Similar, yes, but the data already exists.Diadem wrote: ↑Tue Jan 15, 2019 12:06 am No, it's very much a similar discussion to the one we're having: an airplane won't bend as soon as the MTOW is exceeded by one pound, the maximum weight limit is set at some point that the manufacturer thinks the performance of the aircraft will be adequate, usually factoring in engine-out performance. The performance is highly unlikely to be degraded significantly one pound over, it probably won't happen a hundred pounds over, it might not even happen a thousand pounds over; the point is that you don't know because the manufacturer didn't test it. By your logic, we should have every aircraft tested to find out at exactly what weight and atmospheric conditions the performance will no longer be acceptable, just to show those pilots who are inclined to fly overweight how bad it would be.
With the exception of the 12500 lbs limit, that is already calculated in to detail. Once you exceed MTOW your safety margins in other areas -damage from turbulence, hard landings, structural fatigue, take off distance, single engine performance, ...- will decrease. I don't think we can know how many pilots take off overweight, but we do know that the amount crashes where being overweight is a major factor are -luckily- very rare. More research in this area is, for me, therefore not necessary. Every question that you have about that, could already be answered by the manufactureres, if their lawyers would let them.
That is why I specifically mentioned planes of the Caravan / PC12 generation and newer, which, I assume, exist digitally. Maybe even the recent model king airs. If you start with that today, a big part of the fleet will be covered, and the percentage of airplanes that have the numbers will only increase. It would probably be cost prohibiting to develop a full 3 D model for something like a DC3. Although, maybe the basler conversion already has a model like that, I do not know.Diadem wrote: ↑Tue Jan 15, 2019 12:06 am For modern airplanes, you might be able to approach the manufacturer and have them provide complex computer models, but do you not realize that those models don't exist for things like Navajos and Otters that have been out of production for thirty or forty years? The Q400s and 737s aren't the ones taking off contaminated, so it doesn't even matter if you can get models for them. You're going to have to get 206s, Conquests, Beech 99s, and all the other outdated pieces of crap from up north that are the ones being flown contaminated, collect every single tiny little piece of data on every version of those aircraft with every engine, every propellor, every STC, in every configuration, for every phase of flight, and then figure out how icing affects them.
Who the hell is going to pay for that?
You can accurately calculate/simulate the effects for certain predefined cases. And you know it is just frost or clear ice, because that is what the predefined case is. Where the uncertainty will arise, is when you show up to a plane and you don't know exactly what standard configuration matches with the plane. If any. Ok. Let's say you look in the provided data, and you find 3 possible options that you think match the situation. That gives the pilot 4 options: don't go, or go with possibly a 4000 lbs penalty over MTOW, or a possible 2000 lbs penalty or a 3000 lbs penalty, based on the estimated condition of the airplane, I hope at least a significant amount of pilots will choose for the no go option.Diadem wrote: ↑Tue Jan 15, 2019 12:06 am I don't think you've read a single thing that's been written here. You can't boil down icing to "frost", "clear ice", "mixed ice", and "whatever". You're oversimplifying things to the point that any models you make will be utterly pointless. You have to have data for every single combination of types of icing, that accumulates both on the ground and in the air, and you have to be able to accurately measure the thickness. Otherwise it's no better than eyeballing the conditions, and that's what people are doing already.
Regarding your remark about the multiple layers: that probably indicates there is a huge amount of ice on the plane. So much, that even today, I doubt any pilots would dare to take off. But even if they are using the data and contemplating a take off, any possible contamination they will try in the chart, will show that you are taking off with severe weight penalties.
Another reason why research would be interesting, would be to determine how 2 layers of different ice would interact. Intuitively, I would say the friction index on the top layer is important, and the weight of both layers would be a factor, but yes, there could be unexpected effects. One more reason to learn and investigate.
I'm not asking anyone to go blasting off with ice on the wings. Use the models, simulate the ice build up, and publish the results. The document you linked to mentions the wind tunnel experiments, but only for the effect on the fluid as far as I can tell.Diadem wrote: ↑Tue Jan 15, 2019 12:06 am There isn't much data on the effects of ice on top of a wing on take off, because even NASA test pilots don't want to go blasting off with a sheet of ice on the wings. That should tell you something. Anyway, most of the studies I've found discuss in-flight icing, which apparently isn't relevant to you, or are behind a paywall, so here's a publication from TC that has some very detailed information, including wind-tunnel data: http://publications.gc.ca/collections/c ... -2008E.pdf
The pilots don't claim they know better than the experts, because the experts don't say what the problem will be. How can you trust the experts if they claim a 1 inch wide strip of thin frost just behind the leading edge is as deadly as a plane covered in 1 inch thick sheet of solid ice? There is no distinction at the moment to show the difference between those situations. Is the 30/40 rule applicable to 1 inch line of frost, or to the 1 inch of solid ice?Diadem wrote: ↑Tue Jan 15, 2019 12:06 am there's no point in presenting data to someone who is convinced the data is stupid and the experts are just living in ivory towers. It doesn't matter if you show them data that is slightly more forgiving than what they're expecting, because they don't care about the numbers; they "know" the aircraft will fly, and they'll keep pushing limits until they don't get away with it anymore.
While I do not condone it, I can understand that a fatigued pressured pilot without any deicing equipment flying with an empty turboprop could be tempted in the middle of the night to illegally take off with a bit of frost behind the leading edge. On the other hand, if you told him this would put him 2000 lbs over the MTOW, then I hope that pilot would not even think about attempting a take off like that.
That is what I would like to achieve.