Teach me why I listen to Turboprop drivers always discussing airspeed.

[siouxicide]

Recommended reading for all that don't understand TAS:
True airspeed defined Check out the second sentence.

 

[cvsfly]

Hey...

Someone please teach me why I listen to Turboprop drivers always discussing airspeed.

.....

GS matters to me when I'm flight planning before a flight and during the flight. TAS matters to me if I was discussing performance of a flight after the fact. Talking about what GS you made with someone after the fact - other than bragging rights for a tailwind or aggravation of the fuel bill for a headwind - means very little beyond that. It tells me nothing about the aircraft performance unless I know the exact winds aloft you had. You could of had the power pulled back truing at 200 kts with a 50kt tailwind or you could be at normal cruise truing at 270 kts with a 20kt headwind. Very relative number is GS. TAS with no wind = GS.

 

[kingairyahoo]

bah humbug...its all relative

how heavy are ya? how far are you going? whats ATC gonna do to ya? is it an owner flight or a charter leg? what are the temps? what are the winds doing at the anticipated flight levels? are you taking AK47 rounds from the top of hills while trying to gain altitude leaving FOB Ripley, forcing you to fly down the valley in an underpowered B100 with 10 dam warrant officers onboard who have nothing better to do than overload your airplane...thread creep

back on topic...www.fltplan.com, for the win :beer:

 

[hmmm]

Ummmm in real life if you cant understand the relationship between something as simple as tas and gs you really should rethink all that theoretical bull you learnt again...it might come in handy one day!

Don't need to say much to that.

Lets see so far had 6 engine failures, a cockpit fire, loss of 3 gens 4 nose gear malfunctions, loss of two hydraulics sysytems and

oh never mind I must not be as experienced.

Oh by the way... Why are we talking about TAS I never asked about that.

Indicated, True what ever. The only thing that matters is the one on the dial or tape and how fast your moving toward destination compared to fuel burn.

Oh my gosh without TAS the airplanes going to fall out of the sky.

Yeah Ok We are sure you know all about it and without it nobody can handle their job.

Therefore I guess without you the world would stop spinning.

Oh and isn't fltplan.com wonderful!!!

 

[guido411]

I think I'm going to have to take issue with that. I don't have much time in King Airs, but the Metros and Jet Streams that I flew had tons to gain by climbing.

First, I can rarely reach 100% torque on any given day. So, flying at 100% power just isn't an option.

I have the opposite of your experience and have only flown turboprops with PT-6s. Every single one of them are able to make 100% Tq at SL because they are "flat- rated". They may be capable of producing twice as much HP as they are rated for (thermodynamic power) but are limited to a lesser amount.

If the engine was not flat-rated it would only make 100% rated power at SL. The Pratt TP airplanes I have flown have all maintained 100% Tq up to a certain altidue where either the power levers had no travel left or temperature (ITT) was at it's max allowable for climb/cruise. THAT is the optimum altitude for that particular airplane when referencing TAS (fuel flow is another consideration that only the pilot [or owner] can weigh the imprtance of).

So I say again slightly re-stated, the best altitude (if you want to brag about how fast your PT6 soot-streaker goes) is the highest altitude attainable where your engine is still producing 100% of it's rated power.

 

[siouxicide]

Since you started thumping your chest, I just had to:

Now I have been around all sorts of airplanes forever. Worked on just about everything including being a jet and turboprop engine overhaul guy and inspector

Lets see so far had 6 engine failures, a cockpit fire, loss of 3 gens 4 nose gear malfunctions, loss of two hydraulics sytems

Coincidence?

As a pilot I care about is my speed across the ground depending on the altitude in still air....

That's the definition of True Airspeed, more or less. Because you spelled it out the hard way, it tells me you didn't know that.

The only thing that matters is the one on the dial or tape....

And that would be Indicated Airspeed. Why the contradiction?

