Flight Test: Beagle Pup B121 Series 2 

The Beagle Pup B121 Series 2 in flight

The Beagle Pup B121 Series 2 - Credit: Keith Wilson

Gorgeous looks and outstanding, sporting handling come hand-in-hand with baffling design complexity and limited load-carrying capacity

Beagle Pup B121 Series 2  engine

Even with 150 O-320 horsepower, the Pup is hardly over-engined. On its original 100hp it must have given a few pilots grey hair... - Credit: Keith Wilson

Was the range open? This was the question that was vexing both Keith and me as we flew towards The Wash, even though we were in separate aeroplanes. As our formation approached the coast, Fenland Aero Club’s Paul Brian checked in with the Marham controller to find out if the danger area was active. She obligingly agreed she could accommodate our request, and the game was afoot! 

The Beagle Pup is practically the epitome of everything that was both right and wrong with the UK aviation industry in the 1960s and 70s. Although I’ve never flown a VC10, in many ways the Pup reminds me of that iconic jetliner, for both were over-engineered and under-priced. In a wonderful dichotomy, they both look better and have far superior handling than their transatlantic competitors, and yet were totally eclipsed by their American counterparts. 

Even the test aircraft’s paint job was vaguely reminiscent of a BOAC VC10, and as owner Phil Parsons and I strolled out to G-AXJI on a lovely June day at Fenland my initial impressions were all positive. Built in 1969,
‘Juliet India’ was the ninetieth B121 Series 2 to roll off the Shoreham production line, and from the tip of the pointed spinner to the top of the sweptback fin, it really is a very attractive aeroplane. However, you should never judge a book by its cover, and as I began the preflight some curious anomalies became apparent. 

For example, as the aircraft was standing on grass, it’s obvious that the wheels (which are all the same size – 5.00 x 5) are rather on the small side. Not ideal for operating in a country with a lot of grass runways. At only 1.4m. the wheelbase is not particularly long, although the track of 2.13m is quite wide. The undercarriage looked reasonably robust, but looks can be deceiving, it’s not as rugged as it looks, and considerably more complex than it needs to be. The mainwheels are fitted with hydraulically-actuated disc brakes. 

Access to the engine bay is excellent. Dzus fasteners secure the cowling, which opens wide on both sides to reveal a very neatly installed 150hp Lycoming O-320. It spins a two-bladed fixed pitch Sensenich propeller. 
The wing is a conventional single-spar, two-cell structure made from light alloy. It features an NACA 63-615 aerofoil, and has about 6° of dihedral and an elegant taper. Intriguingly, the leading edge appears to twist slightly downwards from about mid-span There is a large landing light in the leading edge of the starboard wing, while the remarkably beefy-looking pitot head is suspended below the port. Substantial stall strips are a notable feature of the leading edge near the wing roots (where they serve to ensure the wing stalls progressively from root to tip, reducing the tendency to drop a wing), while the trailing edge consists of slotted ailerons and electrically-actuated slotted flaps. 

Beagle B121 Pup 2 wing

Stiffening ridges in the ‘corrugated’ control and flap skinning are one thing the Pup has in common with US light aircraft: the number of rivets and compound curves in the fuselage panels are things only Beagle thought necessary - Credit: Keith Wilson

Built like a... 
Moving around the aircraft I’d started to notice that the Pup does share several traits with its bigger, twin-engine cousin the 206 Bassett, the most noticeable being the number of rivets. As you’d expect on an all-metal aircraft of stressed-skin construction, there are obviously rivets−but the Pup has lots of rivets. Lots and lots of rivets. In fact, a disproportionately large number of rivets, which hold all the stretch-formed sheets together. The Pup has a considerable amount of double curvature panelling and overlapping skins, which, while probably aerodynamically more efficient and certainly aesthetically more pleasing than most aircraft in this class, made it expensive to produce. 

