Finished the F-20 (pics inside!)
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Finished the F-20 (pics inside!)
Well I finally finished my Sportsman Aviation F-20, and boy is she a beauty! I havent' flown her yet, I still need to get the CG correct. Thanks for any help a lot of you gave me about spinners and mufflers and stuff.
I'm using a Thunder Tiger pro .46 with a JETT pipe turning a Tru-Turn. I'm a little nervous about it first flight, probably this next weekend.
I'm using a Thunder Tiger pro .46 with a JETT pipe turning a Tru-Turn. I'm a little nervous about it first flight, probably this next weekend.
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RE: Finished the F-20 (pics inside!)
Thanks for all the approvals! First flight report will come some....I've never balanced a plane laterally? Is one side heavier than the other?
If so, how do you balance it laterally the correct way and why would it dip to the right at full throttle take off?
Oh, and it is stock ARF covering. I just painted the canopy and cowling.
If so, how do you balance it laterally the correct way and why would it dip to the right at full throttle take off?
Oh, and it is stock ARF covering. I just painted the canopy and cowling.
#8
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RE: Finished the F-20 (pics inside!)
I have used a great way of balanceing a plane latterally . Your plane is totally finished so a screw with hook eye is out of the question (thats that typical way placed at the CG)and simply hang it from a string .
YOU can simply take two dowelsl , put pencil erasers on them to protect your plane , get a small piece of scrap wood 14"by 14" should be ok . Drill two holes in the wood 12" or more apart in a straight line .Draw a straight line from end to end on the wood where you intend to put the dowels and it should be centered to the base (example 14" base divide in two and 7" is the center . Drill two holes Glue the dowels in the base like two post , put the erasers on the tops of the dowels . Place a simple shirt button on the wood base inbetween the two dowels where your normal (front to back CG would be when your plane is sitting on these dowels) . Now place your plane on the dowels -make sure it centered to the line you have drawn on the wood base . YOU will see your plane tip left /right or balance just right .
If its tips , you can try to center your battery to make it balance but remember dont go out of the normal CG while trying to balance latterally .
YOU can simply take two dowelsl , put pencil erasers on them to protect your plane , get a small piece of scrap wood 14"by 14" should be ok . Drill two holes in the wood 12" or more apart in a straight line .Draw a straight line from end to end on the wood where you intend to put the dowels and it should be centered to the base (example 14" base divide in two and 7" is the center . Drill two holes Glue the dowels in the base like two post , put the erasers on the tops of the dowels . Place a simple shirt button on the wood base inbetween the two dowels where your normal (front to back CG would be when your plane is sitting on these dowels) . Now place your plane on the dowels -make sure it centered to the line you have drawn on the wood base . YOU will see your plane tip left /right or balance just right .
If its tips , you can try to center your battery to make it balance but remember dont go out of the normal CG while trying to balance latterally .
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RE: Finished the F-20 (pics inside!)
I've never had to laterally balance any other planes and they flew fine...so why would this type of model be so unbalanced? And if it is a little off on one side or another, why would it dip to the right after take off?
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RE: Finished the F-20 (pics inside!)
The F-20 has a low-aspect ratio wing (short span). The engine cylinder and muffler are hanging on the right side of the plane, with that weight pretty much acting about the roll axis of the airplane.
On most sport planes, that weight inbalance would be fairly easily distributed in roll stability on a longer wing. The short wings do not distribute that extra weight offset quite as well - less moment arm to counter-act the weight with lift. Plus, the wing 'lift' can not correct the weight imbalance until the wing itself is up to speed and flying. So if you get into a situation where the plane leaves the ground at a minimum airspeed, that weight will roll the plane to the right. Once it the air and flying, yes the plane can be trimmed to deal with the weight offset, but its that low/slow situation where the lateral balance will get ya.
Chances are a small piece of stick-on weight strip (1/4 oz or so) on the left wingtip is all that will be needed.
On some of the racing planes, you will occationally see where some of us have taped quarters (25c) on the left wing for trip purposes. This is in part for the same reason. (quarters are flat and easy to tape on for trim flights - permanent weight is usually added afterward if practicle)
On most sport planes, that weight inbalance would be fairly easily distributed in roll stability on a longer wing. The short wings do not distribute that extra weight offset quite as well - less moment arm to counter-act the weight with lift. Plus, the wing 'lift' can not correct the weight imbalance until the wing itself is up to speed and flying. So if you get into a situation where the plane leaves the ground at a minimum airspeed, that weight will roll the plane to the right. Once it the air and flying, yes the plane can be trimmed to deal with the weight offset, but its that low/slow situation where the lateral balance will get ya.
Chances are a small piece of stick-on weight strip (1/4 oz or so) on the left wingtip is all that will be needed.
On some of the racing planes, you will occationally see where some of us have taped quarters (25c) on the left wing for trip purposes. This is in part for the same reason. (quarters are flat and easy to tape on for trim flights - permanent weight is usually added afterward if practicle)
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RE: Finished the F-20 (pics inside!)
ORIGINAL: setxws6
I've never had to laterally balance any other planes and they flew fine...
I've never had to laterally balance any other planes and they flew fine...
#13
RE: Finished the F-20 (pics inside!)
FBD,
Forgive my absence from the fold. However I think I've done pretty good to have moved 700 miles, gotten married, started a new job and still managed to find a place to fly in a matter of 6 months.
It's good to be back into the nitrous burning spirit again (just in time for the holidays ) I recently picked up a DC F-20 and was trying to locate the CG. I have a set of plans but being the skeptic that I am, would like to find out from the experts (and that's where u come in) what CG recommendations you could offer.
I hope to become more active in the universe in the days to come.
Rev on Bro's...................[>:]
Forgive my absence from the fold. However I think I've done pretty good to have moved 700 miles, gotten married, started a new job and still managed to find a place to fly in a matter of 6 months.
It's good to be back into the nitrous burning spirit again (just in time for the holidays ) I recently picked up a DC F-20 and was trying to locate the CG. I have a set of plans but being the skeptic that I am, would like to find out from the experts (and that's where u come in) what CG recommendations you could offer.
I hope to become more active in the universe in the days to come.
Rev on Bro's...................[>:]
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RE: Finished the F-20 (pics inside!)
The instructions that came with mine said the CG should be between 5.5-6.0 inches back from leading edge of the wing next to the body. Mine's still a slightly nose heavy.