Tricycle Landing Gear Construction

[Talon Driver]

I am builing a Park Flyer around a 44 in wing. The previous aircraft had a tail wheel and had a heinous tendency to ground loop.

Nonetheless, I want to build this new version with a tricycle landing gear.

I understand trickes are easy to takeoff but can be tricky to land.

To make the the tricke easier to land should the nose wheel be shorter than the main landing gear?

Current mains are going to be about 14 inch wide and about 5 inches high.

I know making the nosewheel higher facilitates takeoffs and shorter hinders T/Os

Will making the nosewheel on a tricke shorter make it easier to land?

Cheers,

Chuck

[steve lewin]

I wouldn't think a parkflyer would be hard to land anyway, trike or taildragger. But no I don't think a low nosewheel will help your landings, it will just cause you to dig in and tip over. Stick with the undercarriage fairly level and learn to flare on landing (easier to say than to do I know, I still nose 'em in from time to time).

BTW I don't know what surface you're flying from but I've usually found taildraggers very easy to take off from grass. IMO it's only on very smooth surfaces that trike gear makes much difference.

Steve

[Viper Pilot]

The best T/O and landing plane I ever flew was a low-winged tryke (Hanger 9 Advance 40 glo).

It has an ever so slightly nose-down attitude and was the only plane that would literally land itself after the glide angle was set properly.

Don't know if this will help, or get flames, but this is my experience.

VP

[Sparky Paul]

With tail draggers, the main mount should be located so the front of the wheels can be seen when looking straight down past the wing leading edge.
A forward wheel position causes those ground loops, and it can be exacerbated by a steep ground angle (ala Dr-1).
My tail draggers take off like they're on rails. No steering required once the tail rises.

[Talon Driver]

Originally posted by Sparky Paul
exacerbated by a steep ground angle (ala Dr-1).


What is a steep ground angle?

Chuck

[Sparky Paul]

Here's one.
Cubs have the same problem..

[Talon Driver]

I take it from the photo "steep ground angle" is the angle between the longitudinal axis and the ground when the aircraft is at rest on flat ground.

Cheers,

Chuck

[Talon Driver]

Originally posted by Sparky Paul
...A forward wheel position causes those ground loops, and it can be exacerbated by a steep ground angle (ala Dr-1).
My tail draggers take off like they're on rails. No steering required once the tail rises.

Help me out here. Initially I thought on a tail dragger the mains forward of the wing leading edge is good.

However, in above thread you expressed "A forward of wheel position causes those ground loops."

Please elaborate.

Cheers,

Chuck

[Bill Glover]

The further forward the wheels are the more directionally unstable it becomes (but the less likely to nose over). A trike is a little more directionally stable because you have the drag/friction of 2 wheels behind the CG and 1 in front (rather than 2 in front with a taildragger).

Lining the wheels up vertically with the wing LE is a 'rule of thumb' that normally gives a good compromise between keeping straight and nosing over.

But there are other factors such as ground angle (already mentioned) and tail moment - a short-coupled plane is much more twitchy on rudder than one with a long fus. as there's less damping at low speeds.

[mralston]

Chuck,
Try replacing the tail wheel with a wire skid. I found that my park flier didn't groundloop as easily with a wire skid. I guess the added drag stabilizes things. It's lighter too.
Mark

[Talon Driver]

Bill,

You make a great deal of sense. Thanks for the concise advice.

Cheers,

Chuck

[Talon Driver]

Originally posted by mralston
Chuck,
Try replacing the tail wheel with a wire skid. I found that my park flier didn't groundloop as easily with a wire skid. I guess the added drag stabilizes things. It's lighter too.
Mark

I no longer have this tail dragger. However, it originally had a skid. The skid guaranteed the acft to ground loop everytime I got any bank angle during T/O. I went to a tail wheel and this resolved the problem.

Nonetheless, with the tail wheel the plane would routinely ground loop in the final stages of landing roll.

I really think the problem was I had too steep an angle between the longitudinal axis of the acft and the ground.

My original thread entry was to query should a trike have a nosewheel slightly shorter than the mains.

That is on a level surface should the longitudinal axis be slightly down, i.e. about 2 deg.

Thought was this would prevent riding on the nose wheel if I were not to get a good flare.

Cheers,

Chuck

[Bill Glover]

One important thing for a trike is that the mainwheels are only slightly behind the CG (ideally the plane should just rock back level if you push the tail down). This is so it can 'rotate' easily to a slight nose-up attitude as it reaches flying speed on takeoff.

A nose-down u/c attitude (short noseleg) will make landings "positive" (much reduced chance of bouncing), but is bad for takeoffs. The plane will never fly off on its own, so you have to haul 'up' ele. Normally by this time the speed is higher than needed so the plane pitches up sharply, not very elegant! Similar results with the mainwheels too far aft. Both these configurations are OK if you always handlaunch, but IMO learning to get the speed just right on landing is one of the most satisfying things in r/c flying - a perfect touchdown right in front of the pilot takes a fair bit of skill! After nearly 30 years I still love doing touch & gos .. which is why my Twin Star has a trike u/c!

HTH.

[Talon Driver]

Thanks for the data guys. I have been doing some design iterations using Real Flight G2. Actually this is not to bad a way to make changes to a model and then see what happens.

I notice that for a trike, if you place the mains just behind the CG you obviously are easier to rotate. However, it sure makes the landings more dicey. Placing the mains further aft makes the nose gear less sucseptible to PIO on landing, however it starts to make it more difficult to rotate.

I think I found the sweet spot for my given model. It is about 2 lbs total the main wing has an 8 in chord. The CG is 2.25 in behind the leading edge and the mains are 2 in behind the CG. With a Mega 16/15/4 geared to 2.5 turning an APC 11x7, should make a great trainer/park flyer with monster get up and go!

Cheers,

Chuck

[Sparky Paul]

Setting the mains so the plane will just rock back to level when the tail is pushed down is about correct for a trike.
On my Team Kadet it will sit on the fuselage tail when I push it down.. this is because I taxi sometimes dragging the tail. :D
Placing the mains too far aft results in a zoom climb on rotation becaues of the excess elevator to pull the nose up.

[Bill Glover]

BTW, if you get the main gear position right you can normally taxi a trike with a fixed noseleg pretty easily. Hold full up to take as much weight off the nosewheel as possible, then use throttle & rudder to steer.