What Price A Masterpiece? By Dick VanGrunsven

For those without FaceBook: http://www.facebook.com/notes/vans-aircraft-inc/what-price-a-masterpiece-by-dick-vangrunsven/237594966250883

In June, an article entitled* ?Mod Masterpiece,? appeared in Sport Aviation.* It extolled many features of the absolutely gorgeous interior that Greg Hale built into his award-winning RV-10. Unfortunately (perhaps unwittingly) the article drew our attention more to the price he paid than his admittedly wonderful workmanship and customization. No, I?m not referring to the usual costs measured in dollars and building time.* I?m referring to the price that airplane builders often pay in reduced utility and, more important, in impaired safety.*

*
The article started with a pull-quote: ?The RV-10 impressed us since you could load four passengers and bags and be well within the maximum gross weight and CG.?** Normally, that?s true. An RV-10 usually weighs about 1600 lbs empty, so with its rated 2700 lb gross it has an 1100 lb useful load.* That translates into four 170 lb people, sixty gallons of fuel, and sixty pounds of baggage. But given what article goes on to describe, this quote appears increasingly ironic.
* *

Mr. Hale?s modifications and additions had a dramatic effect on the empty weight of his RV-10.* The reported empty weight of 1848 lbs -- 248 lbs over the 1600 lbs that we?d consider ?standard.?* This translates into the equivalent of 1? passengers who must be left behind or 41 gallons of fuel, which must remain on the ground if the airplane is to remain within the design gross weight limit of 2700 lbs.* With full standard fuel tanks, his RV-10 effectively becomes a 2-seat airplane. Then, we noticed the spec sheet accompanying the article giving the fuel capacity as 120 gallons!* If this is accurate, it means that, in addition to the cabin interior modifications, Mr. Hale apparently installed additional fuel tanks in his RV-10 and doubled the standard sixty gallons.* With 120 gallons on board, his RV-10?s payload would be further reduced to a 132 lbs -- not even a single-seater anymore.

*
Here?s another, perhaps more appropriate, quote: ?You can?t have your cake and eat it too.?
*
Continued...

Many builders will tell you that it is not possible to meet the factory empty weight figures.* In some instances this may be true ? some kit suppliers have been known to optimistically quote an empty weight based on an unfinished and unequipped prototype, or weights that could never be equaled by subsequent builders.* But the 1600 lb. empty weight Van?s Aircraft quotes for a 260 HP Lycoming-powered RV-10 is realistic.*** An example is my personal RV-10, built from a standard kit and employing no special weight saving efforts.* It weighs, empty, just 1595 lbs.* This includes full paint, wheel fairings, EFIS instrumentation, radio, transponder, GPS, 2-axis autopilot, ELT, an intercom system w/CD, carpeting and headliner, and landing lights.* Though it may seem spartan to some, it is comfortable and totally functional for long-distance VFR flight, day or night.*

* **
From long experience we anticipate that builders will customize, and will add weight in the process.* This does not mean that there are not compromises or penalties involved.* At the very least, any added weight will subtract from the useful load of the airplane.* This is the reason that so many 4-seat factory airplanes cannot fly with full seats and full fuel at the same time.* But for homebuilt aircraft, this is a compromise any builder has the freedom to make, and many do. But adding 248 lbs of* ?stuff? in the example above is rather extreme.* It is the equivalent of adding the weight of an entire ultra-light, engine and all.* It?s almost equivalent to adding another pair of RV-10 wings.*
* *

The spec sheet also notes Mr. Hale?s airplane has a listed gross weight of 2800 lbs instead of the 2700 lbs the factory specifies.* Yes, we realize that a builder of an Experimental Amateur-Built airplane can list any gross weight or flight limits he wishes.* It?s just that we don?t accept that.* Our factory specified gross weight is based on the best science we have available.* This includes careful stress analysis calculations and extensive static load and flight limit testing.* By way of contrast, we wonder what basis Mr. Hale (or any other builder who uses a higher-than-recommended gross weight) uses for establishing the 2800 lb gross weight of his airplane?* If it isn?t based on the same science and testing, we simply cannot recognize it as valid, and neither should anyone else.** Any ?penciled in? gross weight increase is just wishful thinking.* The laws of physics are not repealed by wishful thinking.

Continued...

