Hi Egon,

First, i'm sorry to write in English but I speak only a few words of german.

Heartiest congratulations for your splendid submarine! I’ve a question about it, in particular about the hoistable (not sure that “hoistable is the right translation of “die Ausfahrgeräte”...):
What is the component in the back of hoistable module?



I observe that it is joined to the pneumatic admission with a check valve but i don’t understand its role...

Pierre

Hi Pierre,

I think it is a little airtank for the snorkel.

Hi Matthias,

Yes I think that it is something like it. But i'm really surprised because on the two views I don' see any other pneumatic connexion on this tank than the admission with the check valve...This is why I don't understand how does it work with the snorkel.

Thats right. It is a Little pressure tank. The reason for this tank is easy, it is a emergency backup if the main tank is empty. So you can open the snorkel with the air from this small tank. But you can build it much smaller like this because you need not much air to open that small snorkelhead. The cylinder inside is appx. 2cm³ air.

regards

Sascha

Thank you Sasha for your explanation.

I think that the emergency backup don't have to be too small. If the main air tank is empty you just have the two additional piston tanks to go back on surface. But if you choose a 20% - 80% - 20% repartition on the three ballast you are just under the surface with the main ballast full and the two others empty (case of the main air tank empty). In this case you have to open the snorkelhead cylinder but also the snorkel cylinder which is bigger. Correct me if i say bullshit...

Moreover I don’t understand the pneumatic connecting of this little pressure tank: because of the check valve, the air flow can’t go back from the emergency backup to the manifolds block (PRMZ-5-M5-6 probably) even if the main air tank is empty. But is it really a check valve? (I think so because if there is no check valve, the additional air tank is not separated of the main one.)

Regards

Pierre

I`am not sure if I understand you correct. You dont need to push out the snorkelmast. The two pistontanks are enough Volume to push out the conning Tower. You have appx 1l Volume from both tanks. So you dont need more air to push out the complete snorkel. I will post you an Image of the masts from Tijgerhaai. I think you will understand better. There is no connection to the PRMZ block. You need a single valve to get an extern air backup (there are two single valve in the pic on right side). The tube comes from the main air tank across an recoil valve into the backup cylinder. The Exit will go through the single valve directly into the snorkelhead cylinder.

Red is from main air tank, green out into snorkel.

Hope that explanation was clearer. Ist very easy but a little complicate to explain. If necessary I will make a few more pics. Feel free to ask if you need something.

regards

Sascha

Hi Pierre,

I will answer the other questions which are still open. First of all, the backup pressure tank has nothing to do with emergency at all. It's just for your convenience if the main pressure tank is empty. If so, you are not able to open the snorkel head remotely, in this case you are not able to fill the pressure tank again. In conclusion you have to pull the snorkel head with your fingers until the pressure is high enough to hold the snorkel head open.
About your emergency example. As Sascha explained, both piston tanks produce enough buoyance to bring the snorkel head out of the water. More is not necessary.

There is a check valve, you can see the brass piece on Sascha’s picture, the red arrow pointed at it. The airline leads though the check valve, into the backup pressure tank, trough the (single) snorkel head valve into the snorkel cylinder.

The backup pressure tank can be quite small. Mine on the Beluga is a little smaller than the tank on Sascha’s picture. I can open the snorkel head about 50 times, although my cylinder is not the smallest.

Here you can find the schematic of the Beluga


v/r

Andy

Indeed I haven’t think about the fact that the MZH valves need a minimum of 2 bars to work. But i’ve noted it during my tests!

I have discussed about it with Aurélien Doux, a french model maker that you probably know. He convinces me to use a small air backup. I’ve baught a single valve to do it (Festo MFH-3-M5). Now I need to build the small tank. I’ve a copper tube, I can realize such a little tank than on the Beluga. I just have to machine the ends, probably in brass.

Do you have others ideas to realize it with a recovered tank?

Hi Pierre,

I used a Ø 35mm copper tube with a length of 80mm. Then I turned 2 brass caps which I hard-solder together. Today, I would build the tank smaller, 40mm length instead 80mm.

v/r

Andy