Fuel Burn Rates

[LJ Driver]

Originally posted by HerkDriver24:

You could have fooled me.

HD

Good one.

[Guest Hoser]

LJ / HD24,

Are you ladies done b!tch slap fighing with each other?

If so, how about adding something useful to the thread.

If not, you can continue your fight, via PM, until you fingers can't type anymore.

Both of you, drink a and chill.

Hoser

[Scooter14]

Hey Hoser,

Who died and made you a moderator?

Oh, yeah. The KC-135R burns approx 15,000 the first hour and 10,000 after that. Loitering we can get down to about 7500-8000 while waiting for our last set of receivers if we are really light.

[Guest THE10MAN]

"Loitering we can get down to about 7500-8000 while waiting for our last set of receivers if we are really light."

Or waiting for a KC-10 to consolidate into.

Sorry, couldn't resist.

[slacker]

Very nice. I'm talking about 1010 (or 932 for you) versus sitting back at 850

Wow, bragging about how fast you go in the herk? Come on, that's crazy fast.

Copilot- "Wake up, put down the box lunches and hang on...I'm pushing it up to 1010!"

The rest of the crew- "whatever."

Don't brag about how crazy fast the herk goes in front of crews from other airframes (except T-37 FAIPS), that's just embarrasing. Even when I've seen 355 ktas, I wouldn't brag, except in front of other herk guys. Remember, slow is cool, especially on the way back to the deid from east (not really, slow sucks, especially when you miss the beer.)

[HerkDerka]

Okay. Go back through the WHOLE thread.

Did I once mention the words "Herk" and "Fast" in the same sentence?

No.

Hell, I didn't even mention TAS!

And it was never a brag. I'm talking about guys who purposely bring the engines back with the intention of "saving gas". It's a cop out in the Herk and the difference in fuel and TOA each way is negligible.

HD

[ 10. November 2005, 04:39: Message edited by: HerkDriver24 ]

[Guest purplecaddis]

Originally posted by HerkDriver24:

Okay. Go back through the WHOLE thread.

Did I once mention the words "Herk" and "Fast" in the same sentence?

No.

Hell, I didn't even mention TAS!

And it was never a brag. I'm talking about guys who purposely bring the engines back with the intention of "saving gas". It's a cop out in the Herk and the difference in fuel and TOA each way is negligible.

HD

HD

I encourage you to do the math on lower TIT saving gas. It does not do it, in fact you burn more gas. Especially when you take in to account that your cruise ceiling is lower due to a lower cruise TIT.

Now the real reason for lower TIT is to save the turbines. Lockheed's data shows that turbine life is improved significantly from a reduction in TIT temps.

[HerkDerka]

That was my point bro. I said the difference either way is negligible and pulling them back to "save gas" is a cop out.

I understand the turbine blade school of thought, but I don't buy to an extent. The engine is going to shit itself well before the turbine life is exceeded.

HD

[HerkDerka]

Remember I said to an extent.

Now for discussion's sake. How many engines have you shit (non turbine related) as opposed to the one turbine failure?

HD

[ 10. November 2005, 06:24: Message edited by: HerkDriver24 ]

[Riddller]

I've shut down 15-20 engines in-flight in the Herk for almost every reason in the book, 2 of which were shifts in the turbine section that blew off the back quarter of the motor, but neither of them were due to the 'excess sulfidation' that Lockheed says 1010 will F-up the turbines. We mostly ran 980 TIT, but it wasn't uncommon to push it up to "Moral Speed" (I like that BTW!) every once in a while. I'll have to agree w/ HD on this one.

[HerkDerka]

Turbines are always a hot topic in the Herk community after the accident. People have a hundred different perspectives on it. "The books says we can do it" "It doesn't matter, it going to wear the blades down" "Then why does the dash one allow 1010/932?" "It's a suggestion for when you need it".

It comes down to how many hours are on the engine and how much abuse it has taken.

Every Herk driver has their view on it and usually quite a bit to back it up. It doesn't change the fact that the view on the subject changes from one person to the next.

HD

[Scooter14]

Originally posted by THE10MAN:

"Loitering we can get down to about 7500-8000 while waiting for our last set of receivers if we are really light."

Or waiting for a KC-10 to consolidate into.

Sorry, couldn't resist.

If we're that light, we are only instantaneous plus 10 to 20, so that's a good thing for you guys

For all you Herk guys, can you explain TIT, 1010, 932, 900 and all these other crazy prop related things that Mungo don't understand?

[Rocker]

Our TIT (Turbine Inlet Temp) = your ITT (basically). Assuming you have ITT in that plane... Same concept. And all this talk is about setting a certain cruise power based on TIT. Max continuous TIT is 932/1010*C depending on which engines you have and it does say that cruising at max cont. will reduce engine turbine life. 900 is recommended to extend turbine life.

[Riddller]

Also, TIT is what is used for power settings up at altitude. Down low, or for takeoff, 1010 TIT can give you torques WAY above what is allowed, but not up at altitude. So down low, you go by max torque for power settings (assuming you're not worried about those pesky airspeed restrictions) and up high by TIT.

[Guest SuperStallionIP]

I see there is in-fighting amongst the HERK-ed Ones. I want to see a walk-off leading into a break-dance fight and finishing up with seeing who can flash the best look.

[Guest ELan]

Thanks to those who responded...some good stuff.

