Flight Test: Fabulous Fury
PUBLISHED: 10:24 03 July 2015 | UPDATED: 10:24 03 July 2015
Designed by ex-Supermarine man John Isaacs, the scale replica that is as pleasurable to fly as the original Hawker fighter of the 1930s
John Isaacs called it ‘Air Marshal’s weather’ – not our mediocre modern CAVOK of 10km visibility and 5,000ft cloudbase, but the good old CAVU (Ceiling And Visibility Unlimited) so appropriate to this seventy-per cent scale inter-war fighter. Furthermore, there are ten-to-fifteen knots of wind straight along Old Warden’s Runway 21, making conditions utterly perfect to point this pretty yellow and silver biplane into the bright blue sky where it belongs.
Heeding owner and stalwart friend Jonathan Marten-Hale’s advice not to move the control column forward too soon, I gradually open the throttle, squeeze a little right rudder and let the tail rise of its own accord. Before I know it, we’re soaring into the air in a taut little capsule of wings, struts, buffeting propwash, roaring slipstream, barking Lycoming and singing wires.
I haven’t worn a watch since retiring from British Airways, and with the joyous prospect ahead of open-cockpit aerobatics, I’m not carrying anything in my pockets, so I have to rely on the VSI to tell me we’re rocketing heavenwards through the gusts and bumps at a truly interceptor-like 1,600 feet per minute at the best climb speed of 65 knots. Old Warden’s broad green turf rapidly drops away and a wide smile suffuses my windswept cheeks. An open cockpit is the only place to be on such a perfect day.
As I ease stick and rudder leftwards, we curve on to crosswind, but what’s this? The slip ball has swung to the right! But that would mean I’ve used too much rudder. Surely that can’t be correct – everyone knows pre-war aeroplanes needed lots of rudder for turn coordination. I try again, this time with rather less pedal pressure, but there it is, that slippery little ball is still half-way along its tube. Hmmm, more experimentation is needed, and so I turn again and again, until I establish the minimal rudder displacement required to stay in balance. While turning, I also realise how little I’m moving the stick laterally. Emboldened, I rock it from side to side in greater arcs until I’m rolling with full aileron and the tiniest squeeze of rudder, discovering in the process that it takes barely a single second to roll from sixty degrees of right bank to sixty left. Then and there, 3,000 feet above the airfield and just two minutes after takeoff, I know this is a great aeroplane.
Now for some specifics: at eighty knots control is excellent in all three axes. The Fury’s ailerons, elevator and rudder are all light and very effective, (probably thanks, at least in part, to that efficient gap-sealing I spotted on the walk-round) although none of its controls is quite as light as, say, a Flitzer’s or a Turbulent’s. That gives this slightly heavier airframe the feel of a rather larger one (perhaps like a more responsive Wot, although it’s been more than forty years since I last sampled one of those). Because all three controls require such little force to displace them, I find it hard to assess harmony in numerical terms. Suffice to say that nobody could ever complain about either the physical exertion required or the result of that effort in any axis. There is no discernable lag in starting or stopping motion in any plane, and I thought the roll-rate remarkable given that it only has two ailerons.
Pitch stability is very positive, and yaw stability is good, but as usual, roll stability−although technically positive−is only barely so, making this one agile little aeroplane, and presumably a very good facsimile of its larger, inter-war, fighter forerunner. Levelling off at 3,500 feet and throttling back to 2,300 rpm gives a steady, if rather breezy eighty knots, burning around 23 litres per hour. Reducing power to 2,000 rpm drops the speed to a calmer and more comfortable (and obviously quieter) 65 knots and lowers consumption to around eighteen lph.
Throttling back further reveals the slightest additional buffet at 45 knots, followed by a straight-ahead stall at a mere 42 knots. Surprised that this speed is so low (Jon had suggested 52 and 47 knots) I try again, with the same result and not the slightest suggestion of any wing-drop. Then I remember I have only a quarter tank of fuel, and so we’re significantly lighter than the maximum takeoff mass required for the annual LAA Permit test flight to which Jon’s figures relate.
Emboldened, I add some power and set up a steady 45-degree left turn, gradually easing the stick rearwards until, with a slight shudder, the wings roll level at 56 knots. That’s nice. The same thing happens in a right turn, but this time the rightwards roll increases our bank rather than reducing it. I should really have experimented a bit more to check the slip ball was properly centred, but cognisant of the low fuel level and dwindling daylight (and to be honest, too excited to wait any longer) I run through a quick HASELL check, slide the sensitive trim lever slightly forwards, and point the nose earthwards for some aerobatics.
As soon as the airspeed rises above ninety knots I must start throttling back, confirming Jon’s suspicion that the propeller’s pitch ideally should be coarser. Pressing further forward on the stick while continuing to squeeze off the power batters my head with slipstream and starts my sunglassed eyes watering as we hit almost twenty degrees of nose-down attitude before the ASI’s needle eventually winds up to 110 knots, which I judge sufficient for my first loop.
Gently reducing the forward pressure, I glance left and right to check the wings are symmetrically on the horizon as the nose rears higher and higher. Instinctively opening the throttle again and adding right rudder as we slow, a quick glance into the cockpit shows thirty knots on the clock while we pass the inverted, and I can start pulling again on both throttle and stick as we accelerate downhill for another one.
