A question for pilots on the RJ-series

[nebpor]

Hi guys, small query I always wonder about.

Fly an RJ-100 twice weekly.

1) Why is the RJ the only plane I've ever been on that makes the "woosh!" noise as the flaps go/up down?

It's obviously related to the engine/exhaust flap interaction, but then plenty of planes have big extended flaps but don't do it. Is it because with the high-level wing the engines are in-line with the fuselage, rather than hanging under the fusealge as they generally are in "normal" planes?

2) Transition from takeoff flaps to "clean" wing (if that's the term :E) - the RJ always feels like the handling of the plane markedly changes, i.e. I notice it in the pitch of the plane .... I appreciate that as the Pilot retracts the flaps they might also be changing the flightpath, but it's a kinda "seat of the pants" feeling ... I'm a dodgy flyer at times hence I tend to notice such things.

Does the handling change that much? Again, I'm not sure I ever feel this when in the back of an 320 or a 737/757 ... I just seem to notice it more on an RJ.

3) After a really quick initial climb off the deck, the RJ seems to have a very low rate of climb to cruise - is this because (as I read on here) that it's quite an underpowered plane?

Apologies if all questions daft :}

[ceeb]

Good questions there. I would like to know the answers as well, I do like the RJ's.

Not a commercial pilot, just a PPL but thought maybe the anhedreal wings would make it seem more twitchy with flap changes?. Just an uneducated guess but would like to know the pro's answer.

[Avman]

The question has come up several times before. If you take the time to use the search feature you'll find the answer.

OK here it is. Took me a few minutes.

http://www.pprune.org/forums/showthread.php?t=138702&highlight=146+flap+noise

[WHBM]

There are a range of noises that have surprised the designers over time (RJ flap deployment howl, A320 PTU "dog barking" noise at engine shutdown, A320 with IAE engines "buzzsaw" noise on climbout, etc). With the flap deployment noise on the RJ, BAe developed a modification to address it, but it weighed 100 kg = 2 passengers, so the operators said "the noise is not THAT bad".

I have seen several explanations for it, the most common being that it is the airflow between the flap inner edge and the fuselage side changing as the flaps deploy. Nothing to do with the engines.

On a departure from London City runway 28, right hand circuit, the flaps are taken in at 3,000 feet, just as the aircraft passes overhead Stratford railway station, and the adjacent Olympic stadium under construction. The noise is quite audible from the ground, down on the station platform. I am looking forward to the Olympic commentators mentioning it in 2012. The BA fleet will be gone by then but the CityJet one looks like it will still be with us.

[nebpor]

Thanks Avman - I should have searched :ok:

And cheers WHBM as well. I must admit I love City Airport - never a dull moment!

I especially like how they throttle right back just after retracting the flaps, so it feels like the plane has just stopped in mid air :} Boy am I always so glad when we get to about the M25 and then put the juice back on for the climb to cruise :E

[dhc83driver]

The noise on the 146 / RJ when going from flap 0 - 18, or 18 - 0 i always find a comfort. I was in the sim recently and the simulated noise failed. It felt really strange and without the audible clue was harder to fly (No autopilot or Flap trim compensation). LCY is always good fun, we have to stop at 3000` on the SID and this normally co insides with the flaps coming up. With the auto thrust in it pulls alot of power off to avoid busting the flap limit speed this tends to feel like everything has stopped.

In answer to question 2, yes the attitude of the aircraft changes alot. In cruise clean the RJ has a 5 degree pitch up attitude. with flap 18 its about 0. As the flaps run the Center of pressure on the wing changes and needs to be adjusted for. The autopilot adjusts the trim automatically to make life easier but its not hard in manual mode. you go from a pull to a push as it moves. The flaps on the RJ are massive and give a very large increase in wing area, that's why its so good at small airports.

In answer to question 3. The attitude during climb may not represent the climb rate. At mid weights the RJ climbs as well at a slightly higher speed of 260 - 280kts than a lower speed of 210 ish but the cabin attitude is alot flatter and comfortable but climbing at the same rate. The climb rate or speed is never going to be mind blowing on a 146 as it has enough power, but not a massive amount. but it will go down like a brick thanks to its massive tail airbrake and that is useful sometimes.