SPAD XII-Canon Collector Plane

[Duckman]

On 7/22/2024 at 4:36 PM, Holtzauge said:

 

Absolutely best to go back to original sources and not just trust some quotes or random numbers in a book: This is why I used original French flight test data from STAE like the attached chart when I tuned my SPAD XIII C++ model. However, while the SL speed matches with the numbers you quoted above, STAE (and the performance data in my book) is more optimistic about the top speed at 5 km altitude and the climb time.

 

 

The book looks super interesting. Is there an electronic version available somewhere?

[Holtzauge]

18 hours ago, Duckman said:

 

The book looks super interesting. Is there an electronic version available somewhere?

 

No, only hardback, and I have no plans to do an electronic version myself since I wanted to do a "real" book.

[Duckman]

5 hours ago, Holtzauge said:

 

No, only hardback, and I have no plans to do an electronic version myself since I wanted to do a "real" book.

 

Ok, thanks for the quick reply.

[No.23_Starling]

On 10/21/2024 at 3:20 PM, Duckman said:

 

Ok, thanks for the quick reply.

I can thoroughly recommend it. The best book you’ll find applying modern aerospace science to WW1 aviation

[No.23_Starling]

Hi all, I've found some additional detail on the ammo used in the 37mm weapon. There's a dedicated page to the ammo on Histavia: https://www.histavia21.net/Histoire/munitions_37_Spad-Canon.htm

 

It seems that the rifled barrel and traditional HE type shell was considered unsuitable for air to air engagements, likely due to the accuracy required to hit a solid part of an early aircraft sufficient to trigger the warhead. I've posted photos above of Guynemer posing with the early rounds of this type:

 

 

The French archives show that the rifled barrels were smoothed out and a new type of ammo developed on a grapeshot type principle in early 1918. There are surviving examples of both an early type of this ammo and a more effective later version:

 

 

There is also mention of other types of ammo such as a large incendiary round:

 

 

Records from April 1918 also show that the ammo types were interchangable and all in use, though we can assume a preference for the grapeshot type in air-to-air engagements. We know that the XII-Canon was used to destroy balloons (see quotes above) where an incendiary might have been more effective.

 

 

The last titbit we have is the record of 33 weapons having been delivered by July 1918 which provides a maximum number of types on strength at this point in the war. This does not preclude more airframes and weapons appearing before the end of the war.

 

Giant flying shotguns in 1918. Awesome.

 

 

[ST_Catchov]

MON DIEU! I WANT IT.

[No.23_Starling]

14 hours ago, ST_Catchov said:

MON DIEU! I WANT IT.

There’s a thread on Warthunder’s forum too asking for it to be added now they are moving into WW1

[ST_Catchov]

7 hours ago, US103_Rummell said:

There’s a thread on Warthunder’s forum too asking for it to be added now they are moving into WW1

 

WW1 you say. It's about time they got real. 👍

[No.23_Starling]

All, another photo find below. This time it’s from Nanterre university in Paris. It’s a close up shot of a XII’s cockpit with a curious caption regarding incendiary rockets. There’s lots of photos of VIIs and XIIIs fitted with rockets but none of XIIs, plus the XII had its own 37mm special incendiary round.

 

The photo looks like an early XII Canon, likely spring 1918 and possibly one of Fonck’s. Clearly visible is the Vickers gun ejection chute on the left and the fuel cap between the port cabane struts. It also looks like the RPM gauge has been removed near the MG butt in the cockpit. Open butterfly clips on the engine cowling suggests maintenance. Of interest is also the SPAD XIII windscreen and ring and bead sight. It seems the XII was modified with a variety of windscreens.

 

 

[No.23_Starling]

On 9/2/2022 at 11:52 AM, Holtzauge said:

 

For sure: They had different engine designations which of course is only logical since one could house an engine cannon and the other didn’t. But I think the most important thing here is the power: Even if one had a different gearing than the other, this would only result in a different rpm and torque combination, the power would still be the same. In my simulations I assume that whatever power is produced, is matched with a proper propeller and then it does not matter what gearing is used as long as the propeller matches the torque and rpm. So if the SPAD 12 and 13 had different gearing should not affect the results by much, provided both had a matching propeller mounted.

 

However, the distinction if it was a 200 or 220 hp engine is of course important but those numbers are given in the conditions as far as I can tell. In addition, as far as I know the higher CR Hispanos did not have a knock limitation at low level like some of their German engines, meaning that the 200 or 220 hp was available a SL and was then reduced in proportion to the lowered air density as the altitude went up. At least that is what I have been assuming for the 200-220 hp Hispano so far.

 

Hey @Holtzauge, further digging into the French archives I've come across an STAe bulletin from April 1918 which covers a number of SPAD tests including on the XIII with rounded and squared wings. There's inclusion of climbing tests for SPAD Canon XII, airframe S.440 - the testplane attached to STAe. You'll notice considerably improved climb performance from the other - likely 1917 - test I shared in this thread. The other test data I shared has the additional loaded weight as 290kg; here it is given as 260kg. According to Yavor over on the Aerodrome forum the fuel load was reduced so the total weight matched the loaded SPAD XIII (98kg fuel reduced to 63kg).

 

Even with this 35kg reduction the climbn speed improvement over the 1917 tests are substantial. Any idea what's going on here? The other test has the ground level HP output as 240hp so it seems both engines used the higher compression. 

 

 

 

[LukeFF]

[No.23_Starling]

On 6/30/2025 at 5:34 AM, LukeFF said:

Brilliant! I’ve not seen that before! Thanks!

[Avimimus]

Interesting! So, the S.XII was still in service in 1918 and used some of the new rounds? I'd always assumed that only the S.XIV received those - but it was just an assumption on my part.

[No.23_Starling]

On 8/5/2025 at 3:16 AM, Avimimus said:

Interesting! So, the S.XII was still in service in 1918 and used some of the new rounds? I'd always assumed that only the S.XIV received those - but it was just an assumption on my part.

I’ve only found evidence of the XII using either canister shot rounds or high explosive. HQ ordered all canon to get smooth bore modifications in the summer of 1918 to help the canister round accuracy, but the old rifled barrel

was still interchangeable.

 

The XIV probably didn’t see combat given how few were on station in Nov 1918.