sopwith camel

[fitzee]

What exactly made the Camel so tricky to fly?

The "Pup" was such a successful design

and both aircraft look so similar, any ideas

cheers

Fitzee

[robmoff]

With all of the heavy componente grouped together up-front [engine two guns, pilot fuel and oil tanks] the control response of the camel was very sharp. The gyroscopic progresion of the heavy engine caused the nose to rise in a left turn and fall in a right turn; EITHER could lead to a sudden spin.

But the camel is still considered to be a success, isn't it?

[centurion]

The big Bentley rotary engines on the Camels were very much more powerful than the engines on the Pup which greatly increased the torque (the tendency for the aircraft to try spin in the opposite direction to the engine) exacerbating the effects described above (German Siemens fighters had a similar problem which was not solved by having contra rotating double rotaries)

[Adrian Roberts]

The grouping together of heavy components was deliberate in order to achieve high manoueverablity, aided by the short-span wings and short fuselage. (Have you seen a Pitts Special doing aerobatics? Similar design but not a rotary engine; roll-rate of 360 degrees a second). Fighters have always been designed for neutral stability in roll i.e. they do not return to the horizontal; the Camel came close to having negative stability. The pilot had to fly it all the time, i.e he could not take his hands off the controls and expect it to remain on course. (Was there any provision for trimming? Some WW1 types such as the F2B had an adjustable tailplane?). The Morane was even worse than the Camel but not intentionally; a Eurofighter Typhoon is deliberately unstable but has a computer, several in fact, which helps somewhat.

(German Siemens fighters had a similar problem which was not solved by having contra rotating double rotaries)

Centurion - do you have any more on this, e.g. diagrams? My information is that the Siemens DIII and DIV had Siemens-Halske 11-cylinder rotaries, but it doesn't say that there was anything unusual about them. Surely a two-row contra-rotating rotary would be immensely complicated, and heavy, but if it did work then surely it would cancel out the torque (except for that of the propeller)

Adrian

[Starlight]

It would have been difficult for a pilot fresh out of training when confronted with an aircraft (viz. the Camel) that was very different to fly, especially when performing turns. In the Camel to make a steep left turn you needed to apply full left rudder and have the control stick to the left and fairly well back whereas for a steep right turn you had to move the control stick to the right and fully back but still apply a moderate degree of LEFT rudder. Any novice pilot who forgot this and applied any degree of right rudder by mistake in a tight right turn would be in trouble as the Camel would instantly roll to the right, leading either to a spin or a spiral dive unless corrected.

[centurion]

Adrian

The Siemens Halske Sh III was geared so that the crankshaft rotated in one direction at 900rpm and the crankcase and cylinders rotated in the opposite direction at 900 rpm (in conventional rotaries the crankshft does not rotate only the case and cylinders to which the prop is attached.) In theory this should have eliminated the torque but for some reason (apparently never understood at the time) it did not. However it did compensate for the gyroscopic reaction.

The achilles heel(s) of these engines was (were)

The increased number of cylinders made them run hot and the closeness of the same constricted air flow

The relatively slow speed of rotation further reduced airflow

There was a shortage of suitable lubricatiing oil (castor oil) as a result of the RN blockade and substitutes were inadequate so engine fires, siezures and disintegtrations were not uncommon.

Herman Goring didn't like the Siemens fighters (he found them difficult to fly - goodness knows how he'd have managed in a Camel) and campaigned against them blaming the engine design (even though Udet championed them.

[fitzee]

I recently visited an aeronautical collection in Canada and took some time to take in the elegance and beauty of the "Camel"

This quote initially sparked my question

"Hundreds died in it's cockpit before they even encountered the enemy. Some could never master just when or how to lean off the rich mixture after take off,which was the kind of thing it should have been possible to teach without duel controls but for some reason it caused endless fatal engine cuts. Many trainee pilots died because they simply could not handle such a highly strung, lopsided racehorse, which became doubly dangerous because it's reputation put fear into the raw pupil and prevented cool judgement.

Just why the Camel was so tricky is something I have never understood, and I am confirmed in my puzzlement by the inability of articulate men who flew the Camel to explain it either

Somewhere I read it took the Camel the same time to turn 270 degrees to the right as to turn 90 degrees to the left so Camel pilots never tended to turn left. I do not believe this and it certainly cannot be explained by any logical theory"

Perhaps the author was unaware of the effects of gyroscopic torque

[ian turner]

Read 'Winged Victory' by Victor Yeates - he was a Camel pilot. He describes its strange handling, but concluded that it made an ideal fighter, since indeed it required constant control to keep level, rather than remain a stable platform by default.

