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Old 03-02-2006, 09:17 PM
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Primodus
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Default CG check

This is a Great Planes Cessna 182 Skylane ARF. AUW is 7.5 lbs. It is sitting on the CG machine at exactly 3" per the GP website and the manual. (I check both just in case of updates to the manuals) As you can see in the pics, it is sitting at about a 10-15 degree nose heavy angle. I have flown it like this, but now I am wondering if a perfectly balanced CG would justify the added weight. Any thoughts? I guess it would take about 2oz to make it balance outright. Discussion is welcome and appreciated.
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Old 03-02-2006, 09:23 PM
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Default RE: CG check

The plane will not notice the difference in weight. It will be fine.
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Old 03-02-2006, 09:29 PM
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Default RE: CG check

Rather than add weight I would recomend moving the battery back to the rear more. I have the same plane and it has in my opinion a rather high wingloading to start with, so I moved the rx battery and servos, so I could to make it balance out rather than add more weight.
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Old 03-02-2006, 10:08 PM
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Default RE: CG check

What motor are you using iron eagel? Mine is a Saito 72. I also have flaps added, each using one servo.
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Old 03-02-2006, 11:28 PM
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Default RE: CG check


ORIGINAL: Primodus

I have flown it like this, but now I am wondering if a perfectly balanced CG would justify the added weight.
I have to disagree with w8ye on this one. My answer to your questions is... OH MY GOD, YES!!! I'd much rather fly a perfectly balanced plane that is a touch heavier than a nose heavy pig any time. Two ounces in the tail is nothing for that big wing to lift. With the model balanced more reasonably, the elevator will respond better, you'll be able to land slower, and flair easier. All that said, if you can move the radio gear around without having to add weight, that would be best.

Here's something else to consider: what happens when you fill the tank? How much more nose heavy are you then? I'll bet a good 10 to 12 ounces!
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Old 03-03-2006, 11:05 AM
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Default RE: CG check

I am using an OS 46 FX spinning a 14/6 three blade master airscrew. Funny, I have considered putting flaps on mine also to lower the landing speed. Mine was looking for about four ounces in the tail to balance so that is why I moved the position of the internal gear rather then add weight. It came in at 6.4 lbs dry weight, and when it is fueled up around it has a wingloading of around 30-32/oz per foot. Due to the heavy wing loading I usually use around two hundred feet of runway each time I land.
It is a nice plane, with a good scale look to it. I think it is a good trainer for flying a high wingloading aircraft such as a warbird. I think it would fly real nice with a saito 72 four stroke in it, But it does real well with the setup I am using now, the only drawback is the hot landings which could be tamed using flaps.
If I may ask how did you do the flaps on yours? I really think that they are needed on this plane, besides I like complex airplanes anyhow.

BTW I tossed the wing spars which came with it when I had the ca hinges fail twice on me and switched over to metal ones. Also I would sugest that you screw the servo mounts to the plywood covers on the aileron servos using epoxy alone I have had one mount fail, real interesting flight that time.
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Old 03-03-2006, 11:15 AM
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Default RE: CG check

There is a very spicific post on RCU that addresses te flaps mod for this ARF. I will try to find it ASAP and post a link. It's a very easy setup to make, I don't think it took long to do. Using flaps, the landings are a breeze. It's very trainer-esque, landing in less than 100 feet rollout included.

I am surprised that you are using such a large prop on the 46FX. A 14/6 3 blade?? can that be real?
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Old 03-03-2006, 11:25 AM
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Default RE: CG check

Regarding the prop, yes that is real it may be a five but I think it is a six pitch looks a lot like the one you are using. It is not all that great a low revs but up in the air she really flys sweet. While it does not produce a lot of static thrust it does perform well in the air and does not unload at all at speed. Not to mention it looks cool and given the fat fuse it really does perform better than the 12 inch I had on it before. I also added ducting for cooling the motor as it is total enclosed. Yes the motor is over proped but seems to work well so far.


I also use a big spinner (2 inches) which helps the prop perform a bit better...
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Old 03-03-2006, 11:43 AM
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Interesting, I am using a 12x6 3 blade on the 72. I have to admit it flies very smoothly and has great power. (The sound is great too)
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Old 03-03-2006, 07:39 PM
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Default RE: CG check

I was wrong about the prop it is a 13 inch 3 blade 8 pitch. The 14 inch is on my TF Mustang with the .60 on it.
To be honest, I tried several, two and three blade props before I got to one which performed as I wanted it to on the Cessna. I have several planes and forget at times exactly what setup is on which airplane.
I think the flap idea is a real plus for this bird, I am going to do a search and see if I can find the thread that you mentioned.

I love the sound of the Satio four stroke engines, not to mention they are very good engines to boot.

I am building a 1/5 scale cub (next year or late this summer) and I am going to see about geting a saito twin cyl for it (bit pricey but the plane needs it, lol). I still have two planes in the build que before it (for my wife and daughter) and I am still finishing up one I have been working on for two years. So the cub Kit is tucked away in the closet till those are done, so I have plenty of time to save up for that one.
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Old 03-03-2006, 10:42 PM
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Default RE: CG check

check out this link on the flaps thing, page 2, post 48 of the thread (scroll way down), lots of detailed pics.

I used monokote for the hinge material, works flawlessly, but hinge points are cool too.

http://www.rcuniverse.com/forum/m_14...Ccessna/tm.htm
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Old 03-04-2006, 09:56 AM
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Default RE: CG check

I have a GP Cessna with OX .46 FX. It was balanced just slightly nose heavy. Flow only once.
It required a very fast landing. I have since rebalanced toward the aft and added a flap function to the airleons. Will fly later today and find out if this helped.

Word of caution if you land on grass. The front wheel pant does not have good ground clearence. When I landed (fast) in the grass, the grass caught the pant and forced it into the belly and broke the skin and stringer. Upon repairing, I removed the front wheel pant to prevent this from happening again. Hopefully, rebalancing slightly aft heavy will solve the landing problem.

The OX .46 is paired with a Zinger 12x5 prop. That combination worked very well.
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Old 03-04-2006, 08:42 PM
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Default RE: CG check

Primodus
Thanks for the link about the flaps, my GP Cessna is about to get flaps installed. It is nice to see the inside of the wing before you make an attack like this on it.

I will probably have it done about the same time mud season is over.

I thought about moving my wife's LT 40 wing off the bench and starting on it tonight. But she was so excited last night when I started on "her Plane" that I haven't got the heart to do that to her.
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Old 03-04-2006, 10:45 PM
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ORIGINAL: iron eagel

I thought about moving my wife's LT 40 wing off the bench and starting on it tonight. But she was so excited last night when I started on "her Plane" that I haven't got the heart to do that to her.

More like you enjoy sleeping in your own bed, versus the doghouse! LOL Looking forward to seeing the flaps mod when you get her done.
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