Sikorsky S70-C Firehawk (Delayed)

[jwarner]

It seems about time for me to get into the TC15 spirit. I've been building up a storm in my dorm room every chance I've had when I haven't been studying, and it seems about time I share my progress. I noticed that there are notably few helicopters so far, I think just steph's Chinook and Eric's Skycrane. So I decided to join the fray, and I'm going big on this one, the Sikorsky S-70C Firehawk, the cousin of the military Blackhawk. Unlike the blackhawk though, this one comes in pretty colors:

Sikorsky S-70C - N2FH FireHawk by Christopher Ebdon, on Flickr

I want my model to focus on playability, so I plan on making the swashplate RC controlled with PF. I also wanted to use as few motors as possible, so here's what I'm planning:

• 1 L motor - rotor blade rotation
• 1 M motor (or L motor if needed) - swashplate control
• 1 Servo motor - switch between collective, left/right cyclic and forward/backward cyclic

So few motors means that the gearbox is naturally a beast, so it will likely be taking up the entire rear of the helicopter. Waiting on a few more parts to arrive before I share what I've concocted on that front. In the meantime, here's what I've been working on:

Sikorsky S70-C Firehawk - WIP by jwarner1718, on Flickr

I apologize ahead of time for the wild colors and stickers, my selection of panels is pretty slim so I'll be playing 'rainbow warrior' for a while until I have most of the design down. Easier to order everything at once right?

Sikorsky S70-C Firehwak - WIP by jwarner1718, on Flickr

Both cyclic sticks are synchronized using a few linkages. They will not be linked up to the swashplate movement, something I had debated for a long time, but decided that with the route I had taken with the gearbox it just wasn't feasible to fit it in. I guess this makes a fair consolation prize though.

Sikorsky S-70C Firehawk - WIP by jwarner1718, on Flickr 

The battery box sits behind the pilot seats, and the fake collective lever acts as a pin that can be removed to slide it out.

I'm really excited for this contest, hoping to finish in time and that I haven't bitten off more than I can chew. If I don't make it before the contest though I'm definitely finishing this one.

Cheers, Jonathan

Edited December 10, 2018 by jwarner

[garethjellis]

I am excited to see the progress with this model

Edited December 10, 2018 by garethjellis

[Erik Leppen]

Nice, and good start. I like how clean the design looks so far.

At this scale, your model will be huge. I'm not even sure the standard Technic helicopter blades will be large enough.

Looking forward to upcoming progress :)

[1gor]

Sikorsky makes beautiful helicopters, especially for coast guard services; so I expect this one will be beauty. So far model looks really good. Battery placement is in optimal position. 

[jwarner]

1 hour ago, Erik Leppen said:

At this scale, your model will be huge. I'm not even sure the standard Technic helicopter blades will be large enough.

Yes, I am afraid the blades are starting to look too small. Not sure how I'd prefer to go about fixing it but I suppose that can wait until I have a better sense of the size of the completed model.

23 minutes ago, I_Igor said:

Sikorsky makes beautiful helicopters, especially for coast guard services; so I expect this one will be beauty. So far model looks really good. Battery placement is in optimal position. 

Thank you! The coast guard Jayhawk was one of my first picks but I was afraid the color patterns were a bit out of my league.

2 hours ago, garethjellis said:

I am excited to see the progress with this model

Appreciate the enthusiasm!

[1gor]

My favorite are HH52 and S61-R models, but first model that I saw (long ago) were H-19 and H-34...

I like helicopters, specially used like coastal guard, or for mountain rescue services...not to mention in fighting against fire...

I think your version would end how one Sikorsky deserves - as headlight 

[AFOLegofan66]

Great job so far! 

[jwarner]

UPDATE

I got a small order of parts in the mail today and with them I was able to finish the gearbox:

Sikorsky S70-C Firehawk - WIP by jwarner1718, on Flickr

I haven't hooked up any motors yet, but it will use a servo motor on the rear side to switch between collective, left/right cyclic and forward/backward cyclic controls. The gear on the fornt is in lieu of an M motor, which controls the actual adjustment of the swashplate. In all there are 4 driving rings controlled by three of the new orange changeover gears, one each for switching between collective/cyclic, engaging/disengaging the left-right pair, and engaging/disengaging the front-back pair. 

Sikorsky S70-C Firehawk - WIP by jwarner1718, on Flickr

The red switch marks where the servo will attach, and the yellow axle drives the rotor. Also here you can see a couple of these in black on the center cross gear. This is crucial to the function of the gearbox, as it will rotate the neighboring right gear when the servo rotates one way, but not the other, allowing either cyclic pair to engage individually.

Sikorsky S70-C Firehawk - WIP by jwarner1718, on Flickr

The rotorhead uses the turntable piece as swashplate. To keep its rotation aligned with the rotor axle, I used a couple of idler linkage constructions (the beams in black). It keeps both rotating together, but I'm having issues with vibration, particularly during cyclic pitch. If anyone has any advice on how to stabilize the rotor axle I am all ears.

Finally a quick video demonstrating the gearbox in action:

Moving on to bodywork, will keep you guys posted.

[Erik Leppen]

That gearbox unit looks mental

It was of course to be expected that you'd find a similar solution to what I use for my entry, but much more robust and seemingly also better working so far. I especially like your system of "dummy linkages" to align the whole thing. I may borrow that

On the other hand, your unit is huge, so you may want to consider using custom blades (made from beams or so, I mean).

