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Posted

Hello folks!  So I am planning to fly to Santa Fe NM in a few weeks.  Scoping out density altitudes which are as expected, hot and high.  They have 3 nice big runways there so no problem right?

Seems like I should be able to be more precise than that.

Surely someone made a table or a chart that shows how many feet a runway needs to grow at various density altitudes.  Like grow factor y as the dependent variable a function of density altitude x.

E.g. right now at KSAF I see the density altitude is 9217'.   SO there are two 6300 ft runways and one 8366' runway.  Yes yes I know those are plenty big - but I am asking an empirical question perhaps more useful for other places.  So say I want to land at the 6300ft runway in 9217' density altitude conditions - is that equivalent to landing in a ???? runway?  4500' at sea level density altitude?  Anyway how do I do this calculation?

Posted
15 minutes ago, aviatoreb said:

Anyway how do I do this calculation?

Subscribe to ForeFlight Performance Plus.  In the rocket, you'd probably be safe using Bravo T/O numbers, right?  Heck, it's probably not that far off the Acclaim numbers since those are for the 280HP version.

Lemme know if you'd like the Acclaim T/O chart from the POH.

-dan

image.png.10a2bbe8c1a65a28c72fcbf23bacf810.png

Posted
21 minutes ago, aviatoreb said:

Hello folks!  So I am planning to fly to Santa Fe NM in a few weeks.  Scoping out density altitudes which are as expected, hot and high.  They have 3 nice big runways there so no problem right?

Seems like I should be able to be more precise than that.

Surely someone made a table or a chart that shows how many feet a runway needs to grow at various density altitudes.  Like grow factor y as the dependent variable a function of density altitude x.

E.g. right now at KSAF I see the density altitude is 9217'.   SO there are two 6300 ft runways and one 8366' runway.  Yes yes I know those are plenty big - but I am asking an empirical question perhaps more useful for other places.  So say I want to land at the 6300ft runway in 9217' density altitude conditions - is that equivalent to landing in a ???? runway?  4500' at sea level density altitude?  Anyway how do I do this calculation?

You turbo guys don’t have to worry about this part as much, but us NA guys also need to consider what happens to our climb rate.  Yes, that 8300’ runway is plenty good, but how does that 200fpm climb rate look in the valley?

  • Like 3
Posted

Your POH has all the performance charts. Santa Fe is not a problem airport. It isn’t in the mountains it is on the flat lands. Easy in and easy out.

If you are coming from New York, fly direct to SAF, when you come to the first mountain, fly around the left side of it and you will be at the airport.

  • Like 1
Posted
43 minutes ago, aviatoreb said:

Hello folks!  So I am planning to fly to Santa Fe NM in a few weeks.  Scoping out density altitudes which are as expected, hot and high.  They have 3 nice big runways there so no problem right?

Seems like I should be able to be more precise than that.

Surely someone made a table or a chart that shows how many feet a runway needs to grow at various density altitudes.  Like grow factor y as the dependent variable a function of density altitude x.

E.g. right now at KSAF I see the density altitude is 9217'.   SO there are two 6300 ft runways and one 8366' runway.  Yes yes I know those are plenty big - but I am asking an empirical question perhaps more useful for other places.  So say I want to land at the 6300ft runway in 9217' density altitude conditions - is that equivalent to landing in a ???? runway?  4500' at sea level density altitude?  Anyway how do I do this calculation?

You might be looking for a Koch chart?

https://www.takeofflanding.com/

 

  • Like 2
Posted
30 minutes ago, N201MKTurbo said:

Your POH has all the performance charts. Santa Fe is not a problem airport. It isn’t in the mountains it is on the flat lands. Easy in and easy out.

If you are coming from New York, fly direct to SAF, when you come to the first mountain, fly around the left side of it and you will be at the airport.

I don't think the Rocket STC came with full t/o ldg tables

Posted
14 minutes ago, exM20K said:

I don't think the Rocket STC came with full t/o ldg tables

If you use the original 231 performance tables, I think you can safely assume it will out perform that.

Posted
5 minutes ago, N201MKTurbo said:

If you use the original 231 performance tables, I think you can safely assume it will out perform that.

take off: yes.  Landing? dunno.  But that is the extent of the performance notes in the STC IIRC.

Same deal for the 310HP Acclaim.  

-dan

  • Like 1
Posted
2 hours ago, exM20K said:

Landing def a bigger deal:

Total Distance
3461'
Ground Roll
2218'

 

ForeFlight has that too with Performance Plus…

I use a 1.5 Safety factor for Takeoff and Landing

-Don

Posted
6 hours ago, exM20K said:

take off: yes.  Landing? dunno.  But that is the extent of the performance notes in the STC IIRC.

Same deal for the 310HP Acclaim.  

