Category AIRCRAFT STORIES

Before we go on with this story of what is absent—about the absence, for instance, of fear—we need to go back to the formalism to under­stand what is happening to G and to forget, for the moment, the crew:

‘‘If the gust response parameter, G, is fixed to give a certain response level, and the operational Mach number and the aircraft weight are also fixed, then from (1) it is clear that at-S becomes constant.’’ What is happening here? Let’s deal with formalism first.

If G (gust response), M (speed), and W (weight) are fixed, then the only terms that still have freedom to move are at and S. It’s easier to see what’s going on if we rewrite the first expression

M-at G = –

W/S

naissance operations in limited war using nuclear and conventional weapons. Such an aircraft will enable the Royal Air Force to continue to make an effective contribution to the strength of SACEUR’s shield forces, as well as to our other regional pacts.’’ SACEUR is an acro­nym for Supreme Allied Commander Europe, which tells us, as if we didn’t already know, that we have encountered another looming absence/presence: ‘‘We shall wish to consider whether there is a re­quirement for a low level weapon, either manned or unmanned, in case the Russian defences become effective against high flying air­craft and ballistic missiles’’ (AIR8/2167 1957). Here it is at last, made present not in OR 339 but in the correspondence of government min­isters.

And the defenses of the Russian enemy? A background document to OR 339, referring to the earlier Canberra, states that ‘‘the Canberras, operated strictly at a low level, may continue to be effective until the enemy develops an efficient low level surface to air guided weapon’’ (AIR8/2014 1956). A defensive, surface-to-air, guided weapon. If the attacking plane is to evade such a weapon, it must fly at high speed and low altitude.

Look now at exhibit 2.8, which reproduces the table of contents of the brochure. This makes more links, coordinates further versions of the TSR2. But how does it produce its coordinating effects?

Michel Foucault offers us the classic response. A table constitutes and juxtaposes components in a two-dimensional array. It generates 18 Objects new forms of visibility, new visual relations, which means that it cre-

ates a subject position that escapes the linearity and the syntax of text by virtue of its construction as an overall vantage point. This means, to use another metaphor, that a table draws things together. It draws them together by juxtaposing them spatially and by assuming, in that juxtaposition and ordering, that they are in some way linked. It thus performs the assumption that the different elements listed are simi-

lar in kind. And in the present instance, if one makes the link back to the framing of the brochure, that they concern the TSR2 in one way or another.

So the table implies and performs a form of coordination. When nouns and the different specific object positions appear in a list or a table, they are being made to go together. But this is simply a first step. For in the present instance at least, these relations of visual simulta­neity also perform relations of hierarchy. Components of the table, its elements, are being coordinated in ways that assure their asymmetry. Thus, it is not simply that what become the more important features of the object tend to come in the earlier pages of the brochure (though this is certainly one of the effects being achieved, both in the table of contents and in the overall structure of the publication). It is also that the elements in the table are ranked into three different levels. There are the three main sections, on “Performance,” “Operations,” and “Engineering”; a number of subsections, such as ‘‘Aircraft Perfor­mance,” ‘‘Radii of Action,’’ and ‘‘Ground Equipment’’; and then there are subsections to those subsections, which have to do with objects such as ‘‘fire protection’’ or ‘‘system test equipment.’’

So the table of contents, by virtue of its visible organization, not only homogenizes, not only proposes that everything in the table somehow or other goes together, but also makes a hierarchy in three levels. This means that the table of contents is like an organizational chart or an arborescence:5 the various elements are being defined, performed, and indeed guaranteed. Smaller parts are being ‘‘in­cluded” in the larger sections. They become specific ‘‘aspects” of larger unities—and, no doubt, of the TSR2 aircraft as a whole. Thus the reader is readily able to see that what has now become ‘‘the top” depends on, or is composed by, the links between a series of more specific components that have their role to play in the system ‘‘as a whole.”

In short, the table is a third strategy for coordinating disparate ob­jects and relating them together to form a unity. And the particular alchemy of the table is the way in which it returns, constantly, to that which is made central—ultimately, though here implicitly, the TSR2 — and performs what, echoing Jacques Derrida’s concern with necessary slippage (1978), one might think of as strategic deferral, for 20 Objects that which is left out is performed as ‘‘detail,’’ as ‘‘technical detail.’’

