.speed

[hammer]

Auto-Speed as in Auto-Climb? (alt + x)
And you actually use the IAS? I've learned not to trust that dial. It's killed me more then once.

Alt-X is auto-speed, not auto-climb. In its default setting, it will put you in a climb. It can be set for any speed you wish, including speeds which will require a dive to reach. The speed you set is indicated airspeed. The plane will constantly adjust to the necessary angle of attack to maintain that IAS, which is a constant regardless of altitude.

Regards,

Hammer

[Mace2004]

Default Auto Speed does not take into account altitude or aircraft weight.  The default is the speed that gives you your best rate of climb (Vy) at sea level.  As you go higher Vy goes down so, if you really want to work for the best rate of climb, set lower speeds as you get higher (you have to experiment with this).  I played with this once for the 163 and cut almost a minute off of a climb to 30k, you just need to figure out if it's worth it to you.  Just as an OBTW, I've never seen it written regarding AH but I suspect that auto-takeoff should give you your sea level speed for best climb angle (Vx).  This is lower than Vy but should help you clear high terrain near the field.

It does happen that Vy is a good approximation of your best glide speed but it's only an approximation.  Also, as others have commented, your glide is greatly improved by either a stopped prop (i.e., not windmilling) or setting the lowest possible RPM.  Don't forget to get rid of extra ordnance/tanks.  The idea of using auto-speed climb until your engine quits may work but only in a limited number of circumstances.  There is a fairly complex method of determining the best max range profile to fly (this is done for modern bingo profiles) but in AH you'd only be guessing and are as likely to hurt your range as improve it.  For instance, if you climb, you're traveling less horizontal distance per unit of time so, while you may be improving your glide range by getting higher, you'll be farther from the field when your engine quits.

The best range profile depends on distance to go, weight, starting altitude, winds, etc., so for AH it's probably better to just keep it simple.  If you're low, climb to a few thousand feet above the airfield altitude, then level off and throttle back to best cruise engine settings.  Once you have the field in reach you can shut down the engine to save a bit of fuel in case you bugger up your first landing attempt.  In any case, once your engine stops stay level until you decelerate to your best climb speed (this can be as low as about 150 but goes as high as 300 for a 262) and then set auto-speed for the descent.

[Traveler]

I believe auto climb sets your plane to the maximum climb rate for the speed it is going. So on take off your climb rate will increase with speed and alt until you reach your maximum climb rate for "x" plane at "x" alt. The climb rate changes as alt changes. It makes your plane follow the climb and speed curves on the charts (right click plane in hanger>> speed or climb chart).

By the way....if you engage auto climb and get to max climb for your alt and speed then turn the engine off your glide descent angle will now be set to the most efficient descent for your speed and alt. As the plane descends it will keep your plane on the optimum glide slope for power off.

Question? - If you engange auto climb then reduce throttle back to almost idle ( or setting that wont allow climb) will the plane then bet set for optimum glide slope for that power setting? It would be much better to reduce throttle and fly optimum glide slope than with the engine totally off because you could cover even more ground distance with low power than no power and make it back faster. This would be great for low fuel situations.

I not sure that your statements about auto climb are correct.  The alt x keyboard command turns on the auto climb and from what I have experienced auto climb is dependent on airspeed.  The result is the aircraft pitches up and slows until the desired airspeed is reached.  I know in the P38L if I turn on the auto climb “alt x” and my airspeed is below the climb speed the aircraft trims the nose down to gain speed.  I am not sure if it trims for “Best Rate of Climb” or “Best Angle of Climb”.  I also don’t know that “alt x” yields the most efficient or “Best Glide Speed”. 

In answer to your Question, No,  Again it’s my experience that the Best Glide Speed is neither the Best Rate or Angle of climb speed.   Best Glide Speed is also calculated for Engine out and depending on the type of aircraft engine either feathered or set to zero pitch..

[kvuo75]

today i spent 2 hrs testing every plane's default alt-x climb and added the info to my super-duper fuel burn chart..

the actual usefulness, outside of the OP's original question, is dubious at best tho

anyone interested, fire me a pm with an email adresss. the chart is a 1 page .pdf..

if this dont work:

http://www.mediafire.com/?mvyjdedzzug

[Agent360]

I am going to throw out some statements to be corrected. What follows is SPECULATION. It is for discussion.

My original assumption that is incorrect according to Mace2004:
When auto climb is engaged the plane flys at maximum climb rate with the airspeed adjusting to accommodate the climb

rate. This results in the plane climbing according to the published climb rate chart for each plane.

Established fact:
Every plane has a "default" ".speed" setting. Further, we can change that setting to what ever we want.


