Register

If this is your first visit, please click the Sign Up now button to begin the process of creating your account so you can begin posting on our forums! The Sign Up process will only take up about a minute of two of your time.

Results 1 to 14 of 14

  1. #1

    Join Date
    Nov 2004
    Location
    Blackpool, UNITED KINGDOM
    Posts
    286
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    Can I temporarily use a 11 x 7 prom on my Magnum GP 40?

    Can I temporarily use a 11 x 7 prom on my Magnum GP 40?

    I've only got one propellor left until my new 10 x 6 ones arrive.

    How will I fair if I use a Graupner 11 x 7 instead for a while?

    will it screw my engine or anything?

  2. #2
    Hossfly's Avatar
    Join Date
    Dec 2001
    Location
    New Caney, TX
    Posts
    5,843
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Can I temporarily use a 11 x 7 prom on my Magnum GP 40?

    Cut tips 3/8 to 1/2" each and balance. You can also sand a very small amount off the back trailing edge for 1-2 inches from tips. This will provide
    a washout for the tips which is always good for picking those lost RPMs that your uncut portions drag down.
    A .40 will turn a 11-7. Way back in time, 10-6 was standard for .29-35 and 11-5 to 11-7 was standard for .40.
    If your magnum .40 is rather new, I suggest cutting the tips for a couple hours running time. Then back to your standard.

    Example of prop stuff. We used to have races with a standard sport model, .40 sized Super Tigre, 9-7 prop. That model was a bear to land with the 9-7.
    For fun place a standard 10-6 on it and it was better. For real flying and fun place a 11-4 on it and it was MUCH better to land, a bit slower, but aerobatics were

    (IMO) 10 times better.
    Horrace Cain AMA L-93

    “Peace is the brief glorious moment in history when everyone stands around reloading.\" T. Jefferson

  3. #3
    JohnBuckner's Avatar
    Join Date
    Dec 2001
    Location
    Kingman, AZ
    Posts
    9,058
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Can I temporarily use a 11 x 7 prom on my Magnum GP 40?


    Carl an 11/7 is to much load for those GP magnum forties. You will run the risk of constant overheating and the resulting deadsticks.

    All is not lost as Hoss suggested you certainly can cut it down and I would not get fancy about it and just use a straght cut. Here in the first photos is the best procedure for cutting down a prop to assure both blades have the same length. For that small venturi engine I woud cut it down to a 9.5 /7 and do not try to change the blade planform or pitch. Of course do balance agine after cutting or reshaping.

    The last photo is a typical modelers supply of props. Nope ya never can have enough.


    John
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Fd91907.jpg 
Views:	10 
Size:	36.5 KB 
ID:	1903819   Click image for larger version. 

Name:	Bw72093.jpg 
Views:	11 
Size:	38.7 KB 
ID:	1903820   Click image for larger version. 

Name:	Pu50047.jpg 
Views:	18 
Size:	92.1 KB 
ID:	1903821  
    \"Keep your controllines tight\"

  4. #4

    Join Date
    Feb 2005
    Location
    Zephyrhills, FL
    Posts
    1,917
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Can I temporarily use a 11 x 7 prom on my Magnum GP 40?

    I want the messed up one in the lower left center . lol ENJOY !!! RED

  5. #5
    Moderator CGRetired's Avatar
    Join Date
    Sep 2004
    Location
    Galloway, NJ
    Posts
    8,999
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Can I temporarily use a 11 x 7 prom on my Magnum GP 40?

    Jeez, John.. got enough props there?

    I have about 50 or so and I thought that was a lot.

    CGr
    Skylark 70 - OS .75 AX; Excelleron 90 - OS 1.20 AX; Venus II - OS 1.20 AX; And, I still fly my trainer, Hanger 9 Alpha - OS .46 FX! Some electrics. Airtronics RD8000 - Spektrum DX7 - DX6i. AMA 705964.
    Semper Paratus!

  6. #6
    JohnBuckner's Avatar
    Join Date
    Dec 2001
    Location
    Kingman, AZ
    Posts
    9,058
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Can I temporarily use a 11 x 7 prom on my Magnum GP 40?

    Well Heck CG a mans got to have his props 'eh. Oh OK you can have the messed up one in the lower left center RED besides I ain,t messed with single bladers in a long time
    \"Keep your controllines tight\"

  7. #7

    Join Date
    Dec 2006
    Location
    Fort Worth, TX
    Posts
    4,573
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Can I temporarily use a 11 x 7 prom on my Magnum GP 40?

