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I picked up my plans in about '82. The things that sold me on the design was it's stall characteristics but mostly it low drag characteristics. When you can climb quickly to altitude, chances are you will. That makes it easier to cash in on the ablity to reach an airfield 20-25 miles away from an altitude of 10K. When I compare those characteristics to the Archer I typically fly (which doesn't have half the range from that altitude) it makes for a substantial option.

Yes, Burt had talked about the anti-stall of the main wing on the Varieze during his seminars at the Corona, Calif. fly-ins during the '70's. And he also used to fly his Variviggen to the Flabob Fly-In in Rubidoux west of Riverside.

He flew his Viggen to Corona one year and had to land on one main and the nose gear. Mike was the one to design and build a more reliable retract system for the Viggen.

WT Johnson

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The only thing that's going to save your bacon is that safety device housed by your headset.

I'd rather be sitting at 9500' in a slick aircraft with a good moving map than working with the tools available in a slow aircraft. Sure you can land a Cub at low speed ......... but my aircraft has a better shot at making the field.

There were a fair number of aircraft who crashed due to an engine-out on final approach. But I too wish you luck.

 

Beyond the KE of landing, our EZ aircraft have a tendency to tip over offroad.

 

There are several (many?) instances of Ezs having a brake or tire problem that dragges them off to one side of the runway---usually either destroying the landing gear and/or tipping over.

Mostly these incidents didn't end in fatalities (I may be wrong, but I don't recall that any of them did).

 

There were an awful lot of the taildraggers being damaged by ground-loops. But the damage was more to the airframes than to the person, so these types of accidents don't personally concern me greatly.

 

On a personal level, unlike WT Johnson I don't have a plane built, so I'm trying to come to a conclusion about the relative risks. Certainly not decided against... These aircraft have a mix of frugality and performance that is certainly compelling.

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There were a fair number of aircraft who crashed due to an engine-out on final approach. But I too wish you luck.

Really!?

......and did they have the landing brake deployed or retracted?

 

I was on a skydive demo team for six years so I am familiar with high-pressure problem solving.

 

One of the most impressive demostrations I read about was the one where they crossed the nubers, shut off the engine, did a 360 and landed on the same runway......... but I'm sure they did not have the landing brake deployed.

T Mann - Loooong-EZ/20B Infinity R/G Chpts 18

Velocity/RG N951TM

Mann's Airplane Factory

We add rocket's to everything!

4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done

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Really!?

......and did they have the landing brake deployed or retracted?

 

I was on a skydive demo team for six years so I am familiar with high-pressure problem solving.

 

One of the most impressive demostrations I read about was the one where they crossed the nubers, shut off the engine, did a 360 and landed on the same runway......... but I'm sure they did not have the landing brake deployed.

Dick Rutan in his LongEZ used to do a demo at airshows. He would come over the end of the runway at a pretty good speed, shut the engine off sometime during the final, make a 360 and land. I always thought that was pretty impressive.

WTJohnson

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I often use statistics in the field of finance, but in application it doesn’t take long to figure out that statistics can be very simplistic. Qualitative information is far more valuable when mixed with good judgment. For example, if the statistics say that Long-Ez’s are less safe than Cozy’s I would question the value of that data. Perhaps the statistics are really saying that Long-Ez pilots are less safe than Cozy pilots. I imagine that the pure speed and performance freaks in the canard group elect to go with the Long-Ez while the guy who wants to take the wife and kids for weekend vacations would go the Cozy. I would venture to say that the speed and performance freaks are far more likely to push to envelope than the guy with his wife and kids in the plane. Therefore, the stats may say nothing about the plane; rather they indicate something about the typical pilot of that plane. If you are one of those safe pilots then flying a Long-Ez or any other aircraft doesn’t have to be any more risky than flying a Cozy.

 

I am sure you can spot the pilots who will tend to have “incidents” a mile away. I am sure it is always the same pilots generally have these incidents while there are others who never have a single incident after decades of flying.

Crazy Canuck

Toronto, Ontario, Canada

Cozy MKIV #MK1536

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There were a fair number of aircraft who crashed due to an engine-out on final approach. But I too wish you luck.

 

Mostly these incidents didn't end in fatalities (I may be wrong, but I don't recall that any of them did).

