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Old Sep 17, 2012, 12:18 PM
Herk
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Virginia USA
Joined Jun 2007
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By the way - at the same time that I visited McDonnell aircraft in Saint Louis they were working on a prototype stealthy bomber to replace the Navy's A-6. From the briefings I received it sounded as if they were doing the exact opposite of what they had done with the F-15.

That plane went so far behind schedule and over cost that it was cancelled
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Old Sep 17, 2012, 12:39 PM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
3,270 Posts
Quote:
Originally Posted by HerkS View Post
By the way - at the same time that I visited McDonnell aircraft in Saint Louis they were working on a prototype stealthy bomber to replace the Navy's A-6. From the briefings I received it sounded as if they were doing the exact opposite of what they had done with the F-15.

That plane went so far behind schedule and over cost that it was cancelled
Funny you should come up with that one Herks.Some of the reading I've been doing was about the swing wing bomber-B1-B(?).I was looking for info on how it coped with the problems of variable sweep outlined earlier.That one had a pretty bumpy ride as administrations and perceived threat changed.I forget the actual figure($300m?)per unit it cost,this caused it's eventual cancellation(?)
Regards Stuart
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Old Sep 17, 2012, 03:41 PM
Deniable plausibility
Shedofdread's Avatar
Derbyshire, UK
Joined Aug 2008
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Quote:
Originally Posted by HerkS View Post
By the way - at the same time that I visited McDonnell aircraft in Saint Louis they were working on a prototype stealthy bomber to replace the Navy's A-6. From the briefings I received it sounded as if they were doing the exact opposite of what they had done with the F-15.

That plane went so far behind schedule and over cost that it was cancelled
The A12 one presumes? Now with your experience of drag rudders and tailless platforms surely that's on the build list...?

Richard
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Old Sep 17, 2012, 11:10 PM
Just call me crash for short
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United States, OH, The Plains
Joined Jan 2011
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Wow, been some goings on the last few day I've been off and about, good stuff there. Well.... After getting over my stupid attack and remembering that the servos work from PWM off the receiver, I realized that the first circuit I posted was quite incomplete, as there is a full front end missing that it needs to plug into the receiver and interpret the pulse width. So that set me to thinking of a complete hay-baby rats nest of logic gates and the like when i stumbled on these cute little 8 pin computers put out by Atmel. Don't know why I haven't seen them before now as they seem to be rather popular as they play well with the Arduino, easy to program with minimum hardware, and are dirt cheap. So, once again I sat down and cranked out, then went through more than a few tweaks in the schematic, then in the PCB router and came up with the "NEW and IMPROVED" motor direction controller posted below.

The ATTiny works with a simple program that senses the signal from the receiver. That signal, for those that don't know, (and I don't know just how it slipped my warped mind), varies from 1 - 2 ms with center being 1.5 ms. When the switch is thrown in one direction and makes the signal go at, say 1.2 ms or more, the program will tell the pin connected to one side of the H bridge to go high, and hold the other side low causing the motor to turn in direction 'A'. When the ATtiny85 sees a frequency of, say 1.8 ms or less, (switch thrown the other direction), it will send the other pin high and the first one low, causing the motor to see a reversed polarity and spin in direction 'B'. Center frequency with a .6 ms dead zone (60%) will hold both pins low and the motor will just sit there. The program could be set to drive both output pins high, acting as sort of a electronic break, but given the pitch of the screw it is not even close to being needed, and all it would do is suck down battery power while providing noting in return.

Anyway, mull it over, and please find whatever faults you can with the circuit. The way my luck runs, there just HAS to be something wrong with it.

