Hi,

Until late 1930s, almost all aircraft had tail drager landing gear but from mid 1940s the vast majority of new aircraft were fitted with tricycle landing gears, what prompted this change? I know that there were aircraft with tricycle landing gear before the late 1930s and the that some tail draggers are still being produced, I am talking about the majority of the aircraft, not all.

I know the relative merits and demerits of each configuration i am just curious that what prompted that almost sudden change in landing gears configuration.

Thank you.

I think the change came about because planes became larger. Loading and unloading a tail dragger is more complicated given the fuselage is not level. Once you reach a certain size the difficulties become just too big.

Because tricycle landing gear is SO much easier and safer to use. On the downside, they are also more complicated to build and install, unlike the shopping-cart wheel found on a taildragger.

A side note: There was the Munich air disaster. Tail-draggers are less affected by snow on the runway, while the relatively new tricycle gear airplane couldn't accelerate enough.

David

Is it possible that fly-by-wire technology bring tail dragger configuration back?

Nean1 wrote:

Is it possible that fly-by-wire technology bring tail dragger configuration back?

Why?

Don't get me wrong, most of my flying time is in a taildragger and I'm building one of my own... but outside of recreational flying and possibly one or two niche applications (e.g. bush flying, helicopters) there's no market for it.

Can runway length be a factor?
Something along the lines of tricycle maintaining close to zero angle of attack until rotation, and drag is minimized during acceleration, and putting nose gear down on landing reduces lift - where taildragger has high AoA at rest, and maintains it on takeoff till some velocity where there is enough lift to level airplane - and opposite on landing, where AoA and lift has to go up at some point...

VSMUT wrote:

On the downside, they are also more complicated to build and install, unlike the shopping-cart wheel found on a taildragger.

The tail dragger does add complexity/weight because the entire fuselage aft of the wing needs to transfer the forces generated when the tail wheel hits the runway. Engineers can't presume all landings are smooth so you have to build in a lot of mostly unneeded strength. On the other hand, with the tricycle, the aft fuse really needs to only support its own weight and pax/cargo. By the time you get to the tail the structure is minimal, whereas on the tail dragger it's not. Consider how much force must be exerted when a tail dragging cargo plane like C-47 lands heavy. It is significant.

I know from my time with tail dragger glider tugs (Pawnee, Birddog) that the tail wheel was always a concern with regard to corrosion (since we landed at muddy grass fields) and heavy landings. I've seen Pawnees have to get their aft structure re-built due to corrosion and the pounding they took being landed by pilots of varying levels of tail wheel experience.

Revelation wrote:

The tail dragger does add complexity/weight because the entire fuselage aft of the wing needs to transfer the forces generated when the tail wheel hits the runway.

And for a tricycle gear the fuselage in front of the wing doesn't have to be capable of transferring forces from the NLG?

Wacker1000 wrote:

Revelation wrote:

The tail dragger does add complexity/weight because the entire fuselage aft of the wing needs to transfer the forces generated when the tail wheel hits the runway.

And for a tricycle gear the fuselage in front of the wing doesn't have to be capable of transferring forces from the NLG?

Good point, but I think planes are set up with weight / balance to be level so presumably the forces would be less on the nose gear. I'd be interested in hearing what others think/know.

Seems also the nose gear can allow for a lot more travel so it can have oleo/struts/etc to absorb the shock. Most tail draggers I've seen mount the tail wheel pretty rigidly because if you allow too much travel you really will drag the tail.

Revelation wrote:

The tail dragger does add complexity/weight

So why did all airplanes use it until circa 1940?

timz wrote:

Revelation wrote:

The tail dragger does add complexity/weight

So why did all airplanes use it until circa 1940?

Simplicity? Less drag in a fixed gear setup, less complexity in a retracting (main) gear setup?

As above, the switchover happened as planes got bigger. Loading/unloading freight and pax is easier when the a/c is level. It's also easier to land a trike vs a tail dragger, so safety adds to the rationale.

Revelation wrote:

timz wrote:

Revelation wrote:

The tail dragger does add complexity/weight

Loading/unloading freight and pax is easier when the a/c is ...

Good point! Anyway, in recent times we see full fly by wire technology scalling down (Airbus A-320->Embraer Phenon 450). Could this be a interesting approach to something like Pilatus PC-24, with better take-off and landing performance?

