Friday, October 27, 2000

Really Give Me Brakes?

Really Give Me Brakes?

We love our cars, and we love to take them to the track. The Quattro Club has been especially good at sanctioning driving school events at race venues across the country. We sometimes hear afterwards of horror stories about brakes being destroyed during these events, tales of near-death (at least to those that had them) experiences. Further, the earlier Audi performance models such as the S4 and S6 had what many owners considered to be inadequate brakes, even for the street. In response to this there’s a significant cottage industry catering to Audi owners for brake upgrades. In fact, one of the more common subjects for articles in the Quattro Quarterly has been on that subject.

As technical director of BIRA (Brake Improvement Research Association – see Quattro Quarterly Fall 2000), I am consistently asked if BIRA (or other aftermarket) brakes are "adequate for track use". The concern seems to be that tracking a street car would kill the brakes, that it's a safety issue that any owner should consider before taking their car on the track. I'm going to toss a completely different spin on this and no doubt start some serious debate on the subject, but in my opinion any brakes that work properly are adequate for track use. Yes, even the stock brakes.

Keep in mind that these track events are not competitions, they're learning events. They are for us to go out and drive our street cars, vehicles TOTALLY inappropriate for track use, around a local race track and go fast(er). No one is going to notice if your car is a second per lap faster than it was last time, or if it's a second a lap faster than your buddy's car. Even if someone did notice, it's irrelevant. If going fast is really a need (or a strong desire) for you, get into organized racing because these Q-club driving events are not for you. Try SCCA (http://www.scca.org) or NASA (http://www.nasaproracing.com). Check your attitude at the Q-Club events door, please.

Since we’re not concerned about the fact that we're driving faster than before, we need to take care of our equipment to be able to enjoy the event. After all, isn't the whole point of these things to have fun? You've heard the old racing saw, "In order to finish first, you must first be Finnish" (oh, wait, that was Mikka). Actually, it’s "In order to finish first, you must first finish." To do this, you must take care of your car and drive within its limits, and that includes brakes. Taking care of the brakes may include slowing down (horror!) in order to make your brakes stay within their temperature limits and last the event's duration. Tell me, who's the guy out there having more fun: the one that drives like a bat outta hell, destroys his brakes in two sessions, and sits out the second day, or the guy that takes care of his car, goes a second a lap slower (not that any will even notice) and makes it the full two days?

I am significantly more impressed by a driver that understands his/her own personal limitations, is in sync (Zen?) with what the car is telling them, and drives appropriately, one that can make a car last for the duration, not have to work on it every session, and stays off the walls. A really good driver can take a totally stock car and go against any of us in the most modded-out Stage 27x car. Count the number of laps they drive over the two or three hours of track time out there, and you'll be surprised that this Good Driver will put in more laps, go farther, have more track time, and thus probably have more fun. Why? Because they are taking care of the equipment.

As I tell my students, "You can't win these events, but you can certainly lose them." The 'lose' part is totally controlled by one major piece of equipment, the MOST IMPORTANT piece of equipment in the car: the nut behind the wheel. That nut has total control over the car's operating parameters, including the brakes. Fancy brake setups, expensive brake fluid, stainless steel lines, big tires, big wheels, air dams and splitters are all meaningless fluff. Since the whole point is track TIME, doing it faster gives us nothing, wins us nothing except maybe a mention on Internet Forums, which will scroll off within a week to be forever ignored in the archives. How much money is that worth to you?

To summarize (and not get off too far on a rant) all this additive equipment is nothing when you consider we're in a non-competitive environment. We get nothing by going faster, and we are all capable of showing the discipline of driving within the car's limits. There's no trophy queen waiting for us on the podium, and there's no Speedvision announcer waiting to interview us. Besides, it's a heck of a lot more fun to make a slow car go fast than to try and make a fast car go fast. Go slow in a stock car and no one notices, it's expected. Go fast in a highly modified car raises no eyebrows, as it's expected. Go slow in a highly modified car and you look like an idiot.

Go fast in a stock car and folks are impressed.

OK, so now that we've gotten beyond this we’ve decided to mod the car anyway, let's say for cosmetic purposes (personal tastes.) What has this gotten us for the track? If we still maintain our discipline and drive within the limits of the car, all we've done is increase those limits to a higher plane.

