Flight test: SZD-45A Ogar
- Credit: NA
Noisy and ungainly on the ground, the elderly Ogar’s element is the sky where it performs gracefully | Words Dave Unwin - Photos Keith Wilson
As we float serenely across Rutland Water I glance across at Roger Pitman and grin wryly.
"You weren't joking were you Roger? It really does look like you're sitting in a deckchair!" "Well, might as well be comfortable!" he laughs in reply.
One of the great things about being Pilot magazine's Flight Test Editor is not just the quantity and quality of the aircraft I'm lucky enough to test, but also the variety. Some aircraft display almost national and cultural idiosyncrasies (such as the difference in handling between American and French four-seaters), and others even their manufacturers' political ideology.
Conceived in the depths of the Cold War and designed by SZD-Bielsko's Dipl.-Ing. Tadeusz Labuc, the SZD-45 Ogar (Hound) is a fascinating flying machine that I've long wanted to fly. It is also one of the most unusual-looking aircraft ever made.
While waiting patiently at Saltby airfield for it to arrive we all heard it before we saw it. And when we did see it we knew what it was, because it looks like nothing else! Featuring a pod and boom configuration, a high-wing, T-tail, and powered by an engine mounted at the back of the fuselage that turns a pusher propeller, it's unmistakeable.
The prototype first flew on 29 May 1973, and 64 production aircraft were built between 1974 and 1980 at SZD's factory at Bielsko-Biala in southern Poland. As part of the USSR, Poland had a centrally-planned state economy and sailplane design was concentrated here.
- 1 Civilian instructor qualifies as military QFI
- 2 Flight test: DHC-1 Chipmunk T.10
- 3 Flight test: Piper PA-23-250 Aztec
Szybowcowy Zaklad Doswiadczalny translates as Glider Experimental Workshop; all the design work was done by SZD and the aircraft produced here and at other state-owned workshops and factories.
As it taxies towards me I can't help but think how ungainly it looks, with one wingtip-mounted outrigger firmly on the ground and the other pointing at the sky. Then I realise that as the other wing really is a long way off the ground it would actually be easier to taxi than a T-61 or RF5B, as you don't need such a wide taxiway.
While I'm still processing this, it pulls onto the grass and performs a very deft 180 degree turn, in not much more than its own length! Anyone who's ever flown a T-61 or RF-5 will know why I put an exclamation mark at the end of the preceding sentence. It might look a little clunky on the ground, but looks aren't everything.
The prop stops and the large aft-hinged canopy swings open and back. I can see Roger unstrapping and preparing to disembark, then realise that the cockpit sills are extraordinarily high off the ground.
For the life of me I can't see how he's going to get out and - more importantly - how I'm going to get in. Suddenly, he produces a set of welded metal steps, which he carefully places on the sill and then climbs out. Amazing! One thing is already irrefutable, the Ogar is full of surprises! And as I begin to inspect it in greater detail the surprises just keep coming.
Some aircraft are made from metal, others composites or wood; well, the Ogar uses all of them. The cantilever wings are shoulder-mounted and of wooden single spar construction, skinned with plywood and covered with glass-fibre, while the fuselage pod which carries the cockpit, engine and tailboom consists of a glass-fibre shell over two load-bearing wooden frames.
Finally, the tubular boom which extends aft from the keel of the fuselage pod is made from duralumin alloy. The slightly swept-back fin is integral with the tailboom, and carries a large rudder with a cantilever T-tail on top. The fin is quite large, as is the rudder. The quickly-detachable tailplane is on top of the fin and carries a good-sized mass-balanced elevator.
The engine is mounted at the rear of the fuselage pod, aft of the wing's trailing edge, and at the same level. The prototype was powered by a 45hp Stark-Stamo engine, and I strongly suspect that (unless you were operating from the same runway as a MiG-21) it was soon appreciated that 45 horses just weren't enough for an aircraft with a MAUW of 700kg and production aircraft were fitted with a Limbach SL1700EC.
