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When Hollywood Ruled The Skies - Volumes 1 through 4 by Bruce Oriss


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PostPosted: Tue Nov 24, 2009 7:46 am 
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Bill G, the other thread got buried so here's my two cents on the T-37 as you requested... 8)

The T-37 "Tweet" primary jet trainer is...well...a Cessna. Given the purpose for which it was built, to provide novice aviation cadets and young officers primary jet training, Cessna's little jet was ideally suited and it shares many of the same docile, forgiving characteristics of the prop-driven Cessnas many of us have flown. Prior to getting my civilian type rating in the T-37 earlier this summer, I flew it in the early '90s as a primary student in USAF pilot training for six months, 100 flying hours and a handful of simulator sessions. I learned contact (pattern work, spins, stalls, acro), instruments, formation, and IFR (cross-countries) navigation and VFR (low-level dead reckoning) navigation.

The aircraft weighs around 6500 lbs fully loaded with fuel and two pilots, with 2000 lbs thrust total in the Continental J69 turbojets (a built-under-license version of the French Turbomeca Marbore II). On an FAA standard day, rotate at 90 knots and nosewheel off by 100 kts, gear up with a positive rate of climb, flaps retracted at 110 kts, cruise climb at 180 kts below 10,000 feet and 160 kts above 10,000 feet. Rate of climb is initially near 2000 fpm in my friends' Tweet but the engines on this jet seem to outperform the USAF jets I flew. Best glide and max endurance speed is 125 kts with glide ratio of 11 nm/5000 feet. Flying a local low altitude sortie, approx 88% rpm gives you 200 kts and 180 gal/hr fuel burn straight and level. Cross country max altitude is 25,000 feet due to physiological considerations in play with no pressurization system. At 24,000-25,000' cruise altitude figure 260 kts true airspeed and 300 nm range no-wind. It only carries 321 gallons of fuel in the wings and fuselage. The USAF instructors always told us the Tweet had the fastest G onset of any aircraft in the Air Force inventory. I never researched to confirm whether this was really true but to be sure they were rightly trying to impress upon us newby jet students the importance of textbook execution of the anti-G straining maneuver since we were new to pulling G's and wore no G-suit. Anyway, max limiting structural airspeed is 382 KIAS or .70 mach. For a loop, cuban 8, Immelman, enter at 250 kts and military (max) power, 4 Gs, over the top at 120-130 kts, figuring on using 2500 feet of altitude to complete the maneuver. Enter aileron rolls and barrell rolls at 220 kts 90% rpm, chandelle and cloverleaf at 220 kts and military power. It's flight controls are wonderfully balanced and it's very responsive (a little more than 360 degrees roll per second). True to Cessna form, it's stall characteristics are benign and any wing drop easily countered. It was designed to spin and recover easily from a spin. Figure 3 seconds and 500' loss per rotation once established in the spin. Opposite rudder and stick forward to break the stall and you recover from the spin every time. I like to compare the jet's handling characteristics to a little sports car, say an MG convertible...not very powerful, but very maneuverable, crisp and rapid responsiveness and a natural aerobatic airplane. Fly up initial for the overhead break at 200 kts, break with idle power and extend speedbrake, then gear and flaps on-speed, final turn (base) at 120 kts, final at 110, over the fence at 100 kts with the airplane weighing around 5000 lbs. No reason you can't get it stopped in 3000' as long as you were on a 3 degree glidepath and on speed. Max crosswind component is 17.5 kts for dry runway, 13 kts for wet runway--no antiskid system on the wheel brakes. The USAF's training command mandated a minimum runway of 5000' which was pretty conservative. As long as you're on speed and the runway's dry and free of ice/snow, 4000' leaves plenty of margin and you could probably pare that down to 3500' so long as weather and density altitude (temp and field elevation low) were favorable, 3000' being bare bones but why hang it out there so to speak, and tempt fate... I can take the T-33 in and out of a 4000' runway so long as conditions are favorable and I nail the speeds and touch down in the first 700' or so, but that's bare bones and I wouldn't want to base out of an airport where that was the longest runway. 5000' is a comfy everyday T-33 runway length for me. T-33 threshold speed is 115 kts but it weighs around 11,000 lbs at min fuel landing weights...lotsa energy and no antiskid system. Remember that Kinetic Energy = 1/2 Mass x Velocity squared so if you're a few kts hot, it rrreally increases your kinetic energy and stopping distance, even on the relatively lightweight T-37. Man, DO NOT be even a few knots fast in these jets or you float float float...If memory serves (Mustang pilots chime in here if I'm wrong) my Mustang buddy comes down final at 120, short final at 110 kts and can get it in and out of a 3000' runway just fine, but he's got a couple thousand hours of Mustang time and stays very current and proficient, is a naturally good stick so the answer to the min runway does depend on pilot ability, experience and personal comfort level. You're right about the offensive nature of the engine noise but I'm warped and like jet noise so I think it's cool...anyway, better wear earplugs and the best insulated helmet earphones Oregon Aero sells. Taxiing with the canopy open is deafening if you don't have proper ear protection and headphones. Speaking of taxiing, the Tweet has hydraulic nosewheel steering activated by pushing a button near the bottom of the stick, then using rudder pedals to steer the nosewheel. I should've mentioned earlier rudder becomes effective around 65 kts so nosewheel steering is required on takeoff til you're up to that speed. I hope this filled you in on the Tweet Bill. I'd love to hit the slopes this winter in Snowmass!!


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PostPosted: Thu Nov 26, 2009 12:51 am 
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Joined: Thu Sep 02, 2004 6:19 pm
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Location: pewaukee, WI ,usa
Awesome post Paul.. great info... nicely done...
Then again, I guess I'm a little biased.. :-). Happy Thanksgiving!

hh

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