Saturday, July 19, 2008

The Orphaned Engine

Most Experts Aren’t. That's something the late Smokey Yunick said back when I was a seaman deuce. Every month my mail delivers one or two messages saying it's still true. The messages usually come from some superbly experienced fellow who has literally spent his life working on cars or trucks. He is the Local Guru when it comes to engines for homebuilts and he's taking the time to let me know that the automotive engineers I like to cite in my articles aren't quite as bright as I seem to think they are, offering an experience-based example to prove his point.

Unfortunately, the offered example invariably deals with cars or trucks, things in which the fellow has a life-time of experience, whereas automotive in the sense used here, does not, although it could include them. To an engineer, automotive means something that can move under its own power. Like an oil tanker, the Space Shuttle, or a gold dredger.

My usual reaction is to hit the delete key. I get more mail than I want, most from people with real problem, some of whom I can help. But it's always sad to hear smart people say dumb things. And on the whole, these are smart people, even though a life-time of experience hasn't tipped him off that we're taking about two different meanings for automotive.

We all start out pretty dumb. As we age we gather information and gain experience and, assuming a fair share of native wit, we end up a bit smarter than when we began. Mebbe all this guy needs is a nudge in the right direction. So you say hello and the odds are the fellow is having the same problems as everyone else except he was a bit too proud to say so.

With this type of Expert you'll often discover his life-time of experience has been with just one type of engine or perhaps one type of car and he has been trying to transfer that experience to a Corvair or a Volkswagen and isn't having much luck. I mean, who ever heard of a head torqued to only eighteen foot-pounds! That has to be wrong... right?

If the fellow hasn't figured out the meaning of automotive there's a good chance he won't have any idea in the blue-eyed world about Class of Service but a good understanding here is the real key to a successful conversion so you give it a shot.

A car or light truck uses a variable speed, high-rpm, low-torque engine whose nominal output approximates 25% of its peak output. Nominal output is defined as the amount of power the engine was designed to deliver for approximately 98% of its service life. The only time it’s expected to produce more… that wayward 2%… is when accelerating or climbing a hill. Once on the flats -- once you've reached a Stable State of cruise -- the figures are a good match. For hilly regions vehicle manufacturers offer different ratios for the rear-ends. Economy takes a hit but over-all, the figures match up. Respect an engine's Class of Service and you'll be rewarded with 2,000 to 5,000 hours between overhauls.

You can always demand more output from either type of engine but doing so will reduce it's service life. With a converted VW, for example, your Mean Time Before Failure will typically fall from about 2,000 hours in vehicular service to about 200 hours when powering a plane.

By comparison, an aircraft engine is a single-speed, low-rpm, high-torque engine whose nominal output approximates 75% of its peak output. Peak output may be defined further as maximum sustainable output, and as Peak-sub I, meaning an instantaneous value or dyno blip, something you might use to impress the newbies.

Since our goal is to produce thrust throuigh the rotation of a propeller, our primary interest is in the amount of torque that appears in the crank, and in the propeller's efficiency at a given rpm. The measurement of thrust is quite simple and articles describing different types of homebuilt thrust stands have appeared in the literature and on the internet. You will note that horsepower, which serves no useful function at this stage, has not been mentioned.

It usually takes an exchange of half a dozen messages or thereabouts to arrive at this point, if in fact we arrive at all. In the overwhelming majority of cases the Local Expert simply vanishes. Which is doubly unfortunate because the best is yet to come.

When we convert an auto engine for use in an airplane we are trying to convert it from one Class of Service to another to make it more suitable, usually in the area of mechanical reliability. By comparison, the typical flying Volkswagen starts out as a marginally suitable auto engine that is then made even less suitable for aircraft use by turning it into a hot-rod enigine. Why? Usually because the person doing the conversion has little understanding of an aircraft powerplant. Indeed, most such experts are merely the local Guru grown old, selling dune buggy engines to the kiddies. And after all, it does fly the plane, right?

