Two questions, for the taildraggers I think.
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1. Loss of directional control on the ground (usually on landing) variously caused by landing with drift, overcorrecting small swings, not paying attention. CofG behind the mainwheels means that tailwheel aircraft have less natural directional stability on the ground than trikes.
2. Landing on the main wheels only, with the tail wheel held above the ground. This allows more directional control on landing due to slightly higher speed and less rudder masking than the alternative (3-point) landing. The CG behind the main wheels means that there is a tendency for the tail to come down on landing thereby increasing the AoA and sending you airborne again. The technique is usually to keep a small amount of power on, touch down very gently and apply forward pressure to keep the tail up after landing.
2. Landing on the main wheels only, with the tail wheel held above the ground. This allows more directional control on landing due to slightly higher speed and less rudder masking than the alternative (3-point) landing. The CG behind the main wheels means that there is a tendency for the tail to come down on landing thereby increasing the AoA and sending you airborne again. The technique is usually to keep a small amount of power on, touch down very gently and apply forward pressure to keep the tail up after landing.
High Flying Bird
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A groundloop is a loss of directional control on the ground, caused by a large audience.
A wheely good landing is superb directional control just above the ground, caused by a lack of audience.
A wheely good landing is superb directional control just above the ground, caused by a lack of audience.
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Originally Posted by AerBabe
A groundloop is a loss of directional control on the ground, caused by a large audience.
A wheely good landing is superb directional control just above the ground, caused by a lack of audience.
A wheely good landing is superb directional control just above the ground, caused by a lack of audience.
ain't that the truth
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Groundloops
Another question For Mart 1 ( is that GJG By chance )
Used to be the owner a Pitts S1c Ex homebuilt, which I wrote off at Norwich with the most spectacular of groundloops. It was fitted with the Old (Auster ) type Non Titanium Bungee cord system U/C.
The EAA Tech Tips was full of Pitts departure incidents, which were put down to the Toe in / Toe out of the main wheels changing as the A/C moved forward and that the A/C was Close Coupled.
I have read many definitions of 'Close Coupled' and none make sense.
1 What does it mean?
2 Why does it effect a Pitts more so than other Aero's types of the same basic design.
Cheers
Orions***
Used to be the owner a Pitts S1c Ex homebuilt, which I wrote off at Norwich with the most spectacular of groundloops. It was fitted with the Old (Auster ) type Non Titanium Bungee cord system U/C.
The EAA Tech Tips was full of Pitts departure incidents, which were put down to the Toe in / Toe out of the main wheels changing as the A/C moved forward and that the A/C was Close Coupled.
I have read many definitions of 'Close Coupled' and none make sense.
1 What does it mean?
2 Why does it effect a Pitts more so than other Aero's types of the same basic design.
Cheers
Orions***
Last edited by orionsbelt; 17th Apr 2006 at 19:12.
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Close coupled = short-arsed.
The S1 Pitts is only 15'5" so it is inclined to be twitchy - a longer fuselage provides greater directional stability, through greater inertia.
The undercarriage track is also narrow, so the aircraft is less stable, particularly when the pilot's inability to handle reduced directional stability leads the aircraft away from the runway centreline and the yaw leads to a roll and hence to a groundloop.
The Pitts S2B & S-2C are both a fair bit longer (about 4') so more stable, but still need care on the roll out.
The S1 Pitts is only 15'5" so it is inclined to be twitchy - a longer fuselage provides greater directional stability, through greater inertia.
The undercarriage track is also narrow, so the aircraft is less stable, particularly when the pilot's inability to handle reduced directional stability leads the aircraft away from the runway centreline and the yaw leads to a roll and hence to a groundloop.
The Pitts S2B & S-2C are both a fair bit longer (about 4') so more stable, but still need care on the roll out.
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No, not GJG, MWA in fact (PM if you want to know more).
I think you've raised a couple of different points here:
When people talk about close coupled for the Pitts, it really means that the short fuselage means that the tailwheel is relatively close to the CG. It also has a relatively low inertia (Izz in engineering terms), so is relatively easy to accelerate round the vertical axis (and all other axes for that matter), and the relatively short distance between the wing and the tailplane/rudder makes it less directionally stable in an aerodynamic sense - great for aerobatics, less great for relaxed ground handling.
As for toe-in/out; a small amount of toe-in will cause the drag to be reduced slightly on the inside wheel if a swing starts, and the yaw moment that this creates is stabilising i.e. it wants to swing you back straight again. For toe-out the converse is true, and any deviation from straight ahead is exaggerated. The elasticity of spring-bar type undercarriages means that drag on the wheel wants to turn the wheels outwards towards a toe-out configuration and also a tendency to shimmy. So, although good for weight, cost and simplicity; less great for ground handling.
Just off too play with the Chippy now for some relatively stress-free fun.
Oh and I agree, directional stability is also inversely proportional to the number of people watching.
