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Help and Support Forums => Technical Support => Topic started by: lunatic1 on December 27, 2016, 05:59:59 PM

Title: KI-84 470mph IAS
Post by: lunatic1 on December 27, 2016, 05:59:59 PM
I was in a yak-3 in a dive 470mph IAS- and ki-84 was 800 behind me- and then I leveled off ki-84 was then 600 behind me. others say a ki-84 can't do 470 without compressing or breaking something. but this one did..don't know if this right place to post this..but according to speed chart 350 or 375mph is max. can you all check on this and correct it if it is wrong..thank you
Title: Re: KI-84 470mph IAS
Post by: Ack-Ack on December 27, 2016, 06:38:06 PM
film?  The film would show the speed or a screenshot with the alt/speed indicator in the upper corner would work as well.
Title: Re: KI-84 470mph IAS
Post by: Chalenge on December 27, 2016, 06:38:34 PM
The never exceed speed for the Ki-84 is nearly 500mph. Every airplane can exceed its maximum speed, which I believe is measured as the speed an airplane may attain under its own power in level flight. Diving will always be faster.
Title: Re: KI-84 470mph IAS
Post by: Zimme83 on December 28, 2016, 06:25:45 AM
And if u, like for ex me, have elevator trim mapped on the joystick you can use it to pull up even if you are compressing..

But without a video its a pointless debate, a guy whined about "a Brewster going 500 mph" and when i looked at the video the dive speed of the Brewster was 325 mph...
Title: Re: KI-84 470mph IAS
Post by: Skuzzy on December 28, 2016, 10:06:37 AM
I moved this to the Tech Support forum.  Without a film, we have no way of answering the question.  As to whether it is a bug, or not, we have no way of knowing without a film.
Title: Re: KI-84 470mph IAS
Post by: morfiend on December 28, 2016, 05:49:26 PM
There are several reasons this could happen! The Ki84 doesnt compress until above 500 mph,it can shed parts at much lower speeds but as was already said the use of trim can allow the pilot to pull out without breaking the plane!

  Then there's angle of attack or pursuit, the 84 could have used a slight lead pursuit and gained on you in the pull out!

 All of this is just speculation,without film we will never know the real answer.

 YMMV.


    :salute


Title: Re: KI-84 470mph IAS
Post by: Dobs on December 29, 2016, 09:49:45 AM
What is missing in the FMs (and in everygame I've played as well) is critical mach number  and subsequent mach induced drag.

A brief, yet decent discussion is here :https://en.wikipedia.org/wiki/Critical_Mach_number (https://en.wikipedia.org/wiki/Critical_Mach_number)

Hand in hand is the resulting Drag divergence https://en.wikipedia.org/wiki/Drag_divergence_Mach_number (https://en.wikipedia.org/wiki/Drag_divergence_Mach_number) "where drag can increase up to 10 times its normal value".

So essentially all planes dive "better "Than they should" and this, IMO, is why we have the might brewster diving with the known high speed capable aircraft...the associated drag build up is not present.

You can find much more in depth sources for this if you look for it, but it bores the tears out of most. 

Essentially the fatter the wing, the lower its mach capability and the higher the mach induced drag penalty.   America's  Hundred Thousand states the F4F had a TERMINAL dive velocity of 410IAS (483 TAS) @10,000', and goes on to say the aircraft "hardly had to worry about compressability effects since terminal velocity at 10000 feet represented Mach .66."  Which pretty much sums up fat wing>mach drag increase at speed...