FLIGHT TEST

Cool Cruzer

Clive Davidson flies the first UK completion of a variant of this traditionally STOL type, geared to a more traditional cross-country regime…

Photos by Neil Wilson

Flight Test

et me say that I have to admit to being

Lvery pleasantly surprised that I had been asked to fly Darren Weston’s Zenith 750 Cruzer so soon after it had appeared in Mike Slaughter’s Project News column. It was featured in last month’s issue, Darren detailing the build of this first LAA example to be completed in the UK, and here I am flying it the following month. Nothing quite like being up to the minute with news! The Cruzer is a natural development of what started as the CH701 STOL, what Zenair called a ‘Sky Jeep’ concept of an off-airfield aircraft, with the short take-off and landing capability of a microlight. The 701 first flew in 1986 and the kit remains in production, along with its next in line CH750

STOL, which was introduced in 2008 and is effectively an enlarged version with a slightly higher carrying capability.

The Cruzer’s curvaceous lines present a radically improved appearance over the type’s predecessors.

A move away from pure STOL

The CH750 Cruzer, introduced in 2014, moves development on somewhat further as although the fuselage is fundamentally the same as the 750 STOL, it has an all-new wing which embodies single struts as opposed to the double struts of the earlier models, and a different aerofoil that offers a claimed 20% improvement in cruise performance. It has also dropped the fixed-wing slats for a conventionally clean leading edge.

Standing at the trailing rear edge of the wing the flaperon may be rotated up and down, deflecting as aileron by 15°. There is however, no differential to counter the nose yawing as roll is applied – maybe it’s not required. The flaperons may also be lowered electrically symmetrically by 15° for slow flight, and of course still operate 15° as ailerons for roll control.

The tail surfaces are also new, gone are the all-flying rudder and rather quirky inverted tailplane of the earlier models, replaced by a more conventional fin and aerodynamically balanced rudder and symmetrical tailplane/elevators which, like the wings’ flaperons, are mass balanced.

The reasoning behind these changes is that the concept has moved away from the overriding STOL requirement to more of an on-airfield machine, admittedly with good take-off and slow speed landing characteristics, but also embodying that faster cruise performance.

Engines, from 80-160hp are permitted, and although in the US the list of possible power plants is quite extensive, the UK Zenair agents Metal Seagulls, now in its new facility at Haverfordwest, is able to accommodate either the 100hp and up Rotax engines, or ULPower’s 118 or 130hp motors, they feel the optimum engine for the aircraft is the 130hp ULPower unit, which experience shows provides excellent climb performance, and a 105kt cruise on less than 20 lph.

A trip to Spanhoe

We flew up to meet Darren at Spanhoe, between Leicester and Peterborough, with Patrick Carruth in his Britten-Norman Freelance, which has become our regular camera ship, having recently had an opening side window installed. The weather on the way up from Henstridge had been flyable, although pretty grey and miserable, but once there it improved into a much better day for air-to-air.

Darren had flown down solo from his home base in North Yorkshire, his first cross-country in the aircraft, having previously flown it only four hours, although the aircraft had been flown rather more as he didn’t carry out the test flying. No surprise then that he couldn't be pinned down to a set speed and fuel burn – indicated speed was between 80 to 90mph, 4,400rpm for 80mph and 4,800rpm for 90mph on the secondhand Rotax 912 ULS, which develops its 100hp at 5,800rpm. The engine drives a 1,730mm diameter ground adjustable DUC Flash 3 prop.

Although Darren has stuck with the single Y-shaped centrally mounted stick, the Cruzer also offers individual sticks as an option, it’s one of those ‘you pays yer money and take yer choice’ things, although the Y stick certainly provides for better cockpit access. The nicely trimmed seats can also be had with sliding adjustment, an option Darren has adopted. However, the standard seat bolts to the seat bed and you can ‘adjust’ it by having several hole locations in the bed, simply unbolting and moving the seat as required.

It has to be said that Darren’s aircraft was very well presented, internally and externally, our combined first impressions were all very, very positive. It is all the more credit to him as in his build article he commented that he hadn’t previously even built an Airfix kit. However, these later Zenair kits are match hole drilled, so I reckon he must have been a bit of a whiz with Meccano as a kid!

No brakes on my side!

A quick scan into the left footwell showed toe brakes above the rudder pedals, but in the right footwell, the side I was soon to be sitting, there were no brakes for me to use. At least the rudder pedals have direct steering, giving me at least some control on the ground from the right seat rather than a few panicky rudder jabs before realising I am onto a losing wicket.

