Rereading juvenile series. I own the odd couple but considering the high level of weeding I'm finding, I feel lucky to get any from libraries! Damon Knight edited an anthology series called Orbit and the Adelaide Lending Library held a run of first edition hardcovers, now not a single volume is known to be held in South Australia. Any further information is welcome.

First Hugh Walters. This site provides quite an overview.
http://www.sandbourne.eclipse.co.uk/walters/index.html

I've found the greatest holdings are not in the UK where he was based, or in Australia where much of the stories were set but Canada.

His main series (Chris Godfrey AKA UNEXA) featured teenage astronauts exploring the solar system (from Woomera), I have never even seen a copy of his other works. They used to be ubiquitous in school libraries. SLSA is the State Library of South Australia, UniSA is the University of South Australia (whose former Colleges of Advanced Education teacher resource collections are a great resource for me), others are grouped by state and source is the National Library's Trove search, which depends on member library claims and is thus not definitive. Question marks (?) indicate conflict between sources.

1. Blast Off at Woomera (1957) SLSA ACT VIC QLD WA NSW
2. The Domes of Pico (1958)
3. Operation Columbus (1959) VIC
4. Moon Base One (1960) VIC
5. Expedition Venus (1962)  NSW QLD
6. Destination Mars (1963) UniSA ACT NSW
7. Terror by Satellite (1964) NSW
8. Journey to Jupiter (1965) NSW ACT
9. Mission to Mercury (1965)
10. Spaceship to Saturn (1967) VIC
11. The Mohole Mystery (1968)
12. Nearly Neptune (1968) UniSA NSW ACT VIC
13. First Contact? (1971) UniSA
14. Passage to Pluto (1973) UniSA NSW
15. Tony Hale, Space Detective (1973) UniSA NSW VIC
16. Murder on Mars (1975) QLD VIC
17. The Caves of Drach (1977) QLD VIC
18. The Last Disaster (1978) ACT NSW QLD
19. The Blue Aura (1979) ACT QLD VIC
20. The Dark Triangle (1979) ACT NSW VIC
21. The Glass Men (unpublished)

Boy Astronaut series:

1. Boy Astronaut (1977) ACT QLD NSW? VIC?
2. First Family on the Moon (1979) ACT QLD WA
3. School on the Moon (1981) (ISBN 0200727435) ACT NSW QLD VIC

Other Books:

1. P-K (Psychokinesis) (1986) South Australian Public Library Network? NSW

Next, Ivan Southall's Simon Black. The ex-RAF title character built a vertical take off jet (with "rotors in the wings"), then variant craft including spaceships and orbital nuclear bombers.

An overview.
http://www.collectingbooksandmagazines.com/ivansouthall.html

Unfortunately the uniform brown covered 1970s Angus and Robertson reprints I initially read (and are still common) were highly edited, presumably to update temporal references, with as much as a quarter of the material excised. I am concentrating on SA holdings only here, asterisk (*) indicates where original or unedited edition is known to be held.

Meet Simon Black (1950) UniSA*
Simon Black in Peril (1951) SLSA Flinders
Simon Black in Space (1952) SLSA Flinders
Simon Black in Coastal Command (1953) UniSA*
Simon Black in China (1954) SLSA Barr-Smith
Simon Black and the Spacemen AKA Simon Black on Venus (1955) SLSA Flinders
Simon Black in the Antarctic (1956) SLSA
Simon Black Takes Over (1959) UniSA
Simon Black at Sea (1961) UniSA

Finally the Heinlein Juveniles; twelve books for younger readers Robert A Heinlein wrote from 1947 until he got carried away with Starship Troopers and ended up with a militarist libertarian polemic. These should be common as, but there are some omissions. SAPL is South Australian Public Libraries, again I will restrict the holdings to this state.
http://en.wikipedia.org/wiki/Heinlein_juveniles

Rocket Ship Galileo (1947)
Space Cadet (1948) Barr-Smith
Red Planet (1949) SAPL
Farmer in the Sky (1950) UniSA
Between Planets (1951) SAPL
The Rolling Stones aka Space Family Stone (1952) TAFE SA
Starman Jones (1953) SAPL
The Star Beast (1954) Flinders
Tunnel in the Sky (1955) SAPL?
Time for the Stars (1956) Gawler
Citizen of the Galaxy (1957) UniSA
Have Space Suit—Will Travel (1958) Barr-Smith