Extreme Dolfinism G2

[cdavis]

Ahh, so the Orca2, putting the length in x20 terms, is the length equivalent of an x22 or 23?

I suspected I needed to work on ankle strength.

 

[REVAN]

Ahh, so the Orca2, putting the length in x20 terms, is the length equivalent of an x22 or 23?...

It would probably be equivalent to something like a 22 or 23, as far as the length of the lever arm goes. I had built some prototypes for an X-22, but decided that the Orca2 was the better product for filling that performance segment. The Orca2 had so many advantages over the X-22 and the price separation was not large enough to justify the 22. I felt that having another product in that overlapping market segment would just weaken the foundation for both products. It would be better to have one strong product to fulfill the higher-end customer's needs, and have a recreational model, that has a larger price separation from the Orca, that is catering to those who want a monofin that is geared toward recreational diving and ease of use without any physical preconditioning or previous monofin training.

 

[cdavis]

The longer lever arm should provide better leverage, allow better streamlining and make ankle flics even more effective, all very good things for most freedivers. What d0es it do to acceleration? I was concerned when I bought my x18 that it might not have the torque and acceleration I wanted and deliberated between an x15 scuba fin and an x20. The x18 seemed a good compromise. In actual use, the x18 has incredible acceleration from a standing start, way better than stiff bifins. Will the longer lever arm of the Orca2 reduce standing start acceleration by much? A standing start assumes knees bent pretty far.

 

[REVAN]

The Orca2 acceleration is still excellent. The improved bindings make for a solid enough connection that I don't think the longer lever creates any significant handicap on acceleration.

FYI: the new DOL-Fin Pilot will be closer to your X-18 than the X20.

https://www.deeperblue.com/10-days-evil-genius-freediving-part-1/

 

[REVAN]

That may be a freediver with an X-20 there; but for some reason, I like the other one with the seashells.
I guess even I have a threshold beyond which aesthetics can become more important than how well something swims.

 

[REVAN]

I came across this from an old message I had written, and thought I should share it on the forum:

Here is something to think about...
Avro Vulcan bomber:

Boeing B-47:

These two planes have nearly the same performance (weights, speeds, lifting capacity, range), but look at how much less wing area the B-47 has to accomplish the same job. That is the difference between high aspect ratio wings vs. low aspect ratio wings. DOL-Fins are like the B-47 (long slender wing), whereas hyperfins are like the Vulcan (low aspect ratio deep delta wing). The B-47 is the great-grand-daddy of all modern airliners that still use the basic design template of the B-47. The Vulcan design has basically gone extinct. By performance, the Vulcan worked as well as the B-47, but it's design template was not as versatile or practical, and it was eventually abandoned.

 

[baiyoke]

Some very, very nice posts lately in here, including the link to the article about the history of your fins Ron.

I can now see how far you have come, and how great looking your product is now. Seeing the first ancient mono you made I can now see why your Dolfin Orca (first) ended with that design. I think your fins have an even greater potential seeing the history of your fin... In time you will let go of that first prototype, allthough in itself a very nice invention... MEanwhile the Orca 2nd gen. looks like a product allready "up there" cutting edge...

 

[REVAN]

So far, things are looking pretty good for the Orca2. The first manufactured batch of them were sold and shipped off to new owners before the new website even went online (which has been up now for a couple weeks with a new photo and video gallery if you want to check it out - www.smithaerospace.us). I'm trying to get some more of them completed before I need to leave for the DEMA Show, but there will be a hiatus in deliveries for a couple weeks while I'm away from the shop later this month.

Eric Fattah has had a least 2 ocean sessions with his new Orca2, and I've been getting some encouraging preliminary feedback from him out of those 2 sessions. I'm hopeful that between Eric and his deep cold water diving, and Chris Morey with his pool work and recreational OW diving, there will be enough information to form some kind of a comprehensive independent gear review at some point in the future.

Also, part 2 of Walter's article is out now and can be seen here: https://www.deeperblue.com/10-days-evil-genius-freediving-part-2/

 

[noa]

So far, things are looking pretty good for the Orca2. The first manufactured batch of them were sold and shipped off to new owners before the new website even went online (which has been up now for a couple weeks with a new photo and video gallery if you want to check it out - www.smithaerospace.us). I'm trying to get some more of them completed before I need to leave for the DEMA Show, but there will be a hiatus in deliveries for a couple weeks while I'm away from the shop later this month.

Eric Fattah has had a least 2 ocean sessions with his new Orca2, and I've been getting some encouraging preliminary feedback from him out of those 2 sessions. I'm hopeful that between Eric and his deep cold water diving, and Chris Morey with his pool work and recreational OW diving, there will be enough information to form some kind of a comprehensive independent gear review at some point in the future.

Also, part 2 of Walter's article is out now and can be seen here: https://www.deeperblue.com/10-days-evil-genius-freediving-part-2/

Amazing articles and even more amazing fins ! Great work Ron, very inspiring...

 

[Bill]

"By performance, the Vulcan worked as well as the B-47, but it's design template was not as versatile or practical, and it was eventually abandoned." Ron, it would be interesting to hear your comments on where the 'stealth' design fits in or on the Boeing flying wing concept plane, now that the restriction on wing span has been changed.

 

[noa]

I'm hoping the Pilot will accommodate three bolt shoes. Is the X 20 remaining or is the Pilot taking its place ?

 

[Kars]

Just an idea for Ron's Pilot foil. You offer the optional plastic bolt on "fins", which serve the two purposes of protection, and lateral stabilisation. But I figure if you want to protect your foil/pool, you can cut of a few rings inner bicycle tube and space 3, 4 or 5 out over the foil, providing a cheap local rubber aberration surface. Or maybe cover the entire foil with inner tube?

