Squiz
Mar-30-2014, 19:38
There has been an ongoing problem with AI aircraft in formation at high level, particularly as they descend. At seemingly random times during a descent, the wingmen begin to twitch and a short while later they perform a confetti break, darting all over the sky, sometimes colliding with each other and often (but not always) reforming at low level prior to landing. The twitching occurs when an aircraft starts a sequence of full up elevator, full down elevator, full up elevator and then level elevator before starting the sequence again. You can observe this if you follow a twitching aircraft in external view.
Each type of AI aircraft performs its antics differently and at different stages during a similar flight plan which make detailed investigation very difficult.
I noticed that during a turn of an He-111 formation of nine aircraft at 7,000 metres, the two outside aircraft began to twitch indicating that they had seemingly reached a limiting airspeed whilst trying to keep up with the leader.
I lowered the default airspeed from 300 kph to 270 kph and the twitching stopped.
Again, to descend an AI He-111 formation from 7,000 metres at 300 kph without them breaking formation, steps of no more than 200 metres must be planned in the FMB. I then found that if the formation is slowed to 200 kph just before descent and the descent is planned at 200 kph then the steps can be increased to 500 metres between 7,000 and 5,000 metres and then one final step can be made to 500 metres before the aircraft land. (20% fuel and no weapons except guns).
I found that each aircraft has a different IAS at which twitching occurs and that this IAS decreases with increased height (probably related to TAS).
The rate of descent seems quite high during an AI descent and the aircraft speed builds up rapidly hence the need to level off and slow down to 200 kph at each descent step before the aircraft reaches its twitch speed. Added weapons and fuel load will increase the rate of descent, as well as the speed and the likelihood of a formation break up. However when the aircraft is hand flown within the formation, no such limitation occurs even if the rate of descent (and therefore the speed) is increased significantly beyond that of the AI aircraft.
All aircraft on both sides are affected, some more than others. Fighters are very prone to formation breakups and conversely, those with high drag profiles such as the Condor needs very few descent steps, if any, to maintain formation.
Another example is a formation of fully loaded Ju87s climbing from 3,000 metres to 5,000 metres at the default airspeed of 300 kph. The climb IAS is around 200 kph and when level at 5,000 metres, the aircraft accelerate. When passing 250 kph, the formation breaks up. However, at a reduced speed of 240 kph, the formation will climb and cruise normally. An anomaly occurred in that when the aircraft tried to re-join formation, they reach speeds of 300 kph without control problems. Additionally, when the aircraft entered the bombing dive with speed brakes out, the IAS rose to 550 kph without any apparent twitching or adverse formation effects.
The problem could be partially solved if the default rates of descent in AI aircraft could be significantly reduced. A permanent fix would require the total removal of the limiting “twitch speed” in each AI aircraft.
The problem will be posted in Bug Tracker.
Each type of AI aircraft performs its antics differently and at different stages during a similar flight plan which make detailed investigation very difficult.
I noticed that during a turn of an He-111 formation of nine aircraft at 7,000 metres, the two outside aircraft began to twitch indicating that they had seemingly reached a limiting airspeed whilst trying to keep up with the leader.
I lowered the default airspeed from 300 kph to 270 kph and the twitching stopped.
Again, to descend an AI He-111 formation from 7,000 metres at 300 kph without them breaking formation, steps of no more than 200 metres must be planned in the FMB. I then found that if the formation is slowed to 200 kph just before descent and the descent is planned at 200 kph then the steps can be increased to 500 metres between 7,000 and 5,000 metres and then one final step can be made to 500 metres before the aircraft land. (20% fuel and no weapons except guns).
I found that each aircraft has a different IAS at which twitching occurs and that this IAS decreases with increased height (probably related to TAS).
The rate of descent seems quite high during an AI descent and the aircraft speed builds up rapidly hence the need to level off and slow down to 200 kph at each descent step before the aircraft reaches its twitch speed. Added weapons and fuel load will increase the rate of descent, as well as the speed and the likelihood of a formation break up. However when the aircraft is hand flown within the formation, no such limitation occurs even if the rate of descent (and therefore the speed) is increased significantly beyond that of the AI aircraft.
All aircraft on both sides are affected, some more than others. Fighters are very prone to formation breakups and conversely, those with high drag profiles such as the Condor needs very few descent steps, if any, to maintain formation.
Another example is a formation of fully loaded Ju87s climbing from 3,000 metres to 5,000 metres at the default airspeed of 300 kph. The climb IAS is around 200 kph and when level at 5,000 metres, the aircraft accelerate. When passing 250 kph, the formation breaks up. However, at a reduced speed of 240 kph, the formation will climb and cruise normally. An anomaly occurred in that when the aircraft tried to re-join formation, they reach speeds of 300 kph without control problems. Additionally, when the aircraft entered the bombing dive with speed brakes out, the IAS rose to 550 kph without any apparent twitching or adverse formation effects.
The problem could be partially solved if the default rates of descent in AI aircraft could be significantly reduced. A permanent fix would require the total removal of the limiting “twitch speed” in each AI aircraft.
The problem will be posted in Bug Tracker.