Assumption 1:

When auto climb is engaged (alt+x) or auto take off is used the plane will fly to the .speed amount set. The plane

establishes the .speed velocity AND max climb for that speed at sea level. The velocity stays the same.

As the plane gains altitude the climb rate will remain at the max amount for .speed "X" at sea level. If the plane

CAN climb more at X altitude than at sea level the plane will continue to remain at the maximum climb rate for sea

level. So if the planes max climb at 150 mph at sea level is 2k/min but at 5k the planes max climb rate at 150mph is

3k/min the plane will only climb at 2k/min because that is what it can do at sea level.

Assumption 2:

default .speed = 150
auto take off at sea level

At 1,000 feet the plane maintains a velocity of 150 and climbs at the maximum rate for 1,000 feet. As the plane

continues to climb (2k..3k...) the climb rate will also change so that the plane is always flying at its maximum

climb rate for .speed 150 at any particular altitude.

Auto climb will fly a max climb rate for a set speed and automatically adjusts the climb rate to keep the .speed

velocity. As altitude changes so does climb rate but velocity always stays the same.
end scenario 2

Which assumption is correct?

Analysing the 109k4 speed and climb chart we have the following

At military power:

5k alt = max airspeed of 370 mph
5k alt = max climb of 3750 ft/min
One would immediately think that the k4 can climb 3750 ft/min at an airspeed of 370 mph.
BUT...The airspeed chart is for level flight not climbing.

On the graph where the climb rate and airspeed intersect which is at about 15k the plane should climb at
3750 ft/min at an airspeed of 400 mph????

Now let us further complicate things.

If we set "auto angle" for climb (shift+x) what happens?

I am assuming that the plane will fly the set climb angle up. Using climb rate as that set angle we can further

assume the following.
A plane flying level at 150 mph. The plane is brought to a climb rate of 2k/min and auto angle is engaged. The plane

will now maintain a 2k climb rate until it reaches an altitude or air speed at which the plane can no longer climb

at that rate. At this point the plane will simply nose down and continue to climb at the maximum amount it can at

that alt?

In simpler terms. The plane is forced to fly at a the set climb (or Angle of attack UP in this case) regardless of

airspeed until the plane can no longer sustain the set AOT.

So we have the following:
Auto climb - sets a constant airspeed (.speed X) with a set climb rate for that plane (sea level). Speed remains

constant and climb rate remains constant for what the max climb rate is at sea level for that particular plane?
OR
Climb rate is adjusted to keep the .speed setting which means it is possible to have a climb rate higher than what

it is at sea level as long as the climb rate does not interfear with the velocity. If climb rate will cause the

plane to slow below .speed then the climb rate is adjusted to keep .speed constant?

Auto angle - sets a constant angle of attack (climb rate or descent rate) and adjusts airspeed to maintain that set AOT?
OR
only AOT is constant and airspeed is what ever your plane can do at X power setting. If climbing, air speed will

hold until you can't climb at the set AOT (as alt increases climb rate changes). If descending your plane will

remain at the set AOT but will continue to gain airspeed in the descent. Either way auto angle does nothing to set

airspeed only the AOT. Airspeed is controlled by your set climb or descent angle and the particular alt as you

ascent or descend?

So we don't actually have an "auto pilot" mode that will make the plane fly at maximum climb rate. We can not auto

set the plane to climb according to the chart?

[mtnman]

From what I see, we don't have an "auto-climb" setting.  We have auto-level, auto-angle, and auto-speed. 

The auto-speed is set at a default (around 150) which every plane in the game is capable of exceeding at full throttle.  Since the planes would exceed this speed, the nose pitches up at varying amounts to reduce/maintain the speed at the default setting.  Since the nose pitches up, most people consider this to be "auto-climb".  As we climb, the speed stays the same, since that's what auto-speed is supposed to do...  It doesn't "care" about climb angle, rate of climb or descent, or what's on TV.  It cares about the speed...



Since the default auto-speed is so similar across the board, I highly doubt it's based on "best" of anything, let alone "best climb" or "best glide when my engine gets shot out".  It doesn't seem reasonable to me that all the planes in the game conveniently climb at their best rate, all at about the same speed.  It may be convenient, but I doubt it's always the best...

In personal use, I believe I see evidence that the default isn't the "best" climb speed.  When my squadie lifts in the same plane as me, but earlier than me, I'll see him out say 4K in front of me, on auto-speed.  If I go on auto speed, I'll climb behind him, but never catch up, and never climb faster than him.  But...

