Power Problem

I am not new to the A-10c.I have enjoyed many hours of fun with it. That said, I used to be able to take off with a full load of Mavericks and GBU 12s in the A10C from just about any place on the Caucasus map. Lately that has all changed. I can’t get enough airspeed (around 125 knots which is what it used to fly at) to lift off even from Batumi with a full load. I use a Warthog stick and throttle with MFG Crosswind pedals.

I have checked calibration on the brakes and throttle and all seems to be normal. It feels like the brakes are dragging or something, or the engines not developing the same power they used to even though the throttle calibrates ok. I have noticed that the airspeed takes a while to get passed 50 knots and builds much more slowly than it used to. When I do reach 125 knots and pull back on the stick to rotate, it doesn’t even start to rotate. ( It used to) The elevator is responding normally though. Has anyone noticed this also?

I tried with 6 mavs + 10 gbu12 and full fuel ( weight overloaded 107% ) - take off ok from Batumi with standard weather and start from runway (so no wind from back).

Rotate 130knots - take off 143.

....Lately that has all changed. I can’t get enough airspeed (around 125 knots which is what it used to fly at) to lift off even from Batumi with a full load. I use a Warthog stick and throttle with MFG Crosswind pedals.

 

I have checked calibration on the brakes and throttle and all seems to be normal. It feels like the brakes are dragging or something, or the engines not developing the same power they used to even though the throttle calibrates ok. I have noticed that the airspeed takes a while to get passed 50 knots and builds much more slowly than it used to. When I do reach 125 knots and pull back on the stick to rotate, it doesn’t even start to rotate. ( It used to) The elevator is responding normally though. Has anyone noticed this also?

Uhhh..no.. full payload takeoff speed is going to be around 155 knots or more.. Kinda has been and will continue to be.

125 knotts will allow you to rotate if you are light on fuel, ammo and payload.

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Thanks guys

I may be remembering the speed wrong, but I seem to remember being able to take off from Batumi with big load outs. I can only get about 125 to 130 kts by the end of the runway.

I did notice that the engines only go to about 94% but not to 100.

Been flying the F-18 too long and getting use to all the power I guess.

I cant get close to 155 kts before the end of the runway. I also notice it take the airspeed indicator a long time before it starts moving. It starts at 50. The wind is 0. It just doesn't seem to be accelerating as fast as I remember it.

Thanks guys

I may be remembering the speed wrong, but I seem to remember being able to take off from Batumi with big load outs. I can only get about 125 to 130 kts by the end of the runway.

I did notice that the engines only go to about 94% but not to 100.

Been flying the F-18 too long and getting use to all the power I guess.

 

I cant get close to 155 kts before the end of the runway. I also notice it take the airspeed indicator a long time before it starts moving. It starts at 50. The wind is 0. It just doesn't seem to be accelerating as fast as I remember it.

You're welcome..

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Go into tune axis for the brakes and try inverting...

Go into tune axis for the brakes and try inverting...

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Well, I ran the MFG configurator and I cant believe it but they were out of adjustment. I had been messing around with the big springs on the side of the pedals the other night and I must have knocked them out of adjustment. So my brakes were in effect dragging. Anyways it all good now.

Thanks for all the suggestions.

Go into tune axis for the brakes and try inverting...

You weren't too far from the real issue after all :D

Run up full thrust with brakes on and do not lower flaps to takeoff position until 140 knotts..

 

You're welcome..

 

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Uh no.

BEFORE TAKEOFF CHECKLIST

Step 2. "Flaps - Set for takeoff."

Uh no.

 

 

 

BEFORE TAKEOFF CHECKLIST

 

 

 

Step 2. "Flaps - Set for takeoff."

I stand corrected internet expert..

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Run up full thrust with brakes on and do not lower flaps to takeoff position until 140 knotts..

 

You're welcome..

 

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(if you are forgetting to drop your flaps until 140 knots) A checklist would fix that... :music_whistling:

A checklist would fix that... :music_whistling:

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I know you found the reason, but I would recommend a lower fuel value if you're going to load the thing to the max. Take a sip of fuel in flight if you need maximum fuel.

Definitely check your brake setup and make sure they are releasing completely. Some pedals don't play well with DCS, like the Saitek Combat Pros. It can take a lot of tweaking to get them working right, and even then it's double-tap to make sure the sim got the release input from them. I ended up having to set one pedal toe brake to control both as an alternate to keep from veering off the runway on takeoff and landing, as I never know which brake will still be half on......

That said, I used to be able to take off with a full load of Mavericks and GBU 12s in the A10C from just about any place on the Caucasus map. Lately that has all changed. I can’t get enough airspeed (around 125 knots which is what it used to fly at) to lift off even from Batumi with a full load.

 

snip

 

I have noticed that the airspeed takes a while to get passed 50 knots and builds much more slowly than it used to. When I do reach 125 knots and pull back on the stick to rotate, it doesn’t even start to rotate. ( It used to) The elevator is responding normally though. Has anyone noticed this also?

Not really how it works. 1) The speed you rotate at is not the one you take off with. It's usually about 10kts less than your take-off speed. 2) That speed is dependent on weight, density altitude, temperature, wind, etc and is not static across maps, missions, or loadouts. You can use a bunch of performance charts to figure out not only your rotation speed, but your climb out speed and roll distance. It'll provide you with a better idea of how 'things are done'. Finally, 3) It doesn't take it a while to get past 50 knots, that's just indicated airspeed catching up on the lack of flow given to the probe. Get the CDU to display your ground speed from taxi to roll and you'll see what I mean.

Maybe if you provided us with the mission you can't take off on, or at least its weather data and your weapons/fuel weight, we can help you with specifics. In so far as controls being a possible issue, you can just hit Right Ctrl + Enter to see if brakes or the throttle are actually holding you back, but I kind of doubt it's not just an overweight hog.