Brake hard with a tail dragger and doesn't the nose hit the ground?

No, mostly because tail draggers have awful brakes. Try using heel brakes.

Revelation wrote:

The tail dragger does add complexity/weight because the entire fuselage aft of the wing needs to transfer the forces generated when the tail wheel hits the runway. Engineers can't presume all landings are smooth so you have to build in a lot of mostly unneeded strength. On the other hand, with the tricycle, the aft fuse really needs to only support its own weight and pax/cargo. By the time you get to the tail the structure is minimal, whereas on the tail dragger it's not. Consider how much force must be exerted when a tail dragging cargo plane like C-47 lands heavy. It is significant.

I know from my time with tail dragger glider tugs (Pawnee, Birddog) that the tail wheel was always a concern with regard to corrosion (since we landed at muddy grass fields) and heavy landings. I've seen Pawnees have to get their aft structure re-built due to corrosion and the pounding they took being landed by pilots of varying levels of tail wheel experience.

The aft fuselage has to be stressed to take the loads of the tailplane & fin multiplied by various load factors and safety margins - and these loads are definitely not trivial, so I suspect in most tail dragger designs little if any extra structure is required to support tailwheel loads - except perhaps locally around the tailwheel mount itself.

I'm surprised no one mentioned visibility factors yet... I think it's far easier to taxi when you can see what's in front of you. Imagine 747 with taildraggers, the cockpit will be sitting very high in the air, you can't taxi properly.
Also, I believe because we're used to have almost neutral pitch in the ground, it must be somewhat uneasy to be at takeoff attitude when you're actually standing still.

Thank you for the detailed responses, much appreciated.

Revelation wrote:

Wacker1000 wrote:

Revelation wrote:

The tail dragger does add complexity/weight because the entire fuselage aft of the wing needs to transfer the forces generated when the tail wheel hits the runway.

And for a tricycle gear the fuselage in front of the wing doesn't have to be capable of transferring forces from the NLG?

Good point, but I think planes are set up with weight / balance to be level so presumably the forces would be less on the nose gear. I'd be interested in hearing what others think/know.

It's pretty much the same. Rough rule-of-thumb says 10% of your weight is supported by the nosegear/tailwheel, and the other 90% supported by the mains.

benbeny wrote:

I'm surprised no one mentioned visibility factors yet... I think it's far easier to taxi when you can see what's in front of you. Imagine 747 with taildraggers, the cockpit will be sitting very high in the air, you can't taxi properly.
Also, I believe because we're used to have almost neutral pitch in the ground, it must be somewhat uneasy to be at takeoff attitude when you're actually standing still.

Taxi visibility is better in nosewheel airplanes. It felt a little odd the last time I flew one because I'm so used to straining to see over the nose while taxiing. However, the nose-up attitude on ground isn't "disconcerting", at least as a pilot. You just get used to it.

Revelation wrote:

The tail dragger does add complexity/weight because the entire fuselage aft of the wing needs to transfer the forces generated when the tail wheel hits the runway. Engineers can't presume all landings are smooth so you have to build in a lot of mostly unneeded strength. On the other hand, with the tricycle, the aft fuse really needs to only support its own weight and pax/cargo. By the time you get to the tail the structure is minimal, whereas on the tail dragger it's not. Consider how much force must be exerted when a tail dragging cargo plane like C-47 lands heavy. It is significant.

I know from my time with tail dragger glider tugs (Pawnee, Birddog) that the tail wheel was always a concern with regard to corrosion (since we landed at muddy grass fields) and heavy landings. I've seen Pawnees have to get their aft structure re-built due to corrosion and the pounding they took being landed by pilots of varying levels of tail wheel experience.

But that's just complexity during construction and design On a trike you will need control linkages (possibly hydraulic) to steer the nose wheel, hydraulics to operate it and the doors, emergency gear extension plus the strut will have to be much longer too

Nean1 wrote:

Good point! Anyway, in recent times we see full fly by wire technology scalling down (Airbus A-320->Embraer Phenon 450). Could this be a interesting approach to something like Pilatus PC-24, with better take-off and landing performance?

No, it would not improve the performance. The landing performance would be severely degraded. In a taildragger you have most of the weight located aft of the main landing gear, so if you hit the brakes hard all of that weight is going to try to swing the entire aircraft around so that the tail is at the front (ground loop). It would also greatly increase drag during takeoff (less acceleration) and limit the maximum crosswind allowance.

