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Old Nov 25, 2007, 02:36 AM
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Black Dog Works - 1/16th Black Planes - SR71 - B2 - TR-1A (U-2)

Been thinking about starting this thread for a while now. I thought it'd be better to have a single place for discussion on the latest Black planes in my hanger and ongoing builds.

I have a "simple" goal - build all the popular Black planes from foam, electric and to the same scale - 1/16th - so that when side by side they are the same relative sizes they would be in real life. I doubt any of us mere mortals will ever see any of these planes together in real life - if at all.

The first build was a personal fav - the SR 71 Blackbird. In real life she's 107'5" long. At 1/16 she is 6'6" and 3 lbs. Already done and flown:

vid: http://www.rcgroups.com/forums/showthread.php?t=768907

build thread: http://www.rcgroups.com/forums/showthread.php?t=749413

Next up is a B-2 Spirit - this thing is gonna be BIG. The real B2 measures 172' wingspan. At 1/16 she is 10.5'! Almost forgot, my B2 will be tail less and computer/gyro less! I decided to tackle this next as the rest of the planned black planes have been done before and appear "relatively" easier.

I've been working up to the 10 footer in stages.

First came the 3'. It used 2 CD Roms off one ESC but did not have CR props. It also uses a KF wing - Ralph I do beleive - to fly with no vertical tail.

vid: http://www.rcgroups.com/forums/showthread.php?t=768926

Next came a 7 footer. Somewhat more challenging to build but built mostly quick and dirty to explore tail less flight at this size. 2 larger CDr's with counter rotating props to minimize tourque steer.

Flys just fine with no tail. There are some structural issues with flutter, but it was build quick and dirty.

vid: http://www.rcgroups.com/forums/showthread.php?t=776889

The 10' is planned to be full house - retracts, bomb bays and bombs. It might even end up EDF - the KF wings are soo efficient.

After the B2 is done and proven, next will be either a F117 or a U2.

A 1/16 scale F117 will be about 4.3' long with a wingspan of 2.5' - perfect parkflyer size and very close to what has already been built.

A 1/16th U2 will be surprisingly small at only a 6.5' wingspan. The R version seems perfectly suited to twin pushers on the wing pods.

I welcome any and all comments or suggestions. If you want a pic of something I've done or have a suggestion to do it better I'm all ears.

I know I like surfing these sites and looking at stuff other guys do - I hope you enjoy some of this stuff.
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Last edited by Hepdog; Mar 02, 2008 at 04:57 PM.
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Old Nov 25, 2007, 07:32 AM
Now in TN!
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Chapel Hill, TN USA
Joined Apr 2001
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You have a great project going. When you do the U-2 as twins in the pods, consider the LS SPJs. They push my 4-1/2lb F-4E very well. Almost outrun the bungee on launch! And at 1.2 oz ea really help with balancing issues.
Looking forward to these.
Could you explain the KF wing in a little more detail? Not familar with it.

J
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Old Nov 25, 2007, 09:46 AM
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I may get banned or reported to the mods for posting this, but here goes....
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Old Nov 25, 2007, 11:27 AM
Now in TN!
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Very interesting. Thanks Jasta.

J
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Old Nov 25, 2007, 11:54 AM
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Quote:
Originally Posted by Jasta_66
I may get banned or reported to the mods for posting this, but here goes....
Yup, that's how I did it.