Taking a hand off the stick let the aircraft do unpredictable things - ideal if being chased by a German who would be equally surprised by the Camel's sudden change of attitude and direction!

Ian

[Adrian Roberts]

The Siemens Halske Sh III was geared so that the crankshaft rotated in one direction at 900rpm and the crankcase and cylinders rotated in the opposite direction at 900 rpm (in conventional rotaries the crankshft does not rotate only the case and cylinders to which the prop is attached.) In theory this should have eliminated the torque but for some reason (apparently never understood at the time) it did not. However it did compensate for the gyroscopic reaction.

Thanks for this. The crankshaft would not have weighed the same as the cylinders and crankcase, so it would only have cancelled out some of the torque.

The rotary engine was a simple unit once the design work was done, but the mathematics of the design - the balancing, the design of the conrods to achieve the optimum cylinder position at each point in the cycle - would have taken an absolute genius to work out; amazing considering that the internal combustion engine had been around not much more than twenty years when the first rotary was designed. And to incorporate a rotating crankshaft must have been even more fiendishly complicated.

On this level, it would be quite wrong to think of the rotary as primitive; but of course it would have been impossible to produce a rotating cylinder design large enough to produce the horsepower that Vee-engines were producing by 1919, and the lubrication was only ever achieved by a crude total loss system.

[centurion]

I know more about turbo jets than rotaries but understand that there is a physical limit as to the amount of fuel and air you can get into a rotary which limits its size and power. The big Bentleys that powered some Camels and the Snipe (and Salamander) were near the top limit. Hence the interest in radials such as the mis designed Dragonfly engine which were intended for future Sopwith fighters (including a version of the Snipe).

I don't know the weights of Seimens engine components but I've a feeling that aluminium alloys were used where possible whilst the crankshaft was cast and then machined out of steel. Certainly it was Seimens' calculation that the torque would be eliminated

[MikeW]

Most of you are confusing Torque with Gyroscopic Precession. If you hold a heavy spinning gyroscope and try to turn it, it will snap round in one direction, but will fight you all the way if you attempt to go the other way. The large rotary engine was a very effective gyroscope.

The Camel would turn right very quickly but didn't want to go left at all.

To make matters worse, the aircraft was rigged "tail heavy". Ie. a rearwards centre of gravity. If the hands were taken off the controls or the engine stopped it would try to stand on its tail.

Today we would call it "unstable" and probably insist that there be a computer between the control stick and and the control surfaces!

Novice pilots that found making the fuel/air mixture adjustment difficult when leaving the ground invariably stalled and spun in with a high liklihood of killing themselves.

[centurion]

Rotary engined aircraft suffered from both gyroscopic and torque effects as I described earlier. Torque is the tendency for the airframe to want to rotate in the opposite direction as the engine and propellor. (Its the reason why single blade set helicopters have a tail rotor). The Camel suffered from both effects whilst the Siements with its counter rotating engine didn't have the gyro effect ro much but did suffer from torque.

[AlfaMale]

I've never actually understood the design rationale behind the rotary engine (although I'm probably just missing something) - surely it's a colossal waste of power to spin an engine and propellor around rather than just the propellor? Or was it simply so difficult to cool an air-cooled engine at the time that the wastage was justified by being able to spin the cylinders through the slip-stream? I still don't understand why a radial with the cylinders jutting out into the slipstream (like the later Bristol Bulldog) couldn't be used. There seem to have been so many disadvantages to them that I assume that there must have been at least some real advantages to justify the design ... ?

[centurion]

AlfaMale

The power/weight ratio was much better than the technology of the day could manage with in line liquid cooled engines. No big heavy crank case, no sump, no cooling system. The early radials (such as those developed in Russia ) were water cooled with the need for drag inducing radiators and the later air cooled ones in WW1 (such as the Dragonfly series) simply didn't work despite the vast sums of money poured into their development. It wasn't until post war that effective air cooled radials became available (such as the Jupiter seies) and even then the power weight ratio wasn't as good as the rotary but they could greatly exceed the overall power possible out of a rotary which peaks at about 220/250 hp. A radial engine always has a drag problem (which is why early WW2 Italian fighters were so slow but became v good fighters when reengined with German inline engines). The problem can be overcome with clever airframe design (as the Japanese proved) but its a lot more effort.

