PUBLISHED: 16:01 15 August 2012 | UPDATED: 14:19 10 October 2012
Thanks to one owner's determination to build Britain's first 'big engine' Titan Mustang, the fine-handling kitplane finally shows get-up-and-go to match its good looks.
Words Clive Davidson Images Keith Wilson
Long before I met aircraft builder Ben Chester-Master and saw a Titan T-51 in the flesh, I had no reason to give the aircraft very much consideration. The Titan design emanates from a 75% scale replica first designed and flown with a 100hp Rotax engine. The tiny and totally under-scale prop didn’t really appeal, and I was highly dubious of the claimed performance. Compared with the absolutely gorgeous Stewart Mustang, a faithful all-metal scale replica with a 500hp Chevy V8, and the ‘plastic fantastic’ 650hp Thunder Mustang, I really thought the Titan was a lightweight exercise riding on the name of Mustang.
However, the P-51 has a huge following, not just in the States but world-wide, and Titan’s is the only current kit out there for those in the market for an affordable replica. The T-51 obviously fills a gap and there are an increasing number of them about. They are selling well and I had to concede there must be something about even the Rotax-engine Titan: it couldn’t all be hype.
I have to declare now that as soon as I became involved alongside Dan Griffiths in the test programme of Ben’s aircraft, G-TSIM and began to learn more of the actual project and its owner, I came to see the aircraft in a whole new, positive light. Here was an airframe fitted with an engine of far more promise: a 183hp Suzuki V6 driving an impressive 84 inch diameter Whirlwind Aviation 100-4 propeller through a reduction gearbox. In pushing back the boundaries by becoming the first UK builder to put the converted car engine into this airframe, Ben has had an epic struggle (see ‘The builder’s perspective’, p.31). I am impressed that he has succeeded in doing this within the Light Aircraft Association’s amateur construction/Permit to Fly framework. The fact that the up-engining job has been done elsewhere in the world most assuredly does not give anybody carte blanche to do the same thing here.
Among other things, the LAA demands full and accurate supporting paperwork. For G-TSIM, a maxium all-up test weight of 1,600lb (726kg) has been allowed, with the unfortunate effect that the second, dual-control seat cannot be used for the foreseeable future. Vne was reduced from the published factory figure, there was no clearance for aerobatics (quite standard for the test phase) and spinning was not allowed.
The LAA stipulates a minimum of five hours test flying for a newly-constructed amateur-built aircraft. In this case, the combined test flying amounted to 16 hours and the only real issues were high coolant temperature and a propensity to fly left-wing low. The first was solved with extra cooling slots in the cowling and the second with a realignment of the left flap.One thing that was apparent right from the start was that the T-51’s basic handling is delightful.
Nevertheless, for all the 400 hours he had logged in his Slepcev Storch, before he took his turn at the T-51’s controls Ben put some time in on a Globe Swift. This gave him some experience of a retractable undercarriage and constant-speed propeller. Topping this up with stick-time on fellow Storch owner Peter Holloway’s Miles Magister, all that held him up was an improvement in the weather after the demise of this Spring’s hosepipe ban...
So let’s go fly the thing
I have seen P-51 pilots approach their aircraft from the front of the left wing, climb onto the left tyre, the wing leading edge and onto the walkway before swinging a leg into the cockpit. With the Titan it is more normal to approach from behind the wing and place a foot on the walkway and haul oneself up into the cockpit with one hand on the canopy rail. The wing sits at quite an angle and I can say from experience that this is best not done with a handful of a navigational charts, glasses, flying gloves, goggles, headset and the rest.
Stand on the squab and slip down into the seat, supporting your weight with the sides of the cockpit and canopy rails. Park the leather helmet on the stick. Before strapping in, just take a look outside − the all-round view is just as you might expect from a fighter. Of course the long nose blanks out the view directly ahead, but this as it should be with a Mustang and is something you soon work around.
Find the four straps and buckle up. There is no seat adjustment. Ben is 6’ 2”, I am 6’ and Dan… well, he asked for a cushion. The position and throw of the stick are comfortable and nothing is likely to snag or restrict its movement. The control column has a ‘coolie’s hat’ on the top to trim in both pitch and roll. The radio press to transmit is positioned where the full-size P-51’s gun trigger would be.
There is no parking brake, which is no problem so long as the toe brakes are covered when starting. The microphone and earpiece leads from the helmet plug in on the right fuselage wall, by one’s elbow − best connect these up before strapping in.
By the right knee is the single fuel selector and note that both tanks drain when either left tank or right tank is selected. The red-painted filler caps can be visually checked for security from the pilot’s seat. The tanks hold a combined 85 litres and their indicators are set in the wing roots, left and right, right where your hands would dangle if you allowed them to drop to your sides. They are a little awkward to read, so it is best if you take more than a squint now to view the green and red arcs. As with all fuel indicators, take the readings with a pinch of salt: simply plan on around 30 litres per hour fuel burn and you won’t be too far wrong. (When refuelling it is wise to pause when either of the interconnected tanks appears to be full, topping up as the level reaches equilibrium.)