Mark
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Last edited by Quick61; Sep 17, 2012 at 11:16 PM.
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Old Sep 18, 2012, 01:24 AM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
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Mark you're a genius!You may think you owe me one(phooey!) but the work you're doing here goes beyond and above that.
Regards Stuart
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Old Sep 18, 2012, 02:51 AM
Just call me crash for short
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United States, OH, The Plains
Joined Jan 2011
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Originally Posted by Stupot46 View Post
Mark you're a genius!You may think you owe me one(phooey!) but the work you're doing here goes beyond and above that.
Regards Stuart
Genius? There you go calling me names. Na, as they say, I'm just a thinker. Anyway, I have to say that, because THAT gives me the excuse to snag up on one of those Arduino boards to program the chip with. Sure, I could build a programmer for ~$5 or so but it won't have all the shiny features, and I have further plans for these chips on down the road, so there's that. This little project will let me really cut my teeth into this world of microcontrollers and this project get's to be my lab rat, so to speak. I'll try to get the program up in a day or two for the most of you to look over and those that might know a little (or allot) can tell me how I'm doing.

Mark
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Old Sep 18, 2012, 04:42 AM
I don't like your altitude
Stupot46's Avatar
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This came to mind:-)
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Old Sep 18, 2012, 06:24 AM
I don't like your altitude
Stupot46's Avatar
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Originally Posted by Shedofdread View Post
The A12 one presumes? Now with your experience of drag rudders and tailless platforms surely that's on the build list...?

Richard
The brothers would have recognised that one!
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Old Sep 18, 2012, 08:24 AM
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Kent, UK
Joined Nov 2004
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Originally Posted by Shedofdread View Post
One presumes that as the wing sweeps back, the [effective] airfoil becomes less thick and cambered as a % of chord length. The increased spanwise flow (with increased sweep) may further exacerbate that effect.
Norm's view is that this isn't the case....

http://www.rcgroups.com/forums/showp...0&postcount=45
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Old Sep 18, 2012, 09:08 AM
I don't like your altitude
Stupot46's Avatar
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Originally Posted by miniphase View Post
Norm's view is that this isn't the case....

http://www.rcgroups.com/forums/showp...0&postcount=45
That's the same discussion that I mentioned earlier,thanks for putting the link up.
Regards Stuart.
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Old Sep 18, 2012, 09:54 AM
Deniable plausibility
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Derbyshire, UK
Joined Aug 2008
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Right! I'm going to have to put the kettle on and ponder this one... ("Miss Goodnight - hold my calls")
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Old Sep 18, 2012, 10:46 AM
I don't like your altitude
Stupot46's Avatar
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Originally Posted by Shedofdread View Post
Right! I'm going to have to put the kettle on and ponder this one... ("Miss Goodnight - hold my calls")
While you're in pondering mode(could be a double cuppa session)
How many layers of which weight of cloth will I need for the plates.
Could I use x layers of glass,and a layer of carbon on the mating sliding surfaces.
I was thinking of hot wiring the wing root discs out of pink foam,using either dowels or carbon tubes to keep them rigid and glass and/or carbon as the plates.
Your thoughts would be appreciated.
Regards Stuart
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Old Sep 18, 2012, 11:30 AM
Deniable plausibility
Shedofdread's Avatar
Derbyshire, UK
Joined Aug 2008
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To be quite honest Stuart, to advise on matters like this, I'd need to see all this laid out in front of me. PM / call me if you want me look at this.

Richard
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Old Sep 18, 2012, 12:14 PM
I don't like your altitude
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Originally Posted by Shedofdread View Post
To be quite honest Stuart, to advise on matters like this, I'd need to see all this laid out in front of me. PM / call me if you want me look at this.

Richard
Thanks Richard,I should have a working drawing done in the next few days.
Regards Stuart
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Old Sep 18, 2012, 02:07 PM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
3,270 Posts
What I hope will be the final drive layout.The motor is at the tail end.
I've shown the nut in 15* and 45* positions;in this configuration the arms are pulling the wings outward,which is better.I've tried to keep the centre as narrow as possible,hence the cut out around the(possible)weight shift lever eye.(Too long,I'll refine that when I do a 3 view on some bigger paper)

Not shown are the aluminium guide rails,these are fixed to the upper and lower disc joiner plates.
Stuart
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