JIM DAVIS SHARES THE DELIGHTS OF THE MAGIC GROB
(Text: Jim Davis Images: Guy Leitch) – There was this guy in Uitenhage who did his whole PPL on one drum of fuel. That’s 40 hours on 40 gallons, He was flying a Grob G-109.
The Grob 109B is a wonderful plane. Let me walk you round it and tell you what makes it so special.
ON THE GROUND
The first thing you notice is how beautifully smooth the finish is. There are no rivets or seams or joints. Every surface is like silk. Where surfaces meet, like the wings and the ailerons, the gaps are sealed with a special tape. This means no trickles of air can seep through to disturb the perfect flow.
Unlike its earlier version, the Grob 109A, you don’t need a hangar – the 109B’s wings fold and unfold easily and quickly. This means you can slide it in along the edge of someone else’s hangar. All it needs is a space 10.5m long and 2.1m wide. When you have wheeled it out of the hangar it takes less than 5 minutes to unfold the wings. The ailerons and spoilers connect and disconnect automatically.
The final touch in keeping the wings clean is the removal of the pitot head to the top of the tail fin. On the pitot is a little venturi that works a variometer – a fancy VSI that compensates for climbs and descents caused by changing airspeed. So it takes out the climb from pulling the stick back, and tells you about gains and losses in total energy from lift – essential for glider flying.
When you do a preflight you somehow feel cheated – there’s very little to inspect. There aren’t even fuel caps – the fuel lives under the floor behind the seats.
You can’t inspect the control surface hinges because of the tape over the joints. But you can move the controls and sense that solid feeling that comes from control rods, rather than cables.
I like to cycle the spoilers, or air brakes, as Herr Grob calls them. You lean inside and take a good firm backwards tug on a big blue-handled lever to the left of the pilot. This moves it out of its over-centre locked shut position. Pull it back through about half of its travel into the landing indent and watch the dive brakes sprout out of the top of the wings.
Near the root of each wing there is a little hatch so you can check that the lever which locks the wings in position is doing its job.
Round the front you check the oil, the air filter and the composite prop, and that’s about it.
On one preflight I found a huge black burn mark under both sides of the tailplane. Closer inspection revealed a very slight scrape mark up the leading edge of the fin. It turned out the previous pilot, a timid little man from Germany, had tried to fly it under some power lines. The lowest line must have missed the prop and canopy by millimetres before slamming into the tail, sliding up and breaking with a mighty flash, which cut off Mossel Bay’s electricity for half a day.
It’s a strong aeroplane
That reminds me – amongst my best flights ever were the annual eagle-counting flights that I did with Dr Robbie Robinson, boss of the Parks Board. We would criss-cross the Karoo for a couple of days, sitting perhaps 20 ft above the power lines, trickling along at 110 km/h (60 kts). I flew from the right hand seat, keeping us just to the right of the lines so Robbie could look down into the eagles’ nests and count the eggs.
Why would you use a nasty, noisy vibrating fling-wing, when you could do the job at a tenth of the cost in a magic Grob?
FLYING THE G109B
Anyhow, let’s climb aboard for a flight from George, along the coast, to Wilderness and back. You take the left seat. Up on the wing and then slide down into that super-comfy seat. Everything is just where you expect it.
Rest your left arm on your lap and the stick is exactly where you want it. Let your right arm lie on the rest in the centre, and your hand falls naturally on the throttle, with the trim lever next to it. Zees Chermans sink of everysing.
There are a couple of strange things. The big blue spoiler lever on your left does exactly that – it spoils the lift – which of course steepens your descent. The spoilers also cause drag, like flaps.
If you want to land the Grob like a glider then you throttle fully back and use the spoiler lever much the same as a throttle. Ease it back and you descend more steeply. Move it forward and the aircraft almost seems to accelerate, and descends more gently. So just think of it like a throttle to regulate your approach.
If you want to land it like a powered aircraft you pull the spoiler lever back into the indent position so the spoilers are partially extended. Then you get your right hand on the throttle and fly her in normally. In the event of a go-around take full power, level the nose and put the spoilers to bed. Easy.
It’s important to use one method or the other. One well-known instructor got himself snarled up while trying to combine both and swanned into the ground, breaking the undercarriage. Fortunately not my aircraft.
The other oddity in the cockpit is the pair of handles in the middle for the prop. One is on the end of a cable, like a lawnmower starter. You yank it once, at 120 km/h and 2300 rpm, and she goes into coarse pitch. A second pull at 110 km/h and 1400 rpm, and it goes fine. The other handle, which looks like a VW Combi handbrake, pulls the prop into feather.
There is no mixture control because it has automatic altitude compensation in the carb. This means that when she is cold you use a manual choke for starting. You can usually put it off very soon after the engine is running.
‘I quickly came to realise I could not live without a Grob’
Some Grobs have dual ignition and others not. I think it’s an unnecessary complication. It also adds weight and expense. Most of the time you really don’t care if the engine stops.
This reminds me of a SAAF flight test I did in my Grob, in Oudtshoorn. An important looking guy with shiny brass tortoises on his shoulders pitched from Ysterplaat. He made me do all the normal exercises and then closed the throttle at 4000ft above the airfield and declared, “Simulated forced landing!”
At first I thought he was joking, so I didn’t rush to do all the ‘immediate actions’ that he was hoping to see. He did a bit of frowning and scribbling on his clipboard before I realised he was serious.
