I used to fly to a 2000' grass strip[Embrun, On] in a 172 P model [ 30 degree flaps]
With half tanks and just me the landing ground roll was very close to 500'
POH/AFM Book Values Are Full Of Shit
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John Swallow
- Posts: 319
- Joined: Fri Jun 03, 2016 1:58 pm
The manual for a ’78 Skyhawk (N series) indicates a stall between 36 knots and 41 knots, C of G dependant. So, assume a forward C of G and a stall of 40 knots, one should be able to bleed from the approach speed of 70 knots to cross the button at no more than 45 - 50 knots. A touch down shortly after should result in a ground roll that meets the book figure, wouldn’t you say? My N manual only lists landing distances for the short field technique and that is listed as 495 feet at sea level. I think a current, competent pilot could achieve that – or damn close!
BTW, the “Approach speed†on the example described IS listed as 70 knots, but who the hell crosses the button at the approach speed? The technique indicated for the “N†model says 60 knots at 50 feet. 55 knots across the button should be a dawdle for anybody half-way competent and 50 knots or less with practice.
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Slick Goodlin
- Posts: 721
- Joined: Thu Jun 11, 2015 6:46 pm
[quote author=John Swallow link=topic=9515.msg27011#msg27011 date=1551762195]
BTW, the “Approach speed†on the example described IS listed as 70 knots, but who the hell crosses the button at the approach speed? The technique indicated for the “N†model says 60 knots at 50 feet. 55 knots across the button should be a dawdle for anybody half-way competent and 50 knots or less with practice.
[/quote]
That's the way I read it too. It would be interesting to try and force it on doing 70, I imagine it would look like this:
[img]https://i.gifer.com/D2VF.gif[/img]
BTW, the “Approach speed†on the example described IS listed as 70 knots, but who the hell crosses the button at the approach speed? The technique indicated for the “N†model says 60 knots at 50 feet. 55 knots across the button should be a dawdle for anybody half-way competent and 50 knots or less with practice.
[/quote]
That's the way I read it too. It would be interesting to try and force it on doing 70, I imagine it would look like this:
[img]https://i.gifer.com/D2VF.gif[/img]
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Colonel
- Posts: 3450
- Joined: Wed Apr 29, 2015 10:31 am
[quote]anybody half-way competent[/quote]
Back in the real world, the most marginal candidate I ever signed off
for an L39 type rating was a retired Air Canada pilot. He had all the
hours. His ATP had all the types from flying up north - he had his ticket
punched. I figured he must know what he was doing, right?
But, he liked to come in fast, and land the L39 half-way down the 4,000
foot runway and lock up the brakes. This is a common error I see with
pilots these days - they approach much too fast, "for safety". Sigh.
Ok, but that means that they will never be able to obtain the hopelessly
optimistic book numbers. So, I suggest adding a correction factor of x2.
At my current home airport, there is a very long runway (to me - 5,200 feet)
and a "short runway" (2700 feet). Every time I am there flying the Pitts solo,
the Cessna and Piper pilots insist on using the 5200 foot runway and I am
using (solo) the short runway in the S-2B. It's fucking hilarious.
I routinely make the half-way turnoff after landing on the "short" runway for
taxiway Q which is 1300 feet, and I approach long final at 180 mph, then
160 mph, then 140 mph, then 120 mph short final, then touchdown at 100 mph.
Needless to say, the Cessna and Piper guys are approaching nowhere near
that fast, but they require far more runway.
This is called "the real world" and it's important to live in it, as opposed to some
nostalgic fantasy world.
And, you can be sure that I don't abuse the hardware. Guess who is paying
for it, and spinning the wrenches on it.
The days of pilots having anywhere near competent stick & rudder skills
are long gone. As I said, the worst pilot I ever issued an L39 type rating to,
was a retired AC captain. The rest of the guys out there don't even fly as
well as he does, so you have to add the x2 correction factor to the Flight
Manual "fantasy numbers". This is what I have learned.
That make me either a BAD PERSONâ„¢ or a PUSSYâ„¢. I'm not sure which.
Maybe both?
All I know for sure, is that I have learned over many decades that people
that shit on me either don't fly, or they're going to be dead soon.
Either way, their opinion doesn't really matter much, does it?
#TCInspectorsHaveMagicPowers
Back in the real world, the most marginal candidate I ever signed off
for an L39 type rating was a retired Air Canada pilot. He had all the
hours. His ATP had all the types from flying up north - he had his ticket
punched. I figured he must know what he was doing, right?
But, he liked to come in fast, and land the L39 half-way down the 4,000
foot runway and lock up the brakes. This is a common error I see with
pilots these days - they approach much too fast, "for safety". Sigh.
Ok, but that means that they will never be able to obtain the hopelessly
optimistic book numbers. So, I suggest adding a correction factor of x2.
At my current home airport, there is a very long runway (to me - 5,200 feet)
and a "short runway" (2700 feet). Every time I am there flying the Pitts solo,
the Cessna and Piper pilots insist on using the 5200 foot runway and I am
using (solo) the short runway in the S-2B. It's fucking hilarious.
