Throttle control

[dtango]

Where does chopping throttle make sense from an angles perspective?  Here's one specific instance I posted in another thread worth repeating....


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Impact of Airspeed on Nose-to-Nose Turns

Separation distances between aircraft impacts nose-to-nose engagements in other ways as well.  Turn radius is actually not the only factor that determines advantage in one-circle engagements. 

In certain nose-to-nose situations turn radius doesn’t determine angular and positional advantage.  Instead it’s determined by airspeed instead.  How much advantage depends on the separation distances between airplanes.  Consider the following diagram:





In the illustration we have red and blue abeam of each other with circular flight path overlays to visualize the turn circles.  Red has a smaller turn radius but greater airspeed while Blue has a larger turn radius but is travelling slower than Red.  Blue is able to get the angles advantage because it is travelling slower than Red despite it’s larger turn radius and lower turn rate!

In a nose-to-nose turn when aircraft are abeam of each other and the separation distance between the two is less than the turn radius of the larger turn circle the aircraft with the slower airspeed gains the advantage.

This is one of the ways planes like the P-51 will catch better turners by surprise.  For instance when I’m flying a P-51 against a Spitfire XVI and I recognize that we’re in this situation I’ll yank throttle to idle and deploy as much flaps as I can in an effort to slow down and force the Spitfire out front.  This is a situation where chopping throttle makes sense.  Just keep in mind that it may leave you no margin for error if you can't get in position to make that shot count with your throttle chopped.

If the separation is greater than the larger of the two turn radii then turn radius becomes the dominant factor once again.

Tango, XO
412th FS Braunco Mustangs

[Murdr]

Thanks dtango, you've saved me quite a bit of typing time.

[dtango]

Thanks dtango, you've saved me quite a bit of typing time.

Hehe murdr.  I'd say you owe me !!! .... except for the fact that I was pretty much cutting and pasting from past posts anyway! 

Tango, XO
412th FS Braunco Mustangs

[Oldman731]

Why some folks think chopping throttle below corner improves your maneuverability is beyond me.  I don't know where people get the idea that the slower you go the better turning you are.  I think it comes from using the inaccurate car/bike analogy.  That's a bad analogy to use. 

For some of us it comes from experience.

Your chart shows why.  There's no question that your instantaneous turn radius and rate are best at corner velocity; you've convinced me.  But corner velocity only exists in a fight for a brief moment, unless you're literally staring at your airspeed indicator throughout the it's-gonna-be-quick-now fight.  People slow down because it gets them closer to the best sustained turn rate, which is what usually counts when you're pursuing someone, and even after you've made your original break turn.

- oldman

[dtango]

For some of us it comes from experience.

Your chart shows why.  There's no question that your instantaneous turn radius and rate are best at corner velocity; you've convinced me.  But corner velocity only exists in a fight for a brief moment, unless you're literally staring at your airspeed indicator throughout the it's-gonna-be-quick-now fight.  People slow down because it gets them closer to the best sustained turn rate, which is what usually counts when you're pursuing someone, and even after you've made your original break turn.

- oldman

OK let's talk about this idea of slowing down to best sustained turn.  Why would you not turn from corner and bleed down to best sustained turn with throttle on?  Your radius would probably be smaller and turn rate greater compared to simply chopping throttle while doing this.  With throttle on you would have more specific-excess-power available to counter increased drag due to lift which means you can turn tighter and at the same or smaller radius compared to with throttle off.

There are times when chopping throttle makes sense (e.g. trying to induce overshoots etc).  Saying that chopping throttle makes you more maneuverable as a general maxim is very misleading because it doesn't apply in many cases.

Tango, XO
412th FS Braunco Mustangs

[A8TOOL]

Slowing down in a turn that you already know you are going to fast to make tighter to take the shot is the way to go. Most high speed turns can only be made tighter by either reducing engine power or increasing engine tork,  I don't think anyone can convince me otherwise.