 

[REVAN]

"By performance, the Vulcan worked as well as the B-47, but it's design template was not as versatile or practical, and it was eventually abandoned." Ron, it would be interesting to hear your comments on where the 'stealth' design fits in or on the Boeing flying wing concept plane, now that the restriction on wing span has been changed.

The B-2 and Boeing's Blended-Wing-Body (BWB) are both flying wing type aircraft like the Vulcan, but neither of them is a deep-delta wing. The B-2 is a high aspect-ratio (AR) flying wing like Northrop's YB-49, and gets its pitch stability from the shape of the foil rather than the from a delta-planform. It makes several system sacrifices for the sake of stealth, but it works for its intended use. However, it is not a versatile design. If you wanted to make it carry 20% more payload 10% further, you'd basically have to design and build a new airplane. It is not a modular design like a 737 airliner that you can stretch to a bigger plane using the same basic parts.

The BWB is almost an amalgamation of the Vulcan and the B-47, in that it takes a deep delta center section and then adds the high AR wing to it. So far, it has not been demonstrated to be a practical architecture, though that could change some day.

What is interesting though, is that neither of these flying wing concepts are low AR designs. There is a relationship between span-loading and lift efficiency, and also between wetted surface area and drag. With a low AR wing like the Vulcan, if you make the wing bigger to get the span loading down for better efficiency, the wetted surface area goes up, which increases the parasitic drag and brings the efficiency back down again. These two things start fighting each other. The solution is to raise the AR of the wing to achieve a lower span loading without increasing the wetted surface area of the wing.

 

[REVAN]

...Is the X 20 remaining or is the Pilot taking its place ?

I think the real answer is that the Orca2 is replacing the X-20. I say this because the X-20 was trying to be as much of an Orca as was possible for it to be. The Pilot is more like Cdavis's X-18 prototype, what I had originally intended the X design to be. I liked the X-18 and thought it was an excellent recreational monofin, but when I realized I wasn't going to be able to make very many Orca1 fins, I tried to make the X-20 step up to supplement the shortage of Orcas. So, whereas the the X-20 was as much like an Orca as I could make it, the new products will be more federated in performance characteristics and intended use. The Orca2's performance is going up, and the Pilot is going more toward recreational use and easy monofin swimming. I'm not intending to manufacture any more X-20s beyond my current supply.

 

[divebike]

The B-2 and Boeing's Blended-Wing-Body (BWB) are both flying wing type aircraft like the Vulcan, but neither of them is a deep-delta wing. The B-2 is a high aspect-ratio (AR) flying wing like Northrop's YB-49, and gets its pitch stability from the shape of the foil rather than the from a delta-planform. It makes several system sacrifices for the sake of stealth, but it works for its intended use. However, it is not a versatile design. If you wanted to make it carry 20% more payload 10% further, you'd basically have to design and build a new airplane. It is not a modular design like a 737 airliner that you can stretch to a bigger plane using the same basic parts.

The BWB is almost an amalgamation of the Vulcan and the B-47, in that it takes a deep delta center section and then adds the high AR wing to it. So far, it has not been demonstrated to be a practical architecture, though that could change some day.

What is interesting though, is that neither of these flying wing concepts are low AR designs. There is a relationship between span-loading and lift efficiency, and also between wetted surface area and drag. With a low AR wing like the Vulcan, if you make the wing bigger to get the span loading down for better efficiency, the wetted surface area goes up, which increases the parasitic drag and brings the efficiency back down again. These two things start fighting each other. The solution is to raise the AR of the wing to achieve a lower span loading without increasing the wetted surface area of the wing.

In a practical sense how much does wetted area come into the equation , I firstly would look at shape resistance as generally being the most important factor, apart from thrust production.

 

[divebike]

Also is there a huge difference between the pilot or x20 and the orcas, this is not meant to be a slight on the orca models, as I see them as being of the highest performance monofins available for freediving, it's more of a case that by your words they seem to be substantially lesser, but looking at the designs I can't see it. I understand there is a market for the best even if it's only incrementally better. As of another interest have you ever tried to create a sprinters fin , I expect it to be larger and stiffer and or placed further back from the feet, the load on the feet is important I believe.

 

[divebike]

The load on the ankles is of interest to me, there's no way the feet can create any significant power as I see it, there importance in most fin propulsion is the change in the arc distance and or angle control, with the way that the dolfins and lunocet designs work I wonder if a little more flex built into the designs and a more direct power transfer through the line of the shin bone to what would line up approximately with the midpoint of the heel wouldn't work better, this doesn't match in well with the design of bike shoes however.

 

[baiyoke]

The load on the ankles is of interest to me, there's no way the feet can create any significant power as I see it, there importance in most fin propulsion is the change in the arc distance and or angle control, with the way that the dolfins and lunocet designs work I wonder if a little more flex built into the designs and a more direct power transfer through the line of the shin bone to what would line up approximately with the midpoint of the heel wouldn't work better, this doesn't match in well with the design of bike shoes however.

I'd say the ankle-feet-calves system can create an impressive amount of power...

 

[divebike]

I'd say the ankle-feet-calves system can create an impressive amount of power...

yea you might have me there ,that's impressive,however have you compared it to the world record for squatting,check it as a ratio

 

[divebike]

I hate being wrong let me see if I can work out a way to be right, ah I know, it's not the same as flicking with your feet, what your showing is closer to a direct lift, ah that's all I've got.