Sandmann_AU

Yeah, what Yakflyer said. The horns go as close to the centre of the aileron as possible, the control rods come off at at 90 degrees to the hinge-line, and the covers go on whichever way they need to suit. From memory the servos were mounted with the control arms closest the fuselage, but don't quote me on that. Given the length of the ailerons it doesn't really matter which way they go, as long as you do the opposite on the other wing so you don't get spoilers/flaps instead of ailerons.

Matt-in-the-hat

Hey There All you Fellow DA owners. This thread has been a wealth of Information for me, I only wish I could Say I;ve read all 36 pages. I got through about 24 of them and learned ALOT, but I have a couple of questions that I would love some help on if you can.

First of all I Have 2 flights on my DA. and at 105mm cg she still seems awfully nose heavy to me, but after reading this forum, I have a feeling I have a very different issue than CG

here is my problem: She I have a lot of down elevator trimmed into her to keep her from diving at 1/2 throttle. I have it set up now so when I fly a 1/2 she flys straight hands off.
as soon as I throttle up.. at that trim setting she climbs ALOT. bring her back to 1/2 and shes fine again, and when I drop the throttle for approach the nose falls like there is a brick in it. So my feeling was.. nose heavy.. bring the CG back another 5-10mm.

then I read this thread and saw a post about wing incidence and wooden washers.... hmmmm

I bought this arf 3 years ago.. and only just assembled it this year... and I HAVE NO IDEA WHERE THE MANUAL IS. and further more.. I have these Wooden washers that I had NO IDEA WHAT TO DO WITH when I built it. they are still in the box. so here I am thinking after reading the post about setting the wing incidence, and using the wooden washers to do this, that maybe my climbing and diving issue is wing incidence related. I;ve never needed wooden washers on a wing before.. of course most of the ARFs i;ve built have used Dowels along with wing bolts so I suspect that is why..

Can anone fill me in on this washer thing.. and what I am supposed to do with them? and how I properly set the wing incidence?
any help would be appreciated.

kiosk

My Feedback: (14)

i dont believe the incidence thing with washers but to check decalage, try (with caution) to put her into a vertical dive, if incidence is wrong she will climb assuming elevator is neutral of course....usually this issue is to do with engine thrust angle needs adjusting, by giving some more down thrust putting washers/spacers in two upper bolts between firewall and mount....


here is a good reference trim chart which is very helpful....good luck

jrf

My Feedback: (551)

Could be wing incidence, could be engine thrust lines, but with the elevator trimmed down, it is not CG. If it were nose heavy it would require up elevator trim. It sounds like you have too much positive incidence in the wing and/or not enough down thrust in the engines.

As far as the washers go, they are intended to fine tune the wing incidence. Install the wings with the washers on the bolts and the bolts just finger tight. Measure and set the incidence of each wing so that it is as far "trailing-edge-up" as possible and both of them are the same. Then drip thin CA behind the washers to hold them in position.

If that doesn't do it, put a (metal) washer on the top two engine mount screws between the mount and the firewall.

You will alway get a little bit of nose down when you slow down and nose up when you accelerate, but it should not be "like a brick".

Jim

Matt-in-the-hat

maybe I am using the term wrong. when I say "down evelvator" I mean.. the trim. I move the trim downwards.. like pulling the stick towards me as in pulling out of a dive. .. the elveators themselves move up. maybe I am using the term wrong.

as for the washers. I will do this next chance I get. just to clarify the procedure. I will take the washer, and put the wing bolt through it like any other washer on a bolt. then screw it into the wing finger tight. then, I will push the back of the wings all the way up as much as they can go and tighten the washers. then I will measure from the bottom of the fuse to the trailing edge to make sure they are both the same, and then glue the washers in place. sounds simple enough.

I will try that first. and fly it. if that does not work, I will add a washer to the top 2 engine mount bolts on each engine to add down thrust. and try again.

thanks so much for your help.

as a side note, she is a really fun plane to fly. I look forward to getting her tweaked out and set up perfect.

thanks!

Matt-in-the-hat

as a side note.. without significant elevator trim she will ALWAYS dive. even at full throttle when the elevator is nutral. when I trim it about 3/4 of my elevator trim I can keep her at level flight at 1/2 throttle. then at that trim setting when I throttle up, she climbs almost like she is going for a loop. then when I drop it to idle. she will immedatly dive to about 50 degrees down. and I half to hold about 3/4 elevator to get her to come in and land nice.

thats why I thought it might be nose heavy... but hopefully the wing incidence will fix it.

thanks again

JoeMamma

The pre-drilled wing-to-fuse mounting holes were off a mile on mine. About a quarter of an inch difference from what I remember.

I redrilled the holes, lifted up the trailing edge of each wing so they were dead-on even, installed the wood washers, tightened up the wing mounting bolts then dripped in some CA to the wood washers. Just be extremely cautious not to drip any CA into the wing mounting bolts. LIKE I DID !!

I also agree with jrf. Try shimming the upper part of the engine mount to get the engine thrust line down about 1 degree.

