tmark65

Papaone,

In another thread about Abbra (http://www.rcuniverse.com/forum/m_22...y_Abbra/tm.htm) post #94, you say that a friend wants to buy your Cocaine .... !!!!

Did you finally sell it ????????????????????????????????????????????

Are you still thinking of selling it ???????

I'm interested !!!

papaone

Hello Tmark65
Yes my friend bought my Cocaine. He 's going to modify it in seaplane
to do seaplane europeen contest.
Regards

PATTERNPATTERN

Hello,

Its time to bring this thread back to life as I need your help.

I couldn't get my Imact flying right, The main reason is I rushed the building and didn't align it right.

I have now stripped back the model to set it back up with the aim to getting it flying right. I have it set up with a hacker c50. This time I am going to use wing and tail adjusters. And use the origional rudder and not my own balsa one.

So my question for you guy's who have being experimenting is what is the best settings for the following also maybe you can comment on why you are suggesting these settings:

1. Wing incidence

2. Tail incidence

3. CG

4. Engine Thrust

Also what is the best method to mount the composite arf rudder, I know there was some issues with CARF way of mounting it. I also want to mount ail servo in traditional method and use new contol horns. Any advice / pictures on these areas would be a great help


I would really appreciate your help on this matter, after all I am sure I can get this plane flying well, it won a us nationals and place high in European and World champs albeit in the hands of top German and USA pilots.

Thanks

Pete

Malcolm H

Wing Incidence - adjust to get the fuselage flying at the angle you like.

Tail Incidence - adjust to remove any elevator trim once you have set the CG and done your downthrust checks

CG - mine is on the rear of the wing tube and has a very very slight pull to the canopy in down lines

Engine thrust - My C50 is lined up with the nose ring

What are my incidences in absolute terms? Haven't a clue and don't care! In my opinion you are wasting time adjusting any of this before flying. Fly it then adjust to suit.

Malcolm

PATTERNPATTERN

Thanks Malcom,

Mine flew with its nose very high in level flight, does this mean that I need to raise the trailing edge of the tail to get the nose more level?

Did you use the markings on the fuz as the initial ref point?

Also did you find any twist in the wing or tracking issues in level flight?

Thanks,

Malcolm H

So did mine. To fix this you need to increase the wing incidence - i.e. raise the leading edge of the wing.

I think I required 1/2 a turn or so on one adjuster to get neutral roll trim with the ailerons level. This could be my slight error on initial setup rather than any warp in the wings.

I did start with both the wing and tail nominally on the marks.

No tracking issues and mine goes up pretty straight with the motor aligned to the nose ring.

Malcolm

PeterP

As a giude to what I have done as far as incidences these are some of my measurements.

with fuselage sitting in my jig the bottom of the fuse (lowest part just behind chin cowl is 2 mm above the surface of the bench. The tailpost is 47mm above the surface of the bench. At that point incidence was set to .25degreees positive on wing and zero on the tailplane. Then from here I dropped the rear of the tailplane by 2mm. I dont know what the relationship is now between wing and tailplane but I would guess between 0.1-0.2 degrees. The angle the fuselage presents to the horizon is extremely important and I cant stress that enough. You need to make sure that is correct as well instead of just looking at relativity between wing and tailplane. These setting are pretty close to the mark IMHO. By lifting the rear of thte fuse I in effect added more down thrust which it required.

Cheers,

Peter

PATTERNPATTERN

Any new updates on my alinement question from post #:728

stek79

Hello guys,
since you are speaking about trimming, perhaps I can ask a question.

Is there any test manouver to fly in order to spot an elevator mis-alignment problem? I mean some difference between the incidences of the two stabs - I don't own a good incidence meter, so I'm asking myself how to be sure that the two stabs are ok - during flight.

Do you find that a slight difference in incidence can be a problem during pushes and pulls? Of course, let's imagine that the stabs are correctly aligned with the wings (if we look at them from behind the airframe).

Thanks!!!!!!

f3a05

A simple static check is to tape a straight light balsa stick to each el. half at the same place on each one, pointing straight back, beyond the back of the rudder, and then balance a third stick on the two taped ones, at right angles to them, and about the same width as the stab.

Then you can sight from the front, and check alignment ,at neutral, and during movement from neutral to full deflection.
(invert the model to check down elevator).

stek79

Clever idea! Thank you f3a05.

But we could have the elevators aligned but the stab at different incidences...

f3a05

OK----Another low-tech method.....
Pin/tape long balsa sticks along the centreline of each stab tip(or along the elevator tips with these tips aligned with the stab halves, depending on the design)
The sticks must project behind the rudder.
Now stand well back to one side, and the sticks should be parallel to each other.
You can use the same method to check wing tip alignment.