I realize some planes turn better to left and others to the right. Some planes turn better slow and others just need more speed to stay aloft and competitive. Retaining information like that has helped me determine when to throttle down and when to wep up. It's especially useful when considering engine tork and always depends on the choice of plane.

 It's an ongoing process of trial and error for me and it does not always work out like I want it. The charts say one thing but applying them effectively in the heat of battle is harder to do than just using my best judgment. Since I've never fully divided my attention between the gauges and the fight I probably won't ever become the greatest sim fighter pilot ever.... but I have gained some experience and do have a lot of fun

[A8TOOL]

It's not about chopping throttle, It's about throttle management, flaps and rudder. When to use them and why.

With the exception of planes like the pony and the f4u's, there are many planes that won't deploy flaps at higher speeds . In these planes throttle management is key. Learning which ones to do what in is challenging when you don't dedicate yourself to one type or another but all of them.

[Oldman731]

OK let's talk about this idea of slowing down to best sustained turn.  Why would you not turn from corner and bleed down to best sustained turn with throttle on?  Your radius would probably be smaller and turn rate greater compared to simply chopping throttle while doing this.  With throttle on you would have more specific-excess-power available to counter increased drag due to lift which means you can turn tighter and at the same or smaller radius compared to with throttle off.

There are times when chopping throttle makes sense (e.g. trying to induce overshoots etc).  Saying that chopping throttle makes you more maneuverable as a general maxim is very misleading because it doesn't apply in many cases.

Because of two things.  First, you aren't necessarily "chopping" the throttle, as A8Tool points out.  You would chop it if you were in danger of overshooting or were going way too fast, but generally I'm talking about reducing the throttle by something less than 100%.

Second, it's really the difference between theoretical and practical.  Theoretically it might be best to slow down exactly along the chart's curved line, but practically it's not possible to do this because you aren't sure what speed you began at and you aren't watching the airspeed indicator (unless you plan to lose sight of your target or of your pursuer).  I guess this was my original thought in starting this thread - many of the people I see aren't adjusting their throttle at all, probably because they know they can't watch their airspeed indicator and they're worried about getting too slow.  Slowing down enough to see that your turn is improving - regardless of whether you happen to be moving along the perfect-speed-line - is often a very useful technique.

- oldman

[BaldEagl]

There's no question that your instantaneous turn radius and rate are best at corner velocity; you've convinced me.  But corner velocity only exists in a fight for a brief moment, unless you're literally staring at your airspeed indicator throughout the it's-gonna-be-quick-now fight. 

Not true.  If you are used to a specific aircraft you can hold it at corner velocity for extended periods without ever looking at your airspeed indicator.  Beyond that, you have visual clues in a fight; am I gaining or losing ground and how quicky?  Minor adjustments of turn radius or throttle provide nearly instantaneous feedback as to the result; am I gaining/losing faster or slower than before or has the situation reversed itself?  Note that in these scenarios not once would you be looking at the instrument panal, yet you're maximizing your aircraft at it's best sustained turn rate.

[dtango]

Because of two things.  First, you aren't necessarily "chopping" the throttle, as A8Tool points out.  You would chop it if you were in danger of overshooting or were going way too fast, but generally I'm talking about reducing the throttle by something less than 100%.

Second, it's really the difference between theoretical and practical.  Theoretically it might be best to slow down exactly along the chart's curved line, but practically it's not possible to do this because you aren't sure what speed you began at and you aren't watching the airspeed indicator (unless you plan to lose sight of your target or of your pursuer).  I guess this was my original thought in starting this thread - many of the people I see aren't adjusting their throttle at all, probably because they know they can't watch their airspeed indicator and they're worried about getting too slow.  Slowing down enough to see that your turn is improving - regardless of whether you happen to be moving along the perfect-speed-line - is often a very useful technique.

- oldman

First, I'm absolutely in agreement with BaldEagl's response.  You don't need to be staring or constantly glancing at your airspeed indicator.  There are visual cues.  Personally before any kind of merge I note where my airspeed is at and make decisions and adjustments from that "initial" condition during a fight.