    How long are you actually going to have to wait for the 10x6's to get there? The plane will fly differently with the 11x7, and not in a good way. The engine will lug and not get into the RPM where it makes decent horsepower. I'll say stick with the combination that's been working for you and be patient until your props come in.
    No kid, I said break ground and fly into the wind!

  8. #8

    Join Date
    Nov 2004
    Location
    Blackpool, UNITED KINGDOM
    Posts
    286
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Can I temporarily use a 11 x 7 prom on my Magnum GP 40?


    ORIGINAL: jester_s1

    How long are you actually going to have to wait for the 10x6's to get there? The plane will fly differently with the 11x7, and not in a good way. The engine will lug and not get into the RPM where it makes decent horsepower. I'll say stick with the combination that's been working for you and be patient until your props come in.

    I think this may be my best bet.

    As it happens thought the 11 x 7 was fitted to an irvine 40 or 42 (can't remember number) when I bought a Ripmax trainer ready built. Perhaps someone was uneducated about the correct choice of prop I guess.

  9. #9

    Join Date
    Nov 2004
    Location
    Blackpool, UNITED KINGDOM
    Posts
    286
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Can I temporarily use a 11 x 7 prom on my Magnum GP 40?

    Post came and no prop.

    Called the model shop to be told it only got posted yesterday after me ordering it Monday. What a joke. I'll just order online next time.

    The other prop WILL be getting cut down if the others don't arrive tomorrow. I can;t go all weekend without flying.

  10. #10
    JohnBuckner's Avatar
    Join Date
    Dec 2001
    Location
    Kingman, AZ
    Posts
    9,058
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Can I temporarily use a 11 x 7 prom on my Magnum GP 40?

    An 11x7 is also too much for either an Irvine 40 or 42 as well as the Magnum GP 40 and yes was an inappropriate prop to start with..

    Agine if cutting down 9.5 x 7 would be appropriate for the GP 40 and only reducing diameter with no attempt to change blade planform or pitch. These involve additional skills and techniques and beyond the scope of what you want to do.

    John
    \"Keep your controllines tight\"

  11. #11

    Join Date
    Nov 2004
    Location
    Blackpool, UNITED KINGDOM
    Posts
    286
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Can I temporarily use a 11 x 7 prom on my Magnum GP 40?

    Thanks john. I'll havea go at cutting it down since I'm itching to get out tonight. Never mind tomorrow.

    Perhaps I can whittle one out of some wood? I have a big pile of willow waiting to be mulched in the garden. [:-]

  12. #12
    JohnBuckner's Avatar
    Join Date
    Dec 2001
    Location
    Kingman, AZ
    Posts
    9,058
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Can I temporarily use a 11 x 7 prom on my Magnum GP 40?


    ORIGINAL: carl24bpool

    Perhaps I can whittle one out of some wood?

    And this is the way its done. A rather lengthy and time consuming process that has its rewards but I would not recomend this for you. You are in to big a hurry. Cutting down a prop though is a time honored technique that is relitively simple.

    Reread Jesters last post in your other thread as he has intimated many gems there that you need to carefully consider.

    John
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Vt57566.jpg 
Views:	13 
Size:	37.9 KB 
ID:	1904027   Click image for larger version. 

Name:	Wr54578.jpg 
Views:	9 
Size:	32.3 KB 
ID:	1904028   Click image for larger version. 

Name:	Di10361.jpg 
Views:	13 
Size:	33.6 KB 
ID:	1904029  
    \"Keep your controllines tight\"

  13. #13

    Join Date
    Nov 2004
    Location
    Blackpool, UNITED KINGDOM
    Posts
    286
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Can I temporarily use a 11 x 7 prom on my Magnum GP 40?

    Thats some very nice handywork there.

    What sort of wood do you use? are they maple?

  14. #14
    JohnBuckner's Avatar
    Join Date
    Dec 2001
    Location
    Kingman, AZ
    Posts
    9,058
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Can I temporarily use a 11 x 7 prom on my Magnum GP 40?

    That I believe is just a straight grain fir.

    John
    \"Keep your controllines tight\"


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
All times are GMT -6. The time now is 11:40 PM.

SEO by vBSEO 3.6.1 ©2011, Crawlability, Inc.