# What's wrong with the Affordaplane?

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#### TFF

##### Well-Known Member
If the wing has to be overhead build a Himax. When one has to have a specific material, it is best to go with something proven than be picky on high middle or low wing. When you finish the first project and are putting around, build the better plane. If you never build the better plane, you still have one that works.

#### Speedboat100

##### Banned
Or, more correctly, how would you fix it?

Like so many others, I'm intrigued by this simple-looking airplane and interested in building something like it some day. I don't know if it's the in-your-face simplicity of the airplane, the excitement of flying so exposed (while still in a normal-looking plane), the idea that it could be the modern descendant of the primary glider or just the cost-effectiveness implied by its name. Point is, it's alluring.

The trouble is, they don't seem to work. I've read about how they're basically guaranteed overweight and I too can see the somewhat questionable load paths. I've never seen a picture of one flying higher than ground effect and even those are hard to find. It doesn't seem like there's a shortage of A-Planes being built but even then no two are alike.

So fundamentally what's wrong with the A-Plane? Are they victims of builders making them 'better' without really knowing what they're doing? Is it just an overweight ultralight that would be better off re-branded as an LSA with maybe a little more wing? Is the whole concept just fundamentally flawed? Is it a wildly under-engineered scam? A zillion plans at just ten bucks a pop adds up, you know.

Let's say it can be fixed. How would you do it? What are the most glaring problems with the Affordaplane's design? What would someone need to keep in mind when designing something similar?

Here's what I have in mind: a flat-fuselage version of some classic lightplane. It can be a Cub, Champ, Stinson, Rearwin, Cabin Waco or whatever but I like planes with character and this is the lazy way to achieve that. Ideally I'd like the rear fuselage covered but since you apparently can't do that on the A-Plane maybe there's a good reason not to do it on any plane (why is that, anyways?).

Other points to tick off:
-Part 103 eligible
-Simple construction (I have riveted tube in mind for the majority of the structure)
-Materials for large parts should be obtainable in just about every major city, small specialty stuff can be mail ordered, of course
-Four stroke engine like a half VW or something (this would of course limit the weight of the rest of the plane)
-Capable of hauling a 230lb, 6' 5" guy into the air

I'm not looking for anyone to do the work for me, just a reality check to see if this is even something attainable.

-Tim

I just watched an YF-23 video...and they told (at 21:30) the hardest part is to pack everything nice and tight.

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#### Speedboat100

##### Banned
In comment it says that it can be built at 3500 usd.

Afford-A-Plane indeed still ?

#### Speedboat100

You must be using some very simple math. How do you figure $17,000? #### BJC ##### Well-Known Member Supporting Member You must be using some very simple math. How do you figure$17,000?
I can verify that the math is correct: 5 X 3,500 = 17,500.

However, I have no idea where the numbers came from.

BJC

#### erkki67

##### Well-Known Member

Herewith almost all problems of the AP are resolved. ( Fritz interpretation)

#### Speedboat100

##### Banned
I can verify that the math is correct: 5 X 3,500 = 17,500.

However, I have no idea where the numbers came from.

BJC

I have been in contact with certain operators regarding my innovations...and they told me if you wanna design and build something that is the equation. A product has to cost one fifth of the retail price to make to be able to make business with them.

BJC

#### galaxy engineer

##### Member
I hate that this thread died...Lots of great exchanges in here. I have been inspired since the early 2000's (when I bought my first set of plans) to build an AP because it is so **** simple but it is heavy. I don't want a heavy ultralight. I would like to build one but put it on a diet. When I look at the Legal Eagle or the Airbike (especially the Airbike) I see what they did in the fuselage and the load paths and the blah blah blah that the Afordaplane is blah blah blah. It is always the same ol discussion. I like that erkki67 (above) actually put something to paper and presented here. Thank you for that.
I have ideas of my own but I am skeptical that as the airplane is now generally designed and built with the materials used getting the weight down is a huge undertaking without a major design change using different materials and blah blah blah. By the time I do all that then it is really not an AP anymore but just another plane inspired by the AP and not as simple to build and departs from Dave Edwards original concept of easy and affordable. The upside is you could take this lil plane into combat because it is so tough and over designed. I read somewhere (probably this thread) that the fuselage is probably an 8G design under a 3 or 4G wing on top of a 2G landing gear.
I'm guessing the wings would finish out around 25 to 30 pounds each and an engine around 100 pounds give or take so that sure does not leave much for everything else (as with any ultralight I suppose). Even if a builder stuck strictly to the newer "Ultralight Version" of the AP plans I think it would be closer to an ultralight proper but still skeptical.
Maybe it is what it is and I should just build and fly it as proven by several flying examples. I would be flying so much sooner if I didn't have to do all the head scratching. Maybe I just build two fuselages or three or four or whatever until I can scrape the weight off of it. I love this plane...I always have cuz of its simplicity to build...no welding...not complex jigs...or tools. Just a flat table and some shop space just like my RC days when I was younger.....
I hope this revives this thread...
Thats bout it
Brett

#### Victor Bravo

##### Well-Known Member
Supporting Member
The "blah blah blah" part is what causes most of the arguments about the Affordaplane. Aerodynamically it is just fine. Apparently it flies well enough. It is certainly affordable compared to any other choice. It can be built very quickly compared to others... so....

With all that going for it, why would there possibly be such an uproar and argument over this aircraft, and why would the majority of all that uproar be coming mostly from people who have been around airplanes and flying for a long time?

Maybe Daphne, Fred, Velma, Shaggy, and Scooby can hop into the Mystery Machine and answer that question.

