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Old Dec 26, 2009, 12:30 AM
Burner!!
PlaneCrazee's Avatar
United States, AR, Little Rock
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The subfins arre on the YF12, not the SR71
http://upload.wikimedia.org/wikipedi...-71A_3view.svg
http://en.wikipedia.org/wiki/File:Lo...-12A_3view.png
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Old Dec 26, 2009, 12:18 PM
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Houston, TX
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Originally Posted by PlaneCrazee View Post
You are right! My bad... my plastic model is of a YF-12A actually. I only thought that the sub-fins were commen to both the SR-71 and the YF-12A. Cwap!

For some really interesting reading about the SR-71 take a look at the wikipedia.org page on it: http://en.wikipedia.org/wiki/Sr-71

Fascinating details about how the engine cones worked to propel the plane at Mach 3 and above! How the heck engineers figured this stuff out back in the 1950's when this plane was being designed I'll never understand. These planes were so far ahead of their time it is ridiculous that they're sitting in museum's now.

Thanks for the correction on those sub-fins. The YF-12A also had a large center fin between the sub-fins that was hinged so it could be folded up against the underbelly for landings. It must've been a sight to see in the air... there are very few pics of the YF-12A though unfortunately. I think there were only 3 built, and 1 of them was later rebuilt as an SR-71 to replace a crashed plane. NASA operated the remaining 2 as high-speed/alititude research vehicles for awhile during the active service of the SR-71's.

They're all extremely cool aircraft though. It seems to me that our nation today has the best aircraft in the world, sitting in museums unused. It's very sad... the SR-71 Blackbird, the F-14 Tomcat, and soon the remaining 3 Space Shuttles. There is no replacement for what these vehicles were able to do, nothing even comes close.

- Michael
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Old Dec 26, 2009, 12:18 PM
Tweaker
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Corona Del Mar
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Redlite, very nice build! I'm curious how you will mix the whale tail, I see that are you using it as a conventional elevator, ever consider dropping it and raise the elevons as a "crow feather" airbrake??
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Last edited by RemE; Dec 26, 2009 at 12:26 PM.
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Old Dec 26, 2009, 12:38 PM
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Houston, TX
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Ok I went ahead and ordered the SR-71 from Bananna Hobby. $219 (another $28 for s&h) without the radio and without their battery pack.

What is the largest battery size that will fit in the battery compartment? Anybody know of any good sales on suitable battery packs for this bird going on right now? I see a few nice 3000 mah 35C LiPo's on sale on Ebay at the moment and was thinking of ordering a pair of them but I'd like to be sure they can fit in the plane ok 1st! Thanks!

My club's field is closely mowed grass (though we keep discussing the possibility of putting a textile runway down)... I presume I can just hand launch this thing and then land it on it's wheels with no problems?

- Michael
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Old Dec 26, 2009, 02:36 PM
Build'm,Fly'm,Crash'm
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Sacramento CA
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Hey RemE


Tanks' man.....No, but that is an option, now that you mention it....my radio has separate mix options on a couple of switches, so no big deal...I'll look into that, as a 'crow feather' airbrake sounds cool, fits the plane...

My plane will be a hanger-queen for a little bit, but first flight due up shortly....

Joe
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Old Dec 26, 2009, 05:30 PM
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Exit 4, South Jersey, USA
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Mike 211,

This plane is easy to hand launch. As for batt.s, one guy stuffed a 4.5 AH 4S in there. Pics at post 168. Good luck with it, it's a gas to fly.
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Old Dec 26, 2009, 06:05 PM
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Originally Posted by dLdV View Post
Mike 211,

This plane is easy to hand launch. As for batt.s, one guy stuffed a 4.5 AH 4S in there. Pics at post 168. Good luck with it, it's a gas to fly.
I'm more concerned about the physical diminsions... how big is the battery compartment?

I look forward to getting it in in a week or two and getting hands-on it.

Thanks!

- Michael
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Old Dec 30, 2009, 09:05 PM
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Yeah Michael I had to double check to make sure I had it right. The YF-12a was a great bird and it wouldn't take much to bash this into one.

