# What could be done to reinvent the Affordaplane to a more homogeneous project?

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#### erkki67

##### Well-Known Member
Erkki,
Ref your last email: The straight back would have the same dimensions as the ptp AP except for raising the tail post to meet the upper tube. ...at least on my quick and dirty sketch.
Always loved your drawings and sketches!

#### erkki67

##### Well-Known Member
and what about the position of the lower LDG suspension support tube, the one from the engine support to the lower cockpit longeron?

#### Andy Garrett

##### Active Member
Wow! I just read 30 pages of this thread! Seems like it has been quiet for a couple of months, but I have some thoughts I'd like to share.

Aerowerk: You had a question about the two different airfoils used by the AP. The aluminum tube version with the straight back is a common UL rib. I learned reading Herbert Beaujon's How To Build Ultralights that the fabric stretched between the ribs which dips and undulates, is what creates a majority of the 'proper airfoil' shape. This was surprising to me. Again, according to him, this type of airfoil is only slightly less efficient than a more traditional one and the wing can be built much lighter.

#### Andy Garrett

##### Active Member
As to the original post which calls into question, the nature of the AP design, I interpret the use of the word 'homogenous' to mean 'more aircraft like' and less 'this is what I had laying around my garage'.
I own several sets of plans which I have enjoyed studying over the years, including the Pietenpol. Go onto a Pietenpol forum and ask about mods or changes and you will be met with a chorus of JUST BUILD IT TO THE PLANS! IT'S BEEN WORKING FOR 80+ YEARS! It's almost cult-like. Even the Pietenpol family don't want you calling your plane a 'Pietenpol' if it has been modified beyond the plans. So, it's refreshing to see a thread committed to discussing plans modification without all that backlash.

To my knowledge, this design still has a perfect safety record 20+ years and counting. I don't know how you call that anything but a success.
I owned an Airbike. Specifically, I owned the one RadfordC built in '97. He is correct. They fly great (when built well). But, at 260lbs behind a 40hp Rotax, climbing was iffy on hot days. But, I loved the plane. I just liked looking at it sitting proud in the hangar. That line that went from the upper longeron of the tail all the way through the cockpit and picked up perfectly by the top edge of the cowl over the inverted engine and tapered down into the spinner. It was more than function. It was beautiful--almost fighter-like. The problem with the Airbike and other 'knees in the breeze' aircraft, is just how much drag the knees create. They are like spoilers! I could steer the plane by leaning one knee out farther away from the centerline than the other! Flying for more than 15 minutes was tiresome as you tried to keep those legs tucked in close to the fuselage (made worse by my 6' 2" frame which gave my legs a pronounced bend). Once your muscles give up and you let your legs relax, they hang out there like you are doing yoga, funneling all the air which is pushing them outboard up your inner thighs, hitting you square in the chest. It's like a drogue chute. Some Airbike pilots actually strap their legs together to avoid this phenomenon--a trick taught to me by Paul Fiebich who has well over 1000 hours in his legendary machine.

This is what led me to search for a different solution. I sold the Airbike and discovered the Affordaplane. It had the same general look, though not as refined. It could be built with an inverted engine and the longeron line could be emulated with minor adjusting if I desired. And it had something else... It presents itself with open arms and says, "You can build me". The Airbike and Legal Eagle require welding. Not everyone has that skill or equipment, but everyone can drill holes and turn a wrench. The visual impact of this design on those even halfway considering a plane build cannot be overstated. No other aircraft, IMHO, even compares to the way the AP encourages a prospective builder with just a photograph. That's powerful stuff.

There have been a handful in this thread who question the engineering or the credentials of the designer. I understand, but let me nod again back to that perfect safety record. #nothingburger

Now, there are some weird choices in the plans--choices that many builders have chosen (smartly) to ignore. Darren Scarlett did what I feel is one of the best AP builds I've seen. The way he set up his controls did a good job of marrying Airbike design with the AP. The Rube-Goldberg stuff in the plans..., no thanks. But hey! This is experimental aviation! We can do that! This isn't the Pietenpol cult!

