Bernard HV40 - Schneider Trophy racing seaplane scratch build
Time for another scratch build. I can't seem to get away from the Golden Era of aviation and most of the Schneider Trophy planes seem really cool to me. As I was surfing this site: http://doz.jp/sr/h_ozawa_works_2009.html
I came across the beautiful aviation artwork of Mr. Ozawa in Japan. The Bernard HV40 caught my eye with its oddball faired radial, and I knew I had to try and build one. It was really hard to find much information about the plane, so I contacted Mr. Ozawa and he graciously provided a 3-view and some other reference information he had found about the plane.
I have been slowly working on it for a few months now but our computer decided to go on sabbatical for a while. So now that the computer is back up and running, I have a backlog of photos to share.
I wanted to keep it parkflyer-ish, so the wing-span is about 40”. The airfoil is a Clark Y, mostly because they are easy to build, and float well enough for my limited pilot skills to keep up. Other than that, most specs are still up in the air (pun), based on the weight. I am targeting somewhere in the low 20oz. range (I hope). I decided that I am going to full sheet/plank this one, so I am a little worried about how the weight is going to work out.
Here is the picture progress so far.
Beautiful subject with beautiful lines.
Roy Tassell had finished a beautiful model of a similar Bernard HV220 seaplane, started by a friend who had passed away. Sadly Roy has passed away this past year, and was an excellent seaplane modeler. I was fortunate to meet him on SeawingsUK a few years ago. http://theflyingboatforum.forumlaunc...php?f=87&t=828
So its been a while. Here is the latest progress.
Basically, most of the parts have been framed out. I still need to work on the nose of the fuse and the motor mounting. Everything was looking to be pretty light until I started sheeting. The floats doubled (!) in weight from about 30g per side to 60g per side (1/32" sheeting). This is without glassing yet. I had really hoped to sheet/glass the rest of the plane but this weight increase has got me worried. I am planning on using 1/2 oz glass cloth but I still see the weight going way up. I am going to try glassing the floats first (basically because I have to in order to seal them up for bouyancy anyway) and see where they end up. This thing may just sink to the bottom of the lake!
Slowly working on completing the floats. They are almost like building 2 additional airplanes!
Here's the story on weight for 1 float:
Float in the "bones": 31grams (see pics)
Float sheeted: 61grams
Fiberglassed w/ 0.5oz fabric: 87 grams
Based on these numbers, I need to figure out what I am going to do for the rest of the plan regarding covering - Should I sheet/glass or use covering?
This is my first experience with fiberglassing and I have to say it is going better than I expected. There is still lots of sanding/filling/priming to do but the finish is much better than I imagined.
Sorry I have been building, not blogging. Here is the latest.
I decided to go ahead and sheet/glass everything despite the weight. Looks like it will now be a hefty pig somewhere in the upper 20's ounces.
I sheeted most of the fuse, knowing that the fuse was crooked by a few millimeters along the back half. I guess I had hoped I could "pull" it back with the sheeting but, that didn't work, so... "off with its tail"! I spent some more time jigging the whole rear half to the build bench and had much better results the second time around.
With the fuse sheeted, I finally had enough parts to take a rough look where the CG would fall. My original thought was to put everything as far forward as I could get but I should have thought more about the floats, and how much weight they would put forward of the CG. (I am beginning to hate these floats...). After the first CG check, I found that was way off and I needed to move weight backwards. So...more cut and paste. The servos for the rudder and elevator have moved to the back of the belly pan, which works out better for weight and wire routing. The battery moves from right behind the firewall to the belly pan, right about at the CG. I have a few more details to work out but I think it will all finally work.
It is starting to look more and more like a real plane.
Worked on the float struts and fairings. I decided to invest in making a set of jigs out of blue foam in order to keep the fuse and floats aligned while bending up the wire for the struts. It only took a little bit of time and probably saved me time in the long run. It was really easy to bend, check, bend again, etc... and keep everything straight.
The struts are a wire frame (I forget the wire diameter) with foam to make the shape. Once out of the jig, I found the floats are a little heavy for the wire, and they tend to sag in-board under the weight. That changes my strategy for the float bracing wires. I orignally planned on having them for aesthetics only but I think they will need to be structural to keep things solid. Looks like I have some "open float" surgery in my future...
As I mentioned in my last post, I needed to do some surgery on the floats in order to add some strength to make the float wires structural. After some hacking, I got all the wires (0.080 carbon rod) in and it made a huge difference in the stability/strength of the floats, even without glueing them in place.
she's a beauty for sure!!! your doing a great job to the whole project and i'm shocked i never posted before this to thankyou for sharing this build with us. i'v been following along but now i'm subscribed.
i really like the round fuse,all the kits i build are flat sided for the most part and i want to p/u a rounded bipe fuse build in the future.....seems building is taking a back seat to lazyness. thats the drawback of having a job i love and giving it my all during the week.
i like the 1/4 scale newport from balsa usa...
narrow is the place to land...wide is the space to crash....choose the narrow way!
Here's the latest. Basically I have been doing a lot of fiberglassing, sanding, filling, sanding, priming, sanding, sanding, sanding.... I really don't know how guys can stand doing a 1/4 scale with fiberglass. I am glad I stuck with a ~40" span! Most of the major parts are now glassed and sanded but there is still so much to do.
Looking good so far. The fairings are the defining feature of the plane, I don't envy you the work and skill it will take to get them just right. Are you going to pre-finish them before you glue them on?
pmullen - you're right. The plan is to pre-finish the fairings and then glue them on. It would be really difficult to glue them on and then glass/sand/fill them. I am currently part way through glassing all the fairings. After that, I will hollow them out to save weight. I hope that I can glue them in place and only use a small fillet of microballons / epoxy where they meet the fuse. Everything will get a final sand/fill once it is all glued in place, in preparation for final paint.
I also need to integrate the fairings with the motor cooling somehow. The original plane had small holes in the fairings to provide some cooling to the radial engine. I am going to try and use these holes to help cool the motor.
Perhaps this is a little late but it may help you do the cylinder heads. See this post on making cheap silicone casts using silicone caulk and cornstarch as a catalyst. Below is a dummy radial I made from a 1/12 scale Williams Brothers kit. I bought a single cylinder and crankcase kit and used them to make the molds, then cast the crankcase and 9 cylinders with epoxy. The detail was very good. If the foam fairings aren't up to snuff, you could also do the fairings this way too.
Been a while. The plane has been sitting on the bench, with not much happening to it. I have been working on all the details for the fairings, etc. so it looks like really slow progress.
I permanently mounted the wing to the fuse and faired the wing into the fuse with blue foam.
In the last update, I had made all the engine fairings by blue foam. After fitting some of them I realized that the shape was right, and modifying the blue foam was really going to be a pain. I had some mild success with heat stretching a canopy/windshield, so I invested some time and went the vacuum forming route for the fairings. Getting the vacuum forming pattern right took me 4 and 1/2 tries but I finally was happy with it. I started cranking them out and I am now glad that I went the vacuum forming route. I am now in the process of trimming them to fit each location.
In parallel with that, I was inspired by pmullen's suggestion and started working on some ideas for the cylinder heads, but more on that later.