If I reduce my climb angle, but still climb at full throttle, I'll fly at a higher speed.  Normally I do that by engaging auto-angle, or by typing in a .speed command, generally of 200-225.  When I do that, I catch up to my squadie, but also catch up to him in height.  That basically means I'm climbing faster than him, because I've matched his position and altitude, and I've been in the air for less time...  Neither of us will use WEP on a climb-out.

Another piece of evidence-  If I take off in my F4U at the same time as a spit8, and we both hit auto-speed, the spit will outclimb me.  However, if he's on my six, equal speed, chasing me, and I slowly bring my nose up to maintain 300mph (or us the .speed command) I'll pull away, and climb higher, faster, than him.  A spit at 150 mph climbs faster than an F4U at 150.  An F4U at 300 climbs faster than a spit at 300.

Best glide speed?  As an RC glider pilot, I've learned that nosing down, and increasing my forward speed can greatly increase the distance I can cover from a given altitude.  As a matter of fact, holding the nose up in an attempt to minimize loss of altitude will actually increase my angle of descent.  I may not fall any faster, but I'll cover less ground moving forward.  Need to stretch a bit to reach the field?  Push the nose down for speed, don't hold it up...

[Mace2004]

OK, interesting interpretation but your explanations are a bit tortured.  Let's forget Vx, it's mostly irrelevant and just confuses the issue, I shouldn't have brought it up.  Auto takeoff gives you a speed slower than Vy and I'm just assuming the HT set it at Vx but the discussion was really about the Auto-speed command.

An airplane can climb only when it can produce more power than is required for level flight.  (Remember, we're talking about sustained climb here, not zoom.) Any power over that required for level flight is called excess power.  The best ROC (altitude gained per unit of time) is achieved at the airspeed at which the airplane produces the greatest excess power for that altitude and weight.  For each combination of altitude and weight there will be an airspeed that will give you the best ROC.  That speed is called Vy and Vy generally decreases with an increase in altitude. 

So, let's just ignore weight and say your Vy at sea level is 150mph and, at full power, that will give you a ROC of 2000fpm.  Still using Auto-speed you climb to 10,000ft.  You'll still be at 150 mph but that will no longer give you the best ROC for that altitude.  In our example your ROC is now 1000fpm but if you adjust your auto-speed down to the correct Vy (say 140mph) maybe you'd be able to climb at 1200fpm. 

Auto-speed doesn't know or care what altitude or climb rate you're at, it just knows what it's programed airspeed is and will adjust the pitch attitude of your plane to fly that speed.  If you have more power than required for level flight at 150mph then you'll climb.  If you have less (like you're out of fuel) then you'll descend but the AP will trim to keep you at 150mph.

Your chart doesn't work because there is no correlation between sustained climb rate and maximum speed.  As you mentioned, it's important that you understand that the maximum speeds shown are for level flight.  All of that speed does equate to extra E that can be converted into altitude in a zoom climb but this isn't sustained so matching maximum speeds with sustained climb rate data doesn't work.

[Mace2004]

Howdy Mtnman

Best glide for range is at L/D max unless you have a headwind where you'll get better range by flying a bit faster than L/D max.  Conversely, with a tailwind you should fly slower.  Also, you should not dump your nose for extra speed, you'll just hit the ground sooner and shorter.  There's also the complication and confusion between best glide and minimum sink rate.  If you fly about 80 percent of L/D max you can get minimum sink rate but you get less range but you'll hit later.

Whether or not HT has accurately modeled the default values for Vy is arguable.  I've seen it reported that this was the intent but have never tested it.  Even so, it's not surprising most airplanes in AH have similar speeds as most are straight wing prop planes with the biggest variation being engine power which should increase Vy but then along with increased engine power comes inevitable increased weight which decreases Vy so it's likely the excess power equation is being somewhat balanced out.  That said, there is still a significant difference in default auto-speeds, for instance the 262 is 300.  Granted, this is an extreme example but all the airspeeds aren't 150.

[moot]

Agent, the planes do fly at the posted climb rates, as per the charts.  Like Mace said the auto pilot just holds the plane at whatever level angle required to reach the speed specified with .speed.  The climb rate is a function of that speed and the throttle settings.  Climb rate will vary at a fixed .speed and throttle only because the air gets thinner, and the plane thus has to fly at a shallower angle to maintain the specified .speed. 

[mtnman]

Howdy Mtnman

Best glide for range is at L/D max unless you have a headwind where you'll get better range by flying a bit faster than L/D max.  Conversely, with a tailwind you should fly slower.  Also, you should not dump your nose for extra speed, you'll just hit the ground sooner and shorter.  There's also the complication and confusion between best glide and minimum sink rate.  If you fly about 80 percent of L/D max you can get minimum sink rate but you get less range but you'll hit later.

