Landings

[Garf]

I had a hard time with landings at the KOI. I am set up to fly over grass with large wheels. I notice most of the pro stunt flyers use small wheels on pavement. Does wheel size make a big difference?

[Brian Massey]

I fly on grass too, and think 3" wheels to be the "norm". I'm just guessing that smaller wheels will have less bounce, and be a bit more aerodynamic. I'll be watching the answers here too.

Brian

[Bob Whitely]

Ok guys, here is the landing gear setup class 101. This will always work
on any plane even All American Sr.'s and Ringmasters. First I will explain
why the planes bounce on hard surfaces and not on grass then tell
you how to fix it.

Virtually all our models are launched with the nose turned away from the
pilot. This is at least tangent to the circle and usually pointed out much more.
The result is a skidding of the wheels on launch but does not show up
when flying on grass as the wheels simply slide on so no effect is felt.
When launched on a hard surface the wheels are unable to roll because
of the outward angle of the wheel in relation to the aircrafts' yaw to the outside
of the flight path. The resulting skidding of the wheels on the hard surface
makes the wheels chatter and the plane yaw side to side.

On landing things get a lot worse. The plane is yawed to the outside of the
circle and upon touchdown the wheels want to roll to the outside of the circle
while the plane continues on a circular path.

[Bob Whitely]

Stupid computer wouldn't let me go any further so here is the rest of L/G 101.

The fix for all this is to angle the wheels in towards the pilot so as to
approximate a zero angle of the wheels to the circle track that the plane
will follow on landing and takeoff. This is usually about 3-5 degrees to the
left of the fuselage centerline. Be sure to  tweak both wheels. Do not stress
about the plane coming at you on takeoff, it won't. Wheel size makes no
difference. Do the wheel thing and amaze all your friends and relatives that
kept telling you that landing a plane was not your best maneuver.  RJ

[Ward Van Duzer]

One other very important factor in grass/pavement landings is the position of the landing gear axles. Long, long ago (I think it was Windy) someone showed a movable LG on a set of plans. It was a dural gear that could be placed further forward for grass. Object: Prevent nose overs on takeoff and landings. For pavement flying you could move the gear backwards until the axles were even with the leading edge of the wing. Smoother takeoffs and landings. This is the major reason OTS airplanes have so many bounces on pavement. Of course, you are not allowed to move the gear in OTS from the position of the original design.  

FWIW

Ward-O  

[Howard Rush]

The fix for all this is to angle the wheels in towards the pilot so as to
approximate a zero angle of the wheels to the circle track that the plane
will follow on landing and takeoff. This is usually about 3-5 degrees to the
left of the fuselage centerline. Be sure to  tweak both wheels. Do not stress
about the plane coming at you on takeoff, it won't. Wheel size makes no
difference. Do the wheel thing and amaze all your friends and relatives that
kept telling you that landing a plane was not your best maneuver.  RJ

Thanks a bunch, Bob. I can sure use the landing points.  I had figured out the fore and aft placement, but I have been angling my gear in the wrong direction. 

[Bob Whitely]

Howard, Most of the time I get your humor but not sure this time. Have you
really been pointing your wheels to the outside? If so, you are correct in that  it is
the wrong direction.  You are right about fore and aft gear placement but it
is a very minor gear setup in the trim scheme. The recommended placement of the wheels
is determined by the cg. For grass the bottom of the wheels should touch a point that
is 13-15 degrees in front of the cg. Draw a line from the cg to that point on the ground
and that will tell you where to put the wheels. For hard surfaces the angle should be
about 5-7 degrees provided the wheels roll nicely cause if they don't it will require
constant prop replacement.  I'm just sayin'.....RJ

[peabody]

I awarded Howard 40 points for a landing that he made in a pretty-much gale......still remember it....it was kewl

[Howard Rush]

Howard, Most of the time I get your humor but not sure this time.

I was actually trying to be serious.  I don't know where I got the notion to point them out, but I do. 

[Mike Keville]

While I am far from being in the SSF (Serious Stunt Flyer) league, I'll have to endorse Bob Whitely's recommendation.  Six years ago I was bouncing my landings on asphalt when he recommended a slight toe-in on the LG/wheels.  Bingo!  Worked like magic - not only vastly improved the landing scores but had no effect whatsoever takeoffs.

And yes <blush>, this was with a Ringmaster.

Trust me.....RJ knows what he's talkin' about.

Just sayin'.....

[Mike Lauerman]

Agree 100%, Bob and Uncle Mikey. My flying pard adjusted my 'trick' wing mounted gear to the 'inboard' on my Sterling F51, and it taxied on the main gear for 1/2 the circle!
Landing was textbook, (er, anti-Sterling textbook!) just came in and rolled so nicely I wanted to whip the landing taxi around again...Big difference.

[PJ Rowland]

I do similar to Bob.

When Im setting up the roll angle of my ship, I push it outside on the road and try to get it to track inward slightly.

I have a mock circle edge made up that allows me to see the circle edge relicated.

