FTFF 2015 Scratch Build: Sikorsky S-39
- Thread starter willsonman
- Start date
Wow! Them's some big decals.
So running through the numbers...
4500mAh 4S1P battery
60A ESC
770Kv motor
Max prop diameter is 12 inches. Since this will be fairly light for the wing area I'm not too worried about speed... but there is a lot of drag on this plane from all the struts. A 12x8 prop seems to be the sweet spot here. It should give me about 34oz of thrust and a speed around 45 MPH. If I go to a 12x6 I get a few more oz of thrust but take a hit in the speed department. The best part is that the motor can handle up to 700W and I'll be barely scratching 300W static. This should be a very efficient setup. I estimate an RPM of 5500 so it should be very quiet and more scale. The scale engine ran at 2000RPM but my lower RPM will be better than the typical electrics that sound like mosquitoes. Since I am not pushing the current on this plane I will not apply large bullet connectors for the battery. I'll stick with XT-60s.
... Flight time? LOL at WOT I'm looking at over 13 minutes. With the light wing loading I'm thinking I could easily do 20 but it depends on the drag I get.
4500mAh 4S1P battery
60A ESC
770Kv motor
Max prop diameter is 12 inches. Since this will be fairly light for the wing area I'm not too worried about speed... but there is a lot of drag on this plane from all the struts. A 12x8 prop seems to be the sweet spot here. It should give me about 34oz of thrust and a speed around 45 MPH. If I go to a 12x6 I get a few more oz of thrust but take a hit in the speed department. The best part is that the motor can handle up to 700W and I'll be barely scratching 300W static. This should be a very efficient setup. I estimate an RPM of 5500 so it should be very quiet and more scale. The scale engine ran at 2000RPM but my lower RPM will be better than the typical electrics that sound like mosquitoes. Since I am not pushing the current on this plane I will not apply large bullet connectors for the battery. I'll stick with XT-60s.
... Flight time? LOL at WOT I'm looking at over 13 minutes. With the light wing loading I'm thinking I could easily do 20 but it depends on the drag I get.
INVENTORY!!! The first of many. I found the carbon tubes I was looking for to do the wing joints so I am set there.
I ordered the new Master Airscrew Electric props. Should look a little better than an APC-E prop, and I really wanted to try them out. Ordered two... always have a backup, always.
Checked fits of things and I goofed up. I assumed that the mounting plate for the motor was the same thickness as the larger size that I had out on the bench, if not thinner. I was wrong. It is in fact thicker. So I will put that on my Home Depot list. I wanted 6-32 bolts but I do not think they usually stock them at my store. If I have to ream out holes in the back plate, no biggie.
So whats left to buy?
Foam
White Primer (rattle can)
Yellow Paint (rattle can)
Two Receivers... unless I can scavenge ones from my shop somewhere
At least two fresh bottles of Gorilla Glue
Review inventory of glass cloth to see if what I have is sufficient. Off the top of my head it is but I need to check for sure.
If you see something that I've left out... LET ME KNOW!!!!
I ordered the new Master Airscrew Electric props. Should look a little better than an APC-E prop, and I really wanted to try them out. Ordered two... always have a backup, always.
Checked fits of things and I goofed up. I assumed that the mounting plate for the motor was the same thickness as the larger size that I had out on the bench, if not thinner. I was wrong. It is in fact thicker. So I will put that on my Home Depot list. I wanted 6-32 bolts but I do not think they usually stock them at my store. If I have to ream out holes in the back plate, no biggie.
So whats left to buy?
Foam
White Primer (rattle can)
Yellow Paint (rattle can)
Two Receivers... unless I can scavenge ones from my shop somewhere
At least two fresh bottles of Gorilla Glue
Review inventory of glass cloth to see if what I have is sufficient. Off the top of my head it is but I need to check for sure.
If you see something that I've left out... LET ME KNOW!!!!
Attachments
That has got to be one of the nicest things anyone could say about this project. Thank you so much! The overall goal of this build is to demonstrate new techniques and show the benefits to composite construction in relation to speed of build and level of detail. When most seasoned modelers hear "foam airplane" they do not necessarily think about a large airplane with scale details and built to scale.
My sincere hope is that I can get more people excited about trying new techniques that are not difficult to learn and make something truly beautiful that can be flown.
My sincere hope is that I can get more people excited about trying new techniques that are not difficult to learn and make something truly beautiful that can be flown.
Ain't that the truth
I completely agree. I love the Flite Test stuff for its ability to get new people into the hobby and excited about RC and think the Flite Test crowd will be VERY open to learning tricks and tips to build more scale and detailed aircraft.
But one lesson they wont learn there is the prep work you've put into planning out this build. By having a clear plan and having all the parts and materials on hand you can make a big build like this go much smoother and faster. Its particularly important if you're not building from well documented kit. I wish I'd put half of this planning into a few of my bigger builds. It's fun to just start cutting and assembling the big pieces and see an airplane start coming together, but you can really lose momentum when you have to stop building to order parts to solve a problem you didn't anticipate.
Exactly why I'm documenting the preparation here. I suppose I should put together a large poster for my table and have a QR code for this thread.