*
But this discussion of payload trade-offs is not the primary purpose of this paper.* While we hate to see our laboriously designed 4-seat payload erode to a 2 1/2 seat limit, that is the builder?s privilege.* Our primary purpose here is to point out several modifications made to primary flight control systems and safety features.* We feel these are detrimental to safety, and that readers and other RV-10 builders should be aware of our concerns.** Modifications undertaken for otherwise good reasons can have negative consequences.
*
Specifically, we see a real problem with the front seat shoulder harness attach modification.* As designed the RV-10 uses a two-strap shoulder harness attached to a hard point in the structural cabin top. We used the two-strap (one over each shoulder) harness because it is the universal aircraft standard and has been demonstrated to be superior to the automotive style single cross strap.* Anchoring the harness to a hard point in the cabin top provides a near ideal load path for crash restraint forces. (See illustration 1.)
*
The subject airplane uses a single cross shoulder harness anchored to a hard point in the fuselage under and aft of the seat.* The strength of the anchor point is somewhat irrelevant in this installation, because the load path (see illustration #2) essentially applies the crash loads to the top of the seat back.* The low anchor point for the shoulder harness causes the tension in the strap to bear down on the occupant?s spine, and to pull forward on the top of the seat back.* The back of the Oregon Aero seat supplied in the RV-10 kit was not designed to withstand shoulder harness crash impact acceleration forces.* When the seat back fails, the upper body will pitch forward because the shoulder harness essentially becomes slack.** While some automotive seats do apply the shoulder harness loads to the top of the seat backs, we assume that those heavy automotive seats have been adequately designed and tested for this purpose.* The RV-10 seats have been designed and tested by Oregon Aero, Inc.* to withstand anticipated crash impact loads of the occupant, but not acceleration loads transmitted through shoulder harnesses.


Continued...

*
Another safety feature of the Oregon Aero seats is the foam used to make the cushions.* Its type, density, and lamination schedule have been carefully tailored and tested to absorb vertical impact loads.* Any changes or replacements may not provide equivalent protection.
*
In addition, the modification made to the active seat belt attach points is suspect.* Our design provides for each belt attached directly to anchor points in the airframe structure.* Anticipated crash acceleration loads are transferred in linear tension into these hard points.** In the subject airplane, the seat belts are attached to a small diameter cross shaft between the intended structural hard points. (See photo 1)* Crash acceleration loads will be applied normal to this cross shaft, loading it in bending, which in turn will apply eccentric (twisting) loads to the mounting brackets in the cabin structure.
*
The rear seat shoulder harness modification of the subject airplane also uses a single cross-strap rather than the standard RV-10 dual-strap harness.** The load path into the airframe is again an unknown ? in contrast to the static load testing performed on the factory supplied harness assemblies.* These transmit loads linearly to the aft fuselage structure.
Another worrying modification altered the attachment of the rudder cables to the rudder pedals.* Mr. Hale used an offset stud (see photo 2) on the rudder pedal to which the rudder cable is attached.* While this may provide a more attractive cabin appearance, it causes an inferior load path for the rudder control forces.* Cable tension loads will apply a twisting force to the rudder pedal attach horn.
*
While we?re on the subject of modifications and how they might affect safety, let?s go back to that question of sixty extra gallons of fuel. There is a cute saying in aviation that ?the only time you have too much fuel is when your airplane is on fire?.* Unfortunately, this is not entirely accurate.* The most obvious exception comes when the fuel load causes an over gross weight condition that adversely affects performance and flight safety.* Even if the additional fuel weight is within gross weight and C.G. limits, the location of the added weight can adversely affect the aircraft?s polar moment of inertia.* Reduced to its most understandable form, it means that the spin recovery characteristics of the aircraft will be affected.* While the article never says where the extra fuel goes in this RV-10, the most likely place for additional fuel tanks would be in the outer sections of the wing?outboard of the standard wing root leading edge tanks.* With regard to the polar moment of inertia, this is possibly the worst place (other than in the tail) to add weight to an airplane.* Also, weight added anywhere in the wing will affect the flutter characteristics of the wing.* The RV-10 wing has been subjected to Ground Vibration Testing (GVT) with standard tanks both full and empty.* With significant weight of any kind, structural or otherwise, added to the wing, the flutter speed limits will change ? and until the new arrangement is tested, nobody knows what the new limits will be.
*

Like many kitplane suppliers, we endeavor to supply very complete, thoroughly designed and tested airframe kits.* It is our hope that builders will construct the airframe assemblies in compliance our proven design.* Most do.* Details such as instrumentation, avionics, and cabin interior appointment are often not included in kits because we know from experience that builders have very special individual preferences for these details.* These are areas where builders can usually express their individuality without as much concern for safety of flight as would be the case with changes to the structure or aerodynamics.* I say usually because even any seemingly insignificant part of an aircraft can affect safety of flight.* With reasonable care interior appointments will remain benign.


*
We all know that builders of Experimental Amateur-Built aircraft have the right to make changes to their aircraft at will ? whether or not their changes are based on good science.* If they choose to operate the aircraft with a lesser or unknown margin of safety, that is their prerogative.* However, unless the aircraft is single-seat, any passengers carried in that aircraft will be exposed to the same unknowns that the pilot has accepted for himself.* We feel that this is a responsibility often overlooked by pilots.* While they may be willing to accept certain risks for themselves, what should their responsibility be to their spouses, friends, children, and grandchildren?**
*
Continued...

SIDEBAR:* WHO OWNS THE MARGIN?

*


It seems common practice among homebuilders to second-guess the factory engineers, particularly regarding gross weight increases.* Because of all of the “I gotta have” added features, empty weight creep erodes the aircraft’s useful load.** The simple solution for the homebuilder is to “pencil in” a new gross weight limit.* It’s only 100 lbs. (3.7%) more; how much effect can that possibly have?”* Imagine this example: you are on a mid-size airliner with a gross weight of 270,000 lbs.* Just before leaving the gate, the captain comes on the PA system and says: “we’ve overbooked more than usual today, so we’re going to assume that the factory engineers over-designed this airplane and allowed an abundant safety margin. We’re going to take off at 280,000 lbs. instead.** So move over, there are 50 more passengers coming on board.”* Run the numbers; it’s the same over-weight ratio as simply pencilling in an additional 100 lbs to the gross weight of an RV-10.