 

[hmmm]

oh boy

 

[Morettis]

I'm going to second that the best altitude isn't always the highest you can get to.

The Metro I fly gets the best TAS at FL190 and FL200. I also get a huge fuel drop from 17,000 to FL190 but virtually no drop above FL200. I can go to FL300 (if I had RVSM) but I lose about 30 kTAS.

So, when you hear KA pilots talking airspeed (guessing its TAS) at certain altitudes, they are just comparing their best performance.

Last I checked, the book says the best TAS for a metro is in the 10-15k range depending on temperature and weight. Best TAS comes at the highest altitude that you can hold the barber pole.

 

[ksu_aviator]

Last I checked, the book says the best TAS for a metro is in the 10-15k range depending on temperature and weight. Best TAS comes at the highest altitude that you can hold the barber pole.

If all you are worried about is TAS, than you are probably right. But I'm using numbers for best fuel burn to TAS ratio.

 

[woog315]

With winds calm, I get about 260K TAS from 12k - ~22k at 100%rpm and max torque, obviously i head up to 220 for the increased fuel savings. Also, I don't agree with the guy who said he sees little fuel savings above 190, I drop an extra 75-125lbs/hr going from 190 to around 230 with no ground speed reduction

edit: it probably depends on how long your legs are if climbing above 190 is worth it as the metro tends to bog down around there. I'm frequently on 4-5hr legs so it's worth it for me.

 

[lawfly]

Okay, as an "outsider" to this thread, it strikes me as mentionable that the original post is headlined: "teach me..."
Then, when people try to do just that, the original poster becomes defensive and starts talking about the number of engine failures, etc., that he has experienced. My observation/suggestion is this: It's better to say TAS than "airspeed across the ground depending on altitude in still air". ("Depending on altitude" impliedly taking temperature into account.) And if the more laborious description is used, then openness to its general equivalence to TAS should be entertained. Don't say "teach me" if you are not open to such input. The poster who said he had teaching/instructional experience acted reasonably in responding to a "teach me" post.

 

[ksu_aviator]

With winds calm, I get about 260K TAS from 12k - ~22k at 100%rpm and max torque, obviously i head up to 220 for the increased fuel savings. Also, I don't agree with the guy who said he sees little fuel savings above 190, I drop an extra 75-125lbs/hr going from 190 to around 230 with no ground speed reduction

edit: it probably depends on how long your legs are if climbing above 190 is worth it as the metro tends to bog down around there. I'm frequently on 4-5hr legs so it's worth it for me.

I'm lucky. My Metro has brand spanking new power plants. Not just out of hot section. Actual new engines! So, My climb from SL to 190 is less than 19 minutes in Texas during the summer at MTOW. However, above 21 I peter out pretty bad. To me, it if it is 250 NM or more, it is worth going to 19/20.

 

[satpak77]

I always flew the King Air 350 at 25 and 26,000 on any long cross country.

 

[CaptSeth]

As a pilot, you should know that if you are measuring an aircraft's performance you will use TAS.

If you are concerned about buffet margins and safe speeds to be flown, you should be looking at IAS.

If you are interested in conditions on a given flight as determined by winds and temperatures aloft, you are looking at GS.

A conversation at the FBO that appeared to be a discussion of performance was appropriate, however boring it may have been, in that TAS was used as the measurement. This is private pilot material.

Hmmm - are you a pilot?

 

[hmmm]

Okay, as an "outsider" to this thread, it strikes me as mentionable that the original post is headlined: "teach me..."
Then, when people try to do just that, the original poster becomes defensive and starts talking about the number of engine failures, etc., that he has experienced. My observation/suggestion is this: It's better to say TAS than "airspeed across the ground depending on altitude in still air". ("Depending on altitude" impliedly taking temperature into account.) And if the more laborious description is used, then openness to its general equivalence to TAS should be entertained. Don't say "teach me" if you are not open to such input. The poster who said he had teaching/instructional experience acted reasonably in responding to a "teach me" post.

