Rand Robinson KR-1 Crashable?

[Harley Dickinson]

Hello All, My name is Harley and I am 15 years old and i am interested in building a KR-1 From Plans anyone owned one?
I have heard they are not the best flying airplanes but they seem to be a pretty good bang for the buck.....
There have been 2 crashes at my local airport including one dumb*** performing a high speed taxi test with no wings, the airplane
thrown aloft and smashed into the ground inverted... I am taking lessons with a former Alaska Airlines/USAF pilot who has 28000
Hours and we are flying his RV-7..... so the point of me telling anyone listening that is so that they are aware that i have high performance
airplane expierience..... So anyone who wants to help me decide on an airplane, give me your ideas..... THANK YOU SOOOOOOOO MUCH
:D

[steveinindy]

Planes are generally only as safe as the pilot (or overconfident fool who thinks he's a pilot) behind the controls. That said, there are some aircraft that are better than others when it comes to crash survivability. I don't have any personal flying experience with the KR-1 so I really can't say for definite but it is definitely not one that appeals to me although it's mostly because I'm not a fan of the bubble canopy to be honest.

[Frank Giger]

Steve is hedging!

Without going into internal structure, let's define a "crash" as an off-airfield landing due to an engine out first.

Assuming positive control, the gross weight is 750 pounds and the stall speed is 52 mph, which means the momentum is fairly low, and barring some really bad luck should be pretty high on the surviveable scale. An NTSB search bears this out.

Next we'll look at the dreaded spin on base to final. Oof. It depends on how one strikes the ground, but the NTSB shows it related to a fatality on the search I did.

[tdm]

Steve is hedging!
Without going into internal structure, let's define a "crash" as an off-airfield landing due to an engine out first.


I like this definition. I also like 'crash' as; "a landing in which the vertical component of flight is reduced to zero in a small amount of time sufficient to cause structural fatigue."

[steveinindy]

Assuming positive control, the gross weight is 750 pounds and the stall speed is 52 mph, which means the momentum is fairly low, and barring some really bad luck should be pretty high on the surviveable scale. An NTSB search bears this out.

It's a very survivable event but the one big problem with the way that the NTSB categorizes injury is that someone who is permanently paralyzed from a spinal fracture, the person with a crippling head injury and the guy who breaks his ankle are all classified as "serious". For that reason, we really don't know the morbidity for these crashes. Looking at the mortality side of the statistics is fine but it gives an incomplete picture of the issue at hand.


Next we'll look at the dreaded spin on base to final. Oof. It depends on how one strikes the ground, but the NTSB shows it related to a fatality on the search I did.

Although given the low speeds involved, such events would be likely survivable in the face of restraints and structure design to withstand real world impacts not standards that were derived in the 1930s based off of assumptions on the tolerance of the human body to deceleration. For instance, some of the seat and restraint attachment requirements for g load are about one order of magnitude (that's a factor of ten for those on the forums who aren't fellow math geeks) below the bottom end of the limit that is generally as the "voluntary" threshold of human tolerance (meaning that someone (in this case, Dr. John Paul Stapp) was willing to allow themselves to be exposed to such levels). I'm not saying we could make all these crashes survivable but we could certainly lessen the frequency of death and lessen the severity of injury among people that would currently survive (for these types of crashes as well as the hard forced landing crashes, etc).

It would be one of the ways to prove that general aviation is safer: make it so. Experimental aviation is more than just an FAA category. If we're going to be building something, why not do it in a way that makes all aviation safer by being a proof of concept? We have the materials, we have the skill and most of us should have the drive- if not to protect ourselves then to protect our families who fly with us and to protect our friends. If you need another reason to look at this as a worthwhile project: many of you gripe about the FAA and NTSB "meddling" but if we take it upon ourselves to do things to minimize the things that get their attention (such as the body count and bad press involved with crashes that kill people), then they have less of a reason to force us to do things that we may not appreciate. Just a thought....

[martymayes]

.... so the point of me telling anyone listening that is so that they are aware that i have high performance
airplane expierience..... So anyone who wants to help me decide on an airplane, give me your ideas..... THANK YOU SOOOOOOOO MUCH
:D

Being experienced and proficient in high performance airplanes is not going to help much when you're flying a dynamically unstable airplane.