*

Along with gross weight increases, some builders take the same liberties with horsepower increases and speed increases, betting their lives on the assumption that the airplane is designed with a huge margin of safety---it is really far stronger than in needs to be.* This is not really true.* Certificated aircraft, and well-designed kit aircraft, are designed to withstand limit loads at specified maximum weights.*** During testing, they are subjected to ultimate loads, which are higher than design limit loads by a specified margin.* Yes, there is a margin between the design and ultimate strengths.** But that margin belongs to the engineer.* He owns the margin.* It is his insurance against the things he doesn’t know or can’t plan for, and the pilot’s insurance against human error, material variations, and the ravages of time.* Wise pilots respect this design safety philosophy and leave this insurance policy in effect by operating strictly within established limits.* They don’t try to steal the margin from the designers.

The end.

Note: see link for figures. Disregard. Thanks Phillip.

Pictures for the lazy:
Figure 1:

Figure 2:

Photo 1:

Photo 2:


I must admit, that seat belt bracket made me cringe.

Thanks

Jim, thanks for posting this, as I am one of those who do not have facebook.

I am glad to see some of the concerns I had are echoed by Van.

The plane is truly gorgeous, and Greg did a fantastic job with it, but like the title says-----"What price a masterpiece"

I gave it a "Like"

That there was a good article.

Thanks

Very well put. I hope that all builders take heed. Some builders are engineers, but that doesn't make them the designers. When it comes to never exceed speeds and gross weight, I personally hope and pray that everyone respects those limits. They truly are limits that can and will save your life and the life of your loved ones.

bird

Mike S said:

Jim, thanks for posting this, as I am one of those who do not have facebook.

Click to expand...

You don't have to sign up. Just go to Van's website and click on Facebook from the main page.

L.Adamson --- RV6A

I didn't read the article in sport aviation, but I did look at the pictures and was blown away. My wife saw it and called it Lexus plane. I gotta say after reading Van's reaction that I feel kinda let down. That shoulder harness route looks completely ridiculous and irresponsible. Sorry, but it's true.

I hate to see this- one builder being singled out in the most embarrassing way possible. *The concerns are valid, yes, but the approach is woeful. *I was sure hoping for that last paragraph with the happy ending...

ProfessorSpeed said:

I hate to see this- one builder being singled out in the most embarrassing way possible. *The concerns are valid, yes, but the approach is woeful. *I was sure hoping for that last paragraph with the happy ending...

Click to expand...

I gotta agree with you I love my RV-8 but have never been a big fan of the mother ship


P.s I have respect for them just not had positive interactions with them

ProfessorSpeed said:

I hate to see this- one builder being singled out in the most embarrassing way possible. *The concerns are valid, yes, but the approach is woeful. *I was sure hoping for that last paragraph with the happy ending...

Click to expand...

I'm pretty sure that "Sport Aviation" doesn't make you be the focus of a feature article. It is entirely voluntary.

RV10/Van

I must agree, although some very good points, this was a very poor way to handle the concerns. I do not know Greg however I once saw his 8 at an air show, the most beautiful 8 I have ever seen just like the 10. I think Greg represents what this hobby is about, yes there are a few safety issues like the seat belt however the rest is just a bad editorial. This guy may want to do long cross countries by himself and has simply added fuel capacity for that mission. If he wants to carry more passengers he can adjust his fuel load. I think Van is a great guy but this could have been addressed much more professionally.

Pat

Professionally said:

I hate to see this- one builder being singled out in the most embarrassing way possible. *The concerns are valid, yes, but the approach is woeful. *I was sure hoping for that last paragraph with the happy ending...

Click to expand...

Great article. However, in regards to the seat belts, I think I would end up with a compressed spine/broken back in a significant crash (among other injuries).

Seems to me that the stock design (which I did NOT modify) will create significant downward force in crash for someone tall like myself (6'3"). Am I wrong about that? (not an engineer, just an A&P)

I think that articles like the one Van wrote provide the community with a great perspective and an important counterweight to articles like Sport Aviation publishes. I really appreciate reading his stuff, and I sure didn't see any hint of anything I would label unprofessional. Van, keep the good articles coming.

Seatbelts...turbulence, acro, crash...

several reasons for a good restraint system... turbulence, acro, crashing... lots of turbulence and acro... crashing, not so much. The five point harness in my 7 is a good compromise.

Is there a 5th point option on the 10? It looks like he might have been attempting to get better turbulence restraint.

While talking about seatbelts, I thought it was pretty weird that I ordered an entire airplane kit (RV8) and did not receive any type of seatbelts. I guess I have to buy them separately. Who would of guessed...

He asked to be judged

n5lp said:

I'm pretty sure that "Sport Aviation" doesn't make you be the focus of a feature article. It is entirely voluntary.

