derekf,
Never give up. No matter what path you chose there will be challenges. Don't turn away from the challenege just because it is so... try to convince yourself there is something to learn. I too used to get frustrated with certain rejections. I still do but not as often. I have learned a tremendous amount by being rejected over and over again. It does give you a better appreciation for what THIS SITE is looking for. It is NOT what is accepted to be the BEST way to edit or present a photo. It is simply the choice A.net has made.
From time to time, a rejection will seem unwarranted. Appeal it. You may find that if it wasn't outside the boundaries, the head screeners will accept it. Mistakes do happen.
I will only comment on your A350 shot. The aircraft is soft unfortunately. It is also low in frame to my taste and perhaps the screeners as well (although not mentioned. The crop motive is also questionable. I would have either gone much tighter or pulled back to show more of the plane.
Try a
USM pass at 400 0.2 in Photoshop and see how the titles improve.
Lastly the heat distortion is clearly visible in the top of the fuselage.
I hope you will choose to stay and continue to perfect your craft to the A.net standards of posting. A lot of gems are uploaded everyday by all photographers amateur or professional.
Cheers!