Not Aero-metric. Squeeze, not Aero-metric

[J English Smith]

Thanks for the clarification, Richard. I wondered why the 616 was not a true aerometric - I knew that it was not, but did not know exactly why. As I don't fly much, the refinements of the 51 are nice to own, but not essential to me on a day to day basis. But I do wish that the squeeze fillers of the 616 worked better. More and more, I remove the "cage" and squeeze the sac to fill it. As a $2-6 pen, 616s are still an amazing value. 51s are more satisfying to use overall.

 

Interesting too that the Hero 100 does copy more of the 51 filler...

[jmkeuning]

I have a sweet aerometric Hero 237-1. Great XF nib, great aerometric filling system.

[richardandtracy]

As a direct result of this thread, last night I used a #75 drill to drill a small hole in the side of the breather tube of one of my Hero 616's. I now have an Aero-metric (by Richard's definition) H616.

 

The practical difference? None that I could discern.

 

Regards

 

Richard.

Edited October 16, 2008 by richardandtracy

[OldGriz]

As a direct result of this thread, last night I used a #75 drill to drill a small hole in the side of the breather tube of one of my Hero 616's. I now have an Aero-metric (by Richard's definition) H616.

 

The practical difference? None that I could discern.

 

Regards

 

Richard.

 

Do you really ??????? Read again what Richard said "a key element is the inside diameter of the breather tube" .... is the inside diameter of your 616 breather tube the same as a Parker 51 Aero breather tube...

The inner diameter of the breather tube combined with the small hole drilled in the tube is what made the Aero work in aircraft... it is a matter of more than just putting a hole in a breather tube as Richard points out to the poster who asked about doing it to a Skyline....

 

[jmkeuning]

I drilled a hole through the side of the hood. Now to fill the pen and take a flight!

[richardandtracy]

As a direct result of this thread, last night I used a #75 drill to drill a small hole in the side of the breather tube of one of my Hero 616's. I now have an Aero-metric (by Richard's definition) H616.

 

The practical difference? None that I could discern.

 

Regards

 

Richard.

 

Do you really ??????? Read again what Richard said "a key element is the inside diameter of the breather tube" .... is the inside diameter of your 616 breather tube the same as a Parker 51 Aero breather tube...

The inner diameter of the breather tube combined with the small hole drilled in the tube is what made the Aero work in aircraft... it is a matter of more than just putting a hole in a breather tube as Richard points out to the poster who asked about doing it to a Skyline....

Yes Griz, it is an aero.

 

The thing that makes an aero work is the ratio of the breather tube cross sectional area to the aero hole cross sectional area. I know the diameter of the inside of the P51 breather tube (0.85mm on the one I took apart recently - I had to drill out the solidified ink & not the tube with a 0.8mm drill) and I have drilled an aero hole in another P51 aero with a #72 drill (that was one size smaller than the corroded hole in the original silver tube). The ratio of areas is 1.79 Breather tube:Aero Hole. The Hero breather tube was 0.8mm diameter; I used a #75 drill, while the nearest ratio drill was a 0.6mm (don't have) or a #74 which I don't have either [broke it a while back] - the #75 was slightly closer to the P51 ratio than the nearest metric size I had (0.5mm). The error in ratio's is about 25%, with my hero's hole being a bit small relative to the breather tube. None the less, the cross sectional area relative to free volume in the sac is within the range covered by the P51 when varying between full and nearly exposing the end of the breather tube. As a result, it will have no noticable difference in its 'aero' behaviour compared to a P51 aero.

 

But as I said, at ground level, I can't determine one iota of difference in its behaviour.

 

Regards

 

Richard.

 

Edited when I felt a bit more technical.

Edited October 17, 2008 by richardandtracy

[RevAaron]

Let's all fly somewhere for a vaction.. er, business trip! Do a bit of pen testing. We all wear white hospital-gown-paper-type outfits so everyone can know what leaks when.

[simonrob]

Let's all fly somewhere for a vaction.. er, business trip! Do a bit of pen testing. We all wear white hospital-gown-paper-type outfits so everyone can know what leaks when.

 

I've flown a few times with a piston-filled Pelikan in my pocket; no tubes, no holes and... no leaks.

