Plane Speed: How Fast Do You Need To Fly?

Even though the aviation world is largely one of knots and not miles per hour, when it comes to speed, some of us still think in terms mph. For years, manufacturers were the worst offenders, especially Mooney, which made the 200-mph such a goal that it named one of its planes the "201." And we admit that 200-mph looks a lot faster than 175 knots, even though they're just decimal points apart in actual value. Though it's lost a lot of its luster over the past couple of decades, in general aviation, 200 mph remains a significant marker, a kind of imaginary speed barrier for single-engine aircraft. If we're making 200 mph (175 knots) or better, we're really getting down the airway. With the advent of a number of slippery, big-engine singles, most notably the Cirrus SR22, 200 knots might well be the new benchmark of how fast fast is. There's no doubt but that today's buyers of high-end, high-performance planes want to see that number.

And for the sake of standardization, Plane & Pilot has adopted the FAA's knots-first editorial policy, which for the past 35 years has been an industry standard. And when we discuss speeds, whether mph or knots, we're referring to true airspeed, (technically abbreviated as "ktas"), which is the plane's speed through the air, which is calculated from the calibrated airspeed and adjusting for the variables of air density and temperature.

The big question remains, though. What does speed mean in real terms? What kind of advantages do those fast movers enjoy, and is it worth what you have to pay for it?

The answers are, there are a lot of advantages, some big, some not so big, and the costs can be great. Can they be too great? Good question. Let's look at some real-world cases.

But first, it's important to get a grasp of your typical mission. If your prime travel distance is, for the same of choosing a round number, 500 nautical miles, then one could make a compelling argument that you don't need the fastest of the fast to make that trip reliably and regularly. But unless you're making a permanent move, cross-country trips don't end at the first fuel stop or the eventual "destination." The destination is, in fact, almost always back home. If you're making a multi-day trip, which most long cross countries in a small piston-engine plane will be, regardless of how fast the plane is, then you can treat the mission as two separate trips on two separate days. Fair enough. But if you're planning to be home again that evening, then speed is an even more critical part of the calculus. In fact, without a fast plane, a 500-nm trip out and back again with three hours on the ground at the destination isn't doable in daylight in most of the Lower-48 United States during the daylight available most of the year. And super long days with a trip home late in the evening almost guarantees less than optimal human performance on those last legs.

But in terms of the simple math, again with that 500-mile trip, which is average for most pilots, how much does speed get you? What's the difference between cruising at 138 knots, something that most Cessna 182s can do) and 174 knots, something that most mid-60's to present-day Beech Bonanzas can pull off? It doesn't take a math wizard to see the Bonanza saves 36 minutes on that trip. Is the time worth what it costs to save it? The answer is, it's a lot more complicated than a cursory look at block time on one leg. Real-world cross-country flying is all about taking all the parameters into account, and that means looking realistically at weather, optimum altitudes, passenger needs and the amount of daylight you have to work with---winter days are short. When you begin factoring in considerations such as required alternates on an IFR flight plan or thunderstorm diversions, the process can get complicated, and pilots need to have a solid grasp of all of the variables that go into planning any particular trip. So is the extra speed worth it? In the small picture, maybe not. But when you take a wider view of what cross-country flying is all about, the additional speed is priceless.

Airplanes as fast as that legendary 200 mph (which we'll think of here as 175 knots) always have the increased maintenance of retractable gear (Cirrus and Lancair excluded) and big motors, and almost always have higher acquisition costs. Within the traditional general aviation fleet, however, there are actually only a few airplanes that can honestly claim to cruise 200 mph. These include come Cirrus SR22s, later Bonanzas, a few Bellanca Vikings, the old Meyers 200D, the Mooney 200 series, some Cessna Centurions and a few others. The big question is how much time is extra speed actually saving you, and is it worth the additional expense and potential hassle?

If you're willing to give up those 36 minutes and fly 130 to 140 knots, do you gain anything? The most obvious advantage is that it costs less to get into the game to begin with. Even though the tried-and-true Skylane is probably the most expensive airplane in its category, it's still cheaper than most of the fast movers, and early square-tail Skylanes can still be found, that is, if you look hard enough and get a little lucky. But what if you desperately want the bragging rights that go with a 175 knot cruise speed? Or what if you really do need that speed on long trips? Is there such a thing as cheap speed, and how do we evaluate it?

Maybe what we should be talking about here isn't raw, dollars-be-damned speed, but miles per dollar---how much does each knot cost us (and the cost has to be defined as not only the gas being burned, but also what it costs to get into that seat in the first place). Plus, we need to apply some kind of factor for maintenance, which is going to be a pure guess. (Note: The legacy chart is in mph.)

When you start talking speeds over 140 kts, you've automatically stepped into the land of retractable gear (again, excluding Cirrus, Cessna's TTx and a number of lesser known homebuilts) and, as you move up past around 155 knots, the pickings start to get pretty slim. Let's look at some candidates and see how they stack up when you compare their stats (see "The True Costs Of Speed" chart). Be advised, however, that there's some Kentucky windage here in terms of fuel burn, and we're basing our speeds on published specs that often are questionable. Still, it gives us something that can put airplanes in positions relative to one another.

The physics behind fuel efficiency haven't changed in the last 10 years, thank goodness. In big bore singles, fuel efficiency tends to be around 11 to 12 mpg, though the smaller engine Mooneys will get you around 20 mpg. That's because Mooneys give up some cabin comfort to keep the frontal area down, plus they have worked really hard at making themselves aerodynamically efficient at higher altitudes. The net result is that they're delivering higher speeds with smaller motors (200 hp), which translates to better overall efficiency. Additionally, some of the early, small Mooneys are not as fast as the later ones, but are relatively low-priced and still deliver 145 to 155 kts on 180 horses with 9 to 10 gph fuel burns.

