Flite Fest 2017: Bugatti 100P
- Thread starter willsonman
- Start date
Take a number. Believe me, I could just shoot blue all over the place and be done with it. That is fine for a sport scale model... This is not that.
hackofalltrades
Rocket Surgeon
Your patience and restraint is to be commended. It will definitely show in your final product.
It usually does pay off but there are times at this stage when you just have to balance yourself and know when to quit. Scale modeling is a matter of knowing to what extent you are willing to go to for fidelity. For me, it is usually an on-the-fly decision when to finally say "I'm done."
I finished up the masking and carefully carried her out to the garage. It was a fairly windy afternoon so doing it in the lawn was not an option. The wind would carry the paint too much and I would get an uneven application of primer.
Overall, I am very pleased. There is minimal work to be done on the bottom side with a bit more on the top. The primer helps to even out the coloring so that you can see the imperfections. Mostly what I will be dealing with is areas where I did not do enough sanding of the WBPU/BP mix. A couple other minor areas may need some additional work but really very minor. Once those are done I can start masking out panel lines and do those. They do not take long, especially with the quick-drying auto primer.
I also took time to polish the axles of the wheels and apply some graphite powder. Anything to reduce the rolling resistance for take-off will be helpful for a more forward CG.
I finished up the masking and carefully carried her out to the garage. It was a fairly windy afternoon so doing it in the lawn was not an option. The wind would carry the paint too much and I would get an uneven application of primer.
Overall, I am very pleased. There is minimal work to be done on the bottom side with a bit more on the top. The primer helps to even out the coloring so that you can see the imperfections. Mostly what I will be dealing with is areas where I did not do enough sanding of the WBPU/BP mix. A couple other minor areas may need some additional work but really very minor. Once those are done I can start masking out panel lines and do those. They do not take long, especially with the quick-drying auto primer.
I also took time to polish the axles of the wheels and apply some graphite powder. Anything to reduce the rolling resistance for take-off will be helpful for a more forward CG.
Last edited:
TexMechsRobot
Posted a thousand or more times
Polyurethane.
Water Based PolyUrethane
TexMechsRobot
Posted a thousand or more times
I totally misread that....
I thought he said he understood the WB part. Thanks for picking up my slack willsonman!
I thought he said he understood the WB part. Thanks for picking up my slack willsonman!
You got it.
I took the airplane outside yesterday and it was a nice day too! A little wind and it was manageable so I took her out to the deck to do the sanding. Since I knew this would be a terrible mess, it was a good move. My wife even came out to talk with me while I worked! At any rate. The BIG sanding job is now over. The majority of the work is done and everything from here on out is details.
Here is a shot of the sanding in-progress. I highly recommend doing this outside for one other point: Sunlight. The sun really brings out the imperfections and allows you to see them more clearly.
And the bottom in the sunlight, post-sanding and another coat of primer.
And the top, same as the bottom.
Here is a shot of the sanding in-progress. I highly recommend doing this outside for one other point: Sunlight. The sun really brings out the imperfections and allows you to see them more clearly.
And the bottom in the sunlight, post-sanding and another coat of primer.
And the top, same as the bottom.
Got another sanding session in yesterday and we are ready for panel lines! I had not done any real observation of panel lines yet so I went to the old google machine and it spat out a lot of pictures and they all indicate one thing... This airplane is made of wood. There are very few panel lines to speak of. There are metal fairings that are riveted or screwed on in strategic places but it does not amount to very much. All at the wing/stabilizer roots. So it should not take long to get them done along with the rivet markings.
I tested out my semi-gloss clear coat spray and it is the look I am really going for. I used it on the servo covers and it should seal the paint well as well as protect from UV so the paint should not fade as quickly. Latex paints inherently are not UV stable so this is a good thing. I plan to keep here well-shaded as any heat build up on the foam will cause bubbles in the finish. This comes from off-gassing.
Once I have the final paint and clear coat on I can start to address the last two items. They are the final prop setup and the oleo covers. The front prop will either be a 8x6 or 9x7.5 cut to 8x7.5. RPM data should give me a good indicator of loading. The idea is to try and stabilize the RPM load for the "right" sound and even power loading on the motors. I acknowledge that I may lose some speed here but I'm not terribly worried about that.
