Groundspeed
Pompey till I die
Joined: Nov 2006
Posts: 779
Likes: 0
From: Guildford
205kts in my 172 a few weeks ago coming back from Guernsey and 280kts a couple of years ago in the baron. Slowest was the same Cessna flight out to Guernsey when I had a 46kt ground speed at one point!
Joined: Sep 2003
Posts: 0
Likes: 0
From: UK,Twighlight Zone
A 172 XP at a cruise is closer to 130kts actually so wind was closer to 80kyts. 200ish HP, wobbly prop. 17,000ft close on 150kt TAS. I think you are confusing air speed and ground speed.
If you fly at 100kts indicated airspeed at 2000ft and the wind is 50kts up the tail, you are still only doing 100kts through the air but are doing 150kts over the ground. Go to 10,000ft and your indicated airspeed is still 100kts, your TAS is about 110kts. The wind at 10,000ft is now more in the region of 80kts (allthough often the wind aloft can be virtually nothing and it is blowing a gale on the ground) so add the 80kts to your 100+10kts and you have a GS of 190kts but your are still only indicating 100kts. VA is based on indicated airspeed so VA in my Cessna is approx 130kts so I still have a 30kt margin.
Gusty conditions and flying beyond VA are a problem, a constant strong flow is not. When flying in the airways 1000ft can make a difference of 30kts and some times 90d direction, so we choose our cruise based on the most favourable winds. If I get an 80kt tailwind at 14,000ft or only 30 at 8,000ft I am going to get the O2 kit out and climb. I have seen some very strong winds at altitude and try to use them to my favour. The jetstream can get into the 100s of kts range and airliners try to use this to there advantage in fuel and time savings.
If you fly at 100kts indicated airspeed at 2000ft and the wind is 50kts up the tail, you are still only doing 100kts through the air but are doing 150kts over the ground. Go to 10,000ft and your indicated airspeed is still 100kts, your TAS is about 110kts. The wind at 10,000ft is now more in the region of 80kts (allthough often the wind aloft can be virtually nothing and it is blowing a gale on the ground) so add the 80kts to your 100+10kts and you have a GS of 190kts but your are still only indicating 100kts. VA is based on indicated airspeed so VA in my Cessna is approx 130kts so I still have a 30kt margin.
Gusty conditions and flying beyond VA are a problem, a constant strong flow is not. When flying in the airways 1000ft can make a difference of 30kts and some times 90d direction, so we choose our cruise based on the most favourable winds. If I get an 80kt tailwind at 14,000ft or only 30 at 8,000ft I am going to get the O2 kit out and climb. I have seen some very strong winds at altitude and try to use them to my favour. The jetstream can get into the 100s of kts range and airliners try to use this to there advantage in fuel and time savings.
Joined: Dec 1999
Posts: 3,077
Likes: 1
From: Oop North, UK
Surely the C172 would break apart easily ?
