Flite Fest 2017: Bugatti 100P

[willsonman]

FPVology: Since the fuselage was glassed with epoxy, a hot wire would never go through that. In addition, when you use a hot wire it melts away a portion of the foam. This is called "kerf." Since I wanted to use the part removed as a mold for the canopy I had to minimize this kerf as much as possible. Since I had previously hollowed out the fuselage it just made sense to use a hobby knife. First, very careful shallow cuts to penetrate the glass, followed by going all the way through to remove the canopy entirely.

I wrapped up the majority of the cockpit area. More to come when all the paint is done. I needed a back plate and decided to carry the horseshoe shape that will accentuate the instrument panel's shape. As you can see, its a very clean layout that drives focus onto the motor and ESCs separately. There will be a large hole it the back plate to vent air aft. I'll use some screen door material on the back side so that there is some material to visually segregate off the cockpit from the battery compartment. More on that later.


Because I had to... I applied some red paint to the motor compartment. I really wanted to see the contrast and get the full image of how this area will look. Pretty sure this is the final nail in the coffin for how awesome this motor is. You can also see the ply plate that I installed that the balsa ESC tray/cockpit will screw into. There is another far aft.


The new Oleo struts arrived via DHL express. These are called offset oleos for fairly obvious reasons. The wheel is offset from the oleo center line. What you see in the image is a front-view in the retracted position with the airplane inverted. So, the top of the image is the bottom of the airplane. The wing needs a filet on the top and bottom portions. If you go back and look at Post #340, you will see that the previous oleo struts forced the wheel to protrude too far through the wing. Once the wheel axle is trimmed and I do some final fitting, this will be a perfect fit and my landing gear is now a non-issue. The wheel axle will be at the scale position when down so the ground handling on my rough field remains. Perhaps we will see the new gear installed this weekend.


Lastly, more sanding and smoothing of the canopy forms. Not much to show other than spackle and WBPU is doing its job, one layer at a time. The thing any person who pulls their own canopies can tell you is that every minute of preparation of a smooth finish will greatly pay off for a perfect pull. Carl, I am sure, can attest to this.

 

[Joker 53150]

Looking good! For those wondering about the choice in red paint (it does seem like an odd choice), it's because the original has a red interior. Not the most subtle color choice, but not much on this bird is subtle!

 

[willsonman]

Actually, Bob Havens at the EAA museum informed me that the red is not known to be the original cockpit interior color. When they received it, it was the color that had been applied through previous restoration efforts. There is no supporting documentation to indicate what the real color was.

 

[wilmracer]

Documentation or not... I think it looks sexy

Bugatti is/was a French company. Their flag is also red, white, and blue. I could see it being an homage to their home nation. Or it could just be because it was flashy. They were race car builders after all

 

[Joker 53150]

I'll stand by the accuracy of my statement, "the original has a red interior". It may not be the original color, cut it's red now!

It looks like Bob has been a solid resource for you, I'm sure he appreciates your interest in this particular plane.

 

[willsonman]

That is a good point! I had not thought of that. Its a bit misleading with a family history that is Italian but they were very much a French family. Ferrari, Maseratti, Lamborghini... Bugatti? Does not really SOUND like Puegeot, Renault, Citroen... see the problem?

 

[willsonman]

I wrapped up the canopy this weekend. Some minor tweaks and final trimming are in order but lets walk through the process.

First, you want to position your part on the bed to minimize webbing. This usually means a 45 degree offset from the squareness of my bed. Then, make sure it is slightly elevated to pull down around the edges a little.


The plastic is prepped. I use my go-to aluminum tape because it stick like mad. Make sure there is no dust or debris on the plastic as it will melt into the plastic as it is heated. Temperature plays a part here. I started at 250 degrees but in the end, I went up to 300 because of how tall my parts were. I needed the added softness to pull around the parts.


After some rough trimming this is what your are left with. The part is firmly stuck inside but careful pulling makes it pop out. A little bit of the primer stuck to the plastic but a quick wipe with a paper towel and rubbing alcohol took it right off without fogging the plastic and scratching the surface. I'm using PETG here.


With both halves trimmed well I taped them together and did a dry fit. Looks great. I added my canopy glue to the seam and after 24 hours it was still curing. It takes awhile sometimes, especially in the cold and moist winter months here. Just let it dry and the part will be stuck forever.

 

[willsonman]

Moving back to the cockpit area, I cut the vent hole to the battery area to allow more than adequate exit venting. I painted the remainder of the cockpit and moved onto the screen to segregate the areas off. I measured the hole again and made a 1/64 ply plate that was oversized and applied some screen door mesh to it using CA. I trimmed the excess and held the part in position on the back side. A few dribbles of CA and she is stuck in place.

Front view is nice and clean.


Back to show the work done.


With the cockpit tray done it was time to put the ESCs back in and do a final fit with the canopy. This is motivation here.


Another angle.

 

[willsonman]

One more update...

