Cessna 172 vs Diamond DA40NG – Which offers the best training aircraft?

I would wager real cold hard cash that when somebody thinks of a single engine piston GA (General Aviation) aircraft that pilots take to the skies in on their journey to become a pilot, the first thing that comes to mind is in the shape of the tried-and-true Cessna 172 (C172). The high wing piston single engine powerhouse that has graced the skies and aerodrome ramps for the last 69 years! I’m sure almost all the current pilots reading this article have found themselves at the controls of some variant of the C172 along their piloting journey. 

But time marches forward, and with it, as does aeronautical knowledge and technology. This means we are seeing a slew of new aircraft making their way into the skies and onto aerodrome ramps world-wide. This new aeronautical technological onslaught sees new opportunities for flight training organisations to potentially modernise their aircraft training fleets and look to offer pilots in training new experiences and methodologies that may be more in line with 21st century aviation thinking and process.

But is it a foregone conclusion that all new pilots will now see their training time behind the centre stick of a Diamond DA40 rather than the control column of a C172? Maybe. Maybe not. This article sets out to explore the differences between the old but mighty C172 and the new and impressive DA40 from my firsthand experiences with both aircraft. 

So. What’s the difference?

Looking at both aircraft side by side, they couldn’t appear more different. Aside from the single centreline propeller, there is very little to marry the two aircraft together. The Cessna 172 is a high wing aircraft with a traditional vertical tail with two horizontal stabilisers jutting out below it. There are two traditional doors, just like your family car, allowing access to both sides of the passenger cabin. Once inside, your seats slide forwards and backwards on rails. You can tip the backs of those seats forward like a two-door coupe to allow you passengers into the rear bench seat. Once inside and seated, you have that traditional control column to greet you begging you to take a grasp with both hands (but just one please) and prepare to take to the skies.

Compare this to the sight of the Diamond DA40. This is a different beast. It’s sleek, low wing design strikes an immediate feel of the contemporary. The bubble canopy sleeks itself rearward into a thin, aerodynamic empennage (that’s the back part of the aircraft) that then flows upwards into a vertical stabiliser. But those horizontal stabilisers are now sitting atop that tail (called a T-Tail), rather than below. Gone are the traditional doors allowing you access to the passenger cabin, replaced by a canopy that raises up on forward hinges like an F-35. Stepping up onto the wing and then down into the pilot’s seat, you are greeted with a centre stick rather than that traditional control column. It’s okay, grab that stick and take yourself into 1986. Now you're Maverick. Instead of sliding the seats forwards to allow your passengers into the back, they have their own gullwing door behind the cabin to let themselves in. That seat you’re in doesn’t move either. It’s attached to the floor, and the rudder pedals come to meet your feet with the push of a button.

 As you can see, the designs of these two aircraft couldn’t be more different. But is it all skin deep?

No. Under the skin, these are two very different aircraft.

It’s not just the looks that set these two aircraft apart, but the design underneath the exteriors present a sea of differences also.

Let’s start again with the C172. Designed and built in the USA, the construction of the aircraft is riveted aluminium. This harkens back to the technology of its era. Designed in the mid 1950s, aluminium was the perfect choice for aircraft construction. It is light and machinable allowing for a metal aircraft construction light enough to achieve the desired performance and keeping the aircraft easy to produce. One downside to this construction comes in the form of the rivets that exist all over the airframe to hold all of that aluminium together. These little rivets stick out into the airflow when you’re flying and produce parasitic drag. While this won’t affect your performance too much, it is a by-product of this older style of aircraft construction. Underneath that skin is a skeleton of sprues and spars forming the famous basic shape. The control surfaces (ailerons for roll, elevators for pitch and rudder for yaw) are connected to the pilots control column and rudder pedals through a series cables and pulleys allowing for aircraft control. Those high wings above the cabin are constructed with a single spar connected to a wing strut helping with rigidity and strength. Inside each wing you will also find an integrated fuel tank feeding the power-plant. Up the front we find a traditional AVGAS burning piston engine. The C172S variant that I fly is powered by a Lycoming IO-360-L2A power-plant. This is an air cooled horizontally opposed four cylinder naturally aspirated engine producing 180HP. This turns a fixed pitch two bladed aluminium propeller. The power-plant is controlled from the cockpit by a black throttle lever (RPM) and a red mixture control (fuel mixture).