My concern is perhaps heightened at the moment from undertaking the conversion of a friend from his former regular mount of a rather tidy Cessna 150 to his first owned aircraft, a lovely little Jodel D120, a classic taildragger of course. I like the Jodel but it can be rather skittish when flown from a hard runway and, pointedly for me, it also has no brakes on my side to try and arrest any deviation from the straight and seemingly narrow. However, the nosewheel equipped Zenair will undoubtedly be far more stable than a taildragger.

Somewhat more curvaceous

The Cruzer uses a spring steel main undercarriage and somewhat smaller wheels than it’s STOL siblings, and they are fitted with nicely shaped spats. The pleasantly curved nose cowling too adds to its appearance, as does the generously wide 42inches (1,067mm) wide at the hips cockpit, with seemingly acres of ‘glass’. The swing up

Above The view out of the aircraft is certainly enhanced by the expansive greenhouse effect.

Left The swing up doors and single wing strut provides easy cockpit access.

Below The nosewheel is steered via the rudder pedals, its suspension taken care of by an adjustable rubber ‘puck in compression’ system.

bubble doors also provide an overall increase in cockpit width. All in all, the Cruzer is quite a handsome machine compared to the rather rudimentary ‘fit for purpose’ approach of the earlier models.

The all up max weight is 650kg / 1,433lb, with the centre of gravity between 270 and 500mm aft of datum. Darren and I lumped together weigh 142kg, we have next to no baggage in the cavernous baggage bay behind the seats, and just over half tanks at 30 litres a side (55 litres each plus a seven litre header tank behind the pilot seat), placing us just forward of mid-range CofG at 579kg/ 1,276lb.

All aboard…

Entering the cockpit is simple enough, forward of the strut and with the wide up-swinging doors. The generous width means it is easy to sort out the seat belts and plug the headsets into the jacks on the bottom of the centre console. The ‘Y’ control column initially feels a little strange, and there is only one throttle – on the far left of the panel for the P1 position (a second throttle is an option). The pull-on choke is to the left of the throttle and the start button above it, with the trim switch, trim indicator and flap switch forming a vertical ‘stack’ just off to the right.

Continuing across the panel comes the first two instruments, a colour-coded Rotax rpm gauge in thousands, and a fuel pressure dial in Bars.

Next ‘column’ sees the large diameter airspeed indicator mounted right where it should be, just under the Below The flaperons on the Cruzer are shorter than on the STOL variant, not extending the full span of the wing. coaming where the pilot can see it by lowering his eyes slightly, and just to the left of it are twin USB sockets and two small warning lights – one the charging light and the other a low fuel warning light that triggers from the header tank and comes on with just five litres of fuel remaining.

Below the ASI is a small dia VSI, and below that a Trig 8.33 VHF radio. Central on the panel is a portrait mounted MGL EFIS with, above it, the carb heat and cabin heat knobs. No mixture knob is required as the Bing carbs fitted to the Rotax self-compensate for altitude.

On ‘my side’ comes the large dia altimeter at the top, a slip ball in a small round gauge middle, and at the bottom the radio-matching Trig transponder. All that’s left is the RAM mount for the nav iPad, with a second twin USB socket behind it. It’s all very tidy and uncluttered on its carbon fibre look background, easily understood too, even for a pre-decimal fellow like me, provided I don’t turn the EFIS on, although I’m getting better now I have the Cassutt and have something similar in that. Darren selected a page of engine monitors, very pretty.

On the centre console are all the switches and circuit breakers, the key operated Master and 1 and 2 ignition switches being on the top row.

The whole internal area is both smart and neatly finished and is light and airy. Despite having a high wing, it has a completely clear skylight to see overhead, those lovely clear doors, and three quarter rear clear panels to see to the rear. A final scan inside finds the placards, with a reminder that ‘aerobatic manoeuvres are prohibited’, as is intentional spinning.

Let’s get flying

Strapped in and doors latched – a substantial locking handle midway along the bottom edge of the door and a smaller latch at the front bottom corner – we are ready to start. The Andair fuel selector, situated on the side of the centre console, alongside the P1’s right lower leg, is checked ON, Master ON, electric fuel pump ON and pressure noted on the fuel pressure gauge. The throttle is cracked open and held to prevent its desire to creep open and, following a good look around – Clear prop! – both mags are switched ON and a press of the start button has Bottom ‘ZW striking in her metallic blue, the curvy decals helping to negate the rather boxy fuselage.

Below Flaperon mass balances are another change, considered needed due to the Cruzer’s higher cruise speeds. the engine starting immediately and initially set to 2,000rpm.

