John2 196 Posted January 27, 2022 Share Posted January 27, 2022 In the MSFS Dev Q&A yesterday, they mentioned that they are working on new propeller aerodynamics in preparation for helicopters. They indicated that these would also benefit fixed wing aircraft and that they would be introduced into the King Air turboprop. Can we assume that these new features will also be incorporated into the Twin Otter? John. Link to comment Share on other sites More sharing options...
Jan R. Storelvmo 67 Posted January 27, 2022 Share Posted January 27, 2022 There's already another thread about this topic. I'm really excited about this too. Seems to fix all the problems we currently have with turboprops according to Seb at Asobo. Amazing presentation yesterday. Link to comment Share on other sites More sharing options...
John2 196 Posted January 27, 2022 Author Share Posted January 27, 2022 2 hours ago, Jan R. Storelvmo said: There's already another thread about this topic. I'm really excited about this too. Seems to fix all the problems we currently have with turboprops according to Seb at Asobo. Amazing presentation yesterday. Yes and he seemed to indicate that incorporating the new prop aerodynamics would be relatively easy for developers to do. Hopefully that will turn out to be the case. Link to comment Share on other sites More sharing options...
Jan R. Storelvmo 67 Posted January 28, 2022 Share Posted January 28, 2022 1 hour ago, John2 said: Yes and he seemed to indicate that incorporating the new prop aerodynamics would be relatively easy for developers to do. Hopefully that will turn out to be the case. Yes, I hope so too. Looks really promising. Link to comment Share on other sites More sharing options...
StanTGM 38 Posted February 11, 2022 Share Posted February 11, 2022 I have not been able to figure out how to feather the props. The manual gives some hints as to thrust and prop lever positions required for feathering position, but I can‘t make it work. The props are feathered in the cold and dark cockpit and move into the „normal“ position during start-up, but as I said: I‘m not able to bring them back to feather. Am I missing something? Link to comment Share on other sites More sharing options...
FlightBurky 7 Posted February 12, 2022 Share Posted February 12, 2022 There is a function called "toggle propeller reverse thrust". If you activate it you can move the propeller further down into the beta range. Link to comment Share on other sites More sharing options...
josecolme 9 Posted February 20, 2022 Share Posted February 20, 2022 On 1/27/2022 at 4:04 PM, Jan R. Storelvmo said: There's already another thread about this topic. I'm really excited about this too. Seems to fix all the problems we currently have with turboprops according to Seb at Asobo. Amazing presentation yesterday. Can you share the link please? I can't find it. It would be interesting to see if Aerosoft will implement this on the Twin Otter. Link to comment Share on other sites More sharing options...
Jan R. Storelvmo 67 Posted February 20, 2022 Share Posted February 20, 2022 38 minutes ago, josecolme said: Can you share the link please? I can't find it. It would be interesting to see if Aerosoft will implement this on the Twin Otter. It's been a while now, but this thread should be here somewhere. MK confirmed that Aerosoft will implement it as soon as it's stable. Currently there is no documentation for the new prop technology. Improvements to the aerodynamics is coming in SU9 which will further improve the aerodynamics and fix issues with accelerated slipstreams from the prop etc. Exciting times ahead! However, there are still issues with the turboprop simulation in general. ITT is still way off and we still lack a way to assign beta and reverse to an axis (like in X-plane) in order to make power management easier on the ground. And, as we've also seen, you can still start a turbine with fuel on without any consequences... I sincerely hope improvements to engine simulation is next. Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted February 21, 2022 Aerosoft Share Posted February 21, 2022 There are still a few rather confusing elements about the new prop model, but Alexander is for sure looking at it in great detail. One of the first issues we run into is that we need a whopping lot of data (props surface, profile, shape and twist angle of the propeller. Now of course we know it is a Hartzell Model HC-B3TN-3 Blade Model TI0173 + 1, but after some searching we are not able to find the information we need. I called Hartzell just now and they are not very forthcoming with this information. Anybody here got a lead I can follow? We also have to understand how the default C208 and the KA350 can use the same model for this. Of course the two aircraft could hardly be more different (speed, power, prop) so there most be some configuration somewhere else. So all in all very promising, we just need to learn how to use it! Link to comment Share on other sites More sharing options...
taw1962 21 Posted February 21, 2022 Share Posted February 21, 2022 This data sheet gives some prop information: https://paracleteaviation.com/wp-content/uploads/2017/10/Twin-Otter-Type-Data-Sheet.pdf Propeller: Hartzell Hub: HC-B3TN-3, -3B, -3BY Blades: T10173+1, T10173E+1 Diameter: 8 ft. 6 in. nominal (8 ft. 4 in. minimum after repairs) Pitch Settings at 30" Station: Feather +87° Take-off Low Pitch +17° Idle Blade Angle +12° Reverse Blade Angle - 9° Propeller limits: Propeller (Np) - Take-off 2200 r.p.m. (100%) Max. Continuous 2200 r.p.m. (100%) Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted February 21, 2022 Aerosoft Share Posted February 21, 2022 Yes, that we have.... it's really the profile that is most determining. Link to comment Share on other sites More sharing options...
