Clerget engine assembly

[old man emu]

[facthunter]

Nice aren't they? Nev

 

 

[Marty_d]

What's the difference in terms of efficiency between a rotary and a radial?

 

 

[pmccarthy]

I was surprised at how complex and clever the assembly was. Had previously thought of rotaries as primitive. I believe a Clerget was more sophisticated than a Gnome.

 

 

[old man emu]

What's the difference in terms of efficiency between a rotary and a radial?

In one way, if a radial and rotary engine were compared under the following constraints the efficiency of both engines should be the same.

 

1. The swept volume of the cylinders was the same. (relates to compression ratio)
    
    
   
2. The volume of the combustion chambers was the same (relates to compression ratio)
    
    
   
3. The offset distance of the piston journals was the same (relates to the possible amount of torque that can be produced)
    
    
   
4. The same fuel is used.
    
    
   
5. The fuel/air mixture is the same for both engines.
    
    
   
6. The same style of carburetor is used on both.
    
    
   
7. Combustion gas exhausting is the same. (Same diameter exhaust pipes)
    
    
   

 

 

Compression Ratio: the ratio between the volume of the cylinder and combustion chamber when the piston is at the bottom of its stroke, and the volume of the combustion chamber when the piston is at the top of its stroke

 

The stoichiometric mixture for a gasoline engine is the ideal ratio of air to fuel that burns all fuel with no excess air. The fuel oxidation reaction is: 25 O2 + 2 C8H18 → 16 CO2 + 18 H2O + energy. For gasoline fuel, the stoichiometric air–fuel mixture is about 14.7:1[1] i.e. for every one gram of fuel, 14.7 grams of air are required.

 

By rights, if everything above is the same, then the engines should be equally efficient. However, as soon as torque is determined at the crankshaft, losses due to friction caused by powering attachments (fuel pumps, generators etc) will occur.

 

The difference could be due to the horsepower that an engine produces.

 

Horsepower = Torque x Engine RPM

 

The efficiency of the engines for doing work would depend on how high the engine could rev. We all know about the gyroscopic effect of the spinning rotary engine on an airframe that is free to move in three axes. As a compromise to flight control, the rotary engine has to be limited in its revolution. Therefore, one could say that the rotary engine in this discussion is less efficient than the radial engine for the task we want from an engine.

 

[MEDIA=vimeo]41546699[/MEDIA]

[facthunter]

The main advantage of this type of engine was better cooling A BIG problem with early aero engines. That is achieved by the engine rotating with the prop attached to the engine itself. This comes with a loss called windage. They were not high power but had a lot of torque at low revs. This particular engine is only 110 HP but it only does about 1100 revs. and turns a very large dia prop. They are relatively HIGH displacement engines and are built quite light. They don't need the large counterweights on the crankshaft as ordinary Fixed radials need as the crankshaft does not rotate They are NOT fuel efficient. They were good at getting into the air and climbing quickly due the large props they were capable of turning so were used pretty exclusively on scouts and fighters to get into the air quickly and climb rapidly. They were all built well for the time to good tolerances of good steel. This is a later design The earlier types were nearly all Gnome et Rhone. The problem was with valve springs in the piston crowns which were delicate and hard to get at. They were ALL 4 stroke despite the internal porting . Castor oil was used in great quantities and was all expelled rather than recirculated. The early types were not equipped with a throttle but were controlled with a "Blip" switch giving the characteristic" reerp, reerp" sound on approach and when taxiing. Nev

 

 

[pmccarthy]

I thought none had a throttle. They had air and fuel valves. The Sopwith Snipe, one of the last, still had a blip switch.

 

 

[old man emu]

Clerget 9B

 

A Clerget 9Bf engine is on display at the Powerhouse Museum, Sydney

 

General characteristics

 

• Type: Nine-cylinder air-cooled rotary engine
   
   
  
• Bore: 120 mm (4.72 in)
   
   
  
• Stroke: 9B: 160 mm (6.30 in), 9Bf: 172 mm (6.77 in)
   
   
  
• Displacement: 9B: 16.29 l (994.08 cu in), 9Bf: 17.5 l (1,067.92 cu in)
   
   
  
• Length: 920 mm (36.22 in)
   
   
  
• Diameter: 9B: 1,020 mm (40.15 in), 9Bf: 1,030 mm (40.55 in)
   
   
  
• Dry weight: 173 kg (381 lb)
   
   
  

 

 

 

Performance

 

• Power output: 9B: 96.94 kW (130 hp) at 1,250 rpm, 9Bf: 104.40 kW (140 hp) at 1,250 rpm
   
   
  
• Specific power: 9B: 0.1308 hp/cu in (5.953 kW/l), 9Bf: 0.131 hp/cu in (5.966 kW/l)
   
   
  
• Compression ratio: 9B: 4.56:1, 9Bf: 5.3:1
   
   
  
• Specific fuel consumption: 9B: 0.564 l/kW/hour(0.74 pt/hp/hour), 9Bf: 0.45 l/kW/hour(0.59 pt/hp/hour)
   
   
  
• Oil consumption: 9B: 0.0686 l/kW/hour (0.09 0.11 pt/hp/hour), 9Bf: 0.0838 l/kW/hour (0.11 pt/hp/hour)
   
   
  
• Power-to-weight ratio: 9B: 0.563 kW/kg (0.341 hp/lb), 9Bf: 0.556 kW/kg (0.337 hp/lb
   
   
  

 

 

 

 

[facthunter]

There's no reason to have NO throttle .It's just that the early carburettors were crude and simple, Later Bentley BR2 s and Siemens-Halske were quite modern looking engines . More like conventional radials. The Siemens rotated at 1/2 engine speed. Nothing much used them after the war ended. They were fairly single purpose. Nev

 

 

[Deskpilot]

Ah, a beautiful video with, for a change, really nice music accompany. As an ex bass player myself, I appreciated the simplicity of the engine and the music.