Click to expand...

Perhaps even more relevant is that the builder submitted his plane for judging. It is entirely appropriate to judge the plane/build.

This situation is a great example of a set of flawed judging standard, IMHO. Give me safety and function over looks. Beautiful plane but I wouldn't want to own or fly in it.

Thanks, Van.

ProfessorSpeed said:

I hate to see this- one builder being singled out in the most embarrassing way possible. *The concerns are valid, yes, but the approach is woeful. *I was sure hoping for that last paragraph with the happy ending...

Click to expand...

You've got to be kidding me! Woeful!
Some people just don't get it.

jthocker said:

You've got to be kidding me! Woeful!
Some people just don't get it.

Click to expand...

I don't like the seat belt setup, the rudder pedal links have problem potential.........

But on the other hand..............Jon Johanson's "round the world RV4"

from the (Van's) website:

Even though Jon lost 22 pounds while preparing the airplane, it was soon apparent that, with enough fuel to make ocean-spanning legs, survival gear, communication gear and supplies, the gross weight was going to be higher than the recommended 1500 pounds. In the US, where the gross weight of an airplane in the Experimental category is determined by the builder, this would have been no problem. In Australia, it required an approval from the designer. When Jon contacted Dick VanGrunsven, Van was initially tempted to dismiss him as another dreamer.

"There are always a few people who just don't seem to grasp the fundamentals of what makes airplanes fly or perform." Van says. "They want to modify them in completely impractical ways. After I talked with Jon for a while, I realized that he did understand his airplane and his questions were good ones. When I visited Australia, I got a chance to meet him and I was impressed. If anyone was going to do what Jon was proposing to do, he was the one." After reviewing Jon?s modifications and qualifications, Van felt comfortable issuing a one time approval for a take-off weight equaling 136% of the recommended gross.

L.Adamson

Van's was presented with an undesirable situation. A beautiful, but practically flawed aircraft being presented in a "best of breed" type format.

I'm sure they didn't want to point at a customer, but even moreso, they wanted to hilight the compromises made in that aircraft, particularly the ones that aren't obvious to less techical individuals. They didn't want "everyman" to make the same modifications without a full understanding of the potential consequences.

2 Cents

The same article could have been written successfully without hanging Greg out to dry...let alone by the guy who made a profit off of his build. Dick doesn't work for the government...he is a businessman who should be concentrating on customer service as well as a quality product. He has announced at Greg's expense that he is the only one allowed to experiment with aviation. Had anyone else written this article naming names, the supermoderators would have shut it down in a heartbeat. I thought it was embarrassing to read. If Greg wants to fly his plane solo and naked, then he is entitled by law to do so. Now if you want to see a short-lived post...lol...watch this one...poof!

Peterk said:

The same article could have been written successfully without hanging Greg out to dry...

Click to expand...

How? (And I'm not intentionally being argumentative - I'd really like to hear your opinion on "how").

Seriously, Sport Aviation wrote a feature on a nice RV-10, pumping up all of the great things the builder did. And he did - beautiful airplane.

But Van can't have everyone out there trying to emulate that airplane, particularly a few of the particularly bad choices that were made but were presented in a positive light by Sport Aviation. Ignore the article and pretty soon there would be a bunch of -10's with improper seatbelt geometry and hardpoints, bad rudder cable linkages, etc.

So back to my question - how could Van's have pointed out the flaws in that airplane, which was featured in SA, without "outing" the builder?

Greg is a professional pilot, an engineer, and as you can see, eccentric. It's his plane to do what he wishes, if Van's wants to start flaming their customers it could get ugly.

Where is his haste with the planes I see on the ramp at airports and airshows? RV's that were thrown together with zip ties and terrible workmanship? They're out there. I've seen some that make me shake my head and go "wow."

If they want to control what becomes of their kits, they need to start building production aircraft.


BTW, the interior looks like a Lexus because that's what he was going for. Carbon copy.

Peterk said:

The same article could have been written successfully without hanging Greg out to dry...let alone by the guy who made a profit off of his build. Dick doesn't work for the government...he is a businessman who should be concentrating on customer service as well as a quality product. He has announced at Greg's expense that he is the only one allowed to experiment with aviation. Had anyone else written this article naming names, the supermoderators would have shut it down in a heartbeat. I thought it was embarrassing to read. If Greg wants to fly his plane solo and naked, then he is entitled by law to do so. Now if you want to see a short-lived post...lol...watch this one...poof!

Click to expand...

While I find your attitude, and backhanded challenge to those of us who are moderators, more than a little offensive, and IMHO childish, I will let your post stand, as there is something here I think needs to be addressed.

Your comment ".let alone by the guy who made a profit off of his build. Dick doesn't work for the government...he is a businessman who should be concentrating on customer service as well as a quality product. seems to me, at least to be quite shortsighted on the issue.

Yes, Van is a businessman. I see this article as being proactive in protecting that business, and those customers past, present, and future who might look at Gregs plane and decide if he did it, well, I am going to do so also---and not only that, but I will add X, Y, and Z too.

