Dangerzone Posted November 17, 2020 Share Posted November 17, 2020 Completely non-PC related but it's got me curious. When I start the UH-1, it seems as though the starter has to get to a certain RPM before I see the rotor blades start spinning - the blades don't immediately start spinning even the tiniest bit until a while after the starter has been held down. Is there a clutch that engages at a certain RPM speed? Or is someone able to advise a clueless noob as to how the starter's speed is not directly proportional to the main blades? I know this isn't strictly a DCS question - but just really curious as to how the turbine, starter and rotor blades work with each other. Link to post Share on other sites
9thHunt Posted November 17, 2020 Share Posted November 17, 2020 I'm not an expert on the huey, but yes, I'm pretty sure there is a gearbox and clutch that has to engage for the rotor to spin. Link to post Share on other sites
some1 Posted November 17, 2020 Share Posted November 17, 2020 In a turboshaft helicopter engine like we have in DCS, clutch is not needed. The power output shaft is not physically connected to the rest of engine. Once the engine spools up to high RPM and starts producing enough exhaust gases, the power turbine will start to move too. https://commons.wikimedia.org/wiki/File:Turboshaft_operation_(multilanguage).svg#/media/File:Turboshaft_operation_(multilanguage).svg There's a clutch too somewhere, but it's there only in case of engine failure. 2 Hardware: Virpil T-50CM, Hotas Warthog, Hotas Cougar, Slaw Rudder, Wheel Stand Pro, GVL224 Trio Throttle, Thrustmaster MFDs, Saitek Trim wheel, Trackir 5, Reverb Link to post Share on other sites
Quadg Posted November 17, 2020 Share Posted November 17, 2020 Using the diagram above from some1. The starter is the backup electrical generator/starter connected to the compressor turbine shaft. Instead of generating electricity as the shaft spins, you use electricity to turn the generator into an electric motor that turns the compressors and starts gas generation (Air flow and compression). Fuel is added and burned. 15% gas pressure is when the power turbine starts to spin (main rotor starts to turn) and you need to hold the starter till 40% for the process to be self sustaining (it will increase to 100% on its own). After the engine is started you set the starter to standby generator and it becomes a backup electrical generator again. The main generator is attached to the transmission gearbox and generates from there. (the power turbine shaft) In the huey the power turbine shaft comes out of the front of the engine and not the back. So the transmission is at the cool end of the engine. But the turbine shaft passes through the compressor shaft and is not directly connected to it. (a shaft within a shaft) Why the engine is to the rear of the rotor. with the exhaust to the rear. The mi-8 has the power turbine shafts coming out the rear and the engines are mounted in front of the rotor. With the exhausts to either side of the rotor and transmission. The free wheeling clutch only operates when the main rotor is turning and the power turbine shaft has stopped. so it only disengages in emergencies and engine shutdown. during start up and normal operation it is always engaged. My Rig: i7 4930k 4.5Ghz, 16GB DDR3 2400, 2x SSD, EVGA 1080 Superclocked, Warthog Throttle and Stick, MFG Crosswinds, Oculus Rift. Link to post Share on other sites
Dangerzone Posted November 17, 2020 Author Share Posted November 17, 2020 Thanks all. I didn't realise that the rotor wasn't directly linked to the turbine - so we basically have two different mechanisms spinning independently of each other, and it's the compressed gas that's generated by one that causes the other to spin. Until there's enough pressure - it won't spin - kinda like a windmill in the wind to use a crude example. Sweet - one less thing for me to be scratching my head over now as I start it. Appreciate the feedback to a real noobish question! :thumbup: Link to post Share on other sites
scoobie Posted November 20, 2020 Share Posted November 20, 2020 Hi, if you're interested, there's this channel on Youtube run by a Canadian guy "AgentJayZ" who owns (works at?) a jet engine repair shop. I like his videos a lot, you can actually see the guts of such engines, in detail, and learn quite a bit about these crazy engines that blow air instead of (properly) pushing pistons :) In some episodes he talks about turboshaft engines with free turbine, i.e. the same design (basically) as in helicopters, for he sometimes gets "ground" engines of such design for repair/overhaul. Good stuff, if you're geeky enough :) 1 i7-8700K GTX1060(6GB) 16GB 27"@1080p TM Hawg HOTAS TPR TIR3 SD-XL button/pot box UH1H Mi8 Ka50 A10CII Bf109 Spit P51 F18 MiG15 F86 supercarrier PG NTTR Normandy Link to post Share on other sites
nsksleeper Posted November 20, 2020 Share Posted November 20, 2020 If I understand you correct your blades doesn't start at all? You have to get sure to turn the throttle to idle. It is the grip on collectiv lever. It needs to turn top to the pilot, hope that helps lg Markus Link to post Share on other sites
