orthobird

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i would like to make a clarification:

i got the incidence meter

and with me going thru the steps you described for washout,

i see if i am standing on left side of plane, and the meter faces me, when i tilt it down on leading edge the number on meter becomes more positive

if i go from 0 at root to measure at tip, and going down with meter at leading edge, the number is positive, which really means negative. so the measurements i gave you all first were reversed, thank you for helping me understand this and to use the meter.

i have learned if you are standing on left side of wing, the meter will be reverse, compared to right side of bird.

so, i have in reality, on left wing, -1.0 degrees incidence change root to tip

and right wing is same thing

so both wing tips leading edge are less than one degree lower than compared to root area.

orthobird

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UPDATE on new balance

here are pics after i moved all servos anterior as possible.

now i am using 9 ounces less in nose and this is what it looks like:

da Rock

Looks good.

Over a half pound lighter? [sm=thumbs_up.gif]

otrcman

Yes, the attitude of the plane looks much better now. Hanging the model from "above" to check CG really does mask the measurement a lot. If the plane is somewhat tail-heavy all you see is that it hangs slightly tail low. If you were to hang the model upside down you would find it much more difficult to balance, but your measurement would be very accurate.

Dick

orthobird

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hi Dick,
thanks
i was unaware of this,
please enlighten me,

so i should balance the plane upside down?

what is i did is i put a wood screw in bothe wing tips at the CG point,

and use this to suspend plane with small diameter ropes.

is this technique not good enough?
i should do the same with plane upside down??

also

i have made a grave error, and this is, i did not follow plans completely, ie,
during final stages of build, it claled for struts to be used to help with washout, and that i was to adjust it so that there would be 2 degrees at tip from root of wing.

earlier in thread, i had posted on the first flight and how awful the bird flew, tail heavy and all, which i believe i have improved, and the roll issue.

then i made all these measurements, of the incidence , at root, at tips, and with one wing comared to other
and i had (mistakeably) made some conclusions,

but yesterday, i realized that all the measurements were done with struts off

and that, i actually never paid attention to this prior to maiden flight,

my mistake,

it appears i can manipulate these strust to get the washout and equality of incidience of one wing to other

any thoughts?>


thanks again,

rmh

Balance as you were - that is fine
-no fuel on board.
the wings -I doubt you can easily twist but if possible keep em straifght on perhaps the leading edge at tip a tiny bit lower . that wing design is not critical.

Roguedog

csh

I would wait to fly this bird until you get a different incidence meter and recheck the angles.

I wanted to let you know that the Hanger 9 AnglePros are a piece of crap and don't read correctly. If dropped more that a 1 ft above a surface they go out of calibration. I called tech support on what to do as I tried the calibration procedure to no avail. They could not help me out and said I needed a perfectly flat surface to do the calibration.Since I waited to long to try them out I couldn't get my money back on the 2 that I bought. $145.

A quick way to see if there out of calibration is to set the jig up on one side of the wing take a measurement than reverse the AnglePro at the same location. Mine where off as much as 1.5 degrees. I never got an equal reading. Junk in my opinion. If youcan get your money back do it asap.

If you can find a Robart incidence meter I would use it instead or something else a least with a jeweled meter.

That being said I wanted to recommend that It would be better to fly it with the CG a little forward at first andthen adjust using a flight trimming chart like the one below. Aslo it appears the -3.5 degree stab incidence must be to help keep you from nose diving the plane before it gets to flight speed IMO. I can't imagine any other reason to have so much negative incidence on the stab.

But again, sinceI believe yourHanger9 AngleProsaren't reading rightall this is a moot until you can verify for sure your getting the correct measurements from them.


