hvp Albatross help needed
05-27-2008, 10:00 AM
#1
Banned
Thread Starter
hvp Albatross help needed
I am a first time waterplane builder/assembler, but a loooong time designer builder.
I got this years ago at Dymond's grand opening, but just lately decided to put it together while waiting for some gun kits from Arizona Modelers :-((((((((((((((((((, but that's a whole nother story.
I know that this Albatross has been around a long time, and I have read everything about it that I could find on RC Groups and RC Universe, but nothing adddresses the concerns that I have.
#1 Picture 1 is the motor mount and the slots in the wing. If you fit the mount flush into the wing (the way I think it was intended), the motor takes on an incidence of zero with respect to the bottom of the wing, or roughly -1 with respect to the airfoil (Clark Y).
With the horizontal stab at zero, the wing mounts such that the airfoil is at 2, putting the motors at +1.
The instructions say to push the front of the mount down to 2mm above the surface and glue them in. That puts the motor at -2 from the airfoil. I can only guess that this is what all the chatter about bow spray, and the necessity of extended spray rails is all about.
I couldn't understand why this was necessary until I started playing with the engine cowling. Apparently what happened was that the original design for the engine thrust line was correct, but the motor mount put the centerline of the motor well above the center of the cowling.
My current inclination is to redo the mount, so the original thrust line is maintained, but centered on the cowling.
Any comments or suggestions are gratefully accepted.
#2 CG. Root chord is 8.5"
Tip chord is 5.125
Leading edge sweep is 2.562
1/2 span is 27.375
Everything I can find out says that cg should be at 2.91" from the leading edge at the center of the wing, but the instructions say 50mm (1.97"). That would appear to me to make this bird nose heavy, and create even more problems in takeoff.
Is it just me? Am I missing something? Is there any hope??
Les
I got this years ago at Dymond's grand opening, but just lately decided to put it together while waiting for some gun kits from Arizona Modelers :-((((((((((((((((((, but that's a whole nother story.
I know that this Albatross has been around a long time, and I have read everything about it that I could find on RC Groups and RC Universe, but nothing adddresses the concerns that I have.
#1 Picture 1 is the motor mount and the slots in the wing. If you fit the mount flush into the wing (the way I think it was intended), the motor takes on an incidence of zero with respect to the bottom of the wing, or roughly -1 with respect to the airfoil (Clark Y).
With the horizontal stab at zero, the wing mounts such that the airfoil is at 2, putting the motors at +1.
The instructions say to push the front of the mount down to 2mm above the surface and glue them in. That puts the motor at -2 from the airfoil. I can only guess that this is what all the chatter about bow spray, and the necessity of extended spray rails is all about.
I couldn't understand why this was necessary until I started playing with the engine cowling. Apparently what happened was that the original design for the engine thrust line was correct, but the motor mount put the centerline of the motor well above the center of the cowling.
My current inclination is to redo the mount, so the original thrust line is maintained, but centered on the cowling.
Any comments or suggestions are gratefully accepted.
#2 CG. Root chord is 8.5"
Tip chord is 5.125
Leading edge sweep is 2.562
1/2 span is 27.375
Everything I can find out says that cg should be at 2.91" from the leading edge at the center of the wing, but the instructions say 50mm (1.97"). That would appear to me to make this bird nose heavy, and create even more problems in takeoff.
Is it just me? Am I missing something? Is there any hope??
Les
