Autorotation Question For My Invention: CopterBox
Autorotation Question For My Invention: CopterBox
(OP)
Background:
I'm the Director of Engineering of DropMaster, Inc. My patented invention, CopterBox, can be seen at:
www.dropmaster.com
Also please see the 'Why CopterBox' link on the home page:
http://m ywebpages. comcast.ne t/dropmast er/why_cop terbox.htm
There is a video, some articles and a white paper.
This information is provided for background purposes only and not for selling, as we only sell to government agencies due to liability concerns.
The Army (Natick Labs) has come to us asking for a 500 lb payload version, which I'm calling MonsterBox (the current CopterBox is designed for 60 lbs but will actually handle 100 lbs) and I have some ideas about how to increase lift. CopterBox has patented, faceted, cardboard rotor blades. MonsterBox will likely have extruded foam rotor blades with a more efficient airfoil. My main question is this:
CopterBox has always had 3 rotor blades. We can now add more, but have never really flown with 4 or 6 blades. I'm wanting MonsterBox to have 6 blades and I'm looking at innovative ways to increase lift. My primary interest is the effectiveness of (3) blades having -6 degree pitch like Copterbox (to initiate rotation) but the other alternating (3) blades having 0 degrees of pitch, which will at first not have any forward thrust but hopefully will drive the blades forward once maximum RPM has been achieved and the velocity triangles have had a chance to catch up. The (3) blades with 0 degrees of pitch will provide more lift (and drag) than the -6 degree pitch blades. There can be some vertical separation of alternating blades in case there is some adverse cascading effect. Is this approach a valid one to consider for significantly increasing lift? Another approach is to reverse rotor pitch prior to ground contact, but I'm trying to keep this simple and low-cost.
Does anyone have any input or know of someone who can help?
Thanks!
Chase
www.dropmaster.com
I'm the Director of Engineering of DropMaster, Inc. My patented invention, CopterBox, can be seen at:
www.dropmaster.com
Also please see the 'Why CopterBox' link on the home page:
http://m
There is a video, some articles and a white paper.
This information is provided for background purposes only and not for selling, as we only sell to government agencies due to liability concerns.
The Army (Natick Labs) has come to us asking for a 500 lb payload version, which I'm calling MonsterBox (the current CopterBox is designed for 60 lbs but will actually handle 100 lbs) and I have some ideas about how to increase lift. CopterBox has patented, faceted, cardboard rotor blades. MonsterBox will likely have extruded foam rotor blades with a more efficient airfoil. My main question is this:
CopterBox has always had 3 rotor blades. We can now add more, but have never really flown with 4 or 6 blades. I'm wanting MonsterBox to have 6 blades and I'm looking at innovative ways to increase lift. My primary interest is the effectiveness of (3) blades having -6 degree pitch like Copterbox (to initiate rotation) but the other alternating (3) blades having 0 degrees of pitch, which will at first not have any forward thrust but hopefully will drive the blades forward once maximum RPM has been achieved and the velocity triangles have had a chance to catch up. The (3) blades with 0 degrees of pitch will provide more lift (and drag) than the -6 degree pitch blades. There can be some vertical separation of alternating blades in case there is some adverse cascading effect. Is this approach a valid one to consider for significantly increasing lift? Another approach is to reverse rotor pitch prior to ground contact, but I'm trying to keep this simple and low-cost.
Does anyone have any input or know of someone who can help?
Thanks!
Chase
www.dropmaster.com
RE: Autorotation Question For My Invention: CopterBox
Having said that I have zero experience with auto gyros, or auto rotation in general.
Neat product, I'm astonsihed that it is cheaper than a parachute, well done.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Autorotation Question For My Invention: CopterBox
<ignoring the complexity of said linkage for now... >
If the weight also had a significant cross section in a horizontal plane, e.g. saucer- shaped, it could have enough aero drag in free fall to _partially_ stroke the same mechanism. So increased vertical velocity would cause the weight to increase pitch, and hence, lift, and slow the descent rate.
... Both problems solved. I'll bill you later.
Mike Halloran
Pembroke Pines, FL, USA
RE: Autorotation Question For My Invention: CopterBox
It's possible that the effective rotor pitch would be -3 degrees, but it will take (funded) testing to prove it. I have 1/10th scale paper models that I need to fold up and test. I think if 3 blades were at -6 degrees and 3 were at -3 degrees, there would definitely be a fight. I'm hoping for minimal negative effect until max RPM is achieved.
CopterBox is cheaper than parachutes not because of its price, but because of its lack of logistical cost. It's all on the website.
Thanks! Any other input?
Chase
www.dropmaster.com
RE: Autorotation Question For My Invention: CopterBox
Why not control the blade pitch through blade angular velocity through some simple, centripetal force mechanism?
RE: Autorotation Question For My Invention: CopterBox
Thanks!
Chase
www.dropmaster.com
RE: Autorotation Question For My Invention: CopterBox
If that is true, then perhaps you can add a pitch angle adjustment feautre/setting to your wire frame rotor hub such that by looking at a matrix you can set an optimum pitch per unit. I can imagine a couple ways to set up an feature so that during assembly you can adjust pitch at zero, two, four, and six degrees.
I spent 10 years building helicopters, my intuition says it could work. Unfortunately I am not a designer and it would not be the first time a designer told me I was full of it for thinking too simplistically.
Composites and Airplanes - what was I thinking?
There are gremlins in the autoclave!
RE: Autorotation Question For My Invention: CopterBox
Mike Halloran
Pembroke Pines, FL, USA