Power / speed issues
Printed From: Just Flight Forum
Category: Just Flight Products
Forum Name: HS 748 Propliner
Forum Description: Discussion area for HS 748 Propliner
URL: http://forum.justflight.com/forum_posts.asp?TID=31455
Printed Date: 19 Apr 2024 at 7:12am
Topic: Power / speed issues
Posted By: tdumontelle
Subject: Power / speed issues
Date Posted: 30 Apr 2017 at 6:40pm
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Excited to fly this great looking product. Updated to SP2 and I'm having a few issues: Following the flight tutorial guidelines, I go through engine start. I'm loaded with default passengers and about 80% fuel load. 1. When the engines start the RPMs go to maximum and stay there, also the EGT goes to the red and stays there. After 5 minutes both engines eventually fall back on RPM's and EGT goes down. 2. Take-off seems sluggish. Pulling back on the stick at 110 knots, aircraft but no rotation until 140-150 and then only 500fpm. Gear up and flap clean up improves. 3. Climb out; with RPM's set to 14200 if I try to trim for 150-160knots I end up in a 15 degree pitch up climb. EGT was in the yellow through climb. 4. Cruise. At 15000 feet I can't seem to even get 1400 rpms. Speed is at 240 KIAS or higher at max. AT 220 KIAS fuel flow seems to be at around 800-1000 pph. 5. Approach to landing, the aircraft doesn't want to fly level at 120 with the recommended flap setting. I think I'm missing something with the fuel trim or something else with the start up that may not be in the manual. Any help is greatly appreciated! T Also, I purchased this right before SP2, so never actually flew except SP2 |
Replies:
Posted By: keithb77
Date Posted: 01 May 2017 at 4:43pm
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SP2 was updated many times - do you have the 1.06 download? Cheers Keith
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Posted By: tdumontelle
Date Posted: 02 May 2017 at 11:41pm
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I'm not sure. I downloaded it on 04/30/17 I think. Where can you find the version number? I found a work around for the high rpms at start. I have the fuel cocks shut off and then hit the starter. After it revs up a bit I open the fuel up. Similar to how I start a B1900 or C208. |
Posted By: tdumontelle
Date Posted: 06 May 2017 at 7:28pm
| Ok, did a full reload and made sure it was 1.06. This fixed the startup issue with no sticking high rpms. Rotation is still well after 120knots, climb at 14200 rpms is still at like 16 degrees pitch to maintain 160 - 180 knots. Didn't even try to descend or land. I don't know if there are still problems with the FDE or flight model or if I'm missing some step that's not in the manual. Almost wonder if the airspeed indicator is off or maybe its supposed to be MPH instead of KIA. |
Posted By: tdumontelle
Date Posted: 23 Jul 2017 at 5:53pm
| I did file a ticket on this. They referred it to the developer. Has anyone found some work-arounds for these? I also followed up today to see if there was an update coming out. |
Posted By: Uncle Bucc
Date Posted: 16 Aug 2017 at 1:27pm
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I too have recently had this problem and the aircraft won't take off from the runway. I haven't flown her for quite a while and I have upgraded my flight control systems, rudder pedals etc rather than the "all in one" sticks that are out there. I just fancied a change and after three days feel lost for ideas. I also appear to have trouble getting everything to link to the specific profile type using FSUIPC. Checked their forums nothing there to help with this problem. But I shall persevere. Just fancy doing the Anchorage to Cold Harbour flights that were in an issue of PC Pilot. Happy to read what possible solutions get posted. EDIT: Fixed. FSUIPC has recently been updated plus I was using an earlier version of the a/c. All now seems fine as I just did a small flight from EGCC to EGNT no problem. |
Posted By: thorsten42
Date Posted: 01 Sep 2017 at 9:55am
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Hi all, I just installed the latest 2.01 version into my p3d v4 and I'm getting the same speed problem as described. Afaik I never had it before in FSX or P3D v3 with older installs. As the Fokker is doing nicely with the same engines it has to be something with the 748... any further ideas? Cheers Thorsten |
Posted By: Tobus
Date Posted: 01 Sep 2017 at 10:47am
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I'm experiencing the exact same thing as Thorsten42 describes in FSX:SE, with the news SP201 installer. Fokker behaves like a sportscar and 748 as a tractor with same engines and general characteristics.
