Santos Dumont No. 18 Hydroplane 1907 by Greg Davis - Scale 1:16

[Greg Davis]

46 minutes ago, druxey said:

It looks as if some modifications were carried out between the two photos.

 

- The steering column is shorter and more angled in photo 2.

- The hydrofoil mounts look to be in the same relationship to the wheel in both pics.

- Either the aft end has been shortened (unlikely) or the whole 'cockpit' moved aft about two feet.

 

Comments or criticism?

I don't think there was a prototype as much as the No 18 Hydroplane was a 'work in progress', it seems to have been the case that Santos-Dumont modified many of his creations as they were built and tested.

 

The top picture that Craig posted was taken earlier than the bottom picture. The top picture is a reflection of this photograph (Henrique Lins de Barros sent me copies of some original pictures of the boat):

At this time the engine had not been attached to the boat. The second picture was taken later when the engine was in place and the boat was essentially complete. A couple changes are noticeable between the two pictures, the covering of the pontoon has changes from one that has longitudinal stripes to being a solid color. Another, functional, change is that there is a lever in Santos-Dumont's right hand in the early picture - I have assumed this was to be a throttle; in the second picture the lever is missing and additional  controls are now connected to the steering wheel.

 

For me, it is hard to say if the steering column has been changed because the pictures are taken from different angles. The steering wheel looks to have similar height wrt his chest.  S-D's leg looks straighter in the second picture, but this could also be from moving the saddle back a bit without moving the platform.

 

Since my model is to have the engine, my work should better approximate the later photograph. 

 

It's hard for me to work this one out as I feel (without photographic evidence) the rear hydrofoil structure should mount at a hoop location as this would minimize the number of holes / bolts needed to hold the craft together and maximize its strength. If I follow this line of thought, I should attach to one of the last two hoops - the second to last may be a bit to forward, but the last one I have might be to far back. The other options would be to attach just to the stringers between the last two hoops and/or add another hoop between them for attachment purposes. I'm not really fond of those solutions because it ruins some of the symmetry in the model.

 

I really appreciate the feedback and advice that all of you are providing and I hope it will help lead me to a satisfactory solution to the rear hydrofoil and cockpit locations.

 

Thanks to all of you!

[iMustBeCrazy]

Looking at it this way I think the rear foil mounts to the same ring as the foot brace. The support for the steering column mounts to the next ring, the board extends from the end of the steering column to just aft of the seat, the foil is also wider than the earlier one. Greg, note the flag in the pic you posted, probably for signalling the tow boat.

Still guessing though.

 

[KeithAug]

Quite an exposed helmsman position. I hope his hat is tied on.

[Greg Davis]

17 hours ago, iMustBeCrazy said:

Looking at it this way I think the rear foil mounts to the same ring as the foot brace. The support for the steering column mounts to the next ring, the board extends from the end of the steering column to just aft of the seat, the foil is also wider than the earlier one.

I think you noticed the key to what happened - I've stared at these pictures countless hours and never noticed the change in the platform location! I wonder if after some trials, SD found that the rear end was not staying down enough so the platform was moved back to provide additional leverage. 

 

I'm now planning going forward to leave / position the rear hydrofoil on the second to last hoop and keep the the platform in the pushed back location.

 

Thank you so much for sharing your observation.

 

Greg

[Greg Davis]

A while back I chemically blackened the pontoon harness. 

I've looked at it for days - disliking it more and more. Today I stripped the structure back to clean brass. I'm now going to prime and then paint it aluminum. Hopefully that will get this back to a lighter color seen in photographs of the craft:

I've spent a lot of time wondering as to what metal was used in the boats construction - steel, aluminum, other. It is known that the propeller is aluminum and the color of the pontoon harness / engine pylon seem to be similar. Blackening was not good; hopefully painting is better!

[KeithAug]

The aerodynamics of the prop leaves a lot to be desired. It looks like they made it out of some left over canoe paddles. It is surprising how light weight the framework is. Are you planning to install the bracing wires Greg? I think you are right about the colour of the frame.

[Keith Black]

 Good call on the frame, Greg. What is up with that prop, it looks like some sort of KitchenAid attachment. 

[AON]

Could it have been galvanized pipe?

[KeithAug]

It is going to be very delicate once finished. I think it will need a case.

[Greg Davis]

11 hours ago, KeithAug said:

The aerodynamics of the prop leaves a lot to be desired. It looks like they made it out of some left over canoe paddles. It is surprising how light weight the framework is. Are you planning to install the bracing wires Greg? I think you are right about the colour of the frame.

