Project Un-flyable/Tacit Blue (90mm edf)

the rc project

Well-known member
*CHECK MOST RECENT POST FOR UPDATES*

"The Northrop Tacit Blue was a technology demonstrator aircraft created to demonstrate that a low-observable stealth surveillance aircraft with a low-probability-of-intercept radar (LPIR) and other sensors could operate close to the forward line of battle with a high degree of survivability."

thanks wikipedia.... when i first saw this plane i thought the shape (from the bottom at least) looked like a high alpha machine, although thats totally not what this plane was designed for. This was the predecessor to the b-2 and the testbed for stealth in curved shapes, engineers on the project said it was at the time the most unstable aircraft ever designed and flown. i think it would be super cool to build one fairly scale, i have a 90 mm 6s edf for this project so i want to go pretty big. At least big enough for some good retracts. i wont just be jumping into this though i've built a small scale version with a 50mm edf, just under 750grams and it took 6-7 good throws while changing the cg, this is why i built it and now that i've narrowed in on the unusually far back cg location i'm thinking maybe one more small scale with an enlarged wing and maybe fixed gear(essentially a practice plane rather than the quick and crude test model). the large scale model will be made using pink foam and fiberglass. i'm hoping to make this a more long term project so i'm looking at a maiden in December before the snow!

oh yeah and most people think its pretty ugly and was known as the blue whale by those who worked on it. let me know your thoughts. i think it looks pretty cool. cool enough to build a 90mm model? maybe this leads me to start an x plane series where i look at building some of the most unusual planes ever designed. this is my first build thread so let me know if i'm doing something wrong or to change something! Hope you enjoy the project!(yes i know the pink model looks nothing like the real one, i built it to test the wing shape and characteristics, the pics are all post crash so don't mind the battle damage)
 

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the rc project

Well-known member
Started cutting, its big, 1.25 meters long with a fuse like a bathtub! Still I will be making another smaller scale with the 50mm fan just to dial in this odd shape. The 90mm should make 3.2kg of thrust, it should be plenty to get this box flying
 

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the rc project

Well-known member
so a little more work done... landing gear will be the first thing to do, then mount the fan! its going to have a very narrow base so i expect ground handling to be a challenge but as long as it goes straight it should be okay. i'm planning on using full flying stabs but i'm unsure of the best way to do it... any ideas? that silver piece is just foam with aluminum tape to hold the shape, that will be used for the intake duct on the top of the plane. the esc is also mounted with a fan and in the intake airflow, my confidence is low for that esc but lets try to keep the temps even lower than that. i will be using an external bec for power, it will also have a small air duct and fan as well, because i think its cool...(another reason to 3d print some cool air intakes!)
 

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Flyingshark

Master member
so a little more work done... landing gear will be the first thing to do, then mount the fan! its going to have a very narrow base so i expect ground handling to be a challenge but as long as it goes straight it should be okay. i'm planning on using full flying stabs but i'm unsure of the best way to do it... any ideas? that silver piece is just foam with aluminum tape to hold the shape, that will be used for the intake duct on the top of the plane. the esc is also mounted with a fan and in the intake airflow, my confidence is low for that esc but lets try to keep the temps even lower than that. i will be using an external bec for power, it will also have a small air duct and fan as well, because i think its cool...(another reason to 3d print some cool air intakes!)
Peter Sripol did all-moving stabs on his quinjet. At 1:37 to 1:43 he shows how he did that.

 

the rc project

Well-known member
I think I’ll need more strength than that! I’m expecting 80 kph(or atleast I will build to 80kph)
I’m not sure that would hold under the stress
 

dap35

Elite member
"The Northrop Tacit Blue was a technology demonstrator aircraft created to demonstrate that a low-observable stealth surveillance aircraft with a low-probability-of-intercept radar (LPIR) and other sensors could operate close to the forward line of battle with a high degree of survivability."

thanks wikipedia.... when i first saw this plane i thought the shape (from the bottom at least) looked like a high alpha machine, although thats totally not what this plane was designed for. This was the predecessor to the b-2 and the testbed for stealth in curved shapes, engineers on the project said it was at the time the most unstable aircraft ever designed and flown. i think it would be super cool to build one fairly scale, i have a 90 mm 6s edf for this project so i want to go pretty big. At least big enough for some good retracts. i wont just be jumping into this though i've built a small scale version with a 50mm edf, just under 750grams and it took 6-7 good throws while changing the cg, this is why i built it and now that i've narrowed in on the unusually far back cg location i'm thinking maybe one more small scale with an enlarged wing and maybe fixed gear(essentially a practice plane rather than the quick and crude test model). the large scale model will be made using pink foam and fiberglass. i'