Very frustrating flight, Su-27 instant action - Gauntlet

[SAABoy]

Hey everyone, hoping for some quick advice.

 

I'm doing this instant action mission but having a really hard time turning my su-27. I can post a trk file if needed but I'm hoping for some 'no-duh' advice. It seems like anytime I try to pull the stick my speed drops quickly until I eventually get a 'minimum speed' warning; almost as if there's some autopilot or g-limiter on. Very frustrating! Brake, gear, and flaps aren't deployed, autopilot is off. I frequently use ALT+3 for autopilot when checking radar or comms and then pretty A (autopilot key) to deactivate before resuming maneuvers. Is this bad practice? I haven't had issues with this habit in other training missions but I have no idea what else could be going on.

[Mars Exulte]

Speed needs to be above 400kmh for gentle turns above 600kmh for anything resembling a sharp turn. That low speed warning should be self descriptive. You're pulling too hard on the stick and stalling out. Flankers especially, but most fighters, can generate very high AoA in turns, causing a rapid speed bleedoff. Energy management is a key aspect of air combat and maneuvering.

 

Also, I'd suggest setting some curves on your pitch and roll axises to help with precision if you're using a short stick. Start with 20 or so and adjust up or down according to taste.

Edited September 29, 2019 by zhukov032186

[DarkFire]

In anything other than direct control mode (activated by hitting S) the automatic control system does have a built-in combination AOA and G limiter. That being said, the limiter is designed only to prevent you from exceeding airframe G-load limits at a specific configuration weight (IIRC 23,500 Kg). The limited in the Su-27S which we have in DCS does not dynamically adjust for all-up weight i.e. stores and current fuel weight. It is therefore possible at extremes of weight & speed to exceed the ability of the limiter. In most circumstances though it will save you no matter what you do. It's also true that the limiter takes a fraction of a second to operate so care is needed with instantaneous G-loading of the airframe.

 

Next consideration: the Su-27 does not have what most people would call an autopilot. The automatic control system is always engaged (unless operating in direct mode). The "autopilot" modes uses the trim system to maintain altitude, attitude etc. The system naturally also has limits and outside of certain parameters will disengage.

 

The fact that the ACS uses the trim system is important: even if you disengage the "autopilot" the effective centre position of the control surfaces will not necessarily be the true centre value but rather a centre value that's been moved by the ACS "autopilot" trim system. It's therefore the case that even though the "autopilot" is off, maximum available control deflection is not 100% of the theoretical value. The way to deal with this, and it's particularly relevant before entering combat, is to turn off the "autopilot" and then reset the ACS (I can't remember the key combo off hand) - this resets the ACS internal trim level to default, restoring 100% of available manual control deflection.

 

Last point: what's your entry speed for the turns? Corner speed in the Flanker depends on several factors but is generally in the vague region of 720-750 Km/h to get that sweet 23 degrees per second sustained turn rate. The Flanker, especially when fully loaded with fuel & missiles, will heavily bleed speed in tight turns because it's such a huge lump of an aircraft so you have to be very careful in managing your speed during the turn. It's very easy to get to the point where you're actually pointing the nose using increased AOA rather than keeping up the turn rate.

[Ironhand]

... I haven't had issues with this habit in other training missions but I have no idea what else could be going on.

 

Others have touched some high points but...

 

Out of curiosity? What’s your altitude? The higher you are, the faster you have to actually go to hit your maneuvering speed targets. And the faster you go, the greater the inertia, etc. So turning at high altitudes is not quite the same as maneuvering at lower altitudes.

[hornet1a]

This instant action mission start in the air at about 12500 meter (about 39.000ft) that's quite high!

 

 

Here is this same mission but you start at about 6500 meter:

Su-27 - Caucasus - Gauntlet edit 6500 meter alt.zip

[DarkFire]

This instant action mission start in the air at about 12500 meter (about 39.000ft) that's quite high!

 

Here is this same mission but you start at about 6500 meter:

 

Yes, 12,500m is a crazy altitude at which to try ACM in a fully loaded Su-27. The only reasons to be that high are efficient transit cruise or to be at Vmax, since 12,500m is actually the optimum altitude for a max speed run in the Flanker.

 

6,500m is much more sensible for actual combat.

[Ironhand]

Well... you do have 3 wingnuts tagging along in the mission. So I don’t think it was designed to be a CAC mission.

[DarkFire]

Well... you do have 3 wingnuts tagging along in the mission. So I don’t think it was designed to be a CAC mission.

 

Ah I'd forgotten that, been ages since I played that mission.

 

Good advice: use your wingmen freely, even if they only serve to disrupt and distract the enemy.