Yes, I will be 'rigging' the model. 

 

It seems that SD really liked the big aluminum propeller blades. From the pictures of his machines that I've seen, the only craft that used a more modern two-bladed wooden propeller was the Demoiselle - his final airplane.

[Greg Davis]

5 hours ago, AON said:

Could it have been galvanized pipe?

That does seem reasonable, now that you mention it! Months ago, I had looked into the history of aluminum tubing and it didn't seem to fit quite right for the time period. So I did then think more about steel tubing as it was being used in the bicycle manufacturing process and it is said that SD had made use of bicycle wheels from Peugeot on the 14bis. Related, the steering wheel on the hydroplane may be Peugeot as well. Anyway, I hadn't thought about galvanized steel - the zinc coating would give the lighter color and importantly the rust proofing for his creations! 

[Greg Davis]

1 hour ago, KeithAug said:

It is going to be very delicate once finished. I think it will need a case.

Yes, that is a good idea. If all goes well, I would like to have the model finished by mid-May so that I can bring it to a model boat and ship contest that is held about a hours drive from my home. It would be unfortunate to have it damaged in transit and/or by touchy fingers!

[iMustBeCrazy]

11 hours ago, Greg Davis said:

Anyway, I hadn't thought about galvanized steel - the zinc coating would give the lighter color and importantly the rust proofing for his creations!

I've had a look and a long think and my 2^c goes to painted steel.

 

The following two pics tell the story, the suspension upright and the bent support are bare metal in the first pic, both are the same colour and not aluminium. 

In the second pic the suspension upright looks like bare steel at the top and except for that bit both are now coated in a pale colour (it could be any pale colour, pale grey, pale blue, pale yellow, pale red, pale green, any pale colour) but not white.

The other struts with the flattened ends, well aluminium doesn't like that unless it's soft and then it bends really easily. It could be done but I suspect not.

 

Steel bicycle tubing seems the most likely.

 

[Greg Davis]

9 hours ago, iMustBeCrazy said:

I've had a look and a long think and my 2^c goes to painted steel.

 

The following two pics tell the story, the suspension upright and the bent support are bare metal in the first pic, both are the same colour and not aluminium. 

In the second pic the suspension upright looks like bare steel at the top and except for that bit both are now coated in a pale colour (it could be any pale colour, pale grey, pale blue, pale yellow, pale red, pale green, any pale colour) but not white.

The other struts with the flattened ends, well aluminium doesn't like that unless it's soft and then it bends really easily. It could be done but I suspect not.

 

Steel bicycle tubing seems the most likely.

 

Craig -

 

Amazingly clear images - how do you do that????

 

There are some references to the hydroplane in terms of coloration - light blue / bluish-grey had been reported. 

 

I'm waffling on the color I'm going to use. 

 

Greg

[iMustBeCrazy]

2 hours ago, Greg Davis said:

Amazingly clear images - how do you do that????

I used Topaz Photo AI to upscale them, it's not perfect so you have to be careful about what you believe.

 

2 hours ago, Greg Davis said:

I'm waffling on the color I'm going to use. 

I don't blame you, there are so many colours that fit.

 

Given it's a light blue grey one of these might fit:

And converted to black and white (well greyscale):

 

I'm leaning towards the middle two.

 

Or perhaps a little more black and a little less blue.

 

 

Edited Sunday at 08:20 PM by iMustBeCrazy

[Greg Davis]

Thank you Craig for all the help you are providing!

 

I looked more at pictures of the boat and decided that the pontoon harness should be lighter in color than the blue/grey pontoon and nacelles. So I've gone more toward the grey tone with a touch of blue.

 

I looked though all the blue and grey offerings in the Vallejo Model Air lineup and went to the local Hobby Town and picked up a variety of possible colors. Did some tests on brass tubes to see what they looked like as well as how they matched up with the other materials used in the model. Finally decided on using Vallejo Model Air Grey Blue:

Here's what it looks like now:

I think this looks much better than when it was blackened.

[Keith Black]

 I like it, Greg, I like it a lot. Much better. 

[iMustBeCrazy]

52 minutes ago, Greg Davis said:

I think this looks much better than when it was blackened

I agree!

[mtaylor]

Given your research, I believe you're right about the time frame.  Also, I doubt they would have welded 2 dissimilar metals as that's just asking for trouble if it can even be done.

[KeithAug]

Greg - I have to agree with previous comments - much better. Black just hides the detail.

