Rain effect disappearing: realistic or not?

[jgoggi 65]

Good morning,

In my opinion it's not realistic to have the rain effect on the windshield completely disappear after around 90-100 knots, so that there is no rain effect in flight. At least the effect should be present up to 140-150 knots. Look at the video below: you can clearly see water streaks on the windshield at 144 knots (around minute 5:30). What do you think?

 

[pete_auau 1,152]

https://www.avsim.com/forums/topic/548153-05jan19-pmdg-747-qotsii-updates-available-via-ops-center/?page=5

 

been mentioned  in here  as well

 

 

 

Edited January 7, 2019 by pete_auau

[jgoggi 65]

Yes, but, as Robert highlighted, that topic is a mix of different issues and requests that create confusion. Better having a dedicated topic in this section...

Edited January 7, 2019 by jgoggi

[rsrandazzo 6,353]

James,

The initial implementation of RainMaker had visible rain present on the windscreen in all phases of flight without regard to speed.  That made me nuts because it isn't what you expect to see in the actual airplane, so I asked Henning and Vin to update it.  We figured it would trip up some simmers who have come to expect big, fat, beetle sized water drops to trickle across the window while flying through rain at 200 knots, but it just isn't that way in the real world in most cases- and this is not based on a collection of youtube videos, it is based upon thousands of hours of flying transport category airplanes, bizjets, classic airliners and warbirds- so i have had a bit of time to make the observation. 

Yes, yes, I know how you love to latch onto specific topics and pound them away- so it is important to note that the characteristics of the window surface, it's maintenance, along with the speed of the airplane, angle of attack, intensity of precipitation, size of the precipitation and temperature of the droplets all play a role here- but by-and-large as you accelerate you are going to see only a slight blurring effect from the motion of water impacting the windscreen and being removed by the boundary layer air.  At what speed that will happen will depend **mostly** on droplet size and temperature.  The larger/colder the droplet the more likely it is to be visible.  These are not discriminators that we can poll for in the sim- so we settled on what we feel (based on MY actual observations in operation) are valid for most experiences- and went with those.

FWIW:  When you get into the high speed range of takeoff, and in MOST phases of flight, your primary indication that it is raining is a background hissing that sounds like an angry snake from a hollywood movie... If i saw water droplets running individually up my window at that speed, I would consign myself to a drug test upon landing.

Simmers are often surprised to learn that windshield wipers are rarely used in jet world, except to clear the view during taxi and during extremely heavy precipitation events at low speed in flight.  They are basically useless contraptions designed to allow us pilots to feel that we are doing something helpful without actually having a useful impact- not unlike bringing a Nerf sword to a joust. 

Heck- some jets don't even have wipers. 

 

 

 

[jgoggi 65]

Thank you, Robert, indeed I was very "cautious" and began with "in my opinion", since I have never experienced (or at least I don't remember) real life cockpit takeoffs/landings with rain. I see that before the effect disappears, you see some water streaks going upwards on the windshield, maybe they should disappear a bit more slowly as speed increases above 100 kts? Again, just my opinion.  

[Sekkha 15]

2 hours ago, rsrandazzo said:

as you accelerate you are going to see only a slight blurring effect

 

would there possibly be a way to  implement this blurring effect up to some higher speeds ?  I think what James refers to is not that there are no droplets visible at higher speeds, but that there is no visual restriction at all in the not wiped areas from relativly low speed upwards,  so even with very heavy rain visibility is  as on a clear sunny day suddenly

best regards

 

[jgoggi 65]

I remember an MD80  full motion sim at my company, the rain effect was obtained only by blurring the scenery outside the windshield... 

[Samany69 41]

4 hours ago, rsrandazzo said:

If i saw water droplets running individually up my window at that speed, I would consign myself to a drug test upon landing.

😂

[LecLightning56 33]

Gentlemen,

May I draw your attention to this video of a Boeing 777 landing at Paris in heavy rain:

https://www.youtube.com/watch?v=y1jFb8y8JmM

If you scroll through to the runway threshold you will note that the intensity of the rain is such that visibility would probably be reduced to unacceptable levels (and hence unsafe landing) unless the wipers were used at full speed. If this phenomenon could be somehow reproduced in the sim, I for one would be a happy man on account of the realism and immersivity of the experience.

