What would you do?

[Captain]

The only thing it can be is that extra weight (but not extra total mass needing retardation) on a particular wheel will stop that wheel from locking due to greater friction. Witness that [all things being equal & ABS not fitted] (race) cars will lock the inside wheel when turning into a corner if still under brakes, as the weight comes off that inside wheel .... and the back wheel of a motorcycle will lock more readily than the front under heavy braking.

 

 

 

But then again, I are not a sign-tist.

 

 

 

[Guest browng]

The only thing it can be is that extra weight (but not extra total mass needing retardation) on a particular wheel will stop that wheel from locking due to greater friction. Witness that [all things being equal & ABS not fitted] (race) cars will lock the inside wheel when turning into a corner if still under brakes, as the weight comes off that inside wheel .... the the back wheel of a motorcycle will lock more readily than the front under heavy braking.

That makes sense, I don't think I have ever had to brake an aircraft hard enough to lock the wheels except when finally parking it. I wonder if the average aircraft brakes are powerful enough to lock while still moving at speed? That might be a 'negative feature' for a tailwheel aircraft, as you could easily put it on its nose, or at least suffer a prop strike.

 

 

[slartibartfast]

As Captain suggests, the extra weight on the wheels gained by putting the flaps away (and therefore reducing lift) gives the wheels more traction on the surface. Especially noticable on a wet surface. I was taught to retract flaps even on a dry bitumen runway to reduce the chance of a wheel locking (possible even with the average feeble aircraft brakes) if you want to pull up quickly.

 

I think Nev was suggesting that you use the flaps to lower the stall speed and increase drag and descent rate until you touch down, then retract for the extra braking. If he wasn't, I am.

 

While I'm wading in, I would avoid the fence. It might break and slow you nicely, or it might not and slice you nicely. If there's paddock on the other side, I might try an old hang gliding trick (if I had practised this on type). Conserve some energy before the fence and flare over it. Although I watched a friend slightly mis-time this once and tear the bum out of his jeans on the barbed wire. Timing is everything.

 

 

[Guest browng]

Conserve some energy before the fence and flare over it.

Sounds good for a hang glider, but I'll take the fence thanks, if you get that wrong and strike the wire with the U/C, you could find yourself upside-down and smelling of petrol.

 

 

[John Brandon]

Not personally, but my first piper Cub, G-BPPV, (which after I sold it went to Ireland and became EI-CUB), was but through a stone farm wall with only minor injuries to the 1 of the 2 POB. photo below.

 

 

Thanks for the information George but I'm after a short "this is what happened to me" description from someone who has opted to go through a well maintained barbed wire fence.

 

For those who are interested the following is an extract from a detailed incident report by a Boorabee pilot who did everything right in a forced landing:

 

"... the positioning and timing seemed to come together almost at a crawling pace, but it must have been just a few seconds. The turn onto final had to be made at low level so I made a definite intent to ensure good speed into the turn. Turned onto the final approach high enough to clear the barbed wire fence and fast enough to have full control and touched down beyond the fence parallel with the ploughed furrows ... recall pushing the nose down just enough to ensure longest distance possible for ground roll as the dirt paddock would retard the motion a lot faster than flaring and easing onto the ground halfway up the paddock ... noisy and bumpy ride with underside of pod sliding along top of furrow ... GROUND LOOPED TO HALT THE AIRCRAFT WHEN GETTING CLOSE TO THE END FENCE ..."

 

Regarding braking I recall that the Aircraft Research and Development Unit at RAAF Laverton liked to demonstrate their short landing technique for their Dakota [DC3] which was to push forward on the control wheel at touchdown with full [max. drag] flap deployed holding the tail right up, so minimising aoa and thus lift and so putting max. weight on the main tyres [ increasing their contact area and runway-tyre friction]. The pilot then stood on the brakes which brought the aircraft to a halt very quickly — the tailwheel made contact when the elevator authority was insufficient to keep holding the tail up. This of course was on a hard runway, don't remember what they did on wet or frosty grass.

 

cheers

 

John

[facthunter]

Braking.

 

It's generally accepted that weight on wheels is the big consideration. Of course we are assuming that you have brakes that work. If you are still part flying the tyres just make smoke. A tailwheeler can , with hard brake application, end up on its nose, if you keep the brakes on when the speed has diminished and the tail has risen beyond the point of no return. As an example of a technique to demonstrate the principle of putting weight on the wheels, the DC-3 emergency stop on take-off was to put the stick full forward and apply max brake without wheel lock-up. If this was done without a certain finesse, the propellers would contact the ground. Locked brake equals blown tyre very quickly on sealed runway, without anti-skid. At decision point the weight on the wheels in the normal attitude, is virtually zero as the aircraft is ready to fly off the runway. No weight- no friction Nev..

 

 

[Guest browng]

A tailwheel can , with hard brake application, end up on its nose, if you keep the brakes on when the speed has diminished and the tail has risen beyond the point of no return.

You ain't kidding, I have seen a tail wheel aircraft end up on it's nose with NO braking at all, just from allowing the wind to get under the elevator when taxying. It is going to depend on the moment about the undercarriage, some types will have a CofG well aft of the gear, others less so. It would take a serious effort to put the J3 on its nose, but a DH84 retro-fitted with brakes will do so very easily, it wasn't designed to have them in the first place. So why don't all tailwheel types have a CofG a long way aft of the gear? Because the downside of that is greater momentum in the swing, and a more difficult recovery.

 

EDIT - It's not just tailwheel aircraft either, over-enthusiastic braking can even put a tri-gear on its nose, note that this bloke has his flaps down and still managed it, he braked so hard he collapsed the nose wheel. Aircraft are not cars, overly powerful brakes are a BAD design feature. Even the J3 which I have already said is difficult to put on its nose with the standard expander brakes, (very difficult to get parts for these now), is very easy to up-end when retro-fitted with disk brake kits as many now are due to the rarity of the original item.

 

 

 

[facthunter]

C of G & Main gear location.

 

Yes, true browng. Good pics there. Brake (& tailWHEEL in lieu of SKID) equipped Tiger moth had the main gear located forward of the normal (unbraked) DH 82 and for the reason that you state . It was however, considered to be a "dog" compared to the normal tiger because of its directional instability. I see a lot of pilots taxying in fairly strong winds with no real regard for position of controls. I think they are trying to keep weight off the nosewheel, but in a downwind situation, thats not too clever. (full back stick.) Nev..