Now, looking at the Austrian designed Diamond DA40NG. When designing this aircraft in the mid to late 90s, the primary mandates were to design a modern and safe general aviation aircraft that brings this segment into the upcoming 21st century. To that end, the construction of the DA40 is entirely from composite materials. This allows for far more aerodynamic designs that are completely smooth (no more rivets!) and very strong. Composites are the aluminium of the current aviation design world and the DA40 is a fantastic representative of this new philosophy. Rather than sprues and spars comprising the skeleton of the aircraft, the glass fibre-reinforced plastic (GFRP) composite fuselage wraps a shell of GFRP bulkheads and stiffeners. While the rear control surfaces are engaged by a similar cable and pully system to the C172, the ailerons at the ends of the wings have a direct push-rod connection to the control stick. This means that the roll control of the aircraft is extremely direct and responsive, even in the stall. One part of the safety story of the DA40NG is the 26G rated passenger safety cell to help protect the aircraft occupants in the event of a crash. The design of the wing spars is another key feature of the aircraft that not only helps with the strength and rigidity of the airframe, but also contributes to the safety story. Down the length of the wings are two thick wing spars separated by a cavity. Within that cavity in each wing is housed a bonded aluminium fuel tank. These spars protect the fuel tank in the event of an accident to prevent fuel spillage and greatly reduce the risk of a post-crash fire. The fuel housed in these tanks is different as well. This is because up the front of the aircraft is a liquid cooled, Jet-A1 burning Astro AE300 turbocharged common-rail injection diesel engine producing 168HP. This turns a variable pitch three bladed composite propeller. The engine and prop are controlled from the cockpit by a jet like, electronically managed single lever control system. 

So what’s the same?

While there are so many differences between the C172S and the DA40NG, there are some things that remain the same. Firstly, they both have tricycle landing gear (a nose wheel and two main wheels). Secondly, the avionics. Most C172S variants you come across, especially those at flight training organisations, will be equipped with Garmin G1000 avionics. This all-glass (digital screens) avionics package represents the new standard in avionics for general aviation aircraft.  It stands to reason then that you find the same G1000 avionics suit in the Diamond DA40NG. This allows for some positive transfer going between these two aircraft and learning primacy moving into larger aircraft later in your career. Both aircraft also have traditional lap-sash seat belts like those found in your car and come with a set of keys to unlock the doors or canopy and start the engine. Both of these aircraft also offer the same exhilaration and inspiration of flight.

What are these aircraft like to fly?

Let me start by saying that I believe both aircraft handle very well. They are both very stable and responsive to pilots inputs and are very forgiving. With that said there are some very key differences.

Let’s start on the ground, before we even get airborne. The C172S has a traditionally steerable nose wheel connected to the rudder pedals. Therefore, to turn the aircraft left or right on the ground, you depress the rudder pedals in the direction you want the aircraft to go, and it begins to go in that direction. The DA40NG on the other hand has what is called a free-castering nose wheel. This means that the nose wheel is not directly steered by the rudder pedals. Instead, the pilot uses the brakes of each main wheel differentially to steer the aircraft. This means that to turn right for example, the pilot must put pressure on the right brake pedal (above the rudder pedals) to steer the aircraft right. This can be slightly  more challenging for new pilots to get the hang of and offers a steeper learning curve than that of the C172. This also means that you need to carry more speed on the ground to maintain positive directional control.

Now, into the air. In the C172S, when you climb away from the runway towards your desired altitude, you adopt a higher nose attitude (the picture out the front of the aircraft) to achieve your desired climb performance. One notable difference I found in the Diamond DA40 is that this climb attitude looks a lot lower than the C172S. This is fantastic for forward visibility but does feel unusual if you’re used to the high winged C172S. Once you start manoeuvring these aircraft around the skies, you realise that they are very similar, but the DA40 seems more direct in its handling and a bit more ‘solid’. I found the DA40 a very easy aircraft to settle into steep turns and other manoeuvres and very little trimming is required to achieve a wonderfully trimmed state.