 

 

Sorry---I was answering the below question and not saying that they were fatal----should have quoted it so that it was not confusing:

<snip>There were also an alarming number of unexplained accidents where the plane veered off to one side for no apparent reason, then crashed the ground whilst on its side or inverted.<snip>

 

<snip>Therefore, the stats may say nothing about the plane; rather they indicate something about the typical pilot of that plane. If you are one of those safe pilots then flying a Long-Ez or any other aircraft doesn’t have to be any more risky than flying a Cozy. <snip> It is not that difficult (but somewhat time consuming since you have to actually read the account in the database) to determine if you have a pilot or aircraft problem. For instance, things like running out of gas, hotdogging over someone's house, or inadvertant IMC definately fall into the pilot category. Electrical and fuel systems failures probably fall into the builder or maintainer category. Structural failures may fall under the aircraft---but most likely into the builder category (were plies left out?). Offroad landing characteristics most likely fall under the aircraft.

 

If you actually do the work to study it (Longez and Cozy in particular), I think you will find lots of pilot errors. When there are not pilot errors, you will find lots of system problems which were most likely builder or maintainer induced. You will find some problems due to "quirkiness" of the design----high speed landings and "tippy" behavior. I believe that you will find no structural problems due to a properly built Longez/Cozy(or Varieze). You have the one wingbolt failure in a Varieze where the guy did not use the right bolts. There was a Longez winglet failure where the builder only had half the plies. There was the Varieze canard flutter failure where they still had overweight elevators (the old "elevator within an elevator" mod that Rutan disallowed).

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I often use statistics in the field of finance, but in application it doesn’t take long to figure out that statistics can be very simplistic.

I agree... To a point. I'm a scientist and I know the literature is crammed with papers showing statistically significant effects that I don't believe in. The real questions are 'how large is the effect' and 'is it larger than the unknown error terms'. As the unknown error terms are, by definition, unknown there's always a degree of subjectivity in their assessment.

 

So I agree about being cautious, but I still think statistics can provide an useful starting block. If one aircraft has 25% more fatal accidents than another then I don't see anything in it - even if it's statistically significant. If one type has 5 times more fatalities than another then I think you have to work hard to think of reasons why that should be.

 

When I picked on forced landings, I was trying to count out pilot attitude issues. Obviously if you're assiduous about engine maintainence you can reduce your chances of having to make a landing, but once the prop stops you're committed to a hazardous landing - however careful you are the rest of the time. It may well be that Kitfox pilots are more used to landing in rough airstrips and therefore make a better job of forced landings. On the other hand, a high-flying Long-EZ should perhaps have a better choice of landing sites. What I would bet is that every pilot in a forced landing situation makes the best job he or she can.

 

When I have time, I'll look at some more slow-flying types and see if the pattern still seems to hold.

 

If you are one of those safe pilots then flying a Long-Ez or any other aircraft doesn’t have to be any more risky than flying a Cozy.

All aircraft are equally safe..? No way.

 

There's a dictum that flying is safe, but very intolerant of mistakes. This is nonsense. We're all human. We all make mistakes. And I think it's inarguable that some aircraft reprimand mistakes more harshly than others.

 

When I was learning to glide, I had a very near miss when a thermal picked up my wing and swung me towards the hill. I was flying an old training glider that had a relatively sharp stall and not enough control authority at low speeds. After I landed (and was unfairly reprimanded for having chosen to make a turn towards the hill rather than away from it) several other pilots told me they'd had trouble with that glider, and one had had a similar incident.

 

The experience persuaded me to invest in a considerably more expensive glider, that had much better handling. Safer? No statistics, but I'm convinced. The other moral of the story was that had I died (and I came extremely close) the accident report would undoubtedly have said 'inexperienced pilot chose to turn towards rather than away from the hill: pilot error' when the real issue was a glider that was structurally sound, whose flight characteristics were fully known (albeit too exacting for a student pilot) but which was basically not fit for purpose - at least by modern standards.

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Really!?

......and did they have the landing brake deployed or retracted?

 

One of the most impressive demostrations I read about was the one where they crossed the nubers, shut off the engine, did a 360 and landed on the same runway......... but I'm sure they did not have the landing brake deployed.

I'm not sure that's really relevant. I gather Rutan used to start the maneuver at 120 knots. Hardly normal landing speed.

 

If you normally make a landing approach with the engine on, as I see it any engine failure will cause you to land short unless you can reduce the drag configuration of the aircraft in response to the engine cutting. Or unless you were landing faster than optimal. Or unless the engine was producing no appreciable power whatsoever - perhaps this is possible; I don't know?

