Airtest -Robinson R44 Astro

Unfortunately an unexplained fatal accident occurred in July last year (refer p88 Nov 93 AA) which set the programme back whilst Robinson and the FAA investigated the cause. No explanation could be found for the crash and although the FAA did not ground the aircraft, Frank Robinson decided to strengthen the lower collective and cyclic controls as a precautionary measure.

Production resumed and now stands at one to two a week but this will increase to five a week when the new production facility at Torrance in California, which is just about completed, comes on line. Extensive orders have evidently been placed from customers worldwide indicating that Robinson has once again found a market niche.

A final comment on the Robinson philosophy is that no product liability insurance is carried, Frank Robinson preferring to support his product through factory run, or promoted, safety courses worldwide.

R44/R22 Comparison

It must be stressed that the R44 is not really a scaled up version of the R22 but its design is based on the principles established with the well proven R22 of which over 2000 models have already been sold worldwide.

Fortunately I was able to compare the two aircraft as they sat side by side in the hangar and could see that although the lineage was apparent, they were completely different aircraft, with the R44 much bigger in every detail, even down to the ground handling wheels. In fact the R44 is almost as long, tip of main rotor to the stinger tail, as the Bell 206 Jet Ranger.

A final comment, and dare I say it, is that the overall appearance of the R44 makes the R22 look a little like a kit built machine. The R44’s engine is enclosed, and the skid legs are faired, imparting a more sophisticated appearance.

But then it costs twice as much! One thing should be made clear at this point and that is that the R44 is not a replacement for the R22, the two aircraft fill two separate market niches and complement rather than compete with each other.

eral two place light utility helicopter. The R44 is clearly a The R22 remains as the trainer, cattle musterer and gen- people mover with its four seats, relatively fast 110/115kt (205 to 215kmh) cruise at 75% power and 350nm (650km) (no reserve) range.

because of its 454kg (1000lb) payload and 318kg (700lb) hook However, there will be a slot for the R44 in agricultural work capability and this will no doubt be exploited as the aircraft becomes established. A spray kit is also available.

R44 Design Features

The R44 was designed to the newer, more stringent requirements of FAR Part 27 and as a consequence has greater crashworthy features such as energy absorbing landing gear which is capable of withstanding high vertical impacts; and lap belt and shoulder strap restraints designed for high forward ‘g’.

The aircraft is conventional in appearance with a tall, streamlined mast and quite low skid gear. The tail boom is stressed aluminium with the fin canted to relieve the tail rotor in cruise; there is a quite large and solid tail guard. The tail rotor rotates in the opposite direction to that of the R22 to improve left crosswind handling The electronic throttle governor, incorporated in later model R22s is standard on the R44 and makes a significant improvement in engine and rotor speed management, of which more later. The automatic clutch simplifies and reduces start up procedures and reduces the chance of an overspeed.

A rotor brake is standard and a safety cutout prevents the engine being started with the brake on. Instrument panel warning devices include low fuel, main gearbox temperature and chip lights, tail gear box chip light, low oil pressure, low voltage, low RPM warning light and horn, rotor brake and starter engaged lights.

The Robinson tri hinge rotor design eliminates lag hinges, dampers and hydraulic struts and the main rotor, which has a span of slightly more than 10 metres, incorporates a stain- less steel leading edge to reduce corrosion. Large 3. 2kg (71b) tip weights increase rotor inertia and provide consequent good auto rotation characteristics. In addition the main rotor disk is 3. 3 metres above the ground (rotors turning), which is a major safety factor.

The primary controls are manually operated push pull tubes which have maintenance free bell cranks. Retaining a manual control system on a two blade system with an aircraft MAUW of 1090kg (2400lbs) has necessitated compro- mises which were evident in flight, but of no great consequence as is discussed later.

The engine is fed from a gravity flow fuel system which eliminates the need for transfer pumps; the 120 litre main fuel tank is located on the left side and 70 litre auxiliary tank on the right.

The engine is the tried and true Lycoming O-540 which is derated from 260hp to 205hp and 225hp for takeoff (from 195 to 154kw, and 160kw for TO). This same engine delivers over 300hp (225kw) in a number of fixed wing aircraft so it is clearly understressed in the R44 which should ensure a long reliable life.

The extensive use of teflon bearings in conjunction with a simplified control system eliminates the need for scheduled maintenance between 100 hourly inspections and if experience with the R22 is a measure, unscheduled maintenance will be rare.

Flying the R44

It was a fairly warm and humid day with little wind and The aircraft is fairly straight forward to check and the syslight turbulence as we carried out the preflight walkround. tems are readily accessible through numerous access panels, with one of the latter strengthened for inspection of the rotor head. A nice touch is a facility to enable all the cock- pit warning lights to be tested from a panel located on the starboard side of the engine bay.

The aircraft sits very close to the ground with the cabin floor less than half a metre off the ground which makes for easy access to both the front and rear seats. The rear doors are held open via gas struts but for some reason these are not fitted to the front doors. All doors have rearward opening vents but no scoop arrangement which would be an advantage in our climate (I subsequently found a hand suit- ably placed in forward flight provided a measure of forced ventilation). There is a nose mounted air inlet but it didn’t fan forced ventilation would help to cool what is in effect a appear to help much in the warm humid conditions. Some hothouse.

