The tragedy of the Whirlwind is that almost everything about the airframe was right and almost everything about the engine was wrong. Petter’s design was aerodynamically clean, structurally advanced, and armed more heavily than any single-seat fighter of 1940. Test pilots liked its handling and its stability as a gun platform. Had it received a mature, high-altitude engine — a Merlin-class powerplant with a proper supercharger for height — it might have been a formidable all-round fighter.

Instead it was tied to the Peregrine, and when that engine was cancelled the Whirlwind was frozen: no development engine meant no development airframe. It is one of the clearest cases in aviation history of a promising design killed not by the enemy but by industrial priorities at home. Figures for its exact performance vary between sources, so treat the numbers here as commonly cited estimates rather than absolutes.

The “what-if” is not just idle nostalgia. The Whirlwind demonstrated ideas — concentrated nose cannon, a clean twin-engine single-seater, long range with heavy hitting power — that the RAF would spend the rest of the war chasing in other aircraft. The Bristol Beaufighter and the de Havilland Mosquito both eventually delivered heavy twin-engine firepower, but they were bigger, two-crew aircraft that arrived later. A matured Whirlwind might have filled the single-seat long-range cannon-fighter niche years earlier. That it did not is down to a decision made in a Rolls-Royce boardroom, not on any airfield or battlefield — which is exactly why the aircraft fascinates historians and enthusiasts to this day.

The Peregrine was a compact, 21-litre V-12 producing roughly 860–885 hp depending on the source and rating. On paper two of them gave the Whirlwind adequate power; in practice the engine was under-developed and its supercharging was optimised for low and medium altitude. Above about 15,000 ft the Whirlwind’s performance fell away, which mattered enormously in 1940–41 when much of the air war was fought high.

Rolls-Royce had finite engineering capacity, and the Merlin — needed for the Spitfire, Hurricane, Lancaster, Mosquito and more — came first, second and third. The Peregrine was quietly dropped, and with it any chance of a better-engined Whirlwind. A proposed re-engining with Merlins (which would have needed a substantially new aircraft, and became the very different Welkin high-altitude fighter) was not pursued for the Whirlwind itself. Exact power and altitude figures vary between references and should be read as estimates.

There was also the matter of the installation itself. Packaging two liquid-cooled V-12s, their radiators, coolant, oil and exhaust into a small fighter is a genuinely hard engineering problem, and Petter’s solution — burying the radiators in the thick wing centre-section between fuselage and engine — was elegant but demanding to build and maintain. Early aircraft suffered cooling and exhaust troubles that took time to resolve, and every hour spent nursing an immature engine was an hour the tiny fleet was not flying. None of these problems were unsolvable; they were the normal teething troubles of an advanced aircraft. What the Whirlwind never got was the time and the engineering investment to solve them — because the engine at the heart of it all had already been condemned.

Pilots generally praised the Whirlwind’s speed at low level, its concentrated firepower and its stability in the aim. The catch was the landing: the aircraft came in fast — its high wing loading and the demands of its Fowler flaps gave it a notably high landing speed — which made it a handful on the short, rough grass airfields of the day and drove up the accident rate. Combined with weak high-altitude performance and a tiny production run, this limited where and how the type could be used, and it settled into the low-level fighter and fighter-bomber roles where it was genuinely effective.

Visibility from the cockpit was good for the era — the pilot sat high under a framed bubble canopy with a clear view forward over the short nose, an advantage for both gunnery and low-level flying. The controls were generally liked, and the aircraft was a steady platform in the dive and the firing pass. Twin engines also brought a genuine safety margin over water: a Whirlwind could, in principle, limp home on one engine from a Channel sortie where a single-engine fighter would have gone into the sea. Against these virtues stood the demanding circuit, the altitude limitation, and the sheer scarcity of aircraft and spares. The overall verdict of most who studied or flew it is consistent: a very good aeroplane asked to fight with one hand tied behind its back by its powerplant.

It is worth being clear about how much of the “difficult” reputation is fair and how much is exaggerated. Much of it traces back to the landing characteristics and to the fact that pilots came to the Whirlwind straight from docile trainers or from single-engine fighters, with little twin time. Once converted, many pilots were enthusiastic about the aircraft and defended it robustly. The Whirlwind was not a widow-maker; it was a demanding thoroughbred that punished carelessness and rewarded skill. Given a mature engine, better altitude performance and enough airframes to build up experience across more squadrons, it is entirely plausible that its reputation would today be that of a formidable early-war heavy fighter rather than a fascinating failure — which is precisely why it remains one of the most debated aircraft of its generation.

Unlike modern warbirds, the Whirlwind has no meaningful operating-cost figure today for one simple reason: no complete example survives and none is airworthy. There is nothing to fuel, insure or maintain, so a cost-per-flight-hour cannot be quoted — we mark it “not applicable” rather than invent a number.

Its original wartime unit cost is likewise not reliably recorded in the sources we trust; production was tiny (about 114 aircraft) and spread over 1940–42, and wartime accounting figures for such a small run are inconsistent. Where you see money attached to the Whirlwind, treat it with caution. What can be said is that the type’s věrný cost was strategic: an advanced airframe wasted because its engine was never funded to maturity.

For comparison and context only — not as a Whirlwind figure — it is worth remembering how the economics of warbirds work today. A surviving, airworthy WWII fighter such as a Spitfire or Mustang typically costs many thousands of pounds per flight hour to operate, once fuel, specialist maintenance, insurance and the amortised cost of a multi-million-pound restoration are counted, which is why flights in original piston fighters are so rare and so expensive. The Whirlwind sits outside even that world: with no airframe to restore, there is simply no operating economy to describe. If you want the experience of flying a genuine fast military aircraft, the realistic modern route is a jet — which is exactly what MiGFlug arranges — rather than any Whirlwind, which exists today only in photographs, film and relics.