[Bill Little]

Thanks for the lesson, Alfadawg!  It will help out many people.

BIG Bear
RNMM/AMM

[FLOYD CARTER]

"Toe-in" is one thing, but setting both wheels toward inboard will get you closer to SLOTO (Slack Lines on Take Off).

I try to set both wheels straight ahead.  My landing roll is long, and as smooth as I could want.

Floyd

[Bob Whitely]

Setting the wheels straight ahead is illogical as model rolls in a circle. Therefore
the wheels WILL skid and chatter cause they are trying to go straight and the
plane is trying to turn left. Toe-in works well on cars and RC planes but not
for what we do. I know all the above is hard fact and is in concrete. Besides
it works every time.  RJ

[Jim Kraft]

Thanks for that Bob. Now I have to go down the basement and adjust the wheels on about 20 planes. One things for sure though. I bet they take off and land better than they ever have.

[Garf]

Attempting to set the gear "slightly" inboard would be next to impossible, because it is so close to being "too much". I would use the same reasoning as setting engine offset. Set a little offset to make sure you have no inset. If you accidentally set too much inset, the results could be disastrous. I would set the gear for straight ahead and readjust as necessary.

[FLOYD CARTER]

Yes.  I just have too much time and money invested in models to see one fly past me on take off.

Floyd

[John Fitzgerald]

Mine tend to try to come inward much of the time on takeoff.  I always fly on grass, and it's not the smoothest. Many times I have to take a couple of quick steps backward on takeoff while holding the lines up out of the grass. Wheels are set straight ahead as far as possible.  The tailwheel might cause a little outward turn, but that's off the ground in two feet.
Maybe a plywood launching deck would help?

[Gary Anderson]

Hi guys,
Bob is correct, if you feel the plane is getting to light on your lines, just step back with the plane and it will work every time. Thanks for your great input Bob

Gary

[Michael Massey]

Just a word about "light lines" and stepping back.  GARY, listen up or this will be an expensive hobby.  It takes but a very brief moment for slightly slack lines to grab a tall weed.  Depending on the "tentacle tenacity of the clover," your plane may take a trip all it's own.  Gary can attest to that.  He was there when my Pathfinder did that very thing.  The lines were slightly slack for a very brief moment.  It was ugly!

[Serge_Krauss]

It is probably worth noting that since they're ahead of the models c.g., "tail-dragger" landing gear aimed along the fuselage center line aren't pointed tangent to the circle, but rather outward. Depending on line length, a bit of left bias would have them rolling along the circle.

SK

[Bob Whitely]

Serge, Exactly right! This also means that with a tri-gear plane the mains will
need just a little right bias so as to accomplish the same thing. Also nosegear
will need to be pointed just slightly to the left.  Voila! We now have a model that
will take off and land very nicely. Until you have set up your plane correctly those
40 point landings will continue to be only a dream....RJ

[Dick Pacini]

Toe-in works well on cars and RC planes but not
for what we do.

Now I'm confused.  I thought a bit of toe-in was being desirable.

[Mark Scarborough]

Interesting,,
I am not an expert, but landings are one of my highest scored manuevers,, take offs are my next. Last year I was averaging pretty solid numbers ( without looking at the score sheets I cant recall, but I did see a lot of 37 and 38 as  I recall) My wheels are pointed as dead straight as I can make them.
I have not seen any wheel hopping on takeoff or landing.
I guess it may be back to "whatever works for YOU" but I have not had any problems with straight wheels,,

[Jim Kraft]

I have wondered about this for a while. On my Taurus it is fairly pronounced as the gear is bolted to the firewall ( which puts more weight on the wheels ) and the plane is a little over 60 ounces. On takeoff even on grass, it does hop if I don't let it go straight. It really wants to go straight when released from the stooge. The wheels are straight ahead, and I will be giving them a tweak to the left. It should help, and It pulls so hard on takeoff anyway that it might even mitigate some of that which would not hurt a thing. Thanks Bob.

[dale gleason]

I hope I'm not repeating a previous post I made.....I've been known for that trait, moreso lately than before....

Many moons ago, at a DMAA club Christmas party, Al had brought an unfinished stunter in for our "Show-N-Tell . I saw what I perceived to be a critical error, he had the wheels pointing inward. I pointed this "error" out to him and then he explained how it works:  launch the ship with the nose pointing out about the same angle as the wheels point in. Wheels roll tangent to the circle, thrust is outboard so the plane doesn't come in on you.

Same on landing: leading it just a tad keeps the nose out and the wheels are tangent to the circle.

Good stuff!,
dg

[Bob Whitely]

Okay, so far so good. As to the question about tri gear planes, the mains are
always behind the cg just as on a taildragger the mains are alwaysin front of
the cg. With this in mind if you toe in the mains on a tri gear it will make the nose of
the plane roll to the right, and that is not what we want. Therefore you angle the
main gear a few degrees off tangent to the right and the nose gear in just a
hair and the plane will roll to the left as needed. I know all this cause I have done
it more than just once and it works every time. RJ