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Minimum torque for lift off?

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There is no minimum... Torque will change with Alt and Temp so at a very high very hot airport the Tq will be low...

Speed is the number we use...

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If I remember correctly, the -1-1 listed an "expected" static torque based on temp, pressure altitude, etc., for a 95% engine. But I've never heard of an aborted takeoff for an engine with less than the expected. I'd glance at the torque but was concentrating more on RPM, TIT and FF.

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If you do not get Cal TQ you "should" abort the takeoff... Not a SHALL but...

If you do not get Cal TQ you "should" abort the takeoff... Not a SHALL but...

Whats up with the scroll box?

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If you do not get Cal TQ you "should" abort the takeoff... Not a SHALL but...

The vol3 says that if you can't make torque with the bleeds open then you should close them and recheck torque to determine if it's an engine problem or a bleed air system problem, but either way you will not fly the airplane.

As for minimum torque, 970 is the normal TIT for takeoff, and you have to make 95% efficiency, so the minimum torque for takeoff would be whatever the predicted torque is for 970 degrees at 95%.

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The vol3 says that if you can't make torque with the bleeds open then you should close them and recheck torque to determine if it's an engine problem or a bleed air system problem, but either way you will not fly the airplane.

As for minimum torque, 970 is the normal TIT for takeoff, and you have to make 95% efficiency, so the minimum torque for takeoff would be whatever the predicted torque is for 970 degrees at 95%.

970 can under certain circumstances result in torque that exceeds 19,600 so therefore this information is misleading.

Not sure what “Vol 3†is but Chapter 3 of our book NA-01-75GAI-1.1 pg 3-8, States “If torque computed for takeoff is not obtained, the takeoff should be aborted.â€

Closing the bleed air valve will result in a torque increase however you NEED to recalculate the calculated torque for “all bleed off†or your comparison (actual to calculated) will be invalid.

Yes you can determine the cause engine or bleed air system, but only if you recalculate the torque value. Bleeds off will result in about 650 inlb increase which is pretty uniform across the scale.

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The vol3 says that if you can't make torque with the bleeds open then you should close them and recheck torque to determine if it's an engine problem or a bleed air system problem, but either way you will not fly the airplane.

As for minimum torque, 970 is the normal TIT for takeoff, and you have to make 95% efficiency, so the minimum torque for takeoff would be whatever the predicted torque is for 970 degrees at 95%.

Depends on the Vol 3 you use! Ours states "TIT will not be less than 1010 for takeoff, not to exceed 19.6 of torque". We also compute 95%; however, we always hope for better.

Ron

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The "vol3" is the USAF book "Operations Procedures" and there's a slightly different version for each variant and command.

Absolutely you have to recalculate for bleeds closed, I didn't mean at all that you should just close the bleeds to make up for a lack of torque with them open. You also do have to reduce TIT for cold weather to avoid exceeding torque but minimum torque is still whatever you come out of the chart with. In the example for my particular variant the 970 "normal" number works for the vast majority of our operations but is not a blanket number.

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The "vol3" is the USAF book "Operations Procedures" and there's a slightly different version for each variant and command.

Absolutely you have to recalculate for bleeds closed, I didn't mean at all that you should just close the bleeds to make up for a lack of torque with them open. You also do have to reduce TIT for cold weather to avoid exceeding torque but minimum torque is still whatever you come out of the chart with. In the example for my particular variant the 970 "normal" number works for the vast majority of our operations but is not a blanket number.

I agree... didnt mean to poke you in the eye just some of our members may not be as versed as others...

Also remember if you use a reduced TIT you must make the TIT correction to all of your charts that have a TIT correction scale.

Takeoff Factor being very important...

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Hmmm...rolling down the runway on a touch-and-go...IAS 125...flaps 50%...torque zero...pull on the yoke and it will lift off....

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I remember when reduced power T/Os were started. Seems like it was 1975 or so when I was in the 32nd. Being a new Herc FE I wasn't sure how I felt about it. In recips, C-131, C-118, T-29, T/O power and go. So in the Herc, guess I just felt uneasy.

