Infinitengines "Dreamair" pneumatic speargun

[popgun pete]

Seatrophy be aware that distracting comments about too many extra guns, things being unnecessary, inefficient, wrong size, etc, plague the Russians forums where squabbles and backchat, "I thought of it first, no you didn't" comments derail threads and send them for a hundred pages and more. We don't want that here, read and then comment as the rest of us do.

 

[seatrophy]

however if a tank was dented on an oval piston “Dreamair” then it would cause a problem for the big oval sliding piston sliding past the dent by creating a tight spot, a problem which would not occur with a three chamber carbon fiber gun as the inner bore would be completely isolated from external knocks.

seems like no one yet did not see the main problem with Dreamair is a OVAL cylinder and OVAL cylinder cut ... i did not see any reason to make barell cut oval at all except to be original, but technically that foolish, bcoz under pressure tube will be deform non equal side by side if you cylinder cut other form than round
and that lead to lost the pressure

seems like inventor does not have any special technical education,
anybody see anywhere oval cylinder and piston which supposed to work under pressure ?

 

[seatrophy]

E.g. I don't think one can categorically say a carbon reservoir will loose air. And honestly it's potentially a quite damaging thing to say about the design.

did you know what exactly inside of those carbon reservoirs of you guns ? maybe inside just the same aluminum covered for wow effect by carbon?
i don know, am just ask

at least the same technology used for carbon tank for divers ) but they have reason to do so bcoz weight of divers oxygen tank a really heavy
they did not use pure carbon exactly for this reason ..carbon loose air pressure by time

 

[Diving Gecko]

There's no aluminum in my barrels - Now you know.
They are made with unidirectional carbon fiber at 0/90 degrees and one cosmetic 3K twill weave outer layer plus a sprayed on top coat. It's not exactly hard or "exotic" to make carbon tubes any longer.

Have you done a test with a carbon barrel at 10 bar to prove that it looses air? Otherwise, perhaps you could try to trust that Dreamair would not put a gun on the mark that leaks? Or that I have not seen my guns loose air?

If you have more questions about my guns then please ask them in the appropriate threads. Not this one.
Apologies to the rest of you for side tracking this thread.






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[Diving Gecko]

seems like no one yet did not see the main problem with Dreamair is a OVAL cylinder and OVAL cylinder cut ... i did not see any reason to make barell cut oval at all except to be original, but technically that foolish, bcoz under pressure tube will be deform non equal side by side if you cylinder cut other form than round
and that lead to lost the pressure

seems like inventor does not have any special technical education,
anybody see anywhere oval cylinder and piston which supposed to work under pressure ?

Your theory is somewhat correct. But please take into account the low pressures this gun will operate with.

And if you want to keep attacking this design then you have to back up your statements with real evidence. Perhaps try to run computer simulations of the deformation if you can find out the material, the thickness and construction method. Otherwise, you are just assuming the gun will fail. (I would guess that a simulation would show negligible deformation with no real world impact).

Also, just because things haven't been done before does not mean it can not work. Otherwise, we would still be living in caves. Perhaps the first man who ever decided to ride a house was laughed at...;-)

We all speculate from time to time on this forum but in general we do not make unsubstantiated - and potentially damaging - claims like yours that a gun will categorically not work.


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[seatrophy]

1 It's not exactly hard or "exotic" to make carbon tubes any longer.
2 But please take into account the low pressures this gun will operate with.
3 If you want to attack this design

1 seems like technology passed forward
2 why just 10 bar ? alloy tube can handle 30 bar ...gun can be much powerful
3 it is not about attack this design, am just trying to understand every details of Dreamair concept , bcoz a year ago i was on crossroad what to build? classical roller gun or pneumatic roller gun,
that subject still interesting for me

 

[Diving Gecko]

1 seems like technology passed forward
2 why just 10 bar ? alloy tube can handle 30 bar ...gun can be much powerful
3 it is not about attack this design, am just trying to understand every details of Dreamair concept , bcoz a year ago i was on crossroad what to build? classical roller gun or pneumatic roller gun,
that subject still interesting for me

Ah, sorry for the misunderstanding. Apologies for taking your questions the wrong way.

10 bar or less for the Dreamair as the area of the piston is much, much larger than in traditional airguns. So, with higher pressures the force on the piston would make it impossible to load the gun. The intended pressure is mentioned somewhere earlier in the thread - it may even be a little lower. Can't remember.
Of course a bigger piston means a little bit more friction and a bit more power lost to moving the heavier piston but lower overall pressure might be good for longevity of the seals and perhaps an easier construction in terms of making the barrel strong enough.

Yeah, Carbon fiber manufacturing seem to be whole lot more affordable and easy to do now. It's a more mature technology now and more widely used.

As to oval vs. a circular piston, I agree it seems like a bit of an odd choice. Pete had his worries, too. But I think Andreas can get away with it in large parts because of the low pressure and since it is nothing like an engine where the pistons move millions of times.