Hammer1-1 Posted November 23, 2020 Share Posted November 23, 2020 15% gas pressure is when the power turbine starts to spin (main rotor starts to turn) and you need to hold the starter till 40% for the process to be self sustaining You are supposed to release the starter button at 30% to prevent overheating the starter. Its actually self sustaining at around 25% but technically you are supposed to depress it until at the very latest 30%. Intel 8086k o/c 5.4ghz | 32gb GSkill TridentZ DDR4 3200 ram | Asus Z370 Maximus X Formula| Zotac GTX 1080Ti | eVGA 1000w psu | MFG Crosswinds | Virpil T50CM2/T50 Throttle/warBRD base/TM Hornet | TM Cougar MFD | Dell 34" UHD Curved monitor | TrackIr 5/HP Reverb | Windows 10 Pro Utley | Yeast | 403 http://www.JTF13.com My wallpaper mods and skins Link to post Share on other sites
Tanuki44 Posted November 23, 2020 Share Posted November 23, 2020 The procedure for starting in Huey's manual would it be wrong? Main rotor – Check that the main rotor is turning as Gas Producer speed reaches 15%. If the rotor is not turning, abort the start. Start switch – Release at 40% Gas Producer speed or after 40 seconds, whichever occurs first. Throttle — Slowly increase to set normal RPM. Link to post Share on other sites
Hammer1-1 Posted November 23, 2020 Share Posted November 23, 2020 Well, If Im wrong, Im wrong. Ive been going by the Army manual thats a bit outdated and its been a while since I last looked at it. But I recall the checklist being cut starter at 30% or 30 seconds to prevent overheating the starter. The DCS Huey's engine is self sustaining at += 25% per my experiences. Again, if Im wrong, Im wrong. Intel 8086k o/c 5.4ghz | 32gb GSkill TridentZ DDR4 3200 ram | Asus Z370 Maximus X Formula| Zotac GTX 1080Ti | eVGA 1000w psu | MFG Crosswinds | Virpil T50CM2/T50 Throttle/warBRD base/TM Hornet | TM Cougar MFD | Dell 34" UHD Curved monitor | TrackIr 5/HP Reverb | Windows 10 Pro Utley | Yeast | 403 http://www.JTF13.com My wallpaper mods and skins Link to post Share on other sites
Dangerzone Posted November 23, 2020 Author Share Posted November 23, 2020 Throttle — Slowly increase to set normal RPM.[/i] Oops... I've been doing that bit wrong! I'm like - full throttle once it's self sustaining - give me flight! May have to revisit my startup procedure. :music_whistling: Link to post Share on other sites
Quadg Posted November 24, 2020 Share Posted November 24, 2020 Well, If Im wrong, Im wrong. Ive been going by the Army manual thats a bit outdated and its been a while since I last looked at it. But I recall the checklist being cut starter at 30% or 30 seconds to prevent overheating the starter. The DCS Huey's engine is self sustaining at += 25% per my experiences. Again, if Im wrong, Im wrong. The last time I released the starter too early at 38-9% she started to spin down. And I had to jump back on the starter. The manual says 40% or 40 seconds to prevent overheating. edit: Just tested on the acrobatics server with normal day conditions and she spins down at anything below 40%. My Rig: i7 4930k 4.5Ghz, 16GB DDR3 2400, 2x SSD, EVGA 1080 Superclocked, Warthog Throttle and Stick, MFG Crosswinds, Oculus Rift. Link to post Share on other sites
Hammer1-1 Posted November 24, 2020 Share Posted November 24, 2020 The last time I released the starter too early at 38-9% she started to spin down. And I had to jump back on the starter. The manual says 40% or 40 seconds to prevent overheating. edit: Just tested on the acrobatics server with normal day conditions and she spins down at anything below 40%. I managed to get it to start after it hit 25%. Intel 8086k o/c 5.4ghz | 32gb GSkill TridentZ DDR4 3200 ram | Asus Z370 Maximus X Formula| Zotac GTX 1080Ti | eVGA 1000w psu | MFG Crosswinds | Virpil T50CM2/T50 Throttle/warBRD base/TM Hornet | TM Cougar MFD | Dell 34" UHD Curved monitor | TrackIr 5/HP Reverb | Windows 10 Pro Utley | Yeast | 403 http://www.JTF13.com My wallpaper mods and skins Link to post Share on other sites
Tanuki44 Posted November 24, 2020 Share Posted November 24, 2020 Strange, I also just tested at several values, same results as Quadg, under ~40% of Gas Producer, she spins down. Link to post Share on other sites
Pilot Ike Posted November 24, 2020 Share Posted November 24, 2020 Strange, I also just tested at several values, same results as Quadg, under ~40% of Gas Producer, she spins down. Same here. Link to post Share on other sites
Dangerzone Posted November 24, 2020 Author Share Posted November 24, 2020 Hmm.. I've been able to get it at around 25% - my experience replicates Hammer1-1 Could temperature, QNH, altitude of airport, etc make that much of a difference. (I'm in stable release - not OB incase that's also a factor) Link to post Share on other sites
Quadg Posted November 25, 2020 Share Posted November 25, 2020 Hammer1-1 is hot starting her. If you watch the engine temp below the gas producer then he goes much hotter than I do on a similar start. He is above 625c but I cannot tell if he is above 675. If he is then he is there for too long (10 seconds when max is 5) So he is using more throttle. The real start position is actually below the idle release position, in the page up and page down region of the throttle. But even starting at the idle release position I don't get this hot. And she does not go till 40% And she will get nowhere near 625c So the difference is the amount of throttle used. In external view you may see flames coming out the engine on a hot start. The manual says avoid hot starts. check your throttle is going to zero. My Rig: i7 4930k 4.5Ghz, 16GB DDR3 2400, 2x SSD, EVGA 1080 Superclocked, Warthog Throttle and Stick, MFG Crosswinds, Oculus Rift. Link to post Share on other sites