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#### galaxy engineer

##### Member
The blah blah blah is meant to represent all the arguments...I don't understand the uproar though. It seems it should be a fairly reliable design though heavy as eff. I would love to find a lighter design and as easy to throw together as the AP. With all the examples flying as of late I am betting exactly "0" are flying at or under 254. I don't bash for that I only offer my observation. Other than that is is a perfectly fine example of what it is intended to be. I am going to build it. I am going to try to stay under 255 even if I have to cheat using the BRS loophole. LOL! At least we dont have to foot launch it anymore....hahaha

#### erkki67

##### Well-Known Member

An interpretation of Daniel Valero, have a closer look at the engine!

#### galaxy engineer

##### Member
View attachment 124285
An interpretation of Daniel Valero, have a closer look at the engine!
Nice...!
So a couple of questions...
God knows I am not a structural engineer but....
Could the lower longeron of the fuselage be replaced with two 1" T6 tubes held to the side of the lower forward fuselage with conventional tube attachment techniques like a series of stainless steel stirrups and then the tube longerons would bent upward to the bottom of upper longeron below the horizontal tail surface. this would eliminate some weight in some of the heavy aluminum attachment plates and the 1/4 inch AN hardware associated with them. This would also give a small bit of 3rd dimension to the aft fuselage that would be probable 6" wide where it attaches to the lower aft fuse and tapers toward the tail. The Z bracing could be 1x2 rectangle tube and 1' tube as it moves toward the aft taper and be placed fairly conventional location as per plans.
Problem #1 that I see is as you lighten the tail we will have to either shorten the nose or move the pilot seat back to keep the CG manageable.
Question # 2...since we would have to shorten the nose a bit and redesign it slightly could you not eliminate the larger and heavier 2x2 over head cockpit tube to a much smaller, lighter structure since this doesn't need to carry much load. I take an example from the Airbike and Legle Eagle. I think as designed and without the 1" front down tubes from the front down to the landing gear support this would have to be kinda beefy. Daves original design did not have the down tubes and were added later when he noticed that the landing gear support trunnion was showing signs of bending upward due to landing loads. The support tubes were added to distribute the loads early on during test flying. With the triangulation in the front and properly designed in the back I see this as a huge place to save weight in the airframe. Much smaller lighter structure could do the job here maybe.
Question #3...to Shorten the fuselage could you not bring the front "windshield center post" straight down to the bottom forward corner of the fuselage and make it 1x2 instead of 2x2. then about midway down a triangulation brace that extends aft between the pilots legs to the bottom 2x2 of the fuselage. Then for a motor mount 2x2 angle could be used on either side of the fues for the motor mounts. This would have the benefit of moving the motor aft a few inches to help counter the lighter tail design.
All that said it is almost a complete redesign of the AP fuselage and could depart the original intention of the plane though I see it as maybe possibly having the benefits of making the AP not only lighter but possibly even cheaper to build.
Maybe I am wrong in thinking so I ask...
Brett

#### Batjac1

##### New Member
I wish I had enough math to do a structural analysis of this plane. I'm a maintenance guy, not an engineering guy. But as overbuilt as this is, I don't see why more 2"x2" can't be replaced by 1"x2" tubing. If I had the math, I'd do a structural with all tubing being 1"x2", and then if anything is insufficient I'd back it out to 2"x2". Can anyone point me to someplace where I could educate myself on how to do the analysis? I'm not dumb, just ignorant.

Mark

#### erkki67

##### Well-Known Member
I wish I had enough math to do a structural analysis of this plane. I'm a maintenance guy, not an engineering guy. But as overbuilt as this is, I don't see why more 2"x2" can't be replaced by 1"x2" tubing. If I had the math, I'd do a structural with all tubing being 1"x2", and then if anything is insufficient I'd back it out to 2"x2". Can anyone point me to someplace where I could educate myself on how to do the analysis? I'm not dumb, just ignorant.

Mark
I’m exactly in the same position, I repair flying torches but can’t do the math for em!

#### Dana

##### Super Moderator
Staff member
I wish I had enough math to do a structural analysis of this plane. I'm a maintenance guy, not an engineering guy. But as overbuilt as this is, I don't see why more 2"x2" can't be replaced by 1"x2" tubing. If I had the math, I'd do a structural with all tubing being 1"x2", and then if anything is insufficient I'd back it out to 2"x2". Can anyone point me to someplace where I could educate myself on how to do the analysis? I'm not dumb, just ignorant.
People say the A-Plane is overbuilt, but other than casually looking at (but not analyzing) the questionable area around the cockpit, I haven't done or seen an analysis indicating that, either.

But things aren't always obvious. For example, in a column structure, buckling of the tubes is generally the critical failure mode. Assuming 1/16" wall, a 2x2 tube is nearly five times stronger in buckling than a 1x2 tube. Even if it is overbuilt, I doubt it's by that much.

I haven't read the book myself, but I've seen "Stress Without Tears" recommended as a good primer on the subject without being too heavy on the math. But there's no getting around it, stress analysis requires a certain level of math understanding.

#### galaxy engineer

##### Member
I have no doubt that as built the A-plane fuselage will survive similarly to anything else out there an is way more than enough to fly safely at 55mph (give or take) once all the bracing and drag wires are installed. That’s not the problem as I see it. I think it could be lightened up but let’s face it…because we don’t know the math exactly it is over built to avoid it. Throw on a proven wing design and now it’s bullet proof. It flies and it flies well but could be better if an engineer took over. The problem with an engineer is they don’t care so much for ease of manufacturing as much as cost and strength. Time, quality, or money…pick any two!