It would be great if Andreas would share why he went with an oval piston at first. If I had to guess perhaps he wanted a low pressure/high piston area solution but also wanted to keep the gun from being too tall which would make it harder to track a fish. So, perhaps he needed to make the piston oval to keep the gun slim?


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[popgun pete]

Many of seatrophy's questions would be answered if he read all the thread from the beginning, but he seems to be unwilling to do so. In fact now I see why threads blow out where I think he comes from as I have seen him on www.apox.ru.

If he read the patent then he would have seen the alloy gun was originally a cylindrical bore flanked by two crescent shaped side tubes and these were connected by ports at the front of the gun. The oval tank was adopted to simplify the construction of the gun, also the oval piston cannot rotate in the barrel bore. The carbon fiber gun has a cylindrical bore with side tubes just as in the original patent, it has a smaller piston and runs at a higher pressure. All this has been written earlier on this thread.

 

[seatrophy]

Many of seatrophy's questions would be answered if he read all the thread from the beginning, but he seems to be unwilling to do so. In fact now I see why threads blow out where I think he comes from as I have seen him on www.apox.ru.

sorry Pete but i didn't find out any technical data about Dreamair on first 3 pages, it is not my fault!
gun inventor not present here on topic either , to ask hem about this gun personally
we all still do not know many important information about that gun
shooting range, price, gun mass,longitude, etc
actually am just about to be 3 week noticed that some one realized a pneumatic speargun ! WOW! that gotta be cool ! and i interesting about how efficient and useful that TYPE of gun in compare with others, is why on this topic

and the same about apox.. only from this forum few day ago am noticed that some one realized a hydro roller gun WOW!, like a did in 2015
if you where so attentive big brother who is watching me on the web around.. u where noticed that am registred on apox just a few day ago and post only 2 messages by now
just after i read about hydro roller gun here in deeperblue

well... am out of this discussions, coz it getting too hot

 

[popgun pete]

sorry Pete but i didn't find out any technical data about Dreamair on first 3 pages, it is not my fault!
gun inventor not present here on topic either , to ask hem about this gun personally
we all still do not know many important information about that gun
shooting range, price, gun mass,longitude, etc
actually am just about to be 3 week noticed that some one realized a pneumatic speargun ! WOW! that gotta be cool ! and i interesting about how efficient and useful that TYPE of gun in compare with others, is why on this topic

and the same about apox.. only from this forum few day ago am noticed that some one realized a hydro roller gun WOW!, like a did in 2015
if you where so attentive big brother who is watching me on the web around.. u where noticed that am registred on apox just a few day ago and post only 2 messages by now
just after i read about hydro roller gun here in deeperblue

well... am out of this discussions, coz it getting too hot

Everything known about the “Dreamair” gun is written on this thread, except for that known only to the inventor, because I worked much of it out myself as I am an applied physicist and an engineer and also have knowledge of most of the world’s spearguns. The operating principle is simple and there are no mysteries, only thing unknown is how well the gearing in the gun loading works when cocking it, everything else is known as we have seen how the gun shoots. I wrote this up for people to read, not for my own amusement. If you could not read beyond page 3 that is up to you. Casting aspersions on the inventor’s technical knowledge when you know nothing got you off to a bad start. As for price there has been no indication, the gun will be available in different sizes and that will determine the shooting range.

 

[popgun pete]

Still looking forward to putting something in the rear of this vehicle!

 

[popgun pete]

Here it is, the Carbon Dreamair!

 

[popgun pete]

Looks to be a stable gun platform and consistent shooter even when pumped up to 24 bar. Note that the piston inside the Carbon gun is smaller and is not oval as in the alloy gun and from memory is about half the cross-sectional area. The two loaders, the simple version and the block and tackle pulleys in the hooks version, both work OK as can be seen in the video. If you look at the graphs for each shot then you can see the gun power going up and up as the pressure in the gun is increased. Not very noisy, just the usual pneumatic click.

 

[Diving Gecko]

Good to see some progress and I am getting intrigued.
Doing some simple math, the piston diameter is around 25.23mm (perhaps, it is 25mm and the piston area quoted was rounded up). That lines up well with the force graph for each pressure. And that kind of force is incredibly high for an airgun.

Let's compare the Dreamair at 21 bar (which seems to be the second highest pressure it is taken to in the video).
A Dreamair Unreal at 21 bar has 107kgf on the piston.
A Mirage at, say, 35 bar has 47kgf.
A Sten at 25 bar has 34kgf
So, it has more than twice the power of a Mirage and almost three times that of a traditional oleo pumped very high.
I think the Dreamair even has more force on the piston than Dima's hydropneumatic tuna gun, so probably more than a Black Sea, too.

Now, and here's a huge disclaimer, as it is extremely hard to judge this from the video, but just looking at the shots they don't seem hugely powerful... It looks to be using three wraps of shooting line, but I don't see a huge tug on the line at the end of the shot. And I don't feel like the shooting line "unspools" that fast either.
I would love to see a penetration test. Glue 5 pieces of that blue XPS foam together and possibly even shoot the gun against a highly optimized bandgun.

