FTFF 2015 Scratch Build: Sikorsky S-39
- Thread starter willsonman
- Start date
Thanks guys! This was by far my most ambitious project ever, even if I did not put my usual detailing efforts in. The big point was to show how quickly and easily you can build a scale airplane from nothing.
Yellow? No, just happened that way.
Weight: Well, to be honest I did not get a weight from after FTFF. I do plan to put it all on the scale this evening. I suspect she will come in around 5 pounds. Keep in mind that this translates to 14.3 oz./sq.ft.--a SUPER floater. The designer says AUW at 7.5 pounds and that still translates to a very nice 21.3 oz./sq.ft. This really is just a flying kite. It is so light and a real pussycat to fly. She is very predictable to fly and scale flight is nearly effortless. With the rudder now fully functional I can coordinate my turns better. I have no hesitations flying this airplane. Further confidence comes from the power setup. My motor will pull 700W (140W/pound), which is more power than most sport planes and comes close to 3D (150W/pound) This plane would easily fly off 3-400W given the wing loading. I really only fly her at 1/3-1/2 throttle. After that the drag from the pontoons and the struts comes into play and I really do not get any more speed. I do get lots more thrust to get out of hairy situations but those will be few and far between again, due to the wing loading. To further add to this... the designer calls for a .45-.60 size 2-stroke. I am using a .32 size-equivalent electric motor. This is a very efficient airplane.
I do have plans to bring this to FTFF next year. I hope many folks will stop by to talk shop and see her in the air. I'm hoping to work with the flight line coordinators to get some times where the skies are not as busy for this and some of the other larger (and frankly nicer) aircraft that people bring to get some stick time. Bigger does indeed fly better and I've been mostly flying larger planes this year. She is the largest airplane in my hangar right now and also the best flying one.
Yellow? No, just happened that way.
Weight: Well, to be honest I did not get a weight from after FTFF. I do plan to put it all on the scale this evening. I suspect she will come in around 5 pounds. Keep in mind that this translates to 14.3 oz./sq.ft.--a SUPER floater. The designer says AUW at 7.5 pounds and that still translates to a very nice 21.3 oz./sq.ft. This really is just a flying kite. It is so light and a real pussycat to fly. She is very predictable to fly and scale flight is nearly effortless. With the rudder now fully functional I can coordinate my turns better. I have no hesitations flying this airplane. Further confidence comes from the power setup. My motor will pull 700W (140W/pound), which is more power than most sport planes and comes close to 3D (150W/pound) This plane would easily fly off 3-400W given the wing loading. I really only fly her at 1/3-1/2 throttle. After that the drag from the pontoons and the struts comes into play and I really do not get any more speed. I do get lots more thrust to get out of hairy situations but those will be few and far between again, due to the wing loading. To further add to this... the designer calls for a .45-.60 size 2-stroke. I am using a .32 size-equivalent electric motor. This is a very efficient airplane.
I do have plans to bring this to FTFF next year. I hope many folks will stop by to talk shop and see her in the air. I'm hoping to work with the flight line coordinators to get some times where the skies are not as busy for this and some of the other larger (and frankly nicer) aircraft that people bring to get some stick time. Bigger does indeed fly better and I've been mostly flying larger planes this year. She is the largest airplane in my hangar right now and also the best flying one.
We are having our fry and fly on 10 OCT, rain date on the 24th if you want to swing up this way.
Thanks! I may have to do that! I think our fall fun fly is the following weekend so as long as there isn't a conflict I might be able to make it out. I'd love to get some video of her all wrapped up and in the air.
If you've got details on the fly in send them my way.
I doubt I could make it on the 24th... The Air and Space museum does a Halloween event that day and I'll be volunteering with a few other members from our club. We set up displays of RC aircraft and bring in simulators for the kids to use. I've got my fingers crossed that I can get some shots of the warhawk with the full scale "next" to it
Yeah, we'll see. THe forecast is not looking good with the hurricane on the way.
Spastickitten
Senior Member
Just a little wind, it'll be good practice
Had her out tonight. Got some beauty shots and video. I'll process and post it tomorrow. Too tired right now.
Last edited:
gabrielete
New member
:applause::applause::applause::applause::applause::applause::applause::applause::applause:
AMAZING BUILD! congratulations, one of the best of this forum.
AMAZING BUILD! congratulations, one of the best of this forum.
Thanks guys.
I used wire ring terminals soldered in place. The hard points are ply. I carved out a recess in the foam just big enough for the ply pieces and then used gorilla glue to secure them. If you look at some of the earlier pictures and even the maiden flight video you will see those ply hard points.
smithhayward
Large Child
Hey wilsonman, can you tell us the exact type of foam board that is? I see all sorts available at my hardware stores .
The plane is built from Owens Corning insulation foam board that can be purchased at Home Depot (the pink stuff).
http://www.homedepot.com/p/Owens-Co...uared-Edge-Insulation-Sheathing-45W/100320352
http://www.homedepot.com/p/Owens-Co...uared-Edge-Insulation-Sheathing-45W/100320352
Yup! Wings, fuselage and pontoons are from the 2" thick stuff and the tail planes are two layers of foam board.
smithhayward
Large Child
This stinks... HD doesn't carry the 2" thick stuff here (anywhere within 100 miles). We have another product that's 2" thick but it's faced (the pink stuff is unfaced). I doubt the coating peels off easily...
I'll have to continue my search...
I'll have to continue my search...
Similar threads
