Heard on the air...

[Hank]

11 hours ago, A64Pilot said:

your right, save fuel thereby increasing range. I misspoke.

I’m not saying your wrong so much as I’m saying often that “best advice” given on the internet often is, like for instance to keep from losing any speed LOP, simply increase MP until your speed is recovered. Sounds good but often isn’t possible.

I’m flying WOT now, how do I increase MP?

Maybe it’s just me and the people I hang around, but when traveling, the throttle is opened on takeoff, and not touched until the let down at destination. Altitude reduces the throttle for me.

Must be for Brand C & P who typically fly lower altitudes at reduced throttle settings. Then again, many of them don't have constant speed props or MP gages, so maybe it's a different group?

[jlunseth]

On 10/25/2022 at 5:05 PM, A64Pilot said:

your right, save fuel thereby increasing range. I misspoke.

I’m not saying your wrong so much as I’m saying often that “best advice” given on the internet often is, like for instance to keep from losing any speed LOP, simply increase MP until your speed is recovered. Sounds good but often isn’t possible.

I’m flying WOT now, how do I increase MP?

Maybe it’s just me and the people I hang around, but when traveling, the throttle is opened on takeoff, and not touched until the let down at destination. Altitude reduces the throttle for me.

 

Well, you’re in a conversation with some people who have turbos and some who don’t. With turbos we can do that, increase MP beyond ambient. With NAs you can’t, it’s that simple. Ops for the two types are definitely different. Not arguing that one is superior to the other, just different. If you are operating WOTLOPSOP in your NA from takeoff to landing then there is certainly nothing wrong with your way of operating your aircraft, and probably everything right about it.

When I took my lessons in Skyhawks and Warriors it was standard procedure to reduce MP to “square,” so RPM’s were 2500, MP had to be 25”. There was no EGT in those planes, we were taught to lean back to roughness then forward until smooth and that was that. Ideas have definitely changed since then, on the other hand, those were mostly planes that could not fly LOP anyway. Carbureted and with school plane type maintenance. 

[Will.iam]

On 10/25/2022 at 7:11 AM, A64Pilot said:

I’ve never understood why so many believe you can increase range in a headwind by speeding up, when about all you can really do is sit back and try not to keep looking at your ground speed.

I believe our speed range is so small that it doesn’t make as much of a difference but one time on a mission we had to give extra gas that was  not scheduled due to weather and when we setup to return to base we needed 25k normally due to it being an island destination. When we climbed up into the flight levels there was a 200kt headwind. Our best range was calculated at 215kts and at that speed we would have ran out of gas before we got there but pushing it up to 315kts we got a waiver for the min 25k and made it back with 18k. It was a big lesson about how going faster in a headwind actually saved us gas instead of just calculating best range without regard to wind. The differences are much smaller when you have smaller speed window. 

[A64Pilot]

6 hours ago, Will.iam said:

I believe our speed range is so small that it doesn’t make as much of a difference but one time on a mission we had to give extra gas that was  not scheduled due to weather and when we setup to return to base we needed 25k normally due to it being an island destination. When we climbed up into the flight levels there was a 200kt headwind. Our best range was calculated at 215kts and at that speed we would have ran out of gas before we got there but pushing it up to 315kts we got a waiver for the min 25k and made it back with 18k. It was a big lesson about how going faster in a headwind actually saved us gas instead of just calculating best range without regard to wind. The differences are much smaller when you have smaller speed window. 

You were flying turbines. Turbines suck at part throttle efficiency, reason why ah AH-64’s max range airspeed is 130 ish kts. Drag is way up, but the engine increase in efficiency is greater than the drag increase, but Mooney’s aren’t turbines.

I too was stuck with not enough fuel to destination in France, two AH-64’s, a couple of OH-58’s a couple of Brit’s in Lynx’s and the Frenchman that we had to follow changed destination in flight, we couldn’t speed up to max range as the French and the OH-58’s couldn’t keep up and we wouldn’t make it if we didn’t, pretty sure the Lynx’s  could have.