taw1962 21 Posted February 21, 2022 Share Posted February 21, 2022 Maybe a photo would help? I wouldn't be surprised if the written profile dimensions were a 'trade secret': Please login to display this image. Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted February 21, 2022 Aerosoft Share Posted February 21, 2022 Lol, at the local flying club they actually have one of those blades, but even then you would never be able to find the profile. I also have no idea how the surface is actually counted. Down to the hub? Down to the point there the profile is 100% symmetrical? Link to comment Share on other sites More sharing options...
taw1962 21 Posted February 22, 2022 Share Posted February 22, 2022 If you could borrow the flying club's blade, you could have it laser scanned at a specialist engineering facility but that may be more expense than it's worth! I found a small clue in an article about blended airfoil blades on Hartzell's website: https://hartzellprop.com/hartzell-introduces-new-blended-airfoil-technology/ Here's the relevant bit: Quote The “blended” propeller designs allow for the incorporation of different airfoils along progressive sections of a blade. Thus, the design of the blade mid-section may be maximized for developing low-speed thrust while the tip sections may be optimized to reduce noise levels. In the past, most propeller designs for aircraft equipped with piston engines made use of one basic airfoil series across the entire length of the blade which can compromise aircraft performance or produce high noise levels. Maybe the Twin Otter had the earlier one airfoil section blades? Link to comment Share on other sites More sharing options...
Moach 97 Posted February 26, 2022 Share Posted February 26, 2022 Propellers have a "Characteristic Radius" (commonly around 75% towards the tip) at which the varying dimensions of the propeller are more or less averaged out. This point along the blade is typically taken as the reference when figuring a propeller's mean specs. Most simulators use this method to approximate propeller performances, it generally works well enough that only a very specialized expert would be able to tell the difference. For anything more advanced, you'd end up going with full CFDs, which isn't exactly a real-time solution for general simulation use. Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted February 28, 2022 Aerosoft Share Posted February 28, 2022 We are at this moment testing the tweaks done on the release version of SU8. But the advantages are not massive. Link to comment Share on other sites More sharing options...
zedkay 0 Posted March 4, 2022 Share Posted March 4, 2022 Hi all. Just downloaded the SU8 patch for the Twotter and am having trouble feathering the propeller. I was hoping that the autofeather functionality would be modelled, along with the ability to feather the propeller. Unfortunately autofeather does not arm above 86-88% NG as the manual indicates it should, despite being selected: Please login to display this image. I got airborne and pulled back condition lever 1, shutting off fuel from engine 1. It began winding down, so I took prop lever 1 back to feather. A note on the panel says to not retard the power lever back on the failed engine past half way until the prop is feathered, so I left both power levers full forward hoping this would actually allow the feathering of engine 1’s blades. The RPM began slowing and the animation of the propeller in feathered position showed, although windmill slowly in the breeze whilst climbing at 80 knots IAS. Please login to display this image. Please login to display this image. At this point I brought the power level on engine 1 back to idle, but there was no change to the props. After a few seconds the power level automatically jumped backed to full forward position, despite not touching the controls. This happened repeatedly every time I tried it. The rotation of the propeller did not stop however, and as I leveled the aircraft, the prop then sped up to 10% RPM and stayed there, with the propeller animation returning to a spinning disc again. I’m not sure if this is accurate to the real aircraft- some of the lighter GA aircraft I’ve flown in real life will have a full stationary prop once feathered and in level flight, but a gentle windmilling prop is not unheard of either. Please login to display this image. I pulled the fire handle to completely shut off fuel to the engine as well- but again no change. I also note that the annunciator for the Gen 2 fail had also lit up, despite engine 2 running normally. I carried the aircraft back into land for a single engine touchdown, and upon coming to a stop on the ground, the propeller animation returned to the feathered position and stopped still. So quite a disappointing experience, but I’d be interested to hear if I am using an incorrect technique perhaps? TIA. Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted March 4, 2022 Aerosoft Share Posted March 4, 2022 I'll as the developer to comment. As far as I am aware all the possible options are now used. Link to comment Share on other sites More sharing options...
John2 196 Posted March 4, 2022 Author Share Posted March 4, 2022 Where is the patch for the props? John Link to comment Share on other sites More sharing options...
Developer metzgergva 210 Posted March 4, 2022 Developer Share Posted March 4, 2022 I have done a check-flight. The feathering worked as the prop RPM dropped to 0. The visual impression hat a feathered prop but slowly turning with 20 RPM even in the opposite direction. So the feather angle needs to be adjusted in the next revision. I also saw that, for no obvious reason, the Prop lever changed back to the low RPM position and by that the prop started to rotate again at 75%. Again pulling back the lever into Feather made it slow down again as before. I would need to search why that state of feathered is returning without specific input. Stay tuned! Link to comment Share on other sites More sharing options...
Developer metzgergva 210 Posted March 4, 2022 Developer Share Posted March 4, 2022 Okay I found at least on my Installation a solution which may help others too. When I pull back my hardware RPM lever, the RPM drops to slightly above 1800 RPM. I can see, when I pull back the RPM Lever in the cockpit that there is 1-2 mm dead travel left before the sound hitting the door plays. So my levers are not 100% on zero value! Solution: Add in the HW controller under SENSITIVITY some EXTREMITY DEAD ZONE. -5% worked for me that, when in FEATHER, the HW does not interfere with a small input from its LOW RPM position making the RPM lever jumping to LOW RPM. Link to comment Share on other sites More sharing options...
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