 

So do you normally land the LongEz with the airbrake on or whilst sideslipping?

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If you normally make a landing approach with the engine on, as I see it any engine failure will cause you to land short unless you can reduce the drag configuration of the aircraft in response to the engine cutting.

In the situation you are quoting, the proper response is to retract your gear and landing brake until you have the field made. It's the induced drag that makes it possible to follow a normal glide slope.

So do you normally land the LongEz with the airbrake on or whilst sideslipping?

Yes, and sometimes deploying both rudders at the same time to create even more drag. Without such measures your glide slope would be too shallow for most runways.

T Mann - Loooong-EZ/20B Infinity R/G Chpts 18

Velocity/RG N951TM

Mann's Airplane Factory

We add rocket's to everything!

4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done

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I agree...

 

 

 

All aircraft are equally safe..? No way.

 

 

Safety of an aircraft has many factors which must be taken into account (including type of pilot) when trying to compare one to another.

 

Our aircraft have a relatively high lading speed, higher, in fact than many high performance store bought types.

 

Higher than ultralights also.

 

Part of the increased risk in the e-z types is that speed. VGs tend to bring the landing speed down to that of a Bonanza, Mooney Cirris or Cessna's glass.

 

An engine out experience at a similar altitudes will yield interesting results.

 

If a low altitude, the ultralites and trainers will do better. As the landing speed increases the safety of the aircraft with engine out decreases.

 

At 1000' with no engine, would you rather be flying a weedwacker or a lear jet?

 

At 2000' same question

 

At 3000' the answer changes quite a bit. We just had a successful landing of an airbus just yesterday under these circumstances. (certainly not a low landing speed aircraft)

 

At 5000' chances are, with equal piloting skills most of the aircraft would be able to land safely (assuming appropriate landing areas available)

 

At 10,000' All aircraft would have the opportunity to land safely independant of their landing speed.

 

I will never forget William Wynne (of Corvair conversion fame), at a Dragonfly fly-in musing about how the higher landing speed of the D-fly approx 70 is so dangerous, and that we should all be flying pietenpols (some liberty taken with the misquote) and we would all be much safer. Good thought, except he almost perished in a Piet accident and subsequent fire shosrtly after that. (fortunately he is now OK)

 

If you are going to compare aircraft, you must compare apples to apples.

 

Perhaps comparing all aircraft with similar landing speeds would be a good start.

 

It would also be more significant if the altitude of the engine failure/ reason for the less than goo landing is taken into account.

 

The real question is that with an engine failure or other forced landing situation in aircraft of similar landing speed, at similar altitude, What is the compairative damage/fatality rate. Other data points although interesting seem to be somewhat trivial.

 

Until we change the laws of physics (as we know them) if we want a high performance, economical(?) aircraft, we must compromise by the higher landing speeds. If we are unwilling to compromise, by all means get/steal/build one with much lower landing speed and the increased safety that MAY be gained.

I Canardly contain myself!

Rich :D

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Safety of an aircraft has many factors which must be taken into account (including type of pilot) when trying to compare one to another.

 

Our aircraft have a relatively high lading speed, higher, in fact than many high performance store bought types.

 

Higher than ultralights also.

 

Part of the increased risk in the e-z types is that speed. VGs tend to bring the landing speed down to that of a Bonanza, Mooney Cirris or Cessna's glass.

 

An engine out experience at a similar altitudes will yield interesting results.

 

If a low altitude, the ultralites and trainers will do better. As the landing speed increases the safety of the aircraft with engine out decreases.

 

At 1000' with no engine, would you rather be flying a weedwacker or a lear jet?

 

At 2000' same question

 

At 3000' the answer changes quite a bit. We had a successful landing of an airbus just yesterday under these circumstances. (certainly not a low landing speed aircraft)

 

At 5000' chances are, with equal piloting skills most of the aircraft would be able to land safely (assuming appropriate landing areas available)

 

At 10,000' All aircraft would have the opportunity to land safely independant of their landing speed.

 

I will never forget William Wynne (of Corvair conversion fame), at a Dragonfly fly-in musing about how the higher landing speed of the D-fly approx 70 is so dangerous, and that we should all be flying pietenpols (some liberty taken with the misquote) and we would all be much safer. Good thought, except he almost perished in a Piet accident and subsequent fire shosrtly after that. (fortunately he is now OK)

 

If you are going to compare aircraft, you must compare apples to apples.

