Maximum Altitude ?

The stated max altitude above sea level of the A10 is supposed to be 45,000 feet yet no matter what I do I cannot get much above 30,000. I have tried running completely clean and with very little fuel (like 5 percent) and still cant make it that high. Now I know I probably just have too much time on my hands, but can someone help me out here ?

I either end up stalling (even at a minimum rate of climb), or having dual engine failure ( I assume because of the tempature at altitude)...

"The sold intention is learning to fly, condition grounded but determined to try, cant keep my eyes from the circling skies...."

I managed 39199 before. I then ejected and got up to 600knots so that was two impressive stunts in one day. (Ok, not impressive but....)

You should turn APU on > 20000 feet. Jettison all weapons, and have plenty of fuel for the ascent. 1 degree up bubble. Slow and steady...

Dont forget to check your oxygen flow. You'll get hypoxic effects above 20000 if its not on.

Is the APU regularly used above 20k feet?

I always spooked around there without it and am wondering about the background.

Saving engine thrust from the generators? Prepare for an engine flameout?

Supersheep

Is the APU regularly used above 20k feet?

I always spooked around there without it and am wondering about the background.

Saving engine thrust from the generators? Prepare for an engine flameout?

 

 

Supersheep

No it's not, the APU is ONLY used real world in flight for emergency's. Now, I've had pilots fly a 2 or 3 hour mission and forgot to turn it off. It doesn't hurt anything, just burns extra fuel and shortens the lifespan of the APU.

The ONLY items the -1 talks about when over 20,000 feet are:

Emergency Procedures, Cockpit Electrical Fire

.....Although engines have operated successfully under ideal conditions at

altitudes above 20,000 feet, consideration should be given to maintaining a lower altitude. Below 10,000 feet, suction-feed will be adequate for all

operating conditions.

and

Emergency Procedures, Double-Engine Failure

If both engines fail during flight at high altitude (above 20,000 feet MSL), the decision must be made whether to trade altitude for airspeed

to try a windmill start using the WINDMILL AIR-START procedure, and/or to glide down to a lower altitude to start the APU for an assisted start.

lastly

APU Start

The APU is designed to start at altitudes up to 15,000 feet. However, the APU has been started at altitudes up to 20,000 feet.

I have always been skeptical about height limitations in ED products, since the original Lock on. That aside, when climbing to great altitudes, you really need to bring the speed with you, there's no point in being at 30k ft @ 170 knots, you have no energy to work with. If I were to reach for the skies, I would do the following: TO with about 70-80% fuel. Climb slowly to 20 000 at an angle of about 3 deg after 10 000. When at 20 000, stop climbing and engage autopilot. Increase airspeed until you simply can't increase it any more. Initiate a new climb, at max 2 deg, use autopilot for stability. Level out and increase airspeed whenever necessary, ie, don't let it sink below 220 knots. When it gets difficult to maintain this, decrease climb angle to 1 deg, and take your time. All this takes a looong time, and you will slowly burn away the fuel you started with. I did 41 000 with this tactic once, flew across almost the entire map in the process. So you need patience..

maximum i got was only 32000 , any higher the aircraft stalls out

Weather type probably and should affect the maximum altitude, have you tried using DW and setting up the most favorable conditions? A bit like cheating perhaps, but...

I might try this again tonight to check my own number, and see what experiences I might come across....

I will do the following for later reference:

Weather: default normal weather (zero wind, zero turbulance)

Temperature: 0 deg

Configuration: 80% fuel, and nothing else

Flight plan: TO @ Batumi, set course for crimea. When nearing crimea, make a slow and energy conserving turn towards the east. When maximum altitude is reached, do a 90 deg dive for the earth at full throttle just for the fun of it and see what speed can be reached. (its a sim after all :D ). Will report back later...

Edit: think I'll do 100% fuel

Now, I've had pilots fly a 2 or 3 hour mission and forgot to turn it off.

Thank the gods I'm not the only one to do that... :D

I have always been skeptical about height limitations in ED products, since the original Lock on.

While no desktop simulator will ever be perfect in this regard, do remember that "service ceiling" and that type of characteristics should also be critically considered: they always depend on conditions that may or may not be openly stated in the source being referenced. Air temperature can, for example, change your expected ceiling by thousands of feet. (Refer to -1 for details.)

While no desktop simulator will ever be perfect in this regard, do remember that "service ceiling" and that type of characteristics should also be critically considered: they always depend on conditions that may or may not be openly stated in the source being referenced. Air temperature can, for example, change your expected ceiling by thousands of feet. (Refer to -1 for details.)

