cubflipper02

ok,let me preface this by saying I've been in the hobby 10 years,fly everything from 1/2a to 33% .Here's the dilemma.I'm on my third 1.20 h9 cap,built the first for a friend and it flew great.Built the second for me and also flew great to the point I had to retire it.So on my third one,I figure what can go wrong?First flight today,no wind ,really nice day.Saito 1.80 for power.Hitec 605's all around with one on each elevator half up in the fuse with fiberglass pushrods.Balance is spot on,incidence on wing and tail both are 0,0.take pretty uneventful,but trying to keep this thing in the air was a battle.I thought I was getting radio interference,kept flying hoping it would go away,it didnt.Plane kept bopping up and down,trying to drop a wing once in awhile.I thought it must be cg,but no.I even gave full up elevator in normal high rate and it didnt snap out like most caps.I can not figure for the life of me what the problem is.Only two things are coming to mind,one is the elevators and stab do have a twist,but so did both the other caps I've flown,almost the same exact twist.Example would be the left elevator is inline at the root end,but the balance tab is lower at the tip.The right elevator is fine.I adjusted it some more and will try tomorrow,but I dont really think that is the problem.The only other thing I can think of is the servos are a little older 605's,maybe they are not holding in the air?I dont know.I'm really stumped and hope somebody can offer some ideas.Also my manual on the cg says 5 5/8,is that what everybody elses says?I cant remember from the previous planes if it was this.I know sometimes they update cg's and such.HELP PLEASE!

Mike Bogh

My Feedback: (14)

Hideho,
So how old are your 605's ? (great servos BTW)
Sounds to me like their not centering consistantly.

I'm having trouble with a plane behaving the same way you describe. After watching the servos on the ground for 10 minuets or so, I found the servos not centering exactly aprox 20% of the time. I'm thinkin' perhaps the pots are showing signs of wear.
Also are your ailerons dropped a wee bit? (drooped)
This will also make the plane behave the way you have described.
A combination of both is possible but not likely.
It doesn't take much drop to make a difference, BTW, I have the same plane w/Saito 150.

daveopam

My Feedback: (9)

You didn't say how your elevator servos are driven. Are they run off different channels, Y-harness, miracle Y ?
I would start by swaping them. Then tie the bird to the ground, run up the motor and work the control surfaces.
See what happends. later daveo

cubflipper02

I'm really starting to lean towards the servos being the problem.They are driven through a mix in my 9Z.After messing with the plane for another 2 hours last night the only conclusion I can come to is the servos are not centering.I think they are played out.They must be at least 2 years old.Thanks for the brainstorming guys.

3dd

My Feedback: (6)

sounds like you might have some freeplay in the control rods.check if you can move the control surfaces up or down with radio on but no imput.i would take the elevators off the mix and put them on a miricale y from maxx products and that way you have a mirror image of control and a centering pot to adjust the center of one of the servos.be sure to check if you have a loose hinge or a big gap in the mating edeges

cubflipper02

no need to remove them from a mix.On the 9Z,you have infinite adjustability.I've pretty much figure it to be play in the servos with some flex in the pushrods.Installing new servos and rods tonight and will report tomorrow.
Thanks all

Goliath

Get some better servos...the 605 has such a bad centering problem they even make my r/c boat hard to drive. Hitec has some econo digital out now and reports are very good.

cubflipper02

whoops,sorry for never posting the end results.I did replace the servos with 5645's and it helped,but I would still get some weird motions from the airplane.I range checked several times and never found a problem.I figured I would move the antennae to the outside of the airplane,when doing so I found a split about 4 inches from the end of the wire,looks like there was some intermittent contact between the broken pieces of wire.Fixed the antennae and now everything is back to being super fine.That was a new one for me.

Mike Bogh

My Feedback: (14)

Hideho and good morning...
Kind of a bummer that you had to throw $$ at the problem before you discovered the real problem....I hate when that happens..

I have learned that lesson over and over when it comes to my vehicals...proper diagnostics are sure a money saver when you keep throwing parts at your problem trying to fix it.

Unfortunatly those lessons don't transfer as well to our models.
Glad you got it nailed down tho...

cubflipper02

Luckily I already had the 5645's on hand,the project they were destined for was sold so it all worked out in the end.

ifly2

Sound like the luck, was finding the break, before it found you... I had an antenns come apart about 1 inch from the receiver a while back, luckly, I found it during the range check... Good luck

Les

monster56

I have a great planes 80in wing cap-21 with a 2.10 flew stupid like yours (all over the place like glitches) all flight controls at neutral recomended cg at about 51/2 installed 4 ounces at the firewall flies absolutly awsome...try some cg weight at the front! be carefull best wishes..