I transferred all fuel to the aft tank and shut down #1 engine as I knew one engine at high power was much more fuel efficient than two at half power. We made it, the other aircraft that wouldn’t shut down one didn’t and we had a hard time getting fuel to him. He ended up with a parking ticket, really.

But we don’t fly turbines, using foreflight I put in a couple of profiles, one at Carson’s speed, 120 kts and 6.5 GPH cause that’s a little more than I burn to get 120 kts

I’ve read Carson’s speed is 130% of max glide, so 90 x 1.3 = 120. I’ve not validated it, but it seems correct as I can squeeze 20 NMPG out in zero wind.

To go from home at 500’ with a 30 kt head wind would take 21.8 gallons of fuel to get to ATL, 309 NM. I burn 6 gph, but 6.5 ought to work, this is just redneck math anyway.

Then I plugged in 155 kts and 10.5 GPH, cause that’s what I read a Mooney J model’s realistic cruise is, to do that mythical flight to ATL with a 30 kt head wind would take 

25.7 gls of fuel. 

So I bumped the headwind to 50 kts, Carson’s speed which is now 70 kts ground is 27 gls of fuel

The 155 kt 10.5 gl per hour which is now 105 kts ground speed is now 30 gls.

I used 500 ft to keep from the climb and descent with mucking with it, so no climb really it’s all cruise

So I threw in a 70 kt headwind 

Carson’s speed is now 50 kt ground and burns 36 gls of fuel, the 155 cruise is now 85 kts ground, and interestingly burns 36 gls of fuel, so by this primitive reckoning, there is indeed a point that going faster may save fuel, but it’s into an over 70 kt headwind. I will never fly into a 70+ kt headwind, I never have even come close, forecasts aren’t perfect, but I’ve never seen one so wrong that I end up with 70+ kt headwind.

So, unless I’ve mucked this up, it’s theoretically possible, but not in any realistic flight profile, because I don’t know anyone stubborn enough to beat into an over 70 kt headwind.

Now to go back and fix my Foreflight

[Hank]

11 hours ago, A64Pilot said:

So, unless I’ve mucked this up, it’s theoretically possible, but not in any realistic flight profile, because I don’t know anyone stubborn enough to beat into an over 70 kt headwind.

Allow me to introduce myself. My wife and I burned a day's vacation because of PIREPs for icing in southern WV, and stayed an extra night with her parents at Ft. Bragg. That area was still ugly on Monday, so I flew west across NC at 3000 msl to GSP, holding 100-105 knots groundspeed. Then GSP-TYS required a climb to 6000 and speeds of 90 knots. Knoxville approach had me climb to 9000 to clear terrain. It was sunset, below freezing with many cloud tops, so I asked for 10,000 where groundspeed fell to 68 knots and very little effort to avoid the icy tops. As soon as we were clear of terrain, we came back down to 4000 and passed 100 knots again, and turned towards KLEX. I really wish I could remember the groundspeed after turning east at LEX for home in WV, but I was busy setting up for the approach.

The flight out was 2:20; the dogleg home in awful winds was one day late and 4:45, using 41 gallons. Sometimes you just have to fly in unfavorable winds . . . .

[A64Pilot]

22 minutes ago, Hank said:

Allow me to introduce myself. My wife and I burned a day's vacation because of PIREPs for icing in southern WV, and stayed an extra night with her parents at Ft. Bragg. That area was still ugly on Monday, so I flew west across NC at 3000 msl to GSP, holding 100-105 knots groundspeed. Then GSP-TYS required a climb to 6000 and speeds of 90 knots. Knoxville approach had me climb to 9000 to clear terrain. It was sunset, below freezing with many cloud tops, so I asked for 10,000 where groundspeed fell to 68 knots and very little effort to avoid the icy tops. As soon as we were clear of terrain, we came back down to 4000 and passed 100 knots again, and turned towards KLEX. I really wish I could remember the groundspeed after turning east at LEX for home in WV, but I was busy setting up for the approach.