Before our flight, I sat in the rear seat compartment to try it for comfort and vision and was well satisfied on both accounts. The rear seats are higher than the front seats and there are no structural members to obstruct forward vision. I must confess however to being slightly bemused by the Finally as with the R22, there is no separate baggage compartment but there is a fair amount of stowage avail-mounted in close proximity! Whoever designed this ‘fea- able under each of the four seats. As Bill Miller commented, if you are a golfer you will have to invest in collapsible sticks!

Maintenance Requirements

Extensive dynamic component testing has been undertaken so that similarly to the R22, the R44 already has a 2000 hour TBO for the engine and airframe, and all life limited components have approved service lives of at least 2000 hours. At 2000 hours (or ten years) the aircraft is rebuilt to zero time in a factory approved maintenance facility.

cigarette lighter and ash tray, with a no smoking sign ture’ might have better spent their time improving the ventilation system instead! The rear seat occupants can plug into a stereo system (for those with a need for music whilst airborne) and still remain on the intercom.

The front cockpit at 1194mm (an increase of 150mm on the R22) is a similar width at shoulder height to the rear compartment allowing plenty of room for movement. The seats are similarly as comfortable, however there is no adjustment provided on the seats or the controls which might cause a problem for the vertically disadvantaged.

The flight controls and instrument panel follow the R22 Following completion of the pre takeoff checks, including layout with the “T” bar cyclic making access much easiering the needles, Bill Miller lifted off and shortly after than a conventional floor mounted stick. The pre and post handed over to me to track to Hoxton Park for some hover- start check list card is stowed in a pocket at the front of the ing, circuit work and autorotations. Like all newcomers to right hand seat and the actions required are very similar to the R44 I had a little difficulty at first with the cyclic, tend- the R22. ing to overcorrect. I had been prebriefed on the system but it takes a little getting used to. Strain gauges sense trim loads and operate two trim motors which zero trim loads through springs connected to the cyclic. By its very nature it is lagging behind the aircraft and it is very easy at first to get out of sync by not allowing the trim system sufficient time to relieve the trim loads. The answer is to fly with a very light rein.

After start, the clutch switch is made which tightens the four transmission V belts through an electric screw jack, and belt tension is then kept constant by sensors. As with the R22, a yellow warning light indicates when the system is operating. Following clutch engagement, revs are increased to 80% for warm up, and when temps and pressures are in the green, the governor is engaged via a small switch at the end of the collective. The RPM rise to steady at 100% and that is where they stay, rock steady. I must confess to being very impressed by the governor, it is as good as any turbine, so much so that it could lead to complacency in terms of rev watching There is no movement in the collective but small movements can be felt through the throttle as the system does its stuff.

There is a coolie hat on top of the cyclic for fine trim but in my brief encounter I must confess I didn’t use it; perhaps as experience builds the need for fine tuning would become apparent. Having had only the briefest of encounters with the R22, and that some 18 months previously, I had forgotten that the teeter system allows you to place the cyclic grip where you like in the vertical plane and that it is best to fly VH-ARG HELIFLITE with your forearm on your knee. Once this was sorted out, my PIO (Pilot Induced Oscillation) input was significantly reduced and I settled down to enjoy the flight.

It was soon apparent on arrival at Hoxton Park that the R44 is a very slippery ship as it took some firm action on the collective to slow it down. Once below 70kt (130kmh), speed control was much easier and the approach to the hover was straight forward, with the excellent governor maintaining the revs dead beat. Heading control was easy to maintain.

Using a drain cover set in the grass alongside the strip as a reference point, I tried a few spot turns firstly around the mast and then with the nose on the point, and finally some turns with the tail rotor on the point. All were easy to coordinate as by this time I had started to get the feel of the aircraft and was no longer fighting the trim system. Sideways and backwards flight were equally as straight forward. Unfortunately there was very little wind so it was not possible to see how it handled in more demanding conditions.

One surprising aspect, which evidently most first timers have a problem with is the touchdown from the hover. The aircraft sits so close to the ground that you think you must be down but unfortunately you have another six inches to go! Once again a little experience in the aircraft would overcome this problem.

Finally it was time to try some autorotations.

One is reluctant to use the term ” glide” for a helicopter in autorotation as most tend not to advance very far when the main rotor is no longer under power. However, in the case of the R44 the term does apply because it has a very flat angle and covers a surprising distance in this mode of flight.

Bill demonstrated an auto from circuit height and again from the hover and it was apparent that there was plenty of energy in the rotor to achieve a smooth, unhurried touch down. This is a considerable safety factor.

On departure back to Heliflite’s pad at Castle Hill I took the opportunity to note the aircraft’s performance in the climb. At 70kt (130kmh) and with 23 inches we achieved a steady 1300 fpm, not bad performance even though we were relatively light.

On the way back, Bill ran it up to just short of the VNE of 130kt (240kmh) where naturally the vibration was fairly noticeable, however on returning to a more relaxed cruise of 110kt (205kmh) the comfort level was restored.

Shutdown at Castle Hill gave the opportunity to observe the rotor brake which brought the rotor to a smooth stop.

The R44 Summed Up

My impressions? At a flyaway price of $385,000 it is unquestionably value for money. Whilst it is not as smooth as a multi bladed, power control turbine, it must be stressed that it does much the same job for about a third of the price and a fraction of the operating costs.

The nearest equivalent new piston powered machine is the five seater Enstrom at not quite double the cost. Robinson has clearly done an excellent job of determining a market need, ie, a low cost (relative) four place people mover, and then designing a helicopter to fit that niche.

I don’t think I will be risking my money in betting that the R44 will prove to be the next most popular piston helicopter to the R22 in this country (and worldwide for that matter) as its capabilities become better known.