The easiest to "taxi" tail dragger or tricycle gear?

[eric david conley]

     After being a helper for an entrant at the last 3 NATs I'm left wondering which type of landing gear configuration is the easiest to set up and control or handle while on the ground, tail dagger or tricycle? It seems that most of the planes are tail daggers, I think because it gives the modeler more to choose from. But, I'm under my own impression that the tricycle gear might be easier to set up and control while on the ground. Are their any differences and what are some of the differences?  Eric

[Paul Smith]

On the subject of taxiing, the emphasis on ground handling is more than a little misguided.

All modern planes are in tune with the "rule book" program:  start engines in your parking place, taxi to the runway, dead stop, take off, land, taxi to parking, stop airplane, stop engines.  That's well and good to MODERN airplanes.

But take a look at WWI planes and racers.  No brakes, no ground steering, and throttles that barely worked at all.  Take a look at old films of the Howard Ike and Baron von Richtoffen.  Ground crews started the engine, aimed the plane into the wind and let go like a CL combat plane.  They came in for a landing, cut the engine and coasted to a stop.  Then they were pushed or towed back to parking.

Rules are rules.  But a Shoestring that complies with the taxi requirements is unrealistic.

[Fred Cronenwett]

I had one model where I could change the tailwheel steering with a servo so that it taxied without dragging the model in a strange way. Some smaller models will bounce if you will during taxi because it is fighting the alignment of the main wheels and the tailwheel.

I tend to align the main gear and tailwheel straight ahead it seems to work out ok. The bigger the model the easier it is to get a good taxi

I have found that models with Nosegear are easier to trim, but in the end the inboard tire wears down faster and they all scrub during taxi.

When I fly a new model, the first thing I do is a taxi test, just to make sure the model is not going to turn in on me when you apply the power for takeoff

Interesting thought about what models never do a taxi such as the Formula one racers, they are not designed to be taxied like other full size models where you can steer the aircraft on the ground with the rudder pedals.

Fred

[chuck snyder]

Eric, I have only had taildraggers for my C/L competition models, so i really can't comment on trike gear taxiing. I have noticed a problem with other guys trike gear. Depending on the prototype, some trike geared airplanes have a long nose gear--P-38, P-39, Ta-154, F-7-F. With a scale length nose gear these models will "wheelbarrow," ie., the main wheels lift off the ground before the nose wheel on takeoff. This is a major no-no with full-size. Seems like many modelers compensate by having a shorter than scale nose strut. With the taildragger you can raise the tail during takeoff, run on the mains, and lift off smoothly. With the trike your takeoff angle of attack will at a minimum be the angle the model sits on the ground.
Chuck

[Paul Smith]

Most tricycle gear planes had retractable landing gears.  If you build one of the these you are always at risk that the contest management will enforce the "no retract" penalty, which is an absolute death sentence.  Better to model a fixed gear prototype and be on the safe side.

[Tim Wescott]

Most tricycle gear planes had retractable landing gears.  If you build one of the these you are always at risk that the contest management will enforce the "no retract" penalty, which is an absolute death sentence.  Better to model a fixed gear prototype and be on the safe side.

It depends on what you're modeling -- there are quite a few civilian light planes with fixed trike gear.  They're recent enough that your scale documentation could possibly be had by sweet-talking the owner into letting you take pictures.

[Jim Fruit]

Eric:

I have found that taildraggers seem to taxi better than tricycle. With tricycles, you should adjust the nose wheel to follow the arc of the circle, not the tangent of straight ahead. Even with that adjustment, I have seen many models that try to scrub the landing gear off, making the wheels go to the outside of the circle. With taildraggers, I just adjust all to go straight ahead. The tail wheel just follows along as necessary without influencing the main gear unnecessarily. Also, as Fred said, lifting the tail wheel on a tail dragger makes it very easy to taxi.

Jim Fruit

[Phil Krankowski]

Wheel alignment does help with tail draggers.  My experience is limited to some RC. 

Slight tow in, that is the wheel alignment is set so the wheels eventually would converge in front of the model will help with straight take off runs, and tail up taxiing.  The reason is while the wheels are engaged to the ground, if the plane turns the inside wheel in the turn will want to run more free, and the outside wheel will want to scrub, effectively braking, so the airplane will tend to straighten out. 