M1
I think you've raised a couple of different points here:
When people talk about close coupled for the Pitts, it really means that the short fuselage means that the tailwheel is relatively close to the CG. It also has a relatively low inertia (Izz in engineering terms), so is relatively easy to accelerate round the vertical axis (and all other axes for that matter), and the relatively short distance between the wing and the tailplane/rudder makes it less directionally stable in an aerodynamic sense - great for aerobatics, less great for relaxed ground handling.
As for toe-in/out; a small amount of toe-in will cause the drag to be reduced slightly on the inside wheel if a swing starts, and the yaw moment that this creates is stabilising i.e. it wants to swing you back straight again. For toe-out the converse is true, and any deviation from straight ahead is exaggerated. The elasticity of spring-bar type undercarriages means that drag on the wheel wants to turn the wheels outwards towards a toe-out configuration and also a tendency to shimmy. So, although good for weight, cost and simplicity; less great for ground handling.
Just off too play with the Chippy now for some relatively stress-free fun.
Oh and I agree, directional stability is also inversely proportional to the number of people watching.
M1
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agree with all been said, I'm flying a s2b at the moment and I find the approach and flare much easier if you carry a few extra knots over the threshold, and approach and just hold the "picture" as opposed to other tailwheels which require . stick-this-rudder-that and so forth.
Higher approach speed = Increased directional stability which means reduced short couple tendency to behave like a bag o' squirrels
The Pitts, is, without doubt, the most challenging, and most delightful aircraft I have flown, then unfortunately, I have to land her.............
Higher approach speed = Increased directional stability which means reduced short couple tendency to behave like a bag o' squirrels
The Pitts, is, without doubt, the most challenging, and most delightful aircraft I have flown, then unfortunately, I have to land her.............
Last edited by 7gcbc; 14th Apr 2006 at 13:59.
Why do it if it's not fun?
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An excellent trick for understanding stability on the ground:
Imagine attaching a piece of string to the aircraft's CofG, and pulling it along by the piece of string. Depending on the undercarriage configuration (tail-wheel/nose-wheel, gap between main wheels, gap between main and tail wheel, etc), you can see that some aircraft will be easier to pull along by your piece of string than others. The more difficult ones (tail-wheels, with the two main wheels close together and the tailwheel close to the CofG) will tend to want to turn around and be pulled along backwards - they're the ones which will groundloop most easily.
FFF
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(PS Not sure where I got this tip from, but it's not my own idea so I ought to give credit. I think it may have been from "The Compleat Taildragger", but someone please correct me if I'm wrong)
Imagine attaching a piece of string to the aircraft's CofG, and pulling it along by the piece of string. Depending on the undercarriage configuration (tail-wheel/nose-wheel, gap between main wheels, gap between main and tail wheel, etc), you can see that some aircraft will be easier to pull along by your piece of string than others. The more difficult ones (tail-wheels, with the two main wheels close together and the tailwheel close to the CofG) will tend to want to turn around and be pulled along backwards - they're the ones which will groundloop most easily.
FFF
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(PS Not sure where I got this tip from, but it's not my own idea so I ought to give credit. I think it may have been from "The Compleat Taildragger", but someone please correct me if I'm wrong)
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Originally Posted by 7gcbc
HappyJack,
Thats the one, I think there's only one other 2b east coast, and thats in Victoria somewhere.
cheers
Thats the one, I think there's only one other 2b east coast, and thats in Victoria somewhere.
cheers
You should come try the S-2C at Airborne Aviation, sometime. It's a little easier on landing, and performs quite a bit better in the air, thanks to improved controls and the 3-blade prop.
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Groundlooping
Right on the money Aerbabe!
Coming over the hedge at Old Warden in one of my vintage machines ( especially one of them!) in a blustery crosswind certainly makes me aware of the thousands of pairs of eyes watching for the bounce. I dont usually disappoint...
I have disappointed thus far on the groundlooping front but maybe 2006 is the year....?!
Hairy
Coming over the hedge at Old Warden in one of my vintage machines ( especially one of them!) in a blustery crosswind certainly makes me aware of the thousands of pairs of eyes watching for the bounce. I dont usually disappoint...
I have disappointed thus far on the groundlooping front but maybe 2006 is the year....?!
Hairy
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I haven't groundlooped since my very first landing in a tailwheel ... a Chippy actually. I didn't realise that all the glider pilots on the field had come out to watch just the first landing of several circuits. I only realised later, when they asked whether I was learning ballet. I came close in the Aeronca once - again, I had friends watching. 
At least neither of those get quite the same attention as one of your aeroplanes, Hairy! Promise I'll shut my eyes next time you fly into NW.
At least neither of those get quite the same attention as one of your aeroplanes, Hairy! Promise I'll shut my eyes next time you fly into NW.
Perhaps I should have qualified that with: ".... when teaching someone to fly a taildragger". There´s not one instructor at my old club who has escaped that experience!!
Happy landings
Happy landings
Why do it if it's not fun?
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So if a Pitts is challenging, a monowheel Europa is ???!!
FFF
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