The pulley loader looks cool, I like the simplicity of using knots on the line as incremental stoppers. No need for a cleat like I put on my pulley loader. A Dreamair pulley loader with the knot-stopper design would make for a very neat little loader for regular pneumatic guns, too.

As always, the work and engineering put into this gun is incredible and it must be a world's first to have made a CF barrel for a pneumatic gun. Not only the "reservoir" but the barrel the piston slides in is CF which is def a big accomplishment.
I truly hope to be fully convinced on its power very soon

 

[popgun pete]

The highest pressure used was 24 atm, close enough to 24 bar. The 6 meter shots are pretty much plugging the target in the upper left hand corner and some go straight through the center, so that is very good. The power of the gun comes from the big piston area, somewhere on this thread I said what it was, but have not looked it up. From memory it was half that of the alloy gun in terms of the piston cross-sectional area.

I have watched the video twice, but you need to watch it in slow-mo in places to see what is going on.

 

[Diving Gecko]

The highest pressure used was 24 atm, close enough to 24 bar. The 6 meter shots are pretty much plugging the target in the upper left hand corner and some go straight through the center, so that is very good. The power of the gun comes from the big piston area, somewhere on this thread I said what it was, but have not looked it up. From memory it was half that of the alloy gun in terms of the piston cross-sectional area.

I have watched the video twice, but you need to watch it in slow-mo in places to see what is going on.

The video says the piston area is 500mm², so that's how I got the 25.23mm diameter.
And then I just used 21 bar for my comparison as it would be second highest one possibly offering more parts longevity but still, with those numbers, the Dreamair puts three times more force on the piston than regular oleos.

 

[popgun pete]

The video says the piston area is 500mm², so that's how I got the 25.23mm diameter.
And then I just used 21 bar for my comparison as it would be second highest one possibly offering more parts longevity but still, with those numbers, the Dreamair puts three times more force on the piston than regular oleos.

That area must be right because the oval piston area was 1000 square miiimeters and that is half. On the last photo taken from the video you can see it says 24 atm. The compression ratio on the earlier gun was 2.0 and is probably still the same. From the graph the peak force is 120 kg. As so much time has elapsed the details are a bit blurry now so I really need to reread my notes.

 

[Diving Gecko]

That area must be right because the oval piston area was 1000 square miiimeters and that is half. On the last photo taken from the video you can see it says 24 atm.

Yeah, but I had to pick a number for my comparison. So, I didn't max out either the Mirage nor the Dreamair. I could have done the calculations at full (24atm) power which would have the Dreamair puting 120.7kgf on the piston which is an insane amount of force for an airgun, I think even for a bandgun.

I have an apology to make. I got carried away in that previous post about the force on the differently sized pistons and forgot all about the piston pulley and drum ratio. Even though the force on the Dreamair piston is three times higher than on a regular oleo and twice that of a Mirage, I was wrong to compare piston force between these guns as the drums and piston pulley in the Dreamair changes how much power reaches the shaft. Rookie mistake, haha.

In the heat of the moment, I actually also forgot the most basic of all rules... You can't really get more power out of a gun than you load it at. And despite how advanced the Dreamair design is, it is still effectively a single stage loading gun.
The point is, you can only put about the same power into any kind of single stage loading gun and then it is up to the efficiency of the particular gun how much it spits back out. The biggest question here might be if the redistribition of how the power is stored and delivered by the drum gearing really makes a difference or not. (IIRC, in the early Dreamair material, Andreas made a point of how the drums and the redistribution would better match human physiology and allow us to store more energy during the loading phase.)

Anyhow, I can't wait to see more pics of the CF version and where he splits it, where are the openings to get inside. Also, seems like the CF version doesn't have a built-in reel. I think that's good as there are so many good reels out there already and lots of spearos are quite particular about which style they prefer and whether they want one at all or not.

 

[popgun pete]

I can tell you the price has not been decided on yet, but if you look at comparable guns the ballpark will be suggested by similar limited production stuff like Alemanni and Carbon C4, yet they don't have any inner works. All I have seen of the Carbon Dreamair is what you see, but the gun should have a handle, barrel section and muzzle as before in order to install the piston, the rear shock absorber and the axle assembly in the muzzle.

 

[Diving Gecko]

Sorry, for getting ahead of myself in those previous posts but I was taken aback when I saw the force graph on the video and the super high numbers - but now, I wonder if he is actually using the force on the piston for that graph and not the force at the wishbone which I guess would be more correct or useable?

In this graph below, the max loading force is about 120kg and that corresponds with the 120.7kgf I quoted before with a 500mm² piston at 24atm.

Also, notice the running length of the graph from app. 10cm to 70cm - what is that? The gun is a 100cm gun so perhaps in the CF version, the piston barrel runs way back in the gun and doesn't use a pulley?

P.S.
I have now asked Andres about this on youtube, so let's see if he replies