SE5a alignment problems
 

So after more than a year, I'm pulling my SE5a out of mothballs hoping to get it into the air when the weather calms down. It's only flown a single handful of times and each time it was a handful. The first flight was a wild ride for balance reasons. On the remaining flights I had to do everything I could just to make it fly straight. I would't turn right. Even with full right aileron trim, I couldn't get it to turn right.

And that's where I left it...intending to check it for alignment issues. But then I got involved in other things, our club lost its field, and I returned to building my Albatros CI.

Anyway, I decided to start with a little photo analysis. As you can see in the photo below, there are some major alignment issues. It's hard to believe I didn't see this before. Obviously the right and left wing panels have different degrees of dihedral (I've leveled the model and straightened the photo do have the center section level) and one side of the elevator is not square.

Would this deplorable state of affairs have resulted in model's desire to pull left? Obviously, I'll have to re-rig it.

On the other hand, maybe I'm looking at the model wrong. In this version of the photo, I've leveled the wingtips and everything looks good (including the vertical fin alignment, elevator, and UC) but the center section looks a little off.

Which is "right?"

Note: Before the flights I checked the incidence of both top and bottom wings at several stations and that all looked perfect.

I think the center section is off, but how this affects fight - you're the pilot, you tell us.

It has been my experience over the years that I could make just about make anything fly.....no matter how out of alignment it was. This doesn't look like it is far enough out that it wouldn't fly or be controllable. Its hard to tell from way over here.........:cool:.

Seriously, most of the answers are found by holding radio and flying the darn thing.

Last time I flew it I had the aileron trim all the way to the right...and, even with full right aileron input couldn't make it turn right. I suppose this might suggest an engine alignment problem. At present (if I didn't make any mistakes) the engine sits at 0-0.

Here's my last flight report from the RC Groups build thread:

"Third time's the charm...or so I hoped.

So, after a moment to calm my nerves, I opened up the throttle and off it went down the field. But as soon as it was airborne, itveered terribly to the left and it looked (again) like I was going to lose it. But by holding in full right aileron I managed to get it leveled off and climbing to a safe height.

Once it was "three mistakes high" I dialed in enough right aileron trim (and a couple of clicks of up elevator) for more-or-less straight and level flight. It was still pretty skittish in the air (or maybe I was skittish on the ground) but after a couple of heart-thumping circuits, things seemed "under control" and I started bringing it down and closer for the photographer. I was fearful of another deadstick, but the engine seemed to be performing well (and had checked out well pre-flight).

Basically all I did was fly in big counter-clockwise circles. It definitely didn't want to turn right. I suppose I didn't have much aileron left and I was afraid to use much rudder...which probably would have done the trick. So I just kept turning left. I had set the Tx timer for 5 minutes for the smaller tank...and I suppose I flew for about 2 minutes after the warning tones. I called for a landing and brought it around onto final. There was a moment, when it veered again but I straightened it out and it cruised in for a very smooth and I thought elegant two-wheel landing with the tail scale high. Then the tail came down and the flight was over. And then it hit a bump in the field and slowly flipped over.

So what did I learn? That this is probably never going to be an easy, lazy flyer. But, you know, that's OK. I don't need an easy, lazy flyer. I need a scale WWI model that will prepare me for flying future scale WWI models. And, if IT survives MY learning curve, the SE5a should do just fine."

http://www.rcgroups.com/forums/showt...363887&page=82

I just added it up and I have flown/own 9 different versions,sizes, manufactures, etc of Se5's and se5a's. And several of most of the manufactures. All flew well, some VERY well. Some required tweaking. All of thes planes pull to left because of engine torque and benefit in varying degrees with some right thrust. But i normall set my own up o-o, and don't have issues.

I agree with Art, and what i recommend to many new to WW1 flying is just fly the airplane. If it needs right trim, mecanically put some in and fly it, keep making changes until you get it right. It will probably respond beter with right rudder than right aileron. We fly these mainly on the rudder, with aileron to correct/help the rudder. learn to use your left thumb. Set up aileron differential, more up than down. Most of WW1 birds have very little down aileron.

