Greg Davis

I don't understand the gearing by the propeller. I believe the engine was a 2-stroke, so the gearing between the drive shaft and the cam shaft should be 1:1. Is the camshaft driven in the rear with a gear between the magneto and the engine? The gearing in the front of the No17 setup looks closer to 3:1 and then maybe reversed to 1:3 later.

The 'I don't know' and "Pipe end should go to bottom of radiator' are exhaust pipes! Craig - thanks again for helping me understand this machine Greg

Keith - This is a new concept to me! Something more to learn about. Greg

It should be clear by now that I am not an engine mechanic! Getting around 1970's - 80's racing bicycles was the max for me. Is it possible that this is the end of one of the pipes and it is currently unattached. The lighter colored object could be the second cylinder in? But here is another hypothesis: There a pinion gear at 2. The disk behind the propeller has a gear in the back and runs a belt in front. The belt in front go to pulley 3 a double pulley that also has a belt that goes back to pulley 1 and drives the pump. What is curious to me is what appears to be a flip in the gear ratio between the prop and the crankshaft between when it was on the No17 and when it was finished on No18. The setup in the picture you have above would spin the prop much faster than after it was modified. It also seems that the original setup would be more burdensome on the engine as it probably requires a lot of torque to turn the propeller.

Continuing on the subject! Here is a picture of the Francois Durant model that had been prepared for the 2009 Santos Dumont exhibition at Museu da Casa Brasileria (the only other model of the SD No 18 that I am aware of). While there are many omissions / questionable representations on this model, it does appear that he had concluded that there was a belt driven water pump up front. Today, while looking at the photo you last attached, it actually appears that there may be two belts / pulleys - one vertical that would operate the water pump, and one off to the right (in the picture) with another (unknown) function: The number of accessories on this engine is crazy! As I mentioned in an earlier post, I will be making numerous simplifications as currently I don't have access to information that would allow for more - or even make educated guess on more. Best I can hope for is to not horribly misrepresent the hydroplane and to hope that other modelers find the subject interesting enough to do a better job in the future.