This is an air-cooled flat-four derived from the classic VW 'Beetle', and produces 68hp at 3,300rpm. It is fed from a single fuel tank of only thirty litres directly behind the cockpit, and turns a two-blade composite pusher propeller. Access to the engine is excellent. There are several inspection panels in the cowling, while the entire top half opens like a car bonnet.
The monowheel undercarriage consists of a mainwheel fitted with a cable-actuated drum brake, outrigger wheels mounted on flexible struts right out at the wing-tips, and a steerable tailwheel.
The mainwheel is mechanically retracted into the fuselage but, in common with many motor gliders (and some other Soviet-era aircraft such as the Yak-52), it only half-retracts. The upside of this design is that should you land wheel-up (either by accident, design or malfunction) no damage is done. The downside is that it doesn't reduce total drag by that much.
The tailwheel steering unit is supported by a phosphor-bronze bush which Roger describes as "a work of art, and almost as expensive!" I was already starting to get the impression that the Ogar had been built to a specification, not a price, and part of the plan was to make lots of work for lots of people. It's very well made, albeit somewhat over-engineered.
In another significant difference between capitalist and communist thinking, not only do the wings not fold, but I got the distinct impression that de-rigging would not be a trivial affair and would require the assistance of several comrades!
The wing section is quite sophisticated, it uses a Wortmann FX-61-168 aerofoil at the root, changing to an FX-60-1261 at the tip. With only one degree of incidence the wing is rigged fairly flat, and features a very slight sweepback.
The slotless ailerons are narrow chord, of glass-fibre sandwich construction and hinged internally. They are actuated by pushrods, as are the elevator and airbrakes, the rudder alone being cable-operated. Large Schemp-Hirth type airbrakes extend from the top and bottom surface of the wing at 45% of the chord. What really impressed me though was the quality of the workmanship. It is beautifully made.
This Ogar is based at Hinton in the Hedges and owned by a small syndicate, which Roger delights in telling me has taken the Ogar all over the UK and also to France on several occasions.
Access to the cockpit is unusual. As mentioned, because the sills are very high it carries its own detachable step. This system was a first for me (and I've flown a few types) and may even be unique.
If any reader has flown anything with a similar arrangement I'd love to know about it.
The canopy opens wide and is held open by well-damped gas struts. However, care must be taken not to use the canopy gas struts as grab handles, as they are too conveniently to hand. I would be minded to paint black-and-yellow stripes on them to deter would-be grabbers.
The cockpit is big, wide and very comfortable. The seats adjust over a good range but must be set in place before you sit down, although the rudder pedals can be easily adjusted in flight.
Furthermore, as the sticks and seats are slightly staggered the wide cockpit feels even wider as you're not constantly rubbing shoulders with the other occupant. Roger puts his seat right back, the pedals right forward and it looks like he's sitting in a deckchair!
Settling onto the comfortable seat, I like the uncluttered look of the instrument panel, which is as wide as the cockpit and has all the instruments laid out in a single row. These consist of a turn & slip, variometer, ASI, altimeter, tachometer, oil pressure and temperature gauges, and a cylinder head temperature gauge.
The latter is particularly important as there are inherent cooling problems with air-cooled engines in a pusher installation, and it was interesting to note that the CHT gauge is disproportionately large.
Both pilots have an air brake lever by their cockpit sidewall. The wheel brake is applied at the end of the airbrake lever's travel. In the central column which braces the instrument panel are a curiously shaped throttle, a choke, and a T-handle for the starter, with the ventilator control beneath, and the unusual Master switch at the bottom.
Interestingly, there isn't a carburettor heat selector. Between the seats is the lever for the spring-bias elevator trimmer, with the lever for the undercarriage further back. There is no warning system but the lever is large and tactile, and both it and the airbrake levers operate in the same plane as the throttle.
Simply put; push forward to fly and pull backward to land. This arrangement removes any ambiguity or confusion in operating these systems.
As for stowage, a large baggage bay immediately behind the seats is accessible in flight. It is located practically right on the centre of gravity, an excellent safety feature as it means you are unlikely to go outside the C of G envelope.
The engine started promptly and rather nosily, although I hadn't really expected anything less, as it's mounted up high on the wing to allow a low undercarriage while still providing good prop clearance.