The flight out was 2:20; the dogleg home in awful winds was one day late and 4:45, using 41 gallons. Sometimes you just have to fly in unfavorable winds . . . .

Not now, I would have landed and gone another day, or more likely just waited another day. unless it’s a short flight. Four hours I guess we would have continued cause that’s not that long. But here’s the thing 70 kts is the break even point on my Foreflight exercise, to get anything significant it would take likely a 90 kt headwind, and that’s really nuts.

But you knew the winds sucked,  A few times when I was a kid and Wx was bad we left the airplane wherever and flew back commercial and my Father went back to get it.

I did fly in very strong winds once, had a 200 kt ground speed on the Maule, we didn’t come back that day, next day was calm. Biggest problem was taxing once on the ground.

If caught in heavy headwinds I’m going full throttle ROP and buying the gas, but I don’t convince myself that I’m saving fuel by doing so, just saving time.

 

[Will.iam]

14 hours ago, A64Pilot said:

You were flying turbines. Turbines suck at part throttle efficiency, reason why ah AH-64’s max range airspeed is 130 ish kts. Drag is way up, but the engine increase in efficiency is greater than the drag increase, but Mooney’s aren’t turbines.

I too was stuck with not enough fuel to destination in France, two AH-64’s, a couple of OH-58’s a couple of Brit’s in Lynx’s and the Frenchman that we had to follow changed destination in flight, we couldn’t speed up to max range as the French and the OH-58’s couldn’t keep up and we wouldn’t make it if we didn’t, pretty sure the Lynx’s  could have.

I transferred all fuel to the aft tank and shut down #1 engine as I knew one engine at high power was much more fuel efficient than two at half power. We made it, the other aircraft that wouldn’t shut down one didn’t and we had a hard time getting fuel to him. He ended up with a parking ticket, really.

But we don’t fly turbines, using foreflight I put in a couple of profiles, one at Carson’s speed, 120 kts and 6.5 GPH cause that’s a little more than I burn to get 120 kts

I’ve read Carson’s speed is 130% of max glide, so 90 x 1.3 = 120. I’ve not validated it, but it seems correct as I can squeeze 20 NMPG out in zero wind.

To go from home at 500’ with a 30 kt head wind would take 21.8 gallons of fuel to get to ATL, 309 NM. I burn 6 gph, but 6.5 ought to work, this is just redneck math anyway.

Then I plugged in 155 kts and 10.5 GPH, cause that’s what I read a Mooney J model’s realistic cruise is, to do that mythical flight to ATL with a 30 kt head wind would take 

25.7 gls of fuel. 

So I bumped the headwind to 50 kts, Carson’s speed which is now 70 kts ground is 27 gls of fuel

The 155 kt 10.5 gl per hour which is now 105 kts ground speed is now 30 gls.

I used 500 ft to keep from the climb and descent with mucking with it, so no climb really it’s all cruise

So I threw in a 70 kt headwind 

Carson’s speed is now 50 kt ground and burns 36 gls of fuel, the 155 cruise is now 85 kts ground, and interestingly burns 36 gls of fuel, so by this primitive reckoning, there is indeed a point that going faster may save fuel, but it’s into an over 70 kt headwind. I will never fly into a 70+ kt headwind, I never have even come close, forecasts aren’t perfect, but I’ve never seen one so wrong that I end up with 70+ kt headwind.

So, unless I’ve mucked this up, it’s theoretically possible, but not in any realistic flight profile, because I don’t know anyone stubborn enough to beat into an over 70 kt headwind.