Whether or not HT has accurately modeled the default values for Vy is arguable.  I've seen it reported that this was the intent but have never tested it.  Even so, it's not surprising most airplanes in AH have similar speeds as most are straight wing prop planes with the biggest variation being engine power which should increase Vy but then along with increased engine power comes inevitable increased weight which decreases Vy so it's likely the excess power equation is being somewhat balanced out.  That said, there is still a significant difference in default auto-speeds, for instance the 262 is 300.  Granted, this is an extreme example but all the airspeeds aren't 150.

Thanks for the explanation Mace!

I think what I see with my gliders, or my planes with the engine off, is that by holding the nose up (or at least not lowering it) is that I'm flying slower than L/D max?  By allowing my nose to drop/speed to build, I'm flying closer to L/D max?  I'm not talking about diving, just relaxing on the stick a bit...  I've done it enough to see that it makes an appreciable difference in how much ground I can cover, which is important when I'm trying to stretch my glide back to the field.

Playing with the auto-speed tonight, I seemed to get my best climb in the F4U between 160 and 170.  Dropping it to 140 hurt me for sure, as did increasing it to 180.  It was hard to tell for sure which speed was the best, because my RoC was dropping as I was climbing.  I was also reading a book while climbing, so I amy have missed something, hehe.

[Mace2004]

Thanks for the explanation Mace!

I think what I see with my gliders, or my planes with the engine off, is that by holding the nose up (or at least not lowering it) is that I'm flying slower than L/D max?  By allowing my nose to drop/speed to build, I'm flying closer to L/D max?  I'm not talking about diving, just relaxing on the stick a bit...  I've done it enough to see that it makes an appreciable difference in how much ground I can cover, which is important when I'm trying to stretch my glide back to the field.

I don't know much about RC gliders but would guess that's the case and it's one of the areas where all pilots tend to make mistakes because they follow their guts vice the rules of aerodynamics.  They have an engine failure and their first reaction is to maintain altitiude which they can do for a short time but this lets their speed decay and sometimes they'll even enter a stall.  The proper procedure is relax back stick pressure as they decelerate to their best glide speed and then lower their nose and trim to maintain that speed.  At that point you would have to lower the nose significantly to accelerate back to glide speed then pull the nose back up to maintain it. 

No matter what people think will happen, either lowering their nose further or raising it higher than that required for best glide will shorten their glide range.  Most engine-out landings, even off field, are survivable as long as the pilot stays in control but many will try to "stretch" the glide resulting in a stall and hard landing.  With your glider I assume that your reference is aircraft attitutude because that's all you can see, not the actual airspeed or AOA. This situation is very much "seat of the pants" flying with no instrumentation to guide you.  Glider pilots would have the same "intuitive" propensity to keep the nose up to maintain best glide and then end up just like the guy with a failed engine.  You slow to less than L/Dmax then have to get the nose down to accelerate. 

Knowing the aerodynamics is the key vice intuition.  For instance, say you're straight nose down at low altitude at 150mph.  What's the correct recovery procedure?  Most would cut their throttle and pull but in actuality, since you're well below corner speed (minimum turn radius) it's best to go full power to sustain your ability to turn with minimum radius.  That is most definently counter-intuitive.

Playing with the auto-speed tonight, I seemed to get my best climb in the F4U between 160 and 170.  Dropping it to 140 hurt me for sure, as did increasing it to 180.  It was hard to tell for sure which speed was the best, because my RoC was dropping as I was climbing.  I was also reading a book while climbing, so I amy have missed something, hehe.

Try playing with the 163 offline.  Select 0 fuel burn so your weight stays constant and fly an auro-speed climb to 30k.  Then do it again but use your .speed command to knoock off a few nots every 5k feet and you'll find you can get to 30k faster.  I'll have to look for my numbers but I found a profile that shaved almost a minute off the climbwhich is pretty meaningful given the 163 only has about 5 minutes of fuel.

[mtnman]

You've nailed it Mace, that's what I'm talking about.  The guys that strive to hold the altitude at the cost of airspeed...  In game, if auto-speed is close to L/Dmax, than using it as an "auto-glide" may be the best/easiest way to defeat that problem. 

And with the RC gliders or power planes that have lost power, it can be tough to figure out the best trim to get back to the field.  Not only are we limited by only seeing attitude, we often can't see that very well either.  An example would be if the plane is gliding toward the field, but also toward the pilot.  All you really see is the front profile view, it's hard to judge actual attitude, and very tough to get a visual idea of speed (even more than normal).  The visual idea of speed isn't all that acurrate anyway, since it doesn't take wind into account.

