Questions on the S.E.5a (instruments, structure and operation)

[istari6]

After many hours in WWII (BoS, BoM, BoK, BoBp), I'm beginning my dive into my first Flying Circus aircraft: the S.E.5a.

 

Despite searching on the web and checking all forum posts here, I can't find answers to the following questions.  Appreciate any sharing of your knowledge!

 

1. Pressure Gauge - how do you use the pressure gauge in the upper left of the cockpit?  Is that a way of correcting the "indicated" altitude on the lower right?

 

2. Expansion Tank - located in the center of the upper wing.  What does this do?  

 

3. Overcooling - what happens when an aircraft engine gets too cold?  I generally leave the radiators open to 100% on the S.E.5a after boiling coolant on my first flight.  But received a warning I'd overcooled the engine during a patrol at 10,000 ft.  Not sure what effect that has.

 

4. Mixture - I understand I need to manually lean the mixture as I climb in altitude.  But why does having mixture too high cause loss of power?  I'd think that it would just waste fuel, but it seems to actively drop RPMs in the S.E.5a if not at the optimal setting.  

 

5. Pulley Windows (?) - what are the triangular "windows" on the tips of the wings and elevators?  Was that for the ground personnel to check the cables, pulleys and other "drivers" for the flight surfaces?  The equivalent of an access hatch in a WWII aluminum airframe?  Also, are those glass? There was no plastic yet in aircraft, right?

Edited August 17, 2020 by istari6

[unreasonable]

In outline: 

 

1) It shows the air pressure in the fuel system needed to ensure fuel flow. With the engine off it is at zero - start [press E] and it automatically rises. In the real plane it has to be pumped by hand. Nothing to do with the altimeter. I doubt it has much game function. 

 

 You can adjust the altimeter - it is showing height above SL by default, if you want height above airfield press LAlt-A (IIRC) it is a toggle, you can see the circle move so that the pointer is at zero.

 

2) This is part of the cooling system - hot water vapour will go into it and condense, then run back down.

 

3) They run rough, lose power and eventually may stop.  So monitor the engine temperature.

 

4) Too rich means not enough air to burn all the fuel, if you have far too rich you can cut a real engine out altogether. I will leave the precise mechanisms to the engine experts - I just think of it as the excess fuel "getting in the way" of the airflow and ignition system.  

 

5) Yes - that is what they are for. I think glass, but not sure. Not plastic, but there are other possibilities. 

[J2_Bidu]

Keep the engine at around 80 C. Close the radiator in a dive (but remember to reopen! easy to forget in a fight). A low mixture also warms the engine, which is relevant for planes with mixture control and no radiator.

Edited August 17, 2020 by J2_Bidu

[istari6]

14 hours ago, unreasonable said:

1) It shows the air pressure in the fuel system needed to ensure fuel flow. With the engine off it is at zero - start [press E] and it automatically rises. In the real plane it has to be pumped by hand. Nothing to do with the altimeter. I doubt it has much game function. 

 

Ah, thanks!  So these WWI fighters didn't have booster pumps or any other way of energizing the fuel line, right?  The pilot pumped the pressure by hand until fuel was flowing, then the engine kept it flowing from there?

 

14 hours ago, unreasonable said:

2) This is part of the cooling system - hot water vapour will go into it and condense, then run back down.

 

Thanks.  

 

14 hours ago, unreasonable said:

3) They run rough, lose power and eventually may stop.  So monitor the engine temperature.

 

Doing a little further research, it seems that the issue with engine overcooling is mostly around the oil.  Apparently, if the oil gets too cold, it loses viscosity, which can reduce engine life or in worst case, cause engine damage if the engine is suddenly revved to full power when totally cold.  

 

14 hours ago, unreasonable said:

4) Too rich means not enough air to burn all the fuel, if you have far too rich you can cut a real engine out altogether. I will leave the precise mechanisms to the engine experts - I just think of it as the excess fuel "getting in the way" of the airflow and ignition system.  

