Wolfgang Haack

Haack

Minimum Drag Bullet

France had many great Mathematicians, just like Poncelet, or Didion and many more (Lagrange, Cauchy, ...).  From the successful 1940 French Campaign brought my Father some strange looking experimental Bullets. Those Bullets may be, or probably are, the Worlds first minimum drag Bullets, ever made. The Americans falsely claimed that 1947 as their Invention. The Hamburger Wolfgang Haack published (secrectly in Wartime) the corresponding Mathematics already on 9^th and 10^th October 1941 in the Heeresversuchsanstalt in Peenemünde. Now who were first? French or German? I would like to find this out. Every Fighter jet in the World today is now designed after those Rules. But who found them first? If you could help me to answer this Question, i would be very thankful.

Sincerely, Lutz Möller,

To compare a given Calibre and Length, different Design rules yields:

In other words will a competitive Shooter with a same length ideal Haack Bullet shall encounter about half Winddrift! (This "half" Guess needs some further Calculations. Just now it's just an educated Ballpark. Final Results will differ slightly).

Hi Lutz,

erst mal, wie versprochen, der Hinweis wegen des c_w-Wertes: ganz unten stehen als cw-Werte:

Haak Grenzspitze: 0.101
Haack Günstigste KL-Spitze: 0.078
Tangentialogive: 0.098

Das würde doch bedeuten, daß die Tangentialogive besser als die Haaksche Spitze sei, da 0.101 > 0.098...

Thanks und schönes Restwochenende noch!

Michael Reifenberger

Michael,

mit Wolfgang Haacks Verfahren kannst du nach allen Randbedingungen optimieren! Die Grenzspitze ist der dickste Brummer, der gerade noch günstig ist, allerdings bei größter Masse. Danach wird aber in der allgemeinen Optimierung selten gefragt. In obigem Bild werden Geschoßspitzen mit gleichem Kaliber und gleicher Länge gegeneinander verglichen. Die KL-Spitze, mit Kaliber und Länge als Randbedingung, hat einen geringeren c_w-Wert, als alle andern Spitzen.

Gruß Lutz

Lutz, Have you found any loss of BC/Cd with driving bands? Mike

Mike,

have Look at Airdrag and fiddle around with full Size and Land Size Bullets with Drive Bands.

I have great respect for McCoy's work.  However I think this program was written assuming one driving band - you have six and so six expansion and six contraction shocks to lose energy.  I am not sure this program answers this question.  Hopefully trials with an Oehler M43 will answer it accurately.

I am a bit of a sceptic and so do not believe theories unless they are tested.  And we can all be misled.  As a student of V2 (and V1) rockets you may know that V1s (I think) on average landed a bit short of London.  British censors stopped anyone publishing details or pictures of craters south of London but reported all the ones to the north which persuaded your gunners to put less fuel in them and hence they fell even shorter.  We all make mistakes including me all too often.

I have only recently come across a list of corrections to McCoy's book at http://www.eskimo.com/~jbm/bibliography/exterior.html

I attach a MS-Excel file Ogives.xls showing various low drag ogives.  One worksheet has the calculations whilst the other has the graph display.  I have included the Haack curve from your diagram and modified with ()^0.5 from which I think it is obvious which is correct.  To get a perfect tangential fit I have used a1=0.07073 rather than 0.071.

Mike

Mike,

Robert McCoy published his Work McDrag with quite a few Notes about the Accuracy and its limits. While theoretically founded in Aerodynamics the Program is more a least Square Fit to found experimental Data, than to physically describe the Bullet Aerodynamic. So read not more out of it, than has been put in.

Turbulence is rather interesting. While big Devices easily disturb the Flow, small Thing more often live in a Laminar Stream. The Reynolds Number characterises this well. In our Case with multiple Drive Bands on small Devices we introduce Micro turbulences, to avoid Macro turbulences, just as rough Shark skin, rough Air inlets on Race Engines and Turbulence generating Fences on Aeroplane wings before Land flaps. So in some Cases it pays to pay a little Price to Gain big Advantages. Such is the Case with multiple thin and shallow Drive bands. Especially when you consider your Target Rifle for 7,62x51 NATO Round, that finally is so slow to reach the transonic Region, you want a Bullet to perform well at those slow Speeds too. So your Design should not too much weigh the Supersonic Range, but emphasise the slower Regions. Bow Wave drag is to be weighed with an optimal Tail design. Now the Drive band induced Micro turbulences allow sharper Tail angles for less Bottom drag. Here you more than regain the Drag you introduced with the Drive bands.

Reasons for Drive bands

Drive bands features first Drive band tailored to fit the Throat at given Cartridge length, to guide the Bullet to complete Concentricity, a minimum Requirement to shoot for precisely. As a Benefit the Rifle shoots precisely.

Least Pressure of all Bullet Designs for given Bullet weight and –length allows higher Loads for higher Speeds. As a Benefit the Trajectory flattens, Bullets drifts less in Wind drift and flies longer supersonic.

Drive bands feature less Friction, reduces Barrel heating, and -wearing. As a Benefit, the Shooter gains better Visibility over longer Shot series in Competition; longer Barrel life, less Rifle Maintenance cost.

LM 105 Projectiles

and 8 mm F-Class

Hello Lutz How are you today?

My Name is Bill Siegloff. I am a shooter in Australia and build a rifle on a Remington 700 action sleeved. I have a chamber reamer with some subtile differences in its design with a 60 degree shoulder. I have the oportunity to have a 30" long barrel made with a 1 in 7.75" twist. I was wondering weather it would be possible to obtain some of your projectiles for testing as i am writing a technical article on the rifle buildup. I was also wondering whether you have had any troubles shooting a 300go Sierra MatchKing through your fast twist barrels as a secondary projectile. The case i use is the .300" Ultra Mag improved so it has a slight capacity advantage over a standard .338" Lapua Magnum.

I also shoot F Class and i am interested in your 8mm cartrige you developed for F Class and am wondering if you have any information you could share with me on it?

My Grandfather was born in Hamburg and my grandmother in Austria. One day i would love the opportunity to visit Germany and my father was born in Klagenfurt /  Austria after the war before they immigrated to Australia.

Thank you for your time and assistance. Sincerly Bill Siegloff, Dienstag, 20. März 2007 07:52

St. Michaelis in Hamburg from the Port

Hallo Bill,

I am a Hamburger, so You talk to the right Man!

LM-101

LM-101

Fünfmal schneller als der Schall

Hallo Lutz,

Oben A3080 und A2

der Rumpf des 5 x schallschnellen A2 hat starke Ähnlichkeit mit deinen Geschossen! Siehe Aufsatz und Bild Wer hat den hier abgekupfert?

Gruß Frank, Mittwoch, 7. Januar 2009 11:50

Moin Frank,

Wolfgang Haack hat im des Geschoßgestallt geringsten Widerstandes 1941 in Peenemünde vorgestellt.

Unser deutsche A4 in Peenemünde, auch V2 genannt

Lies seinen Bericht. Wir Nachfolger können das nur noch zur Kenntnis nehmen. Die Physik bleibt ja gleich.

Gruß Lutz