Can a PA28 with a detatched engine glide?

[18greens]

If the engine detaches from the airframe of a PA28 (say following a prop failure), is there enough elevator authority to maintain the aircraft in a glide following the rapidly aft movement of the CofG?


Does anyone know?

[Tone]

I thought it was illegal to drop things from aircraft in flight.

[IO540]

I guess there could be at cruise speed (because elevator authority goes up as the square of the ias) but you would have to maintain the speed all the way to touchdown... might mean a forced landing at 100kt+

[18greens]

Tell that to the engine.

[Saab Dastard]

I don't know about the whole engine detaching, but I've seen a photo of a PA28 that lost the entire prop, spinner and a goodly chunk of crank / driveshaft and made a successful forced landing.

Hat's off to the pilot.

From my experiences with model aircraft, powered and unpowered, I would be surprised if the aircraft were flyable without the mass of the engine. On the other hand, it would take massive force to dislodge the engine, so I suspect that it being flyable would be somewhat academic!

I recall a fatal accident in a glider (Libelle, I think) which was being flown solo by a petite woman in the rear seat. The investigation indicated that the ballast in the front cockpit wasn't restrained properly and slipped to the rear cockpit, with the resulting alteration of the CofG being sufficient for a stall spin accident.

SD

[bluskis]

Calculate the CofG position without the weight of the engine, this should tell you if you are still within the envelope. My guess would be you will be outside the limits.

[IO540]

While this is clearly a hypothetical scenario, the problem with checking the W&B envelope is that the published envelope is based on the elevator authority at the published stall speed. The elevator authority will be a lot higher at a higher speed.

[Flyin'Dutch']

Given the weight of the engine and the place of it I am sure that you can not fly most singles once the engine has departed.

Stick it in your W&B equation and you will see what I mean.

FD

[Stampe]

A Miles Messenger flown by one of the Miles test pilots with his family on board lost its engine completely whist flying over France back in the fifties .He moved his family as far forward as possible and made a satisfactory forced landing.I,ve seen a picture of the engine-less airframe so it is possible!!.:ok:

[18greens]

Is it a hypothetical scenario?

If part of the propellor detatches the eccentric weight could dislodge the engine. It happened to a twin in the UK about 10 years ago. As I recall the aircraft entered a spin which the pilot recovered from and landed.

I also agree with IO540 that the despite the fact the CofG is probably out of limits it does not necessarily make it unflyable. After all people must fly aircraft out of offical CofG in the same way they fly them over MAUW. They still take off (but not legally). The structural limit will be higher than the published limit.

I guess it comes down to where the CofG ends up and how much force the tailplane can produce to counter the pitching moment (and at what speed).

Thinking about it the cofg would be aft of the cofp making stability interesting as well.

[Flyboy-F33]

That is one very good reason to not skimp on prop maintenance.
I was told that if a prop blade came off, the engine would depart before you could shut it down. As a result the aircraft minus engine would be unfliable due to limited elevator authority.

I dont think a survivable landing (in a single) would be an option.

GG

[HectorusRex]

The Engine is Missing!

In the vicinity of New Plymouth, New Zealand, in March 1958 a Cessna C-180, ZK-BQJ engaged in aerial topdressing suffered a propeller failure which threw one blade.
The resultant imbalance then threw the engine completely out of the airframe almost instantly.
As it departed the engine forced the top cowling over the windscreen, and also impacted the starboard main-wheel, cutting the tyre.

The moment the engine came off the Cessna was thrown into a vertical snap roll, so rapidly that the pilot’s crash helmet was cracked when hitting the windscreen pillar!
Then followed a flat spin, from which normal spin recovery was successful.

To counter the pitch-up resulting from the rearward c of g change, the pilot applied full forward elevator, and lowered the flaps.
The ensuing flight path was controllable sufficiently to affect a successful force landing, with no further damage to the aircraft.

The free flying engine impacted in the farmer’s wood pile with no other damage to any person or property, but gave the farmer’s wife a severe fright as she hung out washing.