 

Simon

[dumdummuoi]

I am enjoying this thread immensely. And no one ever believes me when I tell 'em there's a lot to learn about fountain pens other than how to use them ^_^

[adallak]

I need a drawing of an Aero-metric system to understand this, please.

Here is the patent related to Parker 51. By the way, this is my first post. I have been lurking for a while and like the forum very much. Hope to post again.

http://www.google.com/patents?id=1PtsAAAAEBAJ&dq=2223541

 

Calbei, nice find.

Edited October 25, 2008 by adallak

[Robert Hughes]

Welcome to FPN, adallak, and thank you for the link to the P51 patent. I've looked at the diagrams and read the first page. It's quite interesting and instructive, as we FPN'ers are pretty well acquainted with the workings of the P51. It is good to get the definitive explanation from the original sources.

[solitaire]

I found that truly informative. The drawings by Dillo clarified it nicely.

 

I don't know the date of the first passenger plane with pressurised cabin but when the Parker 51 arrived few if any aircraft were presurised. The old timers told me that when going over mountains they'dfind some of the passengers nodding off due to oxygen lack!!

 

Thanks everyone

 

Solitaire

[yucki8aby]

What's the difference between Vacuumatic and squeeze fill?

[Garageboy]

Vacumatic has a plunger and a diaphragm.Instead of a sac, the barrel is the resevoir

[Richard]

Yes Griz, it is an aero.

 

The thing that makes an aero work is the ratio of the breather tube cross sectional area to the aero hole cross sectional area. I know the diameter of the inside of the P51 breather tube (0.85mm on the one I took apart recently - I had to drill out the solidified ink & not the tube with a 0.8mm drill) and I have drilled an aero hole in another P51 aero with a #72 drill (that was one size smaller than the corroded hole in the original silver tube). The ratio of areas is 1.79 Breather tube:Aero Hole.

Nope. You have the ratio wrong. The original hole size was a Nº 77 drill, not Nº 72. The diameter of a Nº 77 drill is 0.0180" (0.4572 mm). The inner diameter of the tube is 0.0370" (0.9398 mm). The correct ratio is 2.055... But this isn't all of it -- why didn't Parker use a bigger tube and a bigger hole? The size they used was chosen because fluid resistance is a function of friction, and the friction in a breather tube is a function of both diameter and length. A shortened tube of the right diameter is not as effective, nor is a full-length tube of larger diameter; neither produces the desired resistance against the flow of fountain pen ink.

[Splicer]

Sorry, I have a dumb question. What about the non-capillary Parker 61s? Are they real aerometrics or just squeeze-fillers?

[Titivillus]

... The size they used was chosen because fluid resistance is a function of friction, and the friction in a breather tube is a function of both diameter and length. A shortened tube of the right diameter is not as effective, nor is a full-length tube of larger diameter; neither produces the desired resistance against the flow of fountain pen ink.

 

Can you expand on this statement a little more. It's been a few years since I studied transport phenomena ( flow of fluids in tubes) but I seem to remember that friction isn't a function of the pipe diameter although wall drag might be. Are you talking about the relative roughness of the inside tube as well as fluid density and dynamic viscosity

 

Kurt

 

 

[Richard]

Sorry, I have a dumb question. What about the non-capillary Parker 61s? Are they real aerometrics or just squeeze-fillers?

They're squeeze fillers.

[Richard]

... The size they used was chosen because fluid resistance is a function of friction, and the friction in a breather tube is a function of both diameter and length...

 

Can you expand on this statement a little more....

Maybe friction isn't the right word, I'm not a fluid engineer by training. The overall resistance to flow, whatever it's called (drag?), is an inverse function of diameter and a direct function of length.

Edited December 23, 2008 by Richard

[Titivillus]

... The size they used was chosen because fluid resistance is a function of friction, and the friction in a breather tube is a function of both diameter and length...

 

Can you expand on this statement a little more....

Maybe friction isn't the right word, I'm not a fluid engineer by training. The overall resistance to flow, whatever it's called (drag?), is an inverse function of diameter and a direct function of length.

 

I guess as a chemical engineer being called a fluids engineer is about right.

 

The sizes of the tubes in a pen are going to have capillary action as a large part of the force. Length of the tube isn't going to be much of an issue talking in the lengths that would be in a pen but tube diameter would.

 

Kurt