Doesn't A-10C feel more flight capable in real life?

[Chefen41]

As I recall from flight training, the indicated airspeed at which an aircraft stalls can be considered constant, but the true airspeed at which it stalls increases with altitude.

 

I have only flown gliders, someone might have paid more attention to this topic than me ;-)

[bbrz]

Damn was I wrong. Apologies to bbzr, way off base pal. I'll stick to my guns on negative lift though.

No problem, but your negative lift theory is still wrong. The A-10 in your example/explanation uses NACA 6716 and 6713 airfoils.

 

The 6716 has a CL of 0.7 at 0deg AoA and even at -6deg AoA CL is still positive (0.15).

Edited September 24, 2019 by bbrz

[bbrz]

But as long as a pilot operators handbook gives a stall speed as an absolute KIAS value (or mph or kph or whatever, as long as it's IAS) and does not advise to take altitude or density altitude into account, that's really good enough for me.

Since neither e.g. a C-152, F-15 or 747 manual features such notes, the question to =4c=Nicola is, if stall speed increases with altitude, how much does it increase at e.g. 10000ft? 1%? 10%? 50%?

 

Another point concerning these 'fixed' stall speeds is, that they are usually only valid at the most forward CG, which means that with the CG moving aft, stall speed decreases.

Edited September 24, 2019 by bbrz

[eaglecash867]

You obviously do not understand aerodynamics good enough.

 

I understand aerodynamics well enough to know that it doesn't have anything to do with how IAS is derived in an airspeed indicator, and that stall speed on that indicator is not on a sliding scale based on altitude. You are free to believe what you want to believe, and post false information all you like. This is only a sim site, so you're not going to hurt anybody by doing that. When someone here goes out and wants to learn to fly in the real world, they'll find out very quickly what IAS is and how its derived. So, no harm done. You're not the first person to get IAS and TAS and/or CAS confused, and you won't be the last. Its all good. :thumbup:

Edited September 24, 2019 by eaglecash867

[eaglecash867]

As I recall from flight training, the indicated airspeed at which an aircraft stalls can be considered constant, but the true airspeed at which it stalls increases with altitude.

 

I have only flown gliders, someone might have paid more attention to this topic than me ;-)

 

That would be correct. Nikola is confusing IAS with TAS. :)

[eaglecash867]

You suffer from Dunning–Kruger effect. Do you believe earth is flat?

 

Again, straying off the topic. The shape of the Earth also has nothing to do with IAS vs. TAS. :megalol:

[eaglecash867]

People that suffer from Dunning–Kruger effect usually believe Earth is flat, that's why I asked that.

 

Yes, I know. You were getting personal, and there's no need to do that. You are confusing IAS with TAS. Full stop.

[bbrz]

I assume that =4c=Nikola is talking about the small increase in stall speed due to the lower achievable AoA at (very) high altitudes, basically due to the lower Re-number and higher Mach number.

 

Since nose radius, vortex generators etc. do have an effect as well, I'll ask =4c=Nikola again, how much does the stall speed increase with altitude?

 

Or more suitable in this OT discussion; Does the stall speed noticeable increase with altitude?

[bbrz]

Sorry, missed that. I hate reading forum posts on tiny mobile phone screens.

[bbrz]

Transport aircraft designers/manufacturers (Boeing/Airbus...) usually do not specify high altitude stall speed because low speed buffet onset is violent enough to deter you.

Not only transport category aircraft. This applies to e.g. the F-15C as well. The stall speed table specifically says for the power off stall speed: all altitudes

[Habu23]

Here is some truth data from a few days ago flying a real A-10. Can someone please configure an A-10, from left to right, as follows and see what your airspeed is with the following loadout and parameters:

 

 

 

1150 rnds TP, 9500lbs gas, 1xLAU-105 with 1x CATM-9 STA 1, rocket pod STA 2, single Mavs on LAU-117's STA 3 & 9, 2xTER's of BDU-33's STA 4 & 8, 1xLITENING TGP STA 10

 

 

I was flying 310-315 KIAS with the following parameters:

 

 

Max throttles gave me 3000 lbs/hr each side, 830 ITTs, Fans 85%, 4,500 ft MSL with altimeter 30.24 set on the ground to account for density altitude, 26C for temperature at sea level.

