1:9 Scale B-17G - 'Sweet Pea'

wilmracer

I build things that fly (sometimes)
Mentor
I don't have an FT radial but if I got one I'd start with a setup that pulls around 1.2KW on 6s, then see how warm it gets. This is the same size motor as the Tacon Bigfoot 60, it just has a bit more KV so it should handle a few more watts.

My gestimation numbers say that on 6s the 16" 3 blades will be dangerous and the 15" 3 blades will be borderline on the high end.


We'll have to see. I'll definitely test the 16", and likely test it cut down to 15 and maybe even 14". As for the 15x7x3 I'm thinking that right out of the box it may be just fine (although top end speed may be a bit lacking)

Below is chart that @willsonman did when he tested an early version of the motor. the 13x8x3 really didn't draw that much in terms o amps. About 1500ish with a theoretical top end in the mid 70s. The 15x10 still had some overhead in terms of Amps (and of course this was static). Cutting it to 14.5x10, with the extra blade, might put it in a sweet spot, but we'll have to see.

Again, it is a bomber and I shouldn't really ever need to fly at full power, but I do want to know that the power is there if I need it.

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Off to play in the shop a bit :)
 

wilmracer

I build things that fly (sometimes)
Mentor
Well.... I must have been tired when I glued those nacelle formers together last night and made a bonehead move, installing the center former upside down. I noticed this AM and I'm definitely annoyed. I MIGHT be able to remove and fix it, but TBH the right call will be to rebuild from scratch, making some adjustments along the way to work better with this build technique... So that will be this weekend's project. Like I mentioned above, the plans I'm playing with didn't account for retracts, so the "bay" where the gear goes and the wheel retracts into was going to be VERY tight. I measured and it would have worked, but I'm going to mod it a bit to get another 1/2" of space in there. I'll also tweak the design for how it mates to the main spar and how the rotation plate for the trunion will be attached.

I THINK I'll actually build out the airworthy main gear and install them in the nacelles BEFORE attaching them to the wing, and might also get the motor mounts just right as well. It will be a lot easier to work on these sections before gluing them in to the big wing.

The last purchase for parts was also made last night. Picked up some SERIOUS servos to drive the flaps. I'm using HS-5645MGs for most stuff (elevator halves, rudder, ailerons, steering, tailwheel retract) and those give a solid 168oz of torque @ 6v. That is more than enough for the "small" surfaces. The flaps are BIG though and at full deflection will see a ton of force. Got a pair of HS-7955TGs for those. Less than .09oz heavier than the 5646MGs but with Titanium gears and 333oz of torque @ 6v. I'm working on my plan to actuate the flaps but whatever I land on these servos will definitely hold up.
 

wilmracer

I build things that fly (sometimes)
Mentor
Rebuilt the inboard nacelles and started on outboard. A LOT of head scratching right now to get these right and get everything installed as far forward as possible. Inboard nacelles have more "heavy" ply to deal with landing gear forces. Outboard are mostly really light SIG plywood except for the firewall.

The remaining parts needed to mount the wing to the fuse showed up today. With the three day weekend I hope to have that done soon!
 

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wilmracer

I build things that fly (sometimes)
Mentor
Outboard nacelles almost done. Top hatches will give access for battery install. Pretty happy with this so far. Motors will get standoffs (length TBD).
 

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wilmracer

I build things that fly (sometimes)
Mentor
Dry fitting for wing attachment. Have to rethink a few things but getting closer to being able to bolt them on. Had to toss on the outboards for motivation shots.

Yeah, the shop is really messy right now :)
 

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wilmracer

I build things that fly (sometimes)
Mentor
Working out the centering/retention pins. This design is similar to the P40 but more robust due to the increased weight. I'm making some additional changes to my original plan but I think this will work great once everything is installed. I am currently thinking this large forward area will be ideal to install the sound system board, amp, and dedicated BEC. ESC extensions will likely route through the wire tubes as well, along with the extensions for the linear servos on the main gear.
 

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wilmracer

I build things that fly (sometimes)
Mentor
Making a lot of small adjustments. Got the new rear retention bolt plates built and installed too. Tomorrow may be the day I glue in the forward mount plate... closer every day.
 

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wilmracer

I build things that fly (sometimes)
Mentor
Wow man some progress that looks amazing!

Thanks! I was surprised to see this bumped up. TBH very little progress has been made in the last few months. Between work and keeping a 4 year old (and wife) entertained during COVID hobby time has ben non-existent. In preparation for likely winter lockdowns I've been doing a lot of work on the house. I've redone the TV room, a bathroom, and I'm about half done overhauling the laundry room. When I wrap that up I'll do a deep cleaning of the shop and get back to business. I do have some good stuff to share with the Nacelles and radial engine print files, and I have done some testing with the sound system and I'm thinking it is going to sound GOOD.

I am REALLY missing the hobby right now. I've only been flying about 4 times this year and really miss getting the chance to hang with and fly with everyone.
 

wilmracer

I build things that fly (sometimes)
Mentor
Radials are looking great! :)

Thanks!

Wow the detail in the completed one all painted up looks awesome. I know I have said this a few times now but I am back on my feet bill wise and caught up. I just have to sort thru some cameras and I will be able to get that video system on its way shortly.

No worries and no rush! I'm just glad to hear you're on your feet. I hope things keep looking up!
 

wilmracer

I build things that fly (sometimes)
Mentor
So I'm finally starting to get a BIT of momentum and I'm hoping sharing some progress shots from the last several months will help keep that spark alive. Work is still absolutely crazy but I really need to make time for this project for my own sanity.

When I looked at my thread on that OTHER forum I realized that I hadn't posted there in exactly 1 year, and that the last post was a response to a friend and mentor who passed away last year. For those that didn't follow John Morgan's builds he was an exceptional craftsman who loved to share everything he knew with others. He was an inspiration to @willsonman and myself and SO many others. His last comment on that thread was "Slow and steady wins the race ;)", and he was absolutely right. Even if it is slow I need to keep pressing on.

So for airframe efforts I have started installing the Nacelles. I'm being EXTRA careful with this and I'm starting with just the inboard nacelles to ensure they are perfectly square and symmetrical relative to the centerline. I've also started working on the wing saddle fillet, but I really want to get the leading and trailing edges on the wing before taking that very far.

For other activities over the last few months, I've already posted pictures of the radials. I'm pretty happy with how those and the cowl mounts came out. These should only need some minor tweaks before they are ready for use.

I re-did the rudder pedals to a much more scale version. These probably won't be seen at all with full body pilots in there, but what I had before was clearly wrong. These could be articulated by someone crazier than me (@willsonman again :p) but I won't. I'll eventually update the cockpit files on thingiverse with this version

I also did the O2 bottles. I have the generic bottle that can be scaled as needed, the 3 tank mount, and a smaller mount for a smaller O2 bottle that was in the forward cockpit. These are available at https://www.thingiverse.com/thing:4753023

The final thing I've been working on, and I'll admit this is a bit crazy, is a scale and "functional" Sperry top turret. I'm still wrapping up the beta test for that design and will have some adjustments to make, but this would be a REALLY fun detail that you might be able to see through the cockpit windows. The turret is driven by a continuous rotation servo and a belt drive with pulleys to adjust speed. Wiring passes through a slip ring and runs in aluminum tubes so there will be no binding. I still need to install the elevation servo and the FPV camera and do some coding on the horrus to make it intuitive to drive, but it should be a GREAT view (I hope).

I've got a really short clip of the turret base here:
 

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