Best plane for AMA Pattern competition

[danskis]

Long but interesting paper on trimming.

Triangulation_Trimming.pdf (shopify.com)

After looking at all the competition planes and reading about them I'm doubtful of actually producing a real pattern plane in foam.

After re-building my 60% Kwik Fly and flying it side by side with my swappable Spitfire I'd have to give the edge to the Spitfire. Of course today was the re-maiden after rebuilding the fuse and I obviously need to play with the CG and wing incidence. Playing with wing incidence is an argument for rubber banding the wing on.

 

[model14]

I agree there is no way a foam board plane could be competitive in AMA pattern competition. However, i like to watch precision aerobatics and I want to learn how best to do it, and I am not willing to invest the money in an expensive plane that will no doubt crash a bunch of times before I do. Right now, I am having fun getting the most I can from the upside-down FT Simple Stick. Heck, I still can't fly a straight and level line to my satisfaction, especially in our cross winds we always seem to have, but I'll keep trying. It certainly isn't the plane holding me back.
One thing to be sure and do if you build the low-wing Simple Stick is to reenforce the tail feathers with popsicle sticks and skewers, as shown in the picture. I also reenforced the nose area to handle a larger motor and make for lessened crash damage.

 

[Piotrsko]

Instead of futzing with the wing saddle, try a full flying elevator to do incidence experiments. That way it is just a trim change.

Pattern plane in foam is possible, winning a contest with one, probably not mostly because of structure limits

 

[model14]

Additional bracing I've added. The vertical stab was moving all over the place. Looks like Sunday may be a go. I'm trying 6S power and a 10 x 4.5 HQ prop, which gives me 250 watts. The plane with battery weighs 660 grams. Hope to get some video.

 

[danskis]

@Piotrsko Well the plane is already built and it has a conventional FT tail assembly. And although its an interesting idea I don't think I'm going to rip the tail off and put on a flying elevator. However, I used rubber bands to hold the wing on this version so its a simple matter of shimming the leading or trailing edge to change decalage . My F3RES powered glider has a flying elevator - its a little tricky to trim. The other argument for not putting on a flying elevator is that no pattern ships use them.

 

[L Edge]

Are you a pattern pilot?
Are you just another pilot? The biggest fall down is you can't isolate the left hand 2 axis into individual components and keep one the same while varying the other with accuracy.

Test:
Put your radio on and go to the monitor screen and look at throttle and rudder positions. Use left hand and move throttle 1/2 up so it should approximately read 0.
Now add some right rudder and read the value of the rudder.(try 30 for instance). Now increase throttle to 3/4 smoothly and keep eye on number above rudder as the throttle goes up. Object is to keep the rudder the same number(30) as the throttle moves up. Bet it will vary 20 or more if you are bad..
Now try -30 rudder and change (up/down) throttle ,see how good/bad it is.
A good pattern pilot can keep it within a few numbers. Otherwise, work at it and see your improvement.

Additional point. Can you move your throttle from one point to another and know exactly what the throttle readings before and after within 2 or 3 numbers? Why?

 

[danskis]

I'm not kidding anyone - I'm just a guy that goes around boring holes in the sky while doing a few basic maneuvers. But I'd like to get better. After all, after 3 years of flying I'm starting to appreciate how well a well trimmed plane flys compared to a poorly trimmed plane. And I know I need to get my left hand up to speed (I don't have a simulator).

This is the 60% Kwik Fly One on the bungee launcher - I use the launcher cause I don't like the way planes look with wheels down.



Its got a 36" fully symmetrical airfoil wing made of xps foam. Its the same airfoil that was on the plans. The wing came out with a little anhedral but after flying it a few times I see it has a slight dihedral. BBQ skewer main spar. After re-building the fuse once I rough trimmed it out a couple of days ago. Since then I took a good look at the motor angles. The downthrust was very close to what was on the plan but the plan called for no right thrust and my crooked firewall definitely had some right thrust. I put a few washers in and flew it again today. After a little trimming I could fly it pretty much the length of the field hands off. I noticed that I had to add a little left rudder and that it wouldn't fly inverted at a 45% angle without some significant down elevator. After getting it on the ground I noticed that the motor is mounted off center - a little to the left. This would cause a right turn - which I corrected with left rudder. I'll remount the motor closer to centerline. I also noted that "trimmed" in the air I had some up elevator. I'll move the battery/CG back and see if I can get a little bit better inverted flight. I wouldn't call this a "pattern plane" even though it was in the 1960s. Its what they would call an advanced sport plane right now.

The crash was caused by the servo being off center after landing in the grass and having the servo arm forced a couple of notches to the back - throwing the aileron off. The servo is pretty close to the thickest part of the wing. I put some "protectors" in front of the servo arms to try to keep this from happening again.



While this plane is smaller than my swappable Spitfire its slower using the same motor and prop. Its probably a little heavier too. Maybe its that symmetrical airfoil. I'll keep playing around with it to see how well I can trim it out.

 

[Bo123]

Just gonna drop a bombshell and say that scale aerobatics is better than pattern aerobatics….

 

[Tench745]

Just gonna drop a bombshell and say that scale aerobatics is better than pattern aerobatics….

I'm going to drop another bombshell and say that without any explanation or justification, your bombshell could be considered trolling.
Care to elaborate on your opinion and step away from the troll-bridge?

 

[model14]

Danskis, keep it up man. I'm behind you due to weather but I think tomorrow is a go. I hope to catch up to you a little. I sent a note to FT asking them to develop a low-wing version of the Simple Stick that is geared towards precision aerobatics. I'm sure they have a lot on the plate. One thing I noticed in looking at the Flea Fli plans is that the airfoil thickness is almost twice that of the FT SS (Simple Stick). That would mean more drag, requiring more power, but after reading the Triangulation Trimming article I see where that may be of benefit.
I layed out a plan for tomorrow that works through trimming adjustments recommended int the Kindle book and the Triangulation article.
Wish me luck.

 

[Bo123]

I'm going to drop another bombshell and say that without any explanation or justification, your bombshell could be considered trolling.
Care to elaborate on your opinion and step away from the troll-bridge?

Yeah I guess it could be considered trolling. I just prefer scale aerobatics as thats what I fly. Maybe my comment wasn’t necessary.

 

[Piotrsko]

Thicker airfoil doesn't necessarily mean more drag. Does mean stronger, more lift, slower stall so may be valuable during manuevers.

 

[L Edge]

One additional point for you pattern pilots, you should take a step back and see how well the plane was assembled and symmetrical is all 3 axis?

Did you eyeball and measure things.

By that, is the fuse, wing, perpendicular
Sighting, Is the elevator match up to the wing?
Did you measure the distance from wing to fuse?
How about wing tip to elevator tip on each side.
Measure wing tip to ground (dihederal)
Is the motor/prop perpendicular in all 3 axis?
How about twist, bending on the wing, elevons etc.
Are your surface controls the same deflection?
Do you have gaps in your surface controls?(airflow from under to top)
etc,etc.

So find articles to help build it properly. The more it is symmetrical, least errors of flying.

I have three of these and an app for the phone to get it right. I bet you right now the wingtip to elevator tip is off by at least a 1/4" or better on yours and the wing is not in the saddle(tip to ground) the same dimension. That's why I ask someone to make left and right turns in a video to check.

So suggest you start off there before you do inflight adjustments. Notice I have a 90 straight edge to help you.

 

[danskis]

So I"ve never seen a modern pattern plane in person. I've been looking at some online and I was wondering what sort of airfoil they are using for these planes? The old pattern/sport planes have very thick symmetrical airfoils but I don't think that's what they use now. Anyone?

 

[Piotrsko]

Airfoils go in cycles. Early had thick mostly or fully symmetrical kinda blunt front ends much like on an ugly stick 60. Then somebody won a couple contests with a much thinner NASA profile and whammo! Somebody built an old timer again with the thick blunt wing and won a couple contests...... you want whatever you use to be generally stable, predictable performance, and like @L Edge said easy for the judges to judge. AFAIK, pilot skill is the determining factor but stable goes where you point it is sceond.

 

[L Edge]

So I"ve never seen a modern pattern plane in person. I've been looking at some online and I was wondering what sort of airfoil they are using for these planes? The old pattern/sport planes have very thick symmetrical airfoils but I don't think that's what they use now. Anyone?

Just like people, different planes have different tendencies. So designers vary the wing etc. to fit different styles of flying. No pattern plane is superior. Like Piotrsko said, it is the pilot's< skills.

 

[L Edge]

Model14 and danskis:

This caught my attention if you can get Model Aviation magazine dated December 2022 on right top page 48 labeled Trio of Aircraft.

A pattern plane using Flight Test methods and material(3rd generation pattern plane) has a power pack C 2,200 mah battery. It has a symmetric (48") wing and weighs 24 oz with the battery. It has aa 1/16 " plywood box(this caught my attention ) inside which attaches the motor, battery, wing together and the rest is Flite Test Maker foam board.

He claims it will fly the entire AMA pattern and is super easy to land.

Even the picture above the article sure has a distinct shape of a pattern ship of the 70's. Included is an e-mail address so perhaps he can help assist you or maybe has some plans he would share.

AMA site allows you to look at the digital copies of Model Aviation magazines. If you can't find it, PM me.

 

[L Edge]

Had a little time, so I dragged the Curare test plane out. All fiberglass fuse. Notice the long length for the tune pipe. Use this one to relocated the 16 oz fuel tank at the CG so as fuel was used it did not change the CG., Made flying the pattern much easy at the advanced level for my son.

In the background is a GLH TD 049 when racing, topped 100+mph. Going to try both this spring.

 

[danskis]

If you want to look at some modern pattern planes go here

 

[L Edge]

If you want to look at some modern pattern planes go here

If you want to look at some modern pattern planes go here

The other added factor is the carbon fiber props. Expensive compared to APC"s, used those on a 55c plane and it really improved the overall performance. Even added a carbon fiber nose cone that is exceptionally light and well balanced.