Lots of KR's have been built and flown so despite any shortcomings they represent a popular homebuilt from the past. No doubt the appeal is low cost. I've always thought it would be fun to build one so I say GO FOR IT! The experience would be priceless. I've always liked the idea of a KR2 with a single seat but that's just me.

[martymayes]

Assuming positive control, the gross weight is 750 pounds and the stall speed is 52 mph, which means the momentum is fairly low, and barring some really bad luck should be pretty high on the surviveable scale.

There use to be a YouTube video of a KR crashing during a high speed fly by. After the dust settled, the pilot was sitting upright in a pile of splinters, dazed but otherwise ok. Not vouching for the crashworthiness of a KR because I'm sure it was more luck than anything else. Survivability involves a lot of factors.

[martymayes]

I like this definition. I also like 'crash' as; "a landing in which the vertical component of flight is reduced to zero in a small amount of time sufficient to cause structural fatigue."

So hitting a structure while in flight would not be a 'crash'?

[rwanttaja]

Are you sure you didn't mean the KR-2 instead? The KR-1 is relatively rare; there are about 150 examples on the FAA registration database while there are nearly 600 KR-2s. The -2 is more popular since the -1 is a single-seater.

I've got a database of homebuilt accidents that covers 1998 through 2010, with the data extracted from the NTSB records. There was one KR-1 accident in that 13-year period, which I believe is more a reflection on the rarity of the type than any particular safety level.

For the KR-2s, the percentage of accidents due to pilot miscontrol is about the same as the rest of the homebuilt fleet. The KR-2 does have a higher rate of accidents due to fuel system problems... 12.5% vs. 3.5% for overall homebuilts.

Ron Wanttaja

[martymayes]

For the KR-2s, the percentage of accidents due to pilot miscontrol is about the same as the rest of the homebuilt fleet. The KR-2 does have a higher rate of accidents due to fuel system problems... 12.5% vs. 3.5% for overall homebuilts.


Any idea of the rate of gear up accidents? I thought all KR's with retract has had at least 1 gear up mishap.

[rwanttaja]

Any idea of the rate of gear up accidents? I thought all KR's with retract has had at least 1 gear up mishap.
No way to tell, from the NTSB database. Landing gear up, per se, is not a reportable event unless someone gets hurt or serious damage occurs. Egos don't count. :-)

A gear-up accident not meeting the criteria of NTSB 830 would be considered an "incident." The FAA does maintain a database of incidents, but I've never fiddled with it.

Ron Wanttaja

[tdm]

So hitting a structure while in flight would not be a 'crash'?

Perhaps that could be a 'collision', and 'crash' could be a subtype. According to Merriam-Webster, a crash as related to aviation, is "to damage (an airplane) in landing".

[Kyle Boatright]

Any idea of the rate of gear up accidents? I thought all KR's with retract has had at least 1 gear up mishap.

We had a fairly active KR community here in the 70's. Before my time, but when I first got into the EAA, the KR guys were pretty much winding down, but they did share a few stories. With that in mind, yes, most of 'em had a gear up at one time or another. Eventually, several of the retractables were converted to fixed gear, with minimal performance loss.

And for the OP: My belief is that the KR is a dated design. If I was looking for something light and sporty, Bruce King's BK-1 would be on my list. That, or the Thatcher CX-4. Here is a link that will take you to several VW powered designs:

http://www.greatplainsas.com/chooseaircrft.html

[dbcrn]

Just about all KR series aircraft recently built or being built have fixed gear. The original retract design was very short and not very sturdy, having folded up on several pilots upon landing.
I'm building a KR2S, which is the stretched version of the KR2. Mine is also stretched even further, which will contribute to stability. The KR2S is inexpensive to build and very durable. Being completely plans built, it is also easy to customize. Mine is going to be a few inches wider and be powered by a .060 Corvair 2700 engine.

[kr2flyer]

I'm a survivor of a KR-2 crash. Prop strikes on landing disabled us so that a climb proved difficult. Struck a 60 foot pine tree on go around and nosed into trees. The structure of the KR was intact all the way to the ground. Subsequent fire destroyed the entire aircraft after pilot & I had walked away from scene. Helo flight to trauma center was less fun than my first and only ride in a KR. Still building mine and hope to finish in another 20 years! Check out WWW.KRNET.org (http://www.KRNET.org) for lots of free info, advice and support. KR forum at AirVenture Oshkosh is a good place to meet and quiz pilot/builders. There is an annual gathering of KR's at Get all the info you can before buying the plans or the first piece of spruce.