Craig - I feel you! Toward the end of February I spent a lot of time trying to better understand the fueling and coolant systems. I ended up having a lengthy and informative e-mail exchange with William Pearce (Old Machine Press and author of that nice paper on Antoinette engines). Here's how it went: On 2/19/2025 4:31 PM, Davis, Gregory wrote: William – With much thanks to you, I am making progress on the engine. Here’s what it looks like now. I’ve also made a brass fuel tank to add to the model. In the pictures of the No18 Hydroplane, there are two tubes / pipes that leave the fuel tank vertically, then bend over 180 degrees and go back down to the engine. Do you know the purpose of the tubes (pressurization?); but more importantly, do you have a feel for were they attach to the rest of the engine? I can’t decipher this information from the pictures I have of the boat. There is a picture of what is believed to be the same engine (when installed in the Santos-Dumont No 17 airplane). There are two pipes that come down in the same area, but to me, they look to connect to the coolant system and are perhaps unrelated to how the engine is set up for the hydroplane(?). If you can provide me with any guidance, I would truly appreciate it! Again, thank you very much as your help has been so instrumental to me, All the best, Greg _____ Hello Greg, Those parts look great. Amazing attention to detail. I've been staring at these photos for an hour, and I can't figure it out. They kind of do look like they connect to the cooling system, even on the hydroplane. Let's go down that road a bit... Maybe the tank is a coolant reservoir. The lines could be the coolant return lines pouring the coolant back into the reservoir. The middle two passages would then be the coolant lines taking the coolant into the cylinder Vee and to the front of the engine. The line then Ys into the two radiators. The outlet of the two radiators then Y back into a single line atop the central float. Coolant is then pumped back into a manifold at the base of each cylinder bank. The coolant flows up through the cylinders and into another manifold on each bank. The outlet of these manifolds pour the coolant back into the reservoir. Maybe it would work, but I don't really like it. However, I always thought the tank was a touch on the small size for a fuel tank feeding a V-16 engine. But then, where is the fuel? In the body? In the black tank that we discussed before? I just don't know. I wish we had some better images of the top of the engine. For what it is worth, it does look like the same engine and propeller in No. 17. I'll continue to think about this to see if there is a more logical answer. Again, fantastic work! Best regards, William _______ On 2/20/2025 1:44 PM, Davis, Gregory wrote: William – Is there any chance that the conical tank is subdivided with fuel in the back and coolant in the front? I think that there probably is still enough volume in the rear cone to fuel the engine for 2 kilometers and a turnabout. Greg _______________ Hey Greg, From the beginning, I always felt it was a fuel tank. I saw the downspouts with petcocks seemingly flowing to the carbs. Yesterday I thought about it being a split tank. The mounting band is probably covering any evidence of a seam, if there were one. The top certinally seems to have one "opening" with the coolant-looking tubes and another "opening" further aft. If the font was coolant and the rear fuel, it would make a lot of sense and also match up with some other (malformed) ideas that I have. Like, why have two downspouts for the fuel just a few inches apart? Surely a Y-pipe would have be far more simple and cheaper to create. Nether of the two downspouts are in the ideal location for a single-section tank, but they are in the ideal locations if the tank had two sections. Taking a different perspective... What purpose could the tall forward structure serve if the tank were just for fuel? I cannot think of one. Why is there another vent looking thing sightly to the rear? To me it looks like a cap with a vent. I'm not sure you really need that if it is just water in the tank, as I doubt the forward opening with its two pipes is perfectly sealed. I'm kind of leaning to the two-section tank theory. It is the best-fitting "shoe." Exclude the impossible, and what is left, however improbable, must be the truth. But it seems on the small side to me. William ___________ On 2/21/2025 4:25 PM, Davis, Gregory wrote: William – I like the idea of the 2-part tank and am willing to go with it until I come upon evidence to discount the possibility. So now I am trying to understand how the coolant circulation would work. Based on what you have told me and/or written about the Antoinette engines, I do understand that there is a coolant pump under the engine, that the coolant enters the jackets from the lower outside and leaves on the upper inside of the jackets. From the SD No17 setup, there is a connection from the top of the outlet piping to the tubes that go back up, over, and then into the coolant tank. I can also see that at the bottom of the radiators there is a saddle connection. There are 3 basic questions I have in terms of how the whole system connects. Once again, I am hoping that your expertise can provide guidance! Where does the funnel under the tank connect? I don’t see a direct path to the coolant pump under the engine. Is there a pair of pipes that leave the coolant returns that lead to the radiators – this would make sense to me – and is the coolant pumped into the radiators or is the flow passive? Is there a path for coolant to go from the lower radiator saddle connection back to the input pump? I am assuming the coolant system is closed, but maybe it is not – just carrying the amount needed for a run and the radiators are used so hot / scalding coolant doesn't spray out uncontrollably! I thought all of this would be obvious, but the answers are not coming to me presently. Also, currently, I believe the black box on the main pontoon is associated with pressurizing the pontoon and nacelles as there is flexible tubing leading to all three of these structures. Also, I don’t see any connections to the coolant system. I do remain curious on how that system works, but not as much so as how the coolant system ties together! Greg _____ Hello Greg, So glad you asked that question because I have already thought out how I think it works. Of course, I may be completely wrong, but it seems to fit. Coolant flows down from the forward downspout of the reservoir. It is then carried to the front of the engine where it Ys into the radiators. The Y inlet to the radiators just above the propeller It then flows through the radiators and Ys back into a single line atop the main float. The coolant then flows up a pipe (or maybe pipes) at the rear of the engine to the water pump. Each of the water pumps two outlets feed coolant to a pipe that runs under the engine and connects to a manifold that connects to the bottom of each cylinder in a bank. Coolant flows up through each cylinder’s water jackets and exits the top of the cylinder where it is collected by another manifold for each bank in the Vee of the engine. The single exit of this manifold delivers coolant back up into the reservoir via the tall vertical tubes. Gravity would allow the coolant to flow from the tank and through the radiators. Siphonic action may even help push the water back up to to the pump, but the pump is what is really pushing the water though the engine and up to the tank. Again, I may be completely wrong. But, this fits given what is visible in the photos and eliminates some of the questions that we are left with if it is just a fuel tank. Best regards, William