I have mine nose-heavy at 100mm, but when landing I can flair it in with the nose up about 20-30 degrees. Go figure ?? Seems like mine's tail-heavy at 100mm ???

Joe M.

Sandmann_AU

Heya Matt... from another Matt...

Just a couple of thoughts here...

- Set your wing incidence the way it's been suggested but only add ONE drop of CA... then fly it to see how it is (don't forget to tighten the bolts all the way first). If it's not quite right you can break off that one drop but if you flood it with CA you'll never get the wooden washers off.

- Make sure both wings have the SAME incidence or you'll be messing with aileron trim later on to stop it rolling.

- Smear a little vaseline on the wing bolts before splashing that CA around so they don't get glued in place too.

- Don't go messing with the down thrust till you've set the incidence. Unlike a single engine plane changing the incidence will also change the thrust. Whenever you're trouble-shooting (not just planes, ANYTHING) only change one thing at a time.

- If you do end up having to change the down thrust DON'T use metal washers - after a couple of flights they'll get compressed into the wooden firewall and you'll be back where you started plus you'll have loose firewall mounting bolts as well. Your local hobby shop should be able to sell you some very thin light ply, use a strip of that instead and CA or epoxy it into place once you're satisfied it's right. Don't use balsa, it's too soft.

- Pulling the elevator trim towards you is called "up elevator", as it angles the elevators are up, which also pulls the plane up.

Good luck with it... let us know how it turns out.

Yakflyer

My Feedback: (2)

There are some good response for you listed for your question. But I can't help but think you maybe experiencing the same type of DOH moment I did.
When you set your CG, did you place the DA upside down and then set your CG? If you set the DA right side up, you will have the problem your describing. (I did, so your not alone)
Once I set the CG on DA while 'upside down' on the CG machine I found a different CG all together. Out of personal choice, I set my CG at the backside of the range and I do not have any trim adjustments needed to enjoy level flight from 1/2 throtle to full throtle.

I agree with the early post, the wooden washers were used for the wing bolts.

Here is a online manual if you still need one.
http://www.horizonhobby.com/ProdInfo...025_manual.pdf

I think your CG is too far forward, it could be a thrust line issue, but my gut thinks your CG just needs a little corrction. The manual calls for 80-90 mm from leading edge. I put mine at 100 to counter the engine wieght. Besides, it sets the plane up for some very cool looking powered flat spins that almost hold altitude!

Hope you can find some useful info!

jrf

My Feedback: (551)

Matt: WAIT. The advice I gave you is backward because it was based on elevator down-trim, and what you have is elevator up-trim. You need to raise the leading edge of the wing, not the trailing edge.

But back to the original question; with that up-trim, it does sound like the airplane is nose heavy. To review the basics, you balance the airplane upside-down and level on the balancer, ready to fly, but with the tanks empty of fuel. Make sure that CG is right before you do anything else.

Using the wood washers to even up the wings is still a good idea, and it won't make much of a change, so go ahead and do that. Recheck the CG and then test fly it again before you add the down-thrust.

Jim

Matt-in-the-hat

yup I did check the CG inverted. Now I don;t have a sophisticated cg measuring device. I used my fingers. not the most accurate, but it has always worked for me in the past to get a ballpark cg. it is at approx 105mm + or - 5mm due to my fingers.

Matt-in-the-hat

OK THANKS JIM. sounds good,

So if I understand you right, I need to do the washer thing, only this time raise the leading edge to the max with both wings. check that they are the same distance from the fuse, and then CA the wooden washer in and re-test. sounds easy enough.

I will do that first, if that does not work, then I will move the battery back a few inches to rebalance and try again.

thanks again everyone for your help.

Yakflyer

My Feedback: (2)

Keep us posted on your progress. Your question has me curious what your issue is to learn from.
Good luck!

jrf

My Feedback: (551)

Yes, you have it right.
Jim

Matt-in-the-hat

Will do. Likely won;t be able to make the changes and test though for a week or 2 lots going on at work, but I will most definatly let you guys know how it turns out.

even with all the issues I had on first 2 flights, the plane still flew awesome and sounded great! so I canèt wait to get it running perfect!

Lefte

My Feedback: (1)

Vasaline to block the CA...never thought about that one..Good job Matt.

My DA had a new manual that had tape over the CG and placed it at 100 to 105mm...

Lefte

Matt-in-the-hat

So I worked on the Dual Ace, and saw that there really was very little "play" in the wing incidence so I kinda ruled that out right away. I moved the Battery back about 3 inches and it flew ALOT better. Did 5 flights on it and I found it flew a hair nose heavy at take off, within a minute or two of flight and trimming it was fine, and then by about 9-10 minutes of flying it started to get a litte tail heavy, but It seemed to be a good genral CG and it landed fine while it was a little tail heavy so I'm fine with that.

unfortunatly on Flight number 7, I was getting more comfortable with the plane, and I decided to do some high speed passes. Up until this point was only ever flying it at around 3/5ths throttle. which it performs nicely at.

so I did one nice low high speed pass and it looked great. and seemed to perform well. I came around and did another, and then another to get the hang of it. I am only using 10x6 props so it only really hits 60mph, but still looks great.

on the 3rd pass, one of the ailerons flew off and was dragging by the push rod. the plane immetatly started to roll towards the dragging ailron. I immedtatly throttled back, assuming it was caused by engine flutter, and kicked in high rates trying to compensate with both ailron and rudder, but she was fairly close to the ground at that point.. probably less that 50 feet, and she just spiraled in towards the fallen ailron.

