In May of this year, I took delivery of a BJ Craft Epilogue ARC from F3AU. Upon unpacking the contents I was surprised by the shape of the rudder. The rudder incorporated a counterbalance similar to my Invitation G2. This was unlike pictures I had viewed of the Epilogue to date online. In addition, there was a nose ring attached to the exterior of the original molded nose ring which had a noticeable change in the right and down thrust amounts. As I continued to unpack components I quickly noted the double taper of the wings and stabs and general location on the fuse were what as I had expected. Concerned about the rudder shape and nose ring thrust modifications I sent an inquiry to F3AU and BJ Park. The following is the response I received direct from BJ Park about the design changes.
From BJ Craft:
I am BJ Park, owner of BJ Craft. I am very sorry for giving you trouble and confusion. If you do not like changed design, you can return the plane, the return cost shall be paid to Mike by me. English is not my mother tongue and culture barrier shall be, I may commit indecent act in the text, please understand and forgive me.
I am going to say about the modification of the design. I have a mistake that I did not inform this to Mike. Sorry for Mike. I am engineer rather than business man, so I commit mistake like this case Especially when I develop new models. please understand this mistake. The reason that I change vertical fin is 3 causes.
1. The height of wood crate is determined by the height of the vertical fin. As you know well I ship plans all over the world air shipping by UPS/DHL Reducing the height of Fin, wich can save USD600~800/pc. You can see if you check freight in their home page. This is very important element for dealers.
2. Epilogue's counter balance. Feed back from world wide about 1st. lot production, rudder to aileron mixing is no need or recovery a bit. To reduce recovery, counter balance is, it pushes top of the rudder post when you use rudder, due to pushing makes counter recovery roll. It is not big, reuces mix about 1%.
3. Height of fin in Nuance G2 and Epilogue has higher fin at first lot, that is "new spec" design. this is the spec about design coefficient for aircraft plane form (geometry) which is related with pattern trackng. Epilogue is 2020 versoin of 'new spec" which includes stability (tracking) in 8~10m/sec strong cross wind. 1st lot of Nuance G2 was old version it was 6~ 8m/sec strong cross wind. In the 2nd lot of Nuance G2 improved into 2020 version. I realized that feedback from worldwide has a margin to improve. To match 2020 version tail (horizontal, vertical) volume coefficient, vertical fin height of 1st lot Nuance G2 is necessary to highten. This improvement can't be felt by the fliers who fly the plane in the not srong wind. The improvement that I do in detail may not necessary for the common fliers in worldwide but aircraft designer test and understand those in detail for future technology. The improvement of performance is important but more important is customers' needs.
P.S. : Epilogue in the F3AU pic is the epilogue prototype which is flown by me WC in 2019. This plane is deigned only for me, my flying style and my propulsion. Drive unit for this plane is 22*16 prop runs at 7000RPM (4000w) this is used only by me in the world. Unique plane makes unique flying possible. unfortunately it needs unique design. Production Epilogue lot was redesigned for common fliers and popular propulsion in the world,even if it is not perfect one but can be satisfied worldwide
The plane perfetly fit to your flying field only is able to be easily designed by me, but your flying field is the micro part of the world, my design is flown in the fields from 0~3000m above sea level, besides this, many elements give effect to the aircraft design. So my design is not perfect but is stisfied all over the world and prototyhpe and production type is different from each other.
Canalizer for prototype is only one ( wrong design too small) so I changed it into present one. Anhedral for big prop was also deleted. Wing fence in the pic was changed into wing tip fence, which can be easily changed larger or smaller depending on the customer circumstances. Besides these, the moment, wing position ( I like low wing) tail volume etc, etc.
I should have provided the production type picture, due to various reason I couldn't, it was my mistake. Story was long, F3A market is so small that factory couldn't employ enough workers. But I am doing my best to do all the things as long as I can.
Rudder configuration BJ referenced of his WC 2019 version
Rudder shape of the version I received.
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