Edited January 7, 2019 by LecLightning56

[BrianThePilot 22]

Not relative to the topic but after watching that video, man has PMDG done a great job with their sounds.

[jgoggi 65]

1 hour ago, LecLightning56 said:

Gentlemen,

May I draw your attention to this video of a Boeing 777 landing at Paris in heavy rain:

I think a blurring effect should be added in the area not swept by the wiper and an arc where the wiper blade ends should be visible any way...

[berts 97]

5 hours ago, LecLightning56 said:

If you scroll through to the runway threshold you will note that the intensity of the rain is such that visibility would probably be reduced to unacceptable levels (and hence unsafe landing) unless the wipers were used at full speed. If this phenomenon could be somehow reproduced in the sim, I for one would be a happy man on account of the realism and immersivity of the experience.

Yes, Paul, the QOTSII's Rainmaker effects could always be improved (but I love its effect when it is snowing!).  However, RSR is quite right in what he says, because not even the latest Zero Flight Time B747-8 Simulator will ever be 100% realistic.  If you look very closely at the video in your post you will see that during the final stages of the approach the wipers make very little difference to the clarity of the runway view between wipes and the action of the wiper blade back and forth across the windscreen is in fact fairly intrusive and potentially distracting to the pilot; especially so when it is being operated at full speed. 

During every approach in limiting weather conditions, including heavy rain, the pilots will be focussing virtually all of their attention on what their instruments are telling them, rather than on looking at the outside view.  It is not until the aircraft approaches the missed approach point or decision height (usually somewhere between 50 and 100 ft above the commit point on a manually flown ILS) that the pilot doing the landing really needs to start looking for and including any outside visual cues in his or her scan.  BUT - to keep the aircraft properly aligned on the extended centreline and glide path whilst continuing the descent onto the runway, the flight instruments must still be followed.  More often than not, whenever the pilots have difficulty seeing the approach lights and runway in heavy rain - with or without using the wipers - they will either end up flying a missed approach or have configured the aircraft for a successful autoland using the autopilots!      

The wipers therefore really come into their own when the aircraft is on the ground either taxying, taking off, and especially during its deceleration after landing, because this is when the rain has a much greater effect on blurring the outside view; i.e. at the slower speeds.  You might be interested to know that some Boeing aircraft, such as the B707, were originally fitted with Rain Repellant which could be squirted onto the windscreen and spread with a single sweep of the wipers in flight.  It was apparently meant to act as a smooth film, rather like water running off a Duck's back, but apparently it was highly toxic if it leaked from its container at the back of the Flight Deck and I believe it was hardly ever used in anger; even when landing in heavy Monsoon rains. 

Edited January 7, 2019 by berts

[Sekkha 15]

48 minutes ago, berts said:

  If you look very closely at the video in your post you will see that during the final stages of the approach the wipers make very little difference to the clarity of the runway view between wipes

that´s true..

however the overall visibility through the cockpit windwow is  really not very good in this and many other videos,   and this, I think,  is a bit  the missing point in rainmaker as by now, because from a certain speed on it looks as clear as a on a sunny day

[Guest]

11 hours ago, rsrandazzo said:

Simmers are often surprised to learn that windshield wipers are rarely used in jet world

They're rarely used in auto racing ... we apply a few coats of RainX inside and outside so the water streaks away even at low speeds <100 Mph.  Besides that, above 100 Mph and the wiper motor wasn't sufficient and the blade would just flutter and often I'd just lock it 12 oclock for least wind resistance ... in my other race cars I just removed them completely if the rules allowed.

Having done a recent virtual rain test at KPDX in the 747-8, I used the wipers because "I can" ... they looked good even though I know they are rarely used RW except perhaps during taxi. I have no idea what speed the wiper mechanism is rated to on a 747 but I imagine it has a limit?  

But overall the rain effects combined with OldProp Immersion are VERY convincing even if not 100% accurate.  I'm glad PMDG added the feature.

Cheers, Rob.

[Captain Kevin 586]

6 hours ago, Rob Ainscough said:

I have no idea what speed the wiper mechanism is rated to on a 747 but I imagine it has a limit?  

Funny you mention this. Read about this on another forum, and apparently there isn't one, although there was one pilot who, for whatever reason, decided it was a good idea to try to turn the wiper on at cruise altitude. Needless to say the wiper departed the aircraft very quickly.