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

Optical sensor

Optical sensor

Optical sensor

Hi, I am looking at designing a piece of equipment that will reduce the vibration in a small scale RC Helicopter. For this I am looking to measure the phase of the helicopter and the dc motor I will be using as the shaker. To then ensure the motor is 180 degrees out of phase with the helicopter. The question I have is how will I design a circuit to utilise an optical sensor to collect phase information of the helicopter and then the dc motor? Thank you in advance for your input

RE: Optical sensor

There are throttle matching systems for gas powered R/C airplanes so that one engine is kept at the same RPM as the other. The setup could be set so the pick-ups are 180 out of phase if you wanted that.

RE: Optical sensor

Shaggy1505... In addition to 3DDave's comments...

The following 'Duhhhh lesson learned' is an important element in aircraft vibration...

In the 1980s I worked on several propeller driven Vietnam era aircraft. We were constantly dispositioning repairs for odd/annoying cracks, chafing/galling, etc.

During the examination of one aircraft [OV-10A] for a 'slow climb-rate problem' it became evident that the variable pitch prop-blade pitch settings [for each blade] and blade-tip-tracks were out-of-tolerance. The defective prop assys were replaced and the 'newly overhauled assys' were precision evaluated/re-adjusted for matching-everything: blade pitch, variable pitch synchronization, blade-tip-track and [Duhhhh] dynamic [on-engine] balance.

We also discretely 'sanded'* the top-coat paint finish on the spinners, wings, booms and stabilizers to attain a much smoother appearance... since the paint was noticeably grainy/rough all-over [to the touch]. Although the sanded aircraft looked 'odd' [to say the lest] the results were a much 'smoother' skin surface texture.

[* using jitter-bug sander with fine-weave Scotch-Brite pads and a ‘light-touch by the mechanics’... HOWEVER, we didn’t touch the paint on balanced control surfaces]

The results of this evaluation, adjustments and maintenance actions were like a lightning-bolt hitting us engineers and the maintenance team squarely in the brain!

Critical attention to these static/dynamic elements made for [instantly] one of the 'smoothest-running-fastest-climbing aircraft' in the fleet. It was more than evident that attention to these 'small static/dynamic details' had an amazing effect on the entire aircraft: performance and vibration-wise.

We took this lesson to heart. All fleets of prop aircraft were re-examined in-light-of-these lessons-learned on this one aircraft. The maintainers and flight crews noted a vast reduction in damage/discomfort and an improvement in the quality of ‘everything else’: flight-performance improvements, reduced noise/vibration, diminished structures/systems problems, etc.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

RE: Optical sensor

Thanks for the information Wil! As usual you bring additional detail due to your vast knowledge. I do appreciate you input to this community.

RE: Optical sensor

Although an interesting post Mr Taylor I’m not sure what help this is to my original question/problem?

RE: Optical sensor

Shaggy, I think the point was that you might spend some time trying to static-balance the pieces of the helicopter to reduce the imbalance, before trying to compensate for the imbalance in flight.

I also wonder if the simple eccentric spinning around one axis, even if you can get it exactly phased, will be able to counterbalance the helicopter's motion, which may not be a simple planar sinusoid.

Maybe you could fly a recorder and a six-channel accelerometer first, to get a handle on the problem you are facing, before trying to develop an automatic system to compensate for the problem.

Mike Halloran
Pembroke Pines, FL, USA

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


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