After a calming cup of tea, the pilot checked in with his operating company and reported that he needed a replacement aircraft, and when asked why, responded that the engine was missing.
“Have you checked the plugs?”
“No point, I can’t even find the engine!”
They took him at his word and duly arrived in a replacement aircraft, complete with engineer ready to replace plugs etc!

The pilot became a legend in New Zealand agricultural aviation circles and managed to successfully complete in excess of 25,000 hours topdressing time.

Sadly he passed away a few years ago in retirement.
Vale, Don “Goose” Ercerg.

[Flyboy-F33]

amazing.......!

[sunday driver]

Now this is getting REALLY interesting !

Could one of the aerodynamics experts out there comment on my rather amateurish guess at why the NZ hero was able to recover the situation . . .

1. Full down elevator to reduce the downforce from the tailplane, and maybe generate some upforce. Helpful to add full nose down trim I guess.

2. Full flap, which on a high wing Cessna produces a significant nose-down attitude, presumably by moving the centre of lift aft (I guess you wouldn't get a similarly comforting result in say a PA28, or a Robin DR400), and move all occupants/lbaggage as far forward as possible.

3. As previously stated, increase airspeed if poss., to improve elevator authority.

4. Turn fuel taps off . . .

Now don't point your shotguns at me, I'm no professional. Just an interested guy. Tell us some stuff which one of us may be grateful for one day, like how could we get away with this situation in a PA28 or 38 ?

SD

[High Wing Drifter]

I imagine that with the resulting rearward movement of the CofG, possibly beyond the Centre of Pressure (CP) that the a/c would become extremely unstable, requiring the lightest of touches to alter its attitude, surely it would be virtually uncontrollable by human hand. The usual downward force exerted by the tailplane in S&L would now require an upward force to prevent a nose up. As SD says, with the flaps deployed, the CP will move forwards a bit, but now with no thrust and a shed load of drag. The only good thing is that the stall speed should be lower and glide longer as the tail plane is required to provide some lift too lessing the load on the wing.

Was reading a ILAFFT book on the tube the other day, had a story of a twin whose starboard engine fell off, the specific problemin thise case was that the engine stayed attached via the control and instrument cables but now about six feet aft of the wing!!!! The drag was such that the only way was down at 500fpm. Nothing but forest for miles around, made a successful forces landing in a shallow river!!!! Amazing.

[montys ex teaboy]

Yes I remember the incident of the C 180 well. However my take at the time was the CG was so far aft of the datum, therefore uncontrollable, it was the "grace of God" alone that got Goose down in one piece. I get the impression the thing just fluttered backwards and forwards and it happened to hit the ground at a time when the vs was at a minimum.

This is not to say that Erceg was not a great pilot and a lengend, because he was.

Very sad to hear of Goose's parting. He had used up most of his 9 lives when I knew him, in the early 70's.

[MLS-12D]

I doubt that there has been extensive (or any real) testing, but if the engine departs the aircraft, I think that we may safely assume that 99% of the time, the CofG will shift so far to the rear that the airplane will be essentially uncontrollable. :eek:

I recall a fatal accident in a glider (Libelle, I think) which was being flown solo by a petite woman in the rear seat. The investigation indicated that the ballast in the front cockpit wasn't restrained properly and slipped to the rear cockpit, with the resulting alteration of the CofG being sufficient for a stall spin accident.Perhaps you are remembering this Blanik accident (http://www.glidingmagazine.net/FeatureArticle.asp?id=173)? I don't know of any twin-seat Libelles.

[Right Stuff]

sunday driver, as a former aero eng student I concur with your theorising. However, I would agree with 99% of people here that the aircraft would be uncontrollable. Rudimentary analysis of the moment a heavy lycoming contributes to the a/c would lead me to believe that you'd be getting the prayer matt out.

As stated in the earlier story, I'd wager a departure so rapid you wouldn't know what had happened followed by an unrecoverable descent either spinning or tumbling.

[FNG]

If my engine jumps out, I'm jumping out after it (see the current thread on parachutes, which has extended beyond aeros).

[HectorusRex]

In a conversation I had with "Goose" very shortly after his incident he proffered the suggestion that he reckoned he had sufficient control to have attempted a turn, " if he had been cheeky enough"!