 

Aha.  So it's not just that the fuel is wasted, it's that there's insufficient O2 to get full burn on the baseline amount of fuel that's there (before the excess is counted).  Thus the drop in engine power.  Thanks.

 

14 hours ago, unreasonable said:

5) Yes - that is what they are for. I think glass, but not sure. Not plastic, but there are other possibilities.

 

What else could they use in WWI for a transparent window besides glass?  I know this has nothing to do with the game per se, I just love learning about the actual aircraft from this period.

 

7 hours ago, J2_Bidu said:

Keep the engine at around 80 C. Close the radiator in a dive (but remember to reopen! easy to forget in a fight). A low mixture also warms the engine, which is relevant for planes with mixture control and no radiator.

 

So low mixture = run hot, high mixture = helps cool engine, at cost of some power?

[J2_Bidu]

5 minutes ago, istari6 said:

So low mixture = run hot, high mixture = helps cool engine, at cost of some power?

 

I know lean (low) mixture makes the engine hotter. Don't know the effect of rich (high) mixture past the optimal point.

 

To dive the DR1 (which has no radiator), I might both reduce the throttle and lean the mixture, for instance. Only one one single case have I ever flown a plane with lean mixture deliberately for heat while in normal flying, and that was on an extremely cold mission (multiplayer event - most likely the Bloody April event) where the plane in question (Sopwith Strutter IIRC) would freeze to death otherwise.

[unreasonable]

58 minutes ago, istari6 said:

 

What else could they use in WWI for a transparent window besides glass?  I know this has nothing to do with the game per se, I just love learning about the actual aircraft from this period.

 

So do I - this is as much an interactive history and engineering lesson as a game.  Possibly sheet mica? You can get extremely thin sheets and therefore very light. I do not know what what actually used, I would guess glass. 

[76SQN-FatherTed]

2 hours ago, unreasonable said:

 

So do I - this is as much an interactive history and engineering lesson as a game.  Possibly sheet mica? You can get extremely thin sheets and therefore very light. I do not know what what actually used, I would guess glass. 

Perhaps celluloid or oiled silk?

[HagarTheHorrible]

Yes, Celluloid.  It was even suggested to make a whole aircraft (skin) out of it, to make it invisible, didn’t catch on though, can’t imagine why !  Distortion of the view, I think, was the main argument against, the SE5 “greenhouse” being an obvious example.  If you search for adverts for celluloid, from the period, you will come across the connection with aviation.

Edited August 17, 2020 by HagarTheHorrible

[istari6]

8 hours ago, unreasonable said:

So do I - this is as much an interactive history and engineering lesson as a game.  Possibly sheet mica? You can get extremely thin sheets and therefore very light. I do not know what what actually used, I would guess glass. 

 

Well said!

 

4 hours ago, HagarTheHorrible said:

Yes, Celluloid.  It was even suggested to make a whole aircraft (skin) out of it, to make it invisible, didn’t catch on though, can’t imagine why !  Distortion of the view, I think, was the main argument against, the SE5 “greenhouse” being an obvious example.  If you search for adverts for celluloid, from the period, you will come across the connection with aviation.

 

Huh.  I just read up on celluloid thanks to the comments above.  Had no idea that plastics were available in WWI, but on reflection, it makes sense since they already have the first films in this era.  Just never thought about what was used for filmstock before.    

Edited August 18, 2020 by istari6

[Rail]

http://www.thevintageaviator.co.nz/projects/se-5a-reproduction/flying-se5a

 

[istari6]

One aspect of flying in VR is that you're spending hours in a very real 3D space.  One gets curious about the machine around you.  A few more questions for the group (thanks for the answers so far!):

 

1. Why is there a cutout over the right side of the instrument panel?  Seems like it would create drag for no purpose.  Maybe to let light in to illuminate instruments under high contrast conditions?  E.g. bright day outside, instrument panel in shadow and hard to read otherwise? 

2. What is the electrical device up against the right side of the cockpit side?  It says "Lightning" on the label, is that a mis-spelling of "lighting"?   I didn't think that these early aircraft had cockpit lighting or even batteries, only the magnetos are electrical and run from the engine, right?

3. The tube running up to the Vickers MG is the fluid-based CC interrupter connection, right? 

4. There's a hatch on the right side of the airframe behind the pilot.  On WWII aircraft, this is often where the battery or oxygen tanks are located (see Spitfire).  But I don't think the S.E.5a has a battery and I know it doesn't have O2.  Seems like a strange place to have an access hatch if you're trying to view the cables, since they run lower near the floor of the fuselage.

 

  

Edited August 23, 2020 by istari6

[J2_Trupobaw]

On 8/17/2020 at 11:57 PM, HagarTheHorrible said:

Yes, Celluloid.  It was even suggested to make a whole aircraft (skin) out of it, to make it invisible, didn’t catch on though, can’t imagine why !  Distortion of the view, I think, was the main argument against, the SE5 “greenhouse” being an obvious example.  If you search for adverts for celluloid, from the period, you will come across the connection with aviation.

There was attempt to cover Fokker Eindecker entirely in celluloid. It shone in the sun and was visible at great distances  . And, once the surface started tearing, it would not stop.

[Soilworker]

On 8/17/2020 at 6:52 PM, istari6 said:

Aha.  So it's not just that the fuel is wasted, it's that there's insufficient O2 to get full burn on the baseline amount of fuel that's there (before the excess is counted).  Thus the drop in engine power.  Thanks. 

 

So low mixture = run hot, high mixture = helps cool engine, at cost of some power?

 

(So it's been about 15 years since I learned this and not really used it since, also I've adapted the info to fit aircraft so bear with.)

 

A typical combustion engine needs an stoichiometric ratio of air to fuel to run at peak performance, this is 14.7:1 and is known as lambda. Outside of this ratio performance will suffer relative to how out it is (naturally).

 

So, with the mixture control you're trying to manually achieve this ratio, adjusting for changes in air pressure due to altitude and temperature for when you want the best performance. 

 

Yes, a lean mixture will give better fuel efficiency at the cost of performance and increased engine temperature and a rich mixture can be used to cool an engine at the cost of performance and fuel efficiency. 

 

(Chances are I've screwed up a couple of details but the principle is there.) 

 

Anecdote: A friend of mine who's an ex motorcycle mechanic was telling me about about people failing emissions tests because thier (EFI) motorcycle was too hot and the ECU was trying to cool the engine by enriching the mixture. They would try again later once it had cooled off a bit and pass the test. 

 

Hope this helps with understanding the mixture control. 

[RNAS10_Oliver]

12 hours ago, istari6 said:

1. Why is there a cutout over the right side of the instrument panel?  Seems like it would create drag for no purpose.  Maybe to let light in to illuminate instruments under high contrast conditions?  E.g. bright day outside, instrument panel in shadow and hard to read otherwise?  

 

 

[istari6]

11 hours ago, Soilworker said:

A typical combustion engine needs an stoichiometric ratio of air to fuel to run at peak performance, this is 14.7:1 and is known as lambda. Outside of this ratio performance will suffer relative to how out it is (naturally).

 

So, with the mixture control you're trying to manually achieve this ratio, adjusting for changes in air pressure due to altitude and temperature for when you want the best performance. 

 

Yes, a lean mixture will give better fuel efficiency at the cost of performance and increased engine temperature and a rich mixture can be used to cool an engine at the cost of performance and fuel efficiency. 

 

Great explanation, thank you.  

 

Also- Oliver88, thanks for the confirmation the opening is there for lighting the instrument panel.  

[Soilworker]

10 hours ago, istari6 said:

 

Great explanation, thank you.  

 

 

You're most welcome. ?