 

 

I was able to hold 310-315 KIAS with this IRL data and simply wrote down what the gauges said. Someone please compare to DCS as I am away from my PC and let me know. Just so you all know, the key indicator to look for is fan % and then ITT's. The fan gauge is a direct indication of engine thrust output and is used almost exclusively on takeoff roll to insure our takeoff data is valid and that we can safely climb away with one engine if it fails immediately after rotation.

 

 

 

After conducting this test, drop down to 500 AGL and fly 300 KIAS. Perform a loaded roll in any direction with the TVV between 0 and 5 degrees (turn level turn safe escape maneuver). You should not get any tones (potentially steady but definitely no chopped) until about 5G's at least for the first 60 degrees of turn. I performed this maneuver that day as well.

 

 

 

Habu

Edited September 27, 2019 by Habu23

[nighthawk2174]

Upon immediate testing:

 

fan is just over 80%, 790 ITT, just over 3000lbs/hr, speed held steady at 298 kts

 

 

 

edit: for second test got tone right before 4g (probs 3.8ish) and could not even get to 5g, maxed out at 4.4ish at which point the choppy tone was in full swing. Any attempt to pull harder leads to immediate choppy tone and heavy wing rock.

Edited September 27, 2019 by nighthawk2174

[lobo]

 

I was flying 310-315 KIAS with the following parameters:

 

 

Max throttles gave me 3000 lbs/hr each side, 830 ITTs, Fans 85%, 4,500 ft MSL with altimeter 30.24 set on the ground to account for density altitude, 26C for temperature at sea level.

 

Habu

 

 

Thanks for this info.

 

Questions:

 

1) OAT 26 degrees... was this as read from the CDU?

 

2) The IAS you were reading from the steam gauge or the HUD?

 

3) When you do the level turn how fast are you increasing the G? 1 G/sec rate or 2?

 

In the sim, with no seat of the pants visceral feeling, and a short throw control stick, it is extremely easy to go stop to stop with the controls... something that in R/L you would be less inclined to do (certainly for pitch).

 

Thanks

Edited September 28, 2019 by lobo**

[Habu23]

Thanks for this info.

 

Questions:

 

1) OAT 26 degrees... was this as read from the CDU?

 

2) The IAS you were reading from the steam gauge or the HUD?

 

3) When you do the level turn how fast are you increasing the G? 1 G/sec rate or 2?

 

In the sim, with no seat of the pants visceral feeling, and a short throw control stick, it is extremely easy to go stop to stop with the controls... something that in R/L you would be less inclined to do (certainly for pitch).

 

Thanks

 

 

1) 26C from the weather shop for the airfield, so just set this in the editor for temperature.

 

 

2) IAS from the HUD

 

 

3) 4G loaded roll within 2 seconds but we are always able to beat those assumptions with safe escapes based on muscle memory so we can usually do it in about 1 second.

[lobo]

"Can someone please configure an A-10, from left to right, as follows and see what your airspeed is with the following loadout and parameters:"

 

My results below.

 

Temp 26c in mission editor.

Altimeter 30.24

 

1150 rnds TP, 9500lbs gas, 1xLAU-105 with 1x CATM-9 STA 1, rocket pod STA 2, single Mavs on LAU-117's STA 3 & 9, 2xTER's of BDU-33's STA 4 & 8, 1xLITENING TGP STA 10

 

Max power @4500' gives me:

Speed 291 KIAS sustained vs RL 310-315 KIAS

FF 2900 lbs/hr each side vs RL 3000 lbs/hr

ITTs 790 vs RL 830 ITTs

FANs 81% vs RL Fans 85%

 

500 AGL and fly 300 KIAS. Performed a loaded roll with the TVV between 0 and 5 degrees. Steady tone at 4.2-4.3G after turning approx. 40 degrees. vs RL 5G's at least for the first 60 degrees

 

Notes

1: Pulling any more than this resulted in the chopped tone. In order to sustain any further turn beyond 40 degrees have to reduce G significantly due to rapid speed bleed off.

2: Wonder if this may be a drag (weapon) calculation issue? When I fly the same profile with no external stores, I get steady tone at 4.8G chopped at 5. Able to turn much more also...

3: I read they have been adjusting drag on some of the F/A-18 weapons and pods... maybe the Hawg needs some attention in this area?

Edited September 28, 2019 by lobo**

[bbrz]

Wonder if this may be a drag (weapon) calculation issue? When I fly the same profile with no external stores, I get steady tone at 4.8G chopped at 5. Able to turn much more also...