 

Perhaps comparing all aircraft with similar landing speeds would be a good start.

 

It would also be more significant if the altitude of the engine failure/ reason for the less than goo landing is taken into account.

 

The real question is that with an engine failure or other forced landing situation in aircraft of similar landing speed, at similar altitude, What is the compairative damage/fatality rate. Other data points although interesting seem to be somewhat trivial.

 

Until we change the laws of physics (as we know them) if we want a high performance, economical(?) aircraft, we must compromise by the higher landing speeds. If we are unwilling to compromise, by all means get/steal/build one with much lower landing speed and the increased safety that MAY be gained.

then why is the survivability in an ez been so much better then a LSA or a ultalight or C- 150 type

Evolultion Eze RG -a two place side by side-200 Knots on 200 HP. A&P / pilot for over 30 years

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then why is the survivability in an ez been so much better then a LSA or a ultalight or C- 150 type

Agreed, that is the topic of another monotribe. When I get time I will talk about that. As I said there are many factors which enter into the equation.

 

My point was not to say that the ultralites or C-150s are safer, as a matter of fact what is still in my head is the answer to that, however I must get away from the computer. It was only to say that when comparing accident/survivability, etc we must play on as level field as possible, which statistics don't.

I Canardly contain myself!

Rich :D

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k1234 wrote

 

It is unfortunate that you misinterpreted my attempt at humor :sad:

 

Statistics don't lie, but they don't tell the whole story. The P.I.C. of an experimental aircraft has a lot of freedom and a lot of responsibility. He(she)is totally responsible for safe operations. I don't think that anyone will argue that there aren't those out there that abuse those freedoms. Look through some of the NTSB reports and you will see that pilot error and mechanical failures are responsible for a large percentage of the accidents. Ask yourself if these accidents could have been prevented with better maintenance/design and prudent flight operations. It might be that the only thing as bad as a loose nut on the stick is a loose nut on the wrench.

Assumming the all pilots have the same amount of insanity, this equation that a friend gave me seems to still apply.

E = 1/2 m (V squared)

He says that kinetic energy equals one-half the mass times the velocity squared........so I guess that means that one should build a light airplane since energy is directly proportional to the weight and go extra slow since the energy is the square of the velocity. So I am going to start flying ultralights ! However, my Varieze is not too heavy (approx 700 lbs empty) and

sets down regularly below 70 mph. Guess I did something right. Now all I have to do is get my mental problems fixed.

WTJohnson

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<snip>E = 1/2 m (V squared)

He says that kinetic energy equals one-half the mass times the velocity squared........so I guess that means that one should build a light airplane since energy is directly proportional to the weight and go extra slow since the energy is the square of the velocity. So I am going to start flying ultralights ! However, my Varieze is not too heavy (approx 700 lbs empty) and

sets down regularly below 70 mph. <snip>

 

Because of the square term on velocity----small reductions in design landing speed (even with VGs) dramatically lower the landing kinetic energy (reducing 10 lbs only gets the KE down my 10 units-----reducing 10 kts gets the KE down by 100 units.

 

It is the KE that you must dissipate in a crash.

 

Another way to look at it (same airplane mass---only look at the V term)

30kt landing ultralite---KE~900

80kt landing EZ-------KE~6400

 

The EZ has to dissipate over 7 times the energy no matter where it lands. If it turns out to be a nice road with no powerlines, obstructions, and traffic, you will be able to dissipate all this energy into the brakes as heat. If you need to come to a sudden stop, that is a different matter.

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so I guess that means that one should build a light airplane

No, really it means you should build a light pilot. Small, light people are significantly more likely to survive car crashes (automobile wrecks) than obese 6'6" people.

 

What you would want out of your aircraft is for it to limit the maximum deacceleration in an accident to a level that your body can withstand. Cars (automobiles) do this by using a space-frame that crushes gradually, absorbing energy as it goes. But there are some small cars that will withstand ridiculous accidents and still keep the passenger compartment intact, but through failing to limit the deacceleration the occupants may still be killed.

 

To some extent adding weight to the aircraft will also increase the structure available to absorb it's energy, and assuming the pilot mass remains constant the ratio of sacrificeable mass to non-sacrificeable mass will increase. How effectively this happens is a matter of design. To use an extreme example, paraglider harnesses typically only weigh a few kilograms but provide relatively little protection for the pilot, in comparison with an aircraft airframe.

