When people talk about the French SPAD fighter of the First World War, they are normally referring to either the SPAD.VII or -XIII.
Both of these fighters were extremely successful aircraft that served not just as one of the backbones of the French Air Force, but also with many of the various Allied nations.
The SPADs, designed by Louis Béchereau and constantly evolving, remained able to go toe to toe with the best aircraft that the Central Powers fielded. This success is all the more remarkable when you consider where this line of fighters, arguably one of the most successful in the history of military aviation, started.
The SPAD S.A’s.
Now look closely, can you see what’s odd about this aircraft?
Yep, that’s the propellor.
The SPAD S.A’s were an unusual early cul de sac in fighter design, the nacelle fighters.
With aerial combat rapidly developing during the early days of the war, designers were desperately coming up with ideas to produce true fighters. Ultimately that came about with the development of interrupter gear that allowed aircraft to shoot machine guns through their propellor arcs.
But before that equipment became the standard, in 1914 and ’15 there were several other ideas that saw experimentation and some service, but which ultimately proved dead ends.
Probably the best of these was the use of a “pusher” engine. This placed the engine behind the pilot instead of in front.
This gave him, or an observer, both a better view and the ability to use a machine gun against an enemy aircraft. But pusher aircraft had performance issues in comparison to “tractor” aircraft, where the engine was mounted in front of the pilot.
With no effective interrupter gear available to them at the time, Allied designers struggled to figure out the best way to make effective fighter aircraft. And that’s where Béchereau came up with an interesting solution.
If you wanted the performance of a tractor aircraft, but the combat ability of a pusher, well, stick a nacelle out in front of the propellor and put the observer and his gun in it.
To be fair, It is easy to criticize designs like this, but they were developing these under the pressures of a titanic war in a field of engineering that was basically ten years old, so we should cut Béchereau some slack. But I’m sure that many of you out there can see some very immediate problems with this sort of design, even if you don’t have a degree in aeronautics.
The observer in the S.A did have a pretty good field of view and, with a suitable machine gun, could be effective. Of course, you’d have to be a pretty focused individual to ignore the fact that there was a running propellor LITERALLY INCHES FROM YOUR BACK!
In fact, being an observer on an S.A must have been at best an incredibly unpleasant experience, at worst a gruesome death. To prevent the engine from overheating, all that separated the observer from the prop was a thin mesh screen.
This meant that even on a standard flight the noise must have been something like the end of the world occurring. Communication between the pilot and the observer was, understandably, impossible.
The nacelle, which was referred to as the “pulpit” by the British and as the “basket” by the Russians (see what I did with the title?) would also vibrate like a continuous earthquake.
Now, bear in mind, we are talking 1915 here. The materials used in building these aircraft was largely wood and fabric. The nacelle was attached with two hinged struts to the undercarriage, the only way to mount it without impeding the propellor.
This rather weak joint, combined with lightweight materials and harsh and constant vibration led to an unfortunate tendency for the nacelle to just drop off in flight.
If all this wasn’t bad enough, you could combine it with the fact that the slightest mistake or inattention, and the unfortunate crewman was going to get himself maimed or killed. There is at least one report of an observer’s scarf, standard issue for airmen in World War One, snagging in a running S.A propellor, which immediately snapped his neck.
Additionally, crash landings were far from uncommon in First World War aircraft, especially amongst the hordes of inexperienced pilots who were being thrown into service after minimal training. Quite often, these could be walked away from.
But for an observer on an S.A? For them a crash landing would mean getting hit by the running propellor and several hundred pounds of engine – broadly akin to being dropped into a giant blender and crushed at the same time.
This was one of the reasons why the British Royal Flying Corps, who also designed a nacelle fighter – the B.E.9 – decided not to pursue the idea.
The French, however, were made of sterner stuff. They actually put the S.A into service.
Four variants of the type would be built, which all followed the same basic layout. The aircraft were single-bay biplanes that, as stated, had a two-man crew. Generally, the weaponry was a single light machine gun on a flexible mount used by the observer in the front nacelle.
The initial production variant, the S.A.1, of which eleven were built, had a Le Rhône 9C rotary engine that produced 80hp. These were followed up by the first main production variant, the S.A.2 which had changes to the gun mount and some aerodynamic improvements.
It also had a more powerful engine, the Le Rhône 9J, which produced 110hp. This increased the top speed from 135km/h to 140km/h (that’s 84mph to 87mph) as well as improving the aircraft’s ceiling and flight duration. Thirty-five S.A.2’s were built, as well as two S.A.3 trainers, which had trainable guns mounted for both the observer and pilot.
The 9J engine proved troublesome on these aircraft due to overheating, and the main variant built, 59 S.A.4s, returned to using the lower power 9C.
In French service the S.A’s operated from mid-1915 until early 1917 as reconnaissance fighters. They apparently weren’t very popular, as I’m sure you can imagine, and basically were gotten rid of as soon as anything better became available. Most of the aircraft in fact got exported to Imperial Russia, were they saw more service.
This wasn’t due to any great affection in Russia for the type, they were apparently thoroughly disliked, it’s just the Russians didn’t have a lot of options and had to use whatever aircraft they could get their hands on. However, one aerial gunner with the Imperial Russian Air Service would be credited for achieving two kills in the S.A., which seems to be the types greatest fighting achievement.
But though the S.A’s were short in number and length of service, and certainly not lamented with their passing, they actually made a huge contribution to the French war in the air. Though the concept of the nacelle fighter might have been a dead end, a lot of the engineering and construction techniques that the designers at SPAD developed for the aircraft would prove crucial in the success of their later designs.
Recognizing the problems of putting a human in the nacelle to control the gun, SPAD built the S.G. prototype as their next aircraft.
This put a fixed Hotchkiss heavy machine gun with a thousand rounds in the nacelle, effectively making the aircraft a slightly more conventional fighter. The Russians had a similar idea, converting one of the S.A.4’s they received to a similar standard, though they fitted three machine guns, thought to be Colt Browning M1895s.
Though ultimately unsuccessful, the S.G. was pointing the way and this led to the SPAD V – an S.A. without a nacelle and which would go into production as…the SPAD VII.
And so, the legendary SPAD VII and -XIII were based directly on the S.A series – essentially evolutions of the S.A as single seaters with interrupted machine gun armament.
Though we can now look aghast at the S.A’s and their almost complete disregard for crew safety, they deserve to be remembered as the remarkable stepping stones in aircraft development that they actually were – the direct progenitors of some of the most famous and effective fighter aircraft in history.
Not bad for a flying basket.