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cg or trim issue...

taeho98

Junior Member
#1
so....

Right now I'm 15 years old and a noob in this awesome hobby. I bought myself a hobbyzone champ because everybody tells it's a good beginner plane... Well, I soon found out that even what people call a beginner plane isn't even that easy to fly.
I already have a great nano qx and know pretty well how to fly it for some reason. I'm still learning though, but I thought maybe because I can fly a multirotor a plane shouldn't be hard to learn...

NO.

my longest flight was about 7 seconds and it looked horrible. :(
When I handlaunch it, The first thing it does is noes up and then it tip stalls to the right...
I trimmed it but that just doesn't work. It flies straight for the first 6 feet and then goes up again. It's not the wind because there was none.

The manual says ~28mm from the leading edge should be a good cg but it doesn't fly straight and the trim doesn't do a good job either...

help???

ps I'm new here and maybe this threat is in the wrong place. Sorry...
 

RAM

Posted a thousand or more times
#2
Not sure if you did this or not. You should check it every time before you take off. It does sound like it's tail heavy

Here's my first attempt at flying. I'm a rookie too, just an old rookie :)
You can see in the video how tail heavy my first plane was.
I added some nose weight to balance cg and managed to get it into the air
https://www.youtube.com/watch?v=f5Yj6LsEoqo
 
Last edited:

taeho98

Junior Member
#3
I've added some nose weight and it does fly alot better, at least it flies more straight than before :)

I do have to carry a little more speed what is a little hard sinds I don't have a giant space to fly....

but thank you for the reply!
 

Ron B

Posted a thousand or more times
#4
I don't know about the champ but if it is like the duet you have to check every thing before each launch as it is so fragile it will get out of shape real easy. I tell every one to start out with the Delta Ray as a beginner plane but it needs some room to fly. the duet and from the videos I have seen the champ have to be flown from launch to landing. If you can do it you WILL be able to fly. The delta ray gives you time to take it easy and relax and also move on up with your flying skills. I let a friend fly mine who just got started and he liked it so well he bought one the next week and he is a very aggressive flyer and after 2 weeks he is flying like he has been doing it for a year or more.
A lot of people have learned to fly on the champ so keep at it, check all of your alignments and control surfaces, and your cg. If you can find some one who already flies get them to help you, besides it is more fun to fly with some one else.
Welcome to the forum and good luck
 

taeho98

Junior Member
#5
So I've added quite some weight to the nose and it still does climb a tiny bit. but at least I can fly it properly now!
take-offs are decent and I can now make pretty good left-hand turns and remain on altitude.
landings are a bit hard though...
But I'm getting more and more exited about the hobby by the minute!
 
#6
this sounds like what my Duet does. it went up and down like an old wood roller coaster. I flew it yesterday, remembered something about cg so moved the battery as far forward as I could. It definitely helped. Mind you on my first flight I crashed and broke off the tail fin, so I have a little less weight out back. my duet didn't come with printed instructions I had to download them but I don't remember anything about cg in them.
 

IFlyRCstuff

Flyer Of Many Things
#7
It isn't suprising that it goes up a little, throttle =lift regardless of if you are adding on to it or not (this is only and primarily for small and undercambered wings, not larger, less undercambered wings) how much nose weight have you added, I have never flown, or see someone fly the champ, I started about 5 steps to early, but back to you. Are you losing altitude with right-hand turns, or what? ?? Also a tip for landings, if you can't get a straight approach low enough to go smooth, go out, come back high and turn to progressively lose the altitude, but learn level turns first, Hope I helped, HAPPY FLYING :D
 

taeho98

Junior Member
#8
I know that because of lift the plane should go up but this isn't lift... I know how lift feels when flying it because there's always some wind and I notice it when it gains lift...
what happends is that the plane wants to go into a stall, nose up position and get itself into an oscillating stall. when I give it no throttle the plane goes into a perfect glide path, so my cg isn't too far off I guess.
It sort of feels like the tail is crooked but that isn't the case. At slow speeds it's flying perfect but when with half throttle it starts pitching up and I always have to give it some down elevator. when I'm in a turn I never have to give it up elevator because it's doing it by itself...
yes, it's a little beaten up but nothing is crooked... and the elevator is even pointing a little down because of the trim...
 
