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Help with Sig 1/2A Skyray

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Old 04-07-2011, 03:24 AM
  #1
jpuke
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Default Help with Sig 1/2A Skyray

Good morning!

I got myself a 1/2A Sig Skyray that I've put together and I'm in the final stages of getting it ready for its (and my) first flight. My question is regarding how to balance the airplane. I have a Great Planes aircraft balancer but it says it's only for planes that are greater than 2 lbs in weight and I'm pretty sure my Skyray is not and that's why I'm having problems balancing it.

I have gotten it to balance on the aircraft balancer but only but setting about 1 oz of lead on the nose - does this seem excessive? How do you all go about attaching weight to your models to balance them? What could I use to test its balance?

Any other tips on getting this airplane to fly well from the start?

Thanks,
jpuke
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Old 04-07-2011, 07:16 AM
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Jim Thomerson
 
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Default RE: Help with Sig 1/2A Skyray

I don't know what the plans show for CG, but I, as an experienced 1/2A flyer, would not balance it any farther back than 1/2 inch from the leading edge.
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Old 04-07-2011, 08:36 AM
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Default RE: Help with Sig 1/2A Skyray

Jim is 1000% correct. I have a Skyray that I fly all the time. I balance it3/4 inch from the leading edge, but I am an experienced combat and stunt flyer. A little nose heavy won't hurt for your first flights, you can always take some weight off, but a tail heavy plane is a handful. And don't forget tip weight. I use just a nickle, but a little more won't hurt if you are inexperienced.
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Old 04-07-2011, 01:10 PM
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Default RE: Help with Sig 1/2A Skyray

Dont know what you are using for a motor but if it is a Cox with the tank attached the plane balances... and you dont really need to do more than make sure the nose drops when you put two fingers under the wing 3/4" back from the leading edge. CL 1/2A planes tend to fly better with the CG a little further forward than you may expect. The only time I have seen a skyray not balance was when someone locally changed the fuse over to a beam mounted engine resulting in the TD being back about an inch and a half from where it would be if firewall mounted.
Bob
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Old 04-07-2011, 02:53 PM
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jpuke
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Default RE: Help with Sig 1/2A Skyray

Thanks for the help guys. Idid add some weight to the nose, I guess I'll see how it goes. The only difference between what I made and what the kit calls for is that the engine I have is a Babe Bee (?) rather than an engine that has the 8cc tank. Maybe the shorter (5cc) tank alters where it balances. We'll see.

Jeremy
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Old 04-11-2011, 07:20 AM
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Default RE: Help with Sig 1/2A Skyray


Many things ca affect the balance point of these airplanes and they are all variable. 95% of the paint you put on goes behind the CG so if you pile the paint on to make a slick finish it can make the plane tail heavy. Or you could have extra heavy wood in the fuselage and tail surfaces and or a light engine or all of the above. One of the best ways of balancing a tail heavy airplane like this is to make spacers to put between the firewall and engine since the engine is the heaviest thing ahead of the CG. I make these spacers the same shape as the firewall out of 1/4" plywood and epoxy them to the firewall. The spacers and glue add some weight but more importantly the move the mass of the engine forward.

Good luck,

Bob Nelson
Design Engineer/Customer Service
SIG MFG. CO.
Montezuma, Iowa
bobnelson@sigmfg.com

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Old 04-12-2011, 03:26 AM
  #7
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Default RE: Help with Sig 1/2A Skyray

I went out to fly the airplane 3 times over the last four days and finally got some good flights in yesterday.

The first night I went out and promptly crashed and had to take it home to mend the fuselage.

I went out the next day and got in a good flight of about 6 laps before crashing and then on the next run my pit man (25 yr. old "little brother") got his finger mixed up with the propeller while adjusting the needle valve so we had to cut it short and head off to the ER for stitches.

I was out again yesterday and managed to run a tank dry without crashing and found the plane to be responsive and fun to fly, though I'm still getting used to the dizziness.

Here's a few things I've learned: (I'm sure you have all figured these out already)
1) I should have started with a genuine 1/2A handle. My first flight was with a Sullivan adjustable handle and I think it had far too much movement for a beginner. I switched to a smaller handle that Ifound in an old Guillow's kit and that seems to be better.

2) I didn't need the nose weight. After crashing twice yesterday the nose weights fell off and then I managed to get in better runs. The roller coaster effect went away - I didnt' have to keep pulling up to avoid crashes and was able to fly it reasonably level.

3) The plane tends to dive when I'm flying into the upwind side of the circle. Itook off downwind but found myself having to pull up from a dive almost every time I came around to the side where the wind was blowing. Do larger planes have this trouble? Should Ibe worried that there won't be many good days to fly here in Nebraska if the wind is genuine problem?

I flew with the prop on backwards and it was plenty fast. Not sure I can keep my head from spinning too much if Iturn the prop around and let the plane go full speed.
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Old 04-13-2011, 06:17 AM
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Default RE: Help with Sig 1/2A Skyray

jpuke,

You are correct about the handle. Your handle spacing should be about the same as your spacing on the bellcrank. One of the nice features about the Skyray is the external controls and the ability to change control movement. I am hoping yours is set-up with minimum movement (beginner setting). That is with the pushrod in the inner hole on the bellcrank and the outer hole on the control horn. This, along with the closer spacing on the handle should allow you smoother control while you are learning to fly and are still getting over the dizziness.

As you gain more experience, you can move the pushrod to the outer hole on the bellcrank and finally to the inner hole on the control horn. All of this assumes that SIG still provides two pushrod holes in the bellcrank and control horn. I have two Skyrays...one is ancient and the other is merely old. [8D]

You asked about balance but just as important is alignment. Make sure your stab and elevator are on perfect alignment with the wings. This includes looking at it from the side, the back, and the top.

Make sure your elevator is in the neutral position with the bellcrank so that you have an equal amount of up and down.

Make sure the rudder is straight with the fuselage or pointing out a little, but not pointing in.

Make sure the engine points out just a little.

If all of these are correct, you should be able to fly on 35' lines without it coming in on you. You may need to turn the prop around to maintain good pull. You probably have checked all of this stuff, but just in case...

Good luck with it.

George
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Old 04-16-2011, 04:31 AM
  #9
jpuke
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Default RE: Help with Sig 1/2A Skyray



gcb - Thanks for the tips on the pushrod locations! The instructions say where to put it on the control horn (bottom hole, the middle hole is for stunting according to SIG) but the instructions also picture the outer hole for the bellcrank, I'll get that moved before Igo to fly again.

What do you do to get the lines tied evenly? I was intrigued by the Sullivan handle because it was adjustable but now with the smaller 1/2A handle I have to tie it perfectly so it'll work well and that took some work.

I think I have the alignment pretty good between the wing, stabilizer and rudder but the wing itself came warped a bit. I'm also thinking about getting a Lil' Wizard from Brodak. I hear these are lousy for stunting but good for learning to go around in a circle.

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Old 04-16-2011, 08:28 AM
  #10
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Default RE: Help with Sig 1/2A Skyray

Quote:
ORIGINAL: jpuke
...What do you do to get the lines tied evenly? I was intrigued by the Sullivan handle because it was adjustable but now with the smaller 1/2A handle I have to tie it perfectly so it'll work well and that took some work.
Most 1/2A handles have two or three sets of holes for spacing and a small knob (or another device) in the middle. Assuming dacron or fishing line, you run the lines (uncut) through the handle and to the plane...I like to use clips on the ends. You wrap the center of the lines over the center device and adjust by moving the loop as needed.

George
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