Bicyle landing gear - viewpoints please
01-18-2011, 08:04 AM
#1
Thread Starter
Bicyle landing gear - viewpoints please
Howdy, I am considering to use a "bicycle" landing gear for a canard design currently on the drawing board. This is an uncommon solution and just about the only example I know of is Andy Lennons Swan design (see attachments)
Unfortunately Andy Lennon does not elaborate on the performance of the "bicycle" gear neither in his book nor in the Swan article as published in Model Builder (Oct.1989)
So before I proceed along this line I would invite you all with "bicycle gear" experience to share with us....Thank you..!
Cheers/Harald
Unfortunately Andy Lennon does not elaborate on the performance of the "bicycle" gear neither in his book nor in the Swan article as published in Model Builder (Oct.1989)
So before I proceed along this line I would invite you all with "bicycle gear" experience to share with us....Thank you..!
Cheers/Harald
01-18-2011, 09:48 AM
#2
Join Date: Oct 2002
Location: Chilliwack, BC, CANADA
Posts: 12,425
Likes: 0
Received 22 Likes
on
19 Posts
RE: Bicyle landing gear - viewpoints please
I've never tried a bicycle setup but I can say that the drag from the outer skids or wheels would need to be low to avoid pulling the model into a bad yaw on landing or takeoff if you're not flying from a paved runway. In the Swan's case he's using wheels which I think would get caught up and foul badly in grass. For grass I'd suggest that long smoothly bent back wire skids would work far better than what the Swan uses.
I would also want the skids to be between the two wheels so that their clearance from any grass is greater when the model is nose high for either touchdown or lift off to again avoid the skids fouling in the grass. On pavement and with wheels that would not be so much of an issue. But this means that the wheel location for the Swan is poor by my thinking. They need to be place up high to avoid dragging when the nose lifts. And that means a lot of lean when taxying.
I'd say that for a good arragement look at the U2 setup. Closer in outrigger wheels that rise up as the aircraft goes nose high. The B52 runs counter but consider that the wing flex in that plane changes everything. A loaded B52 has the outriggers firmly on the ground with full tanks but the ourtriggers are a good 6 to 8 feet in the air from lift flex before the mains get off the ground. And due to the massive flaps and angle of attack change that the flaps produce that the plane lands and takes off "flat". So that's a unique plane in this way.
I would also want the skids to be between the two wheels so that their clearance from any grass is greater when the model is nose high for either touchdown or lift off to again avoid the skids fouling in the grass. On pavement and with wheels that would not be so much of an issue. But this means that the wheel location for the Swan is poor by my thinking. They need to be place up high to avoid dragging when the nose lifts. And that means a lot of lean when taxying.
I'd say that for a good arragement look at the U2 setup. Closer in outrigger wheels that rise up as the aircraft goes nose high. The B52 runs counter but consider that the wing flex in that plane changes everything. A loaded B52 has the outriggers firmly on the ground with full tanks but the ourtriggers are a good 6 to 8 feet in the air from lift flex before the mains get off the ground. And due to the massive flaps and angle of attack change that the flaps produce that the plane lands and takes off "flat". So that's a unique plane in this way.
01-19-2011, 12:10 AM
#3
RE: Bicyle landing gear - viewpoints please
One problem with bicycle landing gear as on the B-47 & B-52 is that neither of these aircraft 'rotate' to take off or 'flair' to land.
Both just take off when they reach flying spped & must be flown back onto the deck. This may make take off & landing longer for a model, no problem for the full size with 3 mile runways! - John.
Both just take off when they reach flying spped & must be flown back onto the deck. This may make take off & landing longer for a model, no problem for the full size with 3 mile runways! - John.
01-19-2011, 07:31 AM
#4
Senior Member
Join Date: Aug 2003
Location: Wilson, NC,
Posts: 2,057
Likes: 0
Received 0 Likes
on
0 Posts
RE: Bicyle landing gear - viewpoints please
Hi canardlover
I'm sure you have seen the two SPAD Pusher Canards I have flown; a straight wing and a swept wing. My vertical stabilizers also extend well below the vertical CG, similar to the Swan you refer to. I did this to help while doing a knife edge. Mine do not have bicycle main gear so I do not have direct experience for you. However, judging by the amount of dirt that accumulates at the bottom of my vertical stabilizers and rudders, they frequently dig into the ground (always on a grass field) since I use a very generous flair to slow the plane at landing. In crosswinds the plane usually does not touch down on both mains at the same time. I have never noticed any change in direction at touchdown due to one side digging in before the other. Good luck with your design.
I'm sure you have seen the two SPAD Pusher Canards I have flown; a straight wing and a swept wing. My vertical stabilizers also extend well below the vertical CG, similar to the Swan you refer to. I did this to help while doing a knife edge. Mine do not have bicycle main gear so I do not have direct experience for you. However, judging by the amount of dirt that accumulates at the bottom of my vertical stabilizers and rudders, they frequently dig into the ground (always on a grass field) since I use a very generous flair to slow the plane at landing. In crosswinds the plane usually does not touch down on both mains at the same time. I have never noticed any change in direction at touchdown due to one side digging in before the other. Good luck with your design.