My normal/most accurate method to measure speed is control-response (with RC).  Too much response or too little response correlates to too much or too little speed.

In your 163 example, I agree, I've seen the same effect with being able to climb faster w/o using the default speed.  I also don't remember what speed I used, but it was slower than 300.  That also makes me wonder if the default climb correlates to L/Dmax in the 163.  I generally glide at a slower speed than that, but I may not be gliding at optimal speed.

How can we discover L/D max for a particular plane?  In game, just adjusting .speed to find the best climb speed should work, right?  And then again with the engine off, prop rpm reduced, to find best glide?  I guess I'd expect a different L/Dmax for the F4U-1D vs the F4U-4, but a similar optimal glide speed for both...

[Agent360]

Ok so we have established what "autopilot speed" or commonly refered to as "auto climb" (alt+x) does. Assuming full throttle no wep the plane climbs due to the execess of "power" from that required for sustained flight (ie just above stall). What ever that amount of execess is gives us a climb rate. The climb rate changes as alt changes for the .speed setting.

Further it has been stated that the max climb rate is not the fastest possible speed for a givin angle of attack. In other words flying slower will make your climb rate higher. I mean slower in terms or proportion...150 vs 180.

The big question:
What is the speed curve to fly the max climb curve according to the charts? For every 1k of alt there should be a corresponding speed that will make the plane fly at that climb rate. If you go too slow or too fast over this speed curve you will not be at max climb.

Obviously this speed curve would be effected by take off weight (fuel load, bombs etc). Lets just assume a plane weight quoted on the climb charts.

A few things to consider.
There is the "max climb" and there is "steepest climb". The speed that produces the best climb for both of these is different. Steepest climb would be used to clear a mountain. Max climb would be used to get to a target alt in the shortest amount of time.

Speed is related to throttle (power) and rpm (prop pitch). I am wondering if max cruise settings would produce the best possible climb rate. Perhaps one could achieve even higher climb rates at least for a short time my reducing throttle and rpm (steepest climb).

If one thinks about this it has great use in dog fighting (close in knife fighting at least). If one could use proper power to go from steepest climb to max climb and then to best glide then it would be possible maximise the verticle turns...getting into them and out of them...managing energy...etc. If this is done one can manipulate the angles to great advantage and perhaps keep much more energy over all.

If I know the steepest climb speed (or power setting) under 5k then I might want to maneuver to that speed and then climb at that speed. I then might want to roll over for a shot. After the shot I might want to immiedatly max climb...so I would maneuver to that speed and power setting and climb. Of course there are other factors...g load, flaps etc...but knowing these speed setting will shurely give an advantage.

Is there a dot command for "auto angle"? like..... ".angle 45".

I know I may be "torturing" this concept a bit. But since autopilot speed has nothing to do with the max climb of the airplane I now want to  explore this concept in more detail.

[kvuo75]

since our engines dont overheat, and never break down, there is no reason not to climb on full power other than fuel concerns..

theres no way reducing power is gonna give you a better climb rate.

[Mace2004]

How can we discover L/D max for a particular plane?  In game, just adjusting .speed to find the best climb speed should work, right?  And then again with the engine off, prop rpm reduced, to find best glide?  I guess I'd expect a different L/Dmax for the F4U-1D vs the F4U-4, but a similar optimal glide speed for both...

Sorry, but I know this gets confusing.  Best glide is at L/Dmax, which is minimum drag. For a prop plane, L/Dmax also ends up being the speed for maximum range.  This is not the same as Vy which is the speed for best climb rate.  For the purposes of AH using best climb rate for glide is only a rough approximation but has the advantage of being easy to do.  If your life could depend on it (i.e., RL) then going through all the machinations is worth it but this is just a game.  If you do what you suggest and look for the lowest descent rate experiementally you'll actually be looking at the speed for minimum sink rate which is not the same as best glide.  Minimum sink rate is great if you're in a 163 and want to loiter at altitude over a protected target waiting for bombers to arrive but it's a function of time not distance.  Best glide is a function of distance so you need more than just sink rate data and best glide (L/Dmax) is a bit faster than minimum sink rate speed.

As for determining speed for best rate of climb (Vy) for a prop plane the that speed occurs at C_L^3/2/C_D.  That makes thing really clear doesn't it  .  Vy is based on excess power which can be measured by level acceleration or saw-tooth climb flight tests although I'm sure someone has a program somewhere that will help determine it.  All that said, since HT has said that the default values for Auto-speed are best sea level climb rate that should be Vy.