But, also like Art said. It's hard to recommend this far away and without being able to fly the bird.

Makr sure you have no left thrust in the engine...

above are random thoughts, obviously

SE5a are the greatest

steve p
www.hoosierdawnpatrol.com

Hi, First off nice bird! But it is miss behaving! For what it is worth I have been scratching and flying scratch built large scale ww1 airplanes, N28s, Dr1s, N17s, for about 10 years now. I belive in the ASAP rule..as straight as possible. It is true that out of allingnment planes will fly..I have flown a few myself but....I also have found that the ASAP rule is worth the effort. I would get everything as close as you can to straight and any wash out in the wings equal. I have never flown a golden age, WW1 model without at least 2 degrees, or a little less, of right and down thrust in the engine. This is a good starting point and in all honesty I can not imagine flying that type of model any other way. You could get it straigh,t if possible, and start with a degree or so of down and right thrust in the engine and see how the bird responds. Then go from there. If the wings and verticle incidence is correct to the centerline and any wash out in the wings are even this should solve your problems. You might want to check the latteral balance too although I usually ignore it on this type of model with one exception when a Dr1 I had had balancing weight on the left side of the fire wall, It was the only place to put it. Getting this Dr1 balanced latterally made a difference in how the bird flew at slower speeds ...it would fly even out of latteral balance but could get scary at lower air speeds. Best of luck !

Sorry I take it back about engine thrust line at least on an Se5. I have old Dave Platt plans for an exact scate version and he calls for 0 0 on the engine. Steve is absolutly correct on that. I admit I have never flown an Se5 but am certain something is a miss on yours and that you will get it sorted out.

Abufletcher- the left wing(s) appears to be twisted. The LE of left near the tips is lower than TE relative to the right wing(s). Parenthesis used only because the upper wing is the one I'm basing opinion. Block fuse, loosen rigging and 'X' bracing, jig lower panels, set the 'X' bracing then re-rig. Since it has fwd stagger the lower wing needs ~1/8 to 1/4" more incidence. If it was my airplane I'd rig the TE at tips to have ~1/8 to 1/4' washout. The SE has a longish nose so right thrust doesn't need to be much. The right thrust is only needed for take-off or sudden burst of power, as you well know. I don't wanna 'preach to the choir'!

I thought there was a warp as well,but couldn't really tell on my screen. But something i just noticed. Your prop nut is down and to the left of your datum line. The datum line appears centered, so that mean you have left thrust in the engine. Might just check that as well, while you're at it.....

sp

Thanks for all the possible things to consider. As or the engine, it looks to my eye as if it's 0-0. I think the nut being off-center in the photo is more about camera/lens alignment. But I'll check it out.

The problem with the way I've done the rigging (using fixed 0.6mm music wires) is that they can't be "loosened." They just have to be replaced. And replacing one usually means replacing several.

My main concern was whether the first or the second photo represents the "true reality" for the model. If the first is "true" then there is hugely more dihedral on one side than the other, and the elevator is out of alignment. If the second photo is "true" then the model should only need minor tweaking.

Here's a larger version of the photo (click on the thumbnail, then click again on the image to view the full-size image). In this photo I've adjusted the view so that the fuselage sides are vertical as a reference point.

I have to say you have a gut of iron to keep doing your maidens.
The wing has a twist, pretty obvious. My TF SE5a has a twisted wing and it flies OK. My question is how much throw do you have? How much can you push the controls back when deflected? I can push the ailerons quite a bit on mine. It makes it a handful. I fly more with rudder and use the ailerons as a wing leveler. Mine is not aerobatic because of that. I can get about a 1" of movement and I can push them back 3/8". Because of that they have a centering problem too that is the handful part. It is what it is. I ended building some new wing wires with parkflier clevises so I could have some adjustment. Mine likes a lot of nose weight even though I could fly it tailheavy and did for a couple of years.

Just correct it with trim and fly it. You know it pulls, or rolls to the left. Either put some right rudder, eight aileron, or right thrust in it and fly again. If it improves, then keep trimmimg. If not start over. Fly it, see what it needs and do it.