The belly radiator cooling flap control lever is mounted on the left-hand fuselage wall in an easy to reach position − but other than to check its function on the ground, I always left it open in flight. There’s a cockpit cooling vent selector forward of this, something we’ve left closed in this year’s Spring weather.
The undercarriage selector is well positioned and works without any fuss or much delay. When airborne the lever is released from the detent, at which point it will start to move in the right direction of its own accord, only light pressure being needed to shift it all the way to the wheels-up position. Gear down is indicated by a triangle of green lights, sensibly positioned to the top left of the instrument panel. A red light warns when the gear is not down and locked. A loud, modulating warning blares when low power is selected without the gear being down and secure. The emergency undercarriage lever is on the lower left. The circuit-breakers are all mounted on a central panel, alongside the master switch, starter and selection lever for the electrically-operated flaps.
Looking out of the cockpit, the flap selection graduations can be seen as the flaps slide down: Use 0 for cruise, 1 for takeoff, 2 for dogfighting (you are slipping back to 1944/45 now, Clive − Ed) and steep turns below the 100mph white-line speed, and 3 for a standard landing. That leaves 4, and we will come to that later.
The throttle, prop and dummy mixture lever are sited in the standard fighter position on the left fuselage wall, just where the left hand naturally rests. There are two separate ‘ignition switches’ (actually bus bars for the Simple Digital System or SDS − but for the moment regard them as mag switches). Mixture is regulated by means of a rheostat − a rotating knob to you and me − sited just under the glareshield. The white index line is positioned at five o’clock for a cold start: once the engine is running, the mixture is leaned almost immediately to the standard four o’clock position, where it can generally be left for flight. Starting with a warm engine, the four o’clock position works very effectively.
The two electric fuel pumps are mounted next to the CBs, as is the electric primer/fuel boost pump. When testing the secondary ignition system on the ground, the engine revs do ‘blip’ momentarily. This is slightly more heart-stopping when in flight. (To test the back-up system, I flew around in the cruise on back-up alone for nearly an hour: all performed satisfactorily.)
Just as it is in the real P-51, the canopy is wound open and shut with a crank handle on the right-hand side, just below where the hood and windscreen meet. The hood is locked in place with a small red locking catch on the opposite side.
Starts on the button
To start the engine, it’s throttle closed, propeller fully forward and fine, throttle friction tight but not wrist-breakingly so, fuel on, fuel pumps on − and they stay so for the duration − fuel boost on − you can hear the whine as pressure builds − and then, as the note changes as it reaches the set value, fuel boost off.
The Suzuki always starts on the button − or key-turn − within the minimum of blades and runs sweetly. Initially there was a low rev-band harmonic which shook the instrument panel, but this has gone away with running. The engine may only be a V6, with paired stubs giving the illusion of twelve cylinders, but its warbling beat sounds even and holds rich promise for the coming flight. The 2.75:1 reduction gear brings propeller speed within sensible limits. The RPM dial in the cockpit shows engine revs and the agreed (and rather conservative) limit of 5,200rpm places the prop speed at a tad under 1,900rpm. There is also a manifold pressure gauge, calibrated in inches. This being an unsupercharged engine, the maximum power indication on take off will be close to 29.92” (1,013HPa for the metric generation).
With the aircraft trying to scoot forward when the prop is cycled from fine pitch at 3,000rpm and 19” to 2,500, you will be pointy-toed on the brakes trying to keep her steady. The MAP rises way more than you would normally expect, to 26”, and the propeller’s note drops from an alto voice to something near a tenor.
The return to 3,000 tails off markedly as speed reaches 2,900 and it takes a long 15 seconds or so before the propeller returns to fully fine pitch − but it is worth the wait to be assured that full performance is available for takeoff. Prior to takeoff, trimmers are set to neutral − there is no need to offset the rudder trim in anticipation of a massive swing. Indeed, if you can handle a tailwheel RV, Stampe, Tiger Moth, Chipmunk or something similar, your takeoff technique will work well − just avoid any temptation to give it a fistful of power and raise the tail straight away...
My cautious initial technique was to roll forward with the stick back, applying progressively more power and right rudder to keep straight, and when it felt right − with the indicated speed reaching the 30mph mark − raising the tail to place the nose just beneath the horizon, only then pouring on all of the remaining power. More recently I have had the confidence to open up slowly to full power tail-down, allowing the aircraft to break ground early.