Now to go back and fix my Foreflight

But what you might not realize is how much our small speed window effects when it’s better to go faster. 215 to 315 is almost a 50% speed increase 46.5% actually. To achieve that in a mooney, that you where flying carson’s speed of 120 would mean you would have to go 175.8. Not impossible, but would be max power if achievable in my airplane at least and a whole lot higher than 500 feet so not practical. I think you would find if you ran your experiment again with 120 to 175 speed difference it would not take as high of a head wind to make the difference. I. E. An Acclaim ultra would see some merit before a M20K model i would think. And a J model would be even less so as you are alt limited to 7k or below to get that fast. 

[0TreeLemur]

Anybody ever take the time to produce a set of power required curves for a Mooney at different altitudes?

[201er]

20 hours ago, A64Pilot said:

Carson’s speed is now 50 kt ground and burns 36 gls of fuel, the 155 cruise is now 85 kts ground, and interestingly burns 36 gls of fuel, so by this primitive reckoning, there is indeed a point that going faster may save fuel, but it’s into an over 70 kt headwind. I will never fly into a 70+ kt headwind, I never have even come close, forecasts aren’t perfect, but I’ve never seen one so wrong that I end up with 70+ kt headwind.

So, unless I’ve mucked this up, it’s theoretically possible, but not in any realistic flight profile, because I don’t know anyone stubborn enough to beat into an over 70 kt headwind.

Now to go back and fix my Foreflight

I don’t think anyone is coming expecting to make money slowing down but the cost penalty for going faster is reduced. You should add time and cost to your calculations to see what I mean.

In effect, if you calculate Carson’s speed in still air and assign it a dollar value, then increase it proportionate to the headwind, you’ll have a higher best bang for the buck in headwind speed instead of an aerodynamic speed.

Especially true when you factor in the hourly cost of airframe time, engine time, etc. Headwinds eat into those as well as fuel so you do get more back by speeding up.

[A64Pilot]

22 hours ago, 201er said:

I don’t think anyone is coming expecting to make money slowing down but the cost penalty for going faster is reduced. You should add time and cost to your calculations to see what I mean.

In effect, if you calculate Carson’s speed in still air and assign it a dollar value, then increase it proportionate to the headwind, you’ll have a higher best bang for the buck in headwind speed instead of an aerodynamic speed.

Especially true when you factor in the hourly cost of airframe time, engine time, etc. Headwinds eat into those as well as fuel so you do get more back by speeding up.

That’s all theoretical, fuel is my major expense and I expect there will be some time left on the engine for TBO when I’m done flying based on my age and time on the engine now. If I can fly until I’m 80, that’s 15 years and if I fly 100 hours a year, that’s 1500 hours, engine has about 500 on it now, and as most age they fly less. Fuel is my major expense followed by insurence as I don’t pay for maintenance labor, hangar rent, or a payment on the airplane, so that pretty much leaves fuel, oil and parts and insurence.

I understand the argument though, my Sister used to say as a Dentist she made xxx$ per hour, so it made no sense for her to do things that she could hire out for less than xxx per hour, it falls apart though because she wasn’t taking time off from work to do laundry or clean the house, it was just a way to justify being lazy.

But speeding up doesn’t save as much time as you think, I don’t almost ever fly Carson’s speed, or wide open ROP, usually if not traveling I’m at 8GPH and about 135 kts.

So in my case it’s 135 vs 155 kts. I’ve played with it and the difference in fuel milage isn’t bad at 135. 120 is just too slow most of the time for me.

For me speeding up and burning say 20% more fuel and saving 10% on time isn’t worth it. ( i just made up those numbers as math skills suck) but if someone is smart enough we are comparing 8 gph to 10.5 and 135 kts to 155 kts.

Besides I’m convinced the engine will last much longer at 60% power LOP than it will WOT and higher RPM ROP. If I’m right and I’m betting money that I am that extended life may well outweigh the slightly lower hours from flying hard. Lycoming is on record saying for max longevity fly at or below 65% power.

Bottom line I don’t think anyone really knows and anyone can (prove) anything if an assumption or two is accepted as being true, like the engine lasting longer at 60% power LOP for instance.