Copied from the KRNET.ORG site: The "Official" 2012 KR Gathering will be held at Mt. Vernon, Illinois (MVN) (http://www.airnav.com/airport/kmvn), and will be hosted by airport manager Chris Collins, with help from various KRnetters including Larry Flesner, September 20th-21st. More details can be found at www.KRGathering.org (http://www.krgathering.org/) a few months before. Usually you can expect about 10-20 KRs to fly in for the Gathering, depending on the weather. 2007 was a record, with 21 flying KRs in attendence. 2012 will be even better, as even more KRs are flying for the first time, and more importantly, it'll be the 40th year of flying KRs! Our goal is to have 40 KRs fly in, so this could be an all time record, and the opportunity to see KRs that have never been seen at the Gathering before. This is THE place to put your hands on real KR aircraft so don't miss it! If you're light and lucky, you might just get a ride in one. You won't likely forget it soon either. The die-hards will arrive on Thursday, the 19th.

[steveinindy]

pilot & I had walked away from scene. Helo flight to trauma center was less fun than my first and only ride in a KR

Wow....talk about unnecessary use of aeromedical transport.

[Frank Giger]

He might have had an onset of STS (Sudden Tourette's Syndrome) where one begins to swear uncontrollably after having a wreck that sees the aircraft reduced to cinders and slag.

Glad to hear you were okay!

[Roger1]

Hello All, My name is Harley and I am 15 years old and i am interested in building a KR-1 From Plans anyone owned one?
I have heard they are not the best flying airplanes but they seem to be a pretty good bang for the buck.....
... I am taking lessons with a former Alaska Airlines/USAF pilot who has 28000
Hours and we are flying his RV-7..... so the point of me telling anyone listening that is so that they are aware that i have high performance airplane expierience.....

The KR does, theoretically (and perhaps too literally) give you a lot of "BANG" for your buck. That "bang" could be the sound of impact.

Compared to you, I have high-performance stick time in bigger/hotter stuff than an RV-7. But, though tempted, I'm not eager to fly a KR. Like the BD-5, it's a seductive little hot-rod that makes you think you can zoom away for pennies, joyously into the wild blue yonder, without a care. And, like the BD-5, several people have died in them.

While maybe one out of 20 or 30 or so sets of KR plans actually turns into a real flying plane, those 2,000 or more flown KRs have some blood in their history, according to the Aviation Safety Database of the Aviation Safety Network (a service of the Flight Safety Foundation), there have been:

KR-1 - 26 crashes (approx. 11 fatal), http://aviation-safety.net/wikibase/dblist.php?AcType=KR1&page=1
KR-2 - 111 crashes (approx. 57 fatal). http://aviation-safety.net/wikibase/dblist.php?AcType=KR2&page=1

But that's probably not the whole story. FSF data probably groups by manufacturer's name (in this case: "Rand Robinson"), but the FAA registration of homebuilts commonly uses (at least partly) the name of the builder in the "Manufacturer" name. This can result in official accident data not disclosing all the accidents associated with a type of homebuilt, at least not grouped under one readily identifiable name. Add in variations of the model name (e.g.: "KR-1" or "KR1" or "KR 1"), and you could get further scattering of the data.

The NTSB Aviation Database ( http://ntsb.gov/_layouts/ntsb.aviation/index.aspx ) reports:

KR-1 - 30 crashes (8 fatal) -
http://ntsb.gov/_layouts/ntsb.aviation/Results.aspx?queryId=a0d685c5-ef31-4287-b240-a0c42f54954f

KR-2 - 126 crashes (40 fatal) -
http://ntsb.gov/_layouts/ntsb.aviation/Results.aspx?queryId=90714b74-ca70-4c78-b7e6-33529bcc41f4

KR-2S - 4 crashes (1 fatal) -
http://ntsb.gov/_layouts/ntsb.aviation/Results.aspx?queryId=90714b74-ca70-4c78-b7e6-33529bcc41f4

Again, I doubt that's the whole story in the U.S., let alone abroad. But reading the accident reports could be very educational about KR issues.


SOME THINGS TO WATCH FOR on the KR PLANES:

Choose your engine as if your lifle depends on it; with the KR, it apparently does.