Now a slight amount of tow out, that is the wheels would eventually converge BEHIND the airplane is a recipe for a ground loop.  When the plane starts to turn the wheel inside the turn will brake, and the wheel on the outside of the turn will run more free, so the airplane will continue turning, and turn more quickly as the turn occurs.

I would guess that by aligning the wheels to have slight tow in a manner that the convergence point is outside of the arc the control lines would make, but inside of straight ahead, that a gentle turn could be induced into a tail dragger.

Phil

[John Rist]

Both my Extra 300-S and my LA-5  have the tail wheel set to turn the aircraft out.  In operation, when taking off the the tail wheel turns the model out until the tail lifts.  Once the tail is up rudder offset turns the model out.  The trick is to hold a lot of up elevator while going slow to nail the tail wheel down.  As the speed comes up letting up on the up elevator allows the tail to lift.  Of course scale aircraft have throttle control so you control the ground speed with the throttle.  Also note the the LA-5 is an electric with reverse rotation so the motor tork tends to roll the aircraft out.  Never had a tricycle gear so I wouldn't know about them.

[Fred Cronenwett]

The 13 lb B-29 that I fly has the nose gear straight ahead and has no tendency to come in during taxi or take off. After about 15 flights the tires show no signs of wear but the model does come to a stop fairly quickly if the throttle is at idle.

I had an A-20 Havoc (nose and main gear) that wouldn't stop with the engines at idle so I had to put fuel tubing between the wheel and the collars to act as a brake (all 3 wheels) so that it could stop with the engines at idle.

The larger models, tail dragger or tricycle gear handle better as compared to the smaller models during the slow speed portion on the ground.

Fred

[Will Hinton]

Most tricycle gear planes had retractable landing gears.  If you build one of the these you are always at risk that the contest management will enforce the "no retract" penalty, which is an absolute death sentence.  Better to model a fixed gear prototype and be on the safe side.

Hmmmm, what about all those numerous Piper and Cessna etc. trike gear planes?  No retracts on most of them.
Build a 172, or a 180 Cherokee, or...   
What's my point?  There are a LOT of trike gear non-retract planes to model.  Find one of them and go for it.

[Chris McMillin]

On the subject of taxiing, the emphasis on ground handling is more than a little misguided.

All modern planes are in tune with the "rule book" program:  start engines in your parking place, taxi to the runway, dead stop, take off, land, taxi to parking, stop airplane, stop engines.  That's well and good to MODERN airplanes.

But take a look at WWI planes and racers.  No brakes, no ground steering, and throttles that barely worked at all.  Take a look at old films of the Howard Ike and Baron von Richtoffen.  Ground crews started the engine, aimed the plane into the wind and let go like a CL combat plane.  They came in for a landing, cut the engine and coasted to a stop.  Then they were pushed or towed back to parking.

Rules are rules.  But a Shoestring that complies with the taxi requirements is unrealistic.

All F1's are required to have brakes and all have tailwheels these days so in calm winds they are all capable of normal operation. So even Shoestring #16 was able to operate like the C/L rules when it was first built in '49 as it was so equipped. Rudder and differential brakes consitute directional steering in a very precise way, so this is false also. The bicycle gear airplanes used in the F1 events in the 40's were why these rules were enacted very early in the "Midget/Goodyear" era. Holding the tail on launch during a race was written out of the rules in 1970.

[Chris McMillin]

My son built a P-38 and I (very) slightly turned the mains "right" and the nosewheel "left" until I got it to taxi, take off and land without "jumping" from too much outward track or turning in excessively. This avoids what Fred was describing, it's like trimming a Stunt ship getting it right and takes a few flights. Michael could stop it by gently pulling on the lines creating a side load with enough force to overcome the forward motion at idle, release and gently walk towards it and he would be able start it rolling. This made it so he could produce a start and stop for a slow taxi very easily.  It is a 1/2A (.061) powered model but handles well. It's made from a Sterling stunt P-38 wing and tail and we were going to build another with a scale wing and tail but never did.
Chris...