Commenting at the time on the obviously uneconomic construction techniques, Flight magazine’s reporter wrote ‘the Pup appears to be designed not for production but as a one-off special, in which cost was no object’. This observation proved to be prescient, by November 1969 it was estimated that the production cost per aircraft for the first 150 built was £8,850 (more than twice the retail price!) Even more worryingly, projections indicated that break-even would not occur until 4,000 Pups had been sold. As a further example of Beagle’s complete inability to control costs, although Pups were built at Shoreham, they were painted hundreds of miles away at Rearsby! 

Down at the tail I was intrigued to spot some other aerodynamic add-ons and incongruities. For example, there is a pair of horizontal fuselage strakes just in front of the tailplane roots and a large ventral fin. The fin is quite sharply swept back, while the elevator is both mass balanced and aerodynamically balanced. The constant-chord tailplane is also quite large, probably because the aircraft is relatively short-coupled. The pitch trim tab spans the entire starboard elevator, and I made a note that the trimmer was probably going to be very powerful. The ventral fin incorporates a tail bumper and provision for tail ballast. Interestingly, although it looks like an add-on, it isn’t. It was always in the original design, as Beagle wanted the Pup to have good spin recovery characteristics. 

Access to the cockpit is good, but not brilliant. There’s a well-placed grab handle on top of the fuselage, a step just aft of the trailing edge, and a generously-sized non-slip wing root walkway. The doors open wide (ninety degrees to the frame) and each has a stay that holds it open. Unfortunately, you have to climb down onto the seats, which are quite low. If you’re not as agile as you once were (and I’m not!) it’s not the easiest machine to get in to. The seats are reasonably comfortable, and although the bases are fixed the rake of the seat backs can be adjusted, as can the rudder pedals. The interior used to be a ‘vile red’, Phil has recently had it restored very tastefully in grey leather. 

While researching this article I noted several other flight testers had compared the Pup to a British sports car, and I was beginning to see why. For example, it does have quite a few design and engineering idiosyncrasies, and even fundamental points (such as climbing in and out) could be better. This trend continued into the cockpit, for as with so many aspects of the Pup, it is a curious mixture of good and bad features. 

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I immediately approved of several aspects, such as the big DV (direct vision) panel, four-point harness and elegantly curved control sticks, but was disappointed to note that it only had one throttle. Many years ago, I flew a woefully underpowered 100hp Pup, and it had two throttles−one on the left and one in the middle. Other good facets are that the circuit breakers are directly in front of the P1 and are easy to both see and reach, as is the parking brake. This reminded me of the type of handbrake fitted to the old Ford Zodiac, as you pull it out and then twist it to lock. 

Beagle B121 Pup 2 internal seats

Flying sports car indeed – although our Jaguar-fiend Editor would say more the refurbished plush grey bucket seats are more E Type than MGB - Credit: Keith Wilson

The panel has a military look about it, with the primary flying instruments arranged in the classic RAF T-layout, and delineated by a white line. However, almost a third of the ASI is redundant, as it goes up to 210kt (despite being redlined at 150kt). On the plus side, I liked the old-style turn needle−much better than a modern turn co-ordinator. 

The engine instruments are all grouped in the centre and delineated by a yellow line. They consist of a large tachometer, with fuel pressure and oil pressure directly underneath, then oil, cylinder head and exhaust gas temperatures. (I’d rather have the oil pressure and temperature gauges together.) Extending down from the base of the panel is a small sub-panel which carries a single fuel gauge, some warning lights, an ammeter, starter button, key-operated rotary switch for the mags and five grey toggle switches which are identical in size, shape and colour. I thought the ergonomics of this arrangement very poor.

The first four switches move vertically, and are for the battery, alternator, fuel pump and starter master (of which more later) while the fifth is for the fuel gauge. Yes, there’s only one, despite the aircraft having two tanks. Immediately below the gauge the fifth toggle switch can be selected ‘Left’ or ‘Right’, to show the quantity remaining in that tank. The idea is that you click from one tank to the other, and then add the two values together for total fuel remaining. Yes, you’re right, it is a stupid idea.