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Posted By: almerejo
Date Posted: 01 Sep 2017 at 1:37pm
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Updated to the latest version, and not had any issues both with the power or take off speed issues. However, I do find as it loads in it's 'powered-up, ready to roll' mode, it behaves like a wild bronco ready to break free and gallop away, as I have to keep applying brakes to slow her in the taxi to the take-off runway. So, switched to the C&D Tutorial, and therein I was able to control the taxi speed. However, when calling for full power and take-off speed, there was no issue. After spending a great deal of time in the 737NGX, this aircraft makes a lovely change. Did d long flight TNCA to TNCM with it. Only wish I could get GSX to interact with it a bit better, i.e. catering, fuel. Push-back works fine. |
Posted By: thorsten42
Date Posted: 05 Sep 2017 at 11:47am
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Anybody else experiencing this behaviour? Nice to hear that your install is working almerejo but that doesn't help the other users experiencing the observed behaviour. I just did another start attempt following exactly the documented steps in the tutorial flight but the 748 is def not taking off as expected. Way to slow and even with the trim of +3 not rotating below 120 knots. It feels like flying on one engine and towing an anchor... Cheers Thorsten |
Posted By: almerejo
Date Posted: 05 Sep 2017 at 12:41pm
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Check that both HPC levers are fully forward since you mention that it feels like it is trying to take off on one engine, it may be that one of the engines is not fully receiving fuel via that HPC lever. Also check the gust locks are not engaged. I was basically trying to point out there is nothing fundamentally wrong with this aircraft as she stands in the current version. |
Posted By: thorsten42
Date Posted: 06 Sep 2017 at 6:57am
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In several users opinion there is indeed something fundamentally wrong with this airplane. As stated before I followed exactly the checklists and I know the 748 quite well. I've flown Rick Pipers freeware version for several years and with some given respect it had a lot more system depth to be followed exactly than this recent AH Version including working fuel trim etc... But thats not the point here. We all know what AH planes stand for and they are nice for some relaxed fire and forget flights if you are tired from watching systems in other planes. (even if we know that other releases like the Viscount never reached a state that would be called flyable in all stages ;) ) For the HS I did some further testing and research... What indeed puzzles me a bit is that both the Fokker F27 and the HS748 are meant to provide a somehow compareable behaviour taking into account the engines used and the fact that they were direct competitors. Some sources tell us for the HS748 that for example: [...]This aircraft has a takeoff run of only 2,750 feet, for STOL performance it has a long-span wing, mounted low, with Fowler flaps driven by an electric actuator. The Rolls-Royce Dart turboprops, mounted with their jet pipes above the wings, are rated at about 2,280 hp, though some military versions have 3,200-hp Darts. Most civil versions of the HS 748 seat 40 to 58 passengers and some are equipped for freight or passenger/freight operations.[...] Other sources like https://www.skybrary.aero giving us for both the Fokker and the HS748 regular required runway lengths for takeoff of about 1200m (roughly 4000 feet). The Fokker seems to be a way overpowered then and easily reaches the STOL performance mentioned for the HS. On the other hand the HS doesn't meet the lets say normal figures of 1200m anymore since the last few versions. And for the STOL it would need rocket booster ;) I found a few old installers on my disk and did some tests in my p3d v3 install. Installer marked with SP1 used and the take off performance was what I would expect to match the 1200m runway length. But miles away from the STOL performance. Next try was with installer marked 1.06 and the FDE seems to be way off. Same with the latest 2.01. So honestly I don't think that me or the other users seeing the take off behavior are doing something fundamentally wrong. |
Posted By: almerejo
Date Posted: 06 Sep 2017 at 8:35am
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Ah, Rick Piper's 748. Now, that certainly evokes memories. Pity it never got developed further. Would have been an instant buy for me in P3Dv4. And I bow to your superior knowledge of this particular aircraft. And I was not specifically saying that there was not anything fundamentally wrong to each and every simmer's purchase. What I meant to say was that in my instance, I basically found nothing fundamentally wrong. I was able to take-off from short runways, able to power up to a climb and then cruise for quite a long flight(LEPA-GCLP) and it fulfilled, for me, all the parameters of that Tutorial. I would not go as far as to say it is a totally flawless state-of-the-art FS add-on. Far from it. I just hope that JF look at yours and others issues with it and come up with a SP to resolve it and/or embrace some of Rick Piper's excellent model. |
Posted By: thorsten42
Date Posted: 06 Sep 2017 at 8:39am
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Thx almerejo... yeah lets hope that we'll find whats causing the issue. One question... what runway length is the shortest you get the HS up in the air? Just for comparison. Me not getting it safe into the air below 1300m / 4400feet with v2.01 and 1100m with the older installers. |
Posted By: almerejo
Date Posted: 06 Sep 2017 at 9:11am
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I'll check that out next flight and update accordingly. |
Posted By: almerejo
Date Posted: 06 Sep 2017 at 5:39pm
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Okay, just made a test flight and I can now confirm this aircraft struggles with 100% fuel to climb off a 1420m runway. She just about makes it. I have been using her on normal mainstream airports rather than S/TOL runways, which is why I had no power and climb issues. |
Posted By: tdumontelle
Date Posted: 06 Sep 2017 at 9:44pm
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I sent an email in regards to my original support ticket. I asked them if they were working on a solution or if they just notified the designer of the problem. I haven't had a response yet. I really like the aircraft, and I'm excited to fly it, but its frustrating to have a STOL aircraft that can't STOL. I had the freeware version mentioned above and it was cool so I paid money to get a more refined version. Seems like since it did seem to work in a previous release that a solution wouldn't be too far off. I think I filed the ticket in early May or so. |
Posted By: snave
Date Posted: 07 Sep 2017 at 5:45pm
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Provide take off weight and weather conditions or there is no basis for comparison. Assuming the fuel trim is correctly set (and is actually working in the latest version) you may well struggle to climb off a 1420m runway. STOL means `short` by the standards of jets of the day.