Now that this has morphed to a Herk TIT discussion I thought I would chyme back in. My unit has upgraded to the H3 and thus the -15 engines. One of the planes that we received we flew for about 3 months before it was do for ISO. During the ISO they found that three of the engines had turbine problems and one of them actually was missing a turbine blade...and as it was explained...the turbine blades are designed to disintigrate when they seperate. The units response to this was that we will fly whatever TIT gives us 300 TAS not to exceed 1010 obviously.

So while the gas conservation doesn't factor in, turbine life does. I'm with Gearpig. I would imagine that there are plenty on AD that really don't give a sh!te and that is there parrogative....

[Guest TomandFle]

On a similar but unrelated note (so I don't have to start a new thread)...

Does anyone have a rough estimate of the engine(s) lag time for your jet? i.e. from straight and level trimmed flight, a throttle increase to max power would lead the engine response by about (x) seconds. Just a rough estimate is fine... trying to model this in Simulink as part of an autopilot design.

[Guest Hoser]

Originally posted by Scooter14:

Hey Hoser,

Who died and made you a moderator?

Suck it, Trebek.

Originally posted by Scooter14:

For all you Herk guys, can you explain TIT...

You said TIT!

Originally posted by BigIron:

I want to see a walk-off leading into a break-dance fight and finishing up with seeing who can flash the best look.

I can Darel lick my own balls, thank you very much.

I normally have only 2 power settings: IDLE or MAX.

Hoser

[Guest purplecaddis]

Originally posted by gearpig:

HD, I can personally tell you that the turbine blades will shit themselves before the engine. As a new copilot, my AC decides to fly 932 from Indian Springs, NV to Ft. Campbell because there was a minor emergency at home. Nothing says we can't, it's just not recommended. Just outside KHOP, the number 3 engine turbine shells. Long story short, MX replaces the engine and while doing an engine run on 3 with symmetrical power on 2 - Boom, we're picking up #2 turbine blades all over the ramp. Engine #1 and #4 also had turbine damage. Why, only because he used 932 for four hours instead of 900.

Gearpig,

It was not that four hours at 932 that caused the turbine failure. Two things to keep in mind about the turbines/engines. First they were designed to be run at 932, thats why it is called NORMAL cruise. Second they are designed to fly to failure. Yes there are scheduled rebuilds and inspections, but ultimately you fly that engine to failure.

A few years back we had a crew crap a turbine. It was a catastrophic failure that was not contained, i.e. pieces flew out of the engine. Not a good situation at all, but they brought the airplane home and everybody was fine. This all happened while flying the airplane at 900.

The point to the story is most likely you would have crapped the turbine on that sortie either way.

I can not prove it but I feel like we are having more of these catostrophic type failures because we are flying this engines longer than intended. The -7s are getting old and there are no new -7s being built. Instead we are trying to keep the engines we have flying longer. But that and two level depot mx are conversations for a different day.

[Guest Xtndr50boom]

Originally posted by Hoser:

I normally have only 2 power settings: IDLE or MAX.

Spoken like a wingman.

I'm confused. Is it some sort of epipheny (sp?) that having a higher TIT or whatever will lead to reduced engine life? This crap was figured out years ago; that's why god invented "de-rate".

[Guest Hoser]

Originally posted by Xtndr50boom:

Spoken like a wingman.

[LJ Driver]

Fighters have ejection seats too, so when your engine throws a blade you can punch. Heavy boys need to be slightly more cognizant of turbine wear.

[BFM this]

Originally posted by LJ Driver:

Fighters have ejection seats too, so when your engine throws a blade you can punch. Heavy boys need to be slightly more cognizant of turbine wear.

OK, I'll bite, why am I willing to bet a ride up the rails on my ignorance of turbine wear? Why are "Heavy boys" more concerned about this when they will typically loose 25-33% of thier engines when one throws a blade whereas fighters will loose btw 50-100% of thiers. I won't go into the percentage of time I spend "enroute" vs down in the weeds savagely beating my throttle stops to death.

Do tell.

Having crossed a pond or two in the Herc, I'll wager that the reason "Heavy boys" are more cognizant of things like turbine life vs TIT is because around the 6th hour the conversation gets driven to that level from boredom and the incessant "can't we push it up?". Not because anyones got anything more riding on the question.

Xtndrboom, you're on to something there: at least locally we climb and cruise at reduced ITT settings for turbine wear. But we also have override switches just in case (theres the derating)-->would prob torch the remaining motor, but it will get us back home if we lost the first one in a critical (high/hot/heavy) situation.

[Riddller]

Originally posted by BFM this:

Having crossed a pond or two in the Herc, I'll wager that the reason "Heavy boys" are more cognizant of things like turbine life vs TIT is because around the 6th hour the conversation gets driven to that level from boredom and the incessant "can't we push it up?". Not because anyones got anything more riding on the question.

Got a point there...

In my experience, I'd say you'd win that bet BFM.

[Guest Xtndr50boom]

This Q is more for BFM and Hoser:

Are fighter engines flown to destruction, or are they replaced at a certain hour timeframe? Me thinks a viper/single engine would go by time but you never know until you know, you know?

In the 10, if I understood what was going on, we'd set the thrust computer to TO FLX, along with current temps and use the N1% it displayed for engine life. Obviously N/A if we needed more go-go power, but according to GE it helps out.