If u re read the original post it said paraphrase people always discussing airspeed..... I didn't say what kind of airspeed. How bout you wipe your azz with you lamentation..... If u would like to discuss it you can have my phone address and airport ident and you can stop by in person or I can pass ride to see you about it when I have time. I don't stand here behind secret screen names. But right now I have to get out to the hangar and replace a fuel valve while you spen time trying to polish yourself.

 

[hmmm]

Hmmm - are you a pilot?

What do you think Seth?

You are one that couldn't read very well elsehwere so lets leave it at that. People come here asking or looking for opinions but other people seem to only be looking for the next greatest thing to grab on to so they can stand up on their soap box and proclaim for themselves they know it all and without knowing everything that they think they know and beleive others don't, the world would stop spinning.

As for me I grew up in this industry. I'm sure others have to. I haven't seen it all. I know others have been into ends of the business in depth that I haven't.

But when it come to me asking why do I hear King Air drivers always talking about airspeed in cruise its just that... asking why do King Air drivers seem to be always talking about airspeed..... not TAS.... not the definition of TAS...... not Indicated..... just the word "airspeed" and have only heard that around King Air Drivers.

I heard some really good answers about it from people you could tell were actual aviators in the business... then I heard people who take things and run with it half cocked and others just trying to prove they are gods gift to the person in the mirror..... Seth You are somewhat included... you do listen.... but not good enough.

Maybe I don't either..... But lets leave it at that.... you were help to me elsewhere as devils advocate but you don't really read completely the question.

Others Thankyou.

 

[cvsfly]

edit.....

 

[cvsfly]

I can only imagine the "airspeed" you heard KA pilot's talking about was TAS. I think that is what the people here are assuming they are referring to TAS and don't understand your issue with these "KA pilots". TAS or Mach speed is probably the only appropriate speed to discuss after the flight among peers who are interested in your performance and perhaps comparing airframes and engine health. You really have no control what GS you will get without modifying your "normal cruise" profile on a daily basis. To "discuss" GS is an exercise in futility since your GS will be wildly different on any given day. Of course with an increasing headwind with altitude you may choose a lower altitude for better GS assuming you can afford the increased fuel flow vs speed gained and reverse for tailwind. www.fltplan.com wind matrix is wonderful.

"As a pilot I care about is my speed across the ground depending on the altitude in still air first then as affected by the winds compared to my fuel flow.

Speed across the ground is what matters to me and in the jets I was on (DC-8, CRJ & 737) the higher we got the faster we go across the ground... and lower the fuel flow.

As the airspeed dwindles as we go higher per profile.... who cares that the airspeed is lower.... we are going 460kts across the ground at maybe 275 kts indicated on most jets.

I hear guys on KA's more than once for example say "we usually run FL230 where we getting our best airspeed of about 272 kts.

I want to ask them what is there groundspeed at that FL and why do they care so much about airspeed in cruise compared to ground speed and what ground speed do they get if they climb higher which is what matters getting the burn per hour down and the ground speed per hour up."

This last part is probably the confusing part assuming that the "airspeed" discussion is TAS. I think your assumption is they are talking IAS.

The KA at FL230 with an "airspeed" of 272 kts is most likely a BE-200 with a TAS of 272. A straight 200 usually gets its best TAS vs fuel flow at 210-230 and a B200 probably 220-240 with no mods. Yes you can reduce fuel flow the higher you go (limited by RVSM capability perhaps), but your TAS will drop off (usually more substantially than fuel flow). Most Turbo-prop people are flying the best speed for the lowest fuel burn. When fuel goes back to $8.00 + gal we all may be pulling back the power or going higher despite the "slower GS" and higher airframe times. Then again, higher in a TP is not always better due to pressurization, turbulence, etc. But again you know all of this. It was just a confusing mix of assumptions, terms, and sentence structure in the original post.