I've noticed others talk about concern over mods and being banned? Is that for real????
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Old Nov 25, 2007, 11:55 AM
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I think 3D Foamy uses the same type of wing on there prop planes. I just want to see how big of a trailer your going to need to haul these baby's around I love that SR-71, that is one sweet parkjet.
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Old Nov 25, 2007, 12:00 PM
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Ya the 7' JUST fits in the back of the mini-van - or sometimes across the car! The 10' will have removable wing panels. Still, I am thinking about buying a trailer for all this stuff. Big stuff does get hard to move around.
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Old Nov 25, 2007, 02:19 PM
That thing's operational!
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Cool Hepdog nice idea with this thread. I can't wait to see more of your cool black-works planes. I saw a real SR-71 once earlier this year, but it wasn't flying. It was located outside at an air museum in L.A., CA. It was pretty sweet though to see one up close, the SR-71's are amazing aircraft to see up close. Surprisingly, though, it seemed slightly smaller than I thought they would be in person. It was very cool though, it was one that they had retro-fitted with some extra cockpit space above the normal pilot canopy location. The U.S.S Intreprid museum has one too I think, but they moved that big carrier out of the Hudson and into some other place for repairs/retsoration.

Can't wait to see how your B-2 Spirit turns out! Man you don't mess around, that 7 footer is already giant so I can't imagine how big the ten footer will be. Looking forward also to your F-117. I want to build another one of those as well but with twin motors, are you going to go twin with your F-117.
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Old Nov 25, 2007, 02:27 PM
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Well I've only thought about the 117 and U2 a little. My experience so far with the SR and B2 sure does indicated that twins with counter rotating props are the way to go.
-More disc area for more effective thrust with higher pitched props (more speed too!)
-no torque effect at all
- cleaner installs in some cases.

The U2 is a natch for 2 motors. The 117 will be a little trickier although the V on each TE might have enough room. The 117 willl be a touch small to get real creative.

Anyway - gotta focus on the B2 - building a body on the 7' right now to see what happens if it's not totally flat.
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Old Nov 25, 2007, 03:34 PM
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"I've noticed others talk about concern over mods and being banned? Is that for real????"

No...I went off my meds on a guy in the electric vid forum who was trashing KF. The mods got involved, but its all good now, I edited the posts to remove the "offensive material".

Jasta
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Old Nov 25, 2007, 04:18 PM
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Thanks Jasta - had me concerned there was some kind of copyright infringement on mentioning KF or something (stupidz).

We all go off our meds from time to time. I like people who are passionate enough about things to voice opinions - even when they are the voice in the wilderness.
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Old Nov 25, 2007, 05:40 PM
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Quick and dirty

Quick and dirty body on the B2.

Kinda hard to tell if this was really bad - but it does affect stability. Kept it low and simple .

One test flight only - it rolled over in a gust of wind (oddly enough - wouldn't roll over before!) This time I was able to pull level just as she went it. NO major damage - the fresh snow cushioned it rather nicely - looked really cool too!

More later - Grey Cup time!
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Old Dec 16, 2007, 02:33 PM
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Been doing some research and thinking about why such a tiny little bit of body upset the apple cart so much....

First, the wing flew great with just a double KF without the body so we know that works - although I didn't know why - I think I get it now.

The KF edge at the wing tips is creating a stabalizing drag force. As one wing speeds up (yaw) that increases the drag and pulls that wing back until its in equilibrium with the other wing. In the no body vid you can see one turn where the airspeed decays and the nose nicely falls over without snapping out. I guess that was enough without the body - with the body the air catches the sides of the body more and generates more drag than the KF wing tips can handle - makes sense to me now.

The real B2 vids I've watched have the split ailerons at the wing tips almost always open to a degree. What is interesting is they seem to be open most at the lower end of the speed spectrum - take offs and landings. They close quite a bit in the at speed vids - but there aren't many of those vids around to analyse. this makes sense as drag increases at the square of speed. More speed less opening required to stabalize that tailess beast.

So if the body is going to be too much for just KF drag to handle, then I am going to go with split ailerons on the wing tips and put them on the rudder channel. If need be I can hook up a gyro although I think if I do some throttle to rudder programming I can create a proportional drag that will act exactly like the real one does in drag stabalization.

I thought about differential thrust based on SRT 10's success, but that seems a little sluggish - I prefer direct aero controls.

Sound complicated enough? This will be an all winter project - I think I may have some time today to start playing with the 12 footer.

More as any progress is made.
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