You have to love...
..a set of plans that tells you how to build the things you need in order to build the end-product you want!
A German orthopaedic surgeon in Norfolk has spent £70,000 building himself a flyable full-size replica of the Red Baron's Fokker Triplane. Dr Peter Brueggemann built the First World War-era aircraft by hand – even though when he started he couldn't fly, as ITV News reported. The bright red Fokker Dreidecker I (German for " …
Not so surprising. An ex colleague of mine builds the most exquisite clocks (mechanism and case both from scratch). Admiring the work he casually mentions, that other than a very few tools (magnifiers, vices some but not all saw) He had built all the tools he used - not available from the local hardware store! -> for both of them
a set of plans that tells you how to build the things you need in order to build the end-product you want!
It used to be fairly commonplace - I've got some pages from Practical Mechanics from the early twentieth century which tell you how to build the "White Monoplane". It looks like a fun piece of kit to fly :-)
It's only comparatively recently that we've got into the "it's far too difficult for your little noggin" attitude...
Vic.
"It's only comparatively recently that we've got into the "it's far too difficult for your little noggin" attitude..."
Yep. I think electronics and miniaturization have had something to do with that - the best of today's toys are near impossible to construct from scratch.
As the article says: "it's very difficult to fly", as were many of the designs of that era (on both sides).
There has been one fatality (1996) and at least two prangs (2011, 2014) with various replicas. They are very light and directionally unstable so landing in any kind of wind (especially if gusting) is definitely brown trouser time. I wouldn't want to spin one with that tiny tail...
> original rotary (radial?
Rotaries and radials are different. They both have a single throw crank* surrounded by a circle of cylinders and pistons. The radial has the cylinders fixed with the crankshaft rotating while the rotary has a fixed crankshaft with the cylinders and pistons rotating.
While the radial has to push the pistons back and forth and up and down creating bad vibrations, the rotary moves its parts around in smooth circles, it is just that the pistons and cylinders have different centres of rotation.
Fokker used rotaries.
* some radials had two or more banks and thus more throws.
"While the radial has to push the pistons back and forth and up and down creating bad vibrations, the rotary moves its parts around in smooth circles, it is just that the pistons and cylinders have different centres of rotation."
Aren't they mathematically equivalent, it just depends on which you take as the fixed point about which things revolve? (Like Tycho Brahe's Earth-centred astronomy which was just the same as Copernicus's but using the Earth rather than somewhere inside the Sun as being the fixed point).
I seem to recall that one alleged advantage of rotaries was that the force on the valves would tend to prevent a broken valve from dropping into the engine, a big problem in those days. Otherwise, the rotary was like the Wankel - nice in theory, a pig in practice.
> Aren't they mathematically equivalent, it just depends on which you take as the fixed point about which things revolve? (Like Tycho Brahe's Earth-centred astronomy which was just the same as Copernicus's but using the Earth rather than somewhere inside the Sun as being the fixed point).
Not when you calculate the forces involved they aren't, in either case. For example: what would the gravitational attraction have to be to keep the Sun in orbit around the Earth on a daily basis ?
Get, say, a small bicycle wheel and spin it. A rotary runs like two of those with their axes offset. Now get two wheels that are not spinning, have one stationary and shake the other one sideways and up and down 2,000 times a minute. That is what a radial is like.
>I seem to recall that one alleged advantage of rotaries was that the force on the valves would tend to prevent a broken valve from dropping into the engine, a big problem in those days. Otherwise, the rotary was like the Wankel - nice in theory, a pig in practice.
Another advantage of the rotary is that it doesn't need a flywheel to keep it relatively smoothly running because the whole engine acts as a flywheel. This keeps the weight down compared to an inline or a radial.
Wankel's are fine, except the seals wear out too fast. I had one as an auxiliary in a sailboat: light, compact, simple, vibration free, reliable, quite cheap. It only ran about 2,000rpm so the seals were not a problem.
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> It is the rotary that, in my example, is like the sun rotating around the Earth and not vice versa.
I made no comment about whether either of the engines were "like the sun rotating around the Earth [or] vice versa". I was merely pointing out, in the case of Earth-Sun, that your claim of '_mathematical_ equivalence' was incorrect. It may be that the relative motion can be contrived either way but any _mathematical_ calculations will show only one could possibly be correct.
> The rotary is like a large, heavy flywheel rotating at the same speed as a much smaller wheel. Attached to the much smaller wheel are the pistons, which travel around it in a kind of wave motion which accounts for the offset from the flywheel. The pistons thus rotate in a circle as well as going up and down.
No, you are quite wrong. The pistons do _not_ go "up and down". There is no 'wave motion'. There is a fixed centre of rotation of the crankcase (relative to the fuselage) and a fixed centre of rotation of the piston assembly. The latter is offset from the former by the crank and this is called the 'throw'. The pistons rotate at a fixed distance from the crank pin, controlled by the piston rods. The pistons make no motion (relative to the fuselage) other than around in a circle.
It happens that, because the two centres of rotation are offset, that the relative positions of the pistons within the cylinders changes as the two rotate. But neither the pistons nor the cylinders go 'up and down' nor 'left and right', nor 'wave', they only go in a circle at a fixed distance from their fixed centres of rotation.
> As a result the rotational energy is not only due to the big flywheel (the crank, cylinders etc.) but also the rotating masses of the pistons. As they go up and down, the variation in effective radius causes a variation in kinetic energy which manifests itself as a shaking of the whole system in a circumferential direction - exactly the same as with a radial or in-line engine on its crank.
No. Completely WRONG. They do not go 'up and down'. There is _no_ variation in effective radius. All parts are always at the same radius from their actual centre of rotation. There is _NO_ variation in kinetic energy during a rotation (except, of course, when the rpm changes). There is _NO_ "shaking of the whole system in a circumferential direction". That is one major reason why rotaries were used.
> You have been trying to suggest that both engine types have "wheels" of equivalent size and mass. They do not. The radial's single wheel is very much smaller than either of the "wheels" of the rotary.
I made no such suggestion about their size and mass, I was only indicating that the motion of the parts were completely different is response to your assertion that their motion might be "equivalent". It is not equivalent, especially mathematically.
The two wheels in my example that was illustrating the non-equivalence of motion in the radial, were the fixed circle of cylinders and the 'up and down, left and right' moving circle of pistons. I dispute that in two engines (of the same capacity) they would have 'wheels' of cylinders and pistons that were much different. You have obviously misunderstood a simple analogy by not noticing that I said in the case of the radial that the 'wheels' (of cylinders and pistons) were "two wheels that are not spinning", the 'up and down, left and right' are imparted by the crank.
Certainly in both engines the diameter of the circle defined by top of the piston heads is smaller that the diameter defined by the tdc of the cylinders - the difference being the stroke. I made no claims about what size the wheels in my example should be, it was merely to illustrate the actual motion, and the non-equivalence in opposition to what you claimed.
> Radials don't tend to have significant flywheels; the propeller and its boss fulfil this function.
Maybe, but many inline engines do.
> Remember that the energy of a small volume of a rotating component is proportional to radius squared, so the cylinder heads being well out from the hub have a much bigger effect than the relatively small rotating hub of the radial.
I left the discussion about the gyroscopic effects to others who had already dealt with that perfectly adequately.
> Radials don't tend to have significant flywheels; the propeller and its boss fulfil this function.
But they do have rather massive counter-weights on the crankshaft opposite to the throw. This is required because the crank and whole piston assembly will move in one direction while the counter-weight balances this by moving in the other direction. This acts as a flywheel by increasing the rotating mass (and the weight of the engine) but is required to stop the engine shaking itself apart.
> The only thing that rotates is the crankshaft.
Which includes the large counter-weight.
> Therefore the kinetic energy of rotation is very, very much less. But the vibration is exactly the same.
Rotaries don't have any significant vibration.
Rotaries also have much less mass in their cylinders than a radial does because the cooling is much more efficient and requires smaller cooling fins and less wall thickness. The crankcase is also lighter than a radial because it doesn't have to control the stresses that a radial produces. While the rotary does have greater angular momentum, it is not as different as you imply. The rotary is also much lighter than an equivalent radial of the same size, but it is much less efficient in fuel and oil usage.
Aren't they mathematically equivalent, it just depends on which you take as the fixed point about which things revolve
They may be at an armchair theorists level, but the practical problems that each design creates or solves are completely different.
Rotaries were simple to build, had very few moving parts, and were light for the power they produced.
But the problems of connecting fixed fuel tank to a rotating set of cylinders meant the induction system was via the crankshaft . Some engines only had one valve per cylinder
Contrariwise the radial cylinders did not spin and therefore had less efficient cooling. And no chance to put an overhead camshaft on!
All these designs were explored, and which one was best was often down to trivial details of material science. Indeed the jet engine was held back from its initial theoretical design in the 1920s by the simple problem of finding materials and bearings that could take the high RPM and temperatures in the engine.
Indeed heavier than air flight itself is contingent on one simple bit of engineering: A power plant that delivers somewhat more than about 10W/lb (total airframe) weight. (A typical light aircraft of today is around 70-W/lb) That power is needed to essentially offset in rate of climb terms, the rate of sink of the airframe in a glide.
And of course to get up there at all, takes more power than that
"They may be at an armchair theorists level"
I consider myself suitably put down. However, I take issue with several points: rotaries have exactly the same number of moving parts as an equivalent radial. They also are rather restricted in terms of where the exhausts come out. And, as for cooling, as they are rotating at prop speed the cooling air flowing over the cylinders is more or less the same as for a radial.
I don't understand your remark about overhead camshafts; rotaries didn't have them. Their geometry is, after all, the same as a radial. Radials can be fitted with OHCs using a bevel gear, as was done with many single cylinder motorcycles engines and a few twins, it's just rather over-complicated for the benefits.
This is a complicated subject and we all have varying views on it, no need to resort to insults.
The rotary has a much larger mass rotating than the radial, which is not a good thing in an airplane. Tends to make things want to turn when you don't want them too, especially when changing power settings. Some of the high power WWII planes had enough trouble with the mass of the prop when increasing power quickly. Doing that with essentially the entire engine spinning is a bad idea. But that is what they did early on.
It does seem terribly wrong to put a 4 cylinder in a Fokker DR I though.
The DR I replica that my dad flies sometimes in Brampton, Canada at least has the right type of engine in it.
Probably a lot easier with that flat-4 engine that it would have been with the original rotary
Perhaps. The O-320 still generates a load of gyroscopic movement as you manoeuvre...
What it will be is much simpler to get serviced; the Lycoming is quite an old engine, but there are thousands of them in daily use.
Vic.
Rotary. I dont think there were any radials at that time. The early WWI aircraft nearly all used radials or big straight 6s or V8s.
MM I lie. Radials did exist - the Bleriot had a 3 cylinder radial - but the technology of the time favoured rotaries or water cooled inlines and Vs
Radials came into their own in the 1920's and were probably the best type of WWII engine, if for no other reason than aircooling rendered them less vulnerable to battle damage to the radiators.
The DR1 was equipped with an Oberursel Ur.II 9-cylinder rotary engine developing 82 kW (110 hp)
Basically a copy of the Allied Le Rhône rotary units.
A lot of planes from that era were difficult to fly. Supposedly, the Sopwith Camel had a dramatic tendency to oversteer and dive to the right, due to the plane's light weight incorporating a engine.
But then for most of WW1, pilot safety was an afterthought. I remember reading that in the first couple years of the war, many pilots were not issued with parachutes. This was because the generals thought that pilots would bail out at the first sign of combat, rather than risk being hurt.
(Mine is the leather pea-coat with the white silk scarf and goggles)
"many pilots were not issued with parachutes".
They were rather experimental in those years.
Lots on the history in the Wiki. including this and I''ll be damned if Leonardo da Vinci isn't in there too.
https://en.wikipedia.org/wiki/Parachute
"Otto Heinecke, a German airship ground crewman, designed a parachute which the German air service introduced in 1918, becoming the world's first air service to introduce a standard parachute. Although many pilots were saved by these, their efficacy was relatively poor. Out of the first 70 German airmen to bail out, around a third died,[27] including aces such as Oberleutnant Erich Löwenhardt (who fell from 3,600 metres (11,800 ft) after being accidentally rammed by another German aircraft) and Fritz Rumey who tested it in 1918, only to have it fail at a little over 900 m (3,000 ft). These fatalities were mostly due to the chute or ripcord becoming entangled in the airframe of their spinning aircraft or because of harness failure, a problem fixed in later versions.
The French, British, American and Italian air services later based their first parachute designs on the Heinecke parachute to varying extents."
Regarding "the generals thought that pilots would bail out at the first sign of combat" I have a slight feeling it could be one of "those" stories, do you have a reliable link about that claim.
I don't know about a link but if you can find the book "No Parachute" by Arthur Gould Lee (later Air Vice Marshal Sir Arthur), which is a contemporary first-hand account, the failure of the RAC to recognise the need for parachutes is mentioned throughout.
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Your coat is indeed required. Orthopaedics is muscles and bones. Orthodontics is teeth. Lucky he wasn't one of those Paedophilic surgeons they have in Portsmouth (https://goo.gl/8zunyy)
All of that said, we are all actually Xenophobes now it seems so he's finished his plane just in time to fly it back to Germany where he belongs! He is after all a prime example of yet another low skilled immigrant nicking our jobs and sucking our welfare system dry.
>Orthopaedics is muscles and bones. Orthodontics is teeth. Lucky he wasn't one of those Paedophilic surgeons they have in Portsmouth (https://goo.gl/8zunyy)
They choose the titles to baffle the witless so it's bound to result in the occasional bodily harm - 'Tooth Straightener', 'Bone Specialist', 'Children's Doctor' don't quite strike the right level of awe I suppose...
I remember attending a talk that Cole Palen (RIP), of Old Rhinebeck Aerodrome fame, gave 30 years ago, or so. He stated that one of the reasons that the Fokker Dr.1 was so successful was that it was aerodynamically unstable. It required constant input from the pilot to keep it flying straight and level. Absent that continuous input, it would tend to spiral out of control. But, as a result, it was also very adept at turning quickly, much more so than some of the Allied fighters of the time.
http://oldrhinebeck.org/
Also, as of that time, there had been several reproductions of Fokker Dr.1s built, but all of them had lengthened the fuselage, in order to increase aerodynamic stability. From the article, it appears that this reproduction may be original with respect to the length. If that's the case, then I wish the pilot well.
Plus, the Germans had mastered the art of the interrupter for the machine guns, so that they could fire through the propeller arc, without shredding the propeller. That allowed the guns to be mounted so that the pilot could sight down them directly, rather than having them offset, as the Allies were required to do.
https://en.wikipedia.org/wiki/Synchronization_gear#Fokker.27s_Synchronizer_and_other_German_gears
As for the Lycoming four cylinder engine, that's quite a deviation from the original design, which used an Oberursel Ur.II 9 cylinder rotary engine. The rotary engines contributed, somewhat, to the handling problems of the original planes, since the heavy mass of the engine, spinning as it did, created a rather tremendous gyroscopic effect. As such, planes with rotary engines tended to turn and dive in one direction much better than the other direction, and exceptional pilots tended to recognize this, and make predictions on which way an opposing pilot would turn while in a dog-fight.
Of course, rotary engines presented a BUNCH of rather serious problems. One was that they were two stroke engines, with the oil being mixed in with the gasoline. The throttle was typically set in a fixed position, and power was controlled by controlling how many cylinders fired on each revolution of the engine. In order to avoid fouling the spark-plugs, Castor Oil was frequently used. Unfortunately, the exhaust stream of these engines tended to direct a lot of the exhaust gases, which contained a fair amount of the unburned Castor Oil, back into the pilot's face. Consuming Castor Oil has a certain effect on the human digestive system. Not all emergency landings were due to mechanical problems with the plane!
Even with the lubrication system, the lifetime of a typical rotary engine was approximately 25 hours between rebuilds. OUCH!
Maybe that Lycoming 4 cylinder engine isn't such a bad idea.
Dave
P.S. I'll get my coat. It's the one with the roll of toilet tissue in the pocket.
Some years ago, a US Navy "Top Gun" pilot convinced Cole Palin to let him fly one of Palin's DR-1 replicas. Which he crashed shortly after take-off. He survived without injury, but the plane was a total loss. You can still see the pile of wreckage, preserved in one of the museum buildings at the Old Rhinebeck Aerodrome.
Interesting post, but AFAIK rotary engines weren't two strokes. Their problem was the difficulty of making an oiling system for an engine that goes round while the crankcase stays still, meaning they used the same kind of oiling as a basic two-stroke: total loss fuel/oil mix. But they were 4 stroke.
A two stroke rotary wouldn't work unless it had a compressor to provide the scavenge, since all the cylinders shared a single crankcase - two strokes need an external compressor as on many marine engines, or they need a sealed crankcase for every cylinder.
Of course being a 4 stroke added to the problems because the valve gear was experiencing a force which from its point of view was trying to pull it outwards.Lubrication, therefore, was almost by accident. 25 hours between rebuilds, though, wasn't that bad compared to the expected service life of as WW1 military pilot.
"That allowed the guns to be mounted so that the pilot could sight down them directly, rather than having them offset, as the Allies were required to do."
IIRC initial attempts by the British to achieve the same effect - involved metal plates on the propeller to deflect any of their unsynchronised bullets that were on a collision course.
Actually the initial experiments with this were done by Roland Garros, a Frenchman. He assisted with work already underway on a deflector system by Saulnier, one of the principals in the Morane-Saulnier aircraft company. In December 1914 Garros visited them, and in April 1915 Garros achieved the first shoot-down of another aircraft by firing through the propeller arc. They used metal wedges attached to the propellor to deflect bullets.
Garros himself was shot down, or possibly had an engine failure and he landed behind the German lines on 18 April 1915 and was captured. His aircraft was also captured but probably provided little new information as Fokker had been working on an interrupter mechanism for a number of months by then, and introduced it shortly afterwards on the E1 monoplane. Garros actually escaped in early 1918 and made it back to France where he rejoined the army and flew again. He claimed 2 further victories before being shot down and killed in October 1918.
I'm not sure that the British actually flew with deflector wedges. In the end everyone basically developed their own version of an interrupter or synchronisation system.
> One was that they were two stroke engines, with the oil being mixed in with the gasoline.
Most rotary engines used in WWI had a four stroke cycle, which is why they always had an odd number of cylinders. As they rotated past top dead centre (or so) each alternate cylinders was fired. Even with automatic inlet valves this worked because the expansion stroke kept the valve closed. They always had mechanical exhaust valves (which in some models were left open for part of the intake stroke to take in air).
The oil was mixed in with the petrol but this was required because the intake was done via the crank shaft and the crank case, this being the only link between the carburettor and the cylinders, and this oil was all that was available to the big and little ends and piston walls.
Two strokes usually rely on the piston downstroke reducing the crankcase volume and thus pushing the new charge into the cylinder. This only works where each cylinder's crankcase is separated (or on a single cylinder engine), or there is another mechanism such as a stepped piston or a supercharger. A rotary's crankcase had an almost constant volume.
Pith stability can always be achieved with a small short tail by making the nose heavier.
Up to the point at which the aircraft is essentially tailless.
Stability is achieved by the simple expedient of arranging longitudinal dihedral to be such that any increase in speed forces the nose up: In a dive, the nose is forced up, as the aircraft pitches up, it slows and the nose is pulled down by noseweight.
The key is that the aircraft CG should be ahead of the integrated effect of the surface area of all the aerofoils
A century after its foundation, the Fokker company still manufactures components for airplanes like the JSF, whilst the government is buying a new Boeing (presumably named Air Farce One ('Kluchtmacht' in Dutch)).
Remember that the counry was neutral in WW I, so Fokker made much money in Germany.
"Remember that the country was neutral in WW I, so Fokker made much money in Germany."
Anthony Fokker was Dutch but moved to Germany. He then moved back to the Netherlands and the Wiki has this to tell about that.
"Return to the Netherlands
In 1919, Fokker, owing large sums in back taxes (including 14,250,000 marks of income-tax),[5] returned to the Netherlands and founded a new company near Amsterdam".
The Netherlands, neutral or not had nothing to do with Fokker in WW I.
Well they built a glider for an escape from Colditz during WWII. It was never flown (quite possibly to the relief of the escape team), but I was given a scale model balsa & tissue model as a child and mine flew. I seem to remember it ended up in the jaws of our Labrador who had observed us laughing ti from the top window in the house and cunningly waited outside, biding his time.
I have read various accounts of aging aviators being given a chance to fly one of their old aircraft types again. These are generally war veterans, who had to be really really good with those planes to have survived. In almost every case, they comment on how hard to fly the Old Bird was. Warplanes often were designed in a hurry, and frequently sent into battle with some quirks that could get the unwary pilot killed. Tendencies to spin, that sort of thing.
In other words, an old combat veteran of the DR1 (yeah we'd need a time machine) would probably have a helluva time trying to keep it under control. I can't imagine how a new pilot (trained on stable modern civilian planes) will fly this for long without some kind of crash. I hope I'm wrong, for his sake and the lovely replica's.
I think having a nice modern Lycoming flat-four engine will go a very long way to make the thing more controllable. Apart from the great reduction in gyroscopic effects (precession and the tendency to rotate the entire aircraft backward when the throttle is opened) there's the fact that the engine will have a smooth throttle control instead of hit and miss. Luxury such as the Red Baron could only have dreamed of.
There's a nice example of the gyroscopic effects of a rotary in this clip of a ground run of a Sopwith Camel with a Gnome rotary - the aircraft is clearly pretty keen on flipping over when the guy hits the blip switch.
A handful at 10,000 feet I'd imagine, no wonder pilots said the Camel offered a choice "between a Red Cross, a wooden cross or a Victoria cross".
https://youtu.be/u3DXEsC4Pq8
After the turn of the century
In the clear blue skies over Germany
Came a roar and a thunder men had never heard
Like the scream and the sound of a big war bird
Up in the sky, a man in a plane
Baron von Richthofen was his name
Eighty men tried, and eighty men died
Now they're buried together on the countryside
"the relatively primitive rotary engines of the day were only capable of around 110hp"
If around 1917, allied warplanes had more powerful rotary engines (130 HP for the Camel), they were also fitted with V-shaped engines like the Hispano-Suiza 8Be (220 HP). Germans were also using inline engines, like the Mercedes D.III (160 HP)
You read that right... a vintage 30MB HDD. And a 286-era IBM PC.
You needed a low-level formatting tool to get it pre-formatted, even before DOS could be installed on it, things I'd totally forgotten.
Nostalgia and rosy glasses... dang it took some serious work even before he could install an OS on that thing.
And yes, being a surgeon would have helped on that vintage IBM PC assembly as well.