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View Full Version : Stall characteristics of a Quicksilver



NJMike
02-24-2014, 05:42 AM
I have a Quicksilver Sport 2S. My flying history, however, has all been in aircraft with the engine out in front. So I have found it interesting that when I reduce power, the nose pitches up instead of down. After thinking about it, it now sounds logical since the engine is aft of the CG.

I have only had my Quicksilver for one full flying season (2013) and decided not to do any stall practice until I fully understand what the stall characteristics are. For instance, with the engine aft of the CG, how does that impact stall recovery? Will the tail have a tendency to drop instead of the nose?

Anyone have any Quicksilver stall experience? Or a similarly configured aircraft?

WLIU
02-24-2014, 07:14 AM
So your source of thrust is above and behind the CG. This means that added thrust pushes the nose down and reduced thrust allows it to rise.

So talking through a power off stall exercise, as you reduce thrust to slow to for the stall entry, you should see the nose rise without needing to change trim You should need less stick force to raise the nose than if you flew a constant power/thrust setting.

Once the engine is a idle power, you should be able to slow into the stall condition, and then lower the nose to return to a normal glide, all with the power at idle. When to increase power, you should expect the added thrust to push the nose down, which means that you will have to add back stick pressure to hold the attitude that you choose to fly as you accelerate in the return to level flight. Which means that adding power slowly will be easier to control than just slamming the throttle to full power.

The above is a long winded way of saying that the effects of your changing the power/thrust setting is a separate issue from the stall behavior of the wing of your flying machine. The best approach to investigating stall behavior is to climb to a higher altitude than you might normally cruise around at and then reduce power to idle and carefully slow the airplane until it starts to feel like it is about to stall. Push the nose down without adding power to gain speed and return to almost level flight, adding power once your airspeed is back in the range that you are familiar with. Climb back up and repeat, flying a little deeper into the pre-stall feel. After a couple of "nibbles" at the beginning of the stall behavior of your machine, if nothing odd or exciting has occurred, fly right into the stall and recover. Do this a couple of times, the do it again while adding some power as part of the recovery.

If I explained what I intended, my point is that you organize the investigation of the unfamiliar flight behavior in small steps that changes one or two variables at a time. You build up your understanding and confidence by doing this until you have run through the full maneuver that you are trying to understand. And for safety, altitude is your friend.

Best of luck,

Wes

1600vw
02-24-2014, 07:19 AM
Yes on an MX or MXL the tail will drop as you reduce the power. On an engine failure it is a lot quicker drop,or the tail drops faster, be ready to push the stick forward faster on a complete engine shut down or failure.

After this they mush out or will not drop a wing they just kinda keep flying with a decent.

Tony

Jim Heffelfinger
02-24-2014, 07:19 PM
I want to redirect what Tony has said - it is true but with a different reference - as noted by Wes. Abrupt thrust changes will cause a dramatic pitch change that should be avoided when near Vs. Power down will pitch up and quickly drop below Vs. Powering up, as if to go around, in an aborted landing will pitch the nose down and might slam the gear. All high wing pushers have this characteristic. So I prefer to use the pitch up or down vs. tail up or down. The plane is not out of W&B just a very high trust line in regards to the drag of all underneath.
That said, a primary flight envelope investigation would be the stall and commonly done during the first few hours of flight testing on a new aircraft or one new to you. Both power on and power off. This is pretty dramatic as noted by Wes in a real power off condition. As noted by many others - wiser than I - YOu fly the plane - pitch down to best glide.
Since the QS is a very draggy air frame - the difference between stall, cruise and Vne is just a handful of MPH and the reason transitional training is needed if coming from a lower drag and higher wing loaded flight experience. It can spank you.
You will find, as noted above, the QS a very forgiving stall. Lots of advance buffet and if properly rigged, a very mushy no surprise stall.

1600vw
02-24-2014, 09:28 PM
As stated above this is not a weight and balance issue. With the airframe within CG the airplane will do this when it is a pusher. Nature of the beast. I am talking power off stalls. You must react faster flying one of these. Some drop the tail or pitch up if that is your favor more then others.

I call it dropping the tail because that is what happens. The result is a pitch up on the nose. This is different then just a pitch up. In going pitch up or pulling the nose up, you are flying the tail, when the tail drops it has stopped flying and it is starting to fall onto itself. Let it fall much farther and you will be in a world of hurt. You will not be able to pick the tail back up to level the plane. Its not about bringing the nose down. Sounds strange but if you think of it this way it will save your butt.

Tony

Buzz
03-10-2014, 08:55 PM
This is pretty dramatic as noted by Wes in a real power off condition. As noted by many others - wiser than I - YOu fly the plane - pitch down to best glide.
Since the QS is a very draggy air frame - the difference between stall, cruise and Vne is just a handful of MPH and the reason transitional training is needed if coming from a lower drag and higher wing loaded flight experience. It can spank you.
You will find, as noted above, the QS a very forgiving stall. Lots of advance buffet and if properly rigged, a very mushy no surprise stall.
The QS does, indeed, have a forgiving stall. No wing drop in the ones I have flown and no nose pitching down.
I don't have any experience in the 2S but have flown most of the other models for several hundred hours.

My recommendation to new QS owners is always to get really familiar with the stall in the QS and the need to get the nose down and get the airplane flying again. In many of the other QS models, if you don't get aggressive on getting it flying again in a complete engine out, you can really get surprised how hard it is without that prop wash on the tail. Especially if you are use to pitching the nose down in a GA airplane and it starting to fly again.

The other safety recommendation I make flying QSs with 2-cycle engines is do some power off landings at some quiet airstrip. Not powered back landings. Full blown, "shut the engine off and fly it all the way to the ground landings". Start out doing hour first one on a straight in final and then work you way until you do it on downwind.

Get familiar with how it handles with no prop wash and condition yourself to respond smoothly when there is no engine running. It's a great confidence builder.

As said, it's a draggy airframe. The bad news is it won't fly far if the engine quits. The good news is you'll get it into some pretty small areas if the engine does quit and you ever need to do an off airport landing if you've got some practice making genuine "power off landings".

My thoughts.