The oleo covers will be a fun job. More glass work ahead. I will retract the gear and cover it with card stock. Then I'll apply saran wrap and apply glass over where the hole would be. This will get the glass to cure out with any twist or compound curve "baked in" to the glass. Trim, hinge, paint, and fit. I'll design and 3D print a mount that will go on the strut. This piece will freely move along the axis of the strut when retracting. The cover will be permanently affixed to hold it down and allow it to freely move during movement.
Hope to have panel lines and rivet marks done this week to have a blue paint session this weekend.
I tested out my semi-gloss clear coat spray and it is the look I am really going for. I used it on the servo covers and it should seal the paint well as well as protect from UV so the paint should not fade as quickly. Latex paints inherently are not UV stable so this is a good thing. I plan to keep here well-shaded as any heat build up on the foam will cause bubbles in the finish. This comes from off-gassing.
Once I have the final paint and clear coat on I can start to address the last two items. They are the final prop setup and the oleo covers. The front prop will either be a 8x6 or 9x7.5 cut to 8x7.5. RPM data should give me a good indicator of loading. The idea is to try and stabilize the RPM load for the "right" sound and even power loading on the motors. I acknowledge that I may lose some speed here but I'm not terribly worried about that.
The oleo covers will be a fun job. More glass work ahead. I will retract the gear and cover it with card stock. Then I'll apply saran wrap and apply glass over where the hole would be. This will get the glass to cure out with any twist or compound curve "baked in" to the glass. Trim, hinge, paint, and fit. I'll design and 3D print a mount that will go on the strut. This piece will freely move along the axis of the strut when retracting. The cover will be permanently affixed to hold it down and allow it to freely move during movement.
Hope to have panel lines and rivet marks done this week to have a blue paint session this weekend.
CrossedUpChris
Member
Sounds exiting!
It is, and frankly I'm ready for this project to be done.
As a fun and minor distraction, I am seeing if I can get my Goon back together to bring to FF. She had a bad tumble on her last bungee launch. Slow-motion footage, captured by Carl, revealed that the left H-stab slipped off the rail inducing a left roll on launch. The airplane went full-speed into a run-up stand and nearly took our my Club president's IMAC airplane (50cc gasser). I've got the fuselage cracks glued back together and the motor re-installed. The Elevators need to be completely re-built and I'm doing that in balsa as I have quite a bit of scrap on-hand. The foam ones just took so much beating that It felt prudent to do so. 1800kv motor and I have a 7x6 prop on-hand. On a 4S battery she should cook fairly well. My club members have been getting a workout hand-tossing the E-flite RearBear so I'm hopeful that I may be able to get a good hand toss to avoid the launch rail on the bungee system. If I get a good test flight in I will slap some paint on her and call it good.
As a fun and minor distraction, I am seeing if I can get my Goon back together to bring to FF. She had a bad tumble on her last bungee launch. Slow-motion footage, captured by Carl, revealed that the left H-stab slipped off the rail inducing a left roll on launch. The airplane went full-speed into a run-up stand and nearly took our my Club president's IMAC airplane (50cc gasser). I've got the fuselage cracks glued back together and the motor re-installed. The Elevators need to be completely re-built and I'm doing that in balsa as I have quite a bit of scrap on-hand. The foam ones just took so much beating that It felt prudent to do so. 1800kv motor and I have a 7x6 prop on-hand. On a 4S battery she should cook fairly well. My club members have been getting a workout hand-tossing the E-flite RearBear so I'm hopeful that I may be able to get a good hand toss to avoid the launch rail on the bungee system. If I get a good test flight in I will slap some paint on her and call it good.
Upon masking off my panels yesterday I made a great discovery, so lets get to it.
In the world of aviation there are three main ways of doing panels, as illustrated below. The first way is a simple butt joint. Two panels are butted together and riveted to the substructure. This has lower drag but increases weight as rivets are needed on both panels. The second way is panel overlap, where the panels are overlapped and single lines of rivets are used to secure them. This reduces weight but increases drag from the irregular surface. Both of these ways have their advantages and can be used in strategic ways for mass-produced aircraft. The THIRD way incorporates tooling and metal work to create a lip where there is panel overlap but the panels are butted to reduce drag AND weight. It is more complex and requires more machine work and is something that war-time aircraft may not have used due to ease of repair in the field and speed/cost of manufacture.
I made this realization while observing the following picture. The rivets are along the trailing edge and there is a single line of rivets showing that there is panel overlap. What did not make sense was that if there was panel overlap there the drag from the top panel would create a lip that would create more drag than if the fore panel was over top of the aft panel. Also note the slight gap at the "T" junction in the middle left of the image. This was the key indicator to me that what we are seeing is a lipped overlap.
