# Bruce Carmichael's "drag reduction" book

### Help Support Homebuilt Aircraft & Kit Plane Forum:

#### gschuld

##### Well-Known Member
Other than a single positive mention by Billski in an older post, I have not been able to locate any significant mentions about these two publications by Bruce Carmichael on this site. I am feeling the need to expand my aircraft related library some more, and the subject matter is of particular interest to me. Any opinions?

BRUCE CARMICHAEL'S PERSONAL AIRCRAFT DRAG REDUCTION

Bruce Carmichael's
Personal Aircraft Drag Reduction
3rd Printing 2000. U.S. Softcover 8 x11. 215 Pages, 195 Illustrations, 239 References. 1800 copies sold to date. Research and Development History 1883 to Present, Laminar Aircraft Development History, 16 Outstanding Aircraft Analyzed, Drag and Performance Estimation Methods, Drag Minimization and Data with Extensive Laminar Flow on Wings, Fuselages, Tails, and Landing Gear, Interference Drag, Cooling Drag, Practical Problems and Solutions, Flight Test Methods, Cruise Flaps, and High Lift Flaps, Turbulent Aircraft Drag Reduction, 100HP 300MPH Natural Laminar Flow Aircraft Design Calculations, List of Important Authors and Useful Books. No Other Book Like This One!
DescriptionPart No.PriceBuyPERSONAL AC DRAG REDUCTION13-12255$30.00 AIRCRAFT PERFORMANCE IMPROVEMENT ARTICLES & LECTURES The Collected Aircraft Performance Improvement Articles and Lectures of Bruce Carmichael 1974-2000 1st Printing 2007. 14 articles. Oshkosh Appraisal, Laminar Wing & Fuselage Design, Propeller Place, Performance Revolution and Improvement, AR-5 & VMax Probe Study, 7 Lectures on Drag Fundamentals, Body Drag, Realm of Reynolds Lam., Aircraft Search, Lam Aircraft Odyssey, 100% Laminar by Suction. 203 Pages. DescriptionPart No.PriceBuyThe Collected Aircraft Performance Improvement Articles & Lectures13-05022$30.00

A Review below:

Personal Aircraft Drag Reduction

by Bruce H. Carmichael

(Published and sold by the author, 34795 Camino Capistrano, Capistrano Beach, California 92624, USA: 1995)
195pp, 195 illus., 26 tables, refs. Photocopy, 1/c, Velobound. US$25 postpaid in USA,$28 Canada, $33 Western Europe,$35 elsewhere.
Reviewed by F. Marc de Piolenc
This reviewer has spent a good deal of time searching for a better title for this book, since limiting its application to personal aircraft seems to deny its much wider usefulness. This compendium of aerodynamic design guidance (and rare, sometimes unique data) by a widely recognized authority in the field deserves a more sweeping title.
True, it does emphasize low-subsonic Mach numbers and low to medium Reynolds numbers, and discussion of powerplant installation drag is limited to air-cooled piston engines, but the sophistication of some of the aerodynamic drag reduction techniques is well beyond the skill of most personal aircraft builders. This book is (with the exception of one acknowledged omission) a design manual for the ultimate low speed, high efficiency airplane, if the designer chooses to use it that way. It is in any case much more than a set of cookbook recipes for a cheap weekend flier. A military contractor working on a long endurance, high altitude reconnaissance airplane will find material useful to him, as will designers of pylon racers, CAFE competitors and others who are fighting installed-power restrictions or seeking the ultimate in aerodynamic performance.
The organization of the book reflects the author's cognomen of "Mister Low Speed Aerodynamics," his long-standing interest in laminar flow design and his determination to apply to flight articles concepts thought by many to be laboratory curiosities.
Beginning with a historical review of research aimed at enhancing external laminar flow, completed by an interpretation of trends in this field, the author goes on to offer examples of actual, flying aircraft incorporating drag reduction techniques that he advocates. There follows a section entitled "Drag Concepts" explaining the various tools available to the designer for measuring, comparing and estimating drag. While the rest of the book emphasizes reduction of parasite drag, this section necessarily considers the contribution of induced drag to the total drag of an airplane, both to give a complete picture and to give the reader an idea of the relative gains from reducing one or the other type of drag.
"Some Performance Considerations" defines a Universal Performance Function, considers the effect of drag reduction on the top speed of both propeller- and turbojet-driven airplanes and considers the "climb-out problem."
This is followed by a compendium of laminar flow wing experimental data, prefaced with a discussion of the significance of Reynolds number and a comparison of theoretical airfoil drag prediction to wind tunnel results. This section covers only "natural" laminar flow, achieved by shaping the airfoil section for the longest possible "run" of favorable pressure gradient. The following, brief section covers all-laminar wings, where laminar flow is maintained artificially by suction. The author then briefly discusses the influence of three- dimensional effects on wing performance and the design of high lift devices. A wing optimization study then compares the minimum drag area of a reference aircraft with flaps and without flaps.
The section that follows contains data unique to this book. It concerns low drag bodies suitable for use as aircraft fuselages, and capable of achieving long runs of laminar flow. Again, theoretical considerations are followed by masses of experimental data on low-drag bodies culled from the author's extensive work in this field. Surprisingly, the effect of body shapes on static aerodynamic stability is also considered in two subsections on body yawing and pitching moments. All-laminar bodies using suction to stabilize the laminar boundary layer are briefly considered. The section ends with a body drag optimization study based purely on natural laminar flow.
Tail surfaces are considered next, primarily from the point of view of minimizing control surface profile and parasite drag. Trim drag (the induced drag of the stabilizer or fin) is considered here only briefly. The thrust of the section is to guide the reader to a stabilizer design of minimum surface area and thickness.
The author then delves fearlessly into an area of aerodynamic design with a high voodoo content - component interference drag. Drawing on his own experience, Carmichael assigns it firmly to the parasite drag category, contradicting some eminent authorities. Having defined the source of the drag, he justifies his assertion by reference to experimental data and lists the many successful remedies applied. He also discusses one obscure and intriguing example of favorable wing-body interference.
The next section, on cooling drag, is perhaps the most frustrating to the reader. On the one hand, the author claims that a large portion (10%-30%) of engine power is consumed in keeping the engine cool, as against the 2-4% theoretically required, suggesting that great gains could be made in this area. He then disclaims experience in abating cooling drag and offers a brief discussion of inlet and exit design, a cursory discussion of internal flow losses, and eleven references. The author's discussion centers on aircooled engines with conventional cooling arrangements, but some of the references include treatment of liquid-cooled engines and the use of exhaust-driven ejectors to induce cooling air flow.
"Practical Problems and Solutions" covers the problems that face constructors attemping to realize long runs of natural laminar flow in real aircraft. It is as satisfying, despite its brevity, as the preceding section was frustrating. Here the author's rare combination of theoretical understanding and practical experience combine to make a rare treat for the reader. After the usual discouraging exposition of the influence of waviness on flow transition on a flat plate, he presents the results of flight experiments at Northrop that clearly showed that real flows over actual airfoils are less sensitive to waviness than flat-plate data would indicate. What is more, the trend with increasing Reynolds number shows allowable waviness decreasing less quickly than for flat plates. Both findings provide solid encouragement to builders. More valuable and equally encouraging data on steps and gaps put natural laminar flow design squarely inside the realm of practical construction, even - with great care - on metal wings.
"Adverse Influences in Flight" discusses the influence of tractor propeller slipstream, noise and vibration, atmospheric turbulence, icing, rain and insect contamination on the performance of laminar light aircraft.
"Refinement through Flight Test" picks up where most design texts leave off. Answered here is the question of what to do when a new airplane's performance does not meet expectations. As one might expect of a long-time soaring pilot, the flight test methods presented emphasize zero-propeller-thrust (engine running) glide tests and gliding tests with the cooling system sealed. Also covered are flow visualization tests using tufts or oil films. The references in this section are especially numerous, varied and useful. The techniques are well within the reach of serious and careful amateurs.
In "Conceptual Laminar Flow Design," all the foregoing considerations are reviewed and their influences on design considered. Two aircraft - one actual (the Teal, designed by Carmichael's mentor Ed Lesher) and one conceptual (Lars Gietz's Vmax Probe, currently under construction) - are used for illustration. The author presents a full drag "buildup" (estimate) for Gietz's machine, then compares it with actual figures from the Teal, taking into account differences in design and design goals.
The final section is not about laminar flow at all. It concerns Fabio Goldschmied's ingenious and controversial proposals for large suction bodies that achieve staggeringly low drag with fully developed turbulent flow. On such bodies suction actually increases skin friction drag, but also lowers the pressure drag of the body. (At higher suction flows, the "drag" becomes negative, i.e. the flow control system becomes a wake-ingesting propulsor.) The Griffith airfoils get a similar, illuminating discussion.
Summing up impressions of this book, disappointment in the cursory treatment of cooling drag is balanced by relief at the author's reluctance to pontificate outside his avowed fields of competence. This book, plus selected references, should provide an alert designer having a basic knowledge of aerodynamics with a solid "core curriculum" in high efficiency, low speed airplane aerodynamic design. What is deeply regrettable is the crudeness of the book's typesetting, page layout and printing. The text is output on a dot matrix printer in a two-pass, blocky sans serif face that is very difficult to read. The illustrations are pasted in, not scanned. The line drawings, most of them prepared or replotted by the author, are clear and well organized. Unfortunately, photos and heavy solids are not halftoned, making many photos unreadable (e.g. tuft and oil film flow visualization photos). The book is reproduced on a high speed electrostatic copier and velo-bound. One could reasonably ask for better quality than this, as desktop publishing equipment and software are now within easy reach of most. In particular, an adhesive binding that could open and lie flat would have been welcome, and would have added nothing to the cost of the book while enhancing its readability.
Addendum, September 1996: The author has made extensive revisions for the new edition of the book. The typeface has been changed to a more pleasing design (although output is still on an impact printer); key photos have been halftoned and are much clearer, and the new edition is perfect-bound with a wraparound cover. There is also new material on current low-drag aircraft projects.​
Considered only as a compilation of research data, this book is a bargain when its price is compared with the cost of finding the data. It would be difficult to assign a dollar value to the author's lucid exposition of theoretical concepts, his insights into the data, his well-organized and well-labeled plots and graphs, and his care in making the book "amateur-friendly" by avoiding the use of formulas. Fortunately, we don't have to, as these features can be considered free supplements to an excellent compendium.