Indeed it can, and I'm aware of this, so I didn't and won't claim anything, since I have no expertise or relevant experience to really state anything about it, but I still have this feeling (the force is strong in me)...

BTW: What is this mysterious "-1" you and Paulrkii mention? I guess it's some kind of military document?

The pilot manual for the A-10. (Well, one of the manuals pilots use.)

Wait, there's life above 500' off the deck? What's the fun in that? In fairness, I actually do standoff with weapons and employ form 16-18,000' MSL when dictated by threat profiles. It's just so much more fun on the deck.

Here's my report:

I managed to get to 40 500 ft at which point I stalled. I still had about 30-40% fuel left, and when I think about it, I should have waited with the final leg until I had 5% perhaps, I might have made it to 41 000. These where the conditions:

Temperature: 0 deg celsius

QNH: 756

0 wind/turbulence

Flight time: 2.5 hours

Ran out of fuel when pre-contact was established with tanker:doh:.

How: After reaching about 25 000 ft, I leveled out and invreased arispeed as much as I could, then I set a climbrate of 500 ft/min, and leveled out again once I had lost 10 knots of airspeed, repeated until I got to 30 000, from there I only used a climbrate of 250 ft/min, but otherwise the same tactic.

I also found out that the HUD does not show altitudes above 38 000 ft (why?), but the gauge was still working, luckily.

Conclusion: I think it is possible to reach 45 000 or higher if you were to set the lowest temperature allowed in the sim.

Here are some screens if I may:

@40 500 ft at which point I stalled, look at the barometic gauge, as the HUD is no longer giving altitude.

@40 000 ft, as you can see, I had 120 IAS and where flying happily (the speed was stable and not decreasing at level flight)

Here's the view form 35 000 ft:) (on the way down again)

The pilot manual for the A-10. (Well, one of the manuals pilots use.)

Yep, the "Dash-1" is the "Owner's Manual" for any USAF aircraft .. very good reading .. too bad they don't have it for the Kindle :smartass:

Depending on the regulatory body, and the specific limitation in question (combat ceiling, service ceiling, absolute ceiling), the answer and technique used to acheive the limit can be different.

Generally, if you want to find out how high the airplane will really go, you CANNOT simply climb with a fixed vertical speed and keep going until you stall; that won't get you the desired results.

You need to climb at a fixed thrust with a constant airspeed until reaching the desired mach at the "changeover" altitude, then maintain a fixed mach as airspeed decreases during the climb. When the rate of climb is reduced to 100fpm, you've made it to the service ceiling.

Do the same thing until the climb rate is zero, and you've reached the absolute ceiling.

I don't remember what the exact definition of a combat ceiling is (since we don't exactly BFM the CRJ), but since you'd need to have a sizable margin available for maneuvering, I'd expect it to be significantly lower than either of the above.

hmm, nice to see a solid definition, wish I knew that before I did my 2.5 h flight. :doh:

How do you figure out what the desired mach is? and is there any way to get a mach readout in the a-10?

If I may comment on APU's. I do not know what the dash-1 says about the A-10C specifically. However, I am more familiar with civil airline operations.

There seems to be a common misconception that APU's run only during emergencies while airborne. What is true is that APU's are used only during emergencies, but they often run at other times.

There are two considerations that need to be realized (and are often not realized) regarding APU's. First, the APU has a poorer track record for service reliability than the turbojets powering the aircraft. This means that the APU is far more likely to turn on when you need. Secondly, APU's like your turbojets, do not start reliably at high altitudes.

So for civilian aviation, there are circumstances where your APU must run during flight even if you do not plan to use the APU. The best example I can think of is ETOPs operations that require the APU to be on upon entry in to a track. This essentially is to ensure that the APU is able to be started and is running properly so that it may be used if your in the middle of the Atlantic.

Please understand, I do not mean to imply that the A-10 needs the APU on when over water. I do not know what the dash-1 says and what the limitations are on the APU. However, these aspects of APU use seem to often be forgotten.

How do you figure out what the desired mach is? and is there any way to get a mach readout in the a-10?

Desired mach I don't know off the top of my head, but again the -1 is your source. I don't have time to look through it atm though.

Regarding your own mach number indication:

CDU POS INFO page, there you have a MACH entry. (DCS manual, page 179)

CADC page (page 217)

Of course, easier on the HUD - enter IFFCC Test menu during your startup (or during flight), then display mode, then airspeed. Options are TAS, GS, MACH/IAS, and IAS. (pages 360-362)

Thanks etherealN, I should do another flight, but I won't get the chance until after new year sometime. In the meantime, I'll make sure to check out the dash-1 :)

If I may comment on APU's. I do not know what the dash-1 says about the A-10C specifically. However, I am more familiar with civil airline operations.