During a Commander's Call we had an IP, Capt. Roger Phelan, give a safety briefing. He said that during engine out operation after takeoff, and Vmca, to set the torque to correspond to the TOLD data. This sounded really wrong to me, but being the experienced 100 hr FE that I was, I kept quiet since no one else was speaking up.

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Hmmm...rolling down the runway on a touch-and-go...IAS 125...flaps 50%...torque zero...pull on the yoke and it will lift off....

This is just dumb!

125 will become 105 pretty quick then 95 then.... and then YOU will become "someone who killed the rest of the crewmembers on board!

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During a Commander's Call we had an IP, Capt. Roger Phelan, give a safety briefing. He said that during engine out operation after takeoff, and Vmca, to set the torque to correspond to the TOLD data. This sounded really wrong to me, but being the experienced 100 hr FE that I was, I kept quiet since no one else was speaking up.

It may sound "wrong" and ONLY after considering all other factors (terrain, climb capabilities, etc.) this is not "bad" advice.

The reason I say that is if you have the power necessary to climb (say straight ahead out over the water) a reduced torque value will result in your VMCA KIAS to go down.

So based on the statement made setting the reduced TIT torque “AFTER” VMCA is reached will help with directional control.

VMCA is based on Max power on the operational engines. This will be the MOST asymmetrical torque condition and VMCA is the lowest IAS that will allow for directional control under the conditions that define it.

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This is just dumb!

125 will become 105 pretty quick then 95 then.... and then YOU will become "someone who killed the rest of the crewmembers on board!

Well...ummm....ahhh...never mind...

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It may sound "wrong" and ONLY after considering all other factors (terrain, climb capabilities, etc.) this is not "bad" advice.

The reason I say that is if you have the power necessary to climb (say straight ahead out over the water) a reduced torque value will result in your VMCA KIAS to go down.

So based on the statement made setting the reduced TIT torque “AFTER” VMCA is reached will help with directional control.

VMCA is based on Max power on the operational engines. This will be the MOST asymmetrical torque condition and VMCA is the lowest IAS that will allow for directional control under the conditions that define it.

Think you're confusing the issue. Vmca, max power on operating engines, 5 degree bank away from dead engine, full rudder deflection/180 lbs of force (if memory serves). Your way, sure Vmca will go down, but may not give you a climb speed needed. Out over the water straight and level is one thing, flying around land locked states, with hills, mountains, trees, buildings is another. Reducing power will help with directional control, but is will also let the airplane bleed off energy. Energy is maneuverability.

We always taught the students that once everything gets settled after shutdown, pull back throttle on symmetrical engine to help with directional control but the 2 symmetrical operating engines are up, typically past where the reduced power torque would be. After being in the 16th for 4 years I saw many a student pilots in 3 engine situations - after liftoff, 3 engine go-arounds, etc. And had a fair share of actual 3 engine operations.

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You forgot #1 Windmilling on NTS, gear down, 50% flaps...

I did not want to confuse the issue but I think WE have....

So to recap:

There is no minimum Torque setting for takeoff...

Torque will change with Alt and Temp so at a very high (High Pressure Altitude), very hot (High OAT) airport the Torque will be low... (you need a longer runway or must reduce you aircraft takeoff weight)

Speed is the number we use... Takeoff speed ensures a margin above stall speed (1.1)

As Stated

It may sound "wrong" and ONLY after considering all other factors (terrain, climb capabilities, etc.) this is not "bad" advice.

…if you have the power necessary to climb (say straight ahead out over the water) a reduced torque value will result in your VMCA KIAS to go down.

Never was there a discussion about reducing power (flying around land locked states, with hills, mountains, trees, buildings)

“We always taught the students that once everything gets settled after shutdown, pull back throttle on symmetrical engine to help with directional controlâ€

This is exactly what we are talking about VMCA is ALL about directional control...

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