In context, consider brakes. Before now, we drove within the limits of the stock brakes, and that required that we lift off the gas sooner (horrors!), brake sooner (horrors!), and make sure we cool the brake parts sufficiently before the next time we need it (yeah!). We were paying attention to the car, and noticed that the car didn't really stop well at that last turn, and that it's worsening slightly each time. The Good Driver is saying to himself, "OK, I'm overheating the brakes, and the worsening tells me I'm not rejecting enough heat before the next turn. I need to slow down to save the equipment." We finished the event and had a heck of a time doing it.

So what does adding the Stage 27x brakes buy us? More speed, more kinetic energy, more chances for balling up our little cars into a length of steel Armco. Does going faster make us a better driver? Not at all, I've met a lot of rich race drivers that couldn't drive worth a squat. They sure were fast, though, in those mega-millions cars (ever watch the Ferrari Challenge races? Hah!) Does going faster make us learn more? Nope, it's still all the same idea of driving the right way, at the right locations, all within the limits of the car. Does the Stage 27x brakes eliminate the need for being precise? Not at all; in fact, quite the contrary.

Does the Stage 27x brakes eliminate our concerns for brake system longevity and safety? ABSOLUTELY NOT.

All Stage 27x brakes will do for us is raise the bar a few notches more. You can still overheat the brakes, you can still fade the pads, and you can still wear out the components. All you've done now is raise the SPEEDS at which those failures happen, and increased the outflow from your pocketbook. Remember, raising the bar increases the distance you have to fall when you screw up.

OK, so let's talk about reality.

Our cars are luxury cars that can weigh almost two tons, sometimes more. Since many of us have modified the power in the car in that quixotic Mutually Assured Destruction quest for “enough power” (clue: you’ll never get there), we are capable of some serious speeds on even the shortest straights. Problem is, I don't know of any road course that does not have a turn at the end of a straightaway. So, you’re gonna have to use the brakes.

Unfortunately, all of our cars are equipped with loose nuts behind the wheel; the level of tightening varies. Even though I contend that any disciplined driver can drive these track lapping events with stock brakes, I concede that at the speeds we can drive the stock brakes, while "adequate" with discipline, are not "good". Because the stock brakes are designed for day-to-day driving and the occasional single hard stop from highway speeds, they are not up to the task of repeated stopping from high speeds as is required at these road courses.

So what do you do about it? First of all, you pay attention to what the car is telling you. The first indication of problems is brake pad fade. This is when you've over-heated the brake pads beyond their designed temperature specification, and they start to melt at the surface. This melting transfers the pad's surface to the rotors (and make it feels like they're warped). A melting pad does not have the friction coefficient as good as a non-melting pad; this is noticed as increased pedal pressure and if not kept in check a continued worsening of brake performance. Plain and simple, you've overheated your brakes and the only resolution is to SLOW DOWN and not use the brakes so hard. Many nuts think that they've boiled the brake fluid; this is not usually true. It is hard to boil brake fluid in a stock car with stock brakes. The pads will always fade first and since a fading pad is not generating as much power, it's not generating as much heat.

A loose nut will continue to drive hard, won't back up the stopping point, and will eventually completely slag the pads to the backing plates until Loud Noises begin to happen. Or, a loose nut will not compensate for the increased braking distances that come with fading the pads. In either case, if the nut doesn't do something quick (like, maybe go home) Mr. Armco awaits.

So, because our brake pads are made for normal everyday driving, I think it's a fine idea to have a set of pads purchased specifically for driving your car around a race track. This will allow you to do spirited driving consistently lap after lap, within limits. Anything over and above this, including BIRA designs, is for speed, not for safety. And I think you got my point on more speed at lapping events...

OK, so there we are. Greg thinks that all stock braking systems, with aftermarket pads and a properly tightened loose nut, are “adequate” for track use. If you want some bigger brakes over stock they are by definition certainly adequate for the track and will make you go faster, if that's important to you, subject to the laws of Physics and Thermodynamics. However, it's even possible for a heads-down loose nut to over drive aftermarket brakes to infamy, and I bet that even the “best” megabuck brake systems can be burned to a crisp in short order. However, for those same megabucks I can throw a pretty nice beer party after the first day's event. That will slow down my "competitors" a whole bunch more than aftermarket brakes will speed me up, and I’ll be more popular to boot!