Sir Henry Royce was contemptous of the rotary and when ordered to gear up to produce licence built French rotaries he instead developed the RR Falcon and Eagle engines probably the best aero engines of WW1 (the Whitehall mandarins punished him by refusing him a licence to built expansion factories and turning instead to the Pulma for the Dh9 a truely inspired decisoon I dont think).

I got taught all of this in my first days as a RR graduate apprentice (very relevant for someone who worked with computers and on the RB211 turbo fan series) and somewhere I still have the technical details as to why the rotary had a superior power weight ratio at lower horse powers - I'll try and dig it out.

In WW1 the rotary was prefered for night fighters as it didn't need a warm up period and for British ground attack as it didn't have a cooling system vunerable to ground fire.

[Adrian Roberts]

To make matters worse, the aircraft was rigged "tail heavy". Ie. a rearwards centre of gravity. If the hands were taken off the controls or the engine stopped it would try to stand on its tail.

Any idea why this was? Surely even by then, aircraft designers would have realised that it is safer for an aeroplane to be nose-heavy to reduce the risk of stalling, as virtually all aeroplanes have been since. I seem to remember that some other WW1 types were also tail heavy, such as the Thomas-Morse (American type, of similar concept to the Camel) and I think also the Spads (a very different concept).

Was it simply that if all the main components were grouped towards the nose, the only way of getting enough authority from the tail surfaces was to make the tail long enough to give them sufficient leverage? In 1930's lightweight radial types, they managed to enable a short rear fuselage by providing very large tail surfaces (the Polikarpov I-16 for instance).

Or was there another reason altogther, or was it simply a mistake?

Adrian

[centurion]

A lot of problems appear to be associated with the 130 hp Le Clerget engines both in terms of adjusting the fuel are mix after take off and in power falling off after flying for a while. (There were also some synchronisation problems) There are a number of complaints /reports to this effect including one from a Lt Tizzard - later become something of a boffin. Indeed Trenchard began asking for the le Clerget to be phased out and replaces by Le Rhones even though there were 20hp less powerful. The Bently engined version was reported to be far superior.

Tail heavyness seems to have been a constructional problem rather than one of rigging - specifically those built by Ruston against whom there are also a number of reports/complaints. Camels built by other constructors seem to have been adjudged ok.

[AlfaMale]

AlfaMale

The power/weight ratio was much better than the technology of the day could manage with in line liquid cooled engines.

Thanks for this Centurion - I had assumed that there had to be some inate advantage to such a bizarre design but couldn't for the life of me figure out what it was!

Alfa

[per ardua per mare per terram]

Also bear in mind that the instructors were also on a steep learning curve themselves. The numbers who had been flying even 3 years by the time the Camel was introduced were minimal and they had been instructing for even less time. They first had to learn the radically different characteristics of the plane and then communicate these to their pupils.

At the most basic, the Camel was a single seater and there was no one else around to correct the mistakes and it bit back when the pilots got it wrong. Even now it can take time for pilots to adapt to new aircraft: for the most part modern pilots have more flying hours before they have to make those adaptations and have the advantages of simulators and support way beyond the WWI era.

[ian turner]

Novice pilots were prone to the error of trying to return to the landing strip if things went wrong shortly after takeoff. As a result with no (or a lack of sufficient) power and a lack of height, attempting a turn proved to be an unforgiving manoeuvre in a Camel. The result a fatal spin.

Ian

[centurion]

There seems to have been no real attempt to select trainers who where good at training, especially in advanced training situations. Sometimes the person who is brilliant at doing a particular thing is sometimes the very worst at explaining it to others and coaching them. I have the mpression that it was a case of "you've done your stint at the front and are getting weary now go off and teach others how to do it before I have to right a letter to your next of kin"

Does any one know of any training for trainers that was available at the time?

[Dolphin]

Does any one know of any training for trainers that was available at the time?

Centurion

You might like to hunt out a copy of Dennis Winter's The First of the Few ISBN 0 7139 1278 2, which gives an outline of the RFC training system that was revolutionised by Major R R Smith-Barry in late 1917. In essence, the Smith-Barry system included the establishment of the School of Special Flying at Gosport where potential instructors were taught how to fly properly (eliminating various bad habits that they'd acquired through previous poor instruction) and, more importantly, taught how to instruct. It was the beginning of the method of flying training used by the world's civil and military instructors to this day.

The Smith-Barry system is dealt with in lots of other books, including Steel & Hart's Tumult in the Clouds ISBN 0 340 63 846 X, Barker's The Royal Flying Corps in World War I ISBN 1 84119 470 0, and, of course, Volume V of H A Jones' The War in the Air.

Cheers

Gareth