I did a fairly extensive cleanout of the garage this weekend. In addition to home projects and cleaning I was able to take a bit of an inventory of supplies I am needing from the hardware store.
Gorilla glue
Paints
cutting blades
foam (obvious)
aluminum ducting tape (current roll is getting low)
I also took time to go through a total of 4 large boxes of computer supplies and managed to chop it down to two smaller boxes. In the mess I managed to find allen bolts that fit my T-nuts that are long enough to go through my thicker-than-expected motor mount. I used to be huge into case modding and water cooling/overclocking. Not so much anymore. It was theraputic to shovel it out and make mroe room for airplane junk
I made sure the TWO sets of plans were with the rest of my supplies and checked on my inventory of possible measuring equipment. I know its all there now. My dremel is also in good order and I need to think through if I will need any additional cutting wheels. I have a few ceramic blades and a couple of diamond blades so I think I'm set.
Props should be arriving today.
Gorilla glue
Paints
cutting blades
foam (obvious)
aluminum ducting tape (current roll is getting low)
I also took time to go through a total of 4 large boxes of computer supplies and managed to chop it down to two smaller boxes. In the mess I managed to find allen bolts that fit my T-nuts that are long enough to go through my thicker-than-expected motor mount. I used to be huge into case modding and water cooling/overclocking. Not so much anymore. It was theraputic to shovel it out and make mroe room for airplane junk
I made sure the TWO sets of plans were with the rest of my supplies and checked on my inventory of possible measuring equipment. I know its all there now. My dremel is also in good order and I need to think through if I will need any additional cutting wheels. I have a few ceramic blades and a couple of diamond blades so I think I'm set.
Props should be arriving today.
Looks cool. It is a really good idea and may help keep you from needing to explain yourself to everyone who wonders what on earth you're up to.
If you're doing the poster in color I'd swap out one of the black and white shots with one of the full color renderings of the shell scheme. You posted one earlier in the thread and something like that would be perfect.
Not a big deal at all though. Really looking forward to Flite Fest. There is going to be so much to see!
If you're doing the poster in color I'd swap out one of the black and white shots with one of the full color renderings of the shell scheme. You posted one earlier in the thread and something like that would be perfect.
Not a big deal at all though. Really looking forward to Flite Fest. There is going to be so much to see!
Yeah, I thought about putting renders up from RealFlight but there is a certain element of ... "come back and see what it looks like later." I do want people to come back. Not just come by once.
So my props did arrive yesterday. This is the first time I have purchased the MA electric props. My first impressions are very good. The centering rings are applied to the front of the prop, which is different than the APC-style. I can see that it really is a play on the MA existing tech. The blades are the typical glass reinforced material, which is very strong. The blades do have a bit of undercamber to make them more efficient for electric applications, which makes them thinner and lighter than traditional "classic" MA props. I have a couple of the classic props in 10" varieties and they have more heft to them. The blades are also wider, which I like. It gives a more scale appearance for the traditional Hamilton Standard look. How it performs (balance, thrust, sound, etc.) will determine if I use them more often.
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So, I'm glad I am doing all of this preparation now. I received word that for three... yes THREE... weeks in June (starting on the 8th) I will be out of town for work. After that, I will essentially have one week to pack it all in and head to OH. For those who have followed my build threads, during these weeks where I am offsite I am basically a ghost. I rot in a hotel at nights and work crazy hours to get the work done. So with that... you have been warned. I'm not dead, I just have crappy hotel WiFi.
I will be focusing on cleaning more of the shop and packing up my tools from this point on. I need it to be organized so that I can tetris is all into my car for the trip. I have a roof bag for my station wagon but that, I suspect, will be mostly camping gear. I know, I know, these are the kinds of logistical concerns that you are VERY interested in(sarcasm noted here). I just want to emphasize the planning involved of the project with my home life.
I will be focusing on cleaning more of the shop and packing up my tools from this point on. I need it to be organized so that I can tetris is all into my car for the trip. I have a roof bag for my station wagon but that, I suspect, will be mostly camping gear. I know, I know, these are the kinds of logistical concerns that you are VERY interested in(sarcasm noted here). I just want to emphasize the planning involved of the project with my home life.
Checking off even more. Installed a new exterior door for my basement today. Had to pick up a few things at the Home Depot so I tacked on the things I needed for the build. Extra blades, paints, glue... All set. I've done some extensive clean-up in the shop and I think I'm in a good place now. I actually know where all my tools are now. Things are more organized. And more is ready to just pitch into the car.
I realized that I would never be motivated enough to find receivers. So I ordered them late last night. Using lemon Rx DSM2.
So last night I looked into live streaming bits of this. I think I may be up for doing some update streams. Maybe I would be better off just directly uploading to my youtube channel? What do you all think?
While the idea of live streaming is cool I don't think I'd worry about it, and if you DID decide to do it I would make sure you have the caveat that if anything breaks on the live stream you won't be stopping the build to address it.
I think your idea of the time-lapse video is perfect, and maybe a compilation of quick updates as the build goes along. I picture something like Adam Savage's "One Day Builds" from the TESTED channel on Youtube.
There was some mention of a possible live stream for the event over all. If so I think it would be cool if they checked in with you from time to time. I don't think you're going to want to be responsible for the stream though
