Wednesday , 23 August 2017

Ownership

 

 

DB 4 ship Diamond

 

Owning and Flying the T-34 by Todd McCutchan

My current love affair with my T-34 was almost not to be. When I first began looking for a two seat aerobatic aircraft that could also go someplace in early 2009 I had already written her off for dead. While the difficulties for the aircraft from 1999 thru 2003 were well documented and publicized I had no idea that the venerable Beech T-34 Mentor was back and better than ever thanks to the dedication of a group of owners and enthusiasts known simply as the T-34 Association. They had the daunting task of figuring out how to return their beloved aircraft back to the sky and in the process forged a path that laid the ground work for all aging aircraft. Their tireless efforts created an example for many aircraft to address the issues of fatigue and aging that are beginning to become problematic for a large portion of our general aviation fleet and ensured that vintage aircraft and warbirds will be flying our skies, turning our heads, and filling our dreams for many generations to come.

History

This is not a story about those dark days though. This story is about the return to glory of an aircraft type that first flew on December 2, 1948 and has been in continuous military service somewhere since 1953. It is one of the very few military aircraft that ever resumed production after a 15 year gap and its more than 2,300 production units have served in 23 different militaries worldwide. Today there are currently 126 Beech T-34 Mentors on the FAA registry (54 A’s, 62 B’s, and 10 C’s) and an estimated 300+ total aircraft in civilian hands worldwide. The T-34 is quickly regaining its historical role as one of the most sought after and economical warbirds to own and operate.

Models and Differences

There are three basic models of the Beech T-34. They are the T-34A (civilian A-45) which was used by the Air Force and was also exported as the “T-34A / B-45” both of which are certified in the Aerobatic category, the T-34B (civilian D-45) which was used the Navy and is identified in its civilian form as the “T-34B / D-45” and is certified in the Utility category, and the T-34C which was used by NASA and the Navy and exported as the T-34C1. The C models are easily identified by its long nose and turbine engine and the few in civilian hands are certified in the “Experimental” category. This article will focus on the T-34A and B as they are the most common in civilian use. The largest difference between the “A” and the “B” airframes other than their certification class (A = Aerobatic and B = Utility) are the fuel systems (the A model feeds from either left or right while the B feeds from both tanks to a header tank), the seat/rudder pedals (the A has an adjustable seat and fixed rudder pedals while the B has a fixed seat and adjustable rudder pedals), nose gear steering (the A has it and the B is free caster), dihedral (the B has 1 degree more dihedral), the canopy emergency release system (the A releases the canopy rails and the B used a nitrogen charge to blow the canopies back), and rudder trim tab (the B has a larger rudder trim tab). There are additional small internal differences but none that are readily apparent to the pilot or make any operational differences.

Modifications

There are many modifications available for both models of the aircraft and are too numerous to list here but some of the most common are upgrading the 225 hp or 260 hp O-470 to the more powerful 285 hp IO-520 BB, 300 hp IO-550 B, or 310 hp IO-550R. The addition of 15 gallon tip tanks is also one of the common modifications to accommodate the thirstier large engines (standard fuel is 25 gallons per side) providing 80 gallons of usable fuel and a gross weight increase from 2,950 lbs to 3,200 lbs on the “A” models. Some aircraft have been modified with larger wing bladders holding 80 gallons internally and a few have external under wing tanks of an additional 26 gallons per side. Many of the aircraft have updated instruments and avionics as well as autopilots.

IMG_0439[1]

Ownership

I purchased my Beech T-34A (B-45) s/n CG-21 with the 285 hp IO-520 in June of 2009. It was one of only a handful of aircraft that met my minimum mission criteria of 2 seats, aerobatic, good cruise speed, efficient, and baggage space. I have flown the aircraft more than 300 hours since then and in that time other than complying with the AMOC’s which brought the T-34A back to its full aerobatic envelope, adding tip tanks, and bringing the instrument panel into the 21st century I have only changed the oil, 1 tire, and 1 landing light. To say the T-34 is a “gas and go” airplane is an understatement. I have flown my aircraft from NY to FL and from FL to CA numerous times and have found it to be as reliable as any general aviation aircraft I have ever flown. For flight planning purposes I use www.fltplan.com and have found their stock F-33 Bonanza profile comes very close to the actual for my aircraft. When the aircraft does need maintenance parts are not a problem. There are numerous shops around the country that specialize in the T-34 and the aircraft shares a very large percentage of parts commonality with its Beech cousins. The usual items that routinely need changing or wear out (alternators, spark plugs, oil filters, tires, brakes, hoses, etc.) are all common to the GA community. There are very few recurring AD’s on the aircraft. Every 100 hours you must lubricate your uplock rollers and check your elevator for cracks if it is still magnesium and not converted to aluminum (about 1 hour of labor total) and every 500 hours you must do an NDT check of your horizontal stabilizer for cracks (1,000 hours if you have the “heavy” horizontal stabilizer STC from Parks). The recurring inspection for your wing will depend on which AMOC you have but in general these initially occur after anywhere from 3,000 to 25,000 hours so it is not too much of a concern. Insurance is easily obtainable and will cost approximately $2,500 to $3,500 per year for an average airframe with $1 million of liability coverage.  

Flying the T-34

The preflight and startup of the T-34 is very straight forward and immediately familiar to any pilot with general aviation experience with no special equipment required save for a dzus tool or flat head screw driver to open the engine cowl doors. The difference between the T-34 and its Bonanza cousins do not really start to stand out until climbing up on the wing and rolling the canopy back. A quick step over the canopy rail to lower yourself into the roomy front cockpit and you have somehow instantly gone from flying a “military Bonanza” to an honest warbird trainer. The aircraft’s military origins quickly become apparent as the stick and throttle come readily to hand and the numerous utilitarian aspects of a true military aircraft begin to assert themselves. The aircraft start up is straight forward to anyone familiar with fuel injected engines and the throaty rumble of the Continental engine reaches your ears through the two massive “augmenter tubes” below the cowling. The augmenter tubes are there to provide both a passage for the exhaust but also to assist in drawing air through the cowling for cooling and provide the T-34 with its distinctive sound. Taxing the T-34A model is a straight forward affair through its nose gear steering and even the “B” with its free castor nose wheel is no challenge to taxi smoothly and easily. The run-up is straight forward and uncomplicated. The aircraft’s military design again comes to mind as you rotate the massive magneto switch on the forward left panel for a mag check. A few quick cycles of the prop, wipe out the cockpit to cycle the flight controls which are easy to see from you perch on top of the aircraft looking through the expansive canopy and you are ready to go flying! Takeoff in the T-34 is a very easy affair. Canopy open or closed (the canopy must be closed above 152 KIAS in the “A” while the “B” has no canopy limit), smoothly advance the throttle to the stop, add a little right rudder, and about 1,000’ later smoothly raise the nose at 55 KIAS to let the mains fly off. Best rate of climb airspeed is about 95 KIAS and the IO-520 and 550’s will yield initial climb rate in excess of 1,500 fpm but most people cruise climb the aircraft around 110 KIAS which still provides 1,000 fpm and affords better forward visibility and improved engine cooling. I tend to use the cruise climb of 110 KIAS and leave my throttle full forward and reduce the RPM to 2500’ as I pass through 400’ AGL where I also pull the mixture back to around 20 gph. On level off the aircraft accelerates rapidly to 150+ KIAS and requires left rudder trim to keep your feet on the floor. At lower altitudes (4,000 – 6,000’ MSL) the aircraft will yield a true airspeed of 162 – 167 KTAS on a fuel flow of 15 – 16 gph (75 degrees ROP). At higher altitudes (10,500 – 12,500’ MSL) the true airspeed slips to 157 – 159 KTAS but fuel burn reduces to 12 – 13 gph (75 degrees ROP). My aircraft does have GAMI injectors and I have verified that running 25 degrees LOP will save approximately 2.7 gal/hr but will cost about 9 KTAS in return. This relationship is pretty consistent at all of the altitudes I have tested it. I will include some real world examples and efficiency comparisons for number crunching geeks like me at the end but for now we’ll continue with what the aircraft actually flies like! The aircraft handles exquisitely with controls that are light without being touchy at normal speeds and stiffen up as airspeed increases towards the 219 KIAS Vne (The Vne while in the military was 243 KIAS). The controls have very good harmony and balance with no noticeable “heaviness” or “lightness” in comparison between the ailerons, elevator, and rudder. The ailerons remain effective right to the stall and the rudder remains effective throughout the stall. The aircraft provides lots of buffet as it gets close the stall and if coordinated the nose will break cleanly straight ahead. If the stall is aggravated and/or uncoordinated the T-34 will quickly drop a wing which is easily caught and brought up with the rudder. Spins in the T-34A are variable and never truly stabilize into a constant pitch attitude or rotation rate. The pitch attitude will begin to oscillate after approximately the first turn to turn and a half and the rotation rate will increase and decrease with the pitch oscillations. The entry and recovery of spins though are predictable and recovery is within a quarter turn with the applications of traditional anti-spin controls. Speed does builds quickly though on the clean airframe and care should be taken on the pullout to avoid over g and/or exceeding the Vne of 219. A 2 ½ turn spin results in the loss of approximately 1,500’ of altitude and the spin rotation rate tends to increase dramatically past the 1 turn point. No aerobatic maneuvers are approved in the T-34B (D-45) including spins. While in the military the T-34B was used for basic aerobatic training but when moved to the civilian registry they were put in the Utility category instead of the Aerobatic category.

