New structural G-limit feature

[Bellator]

Well if they use the real life limit load factors then it would be pretty bad for Spitfire pilots as the limit load factor for the Spitfire was some 5.33 G's compared to the std. German 8 G's and US 7.33 G's.

But then again, most pilots back then blacked out at around 4 G, so anything above 5 G is gonna entail flying in the blind anyway

[Tempest123]

Originally Posted by Bellator

Well if they use the real life limit load factors then it would be pretty bad for Spitfire pilots as the limit load factor for the Spitfire was some 5.33 G's compared to the std. German 8 G's and US 7.33 G's.

But then again, most pilots back then blacked out at around 4 G, so anything above 5 G is gonna entail flying in the blind anyway

5.33 g's for a spitfire max g-limit? Where does this information come from? For example the F8F Bearcat was restricted to 7.5 g's after failures of its wingtip ejection system, I highly doubt that a lighter and smaller fighter which saw exponentially more combat than the Bearcat, and with no history of chronic failures would have a limit of 5.33 g's. The g-limit would vary between aircraft, not between countries.

[AndyJWest]

I'd be wary of comparing G-limits between aircraft without being sure that they were actually measured the same way. An operational G limit would presumably be based on the expected failure point, minus a safety factor. But would all safety factors be the same? Unless you know this, you can't make comparisons.

[Bellator]

Originally Posted by Tempest123

5.33 g's for a spitfire max g-limit? Where does this information come from? For example the F8F Bearcat was restricted to 7.5 g's after failures of its wingtip ejection system, I highly doubt that a lighter and smaller fighter which saw exponentially more combat than the Bearcat, and with no history of chronic failures would have a limit of 5.33 g's. The g-limit would vary between aircraft, not between countries.

Now according to what I've read British aerospace std. requirement was a limit load factor of 5.33 G for their fighter aircraft, and the Spitfire was designed & built according to this. The German aerospace std. limit load factor was by comparison 8 G's and the US std. was 7.33 G's

The advantage of the lower British std. was the ability to build their aircraft somewhat lighter.

The ultimate design load factor is usually found by multiplying the design limit load factor by 1.5, at which point you arrive at the designs breaking point. So the Spitfire should be able to take 7.99 G's before breaking up, whilst aircraft such as the Bf-109, P-51 & Fw190 could take between 11 to 12 G's before breaking up.

[AndyJWest]

'British aerospace'? Anachronistic to say the least in relation to WW 2 aircraft.

Can you provide references, Bellator? Including the safety factors that otherwise make such figures of little significance. As I've already said, you have to compare like with like.

EDIT
I've found a recent thread on the Ubi forum that refers to this - it appears that British, US, and German standards were different: http://forums.ubi.com/eve/forums/a/t...8531075258/p/3

[Bellator]

Hi Andy,

Like I said it's only what I've read, but it seems to be true enough.

Kettenhunde at the Ubi forum knows it better than me it seems though:

That margin for damage to the airframe is "1" for US, British, and French aircraft, Bill. In technical terms, that means there is no margin.

That means if it says 6G, then the aircraft will be damaged if you exceed that limit. There is no buffer from the published limits.

The Germans had a 1.35 margin of safety for damage limits. That means there is a buffer from the published limits if you make a comparison to United States, Britain, and French standards. In other words, for the same airframe strength, the Germans will publish lower limits. If the published limits are the same, the German aircraft is stronger.

The United States, Britain, and France had a 1.5 margin of safety limit for airframe failure. The Germans had a 1.8 margin of safety limit for failure.

[AndyJWest]

Bellator, I understand what you are saying, but I'd be a bit wary of taking such figures too literally - they seem to imply (a) that there is a fixed ratio between G force necessary to cause airframe damage and that needed to cause failure, and (b) this ratio differed between Allied and Luftwaffe aircraft.

It's worth noting, at least in passing, that there are suggestions in the thread that early Spitfires were designed for 10 G loads, and actual tests on wings exceeded this.

[JtD]

Spitfires failed past 12g's. Tested.
The handbook says 10g starts to be unsafe (Spit II).

Bottom line: 5.33g might have been a minimum requirement for British fighter aircraft of the day, but the Spitfire could take far more. It's pretty much the same a Fw could take.