In hind sight, I probably should have kepted the power on, to keep more air moiving over the good ailron, and re-gained control at a faster speed get used to it and then land it at a fast speed, but, I only had about 3 seconds.. and all my previous experience with these types of issues told me it was flutter and to throttle back. after looking at the crash damage the engines seemed fine so i'm pretty sure it wasn;t flutter. , and all 3 hinges on the one side were shered. they haddnt pulled out, they just were all ripped in half. I've never seen that.

Anyways. its not re-buildable, and at $200 for the ARF it would be stupid to re-build it anyways as it would likely cost more. I'm not sure if I will buy another one. seems althoght this is a fun plane, this ARF might be a little on the cheap side. (quality wise) might be a good idea for me to find a twin of a little higer quality. If anyone has suggestions of another .46 sized arf let me know I;ve already. got all the gear I need.

JoeMamma

Matt,

Sorry to hear about your loss.

Without seeing your EXACT procedures when installing your CA hinges, it's very difficult to comment on why they just sheared off. I've seen my share of CA hinges pull loose, but this was usually due to a builder error.

The hinges MAY have sheared off from flutter, but again, it's very difficult to comment without seeing your EXACT aileron setup including hinge-gap dimension, actual CA application, depth setting of each hinge, type of control arms, insufficient servo size, or sloppy control arm links at either the aileron or servo ends. Flutter is usually caused by one or more of these items.

You mentioned kit quality. I've seen some real stinkers out there in "ARF" land, but I thought the quality of mine was much better than average.

In my opinion, I'd would break down and get another Dual Ace.

Joe M.

boingram

Got over 100 flights on mine and still in good shape...a little ragged, but still airworthy. I have seen several Seagull kits and they look pretty good...hate to say it...but probably builder error...Bo

Yakflyer

My Feedback: (2)

Dude, that's terrible! At least you were able to get 6 knee knocking flights of enjoyment. Still it is terrible that it crashed.
I guess I should have mentioned it early, but when I started this model and the fact I was/am going for all out speed, flutter was an item I addressed while building.
After making sure the hinges were firmly in place with minimal gapping, I went a step further and added some monokote over the hinged area to help keep that issue from being a problem. Maybe you might use that tip on your next model. But there it is. Some have even swapped to pinned hings and epoxy for that extra holding power.
BTW, watch Ebay regularly for the DA. I got mine, with shipping for under $100.
There are plenty of good deals on ebay.
I flew my DA at Hodges Hobbies this past Saturday. I almost left with another twin engine plane. Not sure were you live, but there is a Top Flight 310, fully completed ARF, with no flight pack or engines with ROBART RETRACTS alread installed along with a complete nav light kit for $400. That version used the fiberglass one piece body. It was 'VERY" attractive.
My first dual engine was the Cider Hobbies dual ugly stick. You can find them pretty inexpensive. That would do a flat spin and hold/gain altitude! It was crazy watching that but fun to fly!
Good Luck on your next project!

boingram

Yakflyer....I love the Cedar Hobbies Twin Stik, but can't find another one...any ideas.....thanks...Bo

Matt-in-the-hat

WEll if its builder error, I'd love to know what I did wrong to prevent it. I've never seen flutter in a model before except in my Katana, when I picked up a piece of gravel on take off.. (never doing gravel runway again) and it cracked the propeller and threw the engine out of balance.

I am certian I had no slop in the linkage. someone else mentioned an insufficent servo could cause flutter? what servos are you guys using? maybe it was builder error in the sense that I selected insufficient servos.

boingram

I am using 60oz digitals. The ailerons are not that big on the DA and while it's a fairly fast airframe, I would look more toward an improperly installed CA hinge....just can't see flutter if your hinge gap was not large. Did you do a pull test before the flight?

BTW...be sure to brace the long rudder pushrod.

Bo

Matt-in-the-hat

WEll I ordered another D.A. today. the airframe is cheap enough so I will try again. I will go to epoxy'd pined hinges this time as per your suggestion. have used CA hinges in all my models thus far, but maybe on this one pined hinges are the way to go. When you do the monokote on the hinge gap.. do you do it on the bottom of the wing or the top? or both?
any other tips to help reduce this on DA #2?

also,, if there are any other concerns you think I should change.. now is the time, as I will likely recieve the new one and start building early next week.

Any way you think the motor mounts could cause flutter? they did look kind of cheap to me.. think they might be causing vibration? think it is worthwhile switching them out?

Matt-in-the-hat

No I did not do a pull test before the flight. however I did check them 30 mins earlier before the 1st flight of the day and they were fine. but that was the 3rd flight of the day.