steve
Flying officer
Posts: 11
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Post by steve on Feb 18, 2009 2:05:04 GMT 1
Hi Everyone, I'm Steve Allen and as the subject line says, I'm new to RC flying but I have been building models ins some form or another since I was 5. That's.....uh......43 years ago. I have flown my Cub a number of times and haven't crashed yet. A few rough landings, nose overs and such but so far so good. I just refinished my Cub and posted some pictures in the painting section. Here is one.  Once the weather clears, I'll see how she flies with the new paint job. I can say it weighs a bit more. I looked on the forum and someone posted that the CG should be between 1.5 and 1.75 of an inch from the LE. I added 2 ounces of weight in the cowl and so far, my CG is around 2 inches back from the LE. We'll see how she flies. Hopefully this weekend. |
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Post by Ellis on Feb 18, 2009 6:09:12 GMT 1
Excellent job Steve! You even cleaned up the push-rod holes - nice!
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Post by gagallagher04401 on Feb 18, 2009 13:24:57 GMT 1
Looks AWESOME! What type of paint did you use?
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Post by ginginho on Feb 18, 2009 17:57:24 GMT 1
Hello Steve and welcome to the forum. That's a lovely paint job you've done there, very tidy looking SC. As for your CoG, I believe it should be more like 2.25 to 2.5 inches from the leading edge. Take a look at supercubclub.proboards78.com/index.cgi?board=sccgeneral&action=display&thread=1843Brian's shows as 2.46 and states that it flys well. I know mine is about 2 +3/16ths of an inch from the leading edge and is, if anything, a little too nose heavy. So, if anything (or unless I've got it totally wrong) the weight you added to the nose has made it more nose heavy and moved your CoG forward, whereas you need to get it back a bit. What's it measure from the LE when you have no additional weight added to the nose? |
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wjcjr1
Flight lieutenant
Posts: 92
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Post by wjcjr1 on Feb 19, 2009 0:03:19 GMT 1
Welcome!
I posted a comment on your plane where it was initially posted but again NICE JOB, very clean I think. I like clean, not flashy and smart detail. You met all the above which makes it stand out. I try to tone down our decorating/landscaping demands at the house, I preach LESS is MORE.
About COG, I just built a modded Super Cub from parts and with a 2.0 COG it is a bit nose heavy. Going to try moving it back by 1/8" increments until happy. When the wind turns down this weekend I will get at it and let you know so we may compare.
Wayne
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steve
Flying officer
Posts: 11
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Post by steve on Feb 19, 2009 2:13:46 GMT 1
Thank you guys for the input.
I used 2 cans of Testors gloss yellow. In the painting topic I outlined the process that I used and explained why I probably wouldn't do it again.
The pushrod openings were covere by pieces of 3X5 card stock with a slit cut to allow the rod to move. I sealed the paper with thin cyano. Just couldn't stand those ragged holes. ;D
I really appreciate the feedback on the COG. Taking it back to somewhere around 2.5 inches from the LE will make a HUGE difference. I never checked the COG on the plane right out of the box and the little manual that comes with it doesn't state what the COG is.
I'll strip out the current nose weight and check where that puts the COG. I just couldn't believe that my painting had added that much weight to the model. Although, I did try and fly it right after it was finished with no additional nose weight and it was very tail happy. So, I expect some additional weight will be in order.
I'll let you know how it goes.
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steve
Flying officer
Posts: 11
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Post by steve on Feb 19, 2009 18:40:42 GMT 1
It didn't go well.  Last night I balanced the COG at 2.5 inches back from the leading edge and reduced my added weight to just 1 ounce instead of 2. Went to take off this morning and the plane would barely lift off and at about 4 feet from the deck it stalled and cartwheeled. So much for the pretty paintjob. What I can;t understand is that it flew so well before I painted it and the paint can't have added that much weight. The only thing I can think of is the battery charge level. How fast do the Nimh batteries lose charge? Maybe there just wasn't enough power to get it in the air. I had charge them fully a few days before. |
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Post by ginginho on Feb 20, 2009 11:55:14 GMT 1
Oh dear Steve, very sorry to hear that, I hope your CoG adjustment wasn't the cause of the downing. That was a lovely paint job you'd done.
I did write about batteries but I've since seen the other thread you have with a lot of info in there from Fly.
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Post by mrmugen on Feb 20, 2009 17:46:33 GMT 1
It is possible the batteries bled off some power. NiMh will loose some sitting....more than most other cell types. How much paint did you use? A few ozs? or a few grams? Remember that most of the plane is behind the cg point so it will require weight up front or a bigger battery. Bigger meaning more voltage, not capacity. Was it tail down while trying to get airborn?
Nice looking cub BTW!
Kevin
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steve
Flying officer
Posts: 11
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Post by steve on Feb 20, 2009 20:14:54 GMT 1
It was very much tail down once it rotated. I had added an ounce of wieght to the nose, inside the cowling down low. I'll try adding an additional ounce and go up from there. I don't think I handled my take off any different than in prior flights. But it is possible that I simply stalled it by pulling up too much. In thinking back, the "paint weight" may actually be significant given the policryl, spackle and multiple primer coats and 2 color coats. I did block sand quite alot between coats but I can see how that could add up.
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