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Data Showing Incorrect Engine Used In The SPAD XIII, Its Impact On Performance & Proposed Corrections

US103_Baer

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US103_Baer

US103_Baer

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Data Showing Incorrect Engine Used In The SPAD XIII For Flying Circus

& Proposed Engine Variants

 

 

Brief description: The SPAD XIII in FC uses a 200hp engine, not 220hp. This is provable through both Hispano-Suiza engine model documention, and historic flight test performance.
 


Detailed description, conditions:

 

- Section 1: Overview -

 

  • The Spad XIII in Flying Circus is specified as a 220hp model using the Hispano-Suiza HS 8Ba.

 

  • Using a variety of data sources collected from extant engines and published in peer-reviewed and widely well-regarded publications, we can show that the FC Spad XIII in fact uses a 200hp engine model and that its performance is in-line with that of a 200hp Spad XIII. (See section 2 and 3)

 

  • This being the case, two recommendations are made to improve the Flying Circus simulator.
  1. Leave the existing Spad in place and redesignate it as a 200hp HS8Ba powered SPAD XIII
  2. To re-model a 220hp SPAD XIII with the HS 8BEc using the Ratmanoff 6727 propeller. This engine/airframe combination has excellent published data to support max hp, rpm and flight-tested speed and climb performance.

 

  • Both these models should then align with published model numbers, specifications and performance data for both the aircraft and engine.

 

 

- Section 2: Engine Model -

 

  • The HS 8Ba was a standard compression 200hp engine, not 220hp. See table 2 below. (Hispano-Suiza in Aeronautics: - Appendix II p481)

 

  • The 200hp (4.7:1 compression) engines were known as Type 35. The 220hp engines were higher compression (5.3:1) Type 35Bis or 35S

 

  • Table 2 (HS&A p481) below clearly lays out the Type 35 (Bis/S) engine development and power. The first of these 220hp engines is the HS 8Bc.

 

Table 2  (Screenshot of Appendix II - Hispano-Suiza in Aeronautics:Men, Companies, Engines and Aircraft, Lage, 2003, p481)

image.thumb.png.8ea4e0a18c4affb010f506031f3be894.png

 

KEY POINTS

 

  • Power naming designations like 200hp or 220hp SPAD are based on Nominal HP. It can be seen in Table 2 that the ‘200hp’ Type 35 engines actually produced a max 210-219hp at 2000 - 2240rpm. Likewise the 220hp engine would produce up to 238hp at 2240rpm.

 

  • Table 2 does not give a max power/rpm for the initial model of Type 35Bis (220hp) engines (HS 8Bc), stating simply its nominal output of 223hp/2000rpm. Using the conservative 5% scaling achieved by the 200hp engines, that translates to an expected max of 234hp/2240rpm

 

  • Note: Gearing 2000/1500 for fighters and 2000/1333 for twin-engined aircraft (HS&A p42)

 

220hp ENGINE OPTIONS

       The 220hp engine options for Flying Circus are therefore:

  1. HS 8Bc achieving 234hp at 2240rpm (extrapolated performance from nominal hp - max hp scaling of earlier models)
  2. HS 8BEc 238hp at 2240rpm
  3. HS 8BEe at 238hp at 2240rpm.

 


- Section 3: SPAD XIII Speed/Climb Performance -

 

The table below collates and compares performance data from the published references listed, Flying Circus SPAD XIII Specifications and In-game testing. For easier comparison IAS speeds were converted to TAS using this well-regarded Aviation Calculator

 

image.thumb.png.ea991406580303871042612b51fb5feb.png

 

 

KEY POINTS

  • 218kph is the most commonly quoted top speed at 2000m. This aligns exactly with the September 1917 tests using the Ratmanoff 6727 prop and HS 8BEc engine.

 

  • Max speed attained with Flying Circus in-game at 2000m is 208kph TAS (189kph IAS), Thus not reaching its spec speed which is itself lower than the published data provided. In-game tests were replicated with multiple pilots using Kuban autumn, clear weather.

 

  • Flying Circus in-game speeds are extremely close to the 200hp data from Soltan & Davilla, demonstrating that FC does not simply suffer from a typo regarding engine model.

 

Key Performance comparisons:  200hp performance, Actual In-game performance & common 220hp Spad performance.

JTdZYkRGapX5A67JRovhyQn7Ju3OH-1vLtpoMbwI5OtFm7ymrznimPd9SCVwfuORvRXRZPx1CXSheCP35zP7C6J-TWPSG83PeZNRnHp_uG-8xVjlw8na4jWdyIvxALYHSCp28e3r

 

 

- Section 4: Recommendation -

  • The recommendation is therefore to modify the 220hp Spad XIII in FC to use the Hispano-Suiza HS 8BEc (238hp/2240rpm) with Ratmanoff 6727 propeller (Prop data provided below).