I also see you took the trouble to align all balljoints around the turntable in a single plane, to prevent unwanted sideways movement when the turntable's angle changes.

Looking forward to seeing it combined with your earlier unit. That would give a sense of scale.

[Ox1337]

Wow it is great! Waiting for instructions ;)

[jwarner]

 

17 hours ago, Erik Leppen said:

...

Feel free to borrow whatever helps The balljoints have to back aligned otherwise it puts too much strain on the dummy linkages (I like that term btw) and they won't along with the rotor properly. As for combining it I've gotten it attached to where they hold well enough, but I'm in the process of packing to head home for the holidays so it will likely be a few days before I can get a few more photos.

6 hours ago, Ox1337 said:

Wow it is great! Waiting for instructions ;)

Thank you! My intention was to build the gearbox as a separate unit so anyone could use it if they wish, instructions for the whole helicopter might be beyond me right now though 

[jwarner]

Hello everyone, quick update on the helicopter. I haven't really had any chance to build over winter break so I'm really afraid that I Won't be able to finish this project in time. That being said, I would rather take my time and finish the model properly than try to rush it to meet a deadline. 

Sikorsky S70-C Firehawk MOC - WIP by jwarner1718, on Flickr

As you can see I'm starting to run out of parts due to the sheer size of the model, so the color vomit is starting to set in. Another reason I'm afraid I won't finish, since I'll have to order parts when I'm finished designing, which will probably tack a week or more onto my build time. Here's a minifig for scale, and this is probably just short of half the final length:

Sikorsky S70-C Firehawk MOC - WIP by jwarner1718, on Flickr

I've gotten the gearbox hooked up to the motor and battery box, and I've started moving the bodywork towards the back. The stacks of white 1x4 bricks are placeholders for these in white to mimic the outline of the windows. 

Where I'm really starting to stall is the engines, they're a very weird shape that's hard to replicate. I might have to try a system solution to get something I'm happy with. I'm trying to fight builder fatigue and get back into the swing of things, and I hope I can in time to enter. 

[Bartybum]

Looks amazing, gotta say it definitely blows all the others right out the water so far. I think I'd prefer to see you drop out and actually take the time to properly finish this monster.

[nerdsforprez]

Agreed.  Don't rush it.  Looks great at this point, would hate to see it compromised because of a deadline. 

That being said, many of the competition "deadlines" have ended up being moved back.  Sometimes a week or two, and apparently you are not the only one.  I would not be surprised if this one gets moved as well, so perhaps keep that in mind.  I am sure Jim keeps a good tab on these sort of things. 

[m00se]

My technic skills are to limited to understand how it works, but I do understand that it's amazing!

[ndm1306]

Nice

[jwarner]

Yeah, I'm not gonna make it.

I hit a snag somewhere along the way trying to wrap up the bodywork, and I felt the dreaded builder's block setting in. I really didn't want to force it because I'm never happy with forced work, but I am a little disappointed that I couldn't finish in time. Now that I'm back at university I've got a lot less time too, and there's a lot of other conflicting things that are demanding my attention right now.

So the Firehawk sits on a shelf in my dorm for now, but I'm certainly going to finish it. That's probably the best thing TC15 did for me was to get me started on it, because I was afraid once I finished the gearbox I would never start on any of the bodywork. Now that I'm halfway there's no reason to not finish in due time. Meanwhile, I'll be waiting for inspiration to strike again, and for the "itch" to win me over. Good luck to the rest of you!

Cheers, Jonathan  

[grum64]

It’s sad that time constraints means you’ll not have what you feel is a satisfactory entry for TC15 but it’s best to take your time and have what I know will be an amazing build. I look forward to the time when we can see it completed. Hope all goes well at Uni.

Edited January 13, 2019 by grum64

[Bartybum]

Good call, uni’s more important. A heap of builders have been dropping out this competition lately :o

[Lipko]

The deadline is moved by two weeks (to 17th of February).
I'm have the opposite opinion, I will rush my entry to finish because I won't have any time for the couple of next months at least, so if I don't finish the model probably I never will.

[steph77]

too sad, this was promising.

You speek about difficulties on bodywork job?

Maybe we can help?

Steph.

[jwarner]

8 hours ago, steph77 said:

You speek about difficulties on bodywork job?

Maybe we can help?

Yes, I've had the most trouble with the engine housings since they're a long half-oval sort of shape, very hard to to replicate. I tried a system-built solution but didn't get very far, and the half-shell 3x11 panels are too wide when put together. 

I'm also concerned with paneling the tail but I haven't gotten that far yet so maybe it wont be as hard as I'm thinking.

[steph77]

2 hours ago, jwarner said:

Yes, I've had the most trouble with the engine housings since they're a long half-oval sort of shape, very hard to to replicate. I tried a system-built solution but didn't get very far, and the half-shell 3x11 panels are too wide when put together. 

I'm also concerned with paneling the tail but I haven't gotten that far yet so maybe it wont be as hard as I'm thinking. 

For the tail part i do not use panels usually wich is not a real problem.

For the engine housing the curves and generics lines are more important visualy than a real reproduction of the complete surface. So i would probably work with flex axles who cover a fake or functional engine.

This way you'll put some interest and Something 'to see' in the Inside and give a good justification for a 'light' design in this area. just IMHO

[jwarner]

I really like your suggestions, I guess my biggest worry is that with as complete as the front end is I don't want to skimp on the rear and make it look half-baked. I suppose I can try and open up the front a little to balance things out...

Might have to make some time between classes to try some of these things...