The Mach Initiative.
Ingenuity in action
It’s easy to get drawn to unusual solutions.
Beware the oddly satisfying idea.
I have spent many years trying to understand how to have good ideas, beyond simply spinning on my chair, staring at the ceiling and hoping that inspiration will strike.
Few techniques that me or my colleagues employ were actually present in the syllabus of any of our degree studies. We learned most of them on the job. Therefore, we occasionally engage in a little academic outreach to feed what we have learned back into the education of young engineers.
And for this reason, I found myself standing before a team of talented young aerospace designers who pursued a goal that is both exciting and daunting in equal measure.
This team was the University of Bath Mach Initiative. A project that aims to break the record for the world’s fastest sub-25kg unmanned aircraft. The objective is to design an aircraft that will reach speeds exceeding 600 mph (Mach 0.8) at sea level.
To achieve this feat might require a little creative thinking.
I presented to the team the methods with which we are provoked to think the unthinkable.
This exposure to the Mach Initiative offers a good example of how a very slight reframing of the problem using our methods can provoke some inspired ideas from the team and yet arrive at a simple, elegant solution.
This is an important point. I enter into these dialogues not with the intention to offer ideas, but to draw ideas from the team. The point is to offer some useful tools, not to dump a pile of my own ideas before them and leave with the mistaken impression that I’ve somehow helped.
The outcome is their creativity, not mine, and this was a team already bursting with ideas.
Of note, my methods draw from Altshuller’s TRIZ and tend to focus upon the identification and resolution of contradictions. This is achieved by stating the paradox that a contradiction will introduce and then resolve the seemingly unresolvable.
With my presentation complete, we discussed the design problems that the team currently faced.
The Mach Initiative aircraft will be catapult launched, but must land upon its undercarriage to recover the aircraft.
To raise plenty of power upon launch from the catapult, the engine intake must gulp in air whilst the aircraft claws its nose up into the sky. To achieve this, the intake will typically be located on the underside of the fuselage to prevent the wing from shielding the flow.
Once the flight is complete wheels must be able to reach the tarmac upon landing.
The air intake and undercarriage both must be on the underside of the aircraft, and therefore contradict. This is a quite typical demand in aerospace design, and there are plenty of solutions to this problem which can make some compromises to locate both of these structures on the bottom of the aircraft.
However, the Mach Initiative design team were looking for a solution with a little less complexity. Their airframe is small and does not have the size, weight and power budget with which a full scale aircraft can incorporate both a retractable undercarriage and a large air intake together.
We can see our technical contradiction clearly. However, to solve this, we must define our paradox. We must find the physical characteristics that must adopt two contradictory properties.
Simply making a list of options can lead you directly to a solution. You’ll see it right away. The chain of paradox considered by the Mach Initiative team looked something like this.
- How could that intake be present, and yet also be absent?
- How could the undercarriage also be no undercarriage at all?
- How can the intake be on the underside, and yet consume none of the underside?
- Alternatively, how can the undercarriage emerge from the underside, without emerging from the underside at all?
- How could an intake on the bottom actually be on the top?
- Which leads us to a ludicrous question, how could undercarriage on the underside, actually emerge from the top?
- How can the underside also be the top…?
And in this final question we soon arrive at the psychological inertia that is hiding from us a potentially creative, elegant and obvious solution.
We are using manned aircraft as our model, and manned aircraft typically have a right side up. A manned aircraft requires this orientation to accommodate the pilot.
And yet, the Mach Initiative design an unmanned aircraft. The comfort of no pilot requires consideration. The vehicle has no need to define a top and an underside. No up and no down. Right side up and upside down have little meaning.
The aircraft could therefore adopt one way up on launch, and yet fly inverted during landing.
Perhaps the intake could be located on the underside during its initial climb after launch, and yet also be found on the upper side during the landing run when the engine is idling or entirely inactive.
Similarly, perhaps the undercarriage could be located on the underside during landing, and yet also be found on the upper side during launch from the catapult, retracted inside the fuselage, but inverted.
