Thanks in advance for your informed advice! This is my first kit and my first attempt to trim a new plane.

I maidened my 4Star60 today. It weighs in at 8 lb. 8.7 oz. Engine is a broken-in Saito 91 with a 13x8 TopFlight prop. The static balance as checked with plane inverted is in the middle of SIG's recommended range with a slight nose-down attitude. Wingtip-to-wingtip balance is spot on. Throws are spot on to SIG's recommendations.

Radio: Spektrum DX7 with dual rates. Elevator and ailerons both set up on the aileron dr switch. None on the rudder. I do not remember the switch position during initial flight activities.

Goal: Take off
Observation 1: I advanced the throttle to full and after a very long run-out I had to give it every bit of nose-up elevator just to get it off the ground (prairie dogs were ducking). Slight head breeze.
Action 1: I added a bunch of up elevator trim to try to keep the nose up and avoid a dirt nap while establishing some altitude.

Goal: Establish straight-n-level flight at 100 feet altitude.
Observation 2: I dropped the throttle back to mid-throttle to observe the plane and watched with confusion as it started to climb out of sight (well, duh - it had a bunch of up elevator).
Action 2: dropped throttle ever more (1/3) and it behaved fairly nicely. This is with about 1/4" measured of up elevator at the trailing edge of the elevator.

Goal: Land
Observation 3: This thing refused to drop into any type of glide angle when off throttle.
Action 3: used significant down elevator to force a landing - pretty hot - 6-32 nylon bolts holding LG on broke off when turning at end of runway.

So, in a nutshell:

1/2 throttle results in nose-up flight and the plane climbs - with 1/4" of up elevator

1/3 throttle results in level flight - with 1/4" of up elevator

Idle throttle results in level flight (maybe a little nose-down but very little) - again with 1/4" of up elevator.

A very experienced flier / builder and I discussed eliminating the 1/4" of up elevator - thinking that most of the bad behaviour will disappear - EXCEPT for full throttle.

Full-throttle engine thrust causes a significant nose-down attitude - especially a problem on take off. Is this due to a 13x8 pitch prop? Others use 14x6 successfully. Would the difference between an 8 and 6 pitch account for the symptoms? Or would it be only part of the problem? Something is overpowering lift from the wing under full throttle and causing nose-down flight - even with 1/4" of nose-up elevator. Is the thrust angle too much? Is there an engine mount issue that I inadvertently built into the plane causing too much down thrust? How many washers should I try between the bottom two motor mount bolts and the firewall?

Again, thanks for your input (my plane's health depends on it )

quick question do u have a indence meter u can borrow from one of the local flyers.

u need that info that the meter tells you then come back and report to use here at RCU what the tail, motor and wings are in degrees.

Krayzc - I have a Robart incidence meter. Used with no instructions. I'll check around for some instructions.

Basic question: I'm guessing that an incidence meter provides me a measurement, in degrees, between two lines. From your post I gather that it would be helpful to know that measurement between the wing chord and some line, the horizontal stab and some line and the engine thrust line and some line. What is the "some line" that I'm comparing the wing chord, stab chord and thrust line with? I'm looking at the plans as I'm typing this reply. They recommend a 2 degree down thrust (or -2 degree), a +1/2 degree incidence angle for the wing and no angle for the stab. There is no reference line on the plans to be used to establish any of the angles. Can ya help me how to establish the reference line?

Quick note: I found an online source for Robart instructions ...

yes the fuse needs to be level around the hatch area and then check wings and other mentioned areas most plans have a basic starting point of 0 on wings, stabs and motor

caps and ultimates are not the same 0 as above on some surfaces.

so take bricks or thing under the fuse to make it level in the hatch area if helps if the canopy is removeable that is how u will get the basic point to use as a reference

According to local talent - the horizontal stab can be used as the datum line for a 4Star60. I will confirm that with SIG techs tomorrow morning (they've already gone home [>:])

Kit wing incidence specification is +1/2 degree
Actual wing incidence is -1/2 degree
Differential: off 1 degree - can be shimmed at the rear mounting block
Tough to get accurate reading because aileron spans entire trailing edge of the wing from tip to fuse.

Kit engine thrust angle specification is -2 degrees
Actual engine thrust angle is nearly -3
Differential: off 1 degree - can be shimmed w/ washers at the bottom of the mount

Comments?

Pic 1 is horizontal stab
Pic 2 is wing
Pic 3 is engine mount

see if the motor is lose in the mouting
see if the tail moves
see if the wings mounts or solid

i think something is moving in flight

also see if the servo mount is moving
see if the linkage is moving on full throttle run up in the pitts

if none of the above start moving the 3 to a lower number on the motor....

A 13x8 prop will rev to 7200 rpm - with absolutely NO pull! A 13x5 will rev to 10,500 freely - plenty of pull on take off. Apparently most of my take off problems are related to poor prop selection.

The motor mount has been shimmed with 2 washers at the bottom - kicking the thrust angle back up to -2 degrees.

The wing was shimmed to adjust it to +1/2 degree from - 1/2 degree.

The static setting of the ailerons resulted in them being "down" resulting in an unintended "flaperon" alignment - nosing the plane over with neutral aileron settings.

What I learned:
Before covering - determine adherence to manufacturer's incidence guidelines and adjust as necessary.
Before flying - talk to locals about prop selection (we're well over 5000 feet where normal hobby standards just don't cut it)
Make sure that static control surface adjustment is close.

Cheers,