Originally Posted by
FlightDetent
Cons of the other suggestions, as picked up over the forums here1:
strakes
- Very badly predictable in the design stage. You do not know what it does unless you flight test it. Single engine, side slipped flight at high AoA with ice on them and only one gets a hot air blast the exhaust,? A/C departs controlled flight to the side. Unpredictable risk on the development scope and amount of effort. fdr's stories on fast jet nose section design speak volumes.
- Adding weight and drag penalties, no matter how small amounts, does count (for some). The largest customers do care, rightfully or not their Excels are sharp and furious.
- Extra maintenance requirement for inspections over the lifetime of the airframe. Cost, costs, costs... customer choice, customer choice, customer choice
- Increased risk of ramp collisions. IDK but any object with mass has its own gravity and on the ramp EVERYTHING gets hit eventually. New repair schedule, new DDG items... oh.
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Strake flow effects are very predictable, with respect to core, rotational moment and stability. Additionally, interaction of a vortex flow with flow around an arbitrary body is quite accurately projected. It’s not that hard, I do it freehand, and get the same output as the Cray would over a couple of months of DES runs… can’t agree with your assertion, but I’ve only been doing flow visualisation since 1970, as a kid.
The drag of a single TBC VG is by recollection 0.0002 units, so, yes, they do add drag. They also can reduce drag by about 100 times their own drag count where there is a flow control benefit, so, not sure I concur.
Funny thing about aero mods, apparently it is assumed that they need to be of iron or steel or at least aluminium. That is in spite of the certain knowledge that an air jet with modify a flow field, and oddly for the last 30 odd years, I worked with elastomeric materials and other soft structures as I was both cheap, and having a desire to play with blades, didn’t have a death wish. In 2007 I flew elastomeric materials as a tab on a helicopter rotor, having done the same on propellers for 13 years previously. The argument on ramp rash doesn’t end up having validity when the devices are able to be squishy stuff. Just my opinion though. The materials required are high tech, you have to be able to find an Ace Hardware at least, or an Auto One, so, yes, there are technical hurdles.
Originally Posted by
FlightDetent
trailing edge mod on the wing or elevators
- Completely out of scope, design frozen, signed and dusted for. The simple little issue needs a simple little solution. Constant re-tweaking kills projects like nothing else. And why touch the wing unless you absolutely have to? You don't. Sure, for the MAX+ at 2028 it will be done.
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? have you heard of Part 21?
Originally Posted by
FlightDetent
stick pusher AS WELL AS artificial feel unit mod
- certification review of the F/CTL system
- training required, commonality tanked
- extra weight
- messing with what works never goes without problems. Probably best they did not - geez these guys failed to connect the AoA light and could not see MCAS acting on the sole most powerful aerodynamic control is class A critical item like no other.
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The stick pusher is actually not a cure for the issue, it avoids one of the undesirable states, but does not affect the stick force gradient that is the underlying irritant. If one was employed, refer to the bean counters lament re runway/payload loss. The B747 never required a stick pusher, putting an extraneous safety device on an aircraft due to ignorance is not the hallmark of excellence. 747s stall very nicely.
Originally Posted by
FlightDetent
MCAS
- a software routine, simple to model and dry test
- easy to update and change later across the global fleet
- does what needs to be done
- does not involve touching any of the existing systems that have been time-tested to perfection
- no extra hardware
- no additional training as it really is just an additional spinning mode for what the STS actually is - an autonomous THS compensator.
Yet, after all, the very same teams who understandably chose the proper way out is with MCAS against the hard options, could not avail themselves to just doing anything but simply admit a less than perfect force characteristics on the control column. The EASA boss statement is inconclusive. Various otherwise dangerous aeroplanes (not the case of MAX) can be flown safely if you know how to do it.
I think Peter Ladkin and the gang
at the RVS Group (AG RVS - Arbeitsgruppe Rechnernetze und Verteilte Systeme) at U Bielefeld may disagree. Would be an interesting conversation though.
A thought in passing: We live in a world that we establish heuristics that are functionally linear as that is what we can comprehend as analogs of complexity. The world however is stochastic, and we are set up by our very nature to have bad days as a consequence. Our own behavior is anywhere from logical to emotional, and the complete spectrum in between. We do not think linearly at all, yet we attempt to model the world in that way. The variability and non-linear manner that the human conducts cognitive functions gives the ability to achieve creativity, which helps when we get situations that give divide by zero outcomes. More often than not, it is the human's ability to cognitively function in conditions of uncertainty, using our innate fuzzy logic, that permits a solution, a save, or creativity to occur. It was the human variability in September 83 that saved the planet from a , man-made destruction,
Stanislav Yevgrafovich Petrov (Станисла́в Евгра́фович Петро́в) saved the whole damn planet, and he passed away in near anonymity in 2017, "I was made a scapegoat". He stands alongside Captain Vasily Arkhipov (Василий Александрович Архипов) who refused to fire a nuke torpedo during the Cuban missile crisis. Arkhipov had been on the Hotel I K-19 previously during the reactor casualty event, under the command of Captain Nikolai Zateyev (Николай Владимирович Затеев). A couple of years later, on a Foxtrot DE SS, B-59.
Arkhipov and Zateyev both died of cancer, 10 days apart; the Hiroshima class was an apt name for the Hotel, Echo, and November boats of the USSR.
Perfect systems... like Chernobyl, 3 Mile Island, Fukushima...