In landing, I see the things diferently. With NLG there is a lot of weight transfer to very small front wheels, incapable to give good braking power (if any). Traildragger maybe could perform better, increasing weight to MLG, providing additional braking power.

My point is: Could modern technology (FBY for control, BBW, digital cameras improving TO visibility, CAD for structure optimization) overcome the well known Traildragger problems, giving us alternatives to a new generation of more capable small/medium size aircraft?

"Traildragger maybe could perform better, increasing weight to MLG, providing additional braking power."

1. astable arrangement COG is behind of where the brake forces are introduced.
2. overbreaking will lift the tail until the nose touches the ground. not good.
3. today you start with a low drag from lift component allowing faster acceleration to Vr
... you then create lift via rotation when it makes sense. Taildragger allows less rotation.

DH106 wrote:

Revelation wrote:

The tail dragger does add complexity/weight because the entire fuselage aft of the wing needs to transfer the forces generated when the tail wheel hits the runway. Engineers can't presume all landings are smooth so you have to build in a lot of mostly unneeded strength. On the other hand, with the tricycle, the aft fuse really needs to only support its own weight and pax/cargo. By the time you get to the tail the structure is minimal, whereas on the tail dragger it's not. Consider how much force must be exerted when a tail dragging cargo plane like C-47 lands heavy. It is significant.

I know from my time with tail dragger glider tugs (Pawnee, Birddog) that the tail wheel was always a concern with regard to corrosion (since we landed at muddy grass fields) and heavy landings. I've seen Pawnees have to get their aft structure re-built due to corrosion and the pounding they took being landed by pilots of varying levels of tail wheel experience.

The aft fuselage has to be stressed to take the loads of the tailplane & fin multiplied by various load factors and safety margins - and these loads are definitely not trivial, so I suspect in most tail dragger designs little if any extra structure is required to support tailwheel loads - except perhaps locally around the tailwheel mount itself.

Perhaps I should stop using my imagination, but I imagine that you need to build in extra strength because you must plan for the elevator to be exerting max force just as the tail slams down on the runway with maximum force.

In any case, it seems true that the main advantages are the level deck for improved loading and visibility, and avoiding ground loops due to CG aft of gear so improved safety.

kurtverbose wrote:

Brake hard with a tail dragger and doesn't the nose hit the ground?

GalaxyFlyer wrote:

No, mostly because tail draggers have awful brakes. Try using heel brakes.

WIederling wrote:

2. overbreaking will lift the tail until the nose touches the ground. not good.

Think I know why tail draggers have awful brakes - my point made.



Incidentally, I know with the early jets (certainly the Me 262) they couldn't get the tail to lift on the takeoff run. They resorted to applying the brakes to get the tail up (see above). Without prop wash there wasn't enough airspeed over the control surfaces to generate lift, hence the switch to nose gear.

Nean1 wrote:

My point is: Could modern technology (FBY for control, BBW, digital cameras improving TO visibility, CAD for structure optimization) overcome the well known Traildragger problems, giving us alternatives to a new generation of more capable small/medium size aircraft?

Well for one, fly-by-wire acts on the flying surfaces, not the wheels. On the ground (which is the most critical part with regards to tail-draggers), the flying surfaces don't have very great effect due to the slow speeds involved. What you would be looking at is an anti-skid system of some sort that can control the longitudinal direction through automatic control of the differential wheel brakes.

But ignoring that, your entire premise seems to be that tail-draggers somehow make aircraft more capable. They don't. It might work really well on a Piper Cub that gets airborne at 20 knots with a load of no more than 374 lb, but not for a several-ton aircraft that has to accelerate all the way up to 80+ knots during takeoff, or decelerate down from 90 knots with 4 tons of cargo in the rear of the cabin all rearing to turn the aircraft around through the shear force of momentum.

The takeoff issue is the same reason why aircraft don't take off with full flaps, the drag would simply be too great. They are also really difficult to operate in a crosswind. On a trike you can control the aircraft down the runway using the nose-wheel steering all the way until Vr, but in a tail-dragger you lose you tail-wheel control (if it is even controllable in the first place) once you lift the tail.