[Hank]

4 hours ago, A64Pilot said:

For me speeding up and burning say 20% more fuel and saving 10% on time isn’t worth it. ( i just made up those numbers as math skills suck) but if someone is smart enough we are comparing 8 gph to 10.5 and 135 kts to 155 kts.

Easy math, yaay!

135 knots ÷ 8 gph = 16.9 mpg

155 knots ÷ 10.5 gph = 14.8 mpg, or 14.8% faster and 12.4% more fuel.

[201er]

Demonstrated a bunch of pretty real world numbers in this example:

At today's gas prices, makes an even bigger difference. For example 1000nm trip with $8/gallon fuel:

145ktas@8.5gph vs 155ktas@10.0gph

0 wind: $469 in 6.9 hours or $520 in 6.5 hours, $51 to save 0.4 hours

50 knot headwind: $714 in 10.5 hours or $760 in 9.5 hours, $46 to save 1.0 hours

The stronger the headwind, the lower the premium to save some time by going faster (from a modest to begin with cruise speed). It's an effective fuel cost of $127.5 to save an hour to go 10 knots faster in zero wind or $46 to save an hour to go 10 knots faster in 50 knot headwind.

Moral of the story is, it's ok to get impatient and go faster when facing stiff headwinds, you won't be paying as much to go faster as in still air.

[A64Pilot]

On 10/31/2022 at 8:35 PM, Hank said:

Easy math, yaay!

135 knots ÷ 8 gph = 16.9 mpg

155 knots ÷ 10.5 gph = 14.8 mpg, or 14.8% faster and 12.4% more fuel.

Surprised no one has hit on the illogic of those numbers.

The 10.5 at 155 I get from the internet, and assume it’s likely between 7 and 10 thousand ft.

The 8 at 135 is what I actually burn, but at low altitudes, typically 1,000 MSL.

Assumption is higher will give higher speed for 8GPH?

So it’s not actually a good comparison

[A64Pilot]

22 hours ago, 201er said:

Demonstrated a bunch of pretty real world numbers in this example:

At today's gas prices, makes an even bigger difference. For example 1000nm trip with $8/gallon fuel:

145ktas@8.5gph vs 155ktas@10.0gph

0 wind: $469 in 6.9 hours or $520 in 6.5 hours, $51 to save 0.4 hours

50 knot headwind: $714 in 10.5 hours or $760 in 9.5 hours, $46 to save 1.0 hours

The stronger the headwind, the lower the premium to save some time by going faster (from a modest to begin with cruise speed). It's an effective fuel cost of $127.5 to save an hour to go 10 knots faster in zero wind or $46 to save an hour to go 10 knots faster in 50 knot headwind.

Moral of the story is, it's ok to get impatient and go faster when facing stiff headwinds, you won't be paying as much to go faster as in still air.

What that really points out to me is by not waiting until the headwind isn’t there, cost you like $245 

[201er]

10 minutes ago, A64Pilot said:

What that really points out to me is by not waiting until the headwind isn’t there, cost you like $245 

Not usually a real choice. You usually choose between headwinds or the really nasty front, thunderstorms, and hard IFR that comes before/after. Most of the flights I did in absurd headwinds was a choice because the +/- day alternative was worse. You could be waiting a while.

[A64Pilot]

On 11/2/2022 at 9:17 AM, 201er said:

Not usually a real choice. You usually choose between headwinds or the really nasty front, thunderstorms, and hard IFR that comes before/after. Most of the flights I did in absurd headwinds was a choice because the +/- day alternative was worse. You could be waiting a while.

Hence, time to spare, go by air. When crossing the Country especially headed West my technique was to fly as close to the nasty front as possible and land, let the level 5 thunderstorms pass over in the night then get up next morning and go, didn’t hit too many nasty winds usually.

