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Old Apr 17, 2012, 07:08 PM
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Hmmm...I didn't hear the vid too well...more details, please, on the build itself...
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Old Apr 17, 2012, 10:08 PM
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It's just a simulated SR-71
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Old Apr 17, 2012, 10:23 PM
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Kit, RTF? I must have missed something...
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Old Apr 17, 2012, 10:26 PM
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The Blackbird in that video is not a real-life RC jet. It's one of the planes you can fly on Real Flight's latest version flight simulator. I'm merely discussing how nice it would be if a real one could fly as nice as this sim version that I posted a video of.
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Old Apr 17, 2012, 10:28 PM
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Ok, I'm caught up now! LOL!
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Old Apr 17, 2012, 10:32 PM
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Whew! I was beginning to wonder if I worded it wrong! LOL!
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Old Apr 19, 2012, 11:30 PM
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I just had to chime in, I have flown almost 50 flights on airframe #1 and have done a couple of high speed passes and have cut power completely for a few seconds just to hear how draggy the airframe is. I did not feel any twist or tip-stall. I think Redlite nailed it with these very overweighted airframes that have to be flown without any mistakes! Mine is touchy and it is very light! You need to plan your flights ahead of time and have a spotter to help on approach ect.
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Old Apr 19, 2012, 11:58 PM
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50 flights on airframe #1??

Dude, I feel like you should get some kind of trophy, holy crap! I've flown this bird in just about every configuration imaginable...With gear, without gear, stock setup, custom setup...The one constant has been that I can't seem to keep her in one piece for more than a few flights at a time.

If it's not my dumb thumbs or wrong setups, it's orientation. If it's not orientation it's a bad hand toss. If it's not a bad hand toss it's a bad landing where the nose pitches up and smashes the elevons to bits. If it's not a bad landing it's a tip stall. If it's not a tip stall it's a flat spin...My word if I hadn't flown composite warbirds, various EDF jets of various shapes and sizes, scale planes, micros, all successfully for thousands of flights I would seriously think I just need to take up a new hobby.

But if you and others can do it, that gives me hope that I can too. As for my flat spin after dead stick last week, it was because I too have cut power plenty of time before with the older air frames without any issues. I swear I'm just cursed when it comes to this particular model.

What is your exact setup so I can consider matching it for weight? I agree keeping it as light as possible is a HUGE key to success.
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Old Apr 21, 2012, 12:52 AM
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I need a scale for my planes. The one thing I overlooked through this entire process was how heavy it was with that fat brick of a battery I was using. It would have been interesting to know what my AUW was versus the AUW of those of you that are having success.
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Old Apr 21, 2012, 11:42 AM
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Quote:
Originally Posted by dLdV View Post
I just ordered a Dimension Engineering Cell Shield LVC. Hopefully this will guarantee simultaneous LVC shutoff on both fans. The idea is to set the ESC LVC's at 2.5V and set the Cell Shield higher, like maybe 3.2. I'm getting a programming card from Don to set the LVC for the Pentium ESC's. The Cell Shield has a rotary switch. I plan to use a single large battery instead of two in parallel.

I have a suspicion that bad batteries with a sudden drop of knee may have caused problems on my earlier version, with one motor shutting off and the other galloping. Can't be sure of that, but this seems like cheap insurance.

http://www.dimensionengineering.com/cellshield.htm
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Originally Posted by Aros View Post
50 flights on airframe #1??

As for my flat spin after dead stick last week, it was because I too have cut power plenty of time before with the older air frames without any issues. I swear I'm just cursed when it comes to this particular model.

What is your exact setup so I can consider matching it for weight? I agree keeping it as light as possible is a HUGE key to success.
I too am thinking that you hit LVC and one side cut and the other surged. That's why I'm putting the Cell Shield in there, as I suspect it might have happened to me a number of times. As a supporting anecdote, I had a P-38 that kept crashing, doing the fall straight out of the sky routine. After the third crash I finally found out that the pack was subject to a sudden drop off. Better batts fixed it. I'm putting a cell shield in that one too.
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Old Apr 21, 2012, 08:45 PM
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Sounds like a good idea! This bird especially could use some serious redundancy.

These unstarts are a killer!
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Old Jun 04, 2012, 03:04 PM
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I've hung out in the background in this thread and decided to show a wing modification that I believe will tame this beast to a large extent.

After I tried flight one on my SR-71 and read this whole thread I came to the conclusion that this plane needed washout on the wing outer panel leading edge. I'm lucky to live close to Hill AFB and had noticed the crazy leading edge on the real SR-71. Also, several years back I designed a small B-58 and did a simple leading edge droop to simulate the real B-58 and this resulted in a sweet, stable flyer with no bad stall or any other bad habits. After my first dismal maiden flight I made repairs, including outer wing panel droop additions. Wing mod. is real easy and does not look so bad, esp when you look at the real plane and notice the crazy washout that looks like somebody dropped a bowling ball on the leading edge of each wing (see picture).

So, second flight with mod went super with CG moved back and most up trim removed SR lifted itself off with perfect elevator trim. Rolls were real axial and other then my old eyes trying hard to see plane flew nice until way out on landing setup it went into a fast turning dive, recovered and then straight in. Sad to say one motor burnt out and I could not hear. Damage was pretty bad with almost one foot of nose gone. So, rewound motor, built another nose and went out again with same results. Great take off, nice flight, then again burnt motor! This time I was close and heard it happen and shut throttle down right as death spiral started. Plane recovered and I found it to glide nice and was able to lower gear and do a good dead stick landing. No nasty pitch up, no flat spin, no need for whale tail, no need for huge up trim as far as I can tell now.

Here is a video of take off and a couple of post flight pictures that also show wing modification and new nose.

http://www.rcgroups.com/forums/showthread.php?t=1665445
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Old Jun 04, 2012, 05:22 PM
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Hey that's a great mod! Sorry to hear about the crash! That little tempermental black missile for pete's sake.

So how did you create that washout exactly? Thanks for sharing.
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Old Jun 05, 2012, 08:19 AM
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Few more pictures of simple mod. Just a sharp hobby knife and a straight edge, then sand angle and glue back with epoxy. Ends up making wing a little stronger also. I'll tray and get better flight video when I fix, or replace bad motor.

--D
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Old Jun 05, 2012, 11:27 AM
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Nice work...I may have to pull the trigger on #9...Get the PNP from BH with the retracts installed and gut it out and put Don's Wicked setup back in. No whale tail this time...Just the Wicked power and Afterburnerz and NO MORE HAND TOSSES.
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