Rube Goldberg
02-06-2011, 12:49 PM
#1
Rube Goldberg
I am starting to build what my father would call a Rube Goldberg. You more mature guys will probably recognize the name, for the younger ones, Rube was a personality back inn the 30's [I think] that would come up with crazy contraptions.
Mine is a plane with a Nexstar wing [dihedral removed] and tail feathers, with an Escapade rear fuse section from the camel back to the tail, an old Super Tiger 40 [made in Italy], and a newly fabricated foward fuse. I plan to mount the wing high like WW1 planes.
i want it longer than the original Nexstar that was about 56" long, shooting for about 62" or 63".
Need some guidance on the following:
1. Placement of main gear on trycycle gear relative to wing.
2. Placement of wing as ratio of overall length.
3. Plan on using the CG as marked on the Nexstar wing, will this work?
4. Plan on zero wing incidence
5. Any other critical things I need.
Gary
Mine is a plane with a Nexstar wing [dihedral removed] and tail feathers, with an Escapade rear fuse section from the camel back to the tail, an old Super Tiger 40 [made in Italy], and a newly fabricated foward fuse. I plan to mount the wing high like WW1 planes.
i want it longer than the original Nexstar that was about 56" long, shooting for about 62" or 63".
Need some guidance on the following:
1. Placement of main gear on trycycle gear relative to wing.
2. Placement of wing as ratio of overall length.
3. Plan on using the CG as marked on the Nexstar wing, will this work?
4. Plan on zero wing incidence
5. Any other critical things I need.
Gary
02-07-2011, 11:48 AM
#2
Senior Member
My Feedback: (1)
RE: Rube Goldberg
First, Rube Goldberg contraptions are complex solutions to simple problems.
1. The main gear on a tricycle gear plan should be behind the CG but close enough to allow the plane to easily rotate on takeoff. For the size plane you are building I would say 1/2 to 1 inch behind the CG.
2. You should place the wing such that the plane's CG is where you want it. There is no set % of the length of the plane.
3. Yes.
4. 0K.
5. You may want to add in 1-2 degrees of down and right thrust to the engine.
Bruce
1. The main gear on a tricycle gear plan should be behind the CG but close enough to allow the plane to easily rotate on takeoff. For the size plane you are building I would say 1/2 to 1 inch behind the CG.
2. You should place the wing such that the plane's CG is where you want it. There is no set % of the length of the plane.
3. Yes.
4. 0K.
5. You may want to add in 1-2 degrees of down and right thrust to the engine.
Bruce
02-07-2011, 06:49 PM
#3
RE: Rube Goldberg
ORIGINAL: landeck
First, Rube Goldberg contraptions are complex solutions to simple problems.
1. The main gear on a tricycle gear plan should be behind the CG but close enough to allow the plane to easily rotate on takeoff. For the size plane you are building I would say 1/2 to 1 inch behind the CG.
2. You should place the wing such that the plane's CG is where you want it. There is no set % of the length of the plane.
3. Yes.
4. 0K.
5. You may want to add in 1-2 degrees of down and right thrust to the engine.
Bruce
First, Rube Goldberg contraptions are complex solutions to simple problems.
1. The main gear on a tricycle gear plan should be behind the CG but close enough to allow the plane to easily rotate on takeoff. For the size plane you are building I would say 1/2 to 1 inch behind the CG.
2. You should place the wing such that the plane's CG is where you want it. There is no set % of the length of the plane.
3. Yes.
4. 0K.
5. You may want to add in 1-2 degrees of down and right thrust to the engine.
Bruce
Thanks for the reply.
I have never put any thrust adjustments in any of the planes I have rebuilt, if they come that way, I use them thqt way. I understand the right thrust but don't know the reason for the down thrust.
Gary
02-07-2011, 08:39 PM
#4
RE: Rube Goldberg
down thrust is a way to help counter some planes desire to climb faster under higher power..
The goal is to fly level at all throttle settings without changing elevator trim.
The goal is to fly level at all throttle settings without changing elevator trim.
02-08-2011, 04:51 AM
#5
RE: Rube Goldberg
ORIGINAL: foodstick
down thrust is a way to help counter some planes desire to climb faster under higher power..
The goal is to fly level at all throttle settings without changing elevator trim.
down thrust is a way to help counter some planes desire to climb faster under higher power..
The goal is to fly level at all throttle settings without changing elevator trim.
Thanks. will give it a try on this plane especially since it has a trainer wing.
Gary
02-08-2011, 08:51 AM
#6
RE: Rube Goldberg
Gary, with the engine below the wing, as you intend, you can see that the line of thrust and the drag from the wing will tend to rotate the model nose up as you go faster. If you are ok with this, and many full size aircraft are like this, and you simply retrim the plane with power changes, then leave things as normal. Modellers, flying from the ground and often unable to see the horizontal (pitch) attitude, often resort to using downthrust, which brings the line of thrust closer to the line of drag to minimise the effects, cause we don't do much trimming of the model just for changes in power.
Evan, WB #12.
Evan, WB #12.