Note that the logic of strategic deferral—and the way in which it produces subject and object centering—extends beyond the covers of the brochure. For if this is only sixty pages long, then much must be excluded from its pages and deferred because it is ‘‘less impor­tant” or ‘‘relevant’’ than what is mentioned. Nevertheless (and here is the assumption of this strategy for coordinating, which is also a guarantee), it might be unpacked if the curious chose to look at “sup­plementary documentation” in some ‘‘technical manual’’ for reasons that are made to be good because, for a complex object such as an air­craft, it is important to perform links that are many layers down the hierarchical-technical system.

To summarize: the table, its structure, and its deferrals produce a hierarchy that generates a subject that has focus but also a coordi­nated object, one that hangs together because it has been constituted as a set of hierarchically related parts or aspects that combine to pro­duce a unitary whole.6

So we are dealing in multiplicity. Multiple forms for object positions.

Multiple styles of subject positions, interpellations. Donna Haraway (1994, 62) observes: ‘‘Optical metaphors are unavoidable in figuring technoscience.’’ And a few sentences later notes that ‘‘my favourite optical metaphor is diffraction—the noninnocent, complexly erotic practice of making a difference in the world, rather than displacing the same elsewhere’’ (Haraway 1994, 63).

Here I have made five forms of narrative, suggested five styles for making the interpellations of subject positions and object positions, five modes of distributing. These are the story forms that I have iden­tified: plain history, policy, ethics, the esoteric, and the aesthetic. I have, to be sure, made them unrealistically discrete. I wouldn’t pro­pose for one moment that they are fixed, unbridgeable, or primitive.

And even if one sticks with the labels, clearly they don’t represent in­variant and unchanging modes of interpellation. They are products of particular material-semiotic circumstances. But in the present con­text I have set the narratives up in this way, as discrete and separate, because I am interested in the ways in which they interfere with one another. In particular, this makes it easier to see that though they may individually make more or less coherent subject positions, something different starts to happen when several of them are juxtaposed. For when they start to interact with one another to generate complex pat­terns of interference, they also start to make subjects, readers, and au­thors that may be places of illumination when the wave patterns are coherent, but which may be places of darkness when they are not— when the wave patterns cancel one another out.

It is, of course, possible to make the argument in many ways. But here I want to link it to the formation of subjectivity. To the formation or the performance of what I hope we are no longer so disposed to think of as ‘‘the personal.”

So the story runs thus. In 1989 these patterns of narrative coalesced in a particular way to interfere with one another and make a place of darkness. They overlapped to produce a series of mutually destruc­tive interpellations, conflicting subject positions, a place where there was no possibility of writing, reading, or knowing.

I was writing history. This was the first interpellation. But it wasn’t ‘‘just history,’’ not in the way I imagined it. For plain history was never Subjects 59

the strongest form of interpellation for an author made as a sociolo­gist or a student of technoscience rather than a historian. So it was a prelude to what? I thought I was writing history as a prelude to a particular academic narrative, a story about human and nonhuman agents. So that was the second interpellation, the recognition or con­struction of a subject by an esoteric discourse: in this case the narra­tive of actor-network theory. But my high-status interviewees imag­ined that I was writing history, making my inquiries as a prelude to something quite different: a judgment of policy, a judgment about the worthiness of the project. So they thought I was going to write about whether or not it was well managed, what had gone wrong, why it had been canceled and, perhaps most important, whether or not it should have been canceled. This was a third interpellation and it was one that was powerful. It was an effect of what is sometimes called ‘‘studying up’’ and felt like a form of colonization.