 

For any given design, lightening the aircraft will give you a lower stall speed which will give you a lower landing speed, which is obviously good. But as Drew pointed out lowering the landing speed, even by a little bit, is far more significant than lowering the mass by a similar proportion.

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No, really it means you should build a light pilot. Small, light people are significantly more likely to survive car crashes (automobile wrecks) than obese 6'6" people.

 

What you would want out of your aircraft is for it to limit the maximum deacceleration in an accident to a level that your body can withstand. Cars (automobiles) do this by using a space-frame that crushes gradually, absorbing energy as it goes. But there are some small cars that will withstand ridiculous accidents and still keep the passenger compartment intact, but through failing to limit the deacceleration the occupants may still be killed.

 

To some extent adding weight to the aircraft will also increase the structure available to absorb it's energy, and assuming the pilot mass remains constant the ratio of sacrificeable mass to non-sacrificeable mass will increase. How effectively this happens is a matter of design. To use an extreme example, paraglider harnesses typically only weigh a few kilograms but provide relatively little protection for the pilot, in comparison with an aircraft airframe.

 

For any given design, lightening the aircraft will give you a lower stall speed which will give you a lower landing speed, which is obviously good. But as Drew pointed out lowering the landing speed, even by a little bit, is far more significant than lowering the mass by a similar proportion.

But then again, it's not the kinetic energy that is the killer, it is the Delta V (rate of change in velocity from touching down speed until stopped) as well as the various things that can penetrate the cockpit, and perhaps our flailing about due to lack of restraints. Glass seems to have a great ability to make that delta V more lifestyle manageable than metals. ie smaller delta V. modern craft of the road persuasion have foam or liquid filled bumpers and crumple zones built into them so as to reduce the delta V as much as possible in the case of a collision. Perhaps this approach could make our, and other craft more survivable in the case of a less than successful landing.

I Canardly contain myself!

Rich :D

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But then again, it's not the kinetic energy that is the killer, it is the Delta V (rate of change in velocity from touching down speed until stopped) as well as the various things that can penetrate the cockpit, and perhaps our flailing about due to lack of restraints.

Actually---it is the KE---and it is the items that you pointed out. But lets freeze some variables to get a little bit of understanding. All airplanes have a landing speed that for the most part does not change (unless you have a configuration problem/damage, that necessitates excess speed). On EZs in particular, you can lower that speed somewhat by adding trailing edge fences.

 

Now pick your landing area (forrest, cornfield, grass, highway, etc) then speculate on performance of "absorbing" the KE with various aircraft (paraglider, parachute, ultralight, EZ, 747, etc).

 

Where your thinking really comes into play is that you are already flying a very specific airplane with a very specific landing speed. You are now engine out, and only have a limited set of options. Now those variables are set. No more time to talk about design landing speed. No more time to talk about crumple zones. Those were set when you built the plane. Now it is all about absorbing the KE as you pointed out.

 

-nice flat road--but lots of wires going across it that are hard to see (If I miss the wires, I can absorb all the KE in the brakes and still have an aircraft to fly. If I hit the wires, KE may be absorbed very quickly and I may not live or might lose my legs

 

-Forest off to the side of the road. KE absorbtion will be very fast and hurt/kill

 

-River next to the forest. No EZ pilot has ever died intentionally landing on the water but the aircraft is a total loss.

 

-grass field. Unless on a hardpack grass surface, most of these airplanes do not survive the landing. Pilot survivability is mixed

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But then again, it's not the kinetic energy that is the killer, it is the Delta V (rate of change in velocity from touching down speed until stopped) as well as the various things that can penetrate the cockpit, and perhaps our flailing about due to lack of restraints. Glass seems to have a great ability to make that delta V more lifestyle manageable than metals. ie smaller delta V. modern craft of the road persuasion have foam or liquid filled bumpers and crumple zones built into them so as to reduce the delta V as much as possible in the case of a collision. Perhaps this approach could make our, and other craft more survivable in the case of a less than successful landing.

Having a crash landing without hitting a solid wall seems to be rather obvious even without the physics. However, my friend that gave me the equation was my high school physics teacher long ago in 1955.

The best demo I ever had was seeing the results of a KR 1 crash at Corona, CA airport also long ago. The plane crashed along the south side of the runway apparentlly because of lack of gas to the engine. If I recall correctly there was some fuel in the tank, but it would not drain with the nose pointed up. Anyhow, this plane broke up into a thousand pieces of foam and wood which slowly absorbed the energy and the pilot walked away without a scratch.