Regards
Bryan

orthobird

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wow

i just saw this now

i was coming here to give you all an update.


i did make adjustements based on this meter, and i wish now that i had read this before today.

run down:

in past few weeks, i was able to move all servos, radio equipment, etc... as far forward as possible.

i re did CG, so it is more anterior.

i used the incidence meter, and felt that the right wing had increased incidence relative to the left wing, so i made an adjustment whereby the fuselage seat for the wing on the right would be higher on right side, to make incidence more even with both wings, which it was, based in incidence meter.

so, today, went to field,

cranked the Saito FG 36, beautiful sound.

warmed it up, revved it up, going strong, turning 18 X 8 master airscrew prop 7900 rpm.


then, got it on runway, and plane took off, no problems.


immediately, i noticed plane was flying much better than first flight, and it was not tail heavy any longer.

however, as i flew it, i t had a tendency to roll to the left.


i was basically flying plane with right aileron, to keep plane level.

i tried to trim aileron and rudder, but nothing worked

i just brought plane home, had a bit of a rough landing, and ripped landing gear off.

no damage to wings, tail, or nose.

this can be fixed easily,

however, i am still perplexed as to unusual flight characteristics of this plane.

it wants to roll to left.

any advice.


right now, i am feeling to glue landing gear on, and hang plane from my garage, since it is pretty to look at.

Roguedog

csh-r,
I went through your thread again to make sure Ihad a good understanding of your problem. I wondered if by chance you did a lateral balance to see if one wing might be heavier (left) then the other (right). This could contribute to the problem. Have you had a chance to reverse the meter in the same location to see if the readings are different? Until you're are sure about the accuracy of the Angle Pro all the incidence data is questionable. I would do as many static measurements as possible as far as the wing is parallel to the stab and perpendicular to the fuse. etc.

I would also check the engine thrust to make sure it's at the static starting point, not enough right thrustcould contribute to left rolling.

Next I would use your angle pro and measure the left wing twice as close to the root cord as possible write down thatfigure. Thenreverse the angle pro so that the LCDfaces the opposite direction. Compare that measurements. If one figure is negativeand one figure is positive this is the error showing up in the meter.

Example -if the incidence is +1.5 one way and -1.5 the other, then angle pro is off 3 degrees. Nowdo the same for the tip cord on the left wing. Repeat for the right wing. It's a PINA but you can use this method to at leastgetthe incidence close enough so that you can flight test the plane with the chart I posted above to finish triming the plane with the flight test results.

Another thing thatcould cause left rolling is to muchwashout in the left wing. Out of ideas.

best of luck,

orthobird

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hello,
thank you so much.

i believe the wing may not have been the problem at all.

let me tell you what i did today. i could not sleep all last night, thinking that possibly there was an error on my behalf when i built the airplane and placement of the fin. I also thought, why does plane keep rolling to left when i flew it, however, aileron trim did not help and rudder trim to right did not help either.

so this morning, i tool a lightweight 4 foot long builders ruler and balance (in one), and placed the ruler parallel to fin on left side of it, and near to wing bay, forward to wing, i noticed that it was ligning up on a point to the left of the midline of forward fuselage by about 25 mm.

that means that the fin leading edge is heading towards left side of airplane, and when thrust, which is aimed to right by 3 degrees, this air pressure (thrust/wind from motor) is greater on right side of fin instead of equally distributed on both right and left side. this turbulent air flow on the fin, which has a higher pressure on right side of "twisted" fin, and causes the plane to roll to left.

at least, this is my theory.

i carefully cut the coverite on the right and left side of fin base, and using a flexible thin saw blade, i detached the leading aspect of fin from fuselage all the way to rear except for the trailing 1 inch of it.

i then used a laser light, and attached to a flat ply wood, placed it on side of fin so that laser light was in front of fin, then slowly moved fin to the right until light was in center of fuselage and in line with propeller blade, which i placed upright and i also used the level which hung from prop hub.

i reglued it.

let's see what happens.

Roguedog

I believe the thrust vortex places air pressure on the left side of the fin in a clockwise fashion instead of the right side. Unless your engine rotates counterclockwise .

If the vertical stabs LE was left of center with regards to it's TE thenthis would cause yaw or rolling to the right, not to the left. Centering the verticle stab(fin), will now cause an increase in the left rollproblem if I am reading your post right. Check your right thrust again.

