450 Stearman Pages

The 450Logbook

Resources for
The 450 HP Stearman

These pages are all about flying the Boeing Stearman Model 75 fitted with the famous Pratt & Whitney Wasp Jr., R-985 450 horsepower engine.

First Flight in 26 Years:

Prior to this restoration, the last flight of this airplane was in February of 1978. She was involved in an accident in that year which 'totalled' the aircraft, the first step in my eventual ownership.
Since she was born in the 40's, no one owner had owned this aircraft as long as it took me to make her airworthy again. After lots of runups, taxi tests, final tweaks, and years of restoration, she flew once again after almost 30 years hiatus, on the fourth of July, 2004. At the controls with me in the aircraft was Kevin Munson, an experienced Stearman pilot who gracefully consented to the task.
Review the History Page and you'll see that this is a new airplane for the third, or perhaps fourth time in its life!
This is the bird that dusted countless fields all over California, and served well and faithfully for many decades.
She's still loud, smelly, shakes a lot, incredibly powerful, and an absolute joy to fly.

First Flight for This airplane:

N7740C flew for the first time (again) on the Fourth of July, 2004 (how appropriate). On an overcast day at Half Moon Bay Airport, she lifted straight, clean and easy. These crow-hops showed that some adjustments were needed in the elevator trim, and some rubber channel on the upper wing gap seals was re-glued in place.
Within the first hour of flight, a problem with excessive oil porting out the engine was found. It turned out to be a poorly routed crankcase breather.
In the first 3 hours, I added friction to the prop control, sealed a gap in the forward left inspection door, replaced the rebuilt spark plugs with new plugs, and added some insulation on the inner firewall to keep the forward cockpit cooler. No other adjustments were necessary. For such an extensive rebuild, these issues were nothing.
Apparently I got the rigging right as she flies straight and level when trimmed. There is no tendency to wander nor roll of course.
The brakes are excellent in feel and power, and the tailwheel steering is positive and very controllable.
At cruise power settings on warm days, the engine maintains about 180 degrees F oil temperature, and the cylinder head temp is good too, so the cowling, oil cooler, and various cooling outlets seem to work well.
In summary, I'd say there were no serious squawks after the restoration, and all the design decisions seem to be working out ok. She flies straight, true, and completely controllable in all axes. It's a very nice airplane!

Flying Characteristics:

Generally:
This 450 Stearman is a solid, stable, and well- mannered airplane in the air. The controls are smooth and predictable, and stick forces are about the same as other general aviation aircraft. Actually, control forces are very light considering a gross weight of 3200 pounds. It stalls gently. It is however, an airplane that can bite. It has a power to weight ratio of about 7 pounds for each horsepower. This ratio is comparable to a P-51 or Corsair. Even at gross weight, it is a real exhilerating ride, and with just one aboard, the power and responsiveness is tremendously entertaining.
Some points to consider:
- It is a large and heavy airplane compared to most 2-place airplanes. In the air, the two sets of wings and the big front end make for a wholly different experience whem compared to more common aircraft.
- It's heaviness and solidity can be felt when the power is reduced to idle. Even at idle speed, the momentum of the large propellor can be felt, and must be accounted for. Other airplanes noticably float and flutter when gliding, where the 450 does not. Power-off, it glides like a brick.
- Even more so than the standard Stearman, visibility over the nose is practically nonexistant.
- This is no longer a good training aircraft. With 220 horsepower, it was a great trainer. Now it is not.
- Take off can be accomplished easily with 2/3 power. Climbout is typically 85 mph and about 1,000 FPM. Cruise settings of about 120 mph burning about 20 GPH and an economy cruise setting of 100 mph and 15 GPH are common. Stall speeds are about 50 mph without power, and final approach is generally 75 MPH for 3-point landings, and around 80 for wheel landings. Technique and familiarity are necessary to deal with the lack of forward visibility on final approach. - Open cockpit flying is VERY different. It's a lot like riding a motorcycle at 125 mph, several thousand feet above the ground.
- Because it is a taildragger, has a low wing, has a somewhat narrow gear, a long fuselage, huge torque and P-factor, nonexistant forward visibility in the 3-point attitude, and lots of power, an experienced pilot must pay attention 100% of the time, and have current and appropriate piloting skills and reflexes.

Compared to Stock Stearman:
At engine startup, the 450 sounds different from the Stock Kaydet. The engine has a different rumble due to being a 9 cylinder as opposed to the stock 7.
The addition of a controllable propeller adds another step to the startup sequence as the pilot monitors the oil pressure and moves the prop control to fine pitch at the appropriate time.
Taxiing, the 450 is different. A stock Stearman has better visibility over the nose, but both require S-turns. The 450 has considerably more thrust at all power settings and leaves the parking spot with much less power application. Brake usage and application while taxiing is the same in either airplane.
During runup, I seldom if ever reach climb-power, much less full power as one would with a stock motor. Climb power of 30 inches is just too much strain on the brakes and everything else in my opinion just to exercise the prop and magnetos. I feel a safe runup reaches at least 1500 RPM, which is sufficient to kick in the prop governor and to check the magnetos. In the stock airplane, much more power can be used without threatening to pull the airplane nose-over.
Takeoff in the stock airplane is leisurely and slow compared to the 450. In the 450 power must be fed in slowly to prevent the radial from coughing (as with the Continental too) but more so to prevent a wild excursion to the left as the torque of the more massive prop becomes apparent.
Just as the pilot is getting the airplane straightened out from the P-factor of the 450/prop combination, the tail must be lightened as the airplane begins to climb within just a few hundred feet, well before full power is applied.
At about 2/3rds power and 350 feet of runway, the 450 is off the ground at the same speed as the stock airplane, but a good 300 feet sooner. One hundred feet later, when full power is applied, the airplane has climbed about 20 feet and is accelerating through 70 to 80 mph.
If held at a best-angle speed of about 65 mph, the 450 Stearman will be very nose-high, and be climbing at over 1,500 feet per minute. Held at a more leisurely 80 mph and 30 inches of power, the 450 makes about 1,000 fpm climb. At gross weight the standard Stearman will produce easily 650+ fpm climb with full power.
Once in the air, the 450 and the Kaydet fly about the same. They both stall at similar speeds, and all control forces are similar. However, where the typical Kaydet cruises at about 95mph while burning around 11-13 gph, the 450 typical cruise will be at 115 mph while burning about 13-15 gph, showing 26 inches of manifold pressure. The 450 can cruise all day at 27 inches while showing about 120 mph, and will drink a bit less than 20 gph at that speed. Slowing to stock Kaydet speed will actually show a fuel burn aroun 10-11 gph, just a little less than the Continental.
Slow flight characteristics are the same in either airplane. In landing configuration however, the size of the prop and larger engine produce a bit more drag. I believe this results in an increased sink rate when speed slows below 65 mph. Becuase of this, a touch of power before flaring is helpful in the 450 Stearman.
A touch-and-go landing in the 450 shows the greater torque characteristics of the larger 450 prop over the stock airplane. While rolling out, re-application of power for the liftoff must be handled gently.

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