Now ask what to do if the tips are curved in plan view!?

stek79

In fact my plane has them curved...

tggilkey

Another Impact flies! Mine went to a contest this weekend with 7 flights going into it. It felt comfortable enough from the first that I just decided to stay with it. It's the White/red version with trim painted using PPG Concept colors from Radio South. It's powered by a 160 DZ swinging a 17X12 APC prop. It came out right at 11 lbs. -- that could be trimmed down by replacing some pieces with lighter materials but it will probably stay where it is. The plane flies very nicely -- I set up the incidences as described earlier in this or one of the other two threads by using the 45mm difference between the bottom front of the fuselage (at the opening for the enigine cowl) and the tail. The post I copied used a 2 mm spacing between the table and the same front spot, and a 47 mm block under the tail. I just let my front touch the table and blocked the tail up 45mm; (re)set stab at 0 using the rear pins; initially set the wing at 0 to have a starting point -- then added what I think was 1/2 turn positive to each Gator adjuster (the adjusters are 6" either direction from the wing tube); and used the face of the fuselage spinner ring as reference for the engine placement. It has all the enhancements/improvements put in as described in the various postings -- mine was purchased before any of these were put in or included with the kit. The DEPS system was used for elevator control. The balsa tube/pushrod supports were tied in to the Depron foam "ladder." The ladder is glued to the front of the first brace that was recommended. The front of the ladder overlaps the tray for the rudder servo which was made big enough to carry forward of the TE of the wing. All done in an effort to minimize open places for stress to concentrate and flex/fracture the fuselage. A diagonal bulkhead was also added about 1/2" inch behind and parallel to the rear of the canopy opening. A vertical brace was added in the fin to stiffen the top of it -- placed somewhat aft of the point where the fin would go horizontal toward the hingeline. A new rudder was built from ribs and balsa sheeting (similar to another posting) -- the tailpost was also replaced with a conventional balsa post. The counter-balance was cut off the composite rudder and glued to the top of the fin (mostly to maintain the Impact look). At this point there seems to be enough rudder without it moving, also. Naturally the new rudder is lighter than the composite rudder. Using the wings-off method to balance it, I have started with the CG at the center of the wing tube -- the battery pack is right behind the wing tube. The one thing I have not done yet is to laterally balance it -- I remember there being a difference between the wing weights when I first got the box, but wanted to wait on that until after flying it some and to see how the airplane "sees" the wings. With the above setup I needed about 2 JR beeps of down and one or two of some aileron -- don't remember which way. On the first flight I was prepared for the worst with all the tales of a twisted wing panel, tails coming off, and who knows what else… The way it is set up does require a tiny amount of down elevator mixed with low throttle; and I don't have the Knife Edge mixing quite right yet -- but I can say that it won't take much in the end. It was not bad enough to cause problems for the limited amount of time we are in that attitude so it hasn't been a high prioity. Engine issues have consumed airplane time that might have been otherwise spent flying. Those seem to be in stage where I can get on to the busioness of tweaking the plane now.

Control throws were borrowed from postings and then cut down. The differential may have to be tweaked -- sometimes I think I see the airframe being displaced in the direction of the roll. Not sure… need more time on it… Not satisfied with the snap rolls -- this is not to say that it does not snap well -- it just means I don't have it set up so that it snaps the way I think it should.

The plane has shown me how much potential it has -- I just have to learn to use it now!

Yeah, it shrieks...

Many thanks to the many post-ers who solved problems and in several cases responded directly to my questions. Everyone's words and pictures helped enormously. It only took what seemed like forever to get it finished off because of other things jumping in ahead of it. I don't have a digital camera or I would post a picture of it (after I get the name put on it…..)

Good Flying to all!
Tom

PeterP

Hi Tom,

I think it was my settings you used to setup your incidences. Great to hear you are happy with it because I am still impressed with my model. Mine is still flying and it has probably done 250+ flights with a DZ160 up front. Mine came out at 4.65 Kg only because my kit was lighter than good building. There is a big variation in weights in kits as I have just bought another which is 150 grams heavier.

I fly the F3A sequences so the model has had quite a workout.

I have spent many hours trying to dial this model in because I am very fussy about having a well trimmed model.

From what you have said can I make the following suggestions which have improved my model enormously.

1. *****Important***** seal your ailerons and elevators (I have a successful method which I have posted elsewhere in this forum). Your snaps will improve 10 fold. I could not get a clean snap consistently until I did this.

2. CG wings off. Set it just behind the rear of the wing tube. Much less work in rolls especially on 45 degree up lines.

3. Aileron differential- 1mm more down than up at low rate. Not sure about high rate.

4. Mix 1-2% down elevator to low throttle.

5. Set thrust as per model. This should be perfect!. Mine climbs straight as - one of its strong traits which presents nice lines between maneuver segments.

Peter.

tggilkey

Hi Peter --

Thanks for the reply and information. It definitely was your settings I used -- I just didn't look "up" in the thread when I typed up my post...

