Speed bugs on takeoff not quite correct

[Guest neil_c]

Dear PMDG,Since realism is the goal, please allow me to point out some inaccuracies with the behaviour of these speed bugs during takeoff and initial climb.MAGENTA SPEED BUG AND MCP WINDOWI noticed this on the day of release but did not want to post details until other major issues were resolved.For takeoff, V2 is set in the speed window. Upon pressing TOGA, the speed window incorrectly has 20kts added to it while the speed bug is incorrectly forced up by 20kts. The speed bug and the speed window should both remain at what was initially set, ie. V2. Once a positive climb is established, the flight director should then pitch for V2+20kts, even though the speed bug and window remain at V2.The 20kts should be added to the speed bug and window when one of the following events occur after takeoff:(i) The MCP speed selector is rotated or(ii) A new pitch mode is engagedWHITE V2+15 SPEED BUGThis bug should appear during the takeoff roll but it is not appearing until airborne. It should then only be removed upon first flap retraction or when Vref is selected from the FMC, but it is being incorrectly removed upon reaching the acceleration altitude.I don't have access to an AOM so please check that my memory is correct on these items. I hope these will be added to the list of fixes; the effort has been made to implement the speed bugs and TOGA mode, so it seems a shame for them to be not quite correct.

[crvm 0]

You always set V2 in the IAS/MACH window. In TO mode if you engage an autotpilot, the pitch mode automaticlly engages in LVL CHG and the picth field of the FMA shows MCP SPD and the A/T feild shows N1. The MCP IAS/MACH window and airspeed cursor change to V2 + 20 and the roll mode engages HDG SEL unless a different mode was selected after takeoff. SO in this particular case it will change the bug and window but I agree that I don't see it happening on engaging TOGA...[h4]Best Wishes,Randy J. Smithhttp://img.villagephotos.com/p/2003-8/196432/winglets_lg.jpg [h3] AMD XP 2200 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF2 MX 32 MEG and still runs GOOD!|WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"[/h3]

[rsrandazzo 6,353]

Hey Niel-I tried like heck to get in touch with you before initial testing started 5 months ago.... All the email I sent you bounced..Drop me an email with your current contact information, will you?

[Guest Ian_Riddell]

Sounds pretty good to me, Neil... I think most of these were mentioned in an earlier message thread, shortly after the sim's release. An NG pilot told me about the bug jumping to V2+20 when the MCP speed selector was rotated.I thought it was being looked into already, tho'?Cheers.Ian.

[Guest neil_c]

My mistake, the MCP speed window is working correctly. It does indeed remain at V2 after pressing TOGA and has 20kts added upon engaging a new pitch mode. I seem to remember it not doing this before; it must have changed in one of the patches.However, the other inaccuracies remain, they are:1. MCP speed bug should remain at V2 after pressing TOGA, and should switch to +20kts only when a new pitch mode is engaged or when turning the MCP speed selector. While the bug is at V2, the flight director should still pitch for MCP speed +20, ie. V2+20.2. MCP speed window should switch to +20kts when turning the MCP speed selector (it does switch when engaging a new pitch mode).3. White V2+15 bug should be visible during the takeoff roll and only disappear upon first flap retraction or selection of Vref from the FMC, not when climb thrust automatically engages at the acceleration altitude.Of course, an engine failure alters the speed bug and flight director behaviour during takeoff; perhaps something to look at if implementing optional failures in the future.

[Guest neil_c]

Is anyone at PMDG looking into this for the next patch?

[crvm 0]

Hey Neil, I don't get # 2 on your last post? When you manually increase speeds on the MCP to retract the flaps, the FD no longer commands V2 + 20 and PITCH will be to maintain MCP speed. So in this case you saying that changing the MCP speed will switch the window speed display to V2 + 20 does not seem to add up?[h4]Best Wishes,Randy J. Smithhttp://img.villagephotos.com/p/2003-8/196432/winglets_lg.jpg [h3] AMD XP 2200 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF2 MX 32 MEG and still runs GOOD!|WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"[/h3]

[Guest Ian_Riddell]

Randy, this is the response i received from a pilot after I asked about the MCP speed after takeoff.On the 737, pilot procedure is to set V2 in the MCP IAS window. When the flight director takeoff mode is engaged, the FCC FD commands are for the MCP window plus 20 knots, which is V2 + 20 as long as you set the MCP correctly. (My note: He says FD commands, not MASI bug). The speed set in the MCP window does not change without some crew action.The numbers displayed in the window remain at what you set until the FD takeoff mode is exited, or the MCP IAS knob is moved. If you move the knob even 1 click, the number display will have 20 knots added to it and thus then be in synch with what the FD bars are commanding. If you select LVL CHG or V/S, 20 knots is instantly added to what is displayed in the window, which also then makes the command and the window agree. If VNAV is engaged, the window blanks of course. However, note that on the 737, VNAV engagement before flap retraction is highly discouraged since the FCC does not have any knowledge of the position of leading edge devices. (placard limiting only looks at the trailing edge flaps) Thus if a leading edge device fails to retract, there is nothing in any of the systems to prevent overspeeding the leading edge device. Once flaps are up and the crew has verified that the LE extended and transitlights are extinguished, then it is OK to engage VNAV."Hope this makes sense?Cheers.Ian.

