Despite having had the aeroplane for some years now, we have not, until now, used it to actually go on holiday. Our April holiday plans were extensively disrupted by the different (and constantly changing) kids’ term dates. My son also insisted on going to his residential community service camp (who are we to stand in the way of community service?), and this meant that a family holiday was out of the question. And thusly it was decided that the two of us would head away for a couple of nights in the Madikwe Game Reserve.
Madikwe is only about 250km in a straight line from our house but by road it’s closer to 300km and can take up to 4 hours. With two airstrips in the park it seemed like the ideal opportunity to fly there.
As much as May is a flying administration month with medicals and license renewals (did I mention it took 9 weeks to get my license renewal back from submission to collection?), August/September is annual time.
Last year I had a big shock in that I had to pony up for the 5yearly rubber hose replacement, so I was hoping for a less significant annual inspection this time round. Annual time is funny, because it forces one to take a look at the hourly cost of ownership of the aircraft for the previous year – and this obviously depends on the number of hours flown. So the denominator this year is much lower than last year because of the lockdown. Last annual year I flew 65hours. This year, 44…
In a previous post I described the limited flying that we had been allowed to do – one ‘maintenance/engine preservation’ flight per 28days. After significant lobbying by the Aeroclub of South Africa and a slight relaxation in the lockdown regulations, this restriction has been lifted to some extent.
We are now permitted to fly unlimited flights per 7 day period, provided we take off and land at the same airfield, do not disembark the aircraft at any other field and carry no passengers. There is also a requirement to have hand sanitizer on board, to wear a mask and gloves and to thoroughly sanitize the aircraft between flights. A simple online form is required to be completed every week in which we agree to do these things and the weekly flying permit is issued.
Last weekend I attempted to fly yet another ‘maintenance/engine preservation’ flight as allowed for by our Commission Against Aviation. It had been 29 days since I knocked off the rust and it looked like the perfect day for aviation.
However, the weather had other ideas. A cold front was blowing in from the Cape and as is typical with our cold fronts, by the time the arrive in the hinterland they are devoid of cloud. What it was not devoid of however, was wind. Our runway runs 31/13 and the wind generally comes from the south in winter and the north in summer. On this day it felt breezy but not unmanageable.
I think my aircraft may have forgotten me. The last time I flew was with my daughter on Christmas Eve. We did at least do this properly by wearing Santa hats and by going for milkshakes at Rand Airport (FAGM).
The other day I offered to help one of our club members to move his aircraft to another airport for its MPI/Annual. No problem, right? Except it’s a controlled airport I’ve never landed at before (at least during the day – I did a touch and go there on my night cross country but the tower was closed).
This did give me some room for pause – it’s an easy airport, 2 runways, wide runways but there are some issues. Firstly, the airspace is busy – there are a lot of flying schools on the field and a fair number of commercial GA operations. Secondly, the airport is crammed tightly against the Class B (TMA) airspace of O. R. Tambo international airport (FAOR) and they don’t take kindly to bugsmasher’s violating their territory.
It’s a public holiday – Worker’s Day and those of us who work are restless to get some air between us and the ground. There is some discussion in the club WhatsApp group about a suitable location for breakfast – some guys want to go to Thabazimbi for the NGK Meifees (May fest) but many of us are a little twitchy about flying to a town airfield and leaving our aircraft there, being transported to the festival ground and having to rely on folk to bring us back to the planes again.
All good things must come to an end and this includes congresses – well, OK, being at a congress (even one dedicated to anaesthetising small people) is not as good as not being at a congress when in Cape Town, but it was still worthwhile.
There was a huge amount going on from a social point of view but was able to have dinner with an old friend and her family and also to have the most expensive cocktails I have ever drunk – I know it’s Cape Town but R130 for a Mojito is somewhat excessive – it is one of the trendiest spots in town though and the views and architecture made up for the cost of the drinks (almost!)
I’d deliberately left an extra day to get back – my plan was, if the weather looked at all dubious on the Monday, I’d aim to fly halfway back on Sunday afternoon, use the night rating to land late in Bloemfontein and sleep over and hop home on the Monday. My weather guy seemed confident that weather would be excellent on the Monday – with the proviso I left early ( 0600 local). This seemed to me like an excellent plan – despite the logistical problems of accessing the airfield at that time (beyond the scope of this piece).
I was surprised to wake up to a thin layer of cloud, which got thicker as I descended down from Rondebosch to the peninsula and headed north to Morningstar. The logistical issues of accessing the airfield at 06h00 were left by the wayside as conditions were low IMC with 1000m visibility but, annoyingly the clouds would break up every few minutes to reveal that the layer was temptingly thin. I could feel the get-home-itis starting to build. It would be very easy to blast through a hole in the clouds, but what if I needed to return? I doubted I’d be able to find the field again, so in consultation with the weather briefer we decided to wait 2hours. This allowed ample time for a very thorough preflight, at least 2 pre departure visits to the bathroom and sorting out returning the hired car to the AMO/FBO.
At 8h30 there was much more blue sky than low cloud and I decided the time was now. I taxied out, did my run up and launched off of 02. Climbing through 300ft the EGTs all climbed rapidly through 1100deg – well into the red. It took me about 3 seconds to decide that I was not continuing with this – reported returning to the circuit and got IBM onto the ground as soon and as safely as I could – I will confess that my circuit was not textbook but I was keeping it tight in case the engine quit. Bizarrely the power output felt ok and there was no roughness at all.
I had the AMO check it out – they ground ran it, and then we test flew the plane again – we were unable to replicate the problem. A possible theory was carburettor icing (there is no carb heat on the Sling and conditions were favourable for development of carb ice) but there was no discernible power loss so I’m sceptical of that. Another theory is that I didn’t put the mags completely back to BOTH but again, I don’t believe this and once again no issue with power. So I’m at a loss as to what happened, but there have been no abnormal indications since then.
Date of Flight
12 November 2018
Morningstar to FATA(Tedderfield)
The nett result of all of this is that it was 10h15 local when I departed, a good 4 hours later than I had wanted. I was hoping for a smoother ride than coming down but was to be disappointed. Initially the air was fantastic and I was settling in for an easy trip but as I approached Sutherland the thermal activity started with a vengeance, as it had on the trip down. I climbed to FL95, where the density altitude was 12750ft – I didn’t believe I could justify a climb to FL115 without supplemental oxygen, so I was properly stuck.
It may be something I need to get used to and there may well be a technique to riding the thermals to get maximum efficiency. I think it may be easier in an aircraft that cruises below Va – the Sling will easily cruise in the yellow band – I was having episodes where I was 5-7.5deg nose down, climbing at 700fpm and rapidly approaching Vne, so I would pull throttle to idle, ride out the thermal and then try to time reapplication of throttle to not end up on the back side of the power curve – occasionally I needed to put the prop into climb and once had to put the throttle though the ‘gate’ to 115% power to not sink. This suggested to me that I was not only contending with updrafts but downdrafts as well.
This continued for the rest of the trip – to say it was tiring is an understatement. I was again fortunate to be cleared through the Kimberly (FAKM) TMA which cut about 30miles off the trip. Most worryingly for me and the primary reason why I chose not to stop and take a break was the possibility of thunderstorm development. I was overhead Kimberley at about 13h45 local and had planned to already be in my car driving home from the airport by that stage.
Looking at the radar download I could see that there were some cells starting up so I elected to continue. Approaching Potchefstroom there were definitely cells but they were isolated so was able to manoeuvre my way around them – it is so tempting to fly underneath them but there was a lot of Virga about and I know well that that implies severe downdrafts – best avoided. So we picked our way through the cells. Typically I was unable to raise any cell signal to download the current radar pictures – man I wish we had a decent ADS-B in solution provided here. ATC was fairly noncommittal, “yes there are some buildups but they don’t look too hectic” – easy to say sitting in a comfortable chair.
Finally I was able to call overhead Tedderfield – had a bit of a fiddly landing as the gusts were starting up prior to a storm arriving but safely down and then the big job of unloading the aircraft.
5.9hours in a single leg is a long flight – it would have been better with less turbulence. I learned some important lessons though – leave as early as possible if possible, and rather leave a day earlier if there is any doubt about the weather. If I was to do this trip again (I’m sure I will), I will land at Cape Town international (FACT), suck up the higher landing fees and then be able to (a) access the aircraft whenever needed and (b) be able to depart before sunrise (Morningstar has no airfield lighting).
For a first long cross country trip I think it went really well. It had moments of frustration and times when I was quite anxious about the effects of the turbulence on continued flight. But that feeling when your destination comes into view after a long trip and you know you’ve made it? It’s fantastic.
So I have a new type on my license – and some endorsements to go with it! I recently spent two days at Wonderboom Airport (FAWB) getting rated on the Sling 2.
The Sling is a locally (South African) designed and built aircraft. It’s nominally a light sport aircraft but as configured it requires a PPL to fly as the maximum takeoff weight is over 600kg. Interestingly the same aircraft, with one wing tank removed will have a MTOW < 600kg and can be flown on a recreational pilot license as a light sport airplane.
It’s also quite different from the Cirrus I have done all my training on to date. Of course, it’s much lighter, all metal and has a significantly different engine? How different? Well, it’s a Rotax 914 – a 1.2l 4 cylinder producing 115hp compared to the Continental 0-360 6 banger on the Cirrus. It’s also turbocharged and the prop is a variable pitch constant speed unit (Yes, the Cirrus had a variable speed CSU but with no direct pilot control). Importantly, it burns MUCH less fuel – 20litres per hour compared to the 50-65litres per hour on the Cirrus. And it will burn MoGas happily too.
To obtain the conversion onto the Sling was not an easy matter. Firstly, there are a lot of flight schools operating Sling 2s. There are only 2 in the country that have the Sling 2 914 Turbo on their ATO. Thus I had to travel to Wonderboom, which is a great airport. Unfortunately it is 90km from my house. Not so good. I did the conversion through FliteCare who were fantastic – they could accommodate me at short notice, and their desk staff were amazing.