The petromat is great, our club field has had one for the last 5 or so years.
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Old Jan 03, 2010, 12:27 PM
On the Edge of Space
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Originally Posted by PlaneCrazee View Post
Just got one in from Banana Hobbies. I's an ARF so I need ot add motors. I have 2 GWS 3900s that I'm gonna try first since I have them idle. I also have 2 30 amp TP ESCs that will work up to 3S. I'm going to use retracts. Does that sound flyable? From what I've read it may fly at least if a 3600KV flew.

Eventually I'd like to get another wicked 4000 and a couple of 50 - 60 ESCs capable of 4S.
Hey Tex, yeah, I was the idiot that flew on 3600 kV outrunners. I was so new to EDF I didn't know you pretty much have to at least double the watts/lb compared to prop planes. It did fly and was controllable, but it had a ceiling of about 60 or 70 feet that it would not climb above, and I'm only 50' above sea level! So yeah, it did fly at only around 140W/lb but it was slow. There is a plus side though. The plane was so light with that gear that crash damage was minimal, so maybe it's not such a bad thing to kind of ease into the power/weight ratio. If you read through all the threads on this plane you'll see a record of a pretty high crash rate. When its flyin good its a breeze to fly but it has some weird tendencies that sort of sneak up on ya.
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Old Jan 03, 2010, 04:09 PM
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Yeah I read it. If 3600s were what I had I'd of tried it too. It seems you got pretty good at fixing it up too.
After a full charge of 3s2p 3600 30c flightmax pack it made about 600 watts so it should be okay. on 4s 4900s it was over 900 but the escs wouldn't take that for long so 3s it is for maiden. After maiden it'll get gear doors, scale rudders touch up and scale trim for NASA ver 844.
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Old Jan 03, 2010, 04:32 PM
On the Edge of Space
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Exit 4, South Jersey, USA
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That set up should work just fine. Mine flew well on a little less then 600W, and while it wasn't what most would call real fast it was still a big hit. I mean it actually got applause at our club fun fly, and that never happens. Good luck and blue skies.
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Old Jan 04, 2010, 07:59 AM
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Originally Posted by dLdV View Post
If you read through all the threads on this plane you'll see a record of a pretty high crash rate. When its flyin good its a breeze to fly but it has some weird tendencies that sort of sneak up on ya.
I'd like to hear more about these "weird tendencies that sort of sneak up on ya"... what should a new SR-71 pilot be aware of?

I've been putting together all the notes I've read on here, what throws to use and the various CG's that people have recommended for best flight performance. Also I've watched as many YouTube videos as I can find of people flying this plane, paying attention to HOW they're flying it! I'm not a newbie, I've flown nitro 40 sized planes for many years now as well as nitro heli's... this is my first DF jet model however (don't worry, I also ordered a SkyRay DF delta-wing model which I intend to get some practise stick-time on 1st before maidening the SR-71!).

My SR-71 is scheduled for delivery Tuesday, Jan 4th. Can't wait to see if it looks as good as it does in the BanannaHobby pictures! The bats I ordered for it will be another 2 weeks or so though, so no fear of rushing to maiden it.

Thanks!

- Michael
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Old Jan 04, 2010, 08:10 AM
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Originally Posted by Michael211_2000 View Post
what should a new SR-71 pilot be aware of?


- Michael
Two things. The first is a flat spin. If you stall the airframe and it tip stalls, the process of attempting to keep the nose up usually results in a flat spin that is difficult to recover unless you have some altitude. Just don't stall it and it's fine. The next is wing rock. The long fuse and short wingspan make these a bit "rocky" in the wind..... the wings rock a bit in the wind. No effect on a dead calm day, so just be aware of the tendency.
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Old Jan 04, 2010, 09:56 AM
Tweaker
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Corona Del Mar
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You know, Gyros are so cheap you might consider adding one on the ailerons, $17.95 is cheap insurance and would stop the wing rock.

http://www.hobbycity.com/hobbycity/s...idProduct=6755
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Old Jan 05, 2010, 06:41 AM
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Jacksonville Florida
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I'd like to hear more about these "weird tendencies that sort of sneak up on ya"... what should a new SR-71 pilot be aware of?
Also, I don't have one of these planes yet, but I think I remember reading earlier on this thread that when landing the nose likes to pitch up (or the tail sinks) as it slows down. So keep up a bit of throttle when you flare for landing and then throttle off after the main wheels are touching the ground. (Actually this is a good idea with most EDF planes)

You can clearly see this happen in this larger turbine powered version. http://www.wimp.com/rcjet/
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