I wanted to be sure that this method was used all around the panels and this image showed me the complexity of wood and metal construction that this aircraft faced. You can see that the fairings for the empennage are just overlapped and do not incorporate a machined lip. This is because the stabilizers are wood and the fairings are metal. So, in this area there is a simple overlap and a different modeling technique must be used.
In the world of aviation there are three main ways of doing panels, as illustrated below. The first way is a simple butt joint. Two panels are butted together and riveted to the substructure. This has lower drag but increases weight as rivets are needed on both panels. The second way is panel overlap, where the panels are overlapped and single lines of rivets are used to secure them. This reduces weight but increases drag from the irregular surface. Both of these ways have their advantages and can be used in strategic ways for mass-produced aircraft. The THIRD way incorporates tooling and metal work to create a lip where there is panel overlap but the panels are butted to reduce drag AND weight. It is more complex and requires more machine work and is something that war-time aircraft may not have used due to ease of repair in the field and speed/cost of manufacture.
I made this realization while observing the following picture. The rivets are along the trailing edge and there is a single line of rivets showing that there is panel overlap. What did not make sense was that if there was panel overlap there the drag from the top panel would create a lip that would create more drag than if the fore panel was over top of the aft panel. Also note the slight gap at the "T" junction in the middle left of the image. This was the key indicator to me that what we are seeing is a lipped overlap.
I wanted to be sure that this method was used all around the panels and this image showed me the complexity of wood and metal construction that this aircraft faced. You can see that the fairings for the empennage are just overlapped and do not incorporate a machined lip. This is because the stabilizers are wood and the fairings are metal. So, in this area there is a simple overlap and a different modeling technique must be used.
Empowered with knowledge, I started to work on masking out the panel lines.
First up were the filet lines. These were straight forward. I'm using 1/64" Chart Pak tape. It is a vinyl tape with adhesive on it. DO NOT buy an off brand. When you go to remove it, the off brand is a nightmare. The tape will be painted over with primer using 3 light coats and when removed will leave a shallow groove to simulate the slight dip in the surface between panels.
Here is the bottom with the lines as well as the bottom of the empennage.
The empennage uses the overlap technique so just masking off with tape is all that is required.
First up were the filet lines. These were straight forward. I'm using 1/64" Chart Pak tape. It is a vinyl tape with adhesive on it. DO NOT buy an off brand. When you go to remove it, the off brand is a nightmare. The tape will be painted over with primer using 3 light coats and when removed will leave a shallow groove to simulate the slight dip in the surface between panels.
Here is the bottom with the lines as well as the bottom of the empennage.
The empennage uses the overlap technique so just masking off with tape is all that is required.
The primer was first applied to the empennage portions so that overspray from the filet would not create lines from the masking of the empennage. Once that was done, I sanded back the joint between the surface and the tape to where I could see the tape and removed the tape to reveal a subtle panel overlap.
Then I did the same for the filet lines. 3 light layers but it was still not cured enough to sand and remove the tape. I left this to cure out overnight.
Between paint applications I quickly modeled the oleo cover support. 3 test prints got me to the right inner diameter to be lose enough to slide but not too much slop. Fusion 360 made this modeling a snap. Just 4 polygons and adjusted the inner diameter to get it right. Once the struts go back on I will verify that there is enough clearance between the strut and the well when retracted. So, a further round of refinement may be needed but it will be a quick fix.
So tonight will be time to pull off the panel line tape, the control surface masking and start doing some rivets. This is great progress and may get some blue on here sooner than I thought.
Then I did the same for the filet lines. 3 light layers but it was still not cured enough to sand and remove the tape. I left this to cure out overnight.
Between paint applications I quickly modeled the oleo cover support. 3 test prints got me to the right inner diameter to be lose enough to slide but not too much slop. Fusion 360 made this modeling a snap. Just 4 polygons and adjusted the inner diameter to get it right. Once the struts go back on I will verify that there is enough clearance between the strut and the well when retracted. So, a further round of refinement may be needed but it will be a quick fix.
So tonight will be time to pull off the panel line tape, the control surface masking and start doing some rivets. This is great progress and may get some blue on here sooner than I thought.
Thanks! I've always enjoyed the learning aspect of this hobby. It always makes me smile when others get something out of what I do. Thanks for making my day!
hackofalltrades
Rocket Surgeon
I second quimney. I wish I could see your builds in person to truly appreciate the amount of attention to detail you put into them.
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