The first flight lasted only 12 seconds,a flight very modest

The first flight lasted only 12 seconds,a flight very modest...这句话中a flight very modest什么成
The first flight lasted only 12 seconds,a flight very modest compared with that of birds,but it was nevertheless the first time in the history of the world...
这句话中a flight very modest部分的a flight是什么成分?
同位语?还是什么别的?
very modest 又是什么成分?定语从句省略关系词了?还是什么别的?