Of course, the most sensible thing would have been to simply install a gauge for each tank, as most manufacturers do. After all, you’ve already got a float and a sender in each tank. This obviously flawed fuel system is made worse by the fact that the two tanks are not exactly over large at 54.5 litres each, and the fuel selector is not easy to see, being set into the floor immediately behind the P1’s stick. This makes it difficult for an instructor to even check, let alone reach. I could see how an instructor might think “hmm, plenty of fuel in the right tank”, while the fuel selector was set to left! Just leaving the tank selector on ‘Both’ isn’t a solution either, as the tanks don’t always feed equally, and if you do run one tank completely dry the other doesn’t cross feed. 

Further back is the centre throttle quadrant, which consists of (from left to right), throttle friction, a nice big chunky T-handle throttle, and then the mixture control, which, curiously, is not only the wrong colour but also the wrong shape. It is round and blue, and should be knurled and red. Furthermore, the throttle should be black, not white. Then there’s a large wheel for the elevator trimmer, with the pitch trim indicator next to it and the flap position indicator next to that. The flap selector switch is at the very back of the centre console. Behind this is a box, with a padded cover on top. It’s not deep enough for charts and airfield guides, and would only take your sunglasses and sandwiches. Still, it’s quite a nice elbow rest and anyway, there’s a huge baggage bay behind you because−let’s face it, the Pup’s not really a four-seater−not even close; it’s a 2+2 at best. 

As it has a useful load of only 379kg, it is obvious you cannot fill the tanks, seats and baggage bay. This loading conundrum is quite common in many other four-seaters, but worse in the Pup, for although the power to weight ratio of early C172s is comparable, the Pup’s wing loading is much greater. 

Beagle B121 Pup 2 undercarriage

Notoriously difficult to work on, the Pup's fusleage mounted main undercarriage is nevertheless elegant and – thanks to neat touches like brake lines running under the fairing and flush hubcaps – must minimise drag - Credit: Keith Wilson

Unnecessary complexity 
As we were preparing to start the engine I noticed another anomaly−there is no Ki-Gas primer, the electric fuel pump is used to prime. And while we’re talking about the fuel pump switch, it is exactly the same as the three near it, one of which is the aforementioned Starter Master switch. 

“What’s a Starter Master switch?” Allow me to explain. To start the engine the key-type rotary switch turns on the mags (like most aircraft in this class) and usually a further turn to the right activates the starter. Evidently, this was far too obvious for the boys at Beagle. Instead, you turn on the Starter Master switch and the mags, then press the starter button. Once the engine has fired you release the starter button and turn off the Starter Master switch. Confused? Yeah, me too. It has long been a fundamental precept of light aircraft design that it is imperative to ‘add lightness and simplicity’. I was rapidly reaching the conclusion that the Beagle boys had perversely decided to go against this and add weight and complexity. 

Now, I’m sure that the members of the Beagle Pup & Bulldog Club are already angrily reaching for their keyboards, but for an air test to be objective I must scrutinise the machine being tested objectively. And before someone writes in to point out it was designed in 1968, and that−particularly in the ergonomics department−I should cut its designers some slack, my riposte is this is still some thirteen years later than the Cessna 172, which does have a proper primer, a rotary, key-operated combined mag/starter switch and a fuel gauge for each tank! 

Beagle B121 Pup 2 internal controls

Proper sticks and a 'very RAF' panel distinguish the Pup from its US rivals. The design predates glass screens and modern avionics (and some will no doubt prefer it for that very reason) - Credit: Keith Wilson

The Pup is a very easy aircraft to taxi. The field of view over and either side of the nose is good, the nosewheel steers through the rudder pedals up to 25° either side of neutral, and the brakes are toe-operated hydraulic discs−my favourite arrangement. 