The technical contradiction between intake and undercarriage are therefore separated in both space and time. These structures could adopt two entirely different locations on the aircraft, and yet both are oriented correctly when in use.
Neat? Simple? Satisfying?
Maybe. Maybe not.
As ingenious and unexpected as this solution may be, that’s not the lesson to learn here. A great idea begins as mere novelty. After all, a great idea has a sting in its tail. To have a great idea will make you feel really good. To become unburdened from a problem by a good idea can completely halt any further inspiration.
The actual hard work and the truly elegant solution to this contradiction evolved later, once I had long left the building. This was my objective, after all. To give the team some simple tools and let their ingenuity reign.
This ostensibly ingenious and elegant solution hid many Benefit Induced Harms. This is a common outcome of an ingenious idea. We think we’ve developed a clever idea only for it to be accompanied by numerous brand new problems.
If we become enamoured by our ingenious idea we may be inclined to ignore these new problems, or perhaps may spent precious time and money firefighting each new problem with yet another ingenious new idea. And the more effort this requires, the more this justifies digging ever deeper into this hole.
With clever, satisfying and ostensibly elegant ideas, you may hold on tightly, but must let go lightly.
The Mach Initiative airframe is optimised for high speed flight and doesn’t fly particularly well upside down. To ensure good control during inverted flight we must lose some of that high speed optimisation or risk an uncontrollable airframe. We succumb to the compromise of a Benefit Induced Harm.
To fly well in either orientation requires a flight controller that can. More complexity is introduced by a Benefit Induced Harm.
Furthermore, this behaviour would require two GPS modules to determine our location, each facing in opposite directions. More weight. More complexity. Another Benefit Induced Harm
Both GPS modules will require calibration upon take-off, somehow. Another Benefit Induced Harm.
Just because an idea seems elegant and makes you feel good, doesn’t mean it is not full of practical harms that will kill your idea stone dead. We could chase all of these solutions, but we’re still in the concept design stage. We can make another attempt for an elegant outcome.
It takes a mature approach to engineering to discard an idea that once delighted. This is the lesson to draw from this example.
Hold on tightly.
Let go lightly.
Take another stab at it.
See where it takes you.
From which psychological inertia are we suffering that is forcing us to pursue an airframe that flies both upside down and the right way up? That we cannot climb out from launch with the intake on the top?
It’s a reasonable assumption, borne out by the arrangement of most other aircraft. Fewer have the intake on the top, unless forced to.
It’s a decent assumption, but do we have any evidence that this is true? Subsequent tests upon the Mach Initiative engine with the inlet attached found it far more resilient to stall at the launch angle of attack. A psychological inertia is resolved.
This leaves us with the intake on the top, and so the undercarriage can be on the bottom. The contradiction is banished. No compromise must be made. The problem is solved.
Are we finished?
We arrive back at square one, but we’ve picked something up on the way. We still have those paradoxes to consider.
- How could undercarriage also be no undercarriage at all?
This is a paradox worth considering, as anything that isn’t engine or an aerodynamic structure is unwanted weight that hinders the aircraft’s performance.
We could lean into trimming some structures and merging others, two more common and useful principles from TRIZ. What if we employed no undercarriage at all? The sleek aerodynamic profile becomes the landing gear, without added weight or protrusions. The landing gear no longer hinders the aircraft’s ability to have the biggest possible engine in the smallest and most aerodynamic profile.
This leaves the intake on the top, and a simple skid on the bottom. The intake on the ‘wrong’ side, and removing the undercarriage altogether is the elegant solution.
If we’ve exercised our methodology well the solution shouldn't be wild or crazy or unorthodox. Great design is not great because it’s different just for the sake of being different. It should be obvious.
The elegant ideas should always be obvious, but sometimes only in hindsight.
Neat. Simple. Satisfying.
But most importantly, rather than simply copy what has come before, you must understand why.