One of the things I like most about the AP is what many here have complained about--the gussets. I realize that those complaints were largely about weight, but I will build LSA. I have no problem with that. I just think the gussets are cool! I'm a knifemaker and retired tattoo artist, so I am VERY aesthetically driven. Those gusset plates with all the bolts or rivets give the plane an almost 'steampunk' look which suits the 'cobble me together' appeal. I might even paint it 'rusty' just to play up the effect.
I do love the Pietenpol tail, so I think I'll use those shapes while maintaining the proper surface areas. The aluminum tube spars and ribs with metal (not plastic) connections, and either an Airbike/Aeromax style landing gear or something like the Excaliber's ingenious suspension system will also likely find their way into my build. Cable and pulley systems seem especially suspect on open system designs like this one, because anything can get in there and muck up the works. I'll use the Teleflex cable and push rod set-up like the Airbike. Most importantly, I will beef up the seat mount. Bolting a seat to a 2" tube seems risky for a pilot of considerable weight. I know the tube will hold, but that wrenching/twisting moment caused by entry and exit as well as just leaning and adjusting could cause stress on the structure of the seat itself. I would possibly extend tubes from the landing gear crossbar diagonally back to the bottom of the rear wing pylon. This would give three seat-mounting points and spread than load out. I might even use something narrow like a motorcycle of bicycle banana seat. A rusty all metal tractor seat would add some character!
Anyway, sorry for my lack of brevity, but that's how I would 'homogenize' the design and give the construction methods an aesthetic purpose in the final product.

#### GeorgeG

##### Active Member
Preach, Reverend Andy!!! Amen, Brother!

#### Victor Bravo

##### Well-Known Member
Speaking as one of the people who called the design into question, and got napalmed for it by people who I respect, I must honestly say that I make no apology for calling things into question. Every bit as much as other people make no apologies for mindlessly repeating the aircraft's safety record. Here is my reasoning why:

Any aircraft's engineering or design can and should be called into question. If you call the RV-3 through RV-14 series from Van's into question, and demand to know who and how it was engineered, you will find that R. VanGrunsven is a degreed engineer, and he has a large amount of calculations to back up the engineering. Not that the RV is perfect (it isn't), but that the effort to engineer it was made.

If you call the Flitzer biplane, the Hovey Whing Ding, the Vari-Eze, the Bearhawk, the Cassutt, the Sonex, or the Midget Mustang into question, you will eventually find that the engineering was done by someone with the ability to do it, and somewhere in a dusty drawer in the corner of their hangar is the notebook with the calculations in it.

When there's not a direct, legitimate, factual answer, we have a right to dig for the truth. The builder of that aircraft also has an equal right to build and fly it anayway, whether there's engineering or not.

The aviation community also has a right to ask about this stuff, especially when we are "looking out for" someone, or even when we're looking out for someone else as much as our own freedom to fly (like on this forum).

#### Andy Garrett

##### Active Member
Your point is well taken Victor. Having confidence in a design starts with having confidence in the designer--I get it. But if you will indulge me, please allow me to make a few observations.
If a guy wants to fix his own car, he buys the Chilton's manual, and he gets to work. No one questions his credentials or asks to see his ASE certificate. He is allowed to fix his brakes and drive through all the school zones he wants to. But in aviation, a much different attitude prevails. Levels of credentialing pile on top of one another just to safety wire a bolt and sign it off for return to service. Now for commercial aircraft, this makes some sense. The public expects nothing short of extreme diligence in such matters, especially for high speed, pressurized, passenger aircraft. Likewise, heavier GA aircraft with large fuel loads and which fly over populated areas, need careful maintenance and that work should be closely monitored. These aircraft need to be engineered to the highest standards by qualified professionals.

However, my belief is that these uber-vigilant attitudes toward engineering standards and credentialing at one end of the aviation spectrum (where they are crucial to public safety), have unnecessarily incumbered efforts at the other end of the spectrum, where they are unnecessary.

The world of the Affordaplane is flight at the extreme low end of the performance envelope. It's difficult to go much slower and with less moving mass. Thus, the risks would be hard to reduce beyond that in powered flight. The plane carries a single person and forces on the building materials are miniscule compared with even mid-level GA aircraft like a Bonanza or C-182. This type of aircraft represents the minimum threat for structural failure due to aerodynamic force, and the minimum threat to anything below should such a failure occur.

So, with the risk established at 'very low' (pilot error excluded), we can ask ourselves: Do we need engineering degrees or A&P certificates? I argue that we don't. This is experimental aviation after all. I submit that anyone who can read a book and do some math, can design and build a safe aircraft. Many publications exist to share knowledge on the engineered specs of the various building materials, so those numbers are easily known. Likewise, many books exist to demystify the world of aerodynamic design. Tony Bengelis comes to mind. As does Herbert Beaujon who's excellent website can be found here: http://www.beaujonaircraft.com/index.htm
The answers are out there for anyone to study. One doesn't need an expensive engineering degree to be granted access to this knowledge. If Bernie Pietenpol designed a successful plane 60+ years before the internet, then there's no limit to what a determined soul could accomplish today.

