forced landing safety

[schaumr]

Hello everyone,

My name is Rob Schaum, and I am in the final phases of decision-making about which plane to build. Obviously, the COSY MKIV is way out in front, but I guess I'm a bit concerned about forced landing speeds. Some sources are quoting that 'crashes' at 55 mph are more survivable than crashes at 70 mph. I have read that the cosy main gear is supposed to break off on impact to prevent nosing over. I have also read some of the newsletters relating stories of successful forced landings. Can anyone out there add to this knowledge base?

Was this a consideration for anyone of you builders?

 

Other questions:

How does one verify the lay-up quality of workmanship with composites? Do you all just go on faith that each epoxy layer has cured correctly or are there some tell-tale signs to look for? Do you keep the left-overs (in the cups) for inspection after cure?

 

How do you perform maintenance checks on a composite airframe? How can you tell something's amiss?

 

Do you check for 'flutter' during the individual test phase of these aircraft? I know about the problem of overweight elevators, but even when everything balances out correctly, are there any special maneuvers during the flight test?

 

I hope I'm not boring anyone with this...I'm just a curious newbie!

 

Rob

[John Slade]

Hello Rob, welcome!

I just noticed that you're post hadnt received a reply. Let me give it a stab...

 

<snip>

Some sources are quoting that 'crashes' at 55 mph are more survivable than crashes at 70 mph. I have read that the cosy main gear is supposed to break off on impact to prevent nosing over. I have also read some of the newsletters relating stories of successful forced landings. Can anyone out there add to this knowledge base?

Was this a consideration for anyone of you builders?

<end snip>

Check out the NTSB reports. I don't think you'll find many Cozy forced landings. The few crashes there are seem to be mainly pilot error. Also, you might weigh the greater glide efficiency of a canard against the slower landing speed. Its better to glide to a better spot and not have to crash in the first place.

 

<snip>

How does one verify the lay-up quality of workmanship with composites? Do you all just go on faith that each epoxy layer has cured correctly or are there some tell-tale signs to look for? Do you keep the left-overs (in the cups) for inspection after cure?

<end snip>

It's fairly easy to tell that you had a "normal" cure. Scratching the left over epoxy also indicates it's cure quality. The French FAA actually REQUIRE that builders do keep the cups annotated for the part and date.

 

>How do you perform maintenance checks on a composite airframe?

>How can you tell something's amiss?

You tap on it. If there is any delamination you hear a hollow sound. Delamination is a very rare occurance, and is about the only thing that can go wrong with a composite airframe.

 

<Snip>

Do you check for 'flutter' during the individual test phase of these aircraft? I know about the problem of overweight elevators, but even when everything balances out correctly, are there any special maneuvers during the flight test?

<end snip>

I think this is just done by approaching max speeds very carefully.

The main thing is to ensure that the elevators are properly balanced (nose heavy). The Cozy plans address this issue in some detail.

 

>I hope I'm not boring anyone with this...I'm just a curious newbie!

Not at all. Ask all the questions you'd like.

Sorry if you felt ignored.

 

Regards,

John Slade

Cozy IV #757

http://kgarden.com/cozy

[dust]

One thing to remember in building this plane is it is strong, I don't mean just strong I mean STRONG. Every part of the plane ends up being part it's structure. The front seatback is not just a seat back it is a massive bulkhead, the heat duct is not just a heat duct, it is a u channel that adds stifness.

 

It is so strong that one builder, the third in a seriers of builders on a single plane, assumed that the plane that he took over was built correctly, one part wasn't. A very simple item that is clearly marked in tha plans was overlooked by a previous builder in the chain of builders. He probably didn't overlook it, he probably thought he would just do it later, not a good idea in plane building. He did not check the balance of the elevators. Now this is very easy to do, I have done it 4 times as I am building two planes, it was just overlooked.

 

The canard went into full flutter at high speed. Well the pilot pulled the throttle and the stick as the canard was oscilating through a 1 foot arc at the tips in a blur. THE PLANE RECOVERED!

 

Not only that but it didn't damage a thing. A short call to nat puffer, he diagnosed the problem, the fix was easy and the plane and the pilot are flying today.

 

Quality is very easy to determine, the glass is white on the roll, when properly wet out it is clear everywhere and the appropiate amount of epoxy is when you drag a squeegy across the part and no line of epoxy appears when you lift up the squeegy.

 

The plans are organized as a learning tool.

 

Each chapter intruduces you to new and slightly more complex procedures.

 

No extra layups are needed anywhere on the plane and no layups can be ommited, you just follow the plans, it's all there, they even tell you when to go pee, as you will be too busy for a coupla hours so you better do as told.

 

Enjoy and stop by for a day of free instruction, spelled slave wages.

 

Mike

[schaumr]

Thanks guys!

I really appreciate your comments. It helps a great deal!

 

Rob

[niceez]

Rob,

 

Good questions –

I will address each question as you asked them…… Some would be apparent to you if you had a set of plans. First, I have only built sections for Cozy’s (Since I built and fly a LEZ) but having been a professional builder I think I can do this task justice.

