Go Back   EcoModder Forum > EcoModding > Off-Topic Tech
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 08-08-2017, 02:18 AM   #1 (permalink)
Human Environmentalist
 
redpoint5's Avatar
 
Join Date: Aug 2010
Location: Oregon
Posts: 9,103

Acura TSX - '06 Acura TSX
90 day: 28.24 mpg (US)

Lafawnda - '01 Honda CBR600 F4i
90 day: 47.32 mpg (US)

Big Yeller - '98 Dodge Ram 2500 base
90 day: 21.82 mpg (US)

Prius Plug-in - '12 Toyota Prius Plug-in
90 day: 57.64 mpg (US)

Mazda CX-5 - '17 Mazda CX-5 Touring
90 day: 26.83 mpg (US)
Thanks: 3,173
Thanked 3,487 Times in 2,600 Posts
rocket aerodynamics

Why aren't rockets more teardrop shaped, especially the flared out engine cones? Why are the cones necessary in the first place? I thought all that needed to exist was a high pressure in a combustion chamber, and an opening at the bottom where the pressure was relieved.

Does aerodynamics not matter at supersonic speeds since air does not have enough time to respond?

__________________
Gas and Electric Vehicle Cost of Ownership Calculator







Give me absolute safety, or give me death!
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 08-08-2017, 06:35 AM   #2 (permalink)
Master EcoModder
 
sendler's Avatar
 
Join Date: May 2011
Location: Syracuse, NY USA
Posts: 2,935

Honda CBR250R FI Single - '11 Honda CBR250R
90 day: 105.14 mpg (US)

2001 Honda Insight stick - '01 Honda Insight manual
90 day: 60.68 mpg (US)

2009 Honda Fit auto - '09 Honda Fit Auto
90 day: 38.51 mpg (US)

PCX153 - '13 Honda PCX150
90 day: 104.48 mpg (US)

2015 Yamaha R3 - '15 Yamaha R3
90 day: 80.94 mpg (US)

Ninja650 - '19 Kawasaki Ninja 650
90 day: 72.57 mpg (US)
Thanks: 326
Thanked 1,313 Times in 966 Posts
Minimal frontal area for the work that is expected? And the large shock bubble at the front prevents reattachment of the air flow?
.
.

.
.
  Reply With Quote
Old 08-08-2017, 08:21 AM   #3 (permalink)
MPGuino Supporter
 
t vago's Avatar
 
Join Date: Oct 2010
Location: Cedar Rapids, IA
Posts: 1,766

The Karen-Mobile - '05 Dodge Magnum SXT
Team Dodge
90 day: 26.72 mpg (US)

Fiat Dakota - '00 Dodge Dakota SLT RWD Quad Cab
90 day: 16.67 mpg (US)

The Red Sled - '01 Dodge Durango SLT 4WD
90 day: 16.96 mpg (US)
Thanks: 799
Thanked 682 Times in 437 Posts
The Trident I missile has a deployable aerospike that pops out after it is launched. It causes the supersonic shock wave to form at it's tip, rather than at the nose of the missile.

Attached Thumbnails
Click image for larger version

Name:	Trident-C-4.jpg
Views:	155
Size:	13.9 KB
ID:	22368  
__________________
The Fiat Dakota


The Karen-mobile


The Red Sled
  Reply With Quote
Old 08-09-2017, 02:03 PM   #4 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 19,633
Thanks: 5,504
Thanked 6,465 Times in 5,197 Posts
Quote:
Why aren't rockets more teardrop shaped, especially the flared out engine cones? Why are the cones necessary in the first place?
The exhaust fills the wake?

Rockets perform over a wide range of conditions. The shape of the rocket bell is highly constrained. https://en.wikipedia.org/wiki/Rocket_engine_nozzle

Think bullet vs dirigible.
  Reply With Quote
The Following User Says Thank You to freebeard For This Useful Post:
Fat Charlie (08-09-2017)
Old 09-06-2017, 04:21 PM   #5 (permalink)
EcoModding flying lizard
 
Daschicken's Avatar
 
Join Date: May 2012
Location: Georgia
Posts: 725

Cibbie - '88 Honda CBR 250R
Motorcycle
90 day: 48.79 mpg (US)

Rarity - '06 Honda Accord EX V6
Team Honda
90 day: 36.79 mpg (US)

Baby viff - '86 Honda VFR 400R
Motorcycle
90 day: 42.15 mpg (US)

Latios - '08 Suzuki SV650SF
Motorcycle
90 day: 71.38 mpg (US)

Mazda 3 - '14 Mazda 3 i Sport
90 day: 45.65 mpg (US)
Thanks: 581
Thanked 257 Times in 172 Posts
Here, have a picture(or two):

Click image for larger version

Name:	SS2S.Nose.Cone.Drag.Coefficient.jpg
Views:	47
Size:	54.6 KB
ID:	22614
Click image for larger version

Name:	4.gif
Views:	76
Size:	3.2 KB
ID:	22615
__________________
-Kaze o tatakaimasen-

Best trip in V6: 52.0
Best tank in V6: 46.0
Best tank in Mazda: 47.0
Best tank in CBR: 61.3
Best tank in SV: 83.9

Quote:
Originally Posted by MetroMPG View Post
You can lead a fashion-conscious horse to unusual-looking water...

  Reply With Quote
Old 09-06-2017, 09:58 PM   #6 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 19,633
Thanks: 5,504
Thanked 6,465 Times in 5,197 Posts
Very interesting. How are secant ogive, tangent ogive, and power series defined?
  Reply With Quote
Old 09-07-2017, 12:06 AM   #7 (permalink)
Master EcoModder
 
Join Date: Jun 2008
Location: Earth
Posts: 5,209
Thanks: 225
Thanked 808 Times in 592 Posts
The (approximately) cone-shaped engine nozzles are necessary for the exahust to expand properly and produce as much thrust as possible. And as already mentioned, the expanding gas more than fills the space behind the rocket, so a teardrop tail is pointless.

As far as aerodynamics for the rest of the rocket, it just doesn't spend that much time in the thicker parts of the atmosphere. For instance, a Saturn V was at 25 km just 90 seconds after launch: https://upload.wikimedia.org/wikiped...ectory.pdf.jpg

  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com