What wind there was appeared to be favouring Fenland’s Runway 36, which has an upslope component. Consequently, I’d already decided to make a rolling takeoff, rather than lining up and stopping, as I anticipated that getting airborne could well be ‘interesting’. The ambient conditions were a density altitude of about ten feet (Fenland is sea level) and less than five knots of wind, more-or-less on the nose. So, we’d be taking off uphill, on grass and in an aircraft with little wheels−not a good combination−and if Juliet India were a 100hp Pup I wouldn’t even entertain the idea. On the upside, I estimated that being only two-up with half fuel and no baggage we were about 165kg below MAUW (maximum all-up weight). 

Acceleration was adequate but not exemplary, so I rotated at 45kt and lifted off at fifty, having used most of the 600m runway (it was quite a hot day). Flaps up and the VSI was soon showing a creditable 1,000fpm as we set off in pursuit of the C172. 

By now many of you are probably thinking that, in the light of my many and frequent criticisms, that I didn’t like the Pup. Wrong! It does have its inadequacies and idiosyncrasies and is massively over-engineered, but with the speed building nicely I soon started to warm to it. Why? In a word; handling! Rock the stick laterally and the power and precision of the ailerons is undeniable. Forgive all its faults, forget all its flaws: this is one fine-handling flying machine. I don’t know if the design team were all given a ride in a Chipmunk and then told “there−that’s what it should handle like,” but whatever they did, they did it right. It’s just so nice to fly. 

Beagle B121 Pup 2 side door

Not only are the doors large but they open wide and - hooray - there's one on each side! - Credit: Keith Wilson

Many plusses
Indeed, as we went ‘feet wet’ over the coast and closed in on the camera ship, the Pup’s many plusses began to show. The handling really is nothing short of superb, being as good as any and better than most. Indeed, I’d say that it is possibly the best handling aircraft that I have ever flown in this class. The ailerons, in particular, are delightful, being crisp, powerful and wonderfully light, with very low breakout forces and minimal ‘stiction’.

They’re so taut you’d think they’re pushrod driven, but in fact they use cables. Perhaps it’s the bottom-hinged Frise ailerons, or maybe it’s the tapered wing, but it really is first-rate in roll response. The elevator is effective and well balanced, and although I’d initially thought that the rudder was a tad on the heavy side I soon got used to it. Overall, the harmony of control is outstanding. The trimmer is, as I’d anticipated, quite powerful and precise. Field of view is good and it was a pleasure (and also very easy in the smooth marine air) to position the Pup for Keith’s camera. So much so that we got the shoot finished in record time. 

Having broken away from the camera ship I began to explore the envelope in greater detail. Slow flight is easy and an examination of the very gentle stall characteristics revealed that at our weight the IAS at the stall was about 48kt flaps up, and around 42 flaps down. The big stall-strips ensure the airflow separates at the roots first, but I did wonder if the slightly drooped leading edge at the tips also contribute to the carefree handling. 

Beagle B121 Pup 2 quadrant levers

Quadrant levers and a manual elevator trim are features we long for in the Pup's US competitors and many modern ultralights – but what went wrong with Beagle’s colour coding? - Credit: Keith Wilson

Aerobatics would’ve been fun, and as the Pup is cleared to +4.4g and -1.76g at the aerobatic weight limit of 794kg and it is approved for stalls, spins, inside loops, half-roll and dive out, half-loop and roll out, barrel rolls, slow rolls, flick rolls and stall turns. Astute readers will have noticed the caveat ‘aerobatic weight limit’- and that it is 79kg below the 873kg MAUW. Although I thought we weighed less than 794, I didn’t know−so we left the aerobatics for another day. (Shame!−Ed.)