An inevitable consequence of this type of engine installation is that it will be noisy. Firstly, you have an air-cooled engine situated quite close to your ears, and secondly, as with all pusher-type installations, the exhaust pipes are unavoidably mounted in front of the propeller disc, meaning that the exhaust is discharged into the prop, which chops it up, creating more noise.
Taxying out revealed, for a monowheel, good characteristics. The suspension seemed reasonably well damped, the brake adequate, and the tailwheel steering powerful and precise, as the turning circle is impressively small. With an outrigger on the ground the cockpit is well canted over, but I soon get used to it.
Lining up I note the ambient conditions, particularly the slight crosswind from starboard, as monowheels and crosswinds do not mix. The OAT is 20°C, giving a density altitude of about 1,100ft; so 160kg of pilots and petrol puts us within 55kg of the 700kg MAUW.
The POH emphasises that the stick should be fully forward at the start of the takeoff roll, something I would strongly advise against in most monowheels, because as soon as the tailwheel lifts you a) lose tailwheel steering and b) there's a strong tendency to yaw, due to the propeller.
However, with the Ogar, as the centre of thrust is also quite close to the centre of gravity and centre of pressure this isn't an issue. It takes a while before the elevator bites and the tailwheel leaves the ground; conversely, the ailerons come alive almost immediately, making it easy to balance on the monowheel.
Incidentally, another inherent disadvantage of pushers is that when taking off or landing in rain there isn't any propwash to clear the water off the windscreen.
I keep the Ogar balanced on the monowheel as the speed builds, then a hint of back pressure and it waffles into the sky at around 45kt. I hold the aircraft in ground effect until we have another ten knots then ease into a shallow climb.
Bearing in mind the Limbach is some 50% more powerful than the Stark-Stamo and the performance is still far from startling, the prototype must've been distinctly marginal. The climb rate isn't bad. Initially I wasn't overwhelmed, until I realised the VSI was under-reading, but it's certainly noisy - both in the cockpit and, as I noted when Roger departed, from the ground. The CHTs stayed within limits, but a long, slow climb would be inadvisable.
The regular crew of Al and Keith in the BGC EuroFox are already on station above the photogenic Rutland Water, and as Keith's door pops open I slide into formation with confidence.
This should be easy: the Ogar has big airbrakes, reasonable power, fair controls, and a tremendous field of view… what could possibly go wrong? Well it's time for another mea culpa moment. (Yes, the second this year.)
As the mainwheel semi-retracts I thought we would shoot a few shots with the wheel down and then some with it up to show how little it retracts, but the very high level of concentration required to fly close formation meant that I forgot to retract it.
However, Keith never indicated that the wheel was still down (and he always does when he wants the undercarriage cycled) which demonstrates quite clearly that, because it only retracts a few centimetres, it may not have shown up in the photos anyway!
Indeed, it probably doesn't make that much difference, as when I eventually retracted it before examining the cruise performance and then extended it towards the end of the soaring bit I couldn't discern any real difference.
As we sail above Rutland Water it occurs to me that the Ogar's pod and boom design is somewhat reminiscent of a Republic SeaBee, and that with its boat-like hull and pronounced keel it'd probably ditch well.
The cockpit is also very comfortable, and I wonder if SZD had their eye on the export market, as the comfy seats seem more suitable for the bourgeoisie than the proletariat!
With all the photos in the can I start my examination of the general control and stability characteristics. I pay particular attention to changes in pitch trim with power, because a well-known side effect of high-mounted pushers is that the high thrust line produces significant changes in pitch whenever the throttle is adjusted.
On the Ogar this effect seemed negligible, and easily trimmed out. It's a very stable aircraft, and the controls are adequate, although harmony less so. The stick is relatively short and the heavy ailerons need a firm hand at speed, while the elevator is quite light. The rudder is powerful and breakout forces reasonable.
The rate of roll is acceptable and visibility in the turn (and indeed every phase of flight) is truly excellent. An examination of the stick-free stability confirms my original assessment; it was designed as a trainer and the emphasis is much more on stability than control.