I spent a lot of time carefully working the new landing gear configuration for just one side. The large ply beam was necessary to provide a mounting point as well as carry the load. With the odd angle, there is also some forward tilt so the ply had to be filed to the right angle. A new cross member was added that allows a notch of the beam to slide in underneath. The beam rests on the middle cross member. The inner cross member was cut off withe the dremel and ply was added around it for the aft mounting points. The large gaping hole now needs to be filled with foam and gorilla glue to get it all to carry the load more uniformly. Its fairly extensive surgery but in the end, I think it will hold well. Again, these retracts are rated for 5kg and they are seamless in operation. They show no hesitation lifting the weight of the wheel and oleo with nearly zero slop.


Next step is to perform the same work on the other side so that they match. Then the infill with foam. I'll re-glass the area and while I'm at it I will add the CF tow reinforcement to the nose area. No sense in mixing up two batched of epoxy when one will do and I can knock it all out in an hour.

 

[CaptBill]

Very cool.
What are you using for the canopy plastic?
I'm assuming that after the plastic becomes hot enough ( in the oven?) You place the plastic, still on taped to its own box, over the form, push it down and turn on the vac?

 

[willsonman]

Yes, As stated, I'm using PETG. I forget the thickness. Its about as thick as a 2L soda bottle.

So the procedure is to heat the plastic in the oven until it stops drooping or sagging. That is how you know it is uniformly heated. Using a wooden frame allows you to handle it without burns as it does not heat as quickly as a metal frame. We are talking less than 3-5 minutes in the oven. Prior to removing from the oven, I turn on the shop vacuum that is attached to the box. I quickly remove from the oven and immediately go to the box, center, and press down until the seal is made and the plastic pulls. You can also use a microfiber cloth to press the plastic down around the corners while it cools. You have to keep the cloth moving or it will melt into the plastic. Once cool to the touch (but still warm), you can turn off the vacuum and see what you have. Each piece I had one bad pull. My mold construction is usually good for around 5 pulls before it starts to not be strong enough or the finish is shot.

 

[rockyboy]

Are you just using spray primer as the mold surface, or is there some other magic to get the mold to release consistently?

Thanks!

 

[willsonman]

Yup. Just primer. No special treatment other than a final sanding of 3000 grit.

 

[AkimboGlueGuns]

The cockpit is super awesome looking! Can't wait to see it with the instrument panel.

What is your plan for doing the MASSIVE wing fairings? Spray foam?

 

[SlingShot]

Aft of the throttles is a conduit. It almost looks like air controls. Is it an electrical conduit? Hydraulic?

 

[CaptBill]

Sorry, I must have missed the "as stated" part. Or could be I overlooked PETG because I have had no idea what it is.

Thanks for the explanation of the steps.

 

[willsonman]

Akimbo: Well, given that Sponz is printing the panel... you will be one of the first to see it! Wing fairings will be foam scraps glued in place and carved. I did this before on my Gee Bee Z and it worked quite well. It takes time and patience but does work remarkably well. I will form out the wheel wells first and apply foam around it.

SlingShot: The conduits on the sides of the cockpit in the full-scale are for the drive shafts. Remember that this used TWO motors aft of the cockpit and the drive shafts connected to a planetary gear box just behind the props. One of the remarkable engineering feats of this airplane was use of a very complex hydraulic system that deployed flaps, among other things, at different speeds. In basic modern vernacular, it was the primitive fly-by-wire system that defined what a technical marvel this airplane was. Flaps would auto deploy at lower speeds and the elevator planes were more like elevons. Everything worked in concert to stabilize the airplane at the anticipated 500MPH this airplane was designed for. Keep in mind that this is about on-par with modern day Reno racing with the big dog mustangs, RearBear, and the like.

CaptBill: Middle of post 367 PETG=Polyethylene terephthalate glycol It is a very common plastic. In my world, it is a plastic used in bottles that can store liquids at extreme cold (-80C) without breaking and is very resistant to acid and caustic solutions. It is not as durable as HDPE (High-density polyethylene) but is clear and holds up better under higher heat and ultraviolet radiation. With the glycol modifier, it has a higher melting temperature and handles light in a more similar way to glass.

No update. I'm beat and just did not have motivation to even go in the basement.

 

[abieex]

Thanks so much for forcing some of us to think outside our normal FT box. Although most of what you and Dan are doing is clearly way over my head its interesting to follow along and at least try to understand the basis for your collective decisions. Most of us will never elevate our game to this level of science but I, for one, am thrilled with the exposure to it. Thanks again for all you folks do for our community. I will now crawl back into my foam and hot glue cave and pretend I understand it all!!

 

[willsonman]

LOL! I appreciate your kind words. While we never want to have a situation where we are demeaning folks, it stems from the two of the core FT Es... Educate and Elevate. This is why I've nearly exclusively moved to this community. I've been given so much that I want to share it to educate and elevate others. I'll freely admit that I'm not a terribly entertaining guy. I DO try to comprehensively cover my methods so that they are reproducible by others. I work at a biopharmaceutical company and reproducible science is my job. It's just part of my life. I want to see others succeed when they try. That is my reward. I love seeing folks try new things. Its not about a stunning model that will compete in scale competition. Its about having fun with learning and trying.

 

[SlingShot]

Thanks for the lesson. The whole plane is great and that canopy in particular does in fact look very glass-like.