The South African chapter of the Experimental Aircraft Association is celebrating it’s 50th anniversary this year. Every year there is a flyin to the Brits Airfield (FABS) but this year promised to be even more special. Any excuse for a flight is a good one, so it was off to Brits I went.
As summer starts to take hold it’s getting light earlier and I was able to pull the plane out at 6h30, in pleasant conditions with the low morning clouds clearing away and only the slightest breeze. I should have realised it was too good to be true…
As I rolled down runway 13 (into the sun – of course…) I noticed 3 Guineafowl taxiing out onto the runway ahead of me. Now a guineafowl is not a small bird – they probably weigh around 4 kilograms and stand about 35cm high – I didn’t fancy the idea of one of them going through the prop or hitting a wheel. In retrospect I made the wrong call by rotating 2-3kts below nominal rotation speed (50kts) but IBM eagerly kept into the air and disaster was averted. It would have been better to stay on the ground, wait for normal rotation and try to ignore the birds than to take off early and potentially stall out. Fortunately I was so close to rotation speed that it made no difference but definitely something to think about for lower speed incidents – better to hit a bird on the ground than stall it in.
The other concern is that the birds could have tried to fly and then I may have been in the situation where I’m flying at low speed and then hit a bird….
Bird excitement behind us, we climbed up under the Johannesburg TMA – cruising at 7500’ and routing to the west of the Lanseria class B airspace. We passed over Orient airfield (a major gliding Mecca), but it was too early for the obligatory powerless landers in their funny hats.
This dogleg set up a more or less direct course to Brits – and a routing directly into the teeth of a not insignificant headwind – 30kts on the nose meant we took a lot longer to get to Brits at only 90kts over the ground.
For the (anticipated) large flyins, the CAA usually declare an Aerodrome Flight Info Service (AFIS) which means that the usually unmanned airfield is manned with a tower operator whose role is to ensure separation but does not give explicit landing or takeoff clearances – it’s a little bit strange – the landing clearance usually sounds like “ZU-IBM, number one on the approach, land at pilot’s discretion”. Anyhow, as it turns out they were only opening at 07h30 and I arrived overhead at 07h25. This resulted in some confusion with arriving aircraft coming from 4 directions and all trying to ascertain if the tower was open or not.
I really enjoy flying to new (to me) airfields. I’ve been wanting to go to Kitty Hawk since I got my aircraft. Kitty Hawk is located to the east of Pretoria – about 30min flying time from Baragwanath. It is a very active field with a large number of Vans RV’s based there.
The field has a little bit of a reputation as being ‘difficult’ in certain wind conditions. I’m always up for a challenge that fits within my personal limits and experience, so reputation aside, I felt it was worth the visit. I was able to muster up only one other plane from the JLPC crowd – Roger in his Turbo Arrow agreed to join me out of Rand airport for breakfast.
My aircraft is back from annual inspection – what they say about the first annual is all true, sadly – was a lot more expensive than I was anticipating due to the 5 year rubber change, but that at least is done (until the next time – when I may also be looking at a BRS repack……). On the plus side, my plane is back and fit for flying again!
On the basis of the sticker shock from the rubber replacement we decided not to do any cosmetic work apart form installing the sun shade film on the canopy which has helped a lot to keep the cabin cool. I did this myself – it only took 2hours to apply it – a very fiddly job but the end result is satisfactory and seems to do what it is supposed to. It’s a PVC friendly static cling film that advertises 5% visible light transmission. I think it looks quite nice.
Having an aircraft in maintenance does very little for the desire to commit aviation. Out of necessity (see previous posts on moving aircraft for maintenance), I had left my vehicle in the hangar when I took my plane to Tedderfield so I needed a lift back to Baragwanath – which Matthew kindly offered. Of course, why would anyone go to an airfield unless it was to fly an aircraft – and he was off to fly his (recently returned from annual inspection) Mooney M20C short body.
Matthew very kindly offered me a flight in the Mooney, to which I gave due consideration (about 500msec) and agreed. The Mooney is a very different aircraft from the Sling. The Mooney styling has always appealed to me, there is something about that forward swept tail and the low slung stance which suggests that it will go fast. The Classic Mooney has a very 60’s look about it (which it probably should!) – the very steep windshield and the ‘big gulp’ air intake are unique design features. Even this short body variant’s tail is very low to the ground and I must say that this would worry me quite a lot in the landing.
I’m getting a little bored with the in-cockpit got GoPro shots. I feel like there are only two angles really – either out the front or looking at the wing. While these do have some interest, I’m keen to try some external camera shots.
The problem here is airways going to be how to safely attach a GoPro to the exterior of the aircraft. Safety here is two pronged – one doesn’t want to interfere with the aerodynamic performance of the aircraft. Neither does one want to be responsible for GoPro sized dents in structures or people on the ground.
I’d imagine the CAA/Police/justice system works take a dim view of damage caused by falling action cameras. Additionally, you can’t simply attach objects permanently to an aircraft. With this in mind I’ve been looking at getting a mount to capture footage like this.
There are a number of options and ideas to achieve this. The easiest way is to simply use the GoPro suction cup and apply it to the wing. Look. The cup grips well. But I wouldn’t like to bet my GoPro on it. So that idea is out. Then there are some proprietary mounting systems sold mostly on Amazon – flightflix and nflightcam being the two most prominent brands. But they are really expensive, especially once shipped here.
So I thought I’d have a go at making one myself based loosely on the flightflix tie down mount.
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.
I was supposed to fly to Middelburg(FAMB) this afternoon to camp at the AeroClub of SA Airweek being held there this weekend. The weather, it seems, had other ideas.
I was delayed by 30min at work this morning and by the time I arrived at the airfield the storm line was developing. I hung around finding things to do on the plane until 16h00 local by which stage I could probably have found a route but the flying time would have meant an after dark arrival – and I’m not night current at the moment – not landing at an unfamiliar field at night thank you very much.
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!