So why even bother.

Well.... because we should. A properly built engine is more efficient. It produces the required torque at a lower rpm and wear increases exponentially with rpm. That means a properly built engine uses less fuel to deliver the same thrust and last longer, too.

But a properly built engine is also a lot less expensive to build and nowdays that's becoming a critical factor.

See that chart down there? The one title BORE VS STROKE? (It's embedded in the article in the blog; you guys on r.a.h. will have to go dig it out and print yourself a copy.) The chart shows the bore & stroke combinations for most common conversions and for everything using 88mm jugs or larger, or a 78 mm or longer crank, is going to have to machine the crankcase & heads to match. What they'll end up with is a dune-buggy combination -- a high-rpm engine that produces most of its torque up high. Itty-bitty toothpick of a prop. Not very efficient at all. Lots of machining to do. Lots of tricky bits to go wrong during assembly... which is why some folks don't even offer the thing assembled.

But it's all a bit of a joke because no matter HOW BIG the engine, it's MAXIMUM SUSTAINABLE OUTPUT is going to be between 35hp and 45hp.

Yeah, I know -- everybody is selling 80hp and up. Which is a dyno blip, not a steady output. Lotsa cubes is going to get you out of the weeds quicker but once you get the puppy cleaned up you're flying behind your basic 40hp engine, depending on the local atmosphere.

The limitation has to do with the heads, not the displacement. The cylinder heads only provide enough fin-area to manage the waste-heat from about 40hp. Unless its nice and cold or you are nice & high. But the dune crowd only knows how to build big-bore strokers.

Now go take anohter look at that chart. Limit your jugs to the stock 85.5mm.s and your cranshaft to a 78mm. At those sizes there's NO MACHINING REQUIRED. Your displacement is 1791cc, your maximum SUSTAINABLE output is about 45hp and your peak torque is going to come in at about 2800rpm.

Did I mention that no machining is required?

You've altered your cam timing but you're running a stock cam or a Schneider 'chugger,' the one used in the orchard-blower engine. You're running SINGLE PORT HEADS... because you're now an airplane engine, not a hot-rod. Your Volumetric Efficiency is pushing 70% and you're about a $1000 dollars ahead of the game because you haven't had to buy all that machining and you're using a higher percentage of stock, off the shelf parts. You're also running a longer, more efficient prop -- hopefully one you've carved yourself.

The thing starts on the first flip because it has an efficient ignition system, one that automatically adjusts itself to the load and a 20A. electrical system. But no starter, please. As it is, it weighs about twenty pounds less than any engine offered by anyone else.

But of course, it's not a dune-buggy engine. And the Instant Experts will stand in line to damn it with faint praise for that fact alone even while it flys circles around them and is still going strong when they're doing their second valve job of the year.

In my opinion, this is the perfect engine for an aerodynamically clean single-seater, like Bruce Kings little beauty. Had fate dealt me a different hand, that's what it would be going into. It would also be a good match for a KR-1, the early Jodel, Druine, the Teenie Two and similar designs.

Kill the parent, you got orphans. And that applies to engines, too.

-R.S.Hoover

Tuesday, July 15, 2008

Cancer's End-game

Multiple Myeloma destroys bone; it literally eats it away, usually starting with the lower spine. But the cancer itself is a disease of the blood, similar to leukemia. Since we start out with a lot of bone, the cancer may chew away on us for years before it's symptoms become obvious. After all, everyone complains of a sore back now & then.

Being a disease of the blood, myeloma is highly mobile. Soon after the cancerous cells appear, they begin to spread, attacking the bone at new sites, which explains the multiple part of its name. Once established and able to spread, there is no cure. On average, you've got about three years to get your house in order.

Although there is no cure, radiation and a number of drugs have proven effective in slowing myeloma's spread. If the bone damage has not been too severe such treatment may buy you some time. Unfortunately, once attacked by myeloma our skeletons can not mend themselves. Some drugs are able to strengthen the remaining bony structure but rarely to the extent needed for pain-free mobility.