That done, I ease up again to barrel-roll right, carefully jockeying stick, rudder and throttle to keep in balance with the varying airspeed, power and swirling propwash. A barrel roll left follows, two right quarter-clovers next, and then two to the left. After these eight manoeuvres I stop the flowing sequence to check my height, and we’ve lost exactly 1,000 feet. Considering the biplane drag, that fine-pitched propeller, my unfamiliarity with the aeroplane and my consequent lack of careful airspeed control in favour of carefree flying, that’s actually pretty good. I’m immediately certain that, given the correct propeller and a little practice, and with the increased power below 1,000 feet, it would be possible to fly a flowing display routine of simple manoeuvres like these without losing any height at all.
I would love to fly a few spins, halfCubans and stall turns, because Jon says the Fury spins and recovers nicely and its big rudder’s power allied with this biplane’s compact dimensions forecast excellent yawing ability at minimal speed for the stall turn. But unfortunately it has a lightweight, fine-pitch propeller, a low idle rpm, and no inverted fuel system.
Why on earth should this affect a Fury’s ability to spin, perform half-Cubans or stall turns? Well, a light propeller has a low moment of inertia, making it a poor flywheel and therefore likely to allow the engine to stop at low airspeeds, especially when it idles slowly anyway, and particularly if there is a tiny bit of inadvertent negative G so the engine quits producing power. Oh, and this O-235 doesn’t have an electric starter (although Jon is considering fitting a lightweight one). Also, he’s never tried a diving re-start which would undoubtedly gobble up a lot of height. So, all things considered, and until I know the aeroplane better, I’ve decided to stick with the higher-speed, all-positive-G manoeuvres!
But I’ve just had a further thought. A simple aileron roll doesn’t cause negative G, so again I dive to 110 knots, clamp the rudder pedals neutral, pitch up the nose to twenty degrees above the horizon, check momentarily, and hit full left aileron. Round she twizzles, in the blink of an eye (actually, perhaps three seconds), ending a mere fifteen degrees nose-low. This is the best trick of the lot, so I do it again, this time with less of a pitch-up, and notice I’ve lost no height at all.
So now I throw this sweet little aeroplane into a succession of free-flying ‘busking’ aerobatics: looping and whooping, rolling and rejoicing. Aileron rolls are so easy that even a non-aerobatic pilot could fly them. Pull up, check, roll, stop: what could be simpler? If the nose does drop too low in the second half, simply close the throttle, pin the spinner where it is, keep rolling and all that biplane drag keeps you safely below the 140kt VNE.
Eventually realising that prudence is the better part of exuberance, I select carburettor heat for a few seconds, and then ease back on the power. Slowing to seventy knots, I re-trim rearwards and start gliding earthwards. The VSI now reads 1,600fpm downhill and the propwash’s previous head buffeting is almost gone. Casting around, I assess the visibility as excellent downwards, to both sides and behind. It’s also surprisingly good forwards, because the upper wing is inches above eye level. The only obscured areas are on both sides about ten degrees upwards and ahead downwards, where any low-wing monoplane would also have a blind spot.
Curving into the circuit, I open up to 2,000 rpm and level off at 1,000 feet but leave the carb air hot because that is well below 75 per cent power and the temperature has dropped, so humidity will be increasing significantly. While scanning for traffic, I recall Jon’s advice: “The glide is steep, carry a bit of power on the approach to keep the prop turning, touch down absolutely wings-level or it can be unpredictable, and then pull out the carb heat and switch off the left magneto after touchdown to minimise rpm so you don’t need to use the brakes.”
For my first attempt in the strong wind (it seems to be at least twenty knots, and possibly even 25kt at 1,000 feet) I fly too far downwind and end up with a ‘conventional’ rectangular circuit and straight final approach at seventy knots: five knots more than recommended because of the low-level turbulence and headwind. The throttle is only half an inch forward of its stop, with the engine quietly idling at around 1,500rpm as we sink towards the threshold. Control is excellent in all axes and forward visibility is fine, with the nose well down. As before, the Fury is rock-stable, with all the steadiness of a larger aeroplane. It reminds me very much of a Stampe.
Selecting carb heat to cold passing 200 feet for a likely go-around from this first landing attempt, I level off from the descent at the normal height while ensuring our wings are absolutely level, glad of that trickle of power since the speed still bleeds away pretty quickly. All those hours in my draggy old Fly Baby were useful preparation for this. Raising the nose at just the right rate leads to the stick accelerating backwards with increasing rapidity, but I don’t quite get it far enough aft before the main wheels touch and we bounce back into the air on those surprisingly stiff suspension bungees. One more skip and a waddle, then we settle. That’s enough, so I cautiously lift the tail, carefully open the throttle, squeeze the right rudder pedal and make a touch-and-go.