According to the FSF report on one of the KR-2 crashes, the builder had used a certified aircraft engine which was bigger than the Corvair engine that the designer had spin-tested the KR-2 with. The homebuilder decided to spin-test his own KR with the bigger engine (that the plans apparently said was OK). Not good. The plane never got out of the spin, and that was the end. The FSF report seems to suggest that the KR plans supplier / designer just shrugged it off, saying he hadn't spin-tested with that engine, only the smaller one.

Remember that the KR is a TINY airplane with short-coupled controls, and is reputedly twitchy in pitch response (longer body KR-2S adds 16" or so, possibly calming the twitch a bit). That's a common complaint about micro airplanes (like the BD-5). See KR enthusiast Mark Langford's "KR2S Opinions" at http://www.n56ml.com/kopinion.html

The stubby, pitch-twitchy KR may have a narrower safe CG range than the plans suggest. See KR enthusiast Mark Langford's "KR2S Opinions" at http://www.n56ml.com/kopinion.html

The KR puts you close to the ground (and its obstacles) with less time for you to respond to any problem while zooming along (or just above) the surface. And the KR offers little-to-nothing between you and the dirt to crush, absorb and soften impacts. (Compare that to a Cessna 150, or any fixed-gear, strut-winged Cessna, and you can see why Cessnas have top ratings for safety among gen. av. planes -- and the KR perhaps a bit less.)

CRASHES AREN'T PAINLESS:

Don't comfort yourself with the assumption that a crash will be instantly fatal, and thus painless. Crash fatalities in general aviation very often result from the impact-mangled victims burning to death, slowly. Some stats have suggested fatal fires kill about half of fatality victims.

And while about half of KR crashes are fatal, over 85% are "w/o" (write-offs, which is to say: "totaled"). In such crashes, when "survived," pilots (and passengers, if any) are commonly severely injured and/or burned, often with resulting severe and permanent disabilty and/or disfigurement.

A first-time project for an inexperienced young pilot probably would be more wisely chosen from among the tamer, more tested, safer planes out there. That, frankly, is true for everyone, but especially for those who have so much to lose, and so little experience dealing with the dangers of flight, and the passions of youth.

No plane is worth dying for.
You can't get any of the joy of flight in a coffin.
Fly safe, fly more.

[cub builder]

Much of what has been said about the KRs here is true. Unfortunately, Ken Rand died decades ago, so on paper, the the plane never evolved. However, in the builder community, the plane has indeed evolved into a better performing safer aircraft. The allure of the KR series of aircraft is the low cost and pay as you go build it all from scratch. Thus, many of the KR builders are trying to scrimp and save pennies. That was my situation 20 years ago when I built one. At this point in time, I have nearly 1100 hours on my KR with nearly 20 hours in the last 2 weeks, and can truthfully say it is one of the most enjoyable planes I have ever flown. I fall in love with it all over again with every flight. I should also note that over the years I have made substantial modifications to the plane to improve it's handling and performance.

The KR-1 and KR-2 were both dynamically unstable in pitch with an extremely light elevator that often times lead to over-controlling on the first flight. If you really want to build a single seat KR, build a -2S, then narrow the fuselage down to whatever width you desire. Join the builders forum KRNET.org and by all means check out Mark Langford's and many other builders web sites linked from krnet.org. There are a lot of significant improvements documented on these web sites that make for a much safer aircraft. The most significant that is in the plans is a larger tail and longer fuselage of the -2S. That makes a significant contribution to stability. On the web sites, you will also find other improvements. Fixed gear is almost a must as it is lighter and more durable than the original retracts, and properly faired, is less drag. That's a winner all the way around. There are plans for a different wing that is cleaner than the original wing design. There are plans for a different tail that has a real airfoil to it and should be built to be significantly larger than the -2S plans tail, which really tames the aircraft. There are plans for flaps and/or belly board for deployable drag, which makes the aircraft significantly easier to land. You will see KR aircraft sporting all kinds of engines, VW, Corvair, Jabiru (both 2200 and 3300), Continentals, Lycomings, and nearly anything else you can name. I'm not a big fan of auto engines in these aircraft as the number of forced landings with them seems to be higher than acceptable to me, but many are flying them reliably.