 

  • Leave the existing Spad in place and redesignate it as a 200hp SPAD XIII

 

  • Both these models should then align with published model numbers, specifications and performance data for both the aircraft and engine.

 

 

- Appendix: In Flight Test Captures-

 

Max speed 215kph IAS at 25m. Kuban, autumn, morning

image.thumb.jpeg.a76fc3bc035af98a4ff25855ee241128.jpeg

 

 

 

Max speed 189kph IAS at 2000m (208.3kph TAS)  Kuban autumn morning

image.thumb.jpeg.99d4d9af0535b08e79ff9c6931bcf3ff.jpeg

 

 

Spad Propeller Data - Screenshot from ‘AEF Catalogue’

image.jpeg.2236be4c3df4062a903d8c9180e0f3d9.jpeg

 

 

 

- Acknowledgements-
The data presented is a result of efforts from a number of community members. Many thanks to @Garven / @94th_Vernon @US213_Talbot @US93_Larner @US213_Doolittle and @US28_Baer

Edited by US28_Baer
  • Thanks 4
  • Upvote 10
  • US103_Baer changed the title to Data Showing Incorrect Engine Used In The SPAD XIII, Its Impact On Performance & Proposed Corrections
jeanba

jeanba

Posted
Posted (edited)

will update with further documentation

Edited by jeanba
US103_Baer

US103_Baer

Posted
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Posted (edited)
18 hours ago, jeanba said:

I globally agree with your figures

Anyway, there should be 3 versions of the Spad 13:

200 hp

220 hp

235 hp

Thanks.  Is what we thought for ages too, and it's caused a lot of confusion over the years.

However you can see that, according to factory info above, a 220hp WAS capable of 238hp. The difference being between nominal hp and max hp. 

ALL the '220hp' engines were capable of 234+ hp at max output. There are no nominal 235hp engines listed.  

Naming uses the nominal hp rating.

 

Edited by US28_Baer
unreasonable

unreasonable

Posted
Posted

Great post - perfect example of how an FM/DM issue should be presented, although I know that such good documentation is not always available.

 

Let us hope that at least this will go into someone's in tray for a developer response. 

  • Thanks 1
  • Upvote 1
jeanba

jeanba

Posted
Posted (edited)

will update with furthdocumentation

Edited by jeanba
J99_Sizzlorr

J99_Sizzlorr

Posted
Posted

Was the 220 hp engine able to give out 235hp constantly or would the engine seize if you flew full throttle all the time?

ZachariasX

ZachariasX

Posted
Posted
4 minutes ago, J99_Sizzlorr said:

Was the 220 hp engine able to give out 235hp constantly or would the engine seize if you flew full throttle all the time?

You can only have that at sea level. The catch is here that you have the same fraction of power from 200 hp than from 235 hp at 3000 m, where the actual output is considerably lower than 235 hp and you can have open throttle all day long. Hence, unless you have a boat with that engine, it will be around 220 hp max output anyway and you are safe.

  • Thanks 1
jeanba

jeanba

Posted
Posted (edited)

will update with further documentation

 

Edited by jeanba
  • Thanks 1
No.23_Triggers

No.23_Triggers

Posted
Posted

Should this topic maybe be moved to "Historical Data"? 

 

  • Upvote 1
ZachariasX

ZachariasX

Posted
Posted (edited)
26 minutes ago, US93_Larner said:

Should this topic maybe be moved to "Historical Data"? 

That‘s probably a good idea given the quality of the OP.

 

But it would be nice if we kept the section such that the discussion of an individual technical posting is discussed in a sepatate thread to keep it clean like the dev diaries.

 

Currently, I am working on a documentatation of the function of the Höhengas on the so called „overcompressed“ engines. I still need some input from other knowledgeable folks, but I plan on publishing it in that section. Suffice to say that Höhengas has nothing to do with what we have it in FC (and RoF for that matter), neither in purpose, nor in function.

Edited by ZachariasX
  • Upvote 1
jeanba

jeanba

Posted
Posted

I deleted my posts, I will update them with documentation, this way, the topic will be clearer

US103_Baer

US103_Baer

Posted
  • Author
Posted
On 10/16/2021 at 4:24 PM, jeanba said:

I deleted my posts, I will update them with documentation, this way, the topic will be clearer

Thanks.  Interested to see how the French categorised them.

Post in a separate discussion or historical data thread if can.

 

I wanted this to be a bug report supported by data. Unfortunately they haven't really given us such a forum section, so it's here.  Will add into Historical Data section as well as there is some hard to find data here. 

