Simviation Forum - How to controll airspeed.

Jun 9^th, 2009 at 7:19am

Flying Mouse Offline
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Been using FsPx for a while now to add realism and log flights.

Logged more then 140 hours in the props (C182, C208B, Otter & C46) I decided to work my way into the mini tubes.

I bought the default Lear45.

Now I must admit, flying props and the C46 taildragger, going into the Lear45, it is heaven.

I applied the basics of flight flying the Lear45 but the aircraft systems are doing so much for me, the very things I had to attend to mannually flying the mentioned props now gets done for my by the flight systems.

The only thing I need to know to make my flying as real as it gets:

Upon decent with the AP activated I would apply speed reductions as applicable and to make sure I am below 250 knots when I move through 10000.

My rate of decent is set at 1500 f/m. Problem is the Lear45's flight system lowers the speed up to a point and the the speed holds as the decent continue. Often at a speed higher then what I set it to be.

I have 2 ways to lower the speed, I can dis-engage the auto throttle and controll it manually OR I can use the speed brake.

I like to avoid the first due to lagged response time when using throttles manually.

Is it advised to use the speed brake in air to bring speed to required levels? What would be a reasonable speed one can start using the speed brakes?

I used speed brakes at 260 knots. Kept controll with them till 1500 feet then dis-engaged.

The landing was spectaculer, 140 knot as per speed charts with a 81 f/m touchdown & a 4 degree pitch.

Only used reverse thurst to 60 knots, full flaps then disengaged with full speed brakes.

I have never flown a prop that had speed brakes so that part of the mechanics is new to me.

Thanking helpers in advance.

Mouse

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Reply #1 - Jun 9^th, 2009 at 10:08am

Brett_Henderson Offline
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Jets are ornery beasts Cheesy

I'll defer to a jet pilot, if/when one appears.. til then, I'd say you have a pretty darn good handle on it already Cool

I don't know the airspeed limits for spoiler/speed-brake deployment, but I know it's pretty high.. Have you ever been descending (pretty high up), in a commercial jet and and then felt like someone was standing on the brakes ?

I don't like using them either (I don't fly jets often anyway). I'll use them well into a descent, just to steepen it a bit.. but what I try to do, is plan my descents (once under 10000msl) to be less steep in the first place. I may "dive" down to 11000 at 2400fps, and then all but level off until the airspeed gets under 250.. and THEN, continue. Hopefully I'm still far enough out for a slow descent.

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Reply #2 - Jun 9^th, 2009 at 10:51am

DaveSims Offline
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What I usually do is idle power descents. That means I will disengage the auto throttle and pull the power to idle, then adjust the rate of descent to hold whatever airspeed I need. In most jets that gets about 2000 f/m. I will also hold my indicated airspeed around cruise (about 300kts), until I have to slow down for the 250 kt speed limit.

Dave

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Reply #3 - Jun 9^th, 2009 at 11:18am

C Offline
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Earth

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I'll add a bit from my perspective, although setting a rate of descent and using autothrottles in anything other than the final approach is alien to me!

Brett_Henderson wrote on Jun 9^th, 2009 at 10:08am:

I don't know the airspeed limits for spoiler/speed-brake deployment, but I know it's pretty high.. Have you ever been descending (pretty high up), in a commercial jet and and then felt like someone was standing on the brakes ?

Due to their nature, they will be usable up to and above Vno/Mno, although in my case they are limited to between 50 and 30kts below Vne, so usable throughout the envelope.

Quote:

I don't like using them either (I don't fly jets often anyway). I'll use them well into a descent, just to steepen it a bit.. but what I try to do, is plan my descents (once under 10000msl) to be less steep in the first place. I may "dive" down to 11000 at 2400fps, and then all but level off until the airspeed gets under 250.. and THEN, continue. Hopefully I'm still far enough out for a slow descent.

I always plan to fly mine at idle as far as possible (fuel efficiency in mind), then if necessary increase power to decrease the RoD if it looks as though we'll be down early nearer the bottom (ATC permitting of course) - I find that much more comfortable than descending later and using spoiler to increase the RoD, and in lieu of taking spoiler below 10000ft when back at 250kt, traffic permitting I prefer to drop the gear and/or flap early with the same effect. All in all makes it a far more comfortable ride for the pax down the back, and from an airmanship point of view keeps the RoD sensible, lessening the chances of creating TCAS nuisance!

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Reply #4 - Jun 9^th, 2009 at 1:06pm

Flying Mouse Offline
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Thank you for the great and much appreciated input everyone!

I will be working on maintaining smooth speed transitions using speed brake when appropriate and of-course within required operating limits.

A real different experience from props Cheesy

Coolermaster Storm Enforcer Chassis/ Corsair TX750W PSU/ Gigabyte Ga-990fxa Mobo/ AMD Phenom X4 965 BE 3.4Ghz C3/Coolermaster V6GT CPU air cooler/ 8GB RAM Corsair DDR3 2000Mhz/ Gigabyte GTX570 Overclocked Edition GPU/ Windows 7 Prem 64bit/ 750Gb & 150Gb (FSX Dedicated) Sata's/ 23" Samsung BX2331 LED / Logitec S510 Wireless keyboard & Mouse. Logitec Force 3D Pro Joystick. Logitec Headset.

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Reply #5 - Jul 16^th, 2009 at 12:04pm

DenisH Offline
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Speed brakes. I may have missed it, but the default Mooney has speed brakes. There's a button on the V cockpit panel t for it. I know this because I have been curious to how a speed brake works.

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Reply #6 - Jul 16^th, 2009 at 12:12pm

Brett_Henderson Offline
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DenisH wrote on Jul 16^th, 2009 at 12:04pm:

Speed brakes. I may have missed it, but the default Mooney has speed brakes. There's a button on the V cockpit panel t for it. I know this because I have been curious to how a speed brake works.

It sure does.. borne of the need to slow that extremely aerodynamic craft down, while not reducing power quicky (turbo-charged engines are particulary vulnerable to shock-cooling).

I've also seen them employed on a special 350hp C182 (sky-diving mod), to get THAT plane down quickly Cool

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