As you know, this all pretty new to me; there may be factors I've completely overlooked. But it wouild appear that working out a careful strategy of treatment offers a strong probability we can stabilize the affliction sufficiently to buy the time needed to finish a favorite project or to wrap up our affairs.

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I'm receiving radiation therapy at the local Cyberknife clinic, a neat little facility just minutes from our home where a computer-guided x-ray machine is used to kill the existing tumors a slice at a time. Doing so isolates the lesions and reduces the pain and no matter how you slice it, this story is really about the pain.

The location of the tumor(s) having been identified by prior x-ray and MRI scans, three dots of radio-opaque ink are tattooed on your belly allowing the system to realign itself with an accuracy of better than half a millimeter. The initial programming has defined the tumors as targets, determining the optimum amount of energy to deliver on each of three axies so as to limit the amount of damage to the healthy tissue. Hit the big red button and the system delivers its lethal barrage at the rate of several thousand hits per second, each precisely on target using feed-back from a separate x-ray camera to keep track of its progress.

The sessions, which are painless, take about fifteen minutes. They have scheduled one per day for the next couple of weeks with the option for a bit of sniper work toward the end.

At the same time, the physicians have been working out a chemical attack to compliment the radiation barrage. X-rays and other forms of imaging provides some of the feed-back needed to guide the chemical attack but the most useful information is derived from a series of vampire strikes to monitor the chemistry of my bloodstream. These procedures are slower than the dramatic strikes from the Cyberknifes linear accelerator but infinitely more subtle, capable (in theory) of tracking down a single cancerous cell.

-R.S.Hoover

Thursday, July 10, 2008

Doing Your Vitals

'Way back when, a lot of teachers were also nurses. Mrs. Doyle was one such lady who returned to teaching Third Grade and serving as the School Nurse during WWII, when we simply didn't have enough pople to go around. But there was a war going on and rather than just talk nursing, Mrs. Doyle taught it, starting with basic health. She gained our respect by producing an antique sphygmomanometer from an equally antique Black Leather Bag and commenced to give the whole class a tune-up. Indeed, she was not satisfied until the whole damn class had learned how to determine Blood Pressure. But that's just the tip of the iceberg. When you say vitals the implication is that you are recording:

Blood Pressure
Pulse Rate
Respiration Rate
Body Temperature
Height
Weight... and so forth.

That last ...and so forth... looks unscientific as hell but it makes sense to a kid. Along one wall each student had a list showing our body weight, height, color of hair & eyes and several other data elements, some not specific to human vital signs but all of profound interest to a gaggle of eight year olds.

Even more interesting is the fact we collected the data ourselves. And if you think that's a Big Deal, it's not. In fact everyone should be able to not only define their vitals but should have no trouble collecting such data and recording it in a tabular fashion.

Because that's what you do when you get sick.

Ecept nowadays, most folks don't. In the modern world you simply plug yourself into your computer and let it collect your vitals automatically. That guarantees less chance of making an error when you collect the data but it also ensures more uniform reporting. It also guarantees the data will be communicated to whoever needs it.

Which is why you could have knocked me over with a feather when a local 'health care worker' shows up to 'record' my vital signs.

Mebbe when digging the Panama Canal but definitely not in the 21st Century. By the time the 'health care worker' has driven to your home, imposed themselves on you, recorded your vitals -- correctly, I hope -- you are looking at a significant cost in time and gasoline.

-R.S.Hoover

Saturday, July 5, 2008

Cancer

Yes, I've got it.