Nean1 wrote:

In landing, I see the things diferently. With NLG there is a lot of weight transfer to very small front wheels, incapable to give good braking power (if any). Traildragger maybe could perform better, increasing weight to MLG, providing additional braking power.

While that is true, you also need to maintain directional control. If activating your really efficient brakes means that you slide off the side of the runway, then it is completely worthless. See the video below.

https://www.youtube.com/watch?v=i8oqVNgA6fI

WIederling wrote:

2. overbreaking will lift the tail until the nose touches the ground. not good.

Not quite. While it is a risk, the overall biggest/most likely risk is a ground-loop. But with the raising of the tail-wheel during braking action it is closely related, and I don't really see any feasible idea to solve it.

Besides the breaking issue, it is runway length. With the ME-262, it had trouble getting the dragging tail off the ground. The design was switched to a tricycle gear from Henkel.

Before this we were seeing the transition in other high speed designs. Tricycle landing gear allows a horizontal stabilizer optimized for flight conditions. This didn't matter for prior slow designs.

There was a preference for tail draggers and open cockpits amount pilots prior to WW2. But the war forced selection of the best design. Imagine a B-29 as a tail dragger.... How? Pivoting to horizontal with the HUGE propellers would have added tremendously to runway length.

Due to the breaking issues, tricycle landing gear has fewer accidents. So during the war, training started shifting to tricycle gear frames.

It was an evolution destined to happen with jets or faster props. Trust me, you wouldn't want to be a passenger at the back of a tail dragger in the larger airframes that came out just before or during the war.

Think how much more powerful the engines were post war.

Lightsaber

Lightsaber

Perhaps the length of aeroplanes became a factor; for example, the Avro Tudor of the late 1940s.

Thank you all.

Lightsaber; Good point, maybe I was looking to the wrong place focusing in landing performance. In general, the TO distance is much more critical.
VSMUT: Crosswind still is an open issue.

Anyway, the aircraft depicted are old stuff. Modern technology will improve a lot the balance of COG (like Segway). Think about a new DHC-5 Bufallo but with front cargo doors?

Lots of interesting posts here.

DrPaul wrote:

Perhaps the length of aeroplanes became a factor; for example, the Avro Tudor of the late 1940s

.

Yep, look at that giant vertical stab and consider how hard it would be to deal with a cross wind: back side will want to wander and you have no way to control it at low airspeeds i.e. begin of takeoff or end of landing.

Some gliders I flew had swiveling tail wheels, others had fixed tail wheels. For the fixed wheel ones you simply lifted the tail or pushed down the nose as appropriate to get the glider into the right orientation before takeoff. On landing you better be aligned with the desired direction of travel before you let the tail touch down or you were going into the weeds (or rocks, etc). Rigid tail wheel not so practical with a commercial transport!

Another example familiar to those of us who watch Ice Pilots NWT:



Buffalo is still flying C-46s last I knew.

Not only is the tail a huge sail in a cross wind, so is the entire body. The pilots on the show claim it's the hardest plane to fly in regular service due to the tail dragger crosswind challenges.

Now I want to see an A380 with a tail wheel.

richcam427 wrote:

Now I want to see an A380 with a tail wheel.

Almost:



https://www.youtube.com/watch?v=7I6SSE88fF0

If you ever go to an aviation museum and walk up the fuselage of a taildragger you'll realise how boarding would be a real pain.

Some further reasons:

• A taildragger is easier to load/unload without ground support equipment, e. g. airstairs. I suppose as airports became more sophisticated, this aspect became less relevant.
• A taildragger helps to keep the props at a distance from the ground. As stronger & larger landing gear (e. g. the Starliner) became available, you could lift the entire airframe sufficiently far off the ground. Additionally, jet engines are much smaller, allowing for much shorter gear as found on most early regional jets (e. g. 737-200, DC-9)
• I believe that taildraggers work better on poorly prepared runways and muddy surfaces since the smaller wheel is being pulled out whenever it may get stuck. The front wheel of a trycicle gear will work itself into any obstacles or holes on the ground.

Take these explanations with a pinch of salt though. Although I have witnessed the operation of many taildraggers, including several vintage birds in their natural habitat, I have yet to experience commanding one myself.