Aerobatics in the T-34A are a joy and while the airframe is stressed to +6 / -3 g’s that reduces to +4 / -2 g’s for “rolling” maneuvers. “Rolling g” is a huge fatigue inducer as anytime you are rolling the aircraft (meaning aileron or rudder deflection) the lift being produced is asymmetrical and the ascending wing is carrying a much higher load than the descending wing. Prudent maneuvering and instruction dictates that one should always “pitch then roll” or “roll then pitch”. If your stick ends up in a corner you must respect the lowered “g” limits and this should be avoided. The roll rate is an adequate 90 degrees per second and the aircraft is very capable of doing graceful “gentleman” positive g aerobatics. A loop can be initiated as low as 120 KIAS with a 3 g pull but 150 KIAS and a 4 g pull is recommended. Immelman’s, cuban eights, hammerheads, aileron, point, and barrel rolls are all well within the repertoire of the T-34. Snap rolls are approved but not recommend due to the age of the aircraft and high torque loads imposed on the engine mounts, prop and tail section. A split S initiated at 110 KIAS and idle power will require approximately 1,500’ to complete with a 4 g pull and provide an exit speed of 165 KIAS. This aircraft is capable of performing all of its approved aerobatic maneuvers with 4 g’s or less which provides for a nice 2 g buffer below the maximum of 6 g’s. The airframe is approved for inverted flight including inverted spins however the lack of an inverted fuel and oil system preclude the execution of these maneuvers and the T-34’s airfoil and dihedral do not lend themselves to inverted flight.

Descending to the airport the aircraft does tend to pick up speed and if the air is turbulent care will need to be taken to stay below the 152 KIAS yellow arc. In smooth air the aircraft will easily accelerate to 200 KIAS in a 1,000 fpm decent with power on and is perfectly capable of exceeding its 219 KIAS Vne. Anytime the airspeed is above the 148 KIAS maneuvering speed (Va) care should be taken to ensure the g limits are not exceeded. Slowing down illustrates what is probably the weakest area of the T-34 and that is its 109 KIAS gear operation speed (Vlo). Once the gear is extended you can reaccelerate up to 165 KIAS (Vle) in the T-34A though if you ever need to get down in a hurry or keep you speed up on an approach (the T-34B does not have this provision). The T-34 is an extremely stable and predictable instrument platform and I have shot ILS approaches down to minimums on several occasions. Due to the low gear operating speed the preferred way to enter the pattern (traffic permitting) is via the overhead approach. The T-34 performs the overhead very nicely at 125 – 145 KIAS up initial to the break with a 45 to 60 degree level bank turn. This will provide 100 – 109 KIAS after 180 degrees of turn and you can extend the gear and flaps (Vfe 110 KIAS) and continue your descent from the perch to landing as you smoothly decelerate back to 90 KIAS as you roll out on final and continue to slow to a touchdown speed of approximately 75 KIAS (90 KIAS all the way with flaps up). Like its Beech cousins the T-34 lands easily and has no bad tendencies. Sliding back the canopy as you taxi in it is going to be hard to get rid of the grin that comes from flying one of the most sought after and efficient warbirds flying today.