-dan

Exactly - I was thinking landing too.

Posted

This is mostly nonresponsive to your question, but...  For every departure from a high and/or hot airport, I use a script that @Bob - S50 built.  It produces a nice little calculated output screen (example attached with a bunch of fake numbers plugged in).  The script has a lot of tunable parameters that you can customize for your a/c, and once the parameters are set, it's very easy to calculate performance for your intended departure in just a minute or two.

https://mooneyspace.com/topic/8475-takeoff-and-landing-calcs/

I'm a gearhead and I enjoy seeing how the sausage is made, so a tunable script that I can run locally is a big win for me.  I have no clue whether something similar exists for high/hot landing calculations.

m20j-takeoff-calculator.png

  • Like 1
Posted

Totally different than your question Eric, I was in New Mexico a couple years ago, takeoff wasn’t an issue, landing on the hot runway was difficult to get the Bravo at a good speed to land because of the heat rising off the runway therefore floating forever. I believe there’s a technique on a high hot runway. The disconcerting thing was the turbulence which was extreme. Being a northeaster person we’re not accustomed to that environment. You’ll see more of our beautiful country.

D

  • Like 2
Posted
15 hours ago, exM20K said:

take off: yes.  Landing? dunno.  But that is the extent of the performance notes in the STC IIRC.

Same deal for the 310HP Acclaim.  

-dan

That's the source of my worry - I am darn sure I can take off from whatever I can land on.  I am not actually worried I won't be able to land on a 6000 ft runway even at 9000ft of altitude - but I am surprised to realized this is an important piece of aviation operations info I do not know how to compute - when I am thinking ground roll on landing - what should I consider a 6000ft runway at 9200ft pressure altitude to be like vs what unknown to me length at sea level pressure altitude - half?  Should I expect touch down speed is so high (True air speed) if I am spot on flying by IAS and angle of attack that I will have so much kinetic energy so as to roll much longer and it will be like...what - a 3000ft runway?  Anyway I figure this is something I REALLY should know how to do - also not to mention - what if ... knock on wood ... there is need for an emergency landing somewhere else?  I (we) should really know how to do this computation.

Mostly - computations aside - rule of thumb - the rocket has an easy time flying out of whatever it can land into.  Especially with just me on board - even with full fuel.

Posted
10 minutes ago, Danb said:

Totally different than your question Eric, I was in New Mexico a couple years ago, takeoff wasn’t an issue, landing on the hot runway was difficult to get the Bravo at a good speed to land because of the heat rising off the runway therefore floating forever. I believe there’s a technique on a high hot runway. The disconcerting thing was the turbulence which was extreme. Being a northeaster person we’re not accustomed to that environment. You’ll see more of our beautiful country.

D

Thanks - that is VERY useful intel.

How hot?

So that's what - local heat bubbling/rising off a hot tarmac?  Is that effect still there if there is wind or does it then mostly convert to standard turbulence in windy conditions considerations?

Posted
20 hours ago, aviatoreb said:

Hello folks!  So I am planning to fly to Santa Fe NM in a few weeks.  Scoping out density altitudes which are as expected, hot and high.  They have 3 nice big runways there so no problem right?

Seems like I should be able to be more precise than that.

Surely someone made a table or a chart that shows how many feet a runway needs to grow at various density altitudes.  Like grow factor y as the dependent variable a function of density altitude x.

E.g. right now at KSAF I see the density altitude is 9217'.   SO there are two 6300 ft runways and one 8366' runway.  Yes yes I know those are plenty big - but I am asking an empirical question perhaps more useful for other places.  So say I want to land at the 6300ft runway in 9217' density altitude conditions - is that equivalent to landing in a ???? runway?  4500' at sea level density altitude?  Anyway how do I do this calculation?

Doesn’t a koch chart give you most of what you’re looking for?

Posted
20 hours ago, aviatoreb said:

Hello folks!  So I am planning to fly to Santa Fe NM in a few weeks.  Scoping out density altitudes which are as expected, hot and high.  They have 3 nice big runways there so no problem right?

Seems like I should be able to be more precise than that.

Surely someone made a table or a chart that shows how many feet a runway needs to grow at various density altitudes.  Like grow factor y as the dependent variable a function of density altitude x.

E.g. right now at KSAF I see the density altitude is 9217'.   SO there are two 6300 ft runways and one 8366' runway.  Yes yes I know those are plenty big - but I am asking an empirical question perhaps more useful for other places.  So say I want to land at the 6300ft runway in 9217' density altitude conditions - is that equivalent to landing in a ???? runway?  4500' at sea level density altitude?  Anyway how do I do this calculation?

4 minutes ago, Ragsf15e said:

Doesn’t a koch chart give you most of what you’re looking for?

