The compound noun 'aircraft' (no space) is the same for both the singular and the plural form.
Examples:
An aircraft landed on the runway. (singular)
Several aircraft circled the field waiting to land. (plural)
The plural possessive is airplanes'.
Aircraft is already plural. "There are many aircraft in that hangar." The word may also be used in the singular, e.g. "That engine in that aircraft doesn't sound quite right."
The plural of aeroplane is areoplanes.
You seem to be having trouble with compound words. Which thing are there more of - airs or crafts? You don't have airs craft because there aren't two airs. There are two air crafts.
One aircraft, two aircraft, ten aircraft.
The plural of plane is planes
Aeroplanes.
Aircraft
Bridges is the plural form of bridge.
"Beliefs" does not have a plural form, as it is already plural. Beliefs is the plural form of belief.
There is no plural form for the word, countries. This word itself is a plural.
The plural of "she" is "they", so the plural of "she had" is "they had".
There is no plural form of pupae. Pupae is the plural form of pupa.
The plural of aircraft is aircraft.One aircraft, two aircraft, ten aircraft.
Both the singular and the plural is aircraft.The plural possessive form is aircraft's.Example: All of the aircraft's inspections have been completed.
The noun 'aircraft' is an uncountable noun. The singular and the plural possessive form is aircraft's.EXAMPLESOne aircraft's owner has not paid the airport fee. (singular)All of these aircraft's owners are delinquent in their fees. (plural)
The plural of aircraft is aircraft. Much like how the plural of deer is deer. (Singular: That is such a beautiful aircraft / Plural: Look at all of those aircraft)
Aircraft is both singular and plural e.g. the pilot boarded his aircraft and took off; we watched as aircraft of all shapes and sizes filled the sky.
Bridges is the plural form of bridge.
"Beliefs" does not have a plural form, as it is already plural. Beliefs is the plural form of belief.
There is no plural form for the word, countries. This word itself is a plural.
"Groceries" is the plural form of "grocery."
The plural form of "meter" is "meters."
The singular possessive form is aircraft's.
The plural form for the noun sergeant is sergeants; the plural possessive form is sergeants'.