Friday, August 25, 2000

On Grumman Tigers

Following is a letter that I sent to Aviation Consumer in response to their request for information on the Grumman AA5-B Tiger. They used a large portion of it in their December 2000 issue.

25 August 2000

Aviation Consumer
via email

Hello, Paul. I'm responding to your request in the September issue for owner information on the Grumman AA-5 series.

I'm the owner of a 1977 Grumman AA-5B Tiger (details at http://www.gatm.org/flying). I'll tell you right off the bat that I am not objective on the subject, that I find the Grumman line of light aircraft to be one of the best values out there.

I learned about the Grummans soon after I got my pilot's license. I was doing some local post-PPSEL check flight air work with the FBO's Cessna 172 and I landed at Bridgeport, CT. As I taxied back for departure I passed by Carney Aviation (http://www.carneyaviation.com), a club that flies Grummans and a couple of Mooney 201s. I saw the Grummans and thought they were attractive airplanes; I pulled over to learn more about them. Within an hour I was taking a familiarization flight in a Tiger; within the hour after that I had returned the FBO's C-172, rarely to ever fly one again. I joined Carney's flying club on the spot and have been flying Grummans almost exclusively since.

I bought my own Tiger less than a year later, and it's been a wonderful experience. I've flown about 850 hours in my Tiger over the last 5 years, it supported me through my IFR training, and it's taken me all across the continent. I fly it IFR and VFR for work and for pleasure.

My initial attraction to the Tiger was visual: I think the airplanes are darn good-looking. Sleek lines, smooth surfaces (no rivets), and the slide-back canopy makes you look like the P-51 Mustang pilot you want to be. Flying the Tiger seals the deal: the handling supports the performance flying expectations. The airplane responds to your touch with very little resistance, and is simply a joy to fly. The Tiger's handling is to a Cessna 172 as the Mazda Miata is to the Ford F-150 pickup truck.

The Tiger carries a full load of four adults and plenty of fuel. My Tiger's usable load is 950 pounds (1450 pounds empty weight on a 2400 pound gross weight). I can load myself and my wife, my brother and his wife, weekend bags, and still be able to drop in "fuel to the tabs" of 38 gallons. If it's just my wife and I flying, the full fuel load of 51 usable gallons will allow us to fold down the rear seats to reveal a six-foot-long cargo area, drop in two full-sized bikes and all our bags, and off we go for 4 hours or more of flying with reserves (which is more than she and I can stand anyway!)

The instrument panel of all Grummans (including the AA1-series two-seaters) uses the standard-six arrangement of gauges and is large enough to accept just about any and all instruments and avionics that you care to stuff in there. Despite that, the panel's position is much lower compared to other GA aircraft, giving the pilot a magnificent view through the large windshield and side windows. The view from inside Grummans has been compared to that of the full-bubble canopies of fighter aircraft (like the P-51...?)

To be frank, one of the biggest attractions of the Tiger is its speed; even though I can afford more airplane I remain in a Tiger because of its ability to fly relatively fast on a reasonable budget. I've done a number of STC-approved modifications to my Tiger, most obviously the new LoPresti GTO Tiger cowl. The "book" says that I should be able to fly 139 KTAS at 8000 feet at redline (2700 rpm maximum-continuous) using 10.8 gph, and I can match (and beat) those numbers easily. I consistently flight-plan for 135 KTAS and I'm never disappointed. Should I decide to push the throttle in a bit further, I'll see low-140s TAS at 12 gph. This is with a 180-horsepower Lycoming O-360-A4K, fixed-pitched prop, and fixed-gear! I just love getting called as 6 o'clock traffic to constant-speed-prop, retractable, 200-hp Piper Arrows!

Despite the fact that Grummans have been out of production for over 20 years (not including the 90's variant, the AG-5B) parts and support are plentiful. I have effectively done a complete restoration of my Tiger over the last 5 years and I've never wanted for parts. Fletchair (http://www.fletchair.com) has been absolutely fantastic in supporting our aircraft. They are the absolute best, even to the point of getting PMA approvals for parts as the old-stock supply diminishes and the demand increases. Owner-to-owner support is provided by the marque club, the American Yankee Association (http://www.aya.org/), and by the Internet-based support group, the Grumman Gang (http://www.grumman.net/). Without each of these avenues of support the owner experience would not have been anywhere near as enjoyable.