#9
okay I flew it this morning and really payed attention to what I was doing and what the plane was doing and found a few more characteristics. I don't know how much longer my Duet will last though, as the fin is already broke off and now the rear stabilizer doesn't sit flat. I finally remembered something about CG and trim so first thing I did was plug in the battery and center the trims on the radio. The elevator indeed was angled up a little so I neutralized that. I also moved the battery as far rearward as I could. This all helped a lot so now I am thinking maybe my Duet at least was/is a little nose heavy. I have not been able to find out any info online about where the CG should be on the Duet. The wings did dip in turns, but I realized on this mornings flight I tend to give a little elevator input automatically anyways so I'm not as worried about that. It did seem to have a little more difficulty turning right direction than it did left but it was hard to tell, the wind started to come in and where I was flying I basically had to fly in an oval that was always cross wind. I did get some oscillating stalls again, I noticed as taeho mentioned it happened with throttle, but all I had to do was chop or reduce the throttle and the sticks go and it fixed it self. It did glide then I totally chopped the throttle so I think I have balance issue worked out.
I may try flying later today again, but like I said the Duet is starting to see some battle damage that may alter her flying characteristics. I think I would still recommend this little plane to others, but with a warning about landing on hard surfaces unless they are already a proficient flyer (which I am not).
 

IFlyRCstuff

Flyer Of Many Things
#10
Try simply putting the cg more forward, I find that the manual isn't perfect, I have had experiences where the manual said 62mm from the leading edge, it needed to be at 57mm to fly good.
 

Ron B

Posted a thousand or more times
#11
my duet turns better left than right and I think I need some trim on the tx but it has been a bit windy the last few times out so I haven't been able to do a real test.
 
#12
I know that because of lift the plane should go up but this isn't lift... I know how lift feels when flying it because there's always some wind and I notice it when it gains lift...
what happends is that the plane wants to go into a stall, nose up position and get itself into an oscillating stall. when I give it no throttle the plane goes into a perfect glide path, so my cg isn't too far off I guess.
It sort of feels like the tail is crooked but that isn't the case. At slow speeds it's flying perfect but when with half throttle it starts pitching up and I always have to give it some down elevator. when I'm in a turn I never have to give it up elevator because it's doing it by itself...
yes, it's a little beaten up but nothing is crooked... and the elevator is even pointing a little down because of the trim...
You have a thrust angle problem with the motor not a CG issue at all. If the plane has a good glide slope without power but with power noses up even at half throttle you problem is that the motor needs to be angled down slightly and if it pushes up and rolls to the right like I suspect from your stall rollercoaster description you may need 2 flat washers under the top motor screws and one on the right bottom to give you down and left thrust. Hope this helps, had to do this on a few planes to get stable flight. Good luck.:cool:
 

taeho98

Junior Member
#13
You have a thrust angle problem with the motor not a CG issue at all. If the plane has a good glide slope without power but with power noses up even at half throttle you problem is that the motor needs to be angled down slightly and if it pushes up and rolls to the right like I suspect from your stall rollercoaster description you may need 2 flat washers under the top motor screws and one on the right bottom to give you down and left thrust. Hope this helps, had to do this on a few planes to get stable flight. Good luck.:cool:

well. I will try to film it next time I'm going to fly to show it's crazy-flight. But it aint a thrust angle problem since the prop almost hits the bottom part of the nose due to the angle on it....
 

IFlyRCstuff

Flyer Of Many Things
#14
Would your battery be slipping in flight? If it has a good glide, but noses up when adding throttle imhave found through personal experience, the battery slips, then gets slid back foreward upon a not-exactly-perfect landing.
 
#16
Ok taeho98, got another possibility for ya as I just scratch built a swappable Corsair and it had a rise issue as I throttled up and didn't need elevator input when turning when over 1/4 throttle setting. It turns out that because of the wing design the ailerons were not level with the bottom of the wing and acted like flaps were always extended causing weird flight almost like a tail heavy plane when throttling up. Check it out and see if you have that issue. If I hadn't been thinking of your issues I likely would have missed this one and just blamed my building skills.
 

taeho98

Junior Member
#17
hey edfjockey, I would love to see your corsair fly because I love those :) but unfortunately, the champ does not have any ailerons... just rudder and elevators
 
#18
Yeah, gotta work something out for that as I normally fly alone in my 47 achre back yard and when I tried to use the videocamera on my Iphone mounted to my hat,but didn't work worth a damn. Sorry I didn't have a solution for ya, kind of used up my possibilities.
 

taeho98

Junior Member
#19
YOU ARE ALLOWED TO LAUGH

so... the last few days the weather wasn't that great and it was pretty windy. Because the champ is so light i couldn't fly the past few days.
It did give me some time to think though...

I came up with a new beginnertip for me:

On the transmitter, your elevator is inverted, up is down, down is up.
the same applies to your trim... :cool:

yeah, I know I trimmed it the wrong way.
I just flew it about 10 minutes ago with no wind at all, It flew like a champ!
no terrible oscillating going on anymore. It still wants to go up a little, but that's ok. It keeps me reminded to carry enough altitude at all time and to stay one mistake high.

I also learned is when you think your battery is dying. Stop, it probably is. I never was capable of flying long enough to learn this earlier so now I know to listen to myself and not to try to find the end of the battery...


I want to thank you all for the great support and amazing suggestions!
thanks to you guys I'm really liking rc flying alot more and I really want to stay up in the air!

Thank you!!!!