Attached pic is a quote from a series ofarticles Dean Pappas wrote for Model Aviation magazine called Timming for the Gound Up.The three articles numbered 29,30, and 31 are about trimmingHere's the linku will have to use your AMA # to log in.

http://www.modelaircraft.org/mag/ftg...29/29main.htmlgoto the FTGUIndex http://www.modelaircraft.org/mag/ftg...espageftgu.htm to find the other two trim artcles

orthobird

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Wow
This makes sense

Tell me wha you think of this

The engine is an saito fg 36
That came with its own engine mount
The engine is not upright or inverted
Instead the cylinder head is out to right

When I built the plane
The firewall had built in 3 degrees right thrust and 1 degree down thrust

Roguedog

I would get that level ortape measure andcheck the 3 degrees right thrust again just to besure. Unless the Saito's motor mount has some weird built-inthrust this all sounds great, but it doesn't solve your problem as I see it. If straighening out the verticle stab solves the problem great, but I would be prepared for a harder roll to the left after take-off just in case.

Although it was alot smaller, I once had a foam cessena that had such a bad warp in the wing to the right it was unflyable, well at least for more than 10 seconds. Could not get it leveled out would roll right overinto the ground. A few years back I purchased a prebuilt Kaos that had -4 degrees downthrust +3 degrees of incidence and both the verticle and horizontal stab were tilted downto the left with the right stab back 1/2 inch. That first flight was fun. After flight trimmingand corrections,around 50flights,it tracks very well now.

orthobird

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hello. this was this birds 3rd flight, and by far, the best yet. but to me, still not good.
1st flight: plane took off no problem, i immediately noticed it wanted to keep climbing, at the time, i was unaware, but the bird was flying way tail heavy. the way i checked CG , by suspending plane from wing tips at CG point, was way misleading. I then trimmed elevators, to help with flight, but this was not much. when i could get plane to fly level, by holding elevator stick up, then once plane in semi level flight, it would immediately roll to left. soon after that, very quickly, i said, this is not fun, this is not the way to fly. believe it or not, i was able to land the plane, only damage was the landing gear bent on one side. this was fixed easily.
2nd flight: i addressed CG issue, i added about 16 ounces of weight to nose, and i shifted all servos and batteries as far forward as i could. this time, plane took off, did not appear to be tail heavy, this was improved flight pattern from before, however, plane kept wanting to roll left. i also had made a change to the plane prior to second flight, whereby, i made trailing side of right wing sit 5 mm higher on right side of wing bay saddle area, using incidence meter, now both wing roots were even. i still was not satisfied with this flight pattern.
3rd flight: i redid the fin, so that LE was not to left of TE. i believe the fin is well centered this time. this flight was best of all, however, plane did want to roll left. trim did not help much. prior to this flight, i did a CG check, and plane was neutral, i also checked side to side balance. i placed a string under a low hinge on rudder, and tied another string on prop hub, my wife and i then elevated plane off table in a room with no wind or breeze. i was thinking that possibly left wing would be heavier, but to my surprise, it was the right wing which was heavier??? i then added 1.5 ounces of weight to left wing tip. this leveled it out side to side. the flight, again, plane kept wanted to roll left. i am still not satisfied with this bird. i am now going to put all batteries under gas tank, and remove added weight, hoping to balance it this way. i may be able to get rid of 12 ounces of extra weight. that will make plane 18 .5 pounds, better than almost 20 pounds it was at first.

i need to make a correction. the Dynaflite super decathlon build is for 2 degrees right engine thrust and 5 degrees downthrust.
the incidence is -3.5 from stab and -2 from wing.

i believe my plane has +3 degrees incidence wing relative to stab.

the thrust is: +3 degrees to right., downthrust is +2.5 degrees

thank you for the advice and guidance.

do you think i should add more thrust to right and down?

Roguedog

Ok if I'm following you here, Here's what I am thinking;
Downthrust is off by a huge amount.
I checked the Dynaflight technical specs and it recommennds 5 degrees downthrust that would be -5 degrees. If your plane has +2.5 your 7.5 degrees off. I'd leave the 3 degrees right alone for now.

For the incidence if your plane has +3 relative to the stab that's +1 degree wingincidence which makes the wing incidence 3 degress off. according to the tech data it should be -2.

Until these anomaliesare verified and fixed to there static values you're not going to be able to get and handleon the left roll/yaw problem. These two out of spec adjustments maybe making the planeunstable enough to cause the problem in the first place. Fixing these two issues may be the solution.