Not that the Tiger needs a lot of repair. The basic aluminum honeycomb tub is ox-strong and doesn't need maintenance. The rest of the airframe is aluminum glued together, and despite a brief period of "bad glue" in 1975 the airframe is one of the stoutest around. Rudders and elevators are cable-operated; flaps are torque-tube operated and the ailerons are a combination of torque tubes and cables. None of these need maintenance and repair over and above the standard annual inspection.

The Grummans are blessed with a non-oleo nose strut with a castering nosewheel (now becoming de rigueur in high-performance experimental aircraft) that is a joy to operate. Using differential braking allows the Tiger to spin upon itself and make a 180-degree turn inside its wingspan. The non-oleo main landing gear is fiberglass laminate and is quite effective at absorbing even the worst landings (thus its original "Face Saver" landing gear moniker.) All of the remaining systems (electrical, brakes, avionics, engine, prop) are standard-issue items with their associated plusses and minuses.

Like other aircraft, Grummans have their spat of specific minor issues, but because of the simplicity of the airframe the AD list is thankfully small. All one-time ADs on standard aircraft parts (mags, air filter, seat belts, oil cooler, carb, your various Lycoming ADs) should have been complied with by now. There is a recurring visual aileron inspection every 100 hours for the Tigers, and the wing attach bolts need to be inspected (effectively, replaced) every 500 hours. If the aircraft has not been STC-approved to a Sensenich prop from the original McCauley, then the McCauley must be dye-penetrant-checked every 200 hours. In addition, the McCauley prop carries a yellow-arc "do not fly with power back" range which coincides with most IFR approach flight. However, a large portions of the Tiger have been converted to Sensenich props.

Finally, the cost of ownership and operation of my Tiger is exceptional. Minimal annual inspection costs ($750 basic annual inspection cost if I just drop off the key) assuming a maintained airplane, 11 gph fuel costs, and insurance costs of about $1300 annually (I'm an IFR-rated pilot, 150 hours per year, about 950 TT and I participate in the Wings program every year.)

If you're looking for a little less entry fee and performance but just as much fun, you'd do well to find a Grumman AA-5A Cheetah. The Cheetah is very similar to the Tiger (it's almost the same airframe), except it has a 150hp Lycoming O-320 engine as compared to the Tiger's 180-hp. That 30 hp difference drops the top speed about 15 knots, the gross weight to 2200, and reduces the climb rate making it a close call for filling up all four seats. There are STCs available to raise the compression of the Cheetah to that of the 160hp O-320 engines, and owners report that it "simply transforms" the Cheetah. I know of several high-compression Cheetah owners that claim they can keep up with the slowest "dirty" Tigers...

The final jewel in the Grumman four-seater crown is the AA-5 Traveler. Built from the early-70s until the debut of the Cheetah in 1976, the Traveler is a fine 150-hp airplane. As capable as any Cheetah (but slightly slower due to less-sleek aerodynamics) the Traveler can be had for bargain prices and offers the Grumman-standard handling, good looks, and bargain speed. The hidden treasure in the Grumman line is the 1975 AA-5 Traveler. This airplane was the "crossover" airplane when Roy LoPresti (then employed by Grumman American) was transforming the Traveler into the Cheetah and the Tiger. The 1975 Traveler got all the wing, gear, and nose aerodynamic cleanups of the Cheetah while keeping the smaller Traveler tail -- and the less-expensive Traveler name. "A Cheetah by any other name" might be the killer compromise.

If you need to fill up all four seats with a lot of fuel and speed, then the Tiger's the way to go. However, if your typical mission is to only fill 2 seats with baggage and fuel for 4 hours at a sippage of 8 gph, while still flying faster than the others, then the Cheetah or the Traveler is the better choice.

There are no downsides to the Grummans: sporty handling, great looks, good economy, bargain speed, and good load-carrying capabilities. If you need to carry big game out of the Alaska tundra, you're out of luck with the Grummans. If you need to go faster than 145 knots or you gotta have those extra white and blue knobs, you're out of luck. If you want to fly in the flight-levels, you're out of luck. But, if you want a fast, sporty, attractive passenger light airplane, you'll be hard-pressed to beat the value of a Grumman!

Greg Amy