is this manhood small

Hi Bob,

No, it is not small, it's "average."  For a 15 year old 4-5" is average.  

Remember, it can grow into your early 20's.  Don't compare yourself to others either.  There is a big variation in penis size during the early part of puberty.  For an adult the average is about 5 - 5 1/2".

Hope it helps.