So, control is exceptional, but stability is good too. The large fin, big rudder and ventral fin provide plenty of directional stability, and it’s also strongly positive longitudinally. Laterally, it seemed to be slightly positive to the right and neutral to the left. Accelerating out of the last stall for a look at the cruise revealed that 2,450rpm (75%) at 3,000ft gave us a TAS of 118kt, for around 37lit/hr. A more economical power setting of 2,350rpm (65%) gave a TAS of 106kt at the same altitude, while reducing the fuel consumption, to 33lit/hr. Maximum full tanks range in still air is about 350nm. 

Back at Fenland the excellent handling continued into the circuit, with the aircraft nicely speed-stable and surprisingly small changes in pitch trim when the flaps are extended. Full flap (40°) produces plenty of drag. Keith wants me to use Runway 18 as the lighting is more favourable, and as the wind is now non-existent and the circuit empty, I acquiesce. Phil suggests a Vref of 65-70, which seems a bit fast to me, but it’s his aeroplane so I do as he says, and we sail past Keith’s waiting camera without actually touching the ground! It really is a hot, windless day, so for my next attempt I dial it back to 65, and although this time the wheels do touch, its nowhere near the touchdown zone. For the next one, I tell Phil I’d like to use sixty, and not one knot less. The Pup 
is very speed-stable and we cross the hedge with the ASI’s needle nailed to sixty. Success! A smooth touchdown right in front of Keith’s camera. 

Beagle B121 Pup 2 grounded

Good view over the nose is apparent while taxying – and the Pup’s ground handling is very nice too - Credit: Keith Wilson

A kind of flying MGB 
So, what to make of this contradictory machine? Sadly, its irrefutable that the Pup played a pivotal part in the sad story of the decline of the UK aircraft industry, for although initial flight trials went well and flight testers of the day gave the aircraft rave reviews, things were far from satisfactory. The firm was losing a million pounds a year (when a million pounds was a lot of money) and almost as soon as the type entered service operators began reporting several significant faults, such as engine mounts cracking, fuel tanks leaking and doors opening in flight.

Beagle went into liquidation in January 1970, barely three years after the prototype had first flown. About 150 Pups had been built, and just under 130 delivered. Production peaked at around twenty a month and when the business folded there were orders for a further 276 aircraft! Now, you may be wondering why the company folded with orders for over 270 aircraft on its books. The answer is simple: it was selling each aircraft at well below cost! This not only doomed Beagle but all the other UK light aircraft manufacturers as well−after all, how could they possibly compete? 

There is so much about the aircraft that is right, yet so many aspects are simply unsatisfactory. Phil feels that its foibles add to its charm, and I know what he means. Indeed, the comparison with a British sports car is inescapable. Just like an MG roadster, the Pup is not especially comfortable nor particularly fast. Yet it just looks ‘right’, and once you get behind the controls you forget its faults, and just revel in flying one of the best-handling light aircraft ever made.

Beagle B121 Pup 2 in flight

from this angle the relatively large amount of deihedral is apparent – the Pup manages the trick of both being a stable instrument platform and aerobatic... - Credit: Keith Wilson

Beagle B121 Pup Series 2
Dimensions 
Length
    7.06m
Height    2.29m
Wing span    9.45m
Wing area    11.10sq m

Weights and loadings 
Empty weight 
   494kg
Max AUW     862kg
Max Aerobatic AUW    794kg
G limits    +4.4/-1.76
Useful load    368kg
Wing loading     77.9kg/sq m (15.9 lb/sq ft)
Power loading    7.7kg/kw (12.65 lb/hp)
Fuel capacity    110 lit

Performance  
Vne 
   150kt
Cruise    110kt
Stall    49kt
Climb rate    800fpm
Service ceiling    14,700ft
Take off to 50ft    451m
Land over 50ft    430m

Engine 
Lycoming O-320-A2B air-cooled flat-four, producing 150hp (111.85kW) at 2,700rpm and driving a Sensenich metal two-blade fixed pitch propeller  

Manufacturer 
Beagle Aircraft Ltd