  • Like 3
No.23_Triggers

No.23_Triggers

Posted
Posted

@SYN_Haashashin or some other mod, any chance this could be moved into the FC Historical Data subforum? I think given the quality of OP it's better suited to being in there. 

 

  • 1 month later...
volatile_void

volatile_void

Posted
Posted (edited)

@US28_Baer Some time ago I discovered that the Safran Group (successor of Snecma) has some WW1-era aircraft engine manuals on their archive site.
The archive also contains an engine manual for Fives-Lille built Hispano-Suiza engines, which shows power/rpm curves for the 8Aa, 8Ab, 8Bb and 8Bc engines on plate VII.

 

Hispano-Suiza engine manual (Compagnie de Fives-Lille): https://heritage.medialibrary.safran-group.com/Heritage/media/63517

 

The curves agree with the numbers given in Table 2 in the original post (although no altitude data given as far as I could see).
I thought I just add this here as additional reference.
 

For those interested also in other french WW1-era engines there are some more links into their archive:

Spoiler

Renault 80 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/50374051
https://heritage.medialibrary.safran-group.com/Heritage/media/50374047

 

Renault 130 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/50374536

https://heritage.medialibrary.safran-group.com/Heritage/media/50374046

https://heritage.medialibrary.safran-group.com/Heritage/media/50374541

 

Renault 170 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/15374

 

Renault 190 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/50374050

https://heritage.medialibrary.safran-group.com/Heritage/media/50374539

 

Renault 220 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/50374053

https://heritage.medialibrary.safran-group.com/Heritage/media/50374535

https://heritage.medialibrary.safran-group.com/Heritage/media/50374540

 

Renault 300 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/15099

https://heritage.medialibrary.safran-group.com/Heritage/media/15375

https://heritage.medialibrary.safran-group.com/Heritage/media/50374049

https://heritage.medialibrary.safran-group.com/Heritage/media/151259

 

Lorraine 160 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/179161
https://heritage.medialibrary.safran-group.com/Heritage/media/50374369

 

Lorraine 220 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/50374549

 

Salmson M (M7 & M9):
https://heritage.medialibrary.safran-group.com/Heritage/media/50374055

 

Salmson A9 & R9:
https://heritage.medialibrary.safran-group.com/Heritage/media/50374057

 

Salmson 9Zm:
https://heritage.medialibrary.safran-group.com/Heritage/media/50374058

 

 

Edited by volatile_void
  • Thanks 2
US103_Baer

US103_Baer

Posted
  • Author
Posted
3 hours ago, volatile_void said:

@US28_Baer Some time ago I discovered that the Safran Group (successor of Snecma) has some WW1-era aircraft engine manuals on their archive site.
The archive also contains an engine manual for Fives-Lille built Hispano-Suiza engines, which shows power/rpm curves for the 8Aa, 8Ab, 8Bb and 8Bc engines on plate VII.

 

Hispano-Suiza engine manual (Compagnie de Fives-Lille): https://heritage.medialibrary.safran-group.com/Heritage/media/63517

 

The curves agree with the numbers given in Table 2 in the original post (although no altitude data given as far as I could see).
I thought I just add this here as additional reference.
 

For those interested also in other french WW1-era engines there are some more links into their archive:

  Reveal hidden contents

Renault 80 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/50374051
https://heritage.medialibrary.safran-group.com/Heritage/media/50374047

 

Renault 130 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/50374536

https://heritage.medialibrary.safran-group.com/Heritage/media/50374046

https://heritage.medialibrary.safran-group.com/Heritage/media/50374541

 

Renault 170 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/15374

 

Renault 190 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/50374050

https://heritage.medialibrary.safran-group.com/Heritage/media/50374539

 

Renault 220 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/50374053

https://heritage.medialibrary.safran-group.com/Heritage/media/50374535

https://heritage.medialibrary.safran-group.com/Heritage/media/50374540

 

Renault 300 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/15099

https://heritage.medialibrary.safran-group.com/Heritage/media/15375

https://heritage.medialibrary.safran-group.com/Heritage/media/50374049

https://heritage.medialibrary.safran-group.com/Heritage/media/151259

 

Lorraine 160 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/179161
https://heritage.medialibrary.safran-group.com/Heritage/media/50374369

 

Lorraine 220 hp:
https://heritage.medialibrary.safran-group.com/Heritage/media/50374549

 

Salmson M (M7 & M9):
https://heritage.medialibrary.safran-group.com/Heritage/media/50374055

 

Salmson A9 & R9:
https://heritage.medialibrary.safran-group.com/Heritage/media/50374057

 

Salmson 9Zm:
https://heritage.medialibrary.safran-group.com/Heritage/media/50374058

 

 

This is awesome.  Thanks so much.  Great data is out there, the trick is finding it. Really appreciate the share.

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