I do not know Greg, nor do I know his background or aeronautical savvy. For all I know, he is a PHD in aero design??

But, Van MUST speak out when he sees something that he, as the designer, considers problematic. To not do so would be to give tacit approval for the modifications------and in this crazy lawsuit happy society that equals Van accepting the liability for those changes.

I submit to you that by speaking out, Van is (in your own words) "concentrating on customer service as well as a quality product"

I for one, look forward to getting to see Gregs plane at Osh, and I also wish him a long and happy relationship with the plane.

Kyle Boatright said:

So back to my question - how could Van's have pointed out the flaws in that airplane, which was featured in SA, without "outing" the builder?

Click to expand...

A more tactful approach would have been a discussion on builder modifications in general; even using an example or two from Greg's airplane as appropriate. If someone were to write an airplane review here like Van did, it would be deleted by a moderator for being darn near a personal attack on an individual.

As someone who puts my own thoughts and experience out there for all to read in numerous places (including print magazines), I have to say that once you put it out there in public, you are open to public comment and criticism. There is no way that you can put the Genie back in the bottle - now, if you have put the information out there willingly, should you want to try.

Van has as much right to express his thoughts, knowledge, and opinions publicly as anyone else does - and no obligation to keep those thoughts private when the original information on which he is commenting is public in the first place. Polite disagreement, based on facts, does not meet my own definition of "flaming" someone. "flaming", by my definition is dealing with others in a disrespectful way - not just disagreeing with their position. I frequently disagree with what I see posted here n VAF, yet I don't remove it, so long as it is posted in a civil manner. that's my personal definition of Moderation.

Many of us make modifications to our Van's kits. Many of us posts about those modifications, and in so doing, open ourselves up to criticism (criticism can be both positive and negative by the way). Most modifications that gain you something in one part of the envelope takes something away in another - that is a sign of how well van has already balanced the compromises inherent in aircraft design. AS long as a person understands the limitations that he imposes with a particular modification, I have no issue with it. What concerns us all is that others might not appreciate those limitations should they try and imitate the results.

Paul

Flyfalcons said:

If someone were to write an airplane review here like Van did, it would be deleted by a moderator for being darn near a personal attack on an individual.

Click to expand...

Not sure why you would think that. I have seen much more pointed appraisals of other aircraft in the six years I have been a moderator here, and they haven't been deleted. As long as there isn't any name calling, or personal attacks; the critism is fact-based, and the tone is civil, what's to delete?

I am amazed at the skill of some builders. But that being said, the empty weight is an embarrassment. The airplane like so many Americans is obese.

No doubt Mr. Hale could build an RV-10 that would come in at 1600 pounds and blow everyone away. That would be impressive.

I suppose some prefer the expensive auto look, others a simple old pick up will do. But when it comes to an airplane, performance is what counts and obese airplanes, like obese humans, are not going to win the race. It may be pretty, but it will be last.

As the designer, Van would be remiss in not pointing out the aerodynamic and safety compromises of this particular RV-10. He really has no choice in the matter. I like him because he has always called a spade a spade. There is no BS in his flying machines, they fly just great right out of the box. Sure the builder can modify 'em to his hearts content, but the end result will not be a better flying machine. It may be prettier and heavier, but it will not fly better.

Sig600 said:

.

Where is his (Van's) haste with the planes I see on the ramp at airports and airshows? RV's that were thrown together with zip ties and terrible workmanship? They're out there. I've seen some that make me shake my head and go "wow."

Click to expand...

I've seen a couple of really doggy RV's in my time too. I mean real dogs - so bad I was surprised they got off the ground. Sport Aviation doesn't feature those aircraft. It did feature the RV-10 that is the subject of this thread. From an engineering perspective, Van probably thought he needed to protect his customers and his business and discourage other builders from making some of the same choices.

Shoot, there are two old RV-ator articles on mistakes I made during my build. I wrote one of the articles and a friend wrote another. Sharing best practices (and identifying bad ones) is a key to safety in our hobby. Safety is paramount and needs to take precedence over egos.

Kyle

How? (And I'm not intentionally being argumentative - I'd really like to hear your opinion on "how"

Kyle,
I can appreciate your concern that many VAFer's have been recently discussing how to police our own awful safety record. Dick has been invited by the Feds to participate. Potentially flying overgross (or endorsing it) would certainly qualify. First order of business should have been to ask the EAA why they were trying to submarine his efforts. Second, he should have let the EAA and the judges have their chance to address it. After all, Sport Av is a much larger audience...VAF is talking to the choir. We all know of scary homebuilts, and scary pilots and scary gun owners etc.
I am not trying to be argumentative either Kyle. I just think he damaged the cause by naming names. All the did was move the focus from a potential problem (it is legal) to character assassination. Changed the whole point. Its not about Greg. Its about being careful when you make changes. Calculate your risks carefully. Thanks for your legitimate concerns. I think we all are.

Pete

I will let your post stand Uhhhhh....thank you I guess?

N546RV said:

I must admit, that seat belt bracket made me cringe.

Click to expand...