But..., this is aviation. This is a world where man and materiel are measured by such things as ratings, endorsements, hours, degrees, V-speeds, drag coefficients, etc. Every single attribute of a pilot or an aircraft is reduced to a series of numbers, and anyone who scoffs at a number is branded as 'irresponsible' or 'reckless'. I understand. Math rules in this realm, and the assumption is that a person without the credentials lacks the abilities. But at this end of aviation..., where the speed, mass, and energy are as low as it gets in powered flight..., where the idea is to embrace experimental aviation and foster innovation..., where even the worst mistakes can be mitigated with relative ease by way of a BRS parachute..., do we really need certifications and degrees? According to the FAA, we don't even need a pilot's license if we build 103 (that's how threatening they find it), so why should that same 103 aircraft need a complete engineering 'prove-out' from some cat with the right credentials? Anyone can do that math.

Yes sir. You have a right to question and, "dig for the truth" as you put it. That should be a simple as sitting down with the known numbers and do some figuring, or trusting the opinion of someone who already has. If I understand your concerns correctly, you simply believe that those numbers haven't been reviewed by a 'qualified' person--with that 'qualification' residing only within someone possessing an aeronautical engineering degree. I respect that. Yours is likely the opinion of many in the aviation world, especially those who cut their teeth in certified, higher-performance aircraft. However, while I respect your point of view, I disagree with it. I think that at this level, the person who can be responsible and resourceful enough to build their own aircraft, can also acquire and understand the knowledge needed to design it as well--or in this case, to assess the design of another with a critical eye, a calculator, and a sharp pencil.
If the dream of making aviation affordable for the common man is ever going to be realized, then changes in attitudes toward expensive credentials and certifications will have to occur. Then maybe we can not only build a safe airframe at low cost, but also buy an engine like the 50hp Hirth F-23 without spending more money than we would on a complete 350hp LS1 Corvette engine. Some things in this world just make no sense to me.

Have a great day!

#### wsimpso1

##### Super Moderator
Staff member
Log Member
I am sort of in between you guys. The engineering methods and calculations can be learned, but even folks trained and experienced make a mistake here and there, and folks without a lot of training in the disciplines are MORE likely to make significant mistakes.

For designs that have a few out there already, well, I would be WAY more interested in service history of the type. There is almost always a user group somewhere. If their flight characteristics are poor or things break or they have other issues, you should be able to know about it. If there are known issues, sometimes there are known fixes too.

While a decent recovery parachute with current endorsements on the pack and propellant area comfort, there are things that it will not save you from. Some airframe failures will prevent a good deployment, and some engine failures occur too close to the ground (or tree) to get the parachute deployed. I would want to know that the airframe and power system is sturdy enough everywhere that regular failures will not happen. I would want to know when buying a new ship that they had someone do a review of the structure and that it will survive engineering scrutiny, which includes both calcs and good practices.

Now if you are happy buying a Part 103 vehicle number 2 from Joe's Lawn Furniture on the basis that Joe's vehicle number 1 has only had a couple things break in its 10 hours, you must be way more comfortable with risk than I am. I have a different attitude about vehicle #12 when the first eleven are still flying and the owners rave about them.

The neat thing about it is you get to make up your mind for how much risk you are willing to take.

Have fun guys.

Billski

#### Aerowerx

##### Well-Known Member
... If I understand your concerns correctly, you simply believe that those numbers haven't been reviewed by a 'qualified' person--with that 'qualification' residing only within someone possessing an aeronautical engineering degree. I respect that. Yours is likely the opinion of many in the aviation world...
Knowing something of the history of the AP, my viewpoint is....

The Texas Parasol is a better illustration of the problem. The designer claimed to have done calculations, but never let anyone see them. He also claimed that, right or wrong, there have never been any failures. When questioned on this he became beligerent.

You are free to design your own planes, and you should do some degree of calculations. And, if i was doing it, I would welcome a review of my numbers.

As for the AP, this would have been beneficial. There is a group in Canada that took on the task. They submitted the design to a "qualified" person, who found several areas that could be improved (Main spar comes to mind).

Moral of the story: Anyone doing their own design should at least have a "sanity check" of the design by a knowledgeable person.

Side note: When I graduated with my BSEE, there were guys in my class that did not know how to solder. My point is that a degree only says you know how to read a book, not that you are qualified in the fundamentals.

#### Victor Bravo

The difference is when you start selling plans to other people. That comes with a far greater obligation to have the safety of the structure verified. Even if the designer does not have a formal degree, but can run the numbers... show the $@$-&$numbers so someone else can verify it. #### BJC ##### Well-Known Member HBA Supporter Andy: What counts in designing an airplane is one’s ability. I know people with advanced engineering degrees who do not have that ability, and I fly an airplane elegantly designed by a non-engineer who had lots of practical experience plus some top notch engineers who checked his work. I know a man who put lots of work into several very light / ultralight original design airplanes. He was fortunate to have survived them. He went on to build a proven E-AB design from plans he bought. Even at the ultralight end of the aviation spectrum, the airplanes fly high enough and fast enough to kill you. Note, also, that even though you have classified the forces on an ultralight structure as “minuscule ...” that is not relevant. There have been many, many one-off / prototype ultralight fatalities due to structural failures, when those minuscule forces resulted in material stresses that exceeded the material’s ultimate limit. While I’m sympathetic to your argument about the AP, the designer sell plans to the public. My judgement is that selling plans and representing the airplane as safe, easy to build and easy to fly requires a higher degree or rigor than a one-off where the builder is the only one at risk. Please note that I have no personal assessment about the AP; my comments are about designer responsibility. Tell us more about your “Pietenpol -ish thing.” BJC #### Andy Garrett ##### Active Member All good points my friends! I thank you for your indulgence. I'll be building the AP with the mods I detailed in an earlier post. I'm comfortable with the aluminum rib wing structure (quite common to planes in this class), and the changes I plan to the fuselage excite me. The safety record and documented flight characteristics put any 'soundness of design' questions in my mind to rest (far more than the VP-2 I was considering). And the alleged general attitude of the designer makes little difference in what I do with the well-proven plans. The only thing that preventing me from beginning is the engine. It is my belief that a plane of this size with this limited performance, should be built around the power-plant rather than the engine being a 'whatever I can afford' plug-in, to be determined later. But that's just a personal parameter. #### erkki67 ##### Well-Known Member All kind of AP-isch planes. I'dlike to have the upper and third planes combined, this is getting very interesting! #### Andy Garrett ##### Active Member Looks like we cross-posted BJC. I agree that sold plans should represent a safe aircraft if built STRICTLY according to those plans. The AP's record clearly indicates that, without exception. Furthermore, the plans have proven very flexible as many modifications (some extreme, like a full VW engine) have been incorporated without a documented safety incident. Plans with large margins like that allow for a considerable degree of creativity. I only wish to forward the idea that regardless of the plans, the onus remains solely on the builder. If we dare to believe ourselves capable of such an endeavor, then we better know our stuff. Since mine will be EAB, I'll have the benefit of an airworthiness inspection as some degree of confirmation (or condemnation, lol). As for my Pietenpol references..., I love that plane, but some of the online personalities associated with that design can be a bit intolerant. The mantra of 'BUILD IT TO THE PLANS' couldn't be less inspiring. If every Piet was the same, they sure as hell wouldn't be very interesting. One of my favorite things about home-builts is comparing the creative choices made by each builder within a single design. That is what inspires me. #### erkki67 ##### Well-Known Member My favorite engine for such a concept, wit a 5 US GAL, this means about 3, 5h of flight time, more then enough! #### BJC ##### Well-Known Member HBA Supporter I only wish to forward the idea that regardless of the plans, the onus remains solely on the builder. You and I agree on that; juries have disagreed. BJC #### Andy Garrett ##### Active Member Your comment triggered my curiosity, so I just spent the last 45 minutes searching and reading everything from regs, to EAA articles, to articles in Air Law & Commerce. There is a fair amount of guidance and compulsory 'warnings' about selling homebuilt aircraft even if you didn't build it. There is also a lot of info on product liability concerns for component manufactures and sellers and particularly, kit manufacturers and sellers (though nothing regarding plans only scratch built aircraft). One fairly recent and well published case was a suit for$35 million against Vans after an RV-10 accident in Oregon. The case was dismissed.

Other than that one suit, I can find nothing.

Perhaps you aware of a particular case...

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#### Aerowerx

##### Well-Known Member
View attachment 91750

My favorite engine for such a concept, wit a 5 US GAL, this means about 3, 5h of flight time, more then enough!
It would be nice to know if this thing had a name???

#### Andy Garrett

##### Active Member
BTW, did the Ranger Fritz was designing before our eyes ever get another thread? I liked following that development.

#### BJC

##### Well-Known Member
HBA Supporter
Other than that one suit, I can find nothing.

Perhaps you aware of a particular case...
There have been several against major kit manufacturers, including Stoddard-Hamilton and Vans.

One against a designer is mentioned here https://www.upi.com/Archives/1989/01/11/British-firm-sues-Voyager-pilot-Rutan/1062600498000/

I am aware of others, too, but finding records of them on the www is difficult unless one knows where they were filed. Perhaps others here have some memory.

Note that filing suit only takes some paperwork.

BJC

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