Now I ‘know where the ground is’, I perform a more assertive curved approach, turning through 180 degrees from late downwind (but a little before abeam the threshold because of the wind) to final in one long, steadily banked turn, again using carb heat all the way. Visibility is now completely unobstructed (which of course is why the tailwheel fighter boys always did things this way) and I see I could easily glide to touch down one third the way along the runway, so I sideslip a little in the last two hundred feet while reselecting carb heat cold to flare over the touchdown zone. This time I judge the hold-off properly, and am rewarded by a smooth, gentle three-pointer.
That will do nicely thank you, so I fully close the throttle. Remembering Jon’s caution that is has a light tail like the Turbulents we used to fly, rather than braking I raise my hand a few inches to the carb heat to pull it out again, and flick off the adjacent No 2 magneto switch. This nicely increases its deceleration. So confident am I in the Fury’s straight-line progress along the runway that I can also squeeze the pins to open the drop-down cockpit sides with my left hand as we roll gently to a halt with the propeller blades flickering rotary-slowly out beyond that gleaming cowling ahead.
Because I knew I would be preoccupied for the takeoff and landing roll assessments I asked observers Jon M-H and Bob Willies (photo-Cub pilot), who tell me I was airborne after a run of around 150 metres, which Jon says is about normal given the strong headwind and prevailing 15°C/1013 ISA conditions. The landing run was a bit longer, at around 300 metres, but operating from the standard 500-metre airstrip should normally provide no problems. Taxying back to the pumps I am able to flick the mag back on and push the carb heat to cold for filtered intake air, although I am prepared to pounce on the mag switches if I have the slightest doubt about stopping or turning. This is far too beautiful an aeroplane to risk damaging.
A lovely creation Indeed, once I’ve shut down I take the time to admire this lovely creation properly. Its fuselage is predominantly a plywood-skinned spruce structure, with stringer-supported, fabric-covered rear decking and gleaming polished aluminium panels between pilot and engine. Ahead of these, the beautiful hand-formed double-curvature cowlings crafted by Steve Moon are held in place with a dozen screws, with a small hinged flap on the right allowing quick access to the dipstick. The slightly staggered wings have Sitka spruce plank spars and internally wire-braced Warren girder ribs forming the authentically thin, 9.75 per cent RAF 38 aerofoil. External bracing is by N-shaped interplane and cabane struts with Brunton’s expensive but superlative stainless steel streamlined wires (most Isaacs Furies have much more draggy unstreamlined braided wires). As previously mentioned, only the upper wings have plain but efficiently gap-sealed differential ailerons. The tail surfaces are similarly generous, gap-sealed, strutbraced, fabric-covered spruce structures.
The undercarriage is also contemporaneous, with rubber bungeecorded centrally-pivoted axles and wire-spoked wheels based on Triumph motorcycle hubs and covered by aluminium shrouds. These have toeoperated differential hydraulic ex-Honda 400 disc brakes and a steerable tailwheel, rather than the original Fury’s (and Isaacs Fury’s) fixed tailskid. The sixty-litre (useable) fuel tank in the forward fuselage has a transparent-covered rotary indicator protruding just above the top decking. The 108hp ex-Robin Lycoming O-235 and five foot Evra propeller give nearly double the thrust of John Isaacs’s original 60hp Mikron-engined prototype while burning just 23 lph in cruise, giving a three-hour safe endurance or just over 200nm range. Lacking an electric starter, the engine is currently hand-swung.
Although there are generous drop-down hatches on both cockpit sides, only the left wing root has a non-slip panel. It’s an easy step up from here and down into the cockpit which is well aft of the wing so there’s no risk of bumping your head. Once ensconced there’s actually plenty of room, and raising the side hatches gives a nice, snug, at-one-with-the-aeroplane feeling. All the controls are exposed and there are only two long floorboards for your feet, so it’s prudent to keep everything except your chart zipped into overall pockets. Apart from the flying controls, there are quadrants for throttle and trim on the left, with the mixture plunger ahead of them. That’s it, and that’s all you need.
The panel carries all the necessary flying instruments – altimeter, ASI, VSI and G meter – although oddly, instead of being in the usual upper left position, the ASI is at top centre, with the slip ball sensibly placed immediately below it and the compass under that. On the right are the tachometer and oil pressure and temperature gauges. In the lower left corner are the aforementioned magneto switches and carb heat knob. This is a sensible, simple layout in a comfortable if minimalist cockpit, and just right for a no-nonsense, pure pleasure aeroplane.
Endorsed by an authority My boyhood hero, Air Commodore GJ Christopher Paul, Chairman of the Air League, President of the Popular Flying Association (now the LAA) and Managing Editor of Air Pictorial magazine said the Hawker Fury was, of his 276 types, ‘the most exciting to fly’ and I can absolutely see why. The Fury was our best, swiftest and most beautiful inter-war interceptor, and this diminutive namesake perfectly emulates those properties of sparkling manoeuvrability and impressive performance that are fundamental to a great fighter.
I don’t think anything else in this world is as joyous as flying open cockpit aerobatics, and this Isaacs Fury is absolutely the aeroplane for that. Better still, its +6g biplane strength and notable power-to-weight ratio combine with sleek and shiny vintage good looks, giving it all the visual appeal of a classic fighter, but at a fraction of the cost.
Did you enjoy this article? There are plenty more flight tests to read: