World Models Ultimate 120s
#53

Happy to report that, since my post and question above, I have been able to successfully maiden the model. As should be evident, I had the poor covering supplied with the model replaced and I would encourage anyone else with this model to do the same. Otherwise, you will be having to constantly iron down the covering and in some instances apply adhesive to keep the edges fixed to the balsa.
The flying experience was quite mixed. On take off for maiden flight, the model appeared to be tail heavy requiring quite a bit of down trim to achieve straight and level flight. Once straight and level she was well behaved not showing any bad tendencies. I will admit that, as possibly with most modellers, I am usually a bag of nerves when I maiden an aircraft. The landing is evidence of same(please see the armature YouTube video). I have moving the battery forward to improve the tail heavy tendency however, after moving as far forward on the cowl as possible, there was no change. I have since secured around 9 ounces of stick-on-weight which I plan to apply just behind the spinner. If there is improvement in the tail heavy tendency, I will remove the stick-on-weight and move the engine forward so as to maintain flying weight as it is now.
I will provide further updates once I am able to fly with the stick-on-weights. Until then, stay safe.
DaleD





The flying experience was quite mixed. On take off for maiden flight, the model appeared to be tail heavy requiring quite a bit of down trim to achieve straight and level flight. Once straight and level she was well behaved not showing any bad tendencies. I will admit that, as possibly with most modellers, I am usually a bag of nerves when I maiden an aircraft. The landing is evidence of same(please see the armature YouTube video). I have moving the battery forward to improve the tail heavy tendency however, after moving as far forward on the cowl as possible, there was no change. I have since secured around 9 ounces of stick-on-weight which I plan to apply just behind the spinner. If there is improvement in the tail heavy tendency, I will remove the stick-on-weight and move the engine forward so as to maintain flying weight as it is now.
I will provide further updates once I am able to fly with the stick-on-weights. Until then, stay safe.
DaleD





#54

Went out flying on Friday with 3 ounces added just behind the spinner. On take off, I needed to remove a few clicks of the down trim that was required for straight and level flight.

This however did not address the issue as the model was now nose heavy as determined by the 45 degree up line test. The deduction was that something must be off with the incidences.
Yesterday, I discovered that the wings had a positive incidence relative to the horizontal stabiliser(stab). The lower wing +1.5 degrees and the upper wing 2.0 degrees.
I have temporarily added shims to the lower wing saddle to bring the wings on the same plane as the stab.

Hoping the next flight will yield the desired results where the remaining down trim can be removed.
Another update soon.
DaleD

This however did not address the issue as the model was now nose heavy as determined by the 45 degree up line test. The deduction was that something must be off with the incidences.
Yesterday, I discovered that the wings had a positive incidence relative to the horizontal stabiliser(stab). The lower wing +1.5 degrees and the upper wing 2.0 degrees.
I have temporarily added shims to the lower wing saddle to bring the wings on the same plane as the stab.

Hoping the next flight will yield the desired results where the remaining down trim can be removed.
Another update soon.
DaleD
#55

Turns out the issue was with the incidence. With the shim installed on take of, I now needed to input up trim in order to attain straight and level flight. All the down trim that was previously introduced for straight and level flight prior to the shim being installed was removed. Unfortunately, I was only able to complete one flight. The next flight will be without the stick-on-weights.
Until next time, enjoy smooth landings.
DaleD
Until next time, enjoy smooth landings.
DaleD