Dash-8

[Guest]

Hi AllI have downloaded the new Dash-8 aircraft and would like to say well done to Jon and all who contributed to it, it is ACE.I like the control panel, the colour makes it look real. And the co pilot well! Does any one have her telephone number? It looks like I am the only one who like her.Thing is..........sorry Jon but I broke it!!! Tried to land at Whidby air park and hit the trees! Its allright though just minus a wing!:+

[Guest jonpoint]

Thanks, Mate!I could send you her number but you have to get past Dan Port first! If you notice, the face of the girl in the cockpit, visible from outside, is someone else. Some of you UK folk may guess it straight away - no, she's not from England ;)The first person to correctly guess who it is can request their own custom Dash-8 livery and callsign. I won't give too much away yet but I have mentioned her name here before. Her middle name is 'Georgine'...She'll kill me for sure now!:-waveJon Point*************************(effyouthree@hotmail.com)*************************

[Christopher Low 5,354]

Jon,That Dash 8 is a joy to fly, but I have been meaning to ask you something. You mentioned that the plane will "nose up" when the power is reduced. This is presumably some kind of real effect, but why does this happen ? Is it something to do with the pitch on the propellor blades ?Chris Low,ENGLAND.

[Hans_Petter 1]

Pardon me answering for someone else again but I can tell you why (actually I thought I did) and here's the issue:The engines are mounted on the high wings. This places them above the center-line of the fuselage. Whenever engines are far above or below the center of gravity you get a pitch response as you change the power. The Lake Renegade has a prop on the roof an exhibits more of this effect. Most GA propeller planes have the prop(s) very close to the center of gravity and so does the Beechjet (well, not exactly props but you know what I mean). Boeing jets have engines below the wings, which causes the opposite pitch response. Whenever the power plant is offset from the center-line there will be some pitch effect as you CHANGE thrust but it will have no effect once all forces are trimmed out and stabilized. Hans Petter

[Christopher Low 5,354]

OK, I realise that. But I would be interested in the PHYSICS of why this happens.Chris Low,ENGLAND.

[Guest Quaxo]

Well, Chris, try to push your keyboard with your finger, putting it in the middle of its lower edge... the keyboard will move nicely. But if you put the finger at a position 3/4 from the left edge, the keyboard will pivot around an axis. This is basically the same phisical principle.Actually, it has to do with inertia (which is "applied" on the CoG) and force (which is applied where the engines are). If the force (thrust) vector isn't parallel with the line connecting the force application point with the CoG point (in other words, if the CoG doesn't fall under the "line of thrust" of the engines), the aircraft will pivot arounf its CoG when you change power settings.When you are trimmed, you don't notice this effect because the elevator trim compensates this "pivoting force". But if you change power setting, the strength of this pivoting force changes, thus the trim can't compensate it anymore.It would be much clearer with a some of drawings. If you need, I can scan some and post them... :-)Cristian

[Hans_Petter 1]

Here's a simple illustration:http://forums.avsim.com/user_files/18486.jpgHans Petter

[Christopher Low 5,354]

OK, so it's the loss of equilibrium that causes the plane to pivot. I guess that I was always thinking along the lines of "reduce power, lose forward momentum, nose drops". However, it should probably more correctly be "reduce power, lose forward momentum, plane SINKS". Am I correct ?Chris Low,ENGLAND.

[Guest Quaxo]

Well, with an "high-engines" aircraft, it's more or less "reduce power, loose forward momentum but nose rises, so AOA increases, plane goes UP loosing even more speed, so after a short while it drops (and nose goes down, too)". It can get a little annoying to fly a plane like that - that's why you should "anticipate" such attitude changes when changing power settings. :-)Cristian

[Guest jonpoint]

Chris, without detracting from Hans Petter's great explanation, the issue here is that an increase in power can only result in the aircraft climbing AS IT ATTAINS A GREATER AIRSPEED. As it takes some time to gain airspeed, the 'offset' effects occur initially. It is always the velocity of an aircraft that determines the ability to exert control via the control surfaces. Engine power simply allows us to roughly control the speed of the aircraft and, given how light air is, one must push a lot of air to accelerate a 12 or 18 tonne aircraft ;)If you are already descending, applying power WILL increase your velocity so, if you were descending at 1500ft/min and doubled your speed, you would now be descending at 3000ft/min (at twice the impact velocity too!!!). This obviously will not recover you from descending too fast :-eek Pull the nose up, extend the flaps and 'ride' the stall speed instead. It's amazing how reluctant people are to just yanking back on the stick and using inertia to gain height whilst the engines spool back up. This is why we descend well above stall speed.OK, we got that sorted out...So, no takers for the livery prize then? I might have to answer it myself and do my own then... hang on, that defeats the purpose!'My' girl gets to live another day in anonymity ;)PS The Horizon livery is almost 100%. I'll post some shots soon :-):-waveJon Point*************************(effyouthree@hotmail.com)*************************

[Guest R_Driscoll]

Hmm, Elizabeth Georgina Windsor?Mrs X. Georgina Blair?One of the spice girls?Boy Georgina?The Duchess of York?(oh dear, I'm bit out of date here I think - I don't know too many recent (post 1950) pop groups). Its not Lizzy Georgina Taylor of course?OH, got it, that lady who plays M in Golden Eye. No.Is it A or B from ABBA?

[Christopher Low 5,354]

I'm going to forget that this thread ever existed, and just concentrate on FLED for a while....... :-)Chris Low,ENGLAND.

[Hans_Petter 1]

I would guess at Jon's daughter or wife (basic psychology :-)) According to Jon she's not British (thus, Aussies make sense) but then, why would UK folks be in a special position to recognize here? Hans Petter

[Hans_Petter 1]

Jon wrote:If you are already descending, applying power WILL increase your velocity so, if you were descending at 1500ft/min and doubled your speed, you would now be descending at 3000ft/min (at twice the impact velocity too!!!). This obviously will not recover you from descending too fast Pull the nose up, extend the flaps and 'ride' the stall speed instead. It's amazing how reluctant people are to just yanking back on the stick and using inertia to gain height whilst the engines spool back up. This is why we descend well above stall speed.----------Well, there's one important aspect missing here -- if you apply power and pick up speed you will generate more lift. The initial increase in sink rate during this "power dive" will be superceded by nosing up and climbing. If you really want to dive bomb the airport you'll have to apply increasingly more forward stick pressure as the plane picks up speed. Provided you're well above stall speed you may pull up a bit as you apply power, anticipating that initial downward push. However, if you are flying high above the ground and apply power without making any corrections the sequence will be like this:1) Plane noses down and picks up speed once the engines spool up (Keep in mind that the jet engine spool delay and the inertia of the plane preclude an instant response). 2) More speed generates more lift3) The nose swings back up and the extra power goes into climbing (or, reduced sink rate) rather than effecting a faster descent.Evidently, we haven't got time to run through a sequence of attitude changes while we're about to land and the pitching must be anticipated, caught and limited. With high-mounted engines, be prepared for a quick nudge of forward stick as you cut the power and a quick nudge of back-pressure as you apply power. Just a nudge to counteract the transient pitch effect of the high-mounted engines :-)Hans Petter

[Guest Quaxo]

>Is it A or B from ABBA?Actually, I believe that both Abba girls were A... (Agnetha and Anni-Frida?). And the Dash8's copilot really doesn't look like a male to me! :-)By the way, I really like the copilot in the Dash. I understand that she limits the outside view; but in real life, you wouldn't fly such an aircraft without a co-pilot, and he/she would limit the view in the same way... Or not? But it is true that she would be a greater distraction in real life than a male co-pilot... ;-)Cristian