Is it obvious? I'm not seeing it. Top wing, bottom wing, right or bottom? In the photo the upper-left wing panel looks a bit different at the end, but upon closer inspection (of the photo) I realized that's because that aileron was slightly up when I took the photo (and you don't see the elevated lower aileron because of the angle).

For an actually twist, can you point out where? Of course, I'll also get out my incidence meter and remeasure. And, yes, the model was designed to have a degree or so of washout.

As far as "remaidens" go, one advantage of having it sit in my "hanger" for so long is that I've sort of stopped caring about it (so much).

It looks to me that if the fuselage is indeed level, that the upper wing has positive incidence and the lower is
at "0" or negative. The left lower wing has a twist in it, the leading edge appears low. My nickels worth :)

Great looking model

Just to make sure we're all using the same orientation, let's assume L and R relative to the pilot's view. So in this front view, the wings on the left are actually the right wings, etc.

A rear view would be very helpful. I would take a very close look at the engine thrust line. Is there a difference in trim with the power off?

Here are a couple more photos. (Sorry, I forgot to do a rear view.) This time the front view was taken from a slightly lower angle to show the underside of the bottom wing as well. Also I made sure the prop nut was dead center. For the side view, I propped the tail up so that the engine measured 0˚ degrees. The lens perspective distorts just a little but both the prop and the rudder TE are perpendicular.

Based on these new photos, it appears there is some degree of twist to the lower-left wing panel, i.e. it appears to have more washout than the other side. Also in this photo, I didn't rotate the image at all. The fuselage, UC, and rudder appear to be almost perfectly square. However, relative to those, the tips of the left wing panels (both top and bottom) are higher than the tips on the right. And the top center-section is visibly off.

Given these particular observations, would that account for the strong left-pull?

I don't recall at the moment the incidences designed into the model. I just built it the way it was designed. But yes the top wing is definitely positive relative to both the bottom wing and the engine thrust line. The elevator also appears to be positive.

And here's a side view with the stab/elevator propped up to 0, which then gives +2 on the top wing incidence. The stab looks to be about +3 relative to the engine thrust line (i.e. when the stab is level the engine is at -3).

And here's the report on the second flight:

http://www.rcgroups.com/forums/showt...363887&page=74


Here's a link to the page on the RC Groups thread where I document the incidence angles on the wings.

5.0_______________5.0_____5.5_______________5.5

4.0_______________5.0_____5.0_______________4.0


http://www.rcgroups.com/forums/showthread.php?t=1363887&page=72

Abufletcher- put some straight sticks chordwise on bottom of wings at the outer and inner strut locations for reference. Now, block your fuse so that the cabane reference sticks are the same height at front and rear. Measure the outer ones. You will find your problem that way. Your wires are non-adjustable but that is just gonna have to change at least once... right? lol Otherwise you are going to have a 'dog' of an airplane. You will only have to change the rigging for one wing at minimum. Too bad we don't live close by for I like rigging! I even build ships-in-bottles and models of sailing ships to prove it!

I tried that "stick" trick with the Snipe but I didn't trust that the sticks were really straight. Maybe I can try it again with some CF tubes I now have.

Greetings Abu,
Yes, all references to right and left are from the pilot position.

When I setup an aircraft I begin with leveling the fuselage to "0". That would be your top longeron to "0" degrees.

Engine thrust line is "0" if the firewall was glued in perfectly straight. Typically no more than 2 degress down
and right thrust is used ( if called for in the plans)

Wing incidence is typically "0" on the bottom and +2 degrees on the top wing.

Horizontal stab "0" or +1-2 degrees. (That is, leading edge higher than trailing edge)

I think your largest issue is the twist in the wing. Also, I didn't notice but if it's electric power
torque of the motor would possibly give you some problems, add power slowly.

I have never seen any more than 3 degrees incidence on any set of plans over a 30 year
modeling career.

You will get it worked out, just keep at it. Its a beautiful model.