 

<<<I have also read some of the newsletters relating stories of successful forced landings. Can anyone out there add to this knowledge base?

Was this a consideration for anyone of you builders?<<<

 

I here this question from time to time and personally am kind of amazed. I think that the answer is obvious. Of course landing at 55 is better then 70 MPH.

But, if you ask most builders, I think they would tell you that they would rather land off field in there Cozy or composite airplane rather then a spam can or so tube and fabric aircraft. You will find this crowd to be dominated by engineers and scientific minded people more then any other homebuilding crowd. And to suggest they are safety conscience is an understatement for the majority. The other big difference is builder-pilot verses buyer-pilot. Some folks tend to give advice without the experience or background to do so. To the point – Most “Forced Landings” as you call them (I prefer off-field since we have to force our planes to land on a runway<Grin>) are largely determined by the terrain you’re landing on. Since our airplanes do not stall, it does give them a margin of safety but the pilot’s abilities have much more to do with it.

My theory is, airliners land at approximately 130 knots, and it does stop people flying on them and most of there off field landing are certain death.

 

 

>>> How does one verify the lay-up quality of workmanship with composites? Do you all just go on faith that each epoxy layer has cured correctly or are there some tell-tale signs to look for? Do you keep the left-overs (in the cups) for inspection after cure?<<<<

 

The plans explain this but to be brief there are two ways. Weight of the lay-up and air-void content. We have known weights for parts and we use a maximum air-void content of 2%. I myself use a maximum of .5% air content and always strive for zero content. Many people do keep there left over epoxy in cups and mark the date and time on them. Tell tale signs of poor workmanship are usually air bubbles in the lay-up and over weight parts caused by too much epoxy.

 

>>> How do you perform maintenance checks on a composite airframe? How can you tell something's amiss?<<<<<

 

We tap the structure with a quarter and listen carefully for the sound to change. A sharp tap indicates a good bond and a dull tap indicates a possible dis-bond or delamination.

 

 

 

>>>>> Do you check for 'flutter' during the individual test phase of these aircraft? I know about the problem of overweight elevators, but even when everything balances out correctly, are there any special maneuvers during the flight test?<<<<<<

 

Probably one of the most overlooked areas is the flight test scenario. Many do not do adequate flight testing. You need to take the plane to the very edge of the line to “PROVE” it can do the maneuver or fly in control at the edge of the box and all perimeters in between. This is a sore point with me because one of the paragraph that has to be attested to is; This aircraft has demonstrated to be controllable through all phases of flight and exhibits no departures from controllable flight. – Or something to that affect.

 

A good place to go is a circular- AC90-89A put out by the FAA. Wouldn’t you know the title is “Testing Your Homebuilt.”

 

The link is: http://av-info.faa.gov/dst/amateur/ac90-89a.pdf

 

Hope this answers your questions.

 

-Dale

[Frank]

One thing I've never really been able to find out is if you can perform any kind of areobatics with the cozy, I'm not talking deardevil stuff here just things like flying upsidedown, loops etc or am i just being a bit of a dreamer.

[niceez]

Frank,

 

Yes you can do light aerobatics, Loops and barrel rolls. But the inverted stuff in any plane requires inverted systems to sustain inverted manuvers. Again, it's a Cozy - Not an Extra 300 or a One Design.

 

The Cozy like the EZ's are very strong. These design's pick up speed far quicker then conventional aircraft and a pilot who is not well trained in this can cause much harm to himself.

 

I suggest you buy a Cozy owner some fuel and breakfest in exchange for a demo ride. Pick someone that will show you a canard stall and some of the different flying characteristics of the canard design. Just remember that the idea of our designs is "economy of flight" and not loops and rolls. We have an amazing group of people here and one of the nicest looking designs in the sky and most of us conduct ourselves as gentleman (sorry gal's, I just didn't want to say ladies). (You'll find the ladies amoung us the best around too!).

 

One more plug. In August I was able to attend my 30 high school reunion (Flew my Long-EZ). At the Hillsboro, Oregon airport, a gentlemen approached me saying he and a friend had built a Long-ez (Just a Cozy on a diet<Grin>) and his friend passed away and the Long was sold and he built a Lancair 320. Just to prove a point to an old classmate I said, "Ever sorry you sold the Long-EZ." He replied, "Every day since I flew the Lancair." Not to say that the Lancair is bad, it's just that I find people tend to really miss the fine qualities of the canard design.

 

Hope this helps.....

[Jack Wilhelmson]

The Cozy/LongEZ airplanes will not fly upside down. The reason they will not is that they do not have sufficient down(up when the airplane is upside down) elevator travel to hold the nose level with the horizon. So any attempt will end up in steep dive up side down. The wing is not a symetrical airfoil and therefore will require quite a high angle of attack to keep the airplane in level flight. The elevator has only 15 degrees of down travel and this is not enough.

 

A axial roll can be done if the speed is high and the airplane is put into a good climb before executing it. Otherwise the nose will drop and split S will result with a very high speed recovery. Could spoil your day.