[Shaggy Sheep Driver]

1. Full down elevator to reduce the downforce from the tailplane, and maybe generate some upforce. Helpful to add full nose down trim I guess.

To increase the effect of the 'down' elevator, you need 'up' trim. the trim tab would then be 'down', and adding to the 'down elevator' effect (and increasing the the load for the pilot!). 'Up' trim would decrease the 'down elevator' effect.

And in all the Cessnas I've flown, putting down flap results in a nose-up trim change. Surely not what is wanted in this situation?

SSD

[High Wing Drifter]

And in all the Cessnas I've flown, putting down flap results in a nose-up trim change. Surely not what is wanted in this situation?
Nose up??? Flap reduces AoA! Trim as required.

[dmjw01]

As SSD says, whoever mentioned flaps didn't quite have the right idea. They said (quite correctly) that it results in a "nose-down attitude", but this is only achieved after you've dialled in a lot of nose-down trim to counteract the rather substantial tendency to pitch UP.

If you doubt what SSD says, try doing a go-around in a Cessna from full flaps, but be ready to push forward really hard!

[High Wing Drifter]

If you doubt what SSD says, try doing a go-around in a Cessna from full flaps, but be ready to push forward really hard!
Not sure that's the same thing: If you do a go-around in such a situation you should have a reasonable amount of nose-up trim to maintain the right glidepath and speed. Adding more power to the equation, and hence speed, will of course bring the nose up and require considerable force to couter...with or without flaps. Nose trim down for the new speed is of course essential.

[Shaggy Sheep Driver]

Why the mystery? It's simpler than that. From a trimmed condition, put down some flap in 150/172. The nose will rise (putting down flap gives a nose-up trim change!). You will need to counter this with forward stick, then forward trim to take away the stick force.

Isn't this basic stuff, or am I missing something?

SSD

[High Wing Drifter]

To quote SD:
. Full flap, which on a high wing Cessna produces a significant nose-down attitude, presumably by moving the centre of lift aft
This is true for stable flight. What you say is true the instant you slap flap on. Not the same thing.

[montys ex teaboy]

Depending on the amount of flap and the type of A/C, high or low wing, then the angle of the airflow as it strikes the stabiliser can also have a great effect on trim, which tends to push the nose up. Especially with the initial stages of flap.

[ft]

HWD had it nailed though. The (primary) problem is not with control authority but with stability. Chances are you'll be flying tail first in an instant... and this will not depend on your airspeed. :/

Cheers,
Fred

[sunday driver]

Staying with the high wing situation,

the issue of instant and terminal uncontrollability did not seem to apply for our NZ hero, so how did he manage it, and why?

and the suggestion that he was lucky to hit the ground when his C180 had fortuitously decided to twitch upwards a bit is denied by his own (second hand) evidence (see above).

The "going around" trim change doesn't apply here because the trim change is required to counteract the thrust of the engine (which in our case, we do not have . . . ) at full power acting in concert with the centre of drag

SSD's assertion about needing to point the trim tab down is well made, and in this situation I'd be happy to lean on the control column for a bit, whatever the stick forces

Also, now we're without the engine, the CofG has obviously moved rearward, BUT also Upwards, and now resides just behind the trailing edge, perhaps in line with the wings & tailplane.

The point is, the man walked away - and did the flaps make the difference? how? why?

SD

[montys ex teaboy]

Just to add a little to the discription of the Cessna incident, so well put by HectorusRex.

I believe if memory serves me correctly that the A/C had just become airbourne, no load and the prop blade was discarded at approx 150ft.

[HectorusRex]

montys ex teaboy's recollection is as I understood the event to have occurred in my conversation with Goose very shortly after this incident.
I'm certain that he made no mention of using trim, as in the early C180's this was a very slow manual operation, and he would have had both hands full.
I seem to recall him mentioning using his knees to assist in getting full forward control column!
More than a little luck went his way.

[sunday driver]

Ah well, another good story scuppered by gratuitous facts.

Still, those 150 feet must have seemed horribly high.

SD

[englishal]

Nose up??? Flap reduces AoA!
Eh :confused: