Tech­ni­cal fo­cus: Mclaren MP4/4

This ex­tract from Haynes’ lat­est in­sight into the work­ings of one of mo­tor­sport’s most fa­mous de­signs ex­am­ines what made 1988’s MP4/4 so spe­cial

Autosport (UK) - - CONTENTS -

IN­TRO­DUC­TION

When the MP4/4 ap­peared for the very first time at the now fa­mous pre-sea­son Imola test, it was im­me­di­ately ob­vi­ous that the car was sig­nif­i­cantly faster than both its ri­vals and the MP4/3B en­gine-test mule.

The only ap­par­ent ques­tion mark at the be­gin­ning of the sea­son was over re­li­a­bil­ity – purely due to the lack of pre-sea­son test­ing miles.

Al­though there were a few teething prob­lems – no­tably with the gearchange mech­a­nism and the manda­tory Fia-sup­plied pop-off valves – the car proved re­mark­ably re­li­able from the out­set. Be­cause the car was fun­da­men­tally quick, Mclaren was able to main­tain its edge through­out the sea­son, so neg­li­gi­ble time was spent on development. The ma­jor­ity of the ex­ten­sive 1988 test pro­gramme con­cen­trated on development and re­li­a­bil­ity of the Honda en­gine, which proved re­mark­ably ro­bust. Honda’s en­gine-test­ing pro­gramme in Ja­pan was re­lent­less, with test driver Emanuele Pirro com­plet­ing around 10,000 miles over the year. Later in the sea­son the team felt able to con­cen­trate its development ef­forts on the forth­com­ing nor­mally as­pi­rated car for 1989 – the MP4/5.

With the ex­cep­tion of en­gine re­vi­sions and mod­i­fi­ca­tions to the turbo-in­ter­cooler lay­out and air in­takes, the car re­mained fun­da­men­tally un­changed through­out the sea­son. The team saw no rea­son to ex­pend re­sources and pos­si­bly com­pro­mise re­li­a­bil­ity in or­der to make sig­nif­i­cant de­vel­op­ments to a car that was al­ready the class of the field, as Steve Ni­chols ex­plains: “We didn’t do a lot of development dur­ing the sea­son be­cause the car was very, very good. We were faster than every­body by a long way, and we were con­cen­trat­ing our ef­forts on the MP4/5, be­cause that was the car of the fu­ture. The MP4/4 car was a dead end – we were only go­ing to use it for one year.”

CHAS­SIS

The mono­coque ge­ome­tries for the Mclaren MP4/4’S pre­de­ces­sors – the MP4/2 and MP4/3 – were de­scended from John Barnard’s orig­i­nal pi­o­neer­ing MP4/1, which fea­tured the first all-car­bon­fi­bre (also known as ‘car­bon­fi­bre re­in­forced plas­tic’ – CFRP) mono­coque to ap­pear in For­mula 1. Ni­chols was in­stru­men­tal in the in­volve­ment of Her­cules Aero­space with the con­struc­tion of the MP4/1 mono­coque, and Her­cules would con­tinue to be in­volved as the ma­te­rial sup­plier for the MP4/4 tub, as he ex­plains: “For the early [MP4/1] mono­coque, Her­cules made the ba­sic com­po­nents in Salt Lake City – the mono­coque shell, the bulk­heads and so on. They made them and au­to­claved them, and we would re­ceive those ba­sic com­po­nents and bond them all to­gether to com­plete the mono­coque. At a very early stage we had our own au­to­clave. In fact, when we moved sites [from the orig­i­nal Bound­ary Road site to Wok­ing Busi­ness Park], they had to tear down the wall of the build­ing to get the au­to­clave out! By the time of the MP4/4, Her­cules were just sup­ply­ing us with the car­bon pre-preg ma­te­ri­als [rather than be­ing in­volved di­rectly in the man­u­fac­ture].”

Al­though many of the con­struc­tion meth­ods em­ployed for pre­vi­ous Mclaren tubs would be car­ried over for the MP4/4, the mono­coque it­self was an all-new de­sign to take ad­van­tage of the op­por­tu­ni­ties pro­vided by the re­duced fuel-tank ca­pac­ity and the lower en­gine and gear­box, plus the re­quire­ment for the driver’s feet to be po­si­tioned be­hind the front-axle cen­tre­line. The fun­da­men­tal dif­fer­ence be­tween the MP4/4 mono­coque ge­om­e­try and its pre­de­ces­sors was that the MP4/4 tub fea­tured a flat floor and ver­ti­cal sides, rather than the ‘V’ pro­file em­ployed on pre­vi­ous chas­sis.

By 1988 most F1 teams man­u­fac­tured their car­bon mono­co­ques us­ing a fe­male mould, whereas Mclaren con­tin­ued to use male tool­ing (as they had from the out­set with the MP4/1). There were three main rea­sons be­hind this de­ci­sion:

• It was pos­si­ble to make a single-piece mono­coque shell – ad­van­ta­geous for over­all strength and stiff­ness.

• By hav­ing largely flat pan­els, it was pos­si­ble to use a higher per­cent­age of uni­di­rec­tional (UD) fi­bres in the mono­coque struc­ture, which is ben­e­fi­cial in terms of strength- and stiff­ness-to-weight com­pared to wo­ven CFRP (wo­ven CFRP would have to be used for a fe­male-moulded mono­coque if the outer mono­coque sur­faces were aero­dy­namic sur­faces, ie ex­posed di­rectly to the air­flow and not clothed with body­work, as was the case with some ri­val cars, such as the Williams).

• Us­ing a flat-pan­elled mono­coque with sep­a­rate body­work meant there was some scope to change the outer aero­dy­namic sur­faces if nec­es­sary, for the MP4/4 or de­vel­op­ments of the car in the fu­ture.

MP4/4 was so quick and re­li­able that it needed neg­li­gi­ble development

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