I routinely make the half-way turnoff after landing on the "short" runway for
taxiway Q which is 1300 feet, and I approach long final at 180 mph, then
160 mph, then 140 mph, then 120 mph short final, then touchdown at 100 mph.
Needless to say, the Cessna and Piper guys are approaching nowhere near
that fast, but they require far more runway.
This is called "the real world" and it's important to live in it, as opposed to some
nostalgic fantasy world.
And, you can be sure that I don't abuse the hardware. Guess who is paying
for it, and spinning the wrenches on it.
The days of pilots having anywhere near competent stick & rudder skills
are long gone. As I said, the worst pilot I ever issued an L39 type rating to,
was a retired AC captain. The rest of the guys out there don't even fly as
well as he does, so you have to add the x2 correction factor to the Flight
Manual "fantasy numbers". This is what I have learned.
That make me either a BAD PERSONâ„¢ or a PUSSYâ„¢. I'm not sure which.
Maybe both?
All I know for sure, is that I have learned over many decades that people
that shit on me either don't fly, or they're going to be dead soon.
Either way, their opinion doesn't really matter much, does it?
#TCInspectorsHaveMagicPowers
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Eric Janson
- Posts: 412
- Joined: Tue Jul 14, 2015 10:31 am
Just a few comments from the Airline world.
For years we used airbus numbers for landing which were obtained by test Pilots slamming the aircraft on the runway from 50' then giving maximum manual braking. We don't operate like this so the numbers are not realistic.
Airbus updated these figures to more accurately reflect real world operations (the landing distances increased by about 30%).
By law we have to add a 15% margin to these figures - except in an emergency.
A few years ago I was flying out of an airport with an MSA of 12000'. I was climbing out at minimum clean speed (best angle) until 12000' then accelerating to a cruise climb clear of terrain. The next day another Captain looked at the predictions in the computer and saw we would clear a 12000 restriction by 6000' so she just flew the normal climb profile. I was watching from the jumpseat and instead of the predicted 6000 we only had 2500 of clearance. Old airframe with lots of extra drag from patches and missing seals and engines not developing rated power will do this. I'll keep climbing at minimum clean speed thanks!
I always caution people not to accept climb restrictions with the aircraft because 9/10 you won't make it - I'm amazed at how just about everyone blindly accepts a computer prediction. Even people with more experience on the aircraft than me.
If you can't make the climb restriction at the last minute you cause all kinds of problems for ATC - I always tell them "unable" and try to get an extra 40 miles or so to climb.
My record is 49 minutes to 30000 on an ISA +20 day. The aircraft just wouldn't climb above 28000'.
For years we used airbus numbers for landing which were obtained by test Pilots slamming the aircraft on the runway from 50' then giving maximum manual braking. We don't operate like this so the numbers are not realistic.
Airbus updated these figures to more accurately reflect real world operations (the landing distances increased by about 30%).
By law we have to add a 15% margin to these figures - except in an emergency.
A few years ago I was flying out of an airport with an MSA of 12000'. I was climbing out at minimum clean speed (best angle) until 12000' then accelerating to a cruise climb clear of terrain. The next day another Captain looked at the predictions in the computer and saw we would clear a 12000 restriction by 6000' so she just flew the normal climb profile. I was watching from the jumpseat and instead of the predicted 6000 we only had 2500 of clearance. Old airframe with lots of extra drag from patches and missing seals and engines not developing rated power will do this. I'll keep climbing at minimum clean speed thanks!
I always caution people not to accept climb restrictions with the aircraft because 9/10 you won't make it - I'm amazed at how just about everyone blindly accepts a computer prediction. Even people with more experience on the aircraft than me.
If you can't make the climb restriction at the last minute you cause all kinds of problems for ATC - I always tell them "unable" and try to get an extra 40 miles or so to climb.
My record is 49 minutes to 30000 on an ISA +20 day. The aircraft just wouldn't climb above 28000'.
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John Swallow
- Posts: 319
- Joined: Fri Jun 03, 2016 1:58 pm
Eric: company for whom I worked in NB had a HS 125 (700 series); it ran out of poop fast if above ISA. On making treks for Florida, many flights were capped at FL 290 until enough fuel burned off to make another 4000 feet...
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Eric Janson
- Posts: 412
- Joined: Tue Jul 14, 2015 10:31 am
@John
Sounds like you were thrust limited - A340 is the same.
We were dealing with airspace issues - by climbing to FL300 we could just get to FL320 before entering Oceanic airspace.
FL280 would have lasted for at least 4 hours.
Big difference in fuel burn in the 2 scenarios.
We used to operate these flights on a re-dispatch flightplan - we needed every kilo of fuel. Great learning experience in flightplanning and performance.
Sounds like you were thrust limited - A340 is the same.
We were dealing with airspace issues - by climbing to FL300 we could just get to FL320 before entering Oceanic airspace.
FL280 would have lasted for at least 4 hours.
Big difference in fuel burn in the 2 scenarios.
We used to operate these flights on a re-dispatch flightplan - we needed every kilo of fuel. Great learning experience in flightplanning and performance.
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