with one plant assembling cars and trucks to capacity and a second plant scheduled to open in the very near future. The next few months will also be critical to them with respect to economic conditions.

The primary reason for the domestic automakers' revolutionary changes is due to the need for vast amounts of fuel-efficient vehicles in a very short period of time. It appears that the American public has changed their thinking on vehicle size faster than the auto industry can supply their needs. With the price of fuel continually going up, the domestic buyer has set aside his fondness for the large car and opted for the more fuel-efficient, smaller vehicle. He has, however, not given up his desire to own a personalized vehicle that is loaded with convenience options. For this reason, and because the Federal Government has mandated corporate average fuel economy standards, the automobile industry must downsize their vehicles to meet the demand of today's market. GM, just recently, has laid-off 18,000 white collar workers or 10% of their white collar work force, just to keep money available for their future programs, which they say will not be sacrificed because of the present economic conditions, if at all possible. The NHTSA, in regulating motor vehicles, has affected virtually every portion of the automobile. The following pages reveal some of the standards that affect vehicle weight and what portions of the vehicles were affected by these standards. It shows, although weight was affected, this weight increase was necessary to bring vehicles within the compliance of the law. Since the enactment of the Corporate Average Fuel Economy law (CAFE), which is also the responsibility of the NHTSA, regulating of motor vehicles will be scrutinized much closer than in the past for weight impact. This dual responsibility would lead you to believe that the NHTSA inner departments will be working closer together during their rulemaking activities. Also, because of the fuel economy requirements, and the new regulations that are coming, internal departments within the domestic automakers will naturally be working closer together. If closer, informal communications and cooperation could now be established between the NHTSA and the industry, it would be reasonable to expect future new models to be safer while at the same time more fuel efficient.},

keywords = {31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

Close

The domestic automakers are currently going through a revolutionary change, not just an evolutionary change, whereas the corporations are changing in their outlook on vehicle size, performance, fuel economy, and organization. General Motors has already spent over $1 billion on the 'X' body vehicles and is planning to spend billions more in the development of smaller, more fuel-efficient vehicles. Ford has spent $700 million to develop a new, smaller pickup truck for 1980, and has a front wheel drive passenger car slated for the market in 1981. Chrysler Corporation has the 'K' car developed and ready for the market. This is dependent on whether or not they can survive long enough to recover from their current economy problems. American Motors, already streamlined and downsized, along with their partnership with Renault, has a very bright future in the auto industry. However, they too have to survive through the next few months or until this recession abates. Volkswagen, the newest entry of domestic automakers, also has a very bright future in the U.S. with one plant assembling cars and trucks to capacity and a second plant scheduled to open in the very near future. The next few months will also be critical to them with respect to economic conditions.
The primary reason for the domestic automakers' revolutionary changes is due to the need for vast amounts of fuel-efficient vehicles in a very short period of time. It appears that the American public has changed their thinking on vehicle size faster than the auto industry can supply their needs. With the price of fuel continually going up, the domestic buyer has set aside his fondness for the large car and opted for the more fuel-efficient, smaller vehicle. He has, however, not given up his desire to own a personalized vehicle that is loaded with convenience options. For this reason, and because the Federal Government has mandated corporate average fuel economy standards, the automobile industry must downsize their vehicles to meet the demand of today's market. GM, just recently, has laid-off 18,000 white collar workers or 10% of their white collar work force, just to keep money available for their future programs, which they say will not be sacrificed because of the present economic conditions, if at all possible. The NHTSA, in regulating motor vehicles, has affected virtually every portion of the automobile. The following pages reveal some of the standards that affect vehicle weight and what portions of the vehicles were affected by these standards. It shows, although weight was affected, this weight increase was necessary to bring vehicles within the compliance of the law. Since the enactment of the Corporate Average Fuel Economy law (CAFE), which is also the responsibility of the NHTSA, regulating of motor vehicles will be scrutinized much closer than in the past for weight impact. This dual responsibility would lead you to believe that the NHTSA inner departments will be working closer together during their rulemaking activities. Also, because of the fuel economy requirements, and the new regulations that are coming, internal departments within the domestic automakers will naturally be working closer together. If closer, informal communications and cooperation could now be established between the NHTSA and the industry, it would be reasonable to expect future new models to be safer while at the same time more fuel efficient.

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1392. A Method of Analyzing Actual Automotive Weights

Webster, J

In: 39th Annual Conference, St. Louis, Missouri, May 12-14, pp. 18, Society of Allied Weight Engineers, Inc., St. Louis, Missouri, 1980.

Abstract | Buy/Download | BibTeX | Tags: 31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement

1322. Automotive Mass Control From Concept Through Production

Harris, R L

In: 38th Annual Conference, New York, New York, May 7-9, pp. 12, Society of Allied Weight Engineers, Inc., New York, New York, 1979.

Abstract | Buy/Download | BibTeX | Tags: 31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement

1323. A Semiempirical Method for Predicting Urban Railcar Structural Weight

Hooker, D M

In: 38th Annual Conference, New York, New York, May 7-9, pp. 7, Society of Allied Weight Engineers, Inc., New York, New York, 1979.

Abstract | Buy/Download | BibTeX | Tags: 31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement

1247. Designing an Electromagnetic Levitation System for High Speed Ground Transportation Vehicles

Nave, P M W

In: 37th Annual Conference, Munich, West Germany, May 8-10, pp. 7, Society of Allied Weight Engineers, Inc., Munich, West Germany, 1978.

Abstract | Buy/Download | BibTeX | Tags: 31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement

1255. Road Stress Resistance and Lightweight Construction of Automobile Road Wheels

Wimmer, A Dr.

In: 37th Annual Conference, Munich, West Germany, May 8-10, pp. 20, Society of Allied Weight Engineers, Inc., Munich, West Germany, 1978.

Abstract | Buy/Download | BibTeX | Tags: 31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement

1256. Compatibility in Car-To-Car Frontal Collisions

Wagner, R

In: 37th Annual Conference, Munich, West Germany, May 8-10, pp. 11, Society of Allied Weight Engineers, Inc., Munich, West Germany, 1978.

Abstract | Buy/Download | BibTeX | Tags: 31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement

1257. Todays Challenge in Rail Transit

Hooker, D M; Cord, J M

In: 37th Annual Conference, Munich, West Germany, May 8-10, pp. 9, Society of Allied Weight Engineers, Inc., Munich, West Germany, 1978.

Abstract | Buy/Download | BibTeX | Tags: 31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement

1059. Weight and Performance Characteristics of Magnetically Suspended High-Speed Trains as Compared to Aircraft

Herbst, W

In: 34th Annual Conference, Seattle, Washington, May 5-7, pp. 22, Society of Allied Weight Engineers, Inc., Seattle, Washington, 1975.

Abstract | Buy/Download | BibTeX | Tags: 31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement

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