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Old Mar 20, 2012, 08:27 AM
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Help!
Skartec 182 Cessna CG Help

I am relatively new to rc planes and I have been cutting my teeth on a Nine Eagles Sky runner but have now purchased a Skartec RTF 182 Cessna (980mm Wing span).

After gluing on the tail elevator and rudder wing then fitting the main wing and landing gear I have done the usual checks. I have then come to checking the center of gravity.

No where in the instruction manual is any measurements for the C.G so after some reading on the rcgroups and other websites I have come up with the measurements of 1/3rd of wing cord from leading edge for more experienced flyer and 1/4 of wing cord from leading edge for rookie.

The wing cord on my Cessna is 164mm so the measurements I got was 54mm from leading edge experienced flyer and 41mm for rookie. After marking both measurement on my plane I tried to balance with the rookie marks first and the tail dropped down fast. I then checked the 54mm mark only to have the tail fall down again.

I then moved my battery, ESC and receiver as far forward as possible (fixed with Velcro) with little results. I then started adding weight to the front of the plane to find that I needed 40grams of weight to balance at the 54mm CG point .

Question number one is ~ is my measurements for C.G correct for my plane?
Second question is ~ if my measurements are correct is this a common thing for a beginner type of plane out of the box?
Third and final question is ~ To get the CG weight right for my 41mm (rookie) position I have siliconed a 45gram lead weight into a pocket in the front cowl of the plane (see pictures). Is this a good move or should I remove the weight and adjust weight in another method.

Thanks....Mark
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Old Mar 20, 2012, 11:50 AM
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I fly the Skyartec as you describe and I have absolutely NO weights on her added to balance.

The Manual as far as I remember had a CoG mentioned ... page 7 ...

here is the manual in pdf form ...

http://www.skyartec.co.uk/manuals/Cessna182_manual.pdf

As I found as long as you have installed all as instructed and not added anything - it should balance with a mid range 1300 - 1800 3S 25C LiPo in the battery compartment. I actually fly mine with anything from 1300 up to 2100mAh 3S in that box and I never need to trim change. The battery box is dead centre to CoG.

What did you do to make her so unbalanced ?
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Old Mar 20, 2012, 10:34 PM
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Originally Posted by solentlife View Post
I fly the Skyartec as you describe and I have absolutely NO weights on her added to balance.

The Manual as far as I remember had a CoG mentioned ... page 7 ...

here is the manual in pdf form ...

http://www.skyartec.co.uk/manuals/Cessna182_manual.pdf

As I found as long as you have installed all as instructed and not added anything - it should balance with a mid range 1300 - 1800 3S 25C LiPo in the battery compartment. I actually fly mine with anything from 1300 up to 2100mAh 3S in that box and I never need to trim change. The battery box is dead centre to CoG.

What did you do to make her so unbalanced ?
Hi Solentlife, I have made no changes to the plane out of the box except I used 5 min epoxy glue for the tail elevator and rudder instead of the supplied glue. I used the glue sparingly and didn't over do it so I wouldn't think that would make much difference.

I have not flown this plane yet so I can't say if it flys tail heavy and yes my manual comments on CG on page 7 but doesn't give any measurements. Should I remove the weight and try the plane as is out of the box?

I have made some modifications to my Sky Runner and had problems with tail heavy so I know what happens in flight so I am just worried that I will crash this plane on the Madden flight due to my lack of experience.

Thanks....Mark
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Old Mar 21, 2012, 12:59 AM
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If I remember rightly - and I'm actually well away from home so cannot verify .... my 182 balances about in line with the wing struts. But anyway - the manual is clear that the battery box sits across the CoG - so there is no need to state a measurement. You just refer to the halfway point of the battery box.

As I say - I have absolutely no added weights in my 182 - it is as out of box.

I too used epoxy to fit the tailplane.

If it's as per out of box ... you have battery in forward half of the box, Rx and ESC are in the front part of the fuselage ahead of the servos ............ then fly like that - you should not need any weight added. But I hope you checked and replaced aileron / flap hinges from that awful tape they use ? Also take a model knife and cut the coloured tape that crosses hinge lines ....

I love my 182 .... it's the model I use for first flight of day to loosen up .... its aerobatic as much as a high wing semi-symet can be ... it's well powered .... will once you get used to it fly in winds that most others will be grounded ..
Have a look on my Youtube site "solentlifeuk" I have quite a few vids of it flying ... and also on-board keycam vids ...

cessna general flight.wmv (5 min 22 sec)
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Old Mar 21, 2012, 05:57 AM
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Thanks for the help solentlife. The struts on my Cessna comes in line with the centre of the battery box at the bottom of the fuselage. If I hold the ends of the struts where it joins the wing and balance the plane it still falls to the tail even with the 45g lead weight fixed to the front.