But nothing works every time, then I had to go, work schedule, now that pressure is off most of the time. When I have to be somewhere now if Wx is possible, I just leave a few days early, be a tourist for a couple of days. I don’t push Wx like I used to anymore.

[Hank]

2 hours ago, A64Pilot said:

When I have to be somewhere now if Wx is possible, I just leave a few days early, be a tourist for a couple of days. I don’t push Wx like I used to anymore.

That day is coming for everyone, but many of us still have a ways to go so we need a plan besides "wait a few days for it to move away." Personally, I waited an extra day for enroute icing, then flew around it the next day in high winds. Because the other choice was a ten-hour drive, then a return at some point to get the plane while daily parking fees added up.

[A64Pilot]

Back when I was a kid we travelled in my Father’s 182.

This was the 1960’s and every now and again we would all fly home Commercial, and a week of two later he would fly out and retrieve the airplane.

Later my Brother and I were doing the NAAA State meetings circuit https://www.agaviation.org in the 210 and got iced in in Tx. we rented a car and did a lot of driving before we could get back to the airplane.

Only point is if traveling by GA, especially in Winter, have a plan B if you have to be somewhere, cause I promise it will become necessary. My plan B now is to just wait it out, it didn’t used to be of course and every now and again I flew in Wx I shouldn’t have, especially when delivering aircraft in Central and South America

[Shadrach]

On 10/25/2022 at 6:05 PM, A64Pilot said:

your right, save fuel thereby increasing range. I misspoke.

I’m not saying your wrong so much as I’m saying often that “best advice” given on the internet often is, like for instance to keep from losing any speed LOP, simply increase MP until your speed is recovered. Sounds good but often isn’t possible.

I’m flying WOT now, how do I increase MP?

Maybe it’s just me and the people I hang around, but when traveling, the throttle is opened on takeoff, and not touched until the let down at destination. Altitude reduces the throttle for me.

 

I think most of us fly that way.
I certainly do…in spite of my POH’s suggestion to reduce throttle to 26X2600 in climb and to repeatedly adjust it and the ram air to maintain 26X2600 all the way up to cruise altitude. It’s like whoever wrote it was asking “how can I make something quick and easy more complicated and task oriented?”.

[N201MKTurbo]

OK, going back to the original title....

I was doing a flight review yesterday and on the third T&G (I'm still alive!) The tower controller said "Cleared for touch and go number two behind the Cirrus, seriously"

[jaylw314]

On 11/1/2022 at 7:28 AM, 201er said:

At today's gas prices, makes an even bigger difference. For example 1000nm trip with $8/gallon fuel:

145ktas@8.5gph vs 155ktas@10.0gph

0 wind: $469 in 6.9 hours or $520 in 6.5 hours, $51 to save 0.4 hours

50 knot headwind: $714 in 10.5 hours or $760 in 9.5 hours, $46 to save 1.0 hours

The stronger the headwind, the lower the premium to save some time by going faster (from a modest to begin with cruise speed). It's an effective fuel cost of $127.5 to save an hour to go 10 knots faster in zero wind or $46 to save an hour to go 10 knots faster in 50 knot headwind.

Moral of the story is, it's ok to get impatient and go faster when facing stiff headwinds, you won't be paying as much to go faster as in still air.

While the cost calculations are relevant, the part that cost misses is the margin from reserve fuel left on landing.  I'm not sure you can apply cost to that--how many accidents from fuel starvation are there where 'unexpected headwinds' are part of the chain?

[carusoam]

On 11/7/2022 at 1:04 PM, jaylw314 said:

While the cost calculations are relevant, the part that cost misses is the margin from reserve fuel left on landing.  I'm not sure you can apply cost to that--how many accidents from fuel starvation are there where 'unexpected headwinds' are part of the chain?

We know of two…

Essentially, two MSers needed to fly to another airport to get fuel…

A bit of a miscalculation…. Followed by off airport landings…

Fortunately… my memory isn’t strong enough to remember all of the goof ups… 

Best regards,

-a-