FLYING THE T-33 - THE BEST SELLING JET TRAINER! (CONTINUED)
Ready To Start
Because of the different engines in the American and Canadian versions of the aircraft the starting procedure varies slightly between the two. However, they are both old-jet engine technology and involve switching things on or putting the fuel in as the rpm builds - very different from the automatic starting of modern jet engines.
As the American version, fitted with the Allison engine, is the most prolific its starting procedure is described here. It is also the most critical of the two different engine types during starting. When starting the Allison it is very important to ensure that the aircraft is pointing into wind. This is because the engine is more likely to have a hot start if there is any tailwind up the jet pipe. Then once the preliminary checks have been completed (and the fuel counters have been set!) the fuselage booster pump is selected on, followed by the selection of the start switch. As the starting process begins the driving parameter is rpm, which dictates when all other actions are performed. At 9 per cent the ignition is put on, followed by the starting fuel at 9.5 per cent. The throttle is moved very carefully, while watching the JPT (jet pipe temperature) to ensure it stays within limits, to the idle position as the rpm reaches 26 per cent; the start fuel is then selected off. After start the checks are very simple, involving switching the avionics on and checking the emergency fuel system (a by-pass capability should the main fuel control fail).
Taxying - Man Or Mouse! (back to top)
On most jet aircraft once you have got the aircraft started the hard work is over until you are lined up ready for take-off - not so on the T-Bird!! Indeed, if you can taxy the aircraft successfully, there is no need to get airborne - because nothing else that you do in the aircraft will make you concentrate so hard!! It is very difficult to get to grips with and requires a lot of confidence and positive control. The main problem is that it is easy to get the nose-wheel stuck off to one side when manoeuvring at low speeds. If this is done the only option might be to shut down, get out, and kick the wheel straight and try again. - not cool at all! The best technique seems to be to keep the power on and taxy at slightly higher than normal speeds.
Getting Airborne (back to top)
If you manage to get to the holding position ready for take-off, half the battle is over. Its now time to perform the pre-take-off checks: Fuel booster pumps on, flaps 30 per cent (US T-33), airbrake in, trims set and most importantly canopy closed and locked.
When at low rpm the throttle must be moved very gently to prevent the JPT from rising above limits; this is of particular importance on the take-off roll. I tend to set about 65-70 per cent before releasing the brakes, it is then less of a problem moving the throttle to full power. In order not to slow the acceleration too much it is advised that no back pressure be applied to the stick until close to the rotate speed of 80-90 knots (92-103 mph). The aircraft will then gently lift off at about 110 knots (125 mph). The thing that strikes you instantly, on your first few take-offs, is how sensitive it is in roll. However, you tend to settle quickly within a few minutes. Once airborne the gear is selected up, followed by the flaps above 140 knots (160 mph). The best climb speed is 275 knots (315 mph) at the lower levels, with the power set at 98 per cent rpm and less than 655 degrees on the JPT.
General Flying Qualities (back to top)
Both the Lockheed and Canadian versions of the T-Bird are a delight to fly. They are very simple and their flying qualities are very honest with few vices. However, there is one unusual characteristic that could catch you out if you were unaware of the problem: the aircraft must not be side-slipped above 130 knots (150 mph). This is because a potential loss of control could be experienced due to the tail fin stalling at high side-slip angles. (Side slip is angle of attack for the fin, which can stall in the same way as the wing does.) This could completely ruin your day if it happens at high speed or close to the ground! The problem does mean that care needs to be taken when de-crabbing during a crosswind landing.
During normal flying the side-slip problem is not an issue and the aircraft is a pure delight to manoeuvre around the skies. During harsh manoeuvring it 'talks' to you with light and then medium buffet signalling that you are flying at the maximum capability the aircraft can give you. At no time do you feel as if the 'cliff-edge' might be just around the corner.
Slow Speed And Aerobatics (back to top)
The aircraft has a very gentle and benign stall in all configurations. With the gear and landing flaps down it stalls at approximately 89 knots (102 mph), while clean the speed of the stall is increased to 100 knots (115 mph).