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Posted By: thorsten42
Date Posted: 08 Sep 2017 at 6:30am
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Snave you're absolutely right. I'm using always default fair weather with null wind and standard barometric pressure for test flights with airports near sea level. BUT indeed I was not checking the weight. The fuel trim is not simulated and per manual stays at zero (thats not nice regarding system depth but expected). The only source I found was that the HS was capable of takeoff runs around 2700 feet but not mentioning fuel and load. I've rechecked and yes with default load and reduced fuel (35000lbs actual weight with max gross at 46500lbs) it is indeed capable of taking off around 2700 feet. Nothing more to say than sorry, my fault. I did not follow my own level of professionalism that I expect from others. With the latest tests I would say it acts like the available numbers tell us as far as I can judge. Cheers Thorsten |
Posted By: almerejo
Date Posted: 08 Sep 2017 at 8:21am
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To add to this, I did qualify my last post by stating '100% fuel', the following post from Snave balances out. Nevertheless, a great thread with salient observations. |
Posted By: snave
Date Posted: 08 Sep 2017 at 5:43pm
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`100% fuel` is NOT take off weight. Please understand the terms you use are meaningless unless you also include the context... Here is what is needed to look at take-off performance: 1: Take-off weight - this can be summarised as the combined weight of aircraft, fluids, passengers and baggage. If you give ANY weight or load, give them all or you are wasting everyones time. Especially your own. Its simple enough to read off the figures from the load screen. 2: The weather: Temperature and pressure affect density altitude. These early t/p's had a great power:weight ratio compared to vintage piston props, but when compared to modern turboprop airliners, not so much. Density altitude can cripple performance. Tailwinds and headwinds can boost or limit take-off and climb performance. 3: Runway altitude and direction: For the same reason as above, but also as part of the density altitude calculation. 4: CG - if your Centre of Gravity is outside the correct parameters, the aircraft will struggle to rotate or will fly in an exaggerated posture that increases drag. At max take-off the 748 was NOT a STOL aircraft. Most flight operations were conducted UNDER max take-off weight to get acceptable performance. In fact in the Fifties and Sixties it would have been rare to the point of `not happening` to have an airliner operate regularly at MTO. Look at the climb rate of the 748 at MTO in ISA conditions for a clue - under 500 ft/min. So in addition to calibrating the aircraft for comparison please also recalibrate your expectations. It's a vintage aircraft, brilliant in its day but by the standards of today? Asthmatic, portly and sedate... A good example I've seen in any number of videos is the exaggerated angle on take off. The 748 did not take off like that. It just didn't have the power or the aerodynamics to climb like a homesick angel, UNLESS the weather was kind and the weight reduced. If you are looking at airshow videos please understand the aircraft was specially lightened, with minimal fuel to to do those parlour tricks. Compare the weight, engine power and performance stats with a Dash 8-300 for what 20 years did in aircraft development.