That's likely, but still a bit strange since the DCS A-10 matches (and even exceeds) the -1 performance date in clean configuration with the too low N1.

[A10Yoda]

That's likely, but still a bit strange since the DCS A-10 matches (and even exceeds) the -1 performance date in clean configuration with the too low N1.

If you look at my earliest comments here, that has been my belief as well..Strange a former A10 pilot would notice things like that...which seems counter to some of the other comments.

 

 

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[KTFBGB]

Well I would say that’s pretty damn close. All numbers are within 4-5% between sim and real A-10. It has been said in the past that ED has to reduce some of the values per contracts with DOD or whoever they may be. I would say that we are getting our moneys worth. Especially if they are required to reduce some values. 4-5% difference on a sample size of 2 is basically statistically insignificant.

[bbrz]

It has been said in the past that ED has to reduce some of the values per contracts with DOD or whoever they may be.

In this case the clean performance would be lower as well.

[eaglecash867]

I would say that we are getting our moneys worth. Especially if they are required to reduce some values. 4-5% difference on a sample size of 2 is basically statistically insignificant.

 

Completely agree. Its a sim that gives us a reasonable amount of fidelity, and it only cost 60 bucks.

[David OC]

Completely agree. Its a sim that gives us a reasonable amount of fidelity, and it only cost 60 bucks.

 

Reasonable..Very reasonable if you consider what is modelled.

 

So, Title

"Doesn't A-10C feel more flight capable in real life?

Yes, it's real life and this is a very very close interpretation of irl for 60 bucks lol.

[Habu23]

Based on the above tests and my own (I was able to open up the sim on the weekend) there are certainly some issues that as an A-10 driver deserve some attention. First, 4-5% difference in fans with the lower ITT means that the engines are positively downrated. This is not as big of an issue as the second issue: energy bleedoff and AoA issues on a turn level turn safe escape maneuver, possibly drag model related. Currently it is impossible to do a proper turn level turn safe escape maneuver with the A-10C in DCS. This is important because low altitude bomb events will likely lead to the jet being fragged on level releases and possibly 10 LAHD deliveries. Obviously, that is not happening right now, but if bomb frag and damage is revisited at a later point, this will be an issue and ruins a bit of immersion. The jet is currently too sluggish for me to recommend low altitude tactics with the A-10C currently in DCS.

 

 

 

I hope the truth data and these recommendations will answer all questions and be a starting point to make the A-10 an even better representation in DCS. I think it is worth the developer's time to address these two issues in some way, in addition to the GAU-8 dispersion which belongs in another thread but should be looked at.

 

 

Habu

[lobo]

Based on the above tests and my own (I was able to open up the sim on the weekend) there are certainly some issues that as an A-10 driver deserve some attention. First, 4-5% difference in fans with the lower ITT means that the engines are positively downrated. This is not as big of an issue as the second issue: energy bleedoff and AoA issues on a turn level turn safe escape maneuver, possibly drag model related. Currently it is impossible to do a proper turn level turn safe escape maneuver with the A-10C in DCS. This is important because low altitude bomb events will likely lead to the jet being fragged on level releases and possibly 10 LAHD deliveries. Obviously, that is not happening right now, but if bomb frag and damage is revisited at a later point, this will be an issue and ruins a bit of immersion. The jet is currently too sluggish for me to recommend low altitude tactics with the A-10C currently in DCS.

 

 

 

I hope the truth data and these recommendations will answer all questions and be a starting point to make the A-10 an even better representation in DCS. I think it is worth the developer's time to address these two issues in some way, in addition to the GAU-8 dispersion which belongs in another thread but should be looked at.

 

 

Habu

 

+1 to what Habu says above. :thumbup:

 

It would be great if someone could run this up the ED chain and see what comes of it.

 

The ED A-10C is a fantastic, mature sim which could possibly be tweaked to make it even better!

[A10Yoda]

+1 to what Habu says above.

 

It would be great if someone could run this up the ED chain and see what comes of it.

 

The ED A-10C is a fantastic, mature sim which could possibly be tweaked to make it even better!

With 13 years between the last time I flew the A10 I cannot say the engine performance is off. However if Habu is currently flying it I would easily take his word on it.

 

The drag issue in my opinion seems to be a little more where I would ask them to focus their attention as that could matter for several of their flight modules..

 

 

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[Phantom_Mark]

Great to see input from real A10 pilots here, the A10C is among my most favourite modules, thanks for trying to help make it better :)