Does Vx IAS increase with altitude or not?!
Thread Starter
Joined: Dec 2013
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From: Baleares
Thanks for all the help bu I am officially confused (again).
This is the second major discrepancy between my OAA principles of flight textbook.
1. OAA repeatedly say that for a reciprocating, normally aspirated prop aircraft, Vy is the same TAS as Vmd whereas my instructor tells me that EASA expect Vmp.[ I think it is neither and merely the speed of max. excess power.]
2. That Vx IAS increases with Density Altitude.
very frustrating, who to trust?!
This is the second major discrepancy between my OAA principles of flight textbook.
1. OAA repeatedly say that for a reciprocating, normally aspirated prop aircraft, Vy is the same TAS as Vmd whereas my instructor tells me that EASA expect Vmp.[ I think it is neither and merely the speed of max. excess power.]
2. That Vx IAS increases with Density Altitude.
very frustrating, who to trust?!
Joined: May 2005
Posts: 1,115
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From: Yorkshire
I think it is neither and merely the speed of max. excess power.
Vy should only be the same as either Vmp, or Vmd when both Vmp and Vmd are the same.
Oxford really need to get these things straightened out with their students!
MJ
Joined: Mar 2013
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From: EU
1. OAA repeatedly say that for a reciprocating, normally aspirated prop aircraft, Vy is the same TAS as Vmd whereas my instructor tells me that EASA expect Vmp.[ I think it is neither and merely the speed of max. excess power.]
Joined: May 2001
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I suspect both will be right but for different reasons.
1. Oxford will know that there is a question where the answer is what they have told you.
2. The other instructor is right because that's the way it actually works in real life.
from memory from quite a few years ago now there were several topics which they were looking for an answer which if you had an engineering degree where a load of rubbish.
In fact when doing the brush up course there was a couple of us who would start to ask a question and just get told "the world according to JAR" and that was the only answer we needed.
1. Oxford will know that there is a question where the answer is what they have told you.
2. The other instructor is right because that's the way it actually works in real life.
from memory from quite a few years ago now there were several topics which they were looking for an answer which if you had an engineering degree where a load of rubbish.
In fact when doing the brush up course there was a couple of us who would start to ask a question and just get told "the world according to JAR" and that was the only answer we needed.
Thread Starter
Joined: Dec 2013
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From: Baleares
In fact when doing the brush up course there was a couple of us who would start to ask a question and just get told "the world according to JAR" and that was the only answer we needed.
Originally Posted by OhNoCB
It is generally accepted for exam level that for piston aircraft, Vy is roughly equal to Vmd. It is also generally accepted that Vx is roughly 1.1Vs but the exams assume it to be Vmp. Your statement above suggests that either you're instructor or your quote has slightly mixed the two speeds up in that case.
Perhaps it is a Spanish thing! I am in Mallorca taking the AESA PPL(A)