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Posted By: almerejo
Date Posted: 08 Sep 2017 at 6:30pm
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I knew answering to this thread was going to be pointless. I take it all those points you with your expertise have listed here bullet-fashion are all things that are available with this aircraft to standard of one of the high-end that has an FMC where fuel, load, CG, etc,etc to take into account? Tell you, what.............................I am out of here. Guess, I may as well send this aircraft back and ask for a refund. After all, 'the terms I use are meaningless', so I may as well give up flightsimming now and leave the field to the 'experts' !! |
Posted By: almerejo
Date Posted: 08 Sep 2017 at 6:32pm
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To the Moderators, please DELETE this account forthwith! |
Posted By: snave
Date Posted: 10 Sep 2017 at 11:33am
Or use the information imparted to become one. ALL the information asked for can be supplied by simply reading your sims menus and indeed, are within the capability of the simmer to specify. I have no idea why you even mention an FMC? This aircraft didn't have one. If you cannot or will not supply that information we cannot help you.  YOU are the one seeking help, yet apparently getting catty when it's offered, based on what you need to supply to enable advice to be proffered..?  Yes, you may as well give up, as you only gain knowledge through `education`. You, apparently, don't want to be educated. No one here can help you with that. |
almerejo wrote:Posted By: tdumontelle
Date Posted: 11 Sep 2017 at 3:37am
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OK. I'll try to get the thread back on track. I did another test the other day. This time I used 50percent fuel load and default passenger load. I believe the TOW was 31k. I'm not sure if I missed the gust lock in the previous flights, but I for sure did it this time. For take off I rotated right around 120-130 knots with no problem. So maybe the sluggish takeoff was user error (although I didn't see the step written into the learning flight). Other problems were still there. Mainly that engine power settings by the numbers do not result in the expected flight profile. Recommended climb is at 14200 RPMs with an airspeed of 140-150kias. Setting the RPM's to 14200 I end up with a 15 degree or higher pitch to maintain the airspeed. It seems to want to settle in more like 180 on the climb with a 7-9 degree pitch. Cruise also has problems. The aircraft overspeeds well before the recommended 220 KIAS. This was at FL19. Looking at the previous freeware manual it recommended leaving RPMS at 14200 but that results in an overspeed as well. I got so frustrated that I didn't even try to descend and land. |
Posted By: tdumontelle
Date Posted: 01 Feb 2018 at 1:35am
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More tests this week (I really want to use this aircraft). At full load, definitely no rotation at 120-130 (more like 150). Climb out when set to the recommended 14200 rpms and speed of 140-150 or 160 yields an 18 degree pitch. At cruise, the aircraft overspeeds at around 213 or so even though cruise is supposed to be 220 with overspeed I think at 248 or so. At 18000 feet I can't get it to 14200 RPMs but it seems to want to either go 207 or 160. As I raise and lower the the throttle and RPM's it seems to settle into these speeds. Again, all tests on FSX/SP2, null weather this time. |
Posted By: snave
Date Posted: 09 Mar 2018 at 3:56pm
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Take off speed is FAR too high. Normal t.o speed was 105 Kts. Max cruise for the Series 2A was 241 knots. Normal Cruise was 220Kts. Both at 15,000 ft, SL take off distance at GW, ISA was 4,180 ft to 35ft. Landing distance ISA, SL, Max Landing weight was 3,300 ft. Landing speed 94 kts. expect 1,450 ft/min initial climb rate. Climb chart available here: https://doc8643.com/aircraft/A748 Note how fast climb rate falls off with altitude. Sounds like the thing is still overpowered but if you set the sim up for ISA and SL, and then fly it correctly at Gross of 44,495 lb, using the numbers above we can get a suitable yardstick. |
Posted By: tdumontelle
Date Posted: 13 Jul 2018 at 12:31am
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I finally got a chance to run some more tests on the flight model. Tests were done with clear weather, gross weight at 44,496 at TNCM which is basically sea level. Same system as before running FSX on windows 7 64bit, 400 quad processor, no real config tweaks except the highmemfix or whatever that one is. . Take off - tried to rotate at 110 and nothing through like 125, then only slightly with maybe breaking the ground at 140. Climb - as usual the climb was crazy overpower. Manual says 90 percent power, but I don't know how to set that given there is no percent power gauge. At 14200 rpms, to maintain 160 I'm looking at 15 degree pitch up and still edging to 180 plus. At 7 degree pitch up as in the manual, I couldn't really keep it below 190 with very little throttle. Cruise was different this time. No overspeed. I'm not sure if the speed gauge is off or I was reading it wrong, but I was able to get 220 KIAS without overspeeding. I used the shift z red aircraft info to see where the speed actually fell. It looks like 220 is 1 notch above 200 on the outer dial rather than 2 notches behind the 240 on the inner dial. So, no overspeed and fuel burn was about 800 pounds per hour per engine at 15,000 feet running at 11800 rpms. Not sure about the decent profile. I was able to get down following the basic procedures in the manual and land. Full flaps, 110 or so decreasing crossing the threshold. Wasn't pretty but I got her down. No judgement on the sim. All landing a descent could be pilot stuff. Weird that I couldn't steer after I landed. Not sure if it was my yoke or the aircraft. So mainly, still has significant problems under power at take off, and over on the climb. I'm thinking about doing another ticket on this one. The last response to my previous one was that they were sending it to the designers.
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Posted By: Simon73
Date Posted: 13 Jul 2018 at 12:29pm
Feel free to as we're happy to follow up for you. https://support.justflight.com/support/tickets/new ------------- Just Flight / Just Trains Customer Service Staff |