I would also mention that it was evolution. Many early aeroplanes had tail skids, main wheels with bungee cords for shock absorption, and no brakes. As mentioned, prop clearance, weight, and complexity were factors that kept the tail wheel (once called conventional gear) in vogue. Brakes were added along with steerable tail wheels, oleo shock struts, and retract mechanisms. The switch to the familiar tricycle configuration was somewhat gradual. The experimental DC-4E had it as did a number of other aircraft during the WWII period. However, most of the early nosewheel configurations did not incorporate direct steering. Even the B-29 required rudder and brakes for directional control.

Lots of interesting thoughts here, but the reason tricycle replaced tail dragger is purely stability in landing ground roll and handling. WIederling touched on it with his #1 reason.
Ignoring aerodynamic forces (which become small as you roll out), a tail dragger is inherently unstable. The center of mass is behind the center of drag of the MLG. In essence, there is a force acting forward from inertial centered, roughly, at the center of mass. There is a force acting reward roughly centered between the MLG. It's easy to see if you draw it, a little harder to imaging. But the net is the aircraft wants to turn around. In a tricycle a/c, that MLG reward force is behind the center of mass. The natural tendency is to straighten the aircraft. If you get a little crooked in a tricycle gear, it straightens up. If you get a little crooked in a taildragger, it wants to turn around and you have to overcome that and keep it forward. That is why tail dragger pilots say "you have to fly it till it is tied down".

rcair1 wrote:

Lots of interesting thoughts here, but the reason tricycle replaced tail dragger is purely stability in landing ground roll and handling

I would add that it's easier to see where you're going, but safety and stability are the reason.

This is a ground loop. There's a reason the FAA insists on a taildragger endorsement on a pilot's license: your airplane would prefer to be going backwards. (caution - loud audio)
http://www.youtube.com/watch?v=3xx0pV_AUQE&t=0m45s

Random Fact: Amelia Earhart's ill-fated flight to Howland Island in July 1937 was her second problematic flight to Howland Island. In March 1937 she ground-looped her airplane attempting to depart Luke Field Hawaii for a flight to Howland Island, severely damaging her aircraft.

http://tighar.org/wiki/Disaster_at_Luke_Field

Students of history may enjoy this book, by Fred Weick, the man who invented the tricycle landing gear (among other things).
http://www.amazon.com/GROUND-UP-Fred-We ... 0874749506

I still would like to see a 737-900 taildragger edition.

767333ER wrote:

I still would like to see a 737-900 taildragger edition.

Concorde:


Saab J35

Florianopolis wrote:

Students of history may enjoy this book, by Fred Weick, the man who invented the tricycle landing gear (among other things).
http://www.amazon.com/GROUND-UP-Fred-We ... 0874749506

You find a lot of 4cycle or hybrid landing gears on German WWI "Riesenflugzeug" Bombers:
http://westhampsteadlife.com/wp-content ... bomber.jpg

don't know how one would like to tag the Kalinin K-7 gear.
https://en.wikipedia.org/wiki/Kalinin_K ... K-7_01.jpg

Could the size of the propellers have been a factor as well?

bhill wrote:

Could the size of the propellers have been a factor as well?

I don't think that really matters. DC-3 and the plane of the same era is taildragger, but the biggest prop, Tu-95 'Bear' is tricycle...

bhill wrote:

Could the size of the propellers have been a factor as well?

probably not.
During landing and take off you have the tail elevated. thus on the ground with tail down
is not the tightest constraint applicable for propeller size.
Looks like front gear as a hard limit on how far you can lift the tail would give you more room.

bhill wrote:

Could the size of the propellers have been a factor as well?

benbeny wrote:

I don't think that really matters. DC-3 and the plane of the same era is taildragger, but the biggest prop, Tu-95 'Bear' is tricycle...

Just take a look at the NLG on a Tu-95.
And take a look at the propellors just visible on the far wing; even with that lengthy nosewheel strut, those props are not far off cutting the grass.

Taildraggers like any rear axle steered vehicle are unstable. CG is behind the wheels.
If the tail goes outward you transfer translatory (forward) energy into rotation.
the tail "overtakes". rotation is upheld.

I still think they need to convert the 737 to a taildragger

767333ER wrote:

I still think they need to convert the 737 to a taildragger

Already been done

767333ER wrote:

I still think they need to convert the 737 to a taildragger

Gives new meaning to Burning down your bridges.
Was one reason to convert the Me262
going away from taildragger layout to some trycycle gears.