1/5 scale Bristol Centaurus

Discussion in 'A Work In Progress' started by EthanHopper, Mar 20, 2017.

Help Support HMEM by donating:

  1. Jun 13, 2019 #21

    Ivan Winters

    Ivan Winters

    Ivan Winters

    New Member

    Joined:
    May 9, 2019
    Messages:
    3
    Likes Received:
    0
    Gender:
    Male
    Location:
    Bradford, West Yorks UK
    If you are actually planning to fire up this engine then I would be worried about your previous comments re cutting cooling fins with a very fine passage between them (your post of Mar 23 2017 refers to this - to remind you over two years later !). With a small passageway between the fins airflow will be restricted and hence heat dissipation. Heat dissipation is important because the piston and cylinder bores must heat at a similar rate. Otherwise if the piston heats a lot faster than the bore it will jam on the inside of the bore. If the bore heats a lot faster than the piston then the sealing around the sleeve valve as the piston moves up and down will be lost !!
     
  2. Jun 14, 2019 #22

    JimDobson

    JimDobson

    JimDobson

    Well-Known Member

    Joined:
    Sep 11, 2013
    Messages:
    78
    Likes Received:
    35
    Location:
    South Coast of New South Wales Australia
    What a great thread.
     
  3. Jun 14, 2019 #23

    Motorman1946

    Motorman1946

    Motorman1946

    Active Member

    Joined:
    Mar 13, 2014
    Messages:
    25
    Likes Received:
    5
    Occupation:
    Retired Marine Enginer
    Location:
    Somerset, England
    I'm going to be following this thread along because partly it's an interesting engine being a radial sleeve valve engine, partly because undoubtably I will learn a lot (already found how to make spark plugs!) and partly because it's really quite an ambitious project build, so there will be some interesting techniques to witness and admire! So I wish you the best of success and very much hope it comes to fruition and runs well.

    Now, I know this maybe will seem like teaching granny to suck eggs, but beware of excessive clearances especially sleeve to liner. I have built a small bore (0.7875") single cylinder sleeve valve engine which hasn't run yet. Part of the problem is acute lack of compression. The cylinder has an aluminium barrel, with a cast iron liner, a hard steel sleeve and an aluminium piston with cast iron rings, and a junk head with a 'piston' ring type seal. The head seals to the liner top well.no leaks. The liner is a tight sliding fit in the barrel. The sleeve bore was honed so as the piston was a fairly neat sliding fit too, plus the piston has two rings to correct clearances. But I neglected the sleeve to liner clearance. Must have got sloppy in the measuring or just had a senior moment. Or both probably. Measured them after getting no compression and found sleeve to liner had a clearance of about 0.005", not much but enough to loose all compression straight back out the ports. Currently remaking a liner which will be a lapped fit with the sleeve - I hope that will do the trick!

    Chris
     
  4. Jun 14, 2019 #24

    ragnarok

    ragnarok

    ragnarok

    New Member

    Joined:
    Aug 22, 2014
    Messages:
    1
    Likes Received:
    0
    What an amazing first project. I will be watching this.

    Here is a thread of another 18 cylinder radial build, by mayhugh1. It's a very different model of engine, but mayhugh1's posts are long and detailed, with many explanations of his thought processes, techniques, and results, and many pictures. So maybe it can help(if you have time to sift through over 400 posts).

    https://www.homemodelenginemachinist.com/threads/another-radial-this-time-18-cylinders.21601/
     

Share This Page