No, you can't have it. You have to grow your own. You don't catch cancer. It's not a head-cold or a case of clap. I've been working on mine for more than five years now. It's called Multiple Myeloma and it has lead me a merry chase, partly because the first symptoms appeared as a kind of transition variety and all those fancy, infallible scanners and CATZ and PETZ and sooper-dooper hi-teck never-wrong space-age machines were DEAD WRONG. Indeed, I was I was healthy as hell according to them... and they were right. Unfortunately I was in the process of developing multiple myeloma so that while I was healthy then, within a matter of weeks I was now not... even though I had just completed a series of expensive, time-consuming tests that said I was.

One of the trickier bits about Multiple Myeloma is that it likes to attack people who are about forty years of age or older. Need I mention that includes a lot of pilots?

If you just found out you've got it, you're one of about 15,000 others in the 40 - to - 65 age-group who joined that years club. After getting the good news an awful lot of these guys make it as far as the parking lot before blowing out their brains. I mean, after all... they've just lost their ticket, everyone is moving to larger airframes rather than smaller ones and career-wise our boy is on the lower cusp, for whom a lab report ...perhaps accompanied by a friendly tranquilzer... has just guaranteed the world as he knew it has ended.

Okay, stats vary and I don't want it to appear worse than it is but I've had the misforturne to see this scenario played-out twice, up-close and personal. My own situation aside, I'd rather it didn't happen again so howzabout following me through on this one?

The Biggie is that some forms of multiple myeloma are TREATABLE. Okay, so there's no ATR in your wallet when you get done but at least you are still there.

Treatable means you can't have my plane... go build your own. But we -- and I'm talking the aviation community, your family and what all -- we've still got you. That puts us miles ahead of the game. So don't get all teary-eyed on me. You've still got the Big C! (and so do I). It's awful. It F**king Hurts! It's NOT FAIR!!

So suck it up and let's get on with our lives.

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Like I said, some forms of multiple myeloma are treatable and I'm a living example of someone who ha
s just started through the process. I've done the wet hanky bit, hid in the corner for a major bout of boo-hoo's, then then did the Oh So Sorry me but my God that sonofabitch hurts!

Weak as a cat, too. (But I'm working on that.)

Kinda confused. Chemotheropy guarantees you're going to kinda dingy now & then but but trust me, I passes.

What you need, right now and for a good while to come is your friends. And you can go ahead and count me in, if I'm not already on the list. Because with multiple myeloma the emphasis is NOT about grabbing your friends by the handles and dumping them in a hole in the ground, it is about getting BETTER; about HEALING. And I'm not standing here blowing smoke. Hell, I'm still making rigs for Chugger's wing ! (and no tranks in the pill compartment this morning).

(And I've still got three damn engines to finish :-)

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So what about you guys who don't have 'chugger' waiting in the wings? Then you're going to have to get one...
or something damn near identical.

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Plus you've got to learn how to SLEEP.

Deep, rich rewarding SLEEP. Because based on my limited (but growning experience as a cancer victim) sleep appears to be the catylyst for cure -- or at least for healing. The only problem is that everything is all so new (!) and there is so much to learn. To make matters worse you usually look like the dog's dinner and feel even worse.

Tough Darts.


About half the time, multiple myeloma is trying to kill you on purpose and the rest of the time it does a fair amount of damage through pure chance, all the while you are rattling like a goard from all the pills you've stuffed yourself with. Most of the pills are an effort to control the pain, others are there to help control the side-effects of the chemicals that are suposed to help you GET WELL and a very critical aspect of that effort is the need to maintain accurate records. The records are needed to maintain the proper balance between pain management and chemotherapy. Need I mention that if you aren't a good clerk at the outset you'll soon become one!

So what works? What's the Secret Weapon?

I haven't the foggiest notion.

But I do know that Jesus never owned a Cadilliac and Mohammad had never actually seen a real oil well although it's fair to assume both enjoyed a wealth of real friends, the kind you can't buy.

So let's start with that


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29 June -- Home from the hospital, I pretty much lived in this chair for three days & nights because it simply hurt too much to lay down. We finally got that worked out .

You can't deal with the tumor until you've figured out some way to deal with the pain.
















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