Because the aircraft 'talks' to you so well when you are aggressively manoeuvring, very tight aerobatics can be performed. The 'book' recommended figure for a loop is 350 knots (400 mph) and for a barrel roll is 300 knots (345 mph). However, with experience it is possible to reduce these speeds slightly. The aircraft also has a very tight turning capability and appears to be able to turn around its own wingtip. These aerobatic qualities make the aircraft ideal for display flying. They allow the whole show to be very tight, at relatively low speed (therefore low 'g'), keeping all the excitement in front of the crowd.
Very Low Drag (back to top)
During general flying you get the impression that the aircraft is very 'slippery'. Even Tony LeVier's first flight comments about the aircraft - "It not only flies better than the single-seater, its faster!" - hints at the low drag nature of the T-Bird. This quality has mostly good points with the odd unusual one. It gives the aircraft a healthy top speed of 505 knots (580 mph) and improves range and fuel consumption. It also allows a great display opening manoeuvre by diving to 500 knots, levelling off at display height (100 feet) and closing the throttle before you pass the crowd. Because of the low drag the aircraft slows very little by the time the crowd are passed and it appears that this silent aircraft is whooshing by!
On the unusual side of low drag is the engine-out behaviour of the aircraft. This can really catch you out during practice forced landings if not reasonably experienced. Most jet aircraft have the gliding capability of a brick, making height the most important factor because it can always be lost by diving the aircraft with little increase in speed. Even with the gear down this is not true in the T-Bird and it just goes on and on gliding (glide ratio 2½-3 to 1), making an overshoot of the runway a possibility - not good if the engine has failed. The problem is worsened by the fact that the best glide speed is 165 knots (190 mph), which is reduced to 115 knots (132 mph) for touchdown. In such a 'slippery' aircraft it's no wonder the touchdown is difficult to judge, while trying to loose 50 knots (57 mph). The forced landing is definitely something that needs careful training during conversion onto the aircraft, and frequent practice thereafter.
Back In For Landing (back to top)
Coming back to the circuit (usually with a big smile), the aircraft is very docile and easy to fly (as long as you do not de-crab above 130 knots (150 mph) from a crosswind!). Normally, the gear and the first stage of flap are lowered downwind and speed stabilized at about 160-170 knots (184-195 mph), using 65 per cent rpm. Turning finals, full flap is lowered, and the speed reduced to 140 knots (160 mph). The speed stability of the aircraft is very good round finals (typical straight wing aircraft) with very little throttle movement required after the initial power reduction. Once on finals the speed is reduced to 115 knots (132 mph), while ensuring the power stays above 45 per cent rpm. To help in this the speedbrake is selected out. This requirement to keep the rpm above a certain minimum is typical of old-jet engine aircraft, where the time taken for the engine to spool up in the advent of a go-around would be too long. The speed over the 'hedge' is 105 knots (120 mph), touching down at about 95 knots (125 mph).
One aspect of the landing which, as far as I know, is unique to the T-Bird is that the canopy can be opened on the landing run to act as a drag device, shortening the landing distance. In an emergency the canopy can be opened immediately on touchdown; however, even for normal operations it can be opened by up to two inches below 90 knots (103 mph), and fully opened at taxy speed! - You certainly get a blast of air through the cockpit when the canopy is opened two inches at 90 knots!
With the excitement of the landing over the taxy back is next! However, with this mastered the shutdown is simple. Once all the noise has stopped you still have one job to do - get out as quickly as possible and put a fuel catcher pan under the aircraft, it tends to deposit quite an amount on the floor otherwise, making you very unpopular with the airport authorities!
LASTING IMPRESSIONS (back to top)
When the flying is over you can understand why the T-Bird was so popular with all that have flown it. The aircraft really is a delight to fly, with almost viceless handling. As a display aircraft it is close to ideal, having the feel of a baby Hunter - quick, very manoeuvrable, producing a tight compact display that can thrill the crowd, without flying the aircraft to its limits.
The T-Bird is an excellent civilian owned vintage jet; it is not too expensive to buy and maintain and is relatively easy to fly! In the States they are very popular but over here they are rare. It would be good to see more of this American 'classic' on the British display circuit - hopefully, I may even get the chance to take one airborne again!
My thanks to those T-Bird owners who have let me share the rare treat of flying their American 'classic'.
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