My Kaos wing happens to be heavy on the right wing by .75oz. Problem is when I add the required weight to the left wing to balance it laterally, the left wing stalls horribly when entering a loop and then does corkscrew loops. I removed the weights and it tracks fairly straight though the loop with the right wing heavy. Go figure. I'd remove the weights on yours as well at least until u fighure it out left yaw/roll problem..

Bryan

orthobird

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hello

i got my Robart incidence meter, after your recommendation
and you were right.

both wings have exactly one degree of washout.
the only difference is that the right wing root has one degree more incidence relative to the left wing root.

should i worry about this.

would this account for bird wanting to roll to left?

orthobird

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check this out

otrcman

The resolution on the video isn't quite good enough to be sure, but it looks like you started your takeoff roll holding full up elevator. Do you know if you ever released the up elevator ? It also looks like the plane came off the ground still 3-point. That's another indication that you were holding a lot of back stick. If so, then the airplane simply stalled as it broke ground. Notice how steeply it pitches up immediately after liftoff. And notice how the airplane yaws right in addition to rolling right. Those are all classic indications of a stall.

The greater incidence of the right wing panel would normally try to make the plane roll left. But if you stalled it at the moment of liftoff then the plane would roll right, as it definitely did.

Keeping the stick back for the initial takeoff roll is very common technique to maintain better heading control. But keeping the stick back at too high a speed is deadly. If you are heading into an 11 mph wind, then you probably don't need to hold the stick back at all. The airplane will head into the wind naturally.

Dick

Roguedog

cshahrdar,

Ouch!

I have to agree with otrcman about the elevator. It appears you had full up elevator and never let the tail come of the ground and due to this immediately stalled the airplane as it attained flight speed. I also agree with his analyse about the right wing stalling first due to its' angle of attack being +1 more than the left wing. This would cause the right to stall before the left. Also this goes for it pulling to the left when you did have it flying the other times as well. The +1 degree more on the right wing would cause the right wing to lift more than the left when flying.

I'm not happy with those damn Hanger 9 Angle Pros I bought. Just junk IMO. I thinkthey should pull them or issue some kind of statement that they are having problems with the design. I wonder how may other have purchased one and crashed their plane becuase it doesn't work as advertised.

You mentioned you already repaired the damage. I hope it was minimal.

Regards

Bryan

orthobird

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Update:

rctech2k7

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Good update... I have the same point with otrcman comment. Aircraft hasn't build enough airspeed yet and too much angle of attack on takeoff. If the cg was located forward it might save the aircraft from accelerated rotation and the airborne speed is above the stall speed of the wings, however it may not be advantage to the flight of this aircraft... Reducing weight is a correct solution or increasing takeoff speed.

da Rock

Look at the video again. It appears the elevator was being held full up all the way to when the main gear lifted off. The plane most certainly left the ground before rotating to the horizontal, which is what tail dragger models should do (rotate to horizontal) on a normal take off with a neutral elevator position. Which way were you facing in that video?

The problem on that takeoff really doesn't look like an aerodynamic problem. Tail draggers already sit with the wing being presented at a stalled AOA. The tail has to at least start to rotate to get the wing out of a stalled AOA. The wing is going to lift even when stalled. Too much power too soon usually keeps the wing stalled yet pulls the model into the air.

In any case, holding the tail down with elevator on that takeoff was not a good idea. Tail draggers are like any other model. They need to be relatively horizontal before taking off and that never had a chance to get there.

Roll the throttle in gently and get off the elevator sooner.

otrcman

All right ! Looks like you can fly the airplane long enough now to observe the details and figure out what to do next. Your plan to increase right thrust sounds like a good one. One other thing you might be able to do (providing you have a programmable transmitter) is to mix in some right rudder with throttle. That is, you would like to have the rudder move right a tiny bit as you increase throttle.

The other thing you might consider on you next flight is to trim out any rolling tendency with rudder rather than with aileron. I know that sounds counterintuitive, but it is the correct thing to do with a high wing airplane, especially if it has much wing dihedral at all.

Dick

orthobird

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Ok

orthobird

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update