Here is my latest ARF build, a Maxford (Green) Models Jenny. She sports a 38 inch wing and comes in at just a little over 15.5 oz with a TP 910 3 cell for power.
What caught my eye was that for an ARF the wings and tails are fully rigged. And to make things really surprising is that the wings fold down for storage while maintaining the full rigging.
As is typical for me I saw some issues with the force arrangement of the flying surfaces right out of the box. Many designers fail to understand the amount of down wash coming off the two sets of wings. As a result they added far too much down thrust to the motor. To bring the tail plane (stab) closer in line with this downwash I raised the leading edge of the stabilizer 2mm with a simple wedge. I then balanced this by taking out a lot of down thrust by adding 1mm washers under the lower motor mount bolts.
I love that the rudder and elevator are on pull pull set ups. the ailerons are standard rigid wire push rods.
When it came to the wheels they were a no go, being of the soft wide (cub looking) type. I decided to use Williams Brothers vintage type wheel with spring retainers.
Well much to my surprise, she is a lively ship. I thought the ailerons would be painfully slow. While not fast they were adequate. The secret to her performance is that she is right around 100 watts per pound. Power on, power off slow and fast speeds there is little change is airplane attitude. I love doing stall turns as there is only a little roll coupling.
The only down side I found was that the fixture built wings distorted a bit when the covering was shrunk. Making it a bit of a chore to install the carbon through rods. Also as time has gone by the adhesive on the transparent film is letting go.
Those with a sharp eye might have noticed that I added 3 grams of tail weight. Don't be afraid to add weight where needed to bring a model into proper trim. The CofG on most models will almost always need to be pushed aft after the test flights.
What caught my eye was that for an ARF the wings and tails are fully rigged. And to make things really surprising is that the wings fold down for storage while maintaining the full rigging.
As is typical for me I saw some issues with the force arrangement of the flying surfaces right out of the box. Many designers fail to understand the amount of down wash coming off the two sets of wings. As a result they added far too much down thrust to the motor. To bring the tail plane (stab) closer in line with this downwash I raised the leading edge of the stabilizer 2mm with a simple wedge. I then balanced this by taking out a lot of down thrust by adding 1mm washers under the lower motor mount bolts.
I love that the rudder and elevator are on pull pull set ups. the ailerons are standard rigid wire push rods.
When it came to the wheels they were a no go, being of the soft wide (cub looking) type. I decided to use Williams Brothers vintage type wheel with spring retainers.
Well much to my surprise, she is a lively ship. I thought the ailerons would be painfully slow. While not fast they were adequate. The secret to her performance is that she is right around 100 watts per pound. Power on, power off slow and fast speeds there is little change is airplane attitude. I love doing stall turns as there is only a little roll coupling.
The only down side I found was that the fixture built wings distorted a bit when the covering was shrunk. Making it a bit of a chore to install the carbon through rods. Also as time has gone by the adhesive on the transparent film is letting go.
Those with a sharp eye might have noticed that I added 3 grams of tail weight. Don't be afraid to add weight where needed to bring a model into proper trim. The CofG on most models will almost always need to be pushed aft after the test flights.
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