I feathered the prop and asked him where he would like to land. He said the choice was mine, as he peered meaningfully down at the tar runway beneath us. I pointed out that I really would enjoy his input in the decision making process because, apart from Oudtshoorn, we could equally well land at George, Mossel Bay or Plett.
Eventually he dropped the pose, turned to me with a huge grin and said, “Just put the effing thing down so we can go and have a beer.”
I ought to tell you, while we are on the subject of the military, that I am not alone in considering the Grob a magnificent aeroplane. The RAF bought 53 of them for ab-initio training.
This means I don’t need to walk you through stalls (which are straightforward and preceded by a vigorous buffet), spins (which are not permitted) and steep turns (which are childishly easy). If the RAF thinks it handles well, I can only agree with them.
Sorry, I got sidetracked.
We were about to hit the starter for a local flight along the coast.
Actually when you do hit the starter things happen instantly – the prop fairly whizzes round and there is none of this graunching that one expects on Lycomings and Continentals. She fires immediately and idles sweetly at 1400 rpm. Slow idle is 800 rpm, but it is not smooth. It is a 2.5 litre flat four, VW based, Grob engine. It performs beautifully, uses no oil and is everything we would want our Lycs and Contis to be.
Taxiing, with a steerable tailwheel and toe-brakes, is a pleasure –mostly you don’t realise you are in a taildragger.
Viz over the nose is great, but there are two things to watch out for. Those wings are longer than you think, so you need to keep an eye on them. And when you turn they have considerable momentum, so she is inclined to turn further than you expect. Yet, unlike many taildraggers, she has almost no tendency to ground-loop. So taxiing is a doddle.
We have a 15 to 20 knot southerly wind off the sea so we will backtrack down the grass at the beginning of 20 (as it used to be). Takeoff checks are straightforward. When you come to ‘flaps’, there are none, but just confirm the spoiler lever is fully forward. Under ‘mixture’ make sure the choke is off and when you do ‘hatches’, both gull-wing doors pull in solidly and snugly as you move the levers forward.
For takeoff we line up nicely: a final check on the windsock, which is standing out stiffly towards us, and a glance up and down 29/11 to check for traffic. Now you move the throttle smoothly forward and use enough left rudder to keep straight – the prop turns anti-clock, seen from behind.
The engine revs easily and she accelerates smoothly. In this wind you can get the tail up almost immediately – but be careful not to lift it too high otherwise you will smack the prop into the ground.
We have 200m of grass before we reach the tar taxiway. About half way along this she drifts easily into the air at around 75 or 80 km/h on the ASI (a bit over 40kts).
The first aerodynamic oddity shows up almost immediately. It really doesn’t matter whether you climb at 100 or 120 km/h, the VSI sits solidly on 800ft/min even though we are carrying enough fuel to fly to East London. At gross she climbs at around 600ft/min.
After about half a minute we level off at 1000ft on the altimeter – 350ft agl. The end of our 1200m runway is still ahead of us. If we have an engine failure here we can do a brief circuit and land back where we took off.
‘An aeroplane that will glide to the horizon from circuit height’
But that doesn’t happen, so we level the nose, throttle way back and pull the prop into cruise pitch. Now we settle at 190 km/h (100kts) for a couple of minutes.
For general training we could climb to 4 000ft, reduce power, notch the prop into cruise pitch and potter along at 140 km/h, using less than two gallons an hour. But we are not doing that today – we are going on an economy trip instead.
As the Glentana beach appears it’s time to throttle right back, switch the mags off and feather the prop. Magic, beautiful, whispering silence.
Savour it for as long as you like. We are flying in lift caused by the wind off the sea sweeping up the coastal ridge.
As we turn left to follow the coast we realise what magnificent visibility we have in every direction, including down through the surprisingly useful floor level windows.
You keep thinking something must happen. We are soaring like an eagle. The engine is silent; even the Hobbs has stopped. It’s not costing a cent. We seem be breaking not only the laws of physics, but normal economic imperatives. Not so, keep in the lift and hold the airspeed anywhere between 95 and 200 km/h and not even the tax man gets a look in.
She is gentle and easy to fly. The wind off the sea is smooth and predictable. We can push the nose down and tuck in close to the ridge and she maintains 190 km/h. It’s exhilarating stuff – you just have to be careful to keep the left wingtip out of the bushes.
This is huge fun, but it is hard work, so let’s do it the easy way. Move the stick gently back and we sail way up above the top of the ridge. Get the speed to 95 km/h for minimum sink, and we potter along admiring the beautiful coastline and the majestic Outeniqua Mountains. Over the nose we see Wilderness and the lakes.
Now we have to watch out for the paragliders that populate the west end of the Wilderness beach. There is a cove in the cliffs which gives them plenty of lift. They circle there like vultures.
We don’t need that much lift so we drift out to sea and bypass them. But now it’s time to think about going home. We can go back along the coast or try our luck getting to the mountains and again finding lift from the rising air. Let’s do that. We have a massive advantage over ordinary gliders – if our plan doesn’t work we hit the button and go back under power.
I know it’s cheating – but hell it’s fun.
The mountains work and we are cooking with gas. Up we go and sail easily back to George, climbing all the way. I bet the tax man hates us!
We let the tower know where we are and he tells us to join on a left base. What could be easier? We glide quietly in, using the spoiler lever as a sort of throttle, and touch down gently on the grass at the beginning of 20. As the wheels touch, ease the spoiler fully back to kill the lift. It also applies brakes to both mains. We stop in the length of a football field.
What could be better than that? 40 minutes flying for a couple of minutes under power. The engine is stone cold and we have to use the choke to start up for taxiing.
I love it to bits.