As long as the turn meets the requirements of RRS 44.2, then yes, the turn accomplishes both objectives, no need for a separate penalty turn.

It may be a timing situation as the competitor elected to cross the start line and complete a gybe/tack to clear the penalty. The rule instructs you to sail clear and complete the penalty. 

It depends.  How far did they sail between completing their gybe and starting their tack? If they traveled more than a boat length they are making two separate actions instead of a turn that includes a tack and a gybe in the same direction-going straight between the gybe and a tack to cross the line does not qualify as exoneration. 

Suppose the starting signal occurs at position 2.  I think this is a valid penalty turn.

As is this as they are immediately getting clear of the other boats before taking their penalty:

Getting "well clear" of other competitors could justify a significant trip along the starting line, depending on how many seconds are left before the gun, especially if there were ROW boats to leeward or on starboard in the 2nd row clear astern ... the area just outside the pin could justly be the most reliable and closest "well clear" area available. 

Paul Murray, help me find where the "more than a boat length" part comes from?
Does that apply in super light winds where some speed may be needed to complete the following tack?

Equally valid within the starting line (ignoring the pin) assuming a start under P flag.

I probably should not have included an exact distance travelled in a straight line, but in my defense in wrote the comment early in the morning before coffee. My thought process was what question would I ask if I was on the jury, which would have been “how far did you travel between ending your gybe and starting your tack”  

As the rule says a turn should include one tack and one gybe. If there is any pause , like going straight between the gybe and their tack would not constitute a turn. Case 108 would apply if she did make any pause in her turn to cross the line, which would be advantageous to them. 

Hmm. I've sailed craft where it really isn't practical to make a single continuous turn: you have to steady the boat and prepare for a tack or gybe. In most situations this involves sailing in the wrong direction whilst setting up the next manouver, and thus a turn is a far greater penalty than for something like a Laser that can simply be slammed around. If you're going to state that doesn't constitute a proper penalty then it makes things damn near impossible for certain high performance craft, because the same logic would presumably have a capsize mid turn also invalidate the penalty.

Indeed. On a catamaran, you need to build a bit of speed after the gybe in order to tack.  Otherwise, you just stop, go into irons and possibly back down onto the same tack you started from.

Nothing in "promptly" (44.2) requires a consistent radius.

I'm sure 'promptly ' refers to the time taken to commence the penalty, not doing it. 

Matt, Phil, and Ian:
Do you think either A or B below would be acceptable in satisfying 44.2?  If so what is the test? 

The wording in RRS 44.1 is 'by promptly making the required number of turns in the same direction'.
'Promptly' means 'quickly, without delay'.
In RRS there is a time scale expressed as  'immediately', 'as soon as possible', 'promptly', 'at the first reasonable opportunity'
'Making' means, in this context, 'carrying out an action'
 Which means that a boat must start to and then make her turns 'quickly or without delay'.

While taking her turns, a boat is obliged not to touch a mark (RRS 31) and keep clear of any boat that is not taking a penalty (RRS 21.1.

RYA Case 2015/1 is persuasive if ' a boat commences her penalty turn from a position where the predictable course of other boats means that she would have to interrupt the turn, then she has failed to sail well clear as required by the rule'. Which implies that if another boat sails an unpredictable course then the boat may interrupt her penalty to comply with RRS 21.1.
'Promptly'  allows time to carry out the manoeuvre quickly, without delay. That might include time to gather sufficient speed to carry out the next part of the manoeuvre.

In Paul's example, Yellow reaches a close-hauled course in a position in which she can tack and avoid the mark. One might allow, depending on the boat and the conditions, a short delay to accelerate out of the gybe. In most cases, there would need to be a good reason for the course steered by Yellow A, while, in almost all cases Yellow B's course is not making  her turns 'promptly'.