A very noisy environment
At full power with the prop lever fully forward you can expect 5,200 rpm and a very noisy environment. Soul-stirring though the sound may be, only a brief acceleration in ground effect and climb can be made before exceeding the undercarriage and flap settings. Normal climb speed is an indicated 90mph. 200ft is deemed safe height to raise the first stage of flap − requiring nothing more than a blip of the coolie’s hat to retrim − and retract the gear − head down, identify and place your left hand firmly on the selector and raise the wheels as described earlier. Throughout this process only gentle right rudder pressure is needed to keep the balance ball between its lines.
The initial rate of climb is 1,480fpm. My notes say that it takes five minutes to get from 1,500 feet to 7,160 feet, producing an average rate of climb of 1,132fpm and mid-point climb rate of 1,100fpm. Into the cruise attitude but keep the power on and let the speed climb. Re-trim as you go, remembering that the faster you go, the lower the nose attitude will be − so re-trim again. If you throttle back to cruise power too swiftly as you level off, the speed seems to settle to a good 20mph less than you might be expecting: better to keep climb power on until 5mph short of the target 150mph (130kt) and then throttle back to the top of the MAP green arc (26”) and top of the green arc for engine revs (4,200). The highest level speed I have recorded is 160mph, with 27” and 4,000 rpm. This was at low level: when an unsupercharged engine like the Suzuki is operated at greater altitude it loses, in rough terms, 3/4” MAP per 1,000ft.
Surprisingly not much rudder is required for a change in power or speed and so it is best to leave the rudder trimmer in the neutral position and maintain balance pressures with my feet. The ailerons don’t exhibit much adverse drag to yaw the nose away from the turn either − still I do like to try and fly in balance all of the time.
At this point, if you haven’t done so already, drop your shoulders and relax. You have earned the superb view and the sensation of flying the Titan Mustang. Smile to yourself, as this really is a fun experience! Look along the silver wings, look over the nose, scan the sky and savour the moment: it is beautiful to be here.
On Titan’s website the company claims to ‘provide an aircraft that combines friendly low speed handling characteristics with agility and high performance,’ and for the most part, I have to agree. The wing isn’t quite P-51 shaped: it is a bit short and doesn’t have a laminar flow aerofoil section either − but the ailerons bestow a fair rate of roll and the turn radius is certainly small.
The T-51’s manoeuvrability certainly showed itself well in formation breaks and rejoins during the air-to-air photo session for this feature. It might be a great aircraft to have an aerobatic clearance, but I feel this will not be an overnight job here in the UK. Wingovers are a delight and the turning circle could be exploited in ‘flat’ air displays. From straight and level, with the aircraft trimmed to fly at 1.3 times the book figures and decelerating at one knot per second, the T-51 stalls gently and wings-level at 62mph (54kt). With take off flap, this reduces to 59 mph and with full flap, 53−but in this configuration there is a slight right-wing drop of 10° or so. Be wary; there is very little warning buffet, felt through the stick.
The Titan Mustang’s cockpit canopy appears to be a bit over-scale, even when compared to the ‘big-canopy’ training version of the North American original, the TF-51. I point this out as the original high-back Mustang had a lot of keel area that aided directional stability. When this was removed for the D model and a bubble canopy was installed, the aircraft lost some of its directional stability. The fix was to give the fin a fillet that restored the situation. Returning to our Titan, I think the canopy is just a bit too large for the size of fin, although not so much so there is a handling problem−just something to be aware of when releasing rudder from a sideslip.
What can be a problem though is something I alluded to earlier−that on approach there is a corner to be aware of. With full flap and approaching at the generally accepted 1.3 times stalling speed in that configuration, 69mph, first you cannot trim the aircraft−stick force is higher than generally expected−and second, the sink rate has to be experienced to be believed. Even at 80mph in the glide, the round-out has to be commenced early and with good anticipation, as the elevators are not very effective. Better to approach power-on at 80, using no more than the third stage of flap and wheel, or half-wheel the aircraft on. (I was happy to three-point but until Titan have completed the drop test for LAA acceptance I avoided this kind of landing).
Once the mains are on the grass, there is a momentary ‘tipping forward’ sensation caused by our soggy runway: I don’t think it would ever trip you up, but perhaps on long wet grass the effect would be more pronounced. The undercarriage is moderately short-coupled but the brakes are effective. When the tail drops observers have said that the rudder looks very close to the ground. However, as no scuff marks have appeared on its base, the little clearance there is would appear to be sufficient.
A delight to fly
To sum up, both the Titan T-51 kit and Ben Chester-Master’s individual build are the result of a great deal of hard work. Ben’s particular machine owes its existence to continuous liaising with the authorities by a chap with push and drive. It is a delight to fly and I am pleased to see him gaining more confidence and hopefully a bit of joy and satisfaction with every flight. It is marvellous that his wife and family have been so supportive throughout the task and I would like to thank all of them for their hospitality and allowing me to fly The Millie G.