Two things that were badly wrong with the airplane, drawn the way they were wrong. Both were caught on paper. Nobody had cut any wood yet, which is the only reason they were cheap.
Do not open the answer. Give it a real minute. Ask yourself what would happen if somebody actually built the thing exactly as it is drawn.
Out loud, or to somebody in the room. Saying it is harder than thinking it, and the bit you stumble over is usually the bit you had not really worked out.
Underneath each one is what actually went wrong, what it was changed to, and which round of review caught it. If you got a different answer that also breaks the airplane, you are right too. Most drawings are wrong in more than one way.
These are sketches of the problem, drawn for this page. The real sheets stay off it until somebody signs them.
Here is the airplane from above. Four engines hang under the wings, each one on a wooden pin that goes up into the wing. Look at where the engines are. Then look at where the wood is.
All four pin holes were drawn out in front of the wings, in the air. A shop building from that page would have drilled four holes into nothing, and been left holding an engine with nowhere to put it.
Redrawn, every bore sits fully on wood. The inboard one has 12.4 mm of wing between it and the front edge and the outboard one has 11.8 mm. Those two numbers are on the sheet now, because a hole close to an edge is the one that splits when somebody pushes the engine on.
Rev A drafting self-check, 1 September 2026. Eighteen findings that round, three of them serious. This was one of the three.
Both wings are one single plank that slides in sideways through a slot cut all the way through the body. The slot is 100 mm tall and the two dashed lines carry that height across the drawing. Every part of the plank has to stay between those lines to get through. This one never can. Why?
Because the back edge swept away from the very middle. Push the plank in and its back edge drops below the bottom of the slot almost at once, and wood does not go through wood. No amount of shoving fixes it, and neither does sanding, because the wood you would have to take off is the wing.
The back edge was redrawn straight for the first 71 mm either side of the middle, and only swept from there outwards. Every slice that has to pass through the slot is now exactly 100 mm, the length of the slot. The sheets carry a note telling whoever builds it not to tidy that straight piece away. Next time you are under a real jumbo jet, look at the back of the wing where it meets the body. It has the same straight piece, for its own reasons.
Three-lens adversarial review, 2 September 2026. Thirty four findings, and this was the one marked critical.
That is the end of this one
The word for what you just did is review.
A review is somebody who did not draw it going looking for what is wrong with it. Sixty eight things came back on this airplane across three rounds, six of them badly wrong. Every one of them was found on a page, which is where mistakes are cheap. The same mistake found in a workshop costs wood, and found in a box costs a customer.
Where to go now