As for the crashability of the aircraft, many are badly damaged and written off following a crash. However, the wooden structure does a good job of absorbing impact forces while the airframe breaks apart. I personally have not tried that yet, but have seen the after results of a few. :D

Also, don't be drawn in by the advertising. There are KRs that will go 180 mph (mine is one of them, but that's not cruise), and not on a VW engine. There are some that can get off short and land short, but those are very light and not long distance cruisers. There are some with long cruise range, but they aren't going 180 mph either.

As designed, it's not a great aircraft. But with the help of the builder community, it can be built to be a nice flying, fast and sporty, inexpensive aircraft.

-Cub Builder

[Bob Dingley]

Good work Roger1. I lost a friend in his Miller Rand Robinson KR-2. He installed a Solar T-62 turbine of about 120 HP. It was pretty hot and he had less than 100 hrs. It was over quickly. See NTSB DFW 05LA129, event date 5/21/2005.

I looked it over in his shop prior to the accident and thought (to myself) that it was highly unlikely that I would ever strap into a KR-2 especially a T-62 powered one I am not a low time pilot and have lots of turbine time. The ship had just been converted from conventional gear to tri-gear. He had lots experienced mentoring during the months prior to the flight. So sad.

Bob

[cub builder]

That is an unfortunate accident, and I hate to see anyone perish in an aircraft. But gosh, the accident report reads like he thought he was invincible. Really? 55 hrs total pilot flight time spread over 30 years, then jump into a squirrelly handling amateur built aircraft with a virtually untested turboprop powerplant. Really? Do we see an accident chain building here? There is much that can be done to the aircraft to tame it down and make it a fast, sporty, and safe aircraft. I doubt any of those mods had been applied. The addition of the turbine would not be among those mods recommended to improve the aircraft. I am sorry about the loss of your friend, but I don't think you can blame the aircraft design for that.

Unfortunately, many KR accidents read like this one. Pilot has virtually no experience. Scrimped pennies to build an aircraft. Many that saw it thought it was substandard. Alternate engine was used to save pennies. Pilot crashes on it's first flight. Rarely is the airframe itself at fault. Often times it's the engine, but the handling characteristics of the plane in it's stock form is a definite contributor when the stall/spin/loss of control following the engine failure or partial failure happens. The user group has done a lot to address those characteristics. Unfortunately, those modifications are not included in the plans, so joining the user group is an absolute must for anyone interested in building a KR.

-Cub Builder

[Frank Giger]

So hitting a structure while in flight would not be a 'crash'?

Let's address this, because it's germane to the question of whether or not an airframe is more or less surviveable in a crash based on design.

No aircraft is designed to be surviveable in the infamous spin-on-base-to-final with a nose down impact, nor with a head-on collision with an object such as a tree or building, or any katywhompus crash (inverted, one wing down, etc.). Loads is done to minimize the effects of things like that, but at the end of the day weight restrictions throw out roll cages and airbags.

So in order to differentiate, we need a baseline "crash" that should be surviveable - the engine out landing on an unimproved surface. This was the criteria I used in selecting my own aircraft to build. In the case of tube-and-gusset Nieuport 11's, no fatalities or injuries above some scratches and bruises came from them - though they wind up turning turtle 90% of the time.

The one fatality in type was a power on nose dive from 400 feet into pavement - not something that one would fault with the design.

Now, then, if the KR-1 had a nasty habit of immediately catching fire or having bits of the airplane jump off and impale the juicy bits inside in those conditions it would be a red flag, or if the seats collapsed oddly and resulted in spinal injuries it would speak volumes.

[Floatsflyer]

[QUOTE=Frank Giger; No aircraft is designed to be surviveable in the infamous spin-on-base-to-final with a nose down impact, nor with a head-on collision with an object such as a tree or building, or any katywhompus crash (inverted, one wing down, etc.). Loads is done to minimize the effects of things like that, but at the end of the day weight restrictions throw out roll cages and airbags.[/QUOTE]

Not at all. I don't personally know about roll cages but I can vouch for airbags because I have them--on all 4 seats. They're called Amsafe and they've been certificated for certified GA since 2003. They come as standard equipment on most if not all new familiar OEM brands. They are now on literally thousands of GA type aircraft including STC's for retrofits on aircraft prior to 2003. Don't know if systems are available for E-AB but I'd be surprised if they weren't.

The airbags are built into the lap portion of a shoulder/ lap belt inertia reel system.They're comfortable, weight almost nothing(don't even know it's there)and they give me a sense of positive security. Weather or not it saves my life or prevents serious injury, it's good to know it just might.