I havn't changed the tape on the wing joints but I did look at them and thought they looked quiet average so I will go ahead and change them.
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Old Mar 21, 2012, 06:21 AM
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Originally Posted by West Oz Mark View Post
Thanks for the help solentlife. The struts on my Cessna comes in line with the centre of the battery box at the bottom of the fuselage. If I hold the ends of the struts where it joins the wing and balance the plane it still falls to the tail even with the 45g lead weight fixed to the front.

I havn't changed the tape on the wing joints but I did look at them and thought they looked quiet average so I will go ahead and change them.
Something is definitely wrong .........

How far behind the struts do you have to pivot the plane to balance it ?

I may be travelling home next few days ....... I'll check out my 182 then.

The video I posted is absolutely stock out of box apart from sorting the rubbish tape hinges and I fitted a 1800mAh 3S 25C LiPo ... gives me near 9 mins flight.

I do use APC props and not the Skyartec ones ... but that would not change CoG
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Old Mar 21, 2012, 08:41 AM
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Originally Posted by solentlife View Post
Something is definitely wrong .........

How far behind the struts do you have to pivot the plane to balance it ?

I may be travelling home next few days ....... I'll check out my 182 then.

The video I posted is absolutely stock out of box apart from sorting the rubbish tape hinges and I fitted a 1800mAh 3S 25C LiPo ... gives me near 9 mins flight.

I do use APC props and not the Skyartec ones ... but that would not change CoG
The centre of the strut is 42mm from front of the wing and the balance point without any added weight is 68mm from front of wing so about another inch past the centre of the strut (aprox 41% of wing)
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Old Mar 21, 2012, 10:46 AM
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Originally Posted by West Oz Mark View Post
The centre of the strut is 42mm from front of the wing and the balance point without any added weight is 68mm from front of wing so about another inch past the centre of the strut (aprox 41% of wing)
I'm surprised that no-one else has chipped in with their 182 info .... it's a popular model and there must be plenty out there. HK stock goes Backorder quite often.

With regard to weight and fixing to model .... I would not use the cowl. If I had to fit weight - it would always be either to the firewall where motor is mounted or in form of useful battery weight.
The cowl is not so strong to start hanging weights of.

OK - I forgot a couple of tips :

1. Replace the grubscrews in the nose wheel joiner with short machine bolts. Then you can tighten it nicely to stop wheel getting out of line - which will happen with the grubscrews. There is no need to change the nose wheel assembly. BUT if your 182 really is tail heavy - you could swap the nose wheel assembly for a heavier one piece affair.
2. Check the plastic frame that is glued to the front of fuselage which carries the motor. Mine came away after about 20 - 25 flights where the glue was thinly applied .... I 5 minute epoxied mine back more secure.
3. Same with servo tray and the wing pin plate ... check they are well glued in - mine at similar time to motor plate needed glueing back in with 5 minute epoxy.

Later repair tips :

Wing struts - these are essential to stop wing folding - so never fly without. But you may sooner or later break one. To repair - take 1.5mm drill .... drill into broken ends of both sections ... take short piece of cocktail stick and epoxy into the holes pushing the two sections together. tape rind to smooth the glue joint and bingo - strut is fixed and strong. No need to get new.

Skyartec deal direct online ...

http://www.skyartec.com/Product.asp?...me=Spare parts

and this is the link to their spare parts pages.

I have dealt with them and they are very good. I had new motor shaft and cowl from them with reasonable shipping cost and well packed.

Like I said ... I will check out my 182 when I get home and let you know about my CoG ... unfortunately I am away on assignment in Ukraine and don't know when I go home ... hopefully it's in next few days.
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Old Mar 22, 2012, 07:38 PM
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One of the servos fell out of the wing before I could fly the plane so re-glued both them back in and checked over the plane but forgot the engine mount so will go back and check that thanks.

It's blowing here at the moment so no flying and I am still learning with the Sky runner. I have put a order in for a AXN floater so when that arrives I will practise with that before I move up to the cessna (bit more forgiving) so plenty of time.

Am I being petty with the measurements I mentioned or do I need to be that precise?

Thanks...Mark
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Old Mar 23, 2012, 10:38 AM
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Unfortunately like most models near finished out of box - glueing tends be with crap glue and poorly done.

My Servo mounts in wing were also poorly glued in and I had to redo them.

To be honest ALL the plastic parts - such as the nice wing fillet protectors either side of fuselage - they came off .... the plastic peg plate at front of wing came loose .... the wing strut plates came loose .... motor mount frame ...

But this was all after considerable amount of flying and I do really throw my 182 around the sky as you saw in prev. video.
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