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Trimming Questions

Old 05-12-2012, 12:43 PM
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lablover
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Default Trimming Questions

Ijust finished putting together a great planes Sequence to do some light practice at a local church field. Lots closer than the club field....Anyway

I guess some of the questions apply to all planes and being I'm pretty new to RC they may be silly questions.

On the sequence Iset up everything by the manual. On the maiden flight Ihad to give it a lot of left aileron trim to get her to fly straight. When Ilanded you could see the AIlerons were now offset and not even with the wings when first set up. Iguess what I'm asking is what causes this? IF I put the ailerons even with the trailing edge of the wing in wants to roll or bank to the right. After trimming it flies fine but those ailerons are deflected alot. Not even sure deflected is the right word.

IS the plane more heavy on one side and this is what is causing this?

I also notice this on rudder as well...Dead center but when I go to do a stall turn on the way up, the bird wants to drift to one side.

Is there a site, or PDF or something that can explain why this happens? On my sport planes, warbirds etc, I trim it out on the radio and never give it another thought. With all this pattern stuff, Iwant to know why and try to fix it.

FYI..my wife says I'm very Anal retentive

Look forward to some info..Thanks a Million
Old 05-12-2012, 01:04 PM
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woodie
 
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Default RE: Trimming Questions

For the ailerons, more than likely, there is a twist in a wing panel (or both). This is not unusual in open framework wings with monokote type covering. You can often remove the twist by heating the monokote while twisting the wing panel in the opposite direction to the twist. Keep working with it until the ailerons are neutral.

Beyond that, there are some procedures for trimming that go step by step. The NSRCA website has one of them. check the link below.

http://nsrca.us/index.php/all/flying/177-trimchart

Woodie
Old 05-12-2012, 01:04 PM
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cmoulder
 
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Default RE: Trimming Questions

OK, we'll find out how AR you are...

Try [link=http://www.rcuniverse.com/forum/fb.asp?m=10011263]THIS[/link]
Old 05-12-2012, 01:10 PM
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lablover
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Default RE: Trimming Questions

Hmmmm, I was just reading this

http://www.hebertcompetitiondesigns....ngulation.aspx




ORIGINAL: cmoulder

OK, we'll find out how AR you are...

Try [link=http://www.rcuniverse.com/forum/fb.asp?m=10011263]THIS[/link]
Old 05-12-2012, 01:29 PM
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cmoulder
 
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Default RE: Trimming Questions

That is, for quite a few guys, the "trimming bible".

But I would agree with Woodie that something is twisted somewhere.

You can't start trimming until the plane is straight!
Old 05-12-2012, 04:19 PM
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Jetdesign
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Default RE: Trimming Questions

One thing, the triangular trimming method can't be used on the Wind110 unless you want to change the way the wings are connected to the fuse - our plane has no positive angle in the wings, thus requiring up elevator to fly straight and level. (BTW the ESC mounted off to the side of the fuse is enough to throw off lateral balance. If your Rx battery is on the same side, or anything else (rudder servo?), it all adds up.

You shouldn't need to do much with this plane - this is what I've done in working with a local FAI pilot:

For axial balance (what we call CG), trim for straight and level, pull to 45 degree upline, and roll inverted. The plane should almost hold it's track, just falling off the line with nose down. If it continues straight or noses up, it's tail heavy. if it noses down hard, it's nose heavy. I think this applies to planes without positive wing incidence, but not 100% certain yet.

For lateral balance, trim the plane with radio to fly straight and level. Now roll inverted and fly straight and level, hands off. If the plane rolls heavily in the same direction that you added trim, it's a balance issue. (Use a stick plane, or envision a plane with a heavy right wing. It will take left aileron to fly level. When you roll inverted, the heavy wing is now on the left side, and the left aileron trim will add to the imbalance.)