[Guest neil_c]

Hi Randy,>When you manually>increase speeds on the MCP to retract the flaps, the FD no>longer commands V2 + 20 and PITCH will be to maintain MCP>speed. True, but I think you're talking about when pitch mode is no longer in TO/GA above the acceleration altitude. When exiting TO/GA mode, the MCP window correctly jumps 20kts. The problem exists when pitch mode is still in TO/GA and the MCP speed window is showing V2. If you turn the speed selector at that time, the speed in the window should jump +20kts.If you think about it, this is simply setting the speed window to the current aircraft speed (assuming the FD is followed). To see this in action, check out the "other 737" :DLet me know if you still need clarifcation. Do you agree on my other points (which I feel are more important)?

[Guest neil_c]

All sounds good to me Ian, and this backs up my points #1 and #2.Let's get it in the patch! :DPS. Don't forget the disappearing white V2+15 bug though!

[crvm 0]

Well not quite the point I was making but here, In this case, in TO mode and reaching 400 AGL you engage a ROLL mode i.e. HDG SEL, LVAV (you will be in TOGA still). At flap retraction altitude, push N1 to select climb thrust and you manually set the flap retraction speed on the MCP. It does not jump to the UP speed or V2 + 20, you must set it in this case. This is correct, in fact right off the Boeing CBT for the 700. We already confirmed what the proper window display is for engagement of a pitch mode in TO. http://forums.avsim.net/user_files/34468.jpg[h4]Best Wishes,Randy J. Smithhttp://img.villagephotos.com/p/2003-8/196432/winglets_lg.jpg [h3] AMD XP 2200 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF2 MX 32 MEG and still runs GOOD!|WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"[/h3]

[crvm 0]

1] I think you are right here 3] You could be correct, will have to double check this also. But we should be carefull when comparing the classic (and MORE SO when comparing that *Other sim*) with the NG in some cases and need to use the ( NG AOM or CBT etc) to be 100% sure ;)[h4]Best Wishes,Randy J. Smithhttp://img.villagephotos.com/p/2003-8/196432/winglets_lg.jpg [h3] AMD XP 2200 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF2 MX 32 MEG and still runs GOOD!|WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"[/h3]

[Guest neil_c]

Hi Randy,Yes, I'm all too aware of comparing the NG to Classics but the speed bug behaviour for our purposes is common to both. Your post earlier about manually pressing HDG SEL at 400ft and then N1 to get climb thrust is all Classic stuff I noticed ;)I'd just put together a good post explaining my point 2 again when now my PMDG software is performing correctly in this area... which makes me look like an idiot! As soon as I touch the MCP speed selector in TO/GA mode, the speed window jumps by 20kts and all is good again. For example, if my V2 is 130kts then one click up of the speed selector would change the window from 130kts to 151kts.So that just leaves points 1 and 3.What's your role exactly Randy? Are you in regular contact with the developers to pass on confirmed bugs?

[crvm 0]

Hello again Neil, I am a beta tester for this aircraft and have been since day one so yes to your question ;). Some have made negative comments about the this beta process but I am proud to be a part of such a dedicated team of flight sim enthusiasts with a desire to provide the community with the most advanced 737NG ever produced for Flight Simulator. I would also like to say that PMDG are very interested in getting this aircraft correctly modelled and even though they might directly respond to every post, they do take note. A lot of items that get mentioned are known and are on the list of items to correct or model. These type of threads are the best for everyone and most important, they are fun. I really enjoy trying to figure out how something is suppose to work. Ian always keeps me on my toes and enjoy reading his posts. I hope we see many more of these types of threads in the future..[h4]Best Wishes,Randy J. Smithhttp://img.villagephotos.com/p/2003-8/196432/winglets_lg.jpg [h3] AMD XP 2200 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF2 MX 32 MEG and still runs GOOD!|WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"[/h3]

[Guest BrunoF]

Hi Randy!I have the same CBT. It's very detailed and helpfull, but, in the other hand, a little "basic" to get into details (Depends on which ones, of course) -- Dont know if this MCP applies to the kind of comment like the one below:For example,In the CBT it says that the aircraft colds the air to the Coldest Pack Temp and then uses Trim Air to warm the other 2 zones, which is correct for the 737-4/8/900 Series, but not for the 737-6/700 where uses the pack output temperatures are independently controlled.Best,Bruno Francescoli.