George

#### pwood66889

##### Well-Known Member
"...the sophistication of some of the aerodynamic drag reduction
techniques is well beyond the skill of most personal aircraft
builders."

Probably says it all, George. If it can't be built, it can't be
flown.

#### Topaz

##### Super Moderator
Staff member
... The typeface has been changed... (although output is still on an impact printer);...

:speechles:speechles:speechles:speechles:speechles

#### Norman

##### Well-Known Member
Supporting Member
Yes, it looks like the text was printed on a dot matrix printer and the graphs (hundreds of them) were put in by old fashioned cut and paste. So what! The publication date is 1995, that's about the time I got my first ink jet. Considering his age I wouldn't be surprised if he lots of old equipment. How dose that affect his 50 years of research?

#### wsimpso1

##### Super Moderator
Staff member
It was printed on a dot matrix printer... So what?

Good book, lots of good info. Useful? Maybe not. Educational? You bet. And you get to choose.

Billski

#### Topaz

##### Super Moderator
Staff member
It was printed on a dot matrix printer... So what?

Because this is what I do professionally. It's like someone telling you that they're doing engine design on an abacus. Sure, maybe they can get the same numerical results, but it's hardly the professional method. If they came to you with a sheaf of handwritten pages showing their results, you're going to make a judgement about the quality of the work, just based upon the presentation. Carmichael's book is a respected source of information. Presenting the information the way he's doing is like putting one of Michelangelo's works in a paint-by-numbers book.

That's the subjective reason. There are three objective reasons:

Type set this way really will be harder to read, and the point of a book is to be easy to read. You're trying to convey information to your audience. Anything that stands between them and your information is bad, including poor typography.

If the book were for sale in bookstores, he'd be losing sales just because of the look of the pages. People really do judge a book by its cover - and by the look of its pages. Is it right? No. Is it what happens? Yes.

The other matter is that in this day and age, it very likely cost him more to get it done from the impact-printer pages he created himself than if he'd hired out to get it done right. The transition from his hard-copy pages to a press requires a step to transfer the page images either to digital, or to film if the print vendor is as old-fashioned as he is. That's going to be expensive. Even if he's getting them printed xerographically on a Docutech or somesuch, the pages still have to be scanned into the machine and manually adjusted for brightness and contrast. If he'd done (or hired to have it done) right from the first step, he wouldn't have that cost at all - the file (usually a specialized form of PDF) goes straight into the machine and is either printed directly (in the case of xerography) or etched directly to plate in the case of offset printing. Costs drop dramatically and the finished product is far superior.