Use your radio to trim for vertical climbs and dives. Fly straight and level, pull to vertical climb at high power just in front of you, and watch. Use a mix to add up or down elevator as needed. My plane didn't need much, if anything. Then do the same, but fly up high straght and level, and push to a dive, and mix out any tucks or climbs. My plane wanted to climb out, so I added some down elevator at 0% throttle. This will hurt any other line if you drop to 0% power though, but you want to keep a small amount of power and have air moving over surfaces during most maneuvers anyway.

I would venture to say this is enough to get you flying your plane very well through the first few classes.
Old 05-13-2012, 02:49 AM
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lablover
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Default RE: Trimming Questions

As usual, great info. I'll apply some of it to the little Sequence and see what happens. Ihave not flown the wind enough yet to notice any bad habbits. Hasn;t stoped raining here...Grrrr

Thanks again
Old 05-13-2012, 08:37 AM
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Default RE: Trimming Questions

I had the sme trouble with my Sequence and finally noited that the holes for the anti-rotaion pin in one wing had been drilled oversized a little so that when I glued in the pin it was at slight angle and changed the incidence of that wing.

I used an incicdence meter (Horizon Hobby) to set it even with the other wing by enlarging the hole in the fuse and using a piece of light ply to secure it.
Old 05-13-2012, 01:09 PM
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Jetdesign
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Default RE: Trimming Questions

Good catch lablover - I missed the part about the sequence since i know you've been working on the Wind. You might have more freedom with the sequence to make changes, thus trimming would require more work (like Gulliver's experience).

The Wind really doesn't need very much...
Old 05-15-2012, 05:12 PM
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lablover
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Default RE: Trimming Questions

Hmmm

Time to go buy a incidense meter....Learning every day

Thanks


Garfield...Good info on the wind as well


ORIGINAL: Gulliver

I had the sme trouble with my Sequence and finally noited that the holes for the anti-rotaion pin in one wing had been drilled oversized a little so that when I glued in the pin it was at slight angle and changed the incidence of that wing.

I used an incicdence meter (Horizon Hobby) to set it even with the other wing by enlarging the hole in the fuse and using a piece of light ply to secure it.
Old 05-15-2012, 06:39 PM
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cmoulder
 
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Default RE: Trimming Questions

Get the [link=http://www.hangar-9.com/Products/Default.aspx?ProdID=HAN192]Hangar 9 digital incidence meter[/link] and [link=http://www.horizonhobby.com/webapp/wcs/stores/servlet/SearchCmd?searchKeyword=extension+bar&filterTerm=&searchType=productgrid]extension bar[/link]. Very useful.
Old 05-16-2012, 11:13 AM
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Default RE: Trimming Questions

For what you are saying for the problem of the airerons can lead to one main thing.The servo horns that are conected to the servo are not at a 90 degree angle.What will help is to take off the control rod off , un-screw the screww that is holding the servo horn and remove the horn and then re-attach it as 90 degree as you can. The put the screww back in.This makes sure that both servo's for your airerons have full throw, because it sounded like one was doing the job but the other was ether to far forward or backward.Now take the rod and reconect it back to the servo hord and make sure that the aileron is level with the rest of the plane.If not keep twisting the conter till you get it level with the rest of the wing
Old 05-18-2012, 10:52 AM
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Jetdesign
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Default RE: Trimming Questions

For the plane drifting during stall: the prop spins and sends the air spiraling over the plane, and creates a spinning mass in the front of the plane. These conditions would cause the plane to fly off at some angle other than straight ahead. Arf planes typically have some right thrust built into the firewall to compensate. However, the amount of thrust offset you really need is dependent on speed and rpm, not a fixed value. As such, the plane will drift different amounts in different conditions, probably trimmed to fly straight at cruise. It is very noticeable in a stall turn with an abrupt change in rpm and velocity, as well as a birds eye view of the plane.

The options are to live with it, change the thrust angle to suit a different flight condition, or mix rudder to throttle.

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