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Cessna 140 tail wheel Cessna 150 tricycle gear

Photos' source: Cessna 140 and Cessna 150.

According to Wikipedia here, the Cessna 150 is successor of Cessna 140. Both have two-seat capacity and a single engine.

Why was the Cessna 150 changed to tricycle landing gear from the "old school" tail wheel? If we consider that the two airplane models have the same weight and capacity, then what are the advantages/disadvantages of tail wheels vs. tricycle landing gear? Why are so few new tailwheel aircraft produced?

Note: I mentioned the Cessnas here solely because I knew their story better, so I can more easily compare them. This question should not be considered specific to only Cessna's products.

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  • $\begingroup$ Clarification please - do you intend to aim this question at light aircraft like the Cessnas pictured? $\endgroup$ – Criggie Sep 14 '19 at 22:49
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    $\begingroup$ @Criggie, not for light aircraft only,but for all size. But both the light and the heavy aircraft, all are tricycle now, right? $\endgroup$ – AirCraft Lover Sep 15 '19 at 1:35
  • $\begingroup$ @Criggie, not for light aircraft only,but for all size. But both the light and the heavy aircraft, all are tricycle now, right? $\endgroup$ – AirCraft Lover Sep 15 '19 at 1:35
  • $\begingroup$ WRT commercial planes, I'd guess that it's as much a matter of passenger convenience as anything. Consider how much worse the boarding & deplaning process could be with a tilted floor :-) $\endgroup$ – jamesqf Sep 15 '19 at 18:52
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A tailwheel is a good choice for operation on unprepared surfaces with aircraft that have low wing loading and need to be as light as possible. Two main wheels and a small tail wheel weigh less and cause less drag than a tricycle gear, especially if they cannot be retracted. On the Bo-209 Monsun only the nose gear was made retractable because, being positioned right behind the prop, it caused 40% of gear drag all by itself.

On the other hand, high wing loading aircraft with their high landing speed would need very long landing runs due to their inability to brake hard. A rejected take-off close to the decision speed would be impossible without crashing through the airfield perimeter. Braking too hard with a tailwheel configuration will cause a headstand.

To summarise the reasons given in this answer:

  • A tricycle gear offers better visibility on the ground.
  • A tricycle gear allows full brake application.
  • A tricycle gear makes loading and unloading easier because the fuselage is horizontal.
  • A tricycle gear has less drag during the initial stage of a take-off run.

Cessna simply shifted priorities between the 140 and the 150.

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    $\begingroup$ 40% isn't excessive when if balanced, it would cause 33%... $\endgroup$ – Harper - Reinstate Monica Sep 14 '19 at 22:41
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    $\begingroup$ @Harper, 40% is excessive when you realize the nose wheel is generally much smaller than the main gear. In general, a tricycle-gear plane is balanced so that the center of gravity is just barely in front of the main gear. The nose gear supports just enough weight to keep the airplane from tipping over backwards. $\endgroup$ – Mark Sep 14 '19 at 23:42
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    $\begingroup$ @Darrel Hoffman: AFAIK the main wheels on taildraggers aren't steerable. Can't say there aren't any, but the ones I've seen aren't. Even in a tricycle gear light plane, you steer as much or more by differential braking of the mains as by turning the nose wheel. $\endgroup$ – jamesqf Sep 15 '19 at 18:50
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    $\begingroup$ @DarrelHoffman: You need to run control cables to the rudder anyway, so adding a steerable tail wheel is not much of a complication. Main wheels are always not steered, and even most tail wheels (and all tail skids, obviously) are not steered, but free castering. Rudder is used to swing the tail around. On very early designs like the Blériot XI, even the rear wheel could not caster, so the tail had to be lifted up and carried around to have the aircraft point into the right direction. $\endgroup$ – Peter Kämpf Sep 15 '19 at 20:16
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    $\begingroup$ @Darrel Hoffman: WRT nose wheel steering (at least on small plane), it's not so much a question of either steering with the nose wheel or with differential braking, but of using both. If you're just rolling down the taxiway, you might be steering with just the nose wheel. If you need to make a tight turn, you brake on one side. And of course if you're moving at any speed, you still have some effective rudder. But they're all linked, and really you tend to forget about exactly what is going on - or at least I do. $\endgroup$ – jamesqf Sep 16 '19 at 20:19
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A tailwheel aircraft is particularly susceptible to a dynamic instability during landing which causes the plane to violently spin around, point backwards, and skid off the runway. This is called a ground loop and is one of the leading causes of landing accidents in tailwheel aircraft. Avoiding ground loops requires good reflexes, good training, and lots of practice.

A tricycle gear aircraft is immune to ground looping, making it easier to handle on the runway during landings.

Because the tailwheel aircraft has no nose gear, it will weigh less and experience less drag during flight than the same airframe with a nose wheel, so it can fly a little faster and a little farther on the same fuel.