One of the biggest differences in air working manoeuvres I found was in the Stall. The C172 stalls very well. It is a benign nose pitch down moment in a clean, balanced stall which is easily recovered with forward control column input and power. Even when stalling in an unbalanced state and experiencing a wing drop, the recovery is easily executed and normal flight resumed. The DA40 is VERY different. In fact, if you didn’t have the stall horn going off, you would barely know the stall has occurred. With full back-stick input at idle power the only indication of the stall is a steady 1000 feet per minute descent rate and the aforementioned stall warning. If you’re waiting for that nose down moment to occur, you better bring a good book because it just doesn’t happen. At least it hasn’t in my experience. Even in a descending turn, with full landing flaps the only real indication of the stall was some control buffet. The DA40 is a VERY stable aircraft in a stall.

What about in the Circuit pattern?

A large portion of a pilots ab-initio training will occur in the circuit pattern practicing take-offs and landings as well as just flying that rectangle all pilots know so well. The two key differences between the C172S and the DA40NG in this regard come down to airspeed (how fast everything is happening) and how they land.

The wonderful thing about the C172S, and a big part of the reason it has been such a solid training platform for so long, is that it can conduct all its manoeuvres at relatively low airspeeds. For example, coming in to land the C172S will cross over the runway threshold at 65 knots with full flaps. This is a very a manageable speed for a low hour pilot to allow them to come to grips with the landing phase and getting back down on the ground.

The DA40NG offers a little bit more of a challenge. When bringing the DA40NG in to land, you will cross the runway threshold at 77 knots with landing flaps. This can represent a challenge to low hour pilots as the time allowed for decision making and reactions is reduced. This is not to say that a low hour pilot cannot keep up with a DA40NG but, like the free-castering nose wheel, it offers a steeper learning curve.

What about landing?

As I mentioned, the other big difference is in the landing phase of each aircraft.

The C172S landing phase consists of a defined Round-Out --> Hold off --> Flare. Well, all aircraft do really, but the process is very pronounced in the Cessna. And because the C172S comes into land at that lower airspeed, the pilot can keep up with this process more easily. As you come to your round out height, you reduce your power to idle and apply back pressure on the control column to raise the nose into a straight and level attitude (the picture outside the front of the aircraft, remember?) and keep the aircraft flying. Now you’re in the hold off. While you wait for the aircraft to stop flying and want to land, you will apply more back pressure on the control column to raise the nose more and more. This is now the flare. The goal is to adopt a landing attitude (glareshield on the horizon in the C172) to allow the main wheels to touch down gently on the runway first, followed by the nose wheel. Landing a C172S is considered challenging and something that takes many flying hours to master. 

Compare this to the DA40NG. The process of landing the aircraft is the same, but plays out very differently. Firstly, we come over the threshold at that higher airspeed of 77kts. This means the pilot has to work harder to stay ahead of the aircraft. The next difference occurs at the round out as the height above the runway seems a fair bit lower than in the Cessna. Now, again, you’re in the hold off. This phase takes much longer as those low, long wings keep the aircraft in ground effect (think of it as a cushion of air underneath the aircraft at low altitudes that wants to keep it flying). This is called float, and you just must be patient with it. Finally, the flare is far less pronounced in the DA40NG as you don’t require much of a nose high landing attitude. In fact, the DA40NG lands quite ‘flat’ (on all three wheels at once) compared to the Cessna. 

While both aircraft offer a challenge in the landing phase, I believe the Diamond offers a slightly greater challenge because of the higher approach speeds, greater propensity to float and flatter landing attitude.

So, which is better to learn to fly in?

We’ve come to the million-dollar question. Between the Cessna 172S and the Diamond DA40NG, which is the better aircraft for your flight training journey. In my opinion, the answer is… it depends. 

In terms of an ab-initio flight training aircraft, I would recommend the Cessna. It offers a wonderfully stable platform that allows enough of a challenge in upper air work manoeuvres (Steep turns, stalls) along with granting lower airspeeds in the circuit wrapped up with a challenging landing that will set any pilot up with fantastic foundational skills.

But if you want to take your training and skills to the next level and look towards flying those bigger aircraft later in a commercial flying career, the Diamond DA40NG is the platform I'd recommend. It’s handling and landing characteristics are perfect for adding to and improving a pilots skill set. And the advanced jet like engine and throttle management mimic what professional pilots will experience later in their careers.

This is not to say that you couldn’t fly a Diamond DA40NG from day one of your pilot training or fly a Cessna 172S deep into your commercial training, but in an ideal world I believe the above solution would be ideal. The best of both worlds.

Edward is an accredited Flight Instructor at RMIT Aviation Academy at Point Cook, Victoria, Australia and volunteer pilot for Australian Air Force Cadets.