RE: wing incidence
 

OK Joe!

Here you go! This is what I got back from Tower's airsupport via e-mail for you. My e-mail to them is also attached.

__________________________________________________ _____________________________


Dear Sir,

Thank you for your recent e-mail. Here are the Specs that you needed:

Stab = 0°
Wing = 0°
Motor Down = 0°
Motor Right = 1°

Thanks,
Jake M
Product Support
PS9011
NO AUTORESPONDER


>>> "Steve Steinbring" <[email protected]> 8/4/2008 11:26 AM >>>
Could you please tell me what the tail and wing incidences are for the
Super Decathalon? What is the proper incidence for the the engine as
well?

Thanking you in advance.

Best regards,

Steve Steinbring

__________________________________________________ _____________________________


Joe,


Now you have something to go on! If you haven't returned the incidence meter get the airplane shimmed up level with the stab at 0 degrees and check the wing and engine incidences.

RE: wing incidence
 

Thanks guys. The recommended engine is a .46 to a .51, so I'm not too far over the recommendation, especially with a new engine not yet reaching full potential.

Thanks for the incidences. My only question is that the wings/stab are not mentioned in the manual, but the engine is, and it says 2 degrees left and 2 degrees down, which is built into the firewall. I do still have the incidence meter.

I also want to mention that I have not been thinking too much about this plane, and have gone back to practicing pattern with my Dolphin, and having LOADS OF FUN again!!! So much fun:D

RE: wing incidence
 

Two degrees of left thrust? That's odd.

RE: wing incidence
 

Maybe it's right, I'm not home to see the manual, I just know it said 2 degrees down and 2 degrees to the side.

RE: wing incidence
 

According to the laws of gyroscopic precession, left thrust is a no-no for single engined planes with props that turn clockwise as viewed from the pliots' seat.
Some tiny amount of right thrust will help the vertical line or hover.
Trimming out a climbing tendency isn't brain surgery or require the magical formulae that only the plane manufacturer can provide. If the plane manufacturer was on the ball in the first place, your plane wouldn't be so badly out of trim.
I have designed and built dozens of planes and know that you have to be pretty far off to have a pitch control problem that can't be solved with minor elevator adjustment and shifting the CG.
The only plane I ever owned that was beyond simple adjustments at the field was a Lanier ARF Predator, one of my only ARFs [:'(].

RE: wing incidence
 

Yeah it's probably a combination of maybe a bit off of down thrust, a cg issue, and maybe a slight issue with installing the stab. All could add up to a poorly trimmed plane. Once it's fixed and flying again I'll work on it one step at a time, starting with CG.

RE: wing incidence
 

Down thrust is only needed if the plane has a very high thrust line or very high lift airfoil. Planes with semi or fully symetric airfoils and with the thrust line within a prop arc of the wing's line will fly just fine with zero up/down thrust.
I don't use an incidence meter, just a carpenter's square off of a flat table. My Robart meter froze up years ago and I've never needed to replace it.
The most fundamental starting point for you would be to ensure that the CG is at 25% of MAC. The next would be to make sure that the elevator and aileron throws are within reason [compared to what other similar planes in that class are using]. Most beginners seem to have poor control resolution from incorrect throw geometry and then try to trim it out electronically. The best way to set up a smooth flying [but still responsive] plane is with the mechanical advantage of choosing a pivot point on the servo arm close to the output shaft [1 or 2 holes out] and then place the control rod clevis well up on the control horn [like 3/4" to 1"]. The kit manufacturer usually will be a great deal of help here with this part of the set up. The greater your target speed, the less throw you will want or need.
Finally, with the plane snadbagged into place snuggly on a work table, your hands will be free to check the plane's geometry. The reward is obvious, good luck.

RE: wing incidence
 

I'd double check that left thrust. I also would take everything I see in a Phoenix ARF manual with a grain of salt. I bought their 40 size Yak-54 last week and as I have been working on it, I'm really starting to regret it.

The instructions are pretty sad. This isn't a big deal since I've built numerous kits and assembled many ARF's so I can figure things out as I go. Still, based on the vagueness and poor wording, I don't trust anything the manual tells me as far as CG and other specifications. I will double check EVERYTHING myself.

The motor mount included with the plane is a joke. It's too narrow to fit even a 2-stroke .46 and appears to be made of some sort of rubbery plastic; way too flexible for the job. I knocked out the blind nuts, filled the holes with hardwood dowels then re-drilled the firewall to use a GP adjustable mount.

The fuel tank stopper with plastic tubes is also pathetic and will get replaced.

The cowl is formed nicely and painted well but the diameter is too large for the fuselage. Once the cowl is screwed down, it will likely bulge in places. Maybe I'll try cutting a section out to make it fit better. There is also nothing but balsa sheet to screw the cowl to from what I can see. I'll have to add some hardwood to back up the screws.

The included pushrods are very tiny in diameter and will likely flex. I'll have to replace them with 2-56 rod or maybe some ny-rods.

One positive thing on the plane though is the covering. It is as close to flawless as I have ever seen on an ARF. I only needed to iron the seems as a precaution and it has stayed pretty much wrinkle free in my warm garage. Otherwise, I am not too thrilled. Hopefully it will still be a fun little plane when I am done.

On your Decathalon, I agree with combatpigg, really look at the CG and possibly move it forward some then make sure it is trimmed right.

RE: wing incidence
 

I nevered recall seeing the airleron guage in any of the boxes of my phoenix models.
A couple of twist here and there and it flew good.


That's nothing ..you can loose almost a lb if you remove the pilot figure from some of phoenix's model.:)

ahh..you mean, you replaced the line and still kept the baby tank.
All I did was glue little pieces of wood to the fuse so the cowling won't get compressed funky.

RE: wing incidence
 

HELLO!

Joe you were presented the correct incidences for the airplane by Tower! Whats this left 2 degree stuff its one degree right and no down thrust. Am I missing something here?:eek:

RE: wing incidence
 

I thought about this too. It's a pretty big gap though so I'm concerne dit will end up looking really funny. As long as it flys good though I suppose I can live with it.

RE: wing incidence
 

My cowl seems to fit pretty well.

Steve, I was just stating what it said in the manual - 2 degrees down and 2 degrees (right?).

If the stuff from Tower is correct I'll be pretty psyched. The engine and stab are on line together, which would give the wing 2 degrees of incidence in the direction of the plane climbing, which is what it does. I can try shimming the back of the wings and see what happens if this is the case. The plane does take off after surprisingley very little taxiing (when I can keep it straight that is) and like I said climbs a ton.

Got a lot of things to try, but thanks again for the reference points.

RE: wing incidence
 

It'll also cliamb if the airlerons are set too high.
If you had thicker foam on the wing's saddle it'll change the wing's angle of course.

Since it's an ARF , I'd follow the instructions but you never kown.
I've glue the rear center section pieces upside down before, if you align the airleron to it , it's going to be off.
I notice it after using the airleron guage, of course:)


For the cowling.. I used left over berch spar pieces..It didn't look bad plus it gave a path for air to exit the cowling

RE: wing incidence
 

I have a Decathalon from Pheniox and was having problems trimming. The club had me shim the front of the wing up 1/8". I am flying with a .65 K&B. CG is at recommended from manual. Flyes much better for me now. No meters were put on the wing just a dry wall sq to compare both. I do have 2 washers at the top of my engine mount and 1 on each side(due to it being mounted on an angle) to create the down thru. It is very squrilly on the ground so I abort take off if I can't get the tail up at about 15'. It does pop off the ground from there very easy.

RE: wing incidence
 

I found moving the CG up to 93mm was a huge, desirable difference. I tried playing with the wing incidence and it didn't improve flight, actually seemed less agile.

In the Super Decathlon forum many people say the CG in the manual is wrong (100mm behind leading edge). Mine was taking off well (use very light rudder input, can always add more, but once you over correct you're done for!) and flying well after removing tail weight.