Speedbrakes on a Cessna 172...
 

A thought popped into my head about forced landings...

For the sake of discussion, let's assume a 'best' worst case scenario: engine failure at a reasonable altitude (say, 5000' AGL). Landing site chosen (a field or a lake, you pick). Engine out / descent checklists completed... and an experienced pilot.

When arresting the rate of descent before touchdown over uncertain (bumpy, pitted, etc)terrain, what would be the effect if the front-seaters not only unlatched the doors (as in the checklist), but also pushed the doors into the wind a la speedbrakes?

Let's assume that both doors are opened equally so there is no induced yaw. Would the opening of the doors slow forward velocity enough that, combined with the arrest in the rate of descent during the "flare," impact forces would be minimized? Or, perhaps over water, could this possibly slow the airplane to the point that it more nearly 'falls' into the water at a low speed from a very low altitude, reducing the possibilty that the aircraft will cartwheel when it goes into the drink?

Just something to think about. I know that it's not practical, and it goes against the first rule in an emergency - "Fly the airplane!"

I just wanted to hear other pilots' opinions on this... :)

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-Plap




[This message has been edited by Plap (edited 12 June 2001).]

Assuming you manage to make the doors the perfect speedbrake... you'd reach stall speed faster and that would be it. At Vs, down you go. Speedbrakes just add drag, make you bleed energy faster and move your touch down point closer.

Perhaps if you find yourself headed for a treeline...

Cheers,
/ft

I knew some larrikans who tried this in a C152, in normal flight, it used to definitely reduce speed rapidly, anyhow they tried in a steep climb and the C152 slowed to a stop then tailslid backwards and ripped both doors off! So I mean, it works but there not exactly designed for it......

They already have spedbrakes on the 152...its the last 15 degrees of flaps.

Seriously, have you ever had the door pop open in flight on a 150 or 172? Rather than messing around with door as speedbrakes just learn to do a forward slip.

AoA: Doesn't sound like the safest thing I've ever heard, but still funny nonetheless :)

Ratboy: Yes, I've had doors pop open during takeoff / upwind. I wasn't suggesting that anyone actually try using the door as a speedbrake - as you pointed out, they are quite non-essential on 152/172's...

-Plap

Had an instructor demonstrate steering with the doors in a 152 once :)

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Per dementia ad astra

Know a guy who got a 172 home once steering with the doors. Happened when I was a student pilot. Cannot remember the exact scenario, but I believe there was a control cable failure.

It's interesting just how much roll/yaw control authority there is using the doors alone in C150/152/172.

Funnily enough, the a/c rolls/yaws away from the door that is opened & pushed slightly into the airstream.

Properly trimmed, you can even land a 152 using doors and throttle only. Did it twice... :)

But the fasted way of losing altitude in a Cessna is to use full flaps and slip.

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100% human beef drilled to perfection

Some thoughts -

(a) have you ever tried to push open a door in flight ? I had a door unlatch on an Aztec years ago with only me in the aircraft (and, yes, I did latch it correctly - a maintenance related problem). I had a dickens of a time to get the door relatched. Trying to push it open in other than significantly yawed flight conditions was pretty well impossible - and I am talking only an inch or two.

(b) with a flying tailplane, pitch oscillations are disconcerting and I understand that this is a pretty general observation.

(c) why would you want to use speedbrakes in a forced landing situation other than to correct a misjudged glidepath ? Sideslip is much more reliable I would suggest

(d) I would be far more concerned with poor flightpath control and unintended stalling whilst playing with the doors.


or is this thread just a wind up ?

all piper drivers, save yourself the hernia and open the storm window before you try and shut the door.

<--first hand experience

Re aztec doors,
yes the storm window helps but doesnt cure the problem.
When the door pops the aircraft yaws and one puts on rudder. The problem for most normally designed pilots you can't reach the door and keep the rudder pressure.
The sideslip, yaw, rudder pressure and reaching the door which is at least a foot open is a challenge !
Of course having a passenger would help !!
It also happens after takeoff so you have to climb if you want to mess around !

I read an article in some mag or other where a guy reckoned he'd recovered a 152 from a spin just by opening the door.

Also, an Instructor of mine force landed back on at Rand (SA) after the door popped open just after take off. The same guy was killed last year in a freak accident along with another Instructor and a passenger when the C185 they were flying spun in shortly after take off. Last I heard it seems that the pilots seat may have sheared its attachment rivets which (allegedly) should have been bolts !!

Sorry, meant to say the door opening incident in my last post was in an Aztec.

Surely a bit dramatic to force land just because of a popped door ? Admittedly, with a flying tailplane, the pitch oscillations with a popped door are quite alarming, but not at all difficult to control

JT,
For info the early Aztec's just had a single spring latch in the middle of the door ( as in a car) The problem was that when the latch got worn and the door flexed it would pop open. Hence the number of incidents !
Later this was modified and added an additional positive latch at the top corner of the door which seemed to cure the problem.

Slightly off the thread (but in sympathy with it) I was flying with a friend over Cape Cod in a 172, when he started to open the RH door window catch to get a better picture with his camera!

I stopped him before he got the window opened, but have always wondered if the slipstream would have removed it as its only held on by a "piano lid hinge"

Anyone with personal experience?

PS: I now always include windows in my safety brief (if they open!)

[This message has been edited by Final 3 Greens (edited 26 June 2001).]

Final 3 greens, i've quite regularly opened the windows on Cessna singles and I haven't lost one yet, does slow you up a bit but it certainly increases the airflow on a warm day !

Puff & final 3, windows open are not a problem, except this time of year in Canada when it could cause pilot & pax to freeze their @$$es off. The POH gives a maximum windows open speed that is the same as Vne.

Final 3 Greens. .. .Often flew with the window/s open on C180's during SAR or photographic opertions. Good idea to remove the window strut screw - it will eliminate the load on the window frame where the strut connects. The window will ride in the airstream at the near horizontal position and afford an excellent, uninterrupted view.