Efficiency

So what do all of these fuel burn and cruise speed numbers actually mean? Well to put it into perspective here is real world example.

In my T-34A with tip tanks, a Victor IO-520 BB, and GAMI injectors at 6,500’ I get about 1.6 nm per gallon difference between 25 LOP and 50 ROP operation. This is the only real number that matters as it is the one that actually impacts your pocketbook; nm/gal.

12.0 nm/gal 25 LOP and 10.4 nm/gal 50 ROP (this of course was pushing a 6 knot headwind). No wind efficiency would be better at 12.4 nm/gal at 25 LOP and 10.8 nm/gal for the 50 ROP (mathematically derived).

There is also a 9 KTAS difference (164 vs. 155) and 2.7 gal/hr (12.5 vs. 15.2).

If you assign an arbitrary fuel cost average of $5 per gallon and budget reserves for labor, parts, engine, prop, and an additional miscellaneous reserve you get a “dry” direct operating cost for the engine/airframe of $71.94 (this is a best “guestimate” and will vary depending on operator/aircraft). Most likely I am conservative on my reserves which translates into “high”. Better to be pleasantly surprised though in my thinking when the mx or overhaul bill comes!

Beech T-34 Direct Operating Cost (D.O.C.)

Fuel (avg)

$5.00

$75.00

Maintenance Cost

Labor/Hr

$65

$32.50

Parts

$7.50

Engine Reserve

$22.35

Propeller Reserve

$4.58

Misc. Expenses

$5.00

TOTAL HOURLY D.O.C.

$146.94

 

Over 150 nm enroute flight the difference would be:

150 nm

25 LOP

50 ROP

Flight time (hrs:min)

0:58

0:55

Fuel Burn (gallons used)

12.1

13.9

Fuel Cost at $5 per gallon

$60.50

$69.50

Airframe Cost ($71.94 per hr)

$69.54

$65.94

Total Cost

$130.04

$135.44

 

Over a 450 nm enroute flight the difference would be:

450 nm

25 LOP

50 ROP

Flight time (hrs:min)

2:54

2:44

Fuel Burn (gallons used)

36.3

41.7

Fuel Cost at $5 per gallon

$181.50

208.50

Airframe Cost ($71.94 per hr)

$208.63

$196.64

Total Cost

$390.13

$405.14

 

I will let everyone interpret the above for themselves and come to their own conclusions. One thing that stands out to me though is just how efficient our airplanes really are! 12.4 nm/gal = 14.3 sm/gal and when you translate this into traveling a straight line distance vs. following curvy roads you can generally add another 15 – 25% more!

As an example here is a trip I flew between Fort Wayne, IN (SMD) and Kentucky Lake (M34) on May 11, 2011. For comparison purposes I have made both the flight and drive from airport to airport and used statute miles and still air. I did not include airframe cost as I am not sure how to compare that to car depreciation and maintenance cost.

 

 

Mazda CX-7
(18 mpg)

T-34 25 LOP
(14.3 mpg)

Difference

Statute Miles

435

331

104 miles less

Time

6:54

2:08 (still air)

4:46 less

Fuel Burned
(Gallons)

24.17

23.15

1.02 gallons less

Fuel Cost
($4.25 car)
(4.75 plane)

$102.71

$109.95

$7.24 more

Fun

0

100

100 times better!

 

The T-34 is the most efficient cross country aircraft in its category with the possible exception of the SF-260B. The graph below is compiled from actual operators and “typical” cruise settings. They do not necessarily represent the most efficient nor are they all comparable (i.e. 75% power) but are real world operators feedback at mid-altitudes for these aircraft (4,000’ – 6,000’ MSL)

 

T-34 (285 hp)

CJ-6 (285 hp)

Yak-52

T-6

T-28A

T-28 B/C/D/F

SF-260B

SF-260C

KTAS

165

140

120

135

150

200

175

165

Fuel (gph)

15

15

15

30

35

50

15

15

NM / Gal

11.0

9.3

8.0

4.5

4.3

4

11.6

11