The charge light extinguishes and the oil pressure gauge on the EFIS starts to rise, and after a couple of minutes Darren increases the rpm to 2,500 as we wait for the oil temperature to show 50°C before throttling up to 4,000rpm to check the ignition circuits. The mag drop should not be below 300rpm with a difference between the mags of no greater than 120rpm. Volts are a tad under 14 and the ammeter is showing a positive charge. Yes, the EFIS is pretty but also very useful! Idling has the gauge showing a blink under 1,400rpm and then it is eager to run back to the mid-twenties.

Taxying on the grass poses no problems from my brakeless right-hand side. Steering solely on the rudder pedals is direct and quite normal, a little anticipation allowing for the drag of the wheels through the grass is needed when wishing to come to a standstill by throttling right back and pausing. On smooth tarmac though, I had to ask Darren to take control as she rolls very readily, and brakes are needed.

Pre-take-off checks complete, we line up after the camera ship and Darren showed how on take-off he has adopted the technique of initially placing his right hand across the Y junction of the stick and when established on the climb out, transferring it to the left branch of the Y.

Take-off and climb

The take-off run is published as being short, just 117 yards/ 107 metres and Zulu Whisky certainly behaved like a frisky puppy, lacking no enthusiasm to get up and go. There was little induced swing imparted and raising the nosewheel off

the deck, prior to rotation speed, she flew off in the low 40s, the aircraft quickly accelerating in ground effect and into an early climb to try and chase our photo crew. On departure, we could have either used a climb speed of 60mph, best speed to clear obstacles (Vx) or 70mph, best to gain height (Vy). However, trying to catch the more powerful and faster Freelance, we initially set 70 and once through 500ft edged the speed up a bit and cut the corner, but also needed to ask Patrick to slow down a bit. Although our climb had been somewhat non-standard, we probably made something of the order of 650fpm in the 70mph stage.

As we closed, I had my first few moments to gauge the control reactions and was quickly absorbed by the coming task. I had control with my left hand on the right branch of the Y stick, we were in good trim with no stick pressure to overcome. Rolling without rudder saw a little yaw of the nose swinging away from the direction of the turn but it was simple to adjust the footwork and get back into balance. I soon decided to change hands and fly with my right hand across my chest holding the stick by slackening my diagonal upper torso restraining belt, and lean forward a little so I could operate the single throttle with my left hand. I spent a few minutes getting the measure of this arrangement before calling ‘Zulu Whisky in the box’ to let Patrick and Neil know we were about to join in close formation.

Precise and predictable

The Cruzer proved precise and beautifully predictable to handle; both through the stick and rudder and in concert with the application and reduction of power. Throughout the exercises of being placed wide, closer, low and high by the Above The cavernous and carpeted baggage bay. Care will be needed with loading, both weight and CofG.

Below The instrument panel is neat and uncluttered thanks to the portrait mounted MGL EFIS. demands of the sortie, I was particularly enjoying being able to fly a well-built machine, with good handling and accompanied by the builder owner.

We chatted about how he had come to build the aircraft and having worked on motorbikes and cars, this mechanically minded chap had many of the required skills and mindsets that are relevant to aircraft. It was at the LAA Rally that he met Jonathon and Patricia Porter of Metal Seagulls, and their enthusiasm, product and positive support proved to be all that was promised, right up to and beyond the very first flight that Jonathan successfully undertook on Darren’s behalf. Service indeed.

Left Conventional tail is so much less aesthetically challenged than that of its siblings!

Below Darren Weston with his recently completed aircraft. The first Cruzer to fly in the UK. diplomatically, but ‘lost’ is a rather more succinct way of describing the situation. One is always looking for helpful clues, such as the railway line and that marvellous feature of a viaduct near Spanhoe.

Part of the shoot had been over Rutland Water, and years ago I was again flying a photoshoot, during which, with cross controls and a wing low, the engine stopped. We were already at low level and made a short field landing on the edge of the reservoir, completely safely. We had been in a Slepcev Replica Fiesler Storch – and were wearing Luftwaffe uniforms. This last detail slightly unsettled, well that might be a bit of an understatement, the women who came over to find out what we were doing there. Being of a generation with fearful recollections of WWII, they didn’t hang around, but left wide-eyed and rather hurriedly.