Not really how it works. 1)

Maybe if you provided us with the mission you can't take off on, or at least its weather data and your weapons/fuel weight, we can help you with specifics. In so far as controls being a possible issue, you can just hit Right Ctrl + Enter to see if brakes or the throttle are actually holding you back, but I kind of doubt it's not just an overweight hog.

His brakes were dragging.

2) That speed is dependent on weight, density altitude, temperature, wind, etc and is not static across maps, missions, or loadouts.

In this case, you're referring to ground speed, aren't you?

For takeoff speed, AFAIK A-10 pilots really only need to know the speed in KIAS. And in this regard, the only factor to take into account is aircraft gross weight.

Of course in order to calculate the takeoff ground roll as well as continuation and refusal speeds and so on, all of the above plus runway length and runway condition must be taken into account. But the takeoff speed itself only depends on gross weight, and is calculated as indicated airspeed, not ground speed, to the best of my knowledge.

Edit: Oh, and like lobo said, OP already figured it out, the brakes were partly on. ;)

His brakes were dragging.

There must have been an update somewhere in either windows, or something else. I had the same problem and had to reset my T-Flight pedals to default in Windows to get them to STOP dragging.

In this case, you're referring to ground speed, aren't you?

 

For takeoff speed, AFAIK A-10 pilots really only need to know the speed in KIAS. And in this regard, the only factor to take into account is aircraft gross weight.

 

Of course in order to calculate the takeoff ground roll as well as continuation and refusal speeds and so on, all of the above plus runway length and runway condition must be taken into account. But the takeoff speed itself only depends on gross weight, and is calculated as indicated airspeed, not ground speed, to the best of my knowledge.

 

Edit: Oh, and like lobo said, OP already figured it out, the brakes were partly on. ;)

Nah didn't mean GS. An example: in high density-altitudes airfoils require more speed (equating to a larger mass of air) to develop lift, extending the ground roll and requiring a high climb angle if there are obstacles past the runway. I think we're saying the same thing there. Rotation is really all about creating a positive AoA, it's why the front gear tends to feel 'glued' to the runway if the ground roll's unnecessarily extended, but if rotating before Vr the wing will stall and may even cause enough drag for the plane never to reach its climb speed. But takeoff speed is certainly not dependent only on gross weight, it will vary with those variables, and therefore rotation speed is also not only dependent on gross weight. If a headwind can shorten your ground roll, then is weight the only contributing factor? Ground roll, rotation, and climb speed are all linked.

If you're interested, I recommend you check out Stick and Rudder by Wolfgang Langweische, it really helped explain AoA to me.

His brakes were dragging.

Yeah I figured that out after I posted lol, I'll keep that post there since it discusses some unrelated misconceptions, even if my foot's slightly in my mouth at the end.

It looks like you are mixing up GS and IAS. As Yurgon wrote. IAS is the same, regardless of density altitude, headwind etc.

At higher (density) altitude the take off run is longer due to the lower engine performance and due to the higher GS, but IAS will still be the same.

If you e.g. check the A-10 performance tables you will see that the take off speed (IAS) depends only on weight.

I don't know why the nosewheel should be 'glued' to the runway when extending the ground roll. It'S usually the opposite. The higher the speed, the more the aircraft tends to unstick on its own.

If you rotate early, the wing doesn't stall. Why should it? Stall depends only on AoA. If you rotate e.g. to 10deg at 80kts or 180kts, it doesn't make any difference concerning stall.

You should re-read stick and rudder ;)

I don't know why the nosewheel should be 'glued' to the runway when extending the ground roll. It'S usually the opposite. The higher the speed, the more the aircraft tends to unstick on its own.

That's true for a plane like the TF-51. For the A-10, extending the roll past Vr certainly does create a 'sticking' effect. Look at the angle created by a wing's camber with weight on wheels. Compound it with a slight variation in height between the main and nose gear, a forward CoG, or with any kind of leading edge flaps, and an effect is created where the trailing air moves upwards prior to rotation. I'm assuming you're thinking of a ground roll in terms of a straight wing that's parallel to the ground, and therefore during the roll is moving air horizontally until capable of generating the elevator pressure to increase the AoA. That's not the case.

 

You should re-read stick and rudder ;)

you should reread my post lol. it starts off with "No I did not mean GS".

Oh and as for the other stuff, you're speaking in part truths. High density altitudes do affect engine performance, but thrust isn't the only part of that problem. Stalls are governed by AoA, but there is a broader link between the elements I mentioned and AoA. Increasing pitch at low speed absolutely affects AoA and drag adversely affects thrust, like I don't know how you'd even attempt to argue the opposite.

1....an effect is created where the trailing air moves upwards prior to rotation. I'm assuming you're thinking of a ground roll in terms of a straight wing that's parallel to the ground, and therefore during the roll is moving air horizontally until capable of generating the elevator pressure to increase the AoA. That's not the case.

 

2. Increasing pitch at low speed absolutely affects AoA and drag adversely affects thrust.

1. Very weird theories and you are disregarding the most important item, trim. The higher the speed, the bigger the nose up moment (with correct takeoff trim).

Since a wing creates a downwash, when or how does the air move upwards instead?

2. Pitch affects AoA? How? And how does drag affect engine performance (thrust)? Not able to follow these 'theories'.

Am I being trolled here? lol I'm relatively new on the forum so I dunno what this is.

Just in case you're sincere,

Also drag is a force that acts opposite to thrust. This is going to get frustrating for me so I'll stop here.

Am I being trolled here? This is going to get frustrating for me so I'll stop here.

Way too much incomprehensible nonsene. Glad that you stopped here. I'm out as well.