It's not that I liked the KR's, since I thought that they were not structurally sound.......but it did have a benefit in turning itself into many pieces on impact as it cartwheeled.

WTJohnson

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Actually---it is the KE---and it is the items that you pointed out

force, mass, energy... KE versus acceleration are really two sides of the same coin, surely? If you double your speed then fly into a cliff*, you quadruple your deacceleration (delta V).

 

*to ensure a fixed distance of deacceleration.

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Rather than arguing at cross purposes with snippets of factual information, here are a couple of references:

 

ftp://ftp.rta.nato.int/PubFullText/RTO/EN/RTO-EN-HFM-113/EN-HFM-113-06.pdf

 

for information on human tolerance and crash survivability, with a lot of very useful information regarding what it means to crash, and:

 

http://www.airaffair.com/Library/Archive/Part1/emerg_landing_techniques

 

which is an earlier subset of:

 

http://www.docstoc.com/docs/832750/FAA-H-8083-3A-Airplane-Flying-Handbook----7-of-7-files

 

in which a lot of useful information about planning for crashes and how to absorb energy is presented.

 

Basically, restrain yourself well, hit soft things, go slowly, and decelerate horizontally rather than vertically (in a nutshell).

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Rather than arguing at cross purposes with snippets of factual information, here are a couple of references:

 

ftp://ftp.rta.nato.int/PubFullText/RTO/EN/RTO-EN-HFM-113/EN-HFM-113-06.pdf

 

for information on human tolerance and crash survivability, with a lot of very useful information regarding what it means to crash, and:

 

http://www.airaffair.com/Library/Archive/Part1/emerg_landing_techniques

 

which is an earlier subset of:

 

http://www.docstoc.com/docs/832750/FAA-H-8083-3A-Airplane-Flying-Handbook----7-of-7-files

 

Thanks for the references Marc. I quickly read thru all three and will have to try again after I recover. Guess I did figure after reading the above that crush zones and air bags would be good features. Guess the original KR design with foam wing ribs and little structural integrity had good crush zone qualities.

 

Another couple of practical points relating to Variezes and other canards: They do flip over and/or cartwheel in chest high hay and also in corn fields, so if you can find someplace other to land like on water (Hudson River ?) it may be advisable......with nose gear down.

WTJohnson

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Actually---it is the KE---and it is the items that you pointed out. .......

 

So lessee-- if it is the KE that causes the damage, while I am flying at touchdown speed, where the KE is identical, why don't I feel the need to count my limbs.

 

The KE only exhibits itself harmfully when there is the delta V where the KE is converted to crunched metal/glass and bent bones. With a slow delta v, such as in a normal landing, since it happens over a long period of time (relatively) we feel it as deceleration, faster the deceleration the more chance of injury.

 

Perhaps we are just talking about semantics :)

I Canardly contain myself!

Rich :D

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It is largely semantics. Acceleration is what does the damage, but in a crash situation the accelerations are likely to be approximately proportional to the kinetic energy. To see why this is true without doing the maths, consider car braking distances. Drivers should know that braking power is limited to a fixed deacceleration. If you double your speed your braking distance quadruples. To stop within the same distance, you have to quadruple your deacceleration also.

 

I can see an argument that if you're moving faster you're likely to have a longer distance to deaccelerate, provided you don't hit a cliff. For example, if you fire two bullets into water, a high velocity round will penetrate deeper. If you land and hit a hedge, perhaps you'll penetrate further through and the acceleration will not be quite proportional to the square of the velocity.

 

On the other hand, if you land with a high sink rate or nosedive into the ground, most of the deacceleration will be provided by the landing-gear and aircraft structure, rather than the ground. There's a fixed amount of structure, whatever the change in velocity.

 

It's also absolutely clear that if you have a given amount of kinetic energy and you reduce this to zero by stopping, all that energy has to go somewhere. Conservation of energy is a fundemental law of nature. Ideally it will all be dissipated by the airframe, hedge and by digging up earth or heating water during a water landing. In the worst possible scenario it all gets dissipated by mashing the pilot to a pulp, leaving the rest of the world intact. This isn't an entirely theoretical problem - early protective paragliding harnesses were rigid carbon fiber, and could survive just about any paragliding accident unscathed. They actually increased pilot injuries though.

 

Thanks for the references Mark. There's some interesting reading in there.

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