So there were three simultaneous interpellations—but two of them were interfering with one another. The writer constituted as esoteric specialist and the writer as policymaker; in this context the two did not fit.29 So that was the first interference pattern. A place of dark­ness. But it was not the only one. There was also a resistance deriving from another story form, a long-ago story form, a story to do with the waste of military spending. This was a form of being that reflected and embodied a horror of nuclear weapons. Perhaps it was an ethical discourse that had been almost buried, long ago cleansed from other narrative forms, from those to do with either the esoteric or matters of policy. So what form did the interference take? I found I could not perform policy. I could not, that is, perform the kind of policy that judged the TSR2 in terms of its (how to say it?) efficacy with respect to military strategy or procurement policy. This was the point at which I stopped. I could not make that final move. Interpellation as a policy narrator interfered, though in different ways, with both esoteric and ethical subject positions.

Interpellation, diffraction, and interference, a moment of darkness, destructive—or at least immobilizing—subject multiplicity.30

Can we imagine this as “inauthenticity”? I don’t know, for certainly in a world of multiplicity there is no ‘‘core,’’ no last instance, no soul, no ultimately centered subject. Which means that authenticity, if that is what it is, rather has to do with the relations between narratives,

of the relations between different forms of obviousness, between the obviousnesses performed in different but related subject positions.

And what of the question of aesthetics? This was another form of interference, I think, for there is a pleasure in aircraft.

No. Let me be careful. Some of us, some of the time, some subject positions, are constituted to find various kinds of pleasure in rela­tion to machines, flying machines, and even killing machines. That is a whole other set of narratives, ways of talking and being that are pressed, or so I’d want to suggest, to the margins, in the narrative forms that I’ve mentioned above. My conclusion is that some version or other of machinic pleasure was what interpellated me one day, in RAF Cosford, in 1985, and then hid itself again. Which is some kind of answer as to why I ‘‘chose’’ to study TSR2 when I might have chosen to study so many other technologies.31

This chain of distributive differences is complex, but we don’t need to look into all of its ramifications. Retracing one line will do, one set of dis/connections.

Gust response, G, was fixed. It was fixed in a relation of materiality, material heterogeneity, the absence/presence of the sweating pilots. And Mach number, M, it turned out, was also fixed—because OR 339 said so. And why did OR 339 say so? In order to minimize the effect of enemy defenses. And the final set of dis/connections? The enemy turned out to be ‘‘the Russians’’ and the defenses ‘‘an efficient low level surface to air guided weapon.’’ Which means that ‘‘fear’’ and ‘‘the Russians’’ are not simply outside the formalism but also within it.

None of this is empirically extraordinary. In tracing this chain we’re not learning anything startling about the design of the P.17A. But we have learned something more about heterogeneity. We’ve learned that the enemy is within, that it is within the design, within the formal­ism. And the chain spells out one of the ways in which the enemy has been incorporated and assimilated.

This is another form of heterogeneity, another oscillation in differ­ences that are both absent and present. For the enemy and its surface – to-air guided weapons are a part of the formalism, a part of the wing design, rigorously present. At the same time, like the extended for­malism and the bodies of the pilots, they are just as rigorously absent. So this is a third form of heterogeneity, the heterogeneity of tellable Otherness. The enemy excluded, the foe that is necessary, necessarily included, necessarily a part of the center, necessarily Other.

“The Other”: this is a threat. The air force officers who write opera­tional requirements talk in just those terms. In their work they speak of “the threat.” “The Russians and their surface to air guided weapons” are like Edward Said’s Orientals (1991). They are necessary to the West, to its making of itself because they are dangerous, different, and antithetical. They play a similarly ambivalent role. For they are indeed a threat, a danger, something apart and something to be kept apart.

signed, or said.8 Fear is distributed as an absent presence in the center, in the formalism.

Earlier I suggested exhibit 2.1 is perspectival in character. But so too are exhibits 2.9 and 2.10. It is clear to all but the naive reader that these are pictures of the same object. In other words, we are justified in de­tecting the operation of yet another strategy for coordinating possibly different objects—that of perspectivalism.

I shall have more to say about this later, so let me just note for the moment that perspectivalism assumes a world that is Euclidean in character; that is, it assumes that the world is built as a three­dimensional volume occupied by objects. These objects, which in – Objects 21

elude a variety of positions for viewing, have locations and (at any rate in the case of objects) themselves occupy three-dimensional vol­umes.

This is why when we look at individual perspectival drawings of the kind in exhibits 2.9 and 2.10, we tend to see a three-dimensional object, for instance an aircraft, rather than some lines on a sheet of paper. The theory of linear perspective holds that we project the lines that appear on the paper in such a drawing back into a Euclidean vol­ume of space. That volume is occupied by a three-dimensional object that would, had it been located in such a space, have traced itself onto a two-dimensional surface in a way that corresponds with the lines on the sheet of paper. Thus in linear perspective a viewer or subject position is made that ‘‘sees’’ an ‘‘object,’’ the aircraft, even though it sees only a sheet of paper. Or, to put it differently, what is on the sheet of paper tends to produce the sense of an object because it helps to reproduce a Euclidean version of reality.

Furthermore, and an important part of this strategy, different per- spectival sketches are easily coordinated within the system. There is a formal projective geometry for saying this, but let me put it infor­mally. One of the Euclidean assumptions of perspectivalism is that a single three-dimensional object can generate multiple two-dimen­
sional perspectival depictions. Objects, the same objects, simply look different if we look at them from different standpoints. And this is what is happening here. The coordinating assumption is that there is an aircraft, the TSR2, and that it is fixed in shape. That singular fixity will generate all sorts of possible two-dimensional perspectival configurations. So long as the depictions conform to these configu­rations and do not demand an impossible three-dimensional object, then we tend to see the same three-dimensional object when we look at different perspectival drawings, as we do here.

I started this chapter with two beginnings. One had to do with multi­plicity, indirection, and the coherence of subject positions. The other concerned the reflexive problem of the personal. Now it is possible to say that they overlap and interfere with one another.

Some observations.

I want to assert, against the purifying tropes of modernism, that whatever is personal is also social. Always. Whatever we conceal, we think is shameful, inappropriate, self-indulgent, uninteresting, what­ever we conceal is also social. Elias tells us this.

It may, of course, also be shameful, inappropriate, self-indulgent, or plain, downright uninteresting at the same time as being as social.

All of these are real possibilities which we watch being performed every day. They are, indeed, performed in one way by Elias and Fou­cault in their writing—if only because they choose never to talk about their own “repressions,” their own subjectivities. But if we assume, as I have in this chapter, that narratives perform subject positions and object positions, then there is, at least in principle, the possibility that subject positions, those positions that constitute us as knowing sub­jects, are relevant if we want to understand the performativity of nar­ratives, to understand how distributions are being made, if we want to understand what is being said and what is not.

So that is a first possibility. There is continuity between subjects Subjects 61

and objects, and we are lodged in, made by multiple and overlap­ping distributions, which shuffle that which is made ‘‘personal’’ and that which is rendered ‘‘eternal’’ into two heaps. And that process of shuffling is worthy of deconstructing in a contemporary version of the vanitas because it performs obviousnesses. And in particular be­cause it performs obviousnesses.

This is where, having journeyed almost all the way with the semi­otics of Michel Foucault and Louis Althusser, I finally part company from them. This is a methodological point. For I would argue that the body is a particularly sensitive instrument in part precisely because the semiotics of subject-object relations don’t come in big blocks like ideologies, discourses, or epistemes. Let me be more cautious. They may come in big blocks in certain respects. Perhaps the conditions of possibility are, indeed, in some ways uniform, singular. But they aren’t that way all the time. For smaller blocks, narratives, semiotic logics, distributions—these are multiples that are also capable of in­terfering with and eroding one another. At any rate they are capable of doing so under certain circumstances, in particular places or insti­tutions. They can produce multiplicities that do not effortlessly coa­lesce to make singularities. In, for instance, the practices within a building, the intertextualities that pass through the body, the hetero­topic space within that makes us, interpellates us and our materials in multiple ways.32

Lighten our darkness. Deliver us this day from the obviousness of our simplicities.

This is why I am more optimistic than Louis Althusser. There is mileage to be gained by attending to interferences that make multi­plicities. And it is also why the body is so important. For it is a de­tector, a finely tuned detector of narrative diffraction patterns. It is an exquisite and finely honed instrument that both performs and detects patterns of interference, those places where the peaks come together and there is extra light. And those, such as the place I found myself in the summer of 1989, where there is dark, where there is some­thing wrong, where the energies cancel one another out. Where multi­plicity is not reduced.

This suggests that there is a place for the body, not only as the flesh and narrative blood that walks in what we used to call ‘‘the field’’ 62 Subjects bringing back reports, reports of how it is ‘‘out there,’’ but also that

there is room for the body, for the personal, in the narratives that are later performed, that perform themselves through us as we tell of nar­rative diffractions and interferences. For the personal, when we come to sense it in this way, is no longer ‘‘personal.’’ It is no longer nec­essarily personal, however it may be constructed by the modernist – inclined heirs to the civilizing process. It may be understood and performed rather as a location, one particular location, of narrative overlap. A place of multiplicity, of patterns, of patterns of narrative interference. And of irreduction.

Whether we tell stories about ourselves as we perform our situated knowledges will depend on what we are trying to achieve and on the context in which we are seeking to achieve it. The performance of re – flexivity and diffraction does not necessarily demand the immediate visibility of a narrator. But the issues are situated, specific, rhetorical, and political in character rather than great issues of principle. For it is itself wrong, a confusion, a self-indulgence, to forget that the body is a site, an important site, where subjectivities and interpellations produce effects that are strange and beautiful—indeed sometimes ter­rible. And these are effects that might make a difference if were able to attend to their intertextualities.

For instance, there are moments—I lived through one that I have already described—when the possibility of performing coordination between narratives is lost and it is no longer possible to link subject positions together in this way or that, to make a single story; when it is no longer possible to create, perform, and be performed by an ob­ject that is turned into a singularity; when it is no longer possible to work, as it were, perspectivally. In such moments, the interferences and overlaps perform themselves into ‘‘a’’ subject that is broken, frag­mented, and decentered; a subject that is therefore interpellated by— and interpellates—a multiplicity of different objects and thereby sud­denly apprehends that the failure to center is not simply a failure but also a way of becoming sensitive to the multiplicities of the world. At that moment, failure to center is also a way of learning that objects are made, and that there are many of them. It is a way of learning that objects are decentered—aset of different object positions—and a way of attending to the indirections of interference. It is also a way of ap­prehending that knowing is as much about making, about ontology, about what there is, as it ever was about epistemology. Subjects 63

A final question. Could I have done all this without introducing the personal?

The answer is no. Perhaps I could have made arguments like these and told it otherwise in some version or other of the god-trick. But this is not how the method of bodily interference produced its effects. So I’ll finish with another question. If we are constituted as know­ing subjects, interpellated, in ways that we do not tell, then what are we doing? What are we telling? What are we making of our objects of study? Or, perhaps better, what are they making of us?

The question is real, isn’t it? At any rate it’s real from where I stand. For finally, in a study of the TSR2, it turns itself into something spe­cific that is also not specific. If those of us who study military tech – nologies—and those who dream of them, design them, fly them—do not reflect on the aesthetics of our interpellations then we are not at­tending to a way of living stories that runs through us. A way of living stories that is arousing, in some ways dangerously so, that effaces the ontological in favor of the perspectival, and that makes a difference and continues to strain toward the singularities of military and tech­nological discourse.33 This is the power of a reflexive technoscience studies: it can attend to, and learn from, dangerous arousal.

Multilingualism is not merely the property of several systems each of which would be homogeneous in itself: it is primarily the line of flight or of varia­tion which affects each system by stopping it from being homogeneous. —Gilles Deleuze and Claire Parnet, Dialogues

So there are multiplicities. There are multiple distributions of sub­jects and multiple distributions of objects. And these distributions overlap. Sometimes the overlaps work to make patterns of light, somewhat singular narratives. Sometimes they consolidate them­selves to make coherences, simplicities. And sometimes they do not —and then we find that we are left in the dark places, turned into a fragmented set of subject positions confronted by an equally unco­ordinated set of object positions.