Under normal use, this rudder cable attachment will fail first. The cables take the load of applying the brakes, and that tab will not hold up...... this makes me cringe............ Not only dose the rudder fail, but you lost the brake with it.

The seat belt may never get a chance to be tested............... if the rudder cables are corrected.

gasman said:

Under normal use, this rudder cable attachment will fail first. The cables take the load of applying the brakes, and that tab will not hold up...... this makes me cringe............ Not only dose the rudder fail, but you lost the brake with it.

The seat belt may never get a chance to be tested............... if the rudder cables are corrected.

Click to expand...

I don't know enough about what the -10 pedal assembly should look like to comment on this one, hence why I didn't. I can't even really tell what's going on there.

As for the original article, I don't read it as hanging someone out to dry. What I get out of is a warning against making potentially uninformed modification decisions. As Van points out, these are experimental aircraft, and the builders are free to make modifications as they see fit. At the same time, they've done (I assume) exhaustive engineering analysis during kit development, and those numbers shouldn't be dismissed just because a builder wants more.

I suppose if I was in his shoes, I'd be worried about someone reading an article in a magazine, seeing that this "best in class" plane is flying with a gross weight increase, and assuming that that's OK without any additional critical thinking. And that's what I got out of it: "You can do whatever you want, but be aware of the potential negative consequences of going off the reservation."

What Price a Masterpiece

First, I agree with the position taken by Van and his tone and discussion of the subject airplane. And I think these things have to be said, because the editors of Sport Aviation magazine are not doing their job. Their article on the subject airplane simply gushes with praise about the beauty and craftsmanship of the machine. There is nothing said about whether the modifications and additions are well engineered or whether they compromise the intent and mission of the RV-10 design. Perhaps the best way to have handled this would have been to invite Van's Aircraft to comment on the airplane and the article and to publish those comments in a sidebar. At least there would have been some balance to the article and readers contemplating a similar airplane should be aware of the consequences of the compromises. And the consequences in this case are severe. I don't think most customers have any idea how hard an airplane designer works to achieve high performance coupled with light weight and a meaningful useful load. If they did they might not take so many liberties in the fitting out of their airplane.

As an engineer myself, I have been put in the position of customers "using up some of the margins" that I have used in the design. Usually it has taken the form of asking me what the "real" instead of the "nameplate" payload of the machine. I always stated very firmly that the "nameplate" payload is the only one there is. And as the customer walked away I knew very well that he was going to overload his machine.

I had a conversation with one of Van's engineers about this very topic and we both agreed that the "margin of safety" or "factor of ignorance" is the property of the designer, not the right of the customer to use however he desires. Van makes this point in his comments as he has a right to do.

Character assassination?

Peterk said:

I just think he damaged the cause by naming names. All the did was move the focus from a potential problem (it is legal) to character assassination. Changed the whole point. Its not about Greg.

Click to expand...

I believe one of the first sentences that Van wrote in his article included "....the absolutely gorgeous interior that Greg Hale built into his award-winning RV-10." Seems like an acknowledgment of Mr. Hales craftsmanship to me. Yes, Van then went on to focus on how the added weight and other modifications negatively affected the performance and safety of the plane - citing REAL numbers, no less. Van is, at the end of the day, an airplane designer, engineer, and enthusiast. You've got to realize that he sees straight past that fancy (heavy) interior (and yes, it looks great) and sees the issues that the weight causes. Van advocating "build it simple, build it light" is certainly not a new mantra.

I guess I just don't see the need to level charges of "character assassination" at Mr. V. The article was intended to call attention to the price one pays when adding weight (and making other modifications) to a plane that recently was in the press (again, not a new trend for Van.) So you're right...."It's not about Greg."

The best thing of all.....

In Australia we give Americans lots of stick for going on about the land of the free, and the right to free speech and all that hoohar.

But to be honest I read every single post and it made me smile because it was a testimony to people having their say.

The protective inventor, the over zealous builder, those that agree with Dads harsh words, those who say you leave him alone and those that just looked at the facts.

All of that got expressed and can be read by anyone with an internet connection. No one got litigated against ( I am hoping ) and some of us readers learnt a few things about design safety and testing the edge in a reasonable way or not.

Truth be told, every person had the right to say what they did.

This was a very good post, for more reasons than just what is relevant to aviation.

Will Sport Aviation print Van's comments?

I cringed when I read that article in Sport Aviation a couple of weeks ago. Glad I'm not the only one.

Probably enough has been said here about that airplane and the decisions made by the builder, so I won't add to that.

But I will say unabashedly that I think the editors of Sport Aviation should be deeply embarrassed for publishing that article as it was, glorifying that project as something to strive for. I hope they'll redeem themselves by publishing Van's comments in the next issue. Anyone know if Van submitted his article to Sport Aviation?

David-aviator said:

I am amazed at the skill of some builders. But that being said, the empty weight is an embarrassment. The airplane like so many Americans is obese.

No doubt Mr. Hale could build an RV-10 that would come in at 1600 pounds and blow everyone away. That would be impressive.

I suppose some prefer the expensive auto look, others a simple old pick up will do. But when it comes to an airplane, performance is what counts and obese airplanes, like obese humans, are not going to win the race. It may be pretty, but it will be last.

