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aerohead 06-28-2008 01:29 PM

aero-mods,installment#11(aftbody streamlining/boat-tails)Part-1 Introduction
Note from Darin (admin): this installment is part of a series posted by Phil (aerohead) about the effectiveness of various aero mods - usually with quotations and citations to source data.

See the Aero mods data index here.

End note.


After a month of pouring over my notes I decided to quit looking any deeper. An associate of Bucky Fuller has commented "Sooner or later you've got to shoot the engineer,or nothing ever gets built," citing Fuller's inability to "finish" anything, and constant noodling and modification of his designs. And so as not to fall into the same trap, I've cut off my research into boat-tails and will post now instead of later.

I've waited 'til the end ( yes it's a pun ) to comment on aftbodies,as I believe it remains the least understood aspect of streamlining,deserving of the most space,time,and attention.

Since it IS a lot of material,I'll break it down into more bite-size bits,beginning with a brief historical timeline.

GENERAL NOTE: As aerodynamics is but a branch of fluid-mechanics,it will serve ecomodders to look beyond vehicles for shape and form inspiration. Presently,the Massachusetts Institute of Technology is attempting to build a robotic tuna. The United States Navy has been trying to unlock the mystery of dolphin swim-speed since 1962 without success.Present nuclear submarine design has taken a leap backwards to the fish-shaped 1900 USS Holland, The United State's first submarine,designed by an out of work schoolteacher. NASA is trying to design "tail-less" aircraft,to reduce drag,and they are also attempting "body-morphing" technology for aircraft, based on stooping Perrigrine Falcons, which plummet to Earth,wings folded,at up to 257-mph ( 414 km/h ).

The list is endless.

Rockets, jets, airplanes, sailplanes, Zeppelins, blimps, artillery projectiles, bullets, land-speed-record cars, hydroplanes,trains, trucks, buses, turbines, pumps, bridge foundations, insects, ships, boats, canoe, yachts, kayak, sail-boards, Yale racing skulls, submarines, torpedoes, whale, dolphin,shark, seal, rays, turtle, fish, squid, alligator, crocodile, tadpoles,etc..

They are all fair game in fluid mechanics!

SuperTrooper 06-28-2008 03:25 PM

Reading about the Peregrin Falcon caused me to ponder one of nature's great questions:

"What is the air-speed velocity of an unladen sparrow?"


aerohead 06-28-2008 04:24 PM

I don't have any numbers,but as I was driving to town today to begin posting,sparrows escorted me off the property.They were "bounding",where they flap for a bit,then fold up their wings completely,"bounding" like a horizontal bomb,then flap again.Their airspeed may not be great,but their body length per unit of time is impressive!

Blue07CivicEX 06-28-2008 07:33 PM

Is this an african swallow or a european swallow?`

trikkonceptz 06-28-2008 08:23 PM

Bridgekeeper:Stop. Who would cross the Bridge of Death must answer me these questions three, ere the other side he see.
Bridgekeeper: What... is the air-speed velocity of an unladen swallow?
King Arthur: What do you mean? An African or European swallow?
Bridgekeeper:Huh? I... I don't know that.
[he is thrown over]
Bridgekeeper: Auuuuuuuugh.
Sir Bedevere: How do know so much about swallows?
King Arthur: Well, you have to know these things when you're a king, you know.

Xringer 06-28-2008 11:55 PM

"According to Gray’s paradox, dolphins swim faster than they should be able to. Since Gray, scientists have discovered flaws in the details of the paradox, although some explanations of these creatures’ aquatic grace have proven to hold more water than others."

Marine technology inspired by dolphins' speed

Interesting reading. I've seen dolphins riding the bow wake on a ship,
but until now, I never knew they used drafting on other dolphins..

aerohead 06-30-2008 04:16 PM

where would we be without Monte Python?

Vwbeamer 01-12-2012 07:22 PM

not much info, i'm I missing something??

aerohead 01-13-2012 05:31 PM

not much

Originally Posted by Vwbeamer (Post 279464)
not much info, i'm I missing something??

I'm not sure either.All this is from many years ago and my notes are scattered all over.
The thread 'Aerodynamic Streamlining Template' evolved from the aero-mods series.If you'll work your way through that thread,you should get a pretty good feel for the what and the how of aft-body mods.
Apologize for dead end.:eek:

redyaris 01-13-2012 07:53 PM

Finding the activation triger point between paperwork and the real thing is always a challenge. It has been my experiance that until I actualy start building something I will never find many of the mistakes I am making. It take about three attempts at the real thing before all the bugs are worked out, so as you suggest it's time to start fishing...:thumbup:

smck 01-13-2012 10:21 PM

So even sparrows pulse and glide? Go figure.

aerohead 01-14-2012 01:54 PM


Originally Posted by smck (Post 279666)
So even sparrows pulse and glide? Go figure.

They look like a miniature peregrine falcon doing a horizontal stoop.Extremely streamlined!:)

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