Look, I have Strojnik's books and most of Roskam's. They're done on a typewriter and then transferred to press, so the pages are almost as horrific-looking as what we're talking about here. While they contain a lot of valuable information and will remain in my library forever, you can't say they're as easy to read as, say, Raymer's books, for example. Part of the reason that I reference Raymer so much more than Roskam is that I can simply get the information from his books more readily. Part of that is his writing style. Part of that is the clean and well-typeset "look" of the pages - they're just easier to read.

Last edited:

#### Topaz

##### Super Moderator
Staff member
...How dose that affect his 50 years of research?

The research? Not at all. The way his research is perceived, quite a bit. He'd sell more if the book looked better. Engineers hate to hear that, and I understand that a "good idea is a good idea, regardless of what it looks like", but not everyone who might purchase this book will feel that way, and they're perfectly justified in their method of selection. Not everyone thinks like an engineer, and no, this book isn't only being sold to guys with Aerospace degrees, as evidenced by this conversation in this venue. To most of the rest of the world, how something looks is just as important as how it functions. Call that shallow if you want, but most of the world feels that way. And they're writing the checks.

Last edited:

##### Well-Known Member
Supporting Member
We should collect a list of the real home-published treasures and offer the authors/estates to do a polished publication of them. Make sure that their income per copy doesn't go down, basically do it as a non-profit thing just to make the resources more widely available and more accessible.

#### Topaz

##### Super Moderator
Staff member
I'd have to cover my costs for time and lost-income for other work, but I'd really enjoy working upon projects like that. It'll be a shame when some of these books disappear.

##### Well-Known Member
Supporting Member
Hmm... Shall we start a thread to collect the list of books? Criteria: (1) self-published; (2) audience limited by presentation or availability due to (1); (3) contains information valuable for aircraft design/building and not available elsewhere.

#### gschuld

##### Well-Known Member
I'd like to see an up to date and more professional version of Paser's Speed with Economy.

I'd also like to see a book of light aircraft related CAFE articles and studies, complete with nice diagrams and pictures.

I'm going to give Bruce Carmichael's books a go. I'm more interested in quality theory and reference than quality publishing, but I agree with Topaz that it sure wouldn't hurt getting the average Joe to take it seriously if it presented and read well.

George

#### Topaz

##### Super Moderator
Staff member
Hmm... Shall we start a thread to collect the list of books? Criteria: (1) self-published; (2) audience limited by presentation or availability due to (1); (3) contains information valuable for aircraft design/building and not available elsewhere.

Might be a good thread to get started before we drift too far away from this one.

##### Well-Known Member
Supporting Member
Fine, fine, I'll do it. Here.

#### Apollo

##### Well-Known Member
....It'll be a shame when some of these books disappear.

I've searched the Internet for Bruce Carmichael's Personal Aircraft Drag Reduction and it seems this book is no longer available. Aircraft Spruce no longer sells it; it's out of print at Amazon, etc. Sent email to Bruce's AOL address and it was undeliverable. I have an old phone number and will try calling him tomorrow.

Does anyone know where this book can be purchased today? I'd certainly like to have a copy.

#### Norman

##### Well-Known Member
Supporting Member
I heard that Bruce stopped construction on his airplane due to health problems several months ago. He used to sell his books out of the trunk of his car at TWITT meetings in El Cajone. As far as I know he's still a member so the president, Andy Kecskes, would probably be your best bet to find the book (Bruce's books are still advertized in the newsletter) You can get a message to Andy at [email protected] <[email protected]>

#### Tom Nalevanko

##### Well-Known Member
Books by Bruce Carmichael: 34795 Camino Capistrano, Capistrano Beach CA 92624. 949-496-5191

The above was in the Classifieds section of the most recent Sailplane builder (SSA/ESA). Hope it helps....

Blue skies,

Tom

#### topspeed100

##### Banned
Is there a really good book store here in Europe where all good books can be bought...or do you really have order everything from here and there ? Is there an all around aviation book store in continental United States ?

#### Apollo

##### Well-Known Member
Books by Bruce Carmichael: 34795 Camino Capistrano, Capistrano Beach CA 92624. 949-496-5191
Thanks, Tom. That information is correct. Both of Bruce's books are still available for \$30 each (send cash or check) for delivery in the USA. He doesn't do email and who knows how long these books will continue to be available. IOW, buy it now