Light-Light Twins
In your article about light-light twins in the June issue, your chart didnt contain the most important element: Single-engine climb rate.
You mentioned Pipers book value of 240 FPM for the Piper Apache.Was that for the Apache 150 ?I know they also built the Piper Apache 160 and a 235 that became the Aztec. What about the other twins, Travel Air, Dutchess, Comanche and Cougar?
Because all the engines of the light twins have 2000-hour TBOs, a single-engine rate-of-climb comparison would be more meaningful to your readers.
Egon Grothe
Brookfield, Wisconsin
Youre right, we should have provided more information on single-engine climb rates. It was omitted for two reasons: One was space, the other our skepticism about how much meaning these performance figures have. With a large grain of salt, here are the published single-engine climb rates, at gross weight. (The Apache is the 150 HP version.)
Piper Apache: 240 FPM
Beechcraft Travel Air: 205 FPM
Piper Comanche: 260 FPM
Piper Seminole: 212 FPM
Beechcraft Duchess: 235 FPM
Grumman Cougar: 200 FPM
The real-world difference between the Comanches 260 FPM and the Cougars 200 FPM is meaningless, in our view. A single-engine climb rate between 0 and 150 FPM for any light-light twin is more realistic.
I usually don’t write to magazines, but I had to set the record straight on the Apache.Author Durden apparently has his reasons for not including the Apache 235 in his commentary on the Apache. While I would agree with him that the original Apache was underpowered, the PA-23-235 has decent power. I realize that only 117 were built from 1960 to 1966. The Apache did not go out of production in 1961, as mine is a 1963. There’s still one 1966 registered. Only 52 are registered today.
My 235 will carry full fuel plus 1000 pounds or five FAA types plus more baggage than can be fitted in the cabin. I cruise at 160 knots TAS on 24 GPH, depending on altitude.As for single-engine performance, the more under gross, the better it is. I usually fly solo but have had three people plus full fuel and can get 200 to 250 FPM at 5000 feet.
I have also found that the book numbers are close, although the next item on my wish list is a Shadin fuel computer so Ill be able to tell more exactly how close the book is. All in all the Apache 235 is a great airplane but the Aztec certainly has more room for everything.
Jim Kennedy
Via e-mail
Mo vs. Bo
You really stacked the deck against the Mooney in your article entitled Mo vs. BO in the December 1999 issue. The straight-tailed F33 Bonanza does indeed have a reputation for being a great airplane. Unfortunately Ive never flown one. But Ive owned and flown a variety of Mooneys for nearly 20 years so I can speak with some authority about them.
Contrary to your denial-and limiting the statement to production singles-they are the fastest airplanes on the lot faster even than many twins. The turbocharged Mooney M20M Bravo, powered by a Lycoming 270 HP TIO-540-AF1B with a maximum cruise of 195 knots at 13,000 feet can run away from the F33 and hide.
At 25,000 feet, the Bravos maximum cruise of 220 knots is 20 knots faster than the new turbocharged B36TC Bonanza. At 75 percent power, the B36TC will cruise at 200 knots, powered by a 300 HP Continental TSIO-520-UB.
In your article, you compared the Mooney 201 with the F33 Bonanza. The M20J 201 is the slowest of the Mooneys which followed the Roy LoPresti clean-ups. Even with this disparity in horsepower between the two, the M20Js Ive flown true out at 160 to 165 knots at 75 percent power, the same speed you claim for the F33 Bonanza. If you don’t get this much from your 201, youve got a lemon.
Yes, I noted that the Mooney airspeed you quoted was for 65 percent power, but you failed to mention the Bonanza power setting. It would have been much fairer if you had compared the Bonanza to the Mooney Ovation, which is powered by a normally-aspirated Continental IO-550-G rated at 280 HP.Regarding handling: Ive flown some 30 aircraft makes and models and I find Mooney handling to be delightful because its so precise.
This is due to the use of push-rods instead of cables. Cables often go slack, giving rise to control hysteresis. Most high-performance sailplanes also use push-rods to avoid control surface flutter and hysteresis. The claim that the Mooneys are heavy in roll is exaggerated. Before I started flying Mooneys, I had been flying Piper Arrows (straight and taper wing), and, in the transition, I never noticed any great difference in control force required for a comparable roll rate. My petite wife has no problem rolling our Mooney M20K quickly into and out of a turn.
With regard to cabin width, your implication that the Bonanzas 42 1/2 inch cabin width versus the Mooneys 41 1/2 cabin width is a significant difference is an exaggeration. Do you really believe that 1/2-inch less room per person is worth mentioning?
Finally, the accidents sidebar gives an incomplete picture by failing to note the total number of accidents for each make in the short period of time between 1996 and 1998. The percentage of in-flight break-ups for Mooneys is listed as 2 percent. Since there is no such thing as a fractional accident, this means that there could have been one in-flight break-up out of 50 accidents or two break-ups out of 100 accidents during this period.
So the 2 percent rate for the Mooney versus the 1.7 percent rate for Bonanza doesnt tell you anything about the actual number of accidents in each case. Mooney in-flight break-ups are virtually unheard of. You can count the total number of such accidents on the fingers of, at most, both hands. On the other hand, the tail-flutter damage category you list for Bonanza accidents is surprising because this problem persists despite the V-tail cuff modification.
Melvin G. Whybra
CFII
As we noted in the article, the basis of comparison was aircraft that were competitors when new. We suspect buyers select aircraft according to price, number of seats, speed and payload, although not in that order. Few do a line-by-line comparison of horsepower and engine type.
As for speed, again, we limited our comparison to these two models, not the B36TC nor the Bravo and Ovation. There’s no question that the F33 is faster and will walk away from the Mooney 201 at equivalent power settings. Fly them off and you’ll see.
As we see it, your 201 speed claims are pipe dreams. Weve flown many 201s and find the speeds in the 155 to 160-knot range for normal cruise settings. When an owner claims 165 knots for a stock model, we suspect wishful thinking or inaccurate instrumentation.
In our experience, few pilots would prefer the Mooneys handling over the Bonanza, even if they might prefer the Mooney for other reasons, mainly related to cost. Other than the Cirrus, we have not encountered a light airplane whose controls are as we’ll harmonized as a Bo.
As noted in the sidebar and a subsequent article in the January 2000 issue, V-tail flutter incidents have been limited to early model Bonanzas. The cuff mod isn’t an issue here.
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New Brighton, Minnesota