Another way to look at the speed is how much we have to pay for each additional mile per hour of speed when buying the airplane. Even when using Bluebook aircraft values as comparisons, which are usually low, it shows that airplanes like the Bonanza, which are much larger and more luxurious, but nowhere nearly as efficient as the Mooneys, command higher prices. Therefore, on a dollar-per-knot basis, they're much more expensive, plus they're way down in the fuel-efficiency curve. So why do people buy Bonanzas over Mooneys? Probably because they like the comfort and don't object to burning a little more gas. So, once you're going fast, other factors apparently count, as well. (Please note that the pricing figures were 2016 estimates. Times have changed, and so have prices.

Range: The Great Equalizer, Up To A Point
With all this talk of speed, there's one other factor that has to be tossed into the decision equation: range. How far will it go without making a fuel stop? When we're talking 500-mile trips, that's not usually a factor because just about everything has at least 500 nm of range, but a funny thing happens when we stretch that trip out to 1,200 miles. Suddenly, fuel capacity becomes a really big deal.

Let's say you're flying a 300 hp, 1980 Bellanca Viking that actually does deliver its advertised 175 kt cruise speed. Its spec sheet says its range is barely 600 miles (and we'll bet that isn't at 175 knots. So, to safely make 1,200 miles and still have some reserve, it would have to stop twice to get gas. The actual time in the air would be 5.9 hours (probably longer, since spec sheet range numbers usually are at economy settings, but speed is quoted at 75%). Two fuel stops, however, are going to add 1.5 hours (45 minutes per stop, which is conservative) for a total of 7.3 hours. For a trip of 1,000 miles, the Bellanca looks good again. But that second fuel stop on a really long mission is a killer.

Still, back to that hypothetical 1,200 trip. Now, let's say your lowly Cessna 182 is plodding along at 140 kts, but burning significantly less gas. More importantly, it's a newer model with 88-gallon tanks, which, according to the specifications, gives just under 800-nm of range. So, it easily can make it with only one stop. Seven and a half hours of flying, plus 0.7 of ground time, gives you 8.2 hours of total elapsed time. So, the much faster Bellanca Viking only got there 55 minutes faster. But are all of those things a really big deal on such a long trip?

Often they're not, but when it comes to multiple legs, even short ones, speed can make a huge difference. A flight of 400-nm miles won't require a fuel stop for any of these planes, but the time saved flying a much faster airplane will translate into not just one faster trip, but potentially three, or on a long, busy day, maybe four. Getting back home a couple of hours earlier, or maybe just getting back home at all instead of having to hotel it at the last stop, is worth a lot.

Now, let's toss in aftermarket auxiliary tanks so we can be flying an earlier, and much less expensive, Cessna 182 (or Cherokee 235 or!). This extra 23 gallons gives the early airplanes another 1.7 hours for a total range of about 800 miles. So, now we're flying an airplane that may have cost us as little as $50,000 (a fixer-upper, like a 1959 C-182), but we came in only 55 minutes behind the blazing Viking after a daylong trip. If you do a lot of long cross-countries, installing auxiliary tanks could be considered the best and most effective speed mod.

How about comparing the Cessna Skylane to a 300 hp A36 Bonanza? The Bonanza costs around three times more than the C-182, but the Bonanza can make the 1,200 miles with one fuel stop so it would get there 1.5 hours quicker. Okay, so after a 1,200-mile trip, the Bonanza folks will be at the gate hours sooner than the Cessna would be. The 182's cost of operation is pennies compared to the Bonanza's, especially when you factor in insurance, cost of acquisition and maintenance. You have to decide what that extra time is worth to you. Is it worth an extra $100,000 to $200,000 in acquisition and at least twice the support cost to save a couple of hours on that 1,200-mile trip you take only every other year? On the other hand, if you're routinely flying trips that long, speed is worth every penny.

Turbos Make A Difference
An aircraft equipped with a turbocharger is always going to offer increased speed and fuel efficiency over its normally aspirated counterpart because it will hold its power to a higher altitude where it gets really fast and burns less gas. The only downside to turbochargers is that they increase the maintenance and acquisition costs, and some require a bit more pilot technique.

In terms of performance, a blown A36, as an example, is supposed to cruise at 190 knots compared to a normally aspirated version at 169 knots, and a TC Saratoga will do 177 knots) versus 158 knots), while the range goes up 56 miles to a whopping 825 nautical miles. (See the "Turbocharged Speed Comparison" chart.)

It might be worth noting that while we don't normally think of any version of a Skylane as being a speed demon, the TC182RG runs right at 173 kts. Also, the TC210 Turbo Centurion series is a real sleeper at 197 knots, while the pressurized P210R is capable of running an unbelievable 212 knots at altitude. Now, that's really getting down the road!

So, What's Fast Enough?
The concept of "fast enough" is strictly subject to personal definition. For some, there is no such thing. For others, flying is its own reward, and they're more than happy to get there when they get there. For most, however, the decision involves a complex interplay between the complicated considerations of long cross-country flights, along with the pilot/owner's wants, needs and financial capabilities: In most cases we want speed, but how much do we really need it and can we afford it? In this day and age of skyrocketing prices for used planes, especially fast ones, the circle is getting harder to square, though there are still great options if you're willing to part with a bit more of your hard-earned dollars. Then again, dollars versus dream plane is an equation airplane owners have been doing since they looked at their first used plane.