Actually Catching Up
Welcome back! Now its time for actually catching you up with our projects. We have been busy on three main fronts: the LiteFighter tail structure and load test, the B-17 tail structure and then the facilities upgrades needed to do all of it.
The P-40 tail is done, but we are working on the aft fuselage box frame that will be tested together with the horizontal and vertical stabilizers at the same time. We already have the fixture from previous testing of the prototype fuselage. The aft fuselage box will go together very rapidly and we will be testing shortly. Will post videos and pics. The FEA computations show we are fine, it will be interesting to see how close the software comes to reality. The B-17 tail spars, ribs and skins are being fabricated and then will go into our new universal vertical build fixture at our build studio. The facility upgrades included several wiring and lighting tasks, adding a ceiling fan to the shop, additional receptacle boxes and conduits along the shop walls for future work cells. We then designed, fabricated and installed our universal build fixture.
The P-40 tail components went together well. Had some minor fitment issues with our vertical. As a load test, we were fine with that and also didn’t spend a lot of time to make it beautiful and impressive - we are just going to bend it under loads. Fixing the dimensions was an easy fix in cad. Speaking of cad (Computer Aided Design), we modeled the LiteFighters in AutoDesk Inventor. Its an old version we have a valid license and know the program. The B-17 project is being designed in AutoDesk Fusion (Fusion 360). Its similar to Inventor and SolidWorks and we are transitioning very quickly. The FEA simulation environment is very easy to learn and powerful. We transferred a 3D model of the P-40 fuselage structure into Fusion to run the simulation. Passed with “flying colors”. We could even lighten it up some more, but we want to make sure we are not losing rigidity. One thing you notice when flying our plane is it feels Solid. I really like that. We will likely transition the entire LiteFighter design into Fusion at some point. Each CAD software package has its strengths and quirks. Fusion seems solid and is working for us. Other kit aircraft companies are using Fusion now. Its also very economical to purchase seats compared to SolidWorks and Inventor. A primary goal with the Beta airframes is to optimize (lighten) the structure to improve performance. So far so good!
We work the P-40 effort as we always have, nights and weekends. Our day job is the bomber project until we start bringing income in for the LiteFighter Beta and then standard kits. That should be quite soon, once the testing confirms our structure. We will then add to the crew as needed to get it all done. Realizing the pressure, we added Nathan Watrous to the full time crew for the bomber. He has been volunteering all-along when possible. Working out great, like us, he is wearing many hats! Design, fabrication, assembly and facility construction, etc…
The B-17 bomber project is just getting rolling with a lot of facility improvements required to handle such a large project. The design of primary structure is pretty well along - to where we can fabricate the entire back half of the aircraft. We are starting with the horizontal stabilizers and the vertical stabilizer right after. Then the elevators and the rudder. We will hang those up on our shop wall - that will get them out of the way and man, that will look impressive! Our preliminary weight and balance calculations and 3D modeling is showing we are a little heavy with the cg in the zone - not unexpected. We have been rounding up typically for all components for conservative guesses. We are optimizing structure as we go and will be working to reduce weight as much as possible. Aaron is crunching numbers - even on vacation!
The 60% B-17 airframe is pretty damn big! Wingspan is 62 feet, length is 38 ft. Fuselage is 50 inches in diameter with a dog house on top. The span of each horizontal stab is 11.6 ft. How to build such a large airplane? Our plan is to build it in short sections of 20 ft or less. We will ultimately need a large space to assemble all the pieces into the whole. That is down the road a bit. For now, we will use our build studio (my garage) and our new universal build fixture. We studied Steve Wolf’s P-47 wing build fixture and picked his brain. He is such a tremendous wealth of knowledge for fabrication! He built both wings at the same time and it saves time doing that. Our fixture is based on his, but made for adjustability to make the other parts of the plane. This fixture can adapt to different sized aero structures and allows two wings or horizontals to be built at the same time. Additionally, it can also hold different jobs at the same time or support a fuselage section build. Its made with Unistrut channels at top and bottom that allow the 8020 vertical t-slot columns to adjust horizontally to support structures properly. Then brackets reach out from the 8020 columns to grab the structures as needed. All of this can be adjusted vertically and horizontally. So we can build Bomber components now, and LiteFighter or other wings and parts later.
UPDATE: Good news: we have cut first parts and forming blocks on the B-17 build. They are big! The horizontal stab is as big as our LiteFighter main wing!
Bad news: Windows update killed our access to our network access storage (NAS) devices. Those older devices (Drobo) are no longer supported. We couldn’t just revert to the previous update because it would require remapping and that would risk loosing all access to the old devices. Soo, we had to buy a new NAS device with cloud backup. We had an old Windows pc running our old CNC router that can still see the Drobo units. So we could transfer the data by using an external solid state drive and haven’t lost anything. But it was dangerous! So, if you have important data, keep it on current devices. I’ve been unable to get to some of our data for over a week. This delayed me posting this blog update. We have old backups of the design data that we could access, but would loose some recent design effort on the LiteFighter and some non-design files we need. fortunately, the Fusion cad files are all stored in the cloud and were available.
Will post more pics and updates as we get going. Thanks for folllowing!
