Why You Can’t Use 737 Single-Seat Parts for the Dual-Seat Cockpit

The 737SS Glarewing and MIP in the dual-seat shell. The Glarewing extends too far into the cockpit, making it impossible to fit against the window opener/handle  

Hello everyone,

I wanted to share this Patreon post from June 15th with everyone on this site. I have analysed the AI questions and answers, and the most frequently asked question over the last 30 days is: "Can I use the 737SS gearwings in the dual seat shell?"

This post comes from a realisation that has completely shifted my understanding of why so many of you have been struggling with the dual-seat construction. I want to take a moment to express my heartfelt appreciation to the three Patrons who shared their photos, comments, and even a beautifully written 31-page essay detailing their experiences with the dual-seat build. This feedback has been invaluable, and while it was tough to see some of these struggles unfold, I view this as an essential learning experience—one that will allow me to improve how I communicate these differences moving forward.

The Root of the Problem

It wasn’t until 2000 hours tonight that everything suddenly fell into place. For the past two years, I’ve been puzzled by the difficulties people faced when attempting to build a dual-seat cockpit. Tonight, after reviewing several images, I finally saw the issue firsthand—and it left me feeling a profound sense of terror.

Initially, I thought this was a minor issue related to the difficulty in constructing the dual seat. However, after seeing the extent of the modifications people have carried out using 737 single-seat parts in the dual-seat configuration, I realised this is a major compatibility problem that people don't understand why you can't do that, one that can’t simply be solved by mirroring components.

A Brief History of How We Got Here

• Back in 2017: I began working on my second sim and hit a critical roadblock—getting the sidewalls to fit the front windows was nearly impossible. This forced me to pause, take a year off, and learn Fusion 360, eventually leading to the full cockpit CAD design to ensure structural integrity and compatibility.

• Early Patreon Days: When I returned to the UK, I didn’t even have space for a full MIP at home. That’s when I pivoted toward designing the single-seat desktop version, which sat on a table. Many of you will recall the early Patreon discussions about switching to a single large monitor—a choice that simplified construction but also meant stepping away from exact cockpit dimensions.

• Design Divergence: As a result, the MIP screen frames were enlarged, moving further away from real aircraft dimensions. Fast forward to 2024, after relocating to a larger space, I converted the single-seat unit into a full standing setup. This evolution into a half-cockpit required numerous adjustments, making nearly every part incompatible with the dual-seat structure.

Key Differences That Make Single-Seat and Dual-Seat Parts Incompatible

To illustrate how much has changed, here’s a breakdown of the major compatibility issues (the following images are of the dual seat windows and sidewall with the single seat MIP and Glarewing- This shows the incompatibility):

The glarewing sits too high and too far aft compared to the original, correctly sized dual-seat unit.

• Sidewalls & Windows:

  • The single-seat front windows differ significantly in size and shape from those of the dual-seat version.

  • The sidewall assembly has been raised by 50mm and shifted aft by 30mm, meaning these components will not align properly if mixed between single-seat and dual-seat builds.

• Glarewing Interference:

  • The single-seat glarewing collides with the dual-seat front windows, disrupting proper placement.

  • Several builders have unknowingly attempted to fit 737SS glarewings onto 737DS cockpits, leading to significant misalignment.

A Frankenstein Build That Doesn’t Work

• Combining parts from both designs results in a third, hybrid cockpit—one that does not fit either shell properly.

• While some highly skilled builders have successfully adapted mismatched components, this approach is not viable for most users.

Why Mirroring the Single-Seat Won’t Solve the Issue

Some have asked: "Can’t we just mirror the single-seat design to create the dual-seat shell?"Unfortunately, it’s not that simple. The issue isn’t just symmetry—it’s how the glarewings meet the sidewall and how the front windows align with the glareshield. Simply mirroring components would lead to a structurally awkward-looking cockpit.

Final Thoughts & Advice Moving Forward

I cannot stress this enough—if you're building the dual-seat version, you must stick to the dual-seat CAD and parts. Using oversized 737SS components and forcing them into a dual-seat setup creates unnecessary headaches that could have been avoided.

To borrow from the famous Ghostbusters quote by Dr. Egon Spengler: "Don't cross the streams."Just as crossing proton streams can lead to catastrophic consequences, mixing single-seat and dual-seat components can result in a cockpit that won’t work.

For those who have already attempted this fusion, my deepest apologies—I thought I had made the incompatibility clear across all platforms, including the webshop. Moving forward, I will ensure that this is communicated even more explicitly to prevent future confusion.

Thank you again to everyone who shared their experiences. Your feedback continues to be an invaluable part of improving this community, and I appreciate every one of you. This post is solely to explain why you can not mix parts unless you can modify the design. I thank everyone for your comments and feedback, good or bad.

Best regards, Karl