I had decided not to seal the hingelines but have changed my mind on that -- the 10 fold snap improvement convinced me! I have seen (in the AMA Masters 45 deg downline) a pretty lousy snap if going too fast into the maneuver. Sometime ago I had purchased some sealing material from NorthEast Sailplane Products -- clear mylar with adhesive on half of one side -- it looks like what I just saw in one of your posts -- I'll definitely give that a try.

The CG change will be pretty easy to accomplish -- lots of room to move the battery aft. I've noticed that it droops more than I'd like or am used to after a roll or snap in a 45 deg line.

I'll check what I have right now for aileron differential -- what amounts of throw are you using? I think I mentioned in the posting that I was using less overall throw than some people's "low rates" -- things get too touchy for my taste even with a bunch of differential. What are your throws (especially on aileron)?

The down elevator to low throttle mix you mention is what I'm flying now.

What's your choice for props?

The straight lines and smooth pulls/pushes is what made me take it into a contest with only 7 flights on it and not really "finish-trimmed" on either plane or pilot... I've had what I thought were pretty good pattern planes in the past but this is a lot better.

Any further insight will be appreciated

Thanks, Tom

PeterP

Tom,

I will get some throws written down tonight.

I setup my aircraft very soft as well. I an pretty close to gating my controls on normal flight mode.

Props: I currently run a 16.5x12W APC at 8500 RPM on the ground. It seems to be a good choice. I have a 16x13 for those windy days and I have tried a 17x12 which was also good.

As far as props are concerned I try to select a prop which will keep the engine happy. Select a prop which will allow the engine to rev to at least 8500 on the ground and you know that the load is right. Some people stick bigger props on the YS's to get RPM down so that they meet noise but I think this approach is wrong because all you are doing is adding more load and generating more heat. You are better of to ATV the engine back if you need to drop RPM. If your engine swings a 17x12 comfortably then it probably is a good prop. I found the 16.5 x 12W gives a good constant speed.


Regards,

Peter

jlkonn

My Feedback: (1)

I have recently started building my Impact.
Going over the instructions they are very specific about using "single sided" ball links on the phenolic horns.
They caution that this WILL cause flutter!
I know on the larger Composite Arfs they double the horns and "capture" the ball between them.
Does anyone that uses the ball link have an alternative to this?
Opinions?
Recommendations?
Thanks!
JLK

PeterP

I roughened up the original horns with a bit of 80 grit sandpaper and then I laminated with some 5 oz carbon fibre cloth and epoxy between 2 sheets of glass. Great looking finish and very stiff.

PeterP

JLK,

Just found the picture I was going to include in my previous response

http://image.rcuniverse.com/forum/up...21/Ay73478.jpg

My build segment started from page 19 of this thread which may be of some value

Also do a search on IMPACT and you will find plenty of info there.

vellum2

My Feedback: (2)

Hey folks,
When you are talking about sealing the ailerons and elevators, are you talking about the open tips or the actual hinge line? The only snap that is tough for me is the F-07 45 up 1 1/2 snap... But I think it's more related to the settings than the plane... Thoughts?

Joe W.

tggilkey

Hi Joe --

I sealed the bottom hingeline of the ailerons and elevators with a product available from Northeast Sailplane Products. It's a mylar strip about 1" wide -- half of one side has a tenacious adhesive. It gets fastened to the (bottom) "wing" side of the hinge line. The other side lays against the bottom of the aileron and moves/slides with the aileron (or elevator): down when the aileron goes down and keeps the gap covered when the aileron goes up. I slotted it for the control horn. In my opinion it improves the effectiveness/evenness of the control responses. As a secondary benefit it stops the screech -- the screech didn't bother me, but other people noticed that it didn't screech any more… It comes as long, sort of rolled up piece -- it was easy to put on.

Tom

vellum2

My Feedback: (2)

Excellent - Thanks for the tip Tom!

I was out flying this weekend and improved my 45 up 1 1/2 snap with a slight aileron adjustment and a little more elevator correction at the end - I'm curious now about the gap sealing and the improvements that come with it... I suppose it weighs next to nothing?

On another note... Has anyone experienced any more breakage of these planes? From mine (and I'm riding it hard) I don't see where all the *****ing is warranted. Of course now that I said that.... Knock on composite sandwich??

Joe W.

fishgod

My Feedback: (13)

Jim,
I believe the ***** was from a poorly or insufficently designed model that got corrected after a few batches were in the field. My Impact came from the first shippment, had a dead stick landing and watched the tail just in front of the stab wrap around the plane.

tggilkey

Joe --

It has the "consistency" of heavy stiff tape so it probably weighs a few grams. I did not weigh what went on my plane. I'll weigh a foot of it tonight and let you know what I find.

Tom