As the designer, Van would be remiss in not pointing out the aerodynamic and safety compromises of this particular RV-10. He really has not choice in the matter.

I like him because he has always called a spade a spade. There is no BS in his flying machines, they fly just great right out of the box. Sure the builder can modify 'em to his hearts content, but the end result will not be a better flying machine. It may be prettier and heavier, but it will not fly better.

Click to expand...

Knowing Greg's back ground, he knows what he's doing, and he's got the money to pay for the gas to haul around some Lexus seats if he so chooses. If he wants to top it off with 120 gallons and go non-stop to the moon solo, he can. If he wants to put just 40 gallons in and take 4 friends to the beach, he can.... in either case in complete comfort and in both cases within the build spec of the airplane. At no place did I see him say that HIS airplane could haul four people, bags and full fuel, but that the RV-10 could, and his will perform to that spec when he loads it as such.


If the end result of a builder "modifying to the hearts content" doesn't result in a better airplane, then every owner of a rocket, fastback, or anyone that put more than Van's spec HP in their airplane is wrong. Same goes for anyone with tip tanks, modified cowls, subaru engines, and on and on.


If Dick wants to take the "Experiment" out of Experimental then he needs to close the doors to his shop and move on, or start building certified production aircraft.... otherwise, when a kit leaves the factory his say in what it becomes ends at the door

Disclaimer, mine will be within recommendations, to Dicks recommended power setting, and operated within published tolerances. With engine/FWF/prop all purchased from Van's. Why? Because he designed it, and I trust him. However attacking his customers right to "free speech" has really rubbed me the wrong way. Didn't his original RV start off as a highly modified Stitts Playboy? Where was his vehement standardization to design then?

A few thoughts (long)...

I'll try to categorize my thoughts on this article:

The author's approach:
I definitely understand Van's desire to point out concerns about modifications which could affect safety or flying characteristics. I think his arguments were (for the most part) well rooted in sound design / engineering / testing practices. I also think it's a prudent business decision (from a liability standpoint, at the least) for him to stand on the side of "build it to the plans." Hopefully, however, he extended the courtesy to the builder that the article was forthcoming before actually publishing it. Ideally, the builder would have had the opportunity to provide a response to Van before the article was posted on the net. Only Van and Greg know whether that took place or not.

Design thoroughness:
Disclaimer: I'm only a mechanical engineer, not an aero engineer, and have never designed an aircraft myself. I have designed a huge amount of other stuff, though.

There are several points made in the article with which I disagree at least in part:

• Increasing the gross weight does not necessarily mean a decrease in safety. It does mean a decrease in the margin. Take the aerobatic RVs, for example. Increasing the gross weight (above Van's numbers) by 5% or 10% doesn't necessarily mean the aircraft is unsafe. It just means there is less margin for G loading. That might not matter one iota if the normal regime of flight is non-aerobatic. (yes I understand this doesn't apply to landing gear...I'm just trying to illustrate a point...the contrary point about unintended consequences is also certainly valid).
  
• While I'm sure many thousands of design and test hours went into the design of each of the various models, the article gives the impression that every fiber of these aircraft is thoroughly designed and tested. Having worked in the engineering trade for a long time I can say with certainty that a lot of the final product is arrived at through the TLAR* method...that and iteration. There simply isn't enough time to design everything to the Nth degree. Take something as simple as the seat backs in my RV-7A for example. The designer might consider these among other factors:
  • How thick should the sheet metal be?
  • How many corrugations are needed?
  • How deep should the corrugations be?
  • What shape should the corrugations be?
  • Which cross section of extrusion should be used for the perimeter framework?
  • Can we add lightening holes to them or not?
  • If so, do we need to flare the edges of these holes?
  • etc, etc, etc, ad infinitum.
  Does anyone really think a designer spent the weeks and weeks required to analyze all the possible permutations of these and other variables? In reality, I suspect some previous designs were considered, maybe a few rough calculations were made, then the designer moved on to his/her next task.
  
  Another example is the expression of concern about extra fuel capacity on flutter characteristics. While a valid concern, I submit that more than simple GVT at full and empty tanks is necessary to fully understand the flutter behavior of the "per plans" design. What happens when the tanks are half full...or a quarter full? I suspect that a flutter engineer would tell you that full scale, fully instrumented, destructive testing might be a good starting point to understand the interaction of structural rigidity, inertia, and aerodynamics that contribute to the flutter characteristics. And I'm not just talking about the wings...certainly there's interaction between all components...fuselage, tail, and all control surfaces included. On a scale of 0 to 10 (with no testing being a 0 and complete characterization of flutter behavior being a 10), Van would have to decide where his level of design and testing falls on this scale. Perhaps a 2 or maybe even a 3? The score for the builder's modified design would certainly be lower.
• There are lots of areas on RV's that are non-ideal (i.e. nose gear design, fuel vents, spin characteristics on the 3, 4, and 6 to name a few). A designer's job is to balance many factors such as mission, performance, range, weight, cost, simplicity, manufacturability, maintainability, and others. Most (all?) of these variables are on a sliding scale and interact with each other. The resulting product reflects how the designer weights each of these factors. Very often, there are no black-and-white answers. A modification made to a kit aircraft may simply mean that one builder applies a slightly different weight to these factors than did the original designer.

Transparency in design:
One of the problems with the present-day state of kit built aircraft in relation to the last bullet point is that the builders have little to no access to the knowledge and rationale used by the designers. Thus, it's frequently impossible to say whether a modification lives up to the original intent since the original intent isn't known by the builder making the modification.

The only solution I've been able to come up with is to adopt an "open source" model for kit aircraft design. Put it all out there for review by any interested party...notes, calculations, assumptions, design goals, analyses, DoEs**, test results, etc. Let others contribute their experience or feedback on areas of concern. Then those wishing to make modifications would have a good basis to start from and could contribute their results to the overall project for adoption (or rejection) by others.

Maybe I'll do a design of my own using this model after I retire. (don't hold your breath ;-)

Thanks to Van, Greg, and all those that have posted. It's been a good, thought provoking discussion.


*TLAR - That Looks About Right
**DoE - Design of Experiments

An interesting article

It is quite easy to read it as a one way 'attack' on Greg... however, to me he is using the article to express concerns about how many modify / specify RVs. Quotes:

By way of contrast, we wonder what basis Mr. Hale (or any other builder who uses a higher-than-recommended gross weight) uses for establishing the 2800 lb gross weight of his airplane? If it isn?t based on the same science and testing, we simply cannot recognize it as valid, and neither should anyone else. Any ?penciled in? gross weight increase is just wishful thinking. The laws of physics are not repealed by wishful thinking.

Click to expand...

Yes - the experimental scene in the US is there to allow freedom. Van's respects that to a degree:

We all know that builders of Experimental Amateur-Built aircraft have the right to make changes to their aircraft at will ? whether or not their changes are based on good science. If they choose to operate the aircraft with a lesser or unknown margin of safety, that is their prerogative.

Click to expand...

He does add however:

any passengers carried in that aircraft will be exposed to the same unknowns that the pilot has accepted for himself. We feel that this is a responsibility often overlooked by pilots. While they may be willing to accept certain risks for themselves, what should their responsibility be to their spouses, friends, children, and grandchildren?

Click to expand...

Do those who increase the Gross Weight / make structural changes / says this is a Vans RV-x but I have eroded the designers' safety margins, truly explain that to their passengers?

Summary - it is a 'skim reader' who sees Van's post as criticising Greg and the specific RV-10. It is really aimed at many of us on (and off) this forum (and I'll include myself) - all this RV-10 offered was a public example of thoughts he has hinted at in articles before

Wow!

This article and the resulting backlash/support is more awakening than a bowl of ice water to my face!

Van, however, does not have his head buried in the sand.

Best,

I'm with you Pierre. first thing I find reading the posts this morning is this storm.

I appreciate Greg's ability, skill and recongnize his right to build the RV-10 any way he wants. I appreciate Sport Aviation and their desire to focus on some spectacular examples of what can be built by amateurs. And I respect Van for pointing out the flaws inherent in straying from the book.

I think most readers can read between the lines of all three and take away what they want. I feel for Greg and for Van. Paul's right. You put yourself out there, you invite examination.

f1rocket said:

snip.... I feel for Greg and for Van. Paul's right. You put yourself out there, you invite examination.

Click to expand...

Agreed. There are thousands of -10 builders looking at others for ideas on how to make their planes unique. Van is trying to make folks aware of the unintended consequences that can pop up by deviating from the plans.

The next to the last paragraph floored me...


My cube worm brain doesn't go straight to the math like an engineer's does. I appreciate and concur with what Van is trying to do - improving the chances of his customers living a long, happy life.

br,
dr

ps: The civility in this post makes me smile. Thank you again.

A new guy perspective

Working in a technical environment and also new to the forum I appreciate all these posts. I used to worry when I saw technical experts disagree strongly, but I've come to realize that reasonable strong arguments on both sides of an issue can cause people to do their best thinking.

I wonder if some of these posts are based on some long simmering disagreements.

As a new guy who wants to purchase a built flyer this thread has given me much more to consider. I'd like to spend time with experienced builders looking at planes and learning the weak points.

I can't afford either a perfect or unsafe plane.

flytoday

I think the cable attach issue and the seatbelt attach modification could have been pointed out in something like the RVator, without pointing out a specific builder/aircraft. They are potential issues, and should be corrected. No need to single out a specific plane. I didn't see the SA article, were these points noted in the article, or did van single them out?

Carring too much fuel and too much weight has been beat to death here, and we are all aware how van feels about those issues.

One of the best threads in VAF history.

Regardless of what we think of the article, the builder, or what Van wrote about the plane, it certainly brought needed attention to the subject of aircraft design specifications.


Do we have a "Best Of" category?

I sure would rather get beat up here on VAF, SA or by Dick VanG, than by.....physics!

flytoday said:

I wonder if some of these posts are based on some long simmering disagreements.

flytoday

Click to expand...

Welcome To VAF!