I first needed to have briefings on the Sling aircraft itself – concentrating on the many differences between it and the Cirrus – this took about an hour, then it was time to dive into the nitty gritty of turbochargers and variable pitch propellers. Turbochargers are easy to understand – once you figure out how the wastegate works and the differences between the hot and cold sections. The variable pitch propeller on the other hand I found to be a lot more complicated. It’s bloody brilliant engineering but seems very complex. My biggest problem is remembering the difference between fine and coarse pitch which I find counterintuitive.
As it turns out, the intricacies of the variable pitch prop are moot in the Sling because it has a very clever system to adjust prop pitch. Firstly, instead of being controlled by oil pressure and springs, the pitch is adjusted electrically by servos in the hub. And there is no pitch lever as would be suspected, but a pitch control instrument on the panel which has a knob to select T/O, Climb, cruise, hold, and Feather. One can also bypass the selector and adjust pitch manually should the control unit fail – this is done with a rocker switch. Once a setting is selected, the CSU adjusts pitch to maintain the required RPM on the prop. Because the Rotax is a geared engine, engine RPM does not directly reflect prop RPM – so prop rpm is not set, but the CSU will indirectly control engine RPM.
Speaking about engine RPM – this is high! A regular aviation mill will turn at about 2500-2700RPM. The Rotax idles at 2000 and will go all day at 5500. An interesting feature about the 914 is that full power is actually 100hp with an additional 15hp available when you push the throttle through the gate – allows 115hp for up to 5min – would primarily be used for takeoff and initial climb to 300ft AGL and obviously for the go-around. In the gate position the engine is turning at 5800rpm.
After the briefings, it was time to fly. The conversion requires upper air work, simulated engine failure and at least 5 landings. Preflight is fairly standard with the addition of a prop control unit check – cycle from full fine to coarse with the engine off (remember those electric servos?). The other very different aspect is the dry sump oil system – oil is stored in the oil tank – so in order to check the oil one needs to ensure all the oil is in the tank and not in the crankcase. This involves turning the prop by hand (check mags off, key out master off first!) until the telltale gurgle from the tank indicates that the oil has returned.
Dragging the plane out of the hangar is a one man affair – really a pleasure. Startup is a non event – fuel pumps on, fuel on and crank. It literally starts like a car engine. Run at 2000 until oil pressure settles then warmup is at 2500 until oil temp reaches 50C. Operating temps are much lower than conventional engine due to the hybrid air/water cooling system.
Taxiing is much simpler than the Cirrus due to the direct nosewheel steering – so much nicer than the free castoring nosewheel. She’ll roll 2 up at 2500 so the engine can warm nicely en route to the run up bay. Most pre takeoff checks are done on the taxi as they have a reputation of getting quite hot while idling stationary. In the bay it’s final checks, run up at 4000RPM checking the mags (<300drop and <115between), takeoff briefing and then it’s time to fly.
The best word to describe takeoff is “sporty”. Stabilise at 5500RPM and 100hp then through the gate to 115/5800. Lots of right rudder is required and before you know it, we’re at 48kts and the rotate call. Liftoff at 55kts and best rate at 75 has her climbing away comfortably at about 1200fpm. After takeoff checklist includes setting prop to climb, coming back out through the gate and cleaning up the flaps.
For the conversion we set off to the general flying area – steep turns are a non event – very easy to keep the nose up. Stalls are reasonably benign but I did detect a slight tendency to drop the wing and not a huge amount of buffet. The (brilliant) MGL Avionics iEFIS unit has an AOA indicator too which is helpful.
Then we did some circuits at Freeway airfield – which has a massive runway which is gravel. Also a non event for the Sling. I may think twice about taking an aircraft I owned onto a gravel strip but certainly it wasn’t an issue on this plane.
Back to Wonderboom with me having no idea at all of where I was – fortunately the instructor was at home in the airspace. The plan was to do a couple of circuits, but this was foiled by a medium sized Cb cell which decided to discharge itself over the airfield. Conditions on landing were challenging to say the least – significant wind shear and gusts from about 15degrees off the front of up to 25kts. The Sling handled this with admirable aplomb.
Sadly this meant I had to make the pilgrimage to FAWB again to finish the rating. We banged off 4 circuits easily in the mid morning this week – 2 normal landings (Flap 20), 1 flaps up landing (would really rather not do those….) and 1 short field stop and go. The procedure for landing the Sling is similar i believe to the C172 – cut power just short of the threshold and glide it in. You can’t do that in a Cirrus.. The short field landing we did just to demonstrate it – in the POH it says “short field landings as per normal landing” since the landing distance is about 270m. However, we did a short field approach – flaps 30 and standard piloting, stopped on the runway, and then did max performance short field takeoff – full throttle, brakes off, through the gate and full back pressure on the stick from the moment rolling starts. The nose wheel lifted of at 20kts and we broke contact at 48kts. Lower nose to Vx (75) and then up and away. Very impressive, especially when you look at the airport diagram and see how short the distance was – we landed on 29.
It’s really nice to have excess power available. So I’m now rated on the Sling2 and have endorsements for turbocharged engines and variable pitch propellers. Onward and upward!