×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Formula to determine thrust using area, torque, pitch, etc?

Formula to determine thrust using area, torque, pitch, etc?

Formula to determine thrust using area, torque, pitch, etc?

(OP)
I'm a computer geek with an idea, but I'm a bit lost as to implementation and need the formulas to work with.

I'm trying to design a variable-pitch dual blade VTOL.  I can 'do the math' if I know what the input for the problem is.  The way I see it, I have to design the blades based on the engine and adjust the pitch from zero (no thrust) to x degrees (maximum thrust) at y RPM and z torque (or efficiency), but I have no idea what the formula is for diameter, width, speed, area, torque, etc...  I expect the blades to be straight, as opposed to curved, recurved or anything like that - the math for that is way too hairy.  This is a straight thrust vector problem, applying the thrust straight down and I'm not planning on using rotation of pitch for forward propulsion as with a helicopter.  It's not something I studied in engineering dynamics.

I have a gross vehicle weight in mind, but can adjust it as needed depending on materials used, engine needed, and a few other items.  But I need to do the math before I start the design so I know what kind of specifications for the powerplant and rotors I'll need for various weights in the design.  Aerodynamic flow is actually not much of a consideration.  It ain't gonna be a fast craft (about 100-150 MPH tops)

Oh, and does anyone know the thrust to weight ratio for a straight ascending line at, say, 250 and 500 feet per minute may be?  I don't expect the crafct to go higher than, say 10,000 feet, and I can deal with air density changes once I know where they go in the formula.

Can anyone help?  Thanks in advance!

RE: Formula to determine thrust using area, torque, pitch, etc?

Its not cook-book, there are infinite variables, and even the experts get it almost right sometimes.
I would suggest Rotary Wing Aerodynamics, by Stepnewski and Keys, Dover publications, as a good basic discussion.  But designing blades is one tough job, structurally and aerodynamically.  It is a critical structure, in a whirling centrifugal field, with dynamic stability concerns, attachment structural concerns, structural modes, dynamic oscillations, and the like to make it complex.  Plan to pack a lunch, it is an all-day job.

RE: Formula to determine thrust using area, torque, pitch, etc?

nlappos hit the nail on the head. In addition to the publication he suggests....Read pubs by Ray Prouty or try to contact him via email...I think he writes for Rotor&Wing again.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close