2nd - there is no "theoretical" here.  If you're turning better when you slow down assumming no incremental employment of high lift devices then either you a) started the turn above corner or b) were not in a max performance turn already before you got slower.

I'm in violent agreement that "two-handed-turns": one on stick, one on throttle is a skill to learn.  Learning the abilities of your aircraft, the envelope to fly it in, and the visual cues from the airspeed indicator to watching the movement of your opponent relative to you and modulating your throttle and stick as appropriate to maximize your performance is paramount.

My point is when you're in this mode, to improve turn performance sometimes you want to throttle it back, sometimes you want to throttle it up, sometimes you do both within a matter of a few seconds.  To say that throttling back ALWAYS improves your turn performance is a fallacy though. 

Tango, XO
412th FS Braunco Mustangs

[Oldman731]

If you're turning better when you slow down assumming no incremental employment of high lift devices then either you a) started the turn above corner or b) were not in a max performance turn already before you got slower.

My exact point.  It's fine if you're able to note your airspeed at the beginning of a fight, but quite often - most often, for me at least - you aren't.  More, you may not have flown the plane in awhile, and you perhaps don't know the corner speed or the sustained turn speed in any case. 

I'm in violent agreement that "two-handed-turns": one on stick, one on throttle is a skill to learn.  Learning the abilities of your aircraft, the envelope to fly it in, and the visual cues from the airspeed indicator to watching the movement of your opponent relative to you and modulating your throttle and stick as appropriate to maximize your performance is paramount.

My point is when you're in this mode, to improve turn performance sometimes you want to throttle it back, sometimes you want to throttle it up, sometimes you do both within a matter of a few seconds.  To say that throttling back ALWAYS improves your turn performance is a fallacy though. 

Then we agree.

- oldman

[Murdr]

My exact point.  It's fine if you're able to note your airspeed at the beginning of a fight, but quite often - most often, for me at least - you aren't.  More, you may not have flown the plane in awhile, and you perhaps don't know the corner speed or the sustained turn speed in any case. 

As long as you have a ballpark idea of your speed that's all one needs.
1.  Can I induce a full visual black out?  Yes=at or above Cv  No=see #2
2.  Can I induce a 1/2 visual black out?  Yes=between Cv and Sustained  No=see #3
3.  Can I deploy flaps?  Yes=see #4 No=near or below sustained but above flap speed.
4.  Can I induce near a full black out?  Yes=near max flap speed (flap Cv).  No=see #5
5.  Can I induce a 1/2 visual black out?  Yes=between Cv and Sustained

For throttle management considering ONLY max turn performance:  4 in a nose down attitude I would consider chopping the throttle.  1 I would consder chopping the throttle if it was in a nose down attitude, or if I felt "too far" above Cv.  3 I might consider slowing to flap speed by chopping the throttle if it's appropriate.  It's possible I'm forgetting a scenario, but that's pretty much it for reducing throttle to achieve the best turn performance.

The point is that other reasons for reducing power are not "to turn tighter"/max performance.  The reasons are about relative E states, or the geometry of the fight, or reducing the dominante torque force at or below stall.

Sustained turn is simply where your power output and the forces consuming that power are at equalibrium.  Reducing power at that part of the envelope only makes your turn performance worse.

[BaldEagl]

I could be wrong but it seems to me that the best sustained turn rate in most planes happens just as the stall horn starts to sound and just before you enter the stall buffet.

[SlapShot]

What is the advantage of closing throttle below corner speed?

There are many times when I will chop throttle (full chop) to assist in a tight ruddering move to snap the plane around much quicker ... for a snap shot or to gain an advantage behind one's 3-9 line on a merge.

I mainly fly the FM2 and F5F and throttle control is paramount in those planes when trying to tussle with Spit and Hurricanes. Many people cannot understand how these planes can get around so quickly either in a turn or rolling scissors.