- Dec 27, 2005
- Reaction score
удельный вес means specific weight, the machine translation used the word gravity instead of weight, and the article provided the explanation about what they are referring too, even if you don't want to check the translation for accuracy. You are also ignoring the rest of the evidence I provided. The density of an engine is not a meaningful parameter and cannot be 0.1, unless you are willing to accept it weights 180 kg by your proposed definition...@LMFS Specific gravity can't be "defined in the article" it is a standard engineering parameter. You can't just redefine it to mean something different, and the explanation of specific gravity in the article is presumably by the journalist. Either the wrong word was used or the meaning ascribed by the journalist was incorrect.
Russian wikipedia says otherwise:
Specific gravity is a physical quantity, which is defined as the ratio of the weight of a substance P to the volume V occupied by it.
Weight per volume being decreased could correlate to higher thrust to weight but not directly.
I am not being obtuse, believe me. To get an increase in thrust both mass flow and specific thrust can and are normally increased, check for instance the different versions of the AL-31F in this regard. Say the thrust increase is 20% (to have rounder numbers), a 15% can come from specific thrust and a 5% from mass flow, for instance, or viceversa The increase of mass flow does not mean a reduction specific thrust, since it does not imply a higher or lower BPR.Also you seem to being deliberately obtuse in regard to your mass flow argument. The article specifically says specific thrust is increased. This means more thrust per unit of mass flow. If thrust of Izdeliye 30 is say 17500kg compared to 15000kg for Ideliye 117, thats 16.67 % increase in thrust. By the terms of this article, if the mass flow if Izeliyie 30 is higher, then that reduces the increase in specific thrust. Its possible that mass flow is slightly higher (say, 5%), but if mass flow of Izdeliyie was 20% higher, for 17% more thrust, then specific thrust would be LOWER than Izd. 117. This is basic maths not advanced engineering.
As to the corresponding thread, yes please move the posts where you see them fit.
You have been arguing that Izdeliye 30 has a significantly higher mass flow rate and advanced opinions on the intakes being greatly oversized etc for supercruise optimisation for several pages.
When confronted by the engine designer saying that supercruise optimization depends on higher specific thrust not increased mass flow, doesn't that theory go out the window?
SFC being the same could mean a lower bypass ratio (for higher speciic thrust) combined with higher efficiency due to TET increase cancels each other out rather than being a hidden clue to VCE.