[Greg Davis]

Got a bit excited and needed to post a picture! The harness is now permanently attached to the pontoon. The wooden engine mounting strips were drilled to match the mounts on the engine block. The strips currently are spaced by blocks and are overly long - they will be reduced to the correct size when it is time to secure the engine in place. Here I have test fitted / set the engine in place and was quite satisfied to see that the harness is plenty strong and everything seems to line up as needed.

I'll be able to continue some of the work with the model set on the original building jig. I had not glued the supports so that they could be removed for special purposes. Here the second support is removed and there is actually space to mount the hydrofoil below without interference from the jig. The second support from the rear has also been removed so that there is space for the rear hydrofoil mounting structure.

 

Onward we go - it is nice to see the subassemblies fitting!

[KeithAug]

Greg. It would be interesting to understand what the angle of the centre line of the engine is relative to the centre line of the hull. Clearly with it being mounted so high the tendency would be for the moment of force to push the bow lower in the water. This of course could be counteracted by angling the front of the engine up relative to the hull. Also the torque reaction is going to force one of the sponsons down and the other one up. This could be counteracted by moving the centre of gravity of the engine to one side. I can't tell from the phots whether Santos took any of these points into account. Do you have insights?

[Keith Black]

So radical, really fun watching this come together. 

[Greg Davis]

21 minutes ago, KeithAug said:

Greg. It would be interesting to understand what the angle of the centre line of the engine is relative to the centre line of the hull. Clearly with it being mounted so high the tendency would be for the moment of force to push the bow lower in the water. This of course could be counteracted by angling the front of the engine up relative to the hull. Also the torque reaction is going to force one of the sponsons down and the other one up. This could be counteracted by moving the centre of gravity of the engine to one side. I can't tell from the phots whether Santos took any of these points into account. Do you have insights?

In correspondence with Professor Catalano, a professor of aerodynamics at the University of Sao Paulo and Santos Dumont researcher, he wrote: 'He was unsuccessful after the powered model lateral instability in water.' After reading this, I thought of the problems WWI fighter pilots had with torque from their plane's engines. From a physics perspective, mounting the engine on a pylon would only serve to make that type of problem worse. I then wondered why he didn't try to correct this using an asymmetric design. I didn't think of moving the engine, but rather moving one of the outriggers / nacelles further away from the main pontoon. I'm also guessing that the reason we have discussed the cockpit location was partially due to the instability problem - leveraging his weight further to the rear would have helped with the bow getting pushed down. I have no idea why he ultimately gave up on the project - perhaps it just wasn't as interesting as flight to him! 

[KeithAug]

7 minutes ago, Greg Davis said:

I then wondered why he didn't try to correct this using an asymmetric design.

Yes, that seemed to be sensible to me Greg. However a symmetrical design for a display model is much more aesthetically pleasing.

[Greg Davis]

11 minutes ago, KeithAug said:

Yes, that seemed to be sensible to me Greg. However a symmetrical design for a display model is much more aesthetically pleasing.

True - and we're not trying to redesign this iconic hydroplane!

[iMustBeCrazy]

1 hour ago, Greg Davis said:

The harness is now permanently attached to the pontoon.

Greg, I hate to ask but how are you going to cover the pontoon?

[Greg Davis]

7 minutes ago, iMustBeCrazy said:

Greg, I hate to ask but how are you going to cover the pontoon?

Craig -

 

No I am not covering the model - it will be done as a framed model.

 

With that said, I have considered using the turned pontoon and nacelles (that I made to 'test' my plans) to make a second model at some point. That model would be completely painted and would show no internal components. However, this is pretty low on my to do list!

 

Greg

[Greg Davis]

Just a bit more progress for today - this is the start of the attachments that will hold the hydrofoils to the pontoon harness and the rear metal work. 

 

The brass sheet was drilled to the diameter of the brass tubes and then the pieces were soldered together. The brass sheet will be bent/fitted to the hydrofoil shape on this spare piece of shaped wood. Then I can trim them up for a good fit to the actual hydrofoil pieces. The thin ones are going in the back and the wider ones in the front. I'll paint these to match the other metal structures.

[Greg Davis]

I made a small jig to bend the hydrofoil shape into the brass. I added a brass rod to the jig so that the tubes in the attachments would be in the same fore-aft location after being bent.

The four attachments are getting close to their final shapes now - just a bit more adjustment mostly to correct 'spring back' from the initial bending. Here I'm taking a look at how they fit to the hydrofoils when mounted on the boat. I've added all the subcomponents I have finished for this picture as I was curious on how the whole piece of work was coming together.