No doubt this is uncomfortable. But, if we can work it right, per­haps in those dark moments it is easiest to learn about the making of objects and the making of subjects because in those moments it is easiest to attend to the work of distribution and coordination. And, in particular, those are the moments when it is easiest to avoid being dazzled by problems of epistemological authority and deal, instead, with ontology: with the making of what there is or there could be, with the conditions of possibility. With the performances that other­wise tend to reenact singularity. This, then, is the interest in interfer­ences, that they allow us both to rethink and survey the character of distribution—with how it is that matters are made and arranged in the world.

In this chapter I follow Sharon Traweek and tell more stories while looking for the distributions that they make. I also follow Annemarie Mol by attending to the ways stories describe and make links: con­nections and disconnections or similarities and differences—that is, by attending to their interferences.11 argue that to tell stories is to per­form ‘‘cultural tasks.’’ It is to distribute, to say what exists or does not. And it is to coordinate, to saywhat goes with or does not go with, what else. This means that I’m assuming, as I have above, that storytelling is performative: it makes or may make a difference in the multilingual world mentioned by Gilles Deleuze and Claire Parnet. Talk may, as it were, talk itself into being, and the stories told may shift their ma-

terial form, may perform their logic from texts or voiced words into bodies and architectures, into other forms of flesh, and into stone. So the echoes here are also with that material version of semiotics called actor-network theory and with the understandings in cultural anthropology or cultural studies of the ways in which, for instance, communities may be imagined and told into being as different stories overlap.2

Let’s go back to the fixing of parameters. Remember: ‘‘If the gust re­sponse parameter, G, is fixed to give a certain response level, and the operational Mach number and the aircraft weight are also fixed, then from (1) it is clear that at-S becomes constant.’’ So G and Mare fixed.

Now let’s turn to W So why or how has weight been fixed? This is another paper chase. It takes us to a document that we have come across before:

It is desirable both from the point of view of development time and cost, that a proposed aircraft to any given specification should be as small as possible. For any project study the opti­mum size of aircraft is obtained by iteration during the initial

design stages. The size of aircraft which emerges from this itera­tion process is a function of many variables. Wing area is deter­mined by performance and aerodynamic requirements. Fuselage size is a function of engine size and the type of installation, vol­ume of equipment, fuel and payload, aerodynamic stability re­quirements and the assumed percentages of the internal volume ofthe aircraft which can be utilised. (English Electric/Short Bros. 1958, 2.1.8)

So there are many variables, too many for us to magnify. Let’s stick with engines. For aircraft size (and therefore weight) is not simply a matter of the ‘‘size and type of installation.” It’s also, and even more immediately, a function of the number of engines. Here is OR 339 again: ‘‘The Air Staff require the aircraft design to incorporate two en­gines’’ (Air Ministry 1958, para. 9). Two engines. But why? Well, we already know the answer because we looked at the English Electric brochure in the previous chapter. Pilots don’t like flying supersonic aircraft with only one engine when that engine fails.9 So the pilots are back again. This time they are not being frightened by oscillation or nauseated, but they are worrying about something else. Another dif­ference that is absent but present: the worry is that supersonic aircraft are more likely to crash, and the OR 339 aircraft has to travel a long way from home.

But there are other possible differences. We know that Vickers Arm­strong wanted a single-engine aircraft: ‘‘From the very beginning of our study of the G. O.R. we believed that if this project was to move forward into the realm of reality—or perhaps more aptly the realm of practical politics—it was essential that the cost of the whole project should be kept down to a minimum whilst fully meeting the require­ment. This led us towards the small aircraft which, by concentrating the development effort on the equipment, offers the most economical solution as well as showing advantages from a purely technical stand­point.’’10 And these were the arguments: it would sell better; it would be more lethal per pound spent; and it could interest the Royal Navy because they might use it on their aircraft carriers (Vickers Armstrong 1958c, 2-3).

Present/ Absent
FIGURE 5.6
Weight

Heterogeneity/Noncoherence

Aircraft safety, pilot worry, the need to fly far from base. This set of considerations tends to fix W at a higher value and thus make the air­craft heavier. Cost, cost-effective lethality, naval use, practical poli­tics, sales, this second set of considerations tends to fix W at a lower value and thus make the aircraft lighter.