Craig - I really appreciate you taking the time to (re)check the blade to shaft ratio and I'm glad we came to a similar conclusion! I had been taking note of the prop/hull clearance both in pictures and in the previously mentioned video. It looks like there wasn't a good deal of space! I also had kept an eye on the approximate location where the blade tip intersects the diagonal brace from the engine pylon to the nacelles. The prop / hull clearance was the main reason that I though the first propeller mock-up didn't look convincing enough. Today I put together propeller mock-up No 3 (starting to use the SD numbering system, but don't want to make it to No 18 here!). This one is built to the 2:1 ratio and is scaled to match a propeller with a 2.25 meter diameter. This one looks pretty good to me currently. The blade shape still needs some refinement as it blends into the shaft - the transition seems a little abrupt right now. I think that some metal is coming out next. Also, I've made a decision to have the front of the engine as similar to how it sits in his workshop in this photo: The mechanics associated with the water pump up front is the same as in this photo: But not as it had been in the No17 nor when the engine was being installed on the No18: In the later (final?) set-up, it appears that the water pump is run off a belt drive from a larger pulley mounted to the propeller shaft. This arrangement wasn't present when the engine was being installed.

I found similar results when I made measurements on a number of photos. Tom - I think the shaft is proportionally longer on the 2-bladed propeller that is mounted to the No15 airplane, than on the 3-bladed used on No18 (and17). I agree that it looks much like 1:1 Craig - Generally, I'm getting close to a 2:1 ratio for the 3-bladed prop. Although it looked similar to a 3:2 ratio in at least one picture. I have a reference that claimed the prop diameter was 2.1 meters (~7 feet) and the first mock-up matched that figure, but it looks a bit too small to me. This is another try, with a larger diameter- closer to 2.5 meters (~8 feet) - and with a prop to shaft ratio approximately a 2:1. This one looks a bit to big to me! I've wondered about the prop diameter dimension; it was accompanied with length and width measurements of 10 meters and 6 meters, respectively. These three numbers were published in a document prepared for a Santos-Dumont exhibition - I don't have a primary reference for the propeller diameter. The same length and width were reported in an article published in Scientific American. (On the other hand, in one Scientific American article the nacelle length was reported as 1 meter which is clearly not true.) Also, the length (10m) and width (6m) are the nice round numbers one expects from Santos-Dumont. But 2.1 meters seems not to match! I can't seem to rectify the choice. I considered the possibility that the blade and shaft were each 1 meter and the .1 meter reflected a measurement associated with the spinner. But 10 cm (~4") is too big for the radius of the cone - diameter perhaps. So the decision will be between the semi-documented 13cm diameter (2.1 meter) or a larger 14cm diameter (2.25m), but certainly not 15.6cm diameter (2.5m). Going to need to sleep on this one - It would have been much easier to figure out measurements and shapes if the people taking the pictures in 1907 had squared up with the hydroplane - what were these photographers thinking?!

First propeller mock-up. This has some resemblance to the real one, but I think I'll probably need one or two more tries to really hit the shape. I think the blades need to be lengthened just a little bit ...

Finally a set of radiators have been fabricated! I'll paint the top and bottom caps aluminum before installing, but the metalwork is done including drilling holes for inlet (top fore) and outlet (rear aft) plumbing. Glad this is done-ish - onto another challenge: the propeller.

Which one is the Popular Mechanics plans?

That's a real nice look at the radiators! He first used these radiators on the No 15 airplane: I don't know what was used on the dirigible No 16 for cooling, nor on the No 17 airplane (which had the V16 and the three bladed propeller that made it to the No 18 Hydroplane). I don't think I noticed the radiators on the No 19 before, the belt drive always catches my attention! Greg

Craig - Are building one? I would love to see that! Greg

Here is what 9 fins look like as compared with 6. I think this will do! Still a bit of solder clean-up on the top two sets of joints. I have some smaller dimensioned brass square tube on order for the top and bottom caps. I had used 1/8" on the 6 fin attempt. It looks like I might be able to get 2mm square tubing which would give a nicer fit. Currently there are small brass strips soldered on the backside to hold the fins, but your glue and spacer idea would most likely yield a nice result - one that might get the fins even closer together than my slotted jig can achieve! Sorry about posting so often tonight, but this subassembly has just been getting to me and I the venting is helping!

New jig next to older jig - this is as close spacing as I am able to do as my thinnest slitting blade is 0.02". This will give me 9 fins in slightly more space than I had 6 before, but a little more width is going to be fine for the radiators.