If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #2529
Joined: Thu Dec 10 2009, 02:43AM
Location:
Posts: 600
Ash Small wrote ...
"Cyclic pitch changes are accomplished by tilting the swashplate. Collective pitch changes are accomplished by vertical movement of the swashplate. Combined collective and cyclic pitch changes result from combined control inputs by the pilot."
The Chinook steers by tilting the swashplate, thus giving more lift on one side than on the other.
The rorors , I think, from watching them (they fly over, and sometimes past the windows, of my house all the time), and due to the fact that both rotors can be driven by each engine, always spin at the same speed, relative to each other, thus cancelling out any torque reaction. Tilting fore and aft is accomplished by vertical movement of the swashplates. Foreward motion is achieved by increasing the angle of the rear rotors, thereby tilting the whole craft foreward, as far as I can tell.
Everything you've written is true, but there's the second order effects...
It's like when you fly a plane, to turn right, you move the stick to the right and it banks the aircraft. But when you fly a glider, you have to stick to the right, and coordinate it with a bit of rudder because you get differential drag from the ailerons that yaws the aircraft (this is actually why aircraft have tail rudders, the Wright brothers first aircraft didn't, and kept crashing from the yaw!!!) A lot of aircraft (but not so much gliders) have a cross coupling built into the controls, so that the rudder is thrown in for free and the pilot doesn't have to worry about it.
Also with an aircraft, if you apply only rudder, a fixed wing aircraft naturally banks, although some control systems will apply ailerons to cancel it out.
The Chinook is kinda like that, and even more complicated.
It's one of these things that pilots aren't particularly aware of.
When you build aircraft from scratch you more or less have to know the details of the particular cross couplings and make sure you can deal with them. Here, notably there is drag from the rotors, which depend on speed, and there's the various gyroscopic effects as the rotors change angles and if they change speeds.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
in high mach, roll-pitch inertia coupling is a problem that took quite awhile to understand, and several killed test pilots... And very nearly killed Chuck Yeager.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
1:57, another test flight completed. moving the battery (248g) 3 inches back allows the body to stay nearly level, instead of -20', but at 5 inches it too far back. So, having moved the battery to the 3 " postition levels the flight and reduces the significance of the nose problem, though it still exists. Im wondering if this nose up problem is entirely aerodynamic, that front is wide and long, so air acting on it would generate force. (If so, it would approximate a ball resting on the top of a concave down parababola, unstable, and accelerating.)
3:04 pm, another test flight completed. significant improvement, explained below.
This screen cap shows all my flight prgrammables features. Only some are activated.
From the larger screen cap, this shows what all previous flights were flown with, only modding these PID values.
Seen here the Level PID values, i have no explanation what these did, so in two hours i just played with the values.
I have found, that the Level PID values, (a feature which only exisists in MW2.1) results in:
First, default values are: [7, 0.010, 100] (P,I,D) Second, P=0, no movement of servos at all, reguardless of I and D. third, D=0, no movement of servos at all, reguardless of P and I. foruth, I can be zero or higher, servos still function. fitfh, with [10, 0, 100] the nose up condidtion is greatly reduced!
3:52pm, Next test flight has been completed. Lesson learned: dont let prop tip strike cement. All brass flung off. second, brass is still needed on the tips, but much less than 600mg, im thinking 200mg or less now, which will improve battery time, and roll response.
i still dont know how to effrectivly attach brass to a glass-nylon prop tip... CA breaks off after a while.
Registered Member #2529
Joined: Thu Dec 10 2009, 02:43AM
Location:
Posts: 600
OK, here's the easiest way I can explain what I think is happening. First, let's forget gravity.
There was once a guy called Gerard O'Neill.
He designed these space habitats called Island 3, great long spinning cylinders, arranged side-by-side in parallel, in pairs, which were counter-rotating, connected at the end via bearings with straight couplings in between.
Anyway, they had to keep the ends pointed at the sun.
So they had a scheme by which they could twist the pair of cylinders along an axis through the centre that was parallel to the couplings at the ends. (They had another scheme for twisting the whole structure parallel to the long axis, but nevermind that right now).
What they worked out was that if they shortened one of the couplings, then the cylinders would start to spin around the central axis, and it would only stop when they made it the same again, and if they lengthened it, it would twist the other way. As long as they weren't the same length, it would continue to twist one way or another.
I think that's what's causing your nose-up/backwards and forwards tendency.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
BigBad wrote ...
Are your rotors spinning the wrong way? What happens when you swap them over?
No, i made doubly sure i have them right...
Big breakthrough!!! first, i payed attention not just to my machine this time, but also my self, it started moving to fast., so i pitched back, with the adition of significan I value for the Pitch PID loop, the nose went up, but it wasnt catatrophic--started to level off (which had never been seen before) and then i instincively throttle back, and saw the tail drop, nose trying to stay level...
so i believe now, im contributing to the problem, by retarding the throttle in anticipation of the crash
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
If you think you might be part of the problem, try to use only half as much control effort as you think you ought to. Eg, if you want to pull the stick all the way back, just pull it halfway.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
Need Help Related to Rotational Inertia