However, the cost to insure the tailwheel aircraft against landing accidents is greater than the cost to insure the tricycle-gear plane, which wipes out any savings on fuel burn.

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  • $\begingroup$ Thank you for your nice explanation. It helped me understand better. $\endgroup$ – AirCraft Lover Sep 16 '19 at 14:14
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Already some excellent answers here, but to add to Peter's response, in spite of the challenges, some folks prefer tail wheel planes because they are better for back country type flying - landing on unpaved surfaces, etc. If you take a look at any of the short take off and landing (STOL) contests around the country, you see almost exclusively tail wheel planes competing.

AOPA article on STOL contests

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  • $\begingroup$ Thank you my friend for your explanation. Now I know better where it can be used. $\endgroup$ – AirCraft Lover Sep 16 '19 at 14:13
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Why was the Cessna 150 changed to tricycle landing gear from the "old school" tail wheel?

According to my old-time teacher, the accident rate in flying school changed dramatically when changing to tricycle gear. Ground loops used to be common and potentially expensive with tail-wheels. That seems to be enough of reason for a flight school to stop buying tail wheel planes. ( The 150 I believe, was mainly targeted at schools ).

For specialized uses with trained and experienced pilots, tail-wheels are still in use.

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  • $\begingroup$ I am sorry. Seems that you have misunderstood my question. "Old school" means is, "old time". So, this question is not related to flight school. But however, thank you anyway for your explanation. $\endgroup$ – AirCraft Lover Sep 16 '19 at 14:12
  • $\begingroup$ The point is that the main buyrrs of the 140 and 150 used to be flying schools. $\endgroup$ – ghellquist Sep 21 '19 at 14:35
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Conventional gear is the term that includes both tail-wheel and tail-dragger, because there may only be a simple skid in place of the tailwheel. It is simple to construct, lighter and lower cost for a given strength than tricycle.

Tricycle or nose-wheel gear. The main gear is very similar to conventional main gear it is just moved slightly behind the center of mass so the plane tips nose down instead of tail down while on the ground. But a wheel is added to the nose of the airplane to prevent it tipping forward. The nose wheel mechanism is much more complex than a tail-wheel caster, with much more mass and some inherent weaknesses on rough surfaces.

If nose gear is broken by a hole or bump on the ground the plane tips forward into the propeller, while a conventional gear plane can land with little damage even if the tail-wheel had fallen off completely. The nature of the nose down moment caused by obstacles during the landing roll takes load off of a tail skid/wheel and adds load to a nose-wheel. Also when you look at the wheel/skid path taken during a pitch change(caused by hitting an obstacle) the nose wheel tends to catch and dig in causing a huge rise in forces while a rear skid/wheel has a more stress relieving motion. As an illustration take a long pole or stick and drag one end on the ground behind you then turn around and try to push it, you see how the tip catches on everything when pushed over a rough surface and slides with little effort when pulled.

The 2 primary disadvantage of conventional gear is that the center of mass is behind the main gear which is dynamically unstable while turning on the ground. A small turn to the left wants to grow into a large turn to the left so the pilot cannot be passive and must actively correct any unwanted deviations. Any vehicle with rear wheel steering has this stability issue but sometimes the trade offs are worth it, note most forklifts and many commercial mowers have rear wheel steering.(mainly for strength and maneuvering)

The second disadvantage for conventional gear is that they cannot utilize all of the theoretically available braking friction on dry pavement, because braking force is limited by forward pitching moment, so landings and aborted takeoffs rely more on aerodynamic drag like flaps and high angle of attack and elevator down force to resist brake pitching force. On dirt and grass the maximum available braking friction is much lower than on dry pavement so the tricycle gear does not gain substantial advantage in maximum braking force. On snow or ice, tire friction is limits maximum force more than the pitching moment, and so the tricycle has no braking advantage and conventional gear is lighter and easier to fit with skis.

However, in practice with small aircraft most very short landings are unpaved surfaces and most paved runways are long enough that small aircraft don't actually need wheel brakes and pilots will avoid using the wheel brakes to reduce the maintenance costs. The braking distance issue is thus a minimal consideration for many owners. Most pilots also tend to maintain a high angle of attack during the landing roll regardless of the gear arrangement, which adds lift taking weight off of the wheels and so prevents maximum tire friction. On these aircraft the lack of braking force is somewhat compensated by light weight enabling a slower landing speed and generally less kinetic energy, further reducing the braking advantages of tricycle over conventional.

With large aircraft, especially jets, braking distance is a common issue, and they are often fitted with devices like spoilers to stop the wing from making lift and to get maximum friction from the tires right at touchdown even with a high angle of attack. These aircraft never operate on dirt, grass, or deep snow, the runways they use are inspected for holes and objects multiple times per day. The weight and cost advantages of conventional gear are minimal when adding retractable landing gear mechanisms, and the high speed drag advantage is far greater than the weight advantage of any type of fixed gear. So the advantage in this category is very much in favor of tricycle gear.

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