I came across this site some time ago and bookmarked it as we fly into KPSO in CO quite a bit and it is at 7,663' elevation. You can either put in an airport identifier and it will pull the current weather, or just fill in the blanks.

https://www.takeofflanding.com/

  • Like 2
  • Thanks 1
Posted
1 hour ago, Skates97 said:

I came across this site some time ago and bookmarked it as we fly into KPSO in CO quite a bit and it is at 7,663' elevation. You can either put in an airport identifier and it will pull the current weather, or just fill in the blanks.

https://www.takeofflanding.com/

It seems as if the Koch table should do everything I want - I was unaware of it when I first started this thread - but Im not yet confident Im using it correctly.

If say I put 6349ft (KSAF altitude) as pressure altitude (assuming standard?) and I put 83F current temp (which is showing density altitude of 9088 from other means) and I get 6000 ft is like 2110ft equivalent at sea level - OUCH - Am I doing that correctly?  that's worse than I guessed and I am glad I am asking this question.

Posted
10 minutes ago, aviatoreb said:

It seems as if the Koch table should do everything I want - I was unaware of it when I first started this thread - but Im not yet confident Im using it correctly.

If say I put 6349ft (KSAF altitude) as pressure altitude (assuming standard?) and I put 83F current temp (which is showing density altitude of 9088 from other means) and I get 6000 ft is like 2110ft equivalent at sea level - OUCH - Am I doing that correctly?  that's worse than I guessed and I am glad I am asking this question.

probably applicable only to NA aircraft.  Your turbo gives only a few poops about DA on takeoff.  Even no wind and MTOW, the 280HP acclaim is at 3400 ish ft over 50'

 

 

Acclaim Type S 50ft TO.pdf

  • Like 2
Posted
7 hours ago, aviatoreb said:

Thanks - that is VERY useful intel.

How hot?

So that's what - local heat bubbling/rising off a hot tarmac?  Is that effect still there if there is wind or does it then mostly convert to standard turbulence in windy conditions considerations?

Weekend before last I landed our J at SAF on rwy 20 with winds 230@18G30 , temperature 29C, and density altitude 9200'.  So busy dealing with gusty crosswind component that the 8000' runway seemed immense.

RJ's and 737s use that runway.  Runway length is a non-issue for a piston single.

Have a good trip.

  • Like 1
Posted
11 hours ago, Skates97 said:

I came across this site some time ago and bookmarked it as we fly into KPSO in CO quite a bit and it is at 7,663' elevation. You can either put in an airport identifier and it will pull the current weather, or just fill in the blanks.

https://www.takeofflanding.com/

That site is awesome. I carry one of those laminated on the back of my checklist, but the interactive site is nice.  I wish it let you put in sea level climb rate and applied the correction it’s coming up with.  I did a 4800’ elevation at 85 degrees f and it says 67% reduction in climb.  So maybe 350fpm left of my normal 1000fpm.

  • Like 1
Posted
On 6/28/2023 at 7:52 AM, Danb said:

Totally different than your question Eric, I was in New Mexico a couple years ago, takeoff wasn’t an issue, landing on the hot runway was difficult to get the Bravo at a good speed to land because of the heat rising off the runway therefore floating forever. I believe there’s a technique on a high hot runway. The disconcerting thing was the turbulence which was extreme. Being a northeaster person we’re not accustomed to that environment. You’ll see more of our beautiful country.

D

A technique for a hot runway and just floating in general is to reach over and flip the flap switch up, as they come up she will settle and land, you will probably have to add a little pitch up, but at a higher speed than it would with full flaps of course, but it stops the floating, waiting for the heat bubble to burst and a thump down landing.

‘I’ve not tried this with my electric flap Mooney but it works well for the hydraulic ones and I cant see any reason it wouldn’t for electric.

Just haven’t had the need down here, grass of course you don’t get that huge heat like we did off of asphalt on a near windless afternoon in Tx, yes I know near windless in Tx in Summer is very rare,

Posted
10 minutes ago, A64Pilot said:

A technique for a hot runway and just floating in general is to reach over and flip the flap switch up, as they come up she will settle and land, you will probably have to add a little pitch up, but at a higher speed than it would with full flaps of course, but it stops the floating, waiting for the heat bubble to burst and a thump down landing.

‘I’ve not tried this with my electric flap Mooney but it works well for the hydraulic ones and I cant see any reason it wouldn’t for electric.

Just haven’t had the need down here, grass of course you don’t get that huge heat like we did off of asphalt on a near windless afternoon in Tx, yes I know near windless in Tx in Summer is very rare,

It works well for my electric flap C, at least the one time I was floating along a 2000' grass strip at 3' agl. As I passed midfield heading towards the concrete plant's gravel pile, I raised the flaps--the tail dipped and the wheels rolled, easily stopping with light braking to taxi to parking. 

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