Being given the thumbs up from Neil that ‘It’s a wrap’, we were free to break and explore a little further into the aircraft’s envelope. But first, a quick exchange with Patrick, who told us our position as we were, of course, not in our usual stomping ground. There is nothing quite like breaking formation, having been absorbed in the task only to find you have a very slim grasp as to where on the half million chart you might be! ‘Unsure of your position’ covers it

General handling

The comfortable straight and level performance figures returned an indicated airspeed of 83mph using 4,500rpm, whilst briefly applying full power to a wide-open throttle and trimming forward a few clicks on the electric trimmer, saw 105mph at 5,400rpm. Throughout the exercises the oil temperature remained within the lower half of the green arc of 75 to 110°C. Oil pressure sat at 4 bar/73 psi and the cylinder head temps remained within their recommended parameters of 80-90°C. As Darren hasn’t yet established any accurate fuel burn figures, he opts for a safe band of 15 to 20 litres an hour, and always carries at least 60 litres of

fuel before getting aloft, just to err on the safe side. From straight and level, the pitch stability is simply displayed by induced phugoids, increasing speed from a trimmed straight and level by 10kt by easing the stick forward and then letting go. These ‘ups and downs’ cycles slowly faded away and we returned to straight and level.

From wing low crossed control steady side slips, when released the lowered wing rises, showing a fair degree of lateral stability, but it was slightly slower than I had anticipated for a high-winged machine. Despite the large fin and rudder, the directional stability, although initially good, just at the last 5° or so of rudder travel there was a slight resistance in the system. Nonetheless the aircraft is comfortable in the cruise without constant attention being required to hold height, heading and speed.

Roll rates and stalls

With flap up and in the cruise at 75mph, from a stabilised 30° banked right turn to a 30° banked left turn takes two seconds, giving a pretty fair 30° a second roll rate. The reversing manoeuvre from left to right takes a half second longer, the difference may be explained by the prop’s direction of rotation.

At the approach to land speed of 1.3 of the stall speed, 63mph with flaps deployed, the roll rate naturally drops and reduces to 20° and 17° per second.

The application of the ailerons induces only a small degree of adverse aileron drag, allowing small rolling inputs without rudder to balance, but left up to a pedantic flying instructor he or she would probably be asking for perfect balance and a small input of rudder.

The ailerons are active right up to the approach of the stall, there being a slight buffet on the tail as the high angle of attack produces an increasing breakdown in the air's flow over the wing’s upper surface, which spills back to vibrate the tail and elevator. This can be felt through the stick and a gentle relaxing of back pressure returns us to normal flight. Stalls in gentle turns see her dutifully roll to wings level during the buffeting stage. Noted stall speeds were: clean 57mph, with take-off flap 54mph, and with full flap 48mph.

So, her manners are fine in as much as her stability is sufficient to allow the pilot capacity and time to view the world from a comfortable cockpit suited for its namesake, cruising. It is both economic and undemanding in operation.

I was interested in the aircraft types Darren had flown and how his transition to the Cruzer had been. He trained initially on the popular C42 and, licence in hand, moved into a Eurostar syndicate, which he absolutely loved to bits, it being a lot more responsive. It also showed him the variations in crosswind operation, crabbing with a low-wing rather than using the wing down approach as in a high-winger.

He has found the Cruzer heavier and was helped to convert onto type Alan Kilbride, an enthusiastic Jodel pilot who now shares his all-round expertise as an LAA coach, an outstanding facility to our members. Alan also undertook the test flying regime following Jonathan Porter’s first flight.

It speaks volumes for the confidence the aircraft gave Darren of taking a very newly completed aircraft on which he has only four hours’ experience, away from home base and I must thank him for his efforts in meeting us for a very enjoyable exercise.

It is a well-completed machine, an adventure still in the making for him. It is a credit to him, his family and helpful friends who made it happen. I look forward to bumping into him at the now not-too-distant Rally! ■

Bulldog Model 120 Statistics CH750 Cruzer with 912ULS

General

Overall Length: (engine and spinner dependent) 6.7m / 23ft 6ins Height: 2.8m / 9ft 2ins Wingspan: 9.1m / 29ft 9ins Wing Area:13.7m2 / 147 sq.ft. Empty Weight: 354kg / 780lb Fuel Capacity: (std) 120 ltr (with header tank)

Performance

Take-off Roll: (approx.) 107m / 350ft Landing Roll: 107m / 350ft Cruise: 190kph / 118mph / 103kt Stall: 62Kph / 39mph / 34kt Vne: 233kph / 145mph / 126kt Range: (std tanks) approx. 830km / 520 miles / 452nm

Performance figures quoted are from factory

prototypes at ISA.

ADS-BE SEEN WITH TRIG’S TN72

Use the CAA Conspicuity Rebate to upgrade your Trig transponder to ADS-B Out

Certified SIL 1 - Superior visibility Visible to all ADS-B In traffic devices Proven installation LAA / EASA CS-STAN

Be visible - be safe - fit Trig

CLAIM BACK UP TO £250 ORDER TODAY

Contact your Approved Trig dealer now www.trig-avionics.com