A ten-knot displacement from a trimmed speed of sixty knots produces a low-amplitude long wavelength phugoid that eventually damps itself out after several lazy oscillations. Directional stability is softly positive (unsurprising, as the pod-and-boom means there's lots of keel forward of the centre of pressure, despite the large fin), and spiral stability just barely neutral.
As you'd expect with any motor glider, the low-speed characteristics are very benign, and it just sort of mushes and wallows as the stall is approached, before the wing finally quits at about 38kt. The pre-stall buffet is negligible and recovery quick and easy, with minimal height loss. It stalls in the same way it does everything else; slow and friendly.
The Ogar is approved for spins and basic aerobatics, but as it's 45 years old I think it would be undignified to treat such a graceful old lady in this fashion, and turn my attention to the (relatively) high-speed side of the speed envelope.
First, check that the undercarriage is up after the photoshoot?Oops! Oh well, I confessed to that earlier. First the ball on the lever is pressed downwards to unlock the undercarriage, then the lever is thrown forwards through an arc to raise the wheel into the well.
There are no warning lights whenever the undercarriage is in transit, up or down. Personally, I'd recommend at the least that a buzzer sounds if the airbrakes are unlocked with the wheels up. Setting the throttle to 2,800rpm produces an IAS of around 65kt at 3,000ft, for a TAS of 71.
Increase the power to 3,000rpm and it slowly accelerates to 70, for a TAS of 76 while burning around nine litres an hour.
If you're interested in an old-school air-miles per gallon number, it's around 40mpg. Not bad, which is just as well as the single thirty-litre tank means you've only got six and a half gallons to begin with.
Even though the day is rather flat, with very little evidence of vertical air movement, I simply can't wait to turn off the engine, so as soon as we are within easy gliding range of Saltby (just in case the engine doesn't re-start) I reduce the power to 2,200 rpm for two minutes to allow engine temperatures to stabilise and trim for 55kt. Then its power to 'flight idle', mags off and slowly decelerate until the propeller stops turning at around 45.
It has been my experience that the wing loading of many modern motor gliders means that speeds above 55 knots are necessary to retain sufficient control authority, which makes it difficult to stay centred in an average British thermal.
However, the Ogar will thermal quite comfortably at fifty, and as we slide earthwards towards the pre-briefed engine restart height of 1,500ft I finally find a small thermal and scrape back up to 2,000. Great fun.
It really is an easy machine to soar, rather like a K-13. The book claims a best glide of 27:1@55kt, which felt about right, while the min sink is quoted at 190fpm@40kt. This may be slightly optimistic. After an enjoyable thirty minutes defying gravity, I restart the engine and join the circuit.
I find it easier to extend the undercarriage than retract it. I then briefly open the airbrakes to ascertain their effectiveness; they are certainly very powerful, and I quickly stow them until final. On the approach I trim for sixty with the throttle set to idle and control the glide path with the airbrakes.
Landing on the grass with a gentle crosswind is easy, the trick is just to ease the airbrakes in slightly as you flare, and aim to touch the tailwheel and mainwheel simultaneously. Pop the brakes back out when you're down and you'll stay down.
I would not recommend attempting a landing with full airbrake, as the sink rate is eye-wateringly high and you'll land with the wheelbrake on. Narrow tarmac runways and a strong gusty crosswind are a combination best avoided if laundry bills are to be kept to a minimum!
I was very taken with the Ogar, and in my opinion there is no comparison with its closest capitalist counterpart, the T-61.
The Ogar is superior in every respect. It's a shame the wings don't fold, (neither do the T-61's) but you could have a lot of fun with an Ogar exploring wave systems, sea breeze fronts and shearlines, and also hills and ridges that simply aren't accessible by pure gliders.
As I climbed out Keith and Al came over, and both seemed curiously animated. "You should see that thing in flight" enthused Keith, "it looks amazing!"
Al nodded enthusiastically in agreement.
Ogar is Polish for 'Hound' but I can't help but wonder if perhaps ?abedz (Swan) would've been more apposite.
It may be a bit of an ugly duckling on the ground, but it is very much an elegant swan in the sky.