Tanuki44 Posted November 25, 2020 Share Posted November 25, 2020 So the difference is the amount of throttle used. Exactly, if the throttle is on Idle, check the curve of axis, the mini must be at 0, even at 2% the phenomenon occurs and the temperature goes on red. With the curve starting at 0, the temperature at start-up remains at the minimum of green (~400°) Link to post Share on other sites
Pilot Ike Posted November 25, 2020 Share Posted November 25, 2020 Hammer1-1 is hot starting her. (...) The manual says avoid hot starts. check your throttle is going to zero. Yes, hot starts are pretty bad for the engine, they can really ruin it. I remember from the Bell 206 start-up procedure you are supposed to bring turbine RPM to something around 20% with the starter before even moving the throttle / injecting fuel at all. I was wondering why this isn't the case with the 205/UH-1. Link to post Share on other sites
Dangerzone Posted November 26, 2020 Author Share Posted November 26, 2020 Hmm.. I wonder if that's what I'm doing. I normally use the mouse to 'crack' the throttle so that it's responsive to my hotas knob, and then turn it all the way 'off', then press and hold the starter, and once the engine is self-sustaining I then increase the knob. I wonder if by 'cracking' it to start with is putting too much fuel in the system? Link to post Share on other sites
Jester986 Posted November 26, 2020 Share Posted November 26, 2020 So when I start a real huey I open the throttle all the way, take it down to the idle stop, push the stop release and close the throttle, open it back to full, back to idle stop, push the stop release and turn it just enough towards closed to get it off the cam so I cam close it if I lose power. Fuel on, start fuel on, hold the starter, start fuel off at 25% n1 or 400 egt (thats for a 205 with the -17A) off the starter at 40-45% n1 depending on who you work for. The dcs huey doesn't have start fuel and its a different engine so limitations are a little different. But what you described above should start it fine. Are you waiting to increase throttle until the everything has stabilized at idle? 1 Link to post Share on other sites
Dangerzone Posted November 26, 2020 Author Share Posted November 26, 2020 So when I start a real huey I open the throttle all the way, take it down to the idle stop, push the stop release and close the throttle, open it back to full, back to idle stop, push the stop release and turn it just enough towards closed to get it off the cam so I cam close it if I lose power. Fuel on, start fuel on, hold the starter, start fuel off at 25% n1 or 400 egt (thats for a 205 with the -17A) off the starter at 40-45% n1 depending on who you work for. The dcs huey doesn't have start fuel and its a different engine so limitations are a little different. But what you described above should start it fine. Are you waiting to increase throttle until the everything has stabilized at idle? What I'm doing is opening the throttle until it's back to idle stop (at the stop release point) - I'm guessing that it's too much getting in there then, and I might be hot starting it still. I'll try leaving it completely off and see if it's any different the next time I fly as it's most likely me doing the wrong start-up procedure. Thanks for the tip. :thumbup: Link to post Share on other sites
Jester986 Posted November 26, 2020 Share Posted November 26, 2020 So from my understanding the helicopter was made to be started at the idle stop. They have you start it just on the other side of idle because the idle stop release is electricly actuated, so if you lost electricity you wouldn't be able to shut off fuel and you'd burn up the engine. And I'm pretty sure I've done lazy starts in dcs with the throttle sitting on the idle release so that shouldn't be the problem. Link to post Share on other sites
Dangerzone Posted November 26, 2020 Author Share Posted November 26, 2020 So from my understanding the helicopter was made to be started at the idle stop. They have you start it just on the other side of idle because the idle stop release is electricly actuated, so if you lost electricity you wouldn't be able to shut off fuel and you'd burn up the engine. And I'm pretty sure I've done lazy starts in dcs with the throttle sitting on the idle release so that shouldn't be the problem. Hmm.. will give me something to play around with a little more then. Interesing. Link to post Share on other sites
Frederf Posted November 26, 2020 Share Posted November 26, 2020 So from my understanding the helicopter was made to be started at the idle stop. They have you start it just on the other side of idle because the idle stop release is electricly actuated, so if you lost electricity you wouldn't be able to shut off fuel and you'd burn up the engine. And I'm pretty sure I've done lazy starts in dcs with the throttle sitting on the idle release so that shouldn't be the problem. I always wondered why starts were done with the throttle just on the safe side of the stop. I assumed it was just so it could be quickly shut off on reflex without worrying about the stop button if the start had a problem. I had no idea that the stop button was so mechanically complex that it wasn't just a physical catch that prevented throttle rotation and could prevent a shutdown entirely. Link to post Share on other sites
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