 

There seems to be a common misconception that APU's run only during emergencies while airborne. What is true is that APU's are used only during emergencies, but they often run at other times.

 

There are two considerations that need to be realized (and are often not realized) regarding APU's. First, the APU has a poorer track record for service reliability than the turbojets powering the aircraft. This means that the APU is far more likely to turn on when you need. Secondly, APU's like your turbojets, do not start reliably at high altitudes.

 

So for civilian aviation, there are circumstances where your APU must run during flight even if you do not plan to use the APU. The best example I can think of is ETOPs operations that require the APU to be on upon entry in to a track. This essentially is to ensure that the APU is able to be started and is running properly so that it may be used if your in the middle of the Atlantic.

 

Please understand, I do not mean to imply that the A-10 needs the APU on when over water. I do not know what the dash-1 says and what the limitations are on the APU. However, these aspects of APU use seem to often be forgotten.

I told you exactly what the 1A-10c-1 states and we only run the APU in flight for emergencies. We aren't talking civilian Acft we're talking the A-10.

I told you exactly what the 1A-10c-1 states and we only run the APU in flight for emergencies. We aren't talking civilian Acft we're talking the A-10.

I understand and that's why I tried to make this clear. I was trying to clarify principle's with APU management. I do not fly A-10C's and combat aircraft are markedly different than civillian. However, I've seen so many misconceptions with APU principles that I wanted to note some of these points.

Every Dash 1 I've ever come across has been referred to as "the big blue sleeping pill". Not "good reading" lol.

Depending on the regulatory body, and the specific limitation in question (combat ceiling, service ceiling, absolute ceiling), the answer and technique used to acheive the limit can be different.

 

Generally, if you want to find out how high the airplane will really go, you CANNOT simply climb with a fixed vertical speed and keep going until you stall; that won't get you the desired results.

 

You need to climb at a fixed thrust with a constant airspeed until reaching the desired mach at the "changeover" altitude, then maintain a fixed mach as airspeed decreases during the climb. When the rate of climb is reduced to 100fpm, you've made it to the service ceiling.

 

Do the same thing until the climb rate is zero, and you've reached the absolute ceiling.

 

I don't remember what the exact definition of a combat ceiling is (since we don't exactly BFM the CRJ), but since you'd need to have a sizable margin available for maneuvering, I'd expect it to be significantly lower than either of the above.

Ok, I've been trying to wrap my head around this today, but I'm afraid I need some additional education.

I found from the 1A-10A-1 (Supplement part 3 - Climb) that:

Combat ceiling = 500 FPM

Cruise ceiling = 300 FPM

Service ceiling = 100 FPM

Absolute ceiling = 0 FPM (Wikipedia)

About the "changeover altitude" I'm still wondering a bit. I've read a good portion of the -1 and I've found nothing about it. Otherwise on the mighty Internet, it is indeed explained as the altitude where the desired mach is reached when climbing with constant IAS. I found a good forum post by a pilot that explains it a bit, and he goes on to say that "it is easily calculated" but says nothing more.:doh: But then another post says this mach number is usually between .78 and .79 (oddly specific). The maximum operational mach number for the A-10 seems to be .75 (from the -1). Perhaps this then is the DMN?

So to summarize; to reach the different ceilings for any given setting (drag index, weight, temperature, and so on) I would:

1. Climb with a constant IAS (any you can keep constant will do? perhaps 190 IAS then?)

2. When reaching mach 0.75, (@ changeover altitude) keep adjusting climb rate so mach stays constant

3. a When the climb rate reaches 500 FPM, I have reached the combat ceiling

b When the climb rate reaches 300 FPM, I have reached the cruise ceiling

c When the climb rate reaches 100 FPM, I have reached the service ceiling

d When the climb rate reaches 0 FPM, I have reached the absolute ceiling

It's really the desired mach number I'm still unsure and wondering about. I have done quite some searching and reading of the dash -1 and found nothing (it can indeed be quite boring sometimes), and if someone could reference this number for me, it would be very cool.

What are your weather settings?

I'm sorry I didn't take the time to read all the post. A lot of manuals and charts for aircraft performance are based on a standard day. That is 15C and 1013.25 milibars of mercury at sea level. I hope this helps with testing. If it already hasn't be said.