So there are two sets of connections, two sets of relations of differ­ence. This is old territory for those who study technoscience. It’s a controversy. As we know, the Air Ministry is going to disagree with Vickers and stick with its large, twin-engine aircraft: ‘‘The reply by D. F.S. to D. O.R.(A)’s request for a study on the single versus twin en­gined aircraft was received 16th July. It showed fairly conclusively that the twin engined configuration is the less costly in accidents’’ (AIR8/2196 1958b, para. 43).

But if it is a controversy, it is something else too. It is another form of absence/presence. For controversy and disagreement are absent from W. They are absent from the formalism. There is no room for con­troversy in formalisms. Trade-offs, reciprocal relations, all kinds of subtle differences and distributions yes, but controversies no. And noncoherences not at all.

For, if the arguments about the size of the aircraft, about W, about the number of engines it should carry, are a form of controversy, they are also an expression of noncoherence, dispersal, and lack of con­nection. For the Air Ministry is talking about one thing while Vickers

Another convenient parameter is one which gives an indica­tion of the relative response to gusts while achieving a given take­off distance. This may be expressed as P say, where

P =

lf

where CLf is the maximum trimmed CL, flaps down, in touch­down attitude. P must be a minimum for good design. (English Electric/Short Bros. 1958, 2.1.9)

We’ve met these terms before. A reminder:

— CL is lift coefficient, roughly the lifting force of a wing: here, the lifting force of the wing as the plane comes into land with its flaps down.

—And at is lift curve slope, change in lift against change in angle of attack.

P therefore quantifies a hybrid relationship, the hope that it is pos­sible to find a wing with low transonic gust response and high lift at landing.

But how to find a wing of the right shape? Of the right planform. This is a technical term and it is one of some importance. The bro­chure continues: ‘‘In the absence of comprehensive data on the effects of flaps on low aspect ratio wings, a comparison replacing CLf by CLmax indicated that delta wings were superior to trapezoidal and swept wings’’ (English Electric/Short Bros. 1958, 2.1.9). The terms here?

— CLmax is the aerodynamicist’s way of designating maximum lift. —Low aspect ratio wings (a reminder) are wings that are short in relation to their area.

—Delta wings are triangular, like those of a paper dart.

—And a trapezoidal wing is shaped like a trapezium. That is, though the wing tip is parallel to the root of the wing, the leading and trailing edges converge toward that tip.

The paragraph then discusses planform:

Since it was thought possible that by using leading edge flaps on trapezoidal wings, higher values of CLf might be obtained

than those from delta wings, wind tunnel tests were carried out using a trapezoidal wing-body combination. In the event, these tests confirmed that the delta gave higher values of CLf. The delta planform was also expected to have better transonic char­acteristics, and again high speed tests in our 18" tunnel on a family of aspect ratio = 2 planforms confirmed the unsatisfactory characteristics of trapezoidal wings, with sudden large aerody­namic centre movements at transonic speeds. This confirmed the choice of the delta planform. (English Electric/Short Bros. 1958, 2.1.9)

A further explanation. This time about aerodynamic center. As it moves through the air a wing lifts, but it does so by differing amounts in different parts of the wing. It’s useful to simplify, however, and sum the effect of all these separate parts to create something called the aerodynamic center. Roughly, this is the place in the wing where the

FIGURE 5.7 Trapezoidal Wings

changes in overall lift occur as it flies faster or slower or its angle of attack changes. Above stalling speed the aerodynamic center doesn’t shift much. At subsonic speeds it’s about one quarter back from the leading edge for most wings. But at around the speed of sound the aerodynamic center tends to move backward. This isn’t a disaster un­less it moves quickly and jerkily, in which case the aircraft can be difficult to control—which would take us back to pilot sweat and fear.

So the English Electric engineers were looking at two things. One was aerodynamic center. Here the trapezoidal wing was a problem because the movement was ‘‘sudden’’ and ‘‘large.’’ The delta wing was better. The second was CLmax (max, here, means maximum lift). Here

there was a surprise: the delta wing was better again. On both counts the trapezoidal wing came off worse.