China's transport, tanker & heavy lift aircraft
- Thread starter Totoro
- Start date
Is 111% good enough ? was expecting Y-20 to at least reach 140/150% (being a military aircraft)
For 777 it was 154%
Making a wing have higher strength resistance typically requires having more weight to strengthen it. So having a really high resistance in the design isn't necessarily a good thing. It might mean you overdid things and ended up with a heavier aircraft than you needed to. IIRC 20% safety margin in a wing design is typically considered perfectly normal. So yes 11% margin, without extra information, seems kind of low. But you would have to know more with regards to the original test requirements to really judge it.
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Here is the answer, explained at about 8:30
111% is delibrately set. Too high is a failure of overengineering and overweight. The design objective was no more than 120%. I was surprised at first just like you untill after watching three times and listened to the explainations.
To the contrary, higher limit is the requirement of civilian airliners, C-919 maintained 3 seconds at 150% which is stated in the same video above at 7:16. It also means that the breaking load could still be a little higher.
[addition]
C-919 and Boeing 777 are both twin engines, when one of their engines fails, they will try to restart by diving. This will create high load to the wings. A four engine aircraft has much less chance of needing to do it, therefor lower requirement even for a civilian aircraft. This explains why civilian goes to twin engine to save fuel cost, but also increase load requirement. It is a balance taken for maximising profit. Military aircraft is less sensitive to economy, but want robustness therefor 4 engines.
I think there is a common misconception that everything military must have higher figures than civilian, another example is CPU clock speed. In reality, military has its own application environment with different sets of disirables.
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Could you explain a bit more what you mean by “deliberately set”? 111% seems a bit too even even for four engine military aircrafts. What if the Y-20 had to do extreme maneuvers ( like the C17 did through valleys and downtown Sidney). Can it still do that or fly through hurricanes with 111% though? Sorry i am terrible in details of aviation physics lol. I’m political science major lol
made some good points. please explain.
C17 or A400M, they both have a 150% limit target.
That’s my question here, too. Why lowering the standard to 111%, or was it because that was AVIC optimum capacity back in 2012? Alway does anyone have the same information on Il-76? It is possible that the stands could be based on Soviet ones because they were the only ones China had detailed access to.
its actually 120% as per the video.. still low considering other Military airlifter.
C919 achieved 150% back in 2018. so i doubt there was a bottleneck or some material limit of AVIC from 2015 onward.
this 'destructive test footage' is from early variant of Y-20.
i believe Y-20B is a lot different aircraft as compared to early variants.
waiting for @taxiya answer..
Well we don’t know if Y-20B has been improved to withstand 150%. The issue is now the PLAAF already has hundreds of 110-120% only Y-20A in service. I wonder if these Y-20As could operate in extreme weathers. The most challenging operations that the Y-20 had accomplish so far were the deliveries of HQ-22 to Serbia and COVID aids to pacific island nations. But based on publicly available images, those operations had been accomplished in mild weather conditions with clear skies. And of course, Y-20A is capable of landing and taking off from the Tibetan plateau with reduced loads.