[Frank Giger]

I had forgotten about the in-the-strap airbags...but in cockpit airbags (built into the panel or on the airframe itself are still out). How much do they weigh? You mentioned they don't feel heavy to the pilot or passenger, but from a builder's point of view that isn't the right weight to take into account!

Floats, you'll remember that I'm on the very light end of aircraft, and it skews my perception. Very light as in I left off the ELT on my bird due to weight!

[1600vw]

The other day when out and about I drove past an airfield that is used by a Crop duster. Its the turbine powered units. As I drove by there sat the crop duster in a ball. The wings where smashed in to the fuselage that you could not make out that they where indeed wings. The engine was on the ground and the nose smashed in. The tail was gone. Nothing left of the tail Nothing. But the cockpit was intact.

A buddy of mine did an NTSB search and found out what happened. The pilot reported he had made about nine flights that day. On this last flight he fueled and filled the airplane with whatever he was spraying. He gets 3/4 of the way down the field and she was not coming off the ground. He starts dumping everything. He gets her in the air right above the corn and still dumping. He comes to a tree line and had to bank and turn. He spun her in. He was bruised but not hurt. The only thing you could make of that airplane was the cockpit and that is about it. You could read the N number but it was a wrinkled mess.

This happened one month ago.

Tony

[Floatsflyer]

I had forgotten about the in-the-strap airbags...but in cockpit airbags (built into the panel or on the airframe itself are still out). How much do they weigh? You mentioned they don't feel heavy to the pilot or passenger, but from a builder's point of view that isn't the right weight to take into account!

Floats, you'll remember that I'm on the very light end of aircraft, and it skews my perception. Very light as in I left off the ELT on my bird due to weight!

Frank, I've looked on-line, mr. Google and in my POH and I can't find the weight for the system other than the words "lightweight". I'm a member of the Cessna Pilots Association, I'll contact the tech team there, they know everything. If I get the number I'll post it here.

One other thing, I thought ELT's were mandatory, maybe not so in E-AB's??

[Frank Giger]

ELT's are required in all aircraft that can carry a passenger.

Mine is single seat, therefore not required. Shows who the FAA really cares about in aircraft!

[rwanttaja]

ELT's are required in all aircraft that can carry a passenger.

Mine is single seat, therefore not required.
14CFR 91.207(f)(9), to be exact.

And, actually, to gently correct Frank, the exclusion is "Aircraft equipped to carry not more than one person." Doesn't matter if that second seat holds required crew or a passenger.

Ron Wanttaja

[Frank Giger]

14CFR 91.207(f)(9), to be exact.

And, actually, to gently correct Frank, the exclusion is "Aircraft equipped to carry not more than one person." Doesn't matter if that second seat holds required crew or a passenger.

Ron Wanttaja

No matter what their role, I refer to anyone in the right or backseat of an aircraft I'm in as hostages.

[rwanttaja]

No matter what their role, I refer to anyone in the right or backseat of an aircraft I'm in as hostages.
When I die, I want to go quietly in my sleep like my Grandfather...not screaming in terror like his passengers. :-)

Ron Wanttaja

[rwanttaja]

No matter what their role, I refer to anyone in the right or backseat of an aircraft I'm in as hostages.
I've been flying a single-seat aircraft almost exclusively for the past twenty years (and for a time before that). Occasionally, on Unicom, I'll refer to a Cessna 172 as a "Crowd Killer" or a "Cessna Heavy".....

Ron Wanttaja

[1600vw]

I've been flying a single-seat aircraft almost exclusively for the past twenty years (and for a time before that). Occasionally, on Unicom, I'll refer to a Cessna 172 as a "Crowd Killer" or a "Cessna Heavy".....

Ron Wanttaja

That is funny right there. I have to remember this and use it...Ron you crack me up.....lol

[Floatsflyer]

Frank, I've looked on-line, mr. Google and in my POH and I can't find the weight for the system other than the words "lightweight". I'm a member of the Cessna Pilots Association, I'll contact the tech team there, they know everything. If I get the number I'll post it here.

Frank, I got the number directly from the horses mouth. The national sales manager for AmSafe wrote to me in an email: "We use a ball park figure of 1.5 pounds per seat" and sent me relevant weight and balance AmSafe/Cessna documentation.