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  1. #1

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    Club 40 Skyraider II Thrust Angles & CG......>>>

    Anyone care to offer a little help on which direction to go? Should I 0*/0* the engine or add some right thrust?
    Also, CG? I am just behind the spec. Good or bad to be rearward?

  2. #2

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    RE: Club 40 Skyraider II Thrust Angles & CG......>>>

    I have zeroed the engine and it made no appreciable difference in the flight characteristics.  I did this on at least four of the SRMII's.  Start with your CG on the factory point or a little forward.  If you move it aft it gets squirrely fairly quick.  The main thing is make sure the wing is straight to the fuselage and the tail feathers are set up to the wing and that the horiz. stab and the wing are in parallel planes.  After it is together get a lot of airtime turning left at speed.  If you do not have pylons build a set.  The plans are on RCPRO.  Then practice.  You know the drill.  Practice, Practice, Practice, Practice, Practice, Practice, Practice, Practice.  Oh yes,  Practice and have some helpers on the pylons to tell you if you are going to far or cutting.  If you are running a new motor.  Run 3-4 tanks though it on a test stand and stay rich about 1000-1500 of peak.  The run about 6 tanks though it in the air making sure you are 800-1000 off peak and then start leaning it out 100 rpm at a time.  When you are broken in you should have a needle setting 300 rpm off peak using the pinch the fuel tubing method and you should really be stylin.
    Barry...
    http://www.RCPRO.org

  3. #3

    Join Date
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    RE: Club 40 Skyraider II Thrust Angles & CG......>>>

    G.S.G. Most of my SR MkII end up with a little right thrust, but not everyone. I use right thrust to reduce, or eliminate a "hook" in a left pylon (usually full up elevator) turn. The condition I'm describing can also be caused by a heavy left wing, or excessive aileron hinge gap. There are some other causes, such as missaligned tail surfaces, but we won't go into those right now. On your first test flights try full up elevator turns to both the right and to the left. All things being equal, the most common reaction is for your airplane to "hook" or "tuck" to the left, because as it decelerates in the turn, torque will make it roll left, but not all airplanes react the same. If you are really lucky your airplane will pull true in both directions. Usually if they "tuck" in a left turn, they will climb in a right turn. Sometimes, for no explainable reason, you will get an airplane that "hooks" to the right, and climbs to the left. If my airplane responds this way, I don't shim in right thrust. For thrust shims I laminate multiple layers of fiberglass cloth between two pieces of plate glass. I use approximately 4 oz. per sq. yd. cloth. The first two layers are slightely larger than the back of my motor mount, about 1/2 in on each side. Then the next 6 or 7 layers of cloth each get smaller by a 1/4 in. and are arranged so one edge of the sandwich is only 2 layers thick, and the other edge is 8 or 9 layers thick. The whole sandwich is clamped between the two pieces of plate glass, so you end up with a "wedge". I use PVA (poly vinyl alcohol) as a release agent. After the wedge cures I cut out a circle the size of my motor mount. My thrust shims are probably over kill! Another test to perform, before putting in any rudder trim, is to fly your airplane directly over your head. When it is going away from you observe if the nose is hanging to the right or the left. If you are lucky it will be tracking straight, but frequently the nose will be "hanging" to the left. Try shimming in right thrust to get it to fly straight, instead of using right rudder. I probably "over trim" my airplanes, but I like to have them flying at their best when I crash them. Now everyone knows my trim secrets. Greg

  4. #4

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    RE: Club 40 Skyraider II Thrust Angles & CG......>>>

    Hey thanks guys.

    Great info. I currently have both my ships with 1.5* right & 0* up/down thrust. I build them this way out of habit.

    Thanks to everyone who has helped me get these together. I really appreciate it.


    The white airplane is my primary ship, built as light as possible.


    The Yellow bird is my practice ship with heavier servos, larger battery, etc...



  5. #5

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    RE: Club 40 Skyraider II Thrust Angles & CG......>>>

    You do know that the white covering is heavier than all the other colors because of the amount of pigment in it as much as 1 oz. more.

    Now, did that make your day???  My first SRMII was white and it flew great and was fast so, no big deal.
    Barry...
    http://www.RCPRO.org

  6. #6

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    RE: Club 40 Skyraider II Thrust Angles & CG......>>>

    No heavy white on my new one...maybe a little now that I look at it again. Shoot!!!
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  7. #7

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    RE: Club 40 Skyraider II Thrust Angles & CG......>>>

    ORIGINAL: GREG DOE

    G.S.G. Most of my SR MkII end up with a little right thrust, but not everyone. I use right thrust to reduce, or eliminate a ''hook'' in a left pylon (usually full up elevator) turn. The condition I'm describing can also be caused by a heavy left wing, or excessive aileron hinge gap. There are some other causes, such as missaligned tail surfaces, but we won't go into those right now. On your first test flights try full up elevator turns to both the right and to the left. All things being equal, the most common reaction is for your airplane to ''hook'' or ''tuck'' to the left, because as it decelerates in the turn, torque will make it roll left, but not all airplanes react the same. If you are really lucky your airplane will pull true in both directions. Usually if they ''tuck'' in a left turn, they will climb in a right turn. Sometimes, for no explainable reason, you will get an airplane that ''hooks'' to the right, and climbs to the left. If my airplane responds this way, I don't shim in right thrust. For thrust shims I laminate multiple layers of fiberglass cloth between two pieces of plate glass. I use approximately 4 oz. per sq. yd. cloth. The first two layers are slightely larger than the back of my motor mount, about 1/2 in on each side. Then the next 6 or 7 layers of cloth each get smaller by a 1/4 in. and are arranged so one edge of the sandwich is only 2 layers thick, and the other edge is 8 or 9 layers thick. The whole sandwich is clamped between the two pieces of plate glass, so you end up with a ''wedge''. I use PVA (poly vinyl alcohol) as a release agent. After the wedge cures I cut out a circle the size of my motor mount. My thrust shims are probably over kill! Another test to perform, before putting in any rudder trim, is to fly your airplane directly over your head. When it is going away from you observe if the nose is hanging to the right or the left. If you are lucky it will be tracking straight, but frequently the nose will be ''hanging'' to the left. Try shimming in right thrust to get it to fly straight, instead of using right rudder. I probably ''over trim'' my airplanes, but I like to have them flying at their best when I crash them. Now everyone knows my trim secrets. Greg
    Greg, that is one of the better guide lines to fallow when trimming out your SR MKII or LA Racer I will spend hours on end working on balance and trim to get it just the way it feels the best when I think it’s ready for racing! But I can so relate to how you described β€œI like to have them flying at their best when I crash them” LOL I can so relate to that quote! That is a great analysis!

    Gary
    Fish

  8. #8

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    RE: Club 40 Skyraider II Thrust Angles & CG......>>>

    I need help on determining the angle of the 1.5 degree offset. how many washers or how thick is what ever shim was used on the beam mount to get this angle?

  9. #9

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    RE: Club 40 Skyraider II Thrust Angles & CG......>>>


    ORIGINAL: Bozarth

    No heavy white on my new one...maybe a little now that I look at it again. Shoot!!!
    That is one good looking graphic job! Did you hand cut the graphics out for your Sky Raider?

    Gary
    Fish

  10. #10

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    RE: Club 40 Skyraider II Thrust Angles & CG......>>>

    Thank you Gary. It is all Monokote that I hand cut.

  11. #11
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    RE: Club 40 Skyraider II Thrust Angles & CG......>>>

    That plane is too pretty to crash[]
    throttling back during a crash means you are a "quitter "
    "cutting suks"
    "everyone is crazy, some are just more obvious than others"

  12. #12

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    RE: Club 40 Skyraider II Thrust Angles & CG......>>>

    Here are backups #1 and #2:
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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ID:	1818190   Click image for larger version. 

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ID:	1818191  

  13. #13

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    RE: Club 40 Skyraider II Thrust Angles & CG......>>>

    ORIGINAL: kydave

    I need help on determining the angle of the 1.5 degree offset. how many washers or how thick is what ever shim was used on the beam mount to get this angle?

    If the engine mount is 2.5" wide, and you rotate it 1.5 degrees, the gap would be 0.0654 inches. 1/16" = 0.0625 inches.

    Kurt

  14. #14

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    RE: Club 40 Skyraider II Thrust Angles & CG......>>>

    Thanks
    I have some 1/16 alum strip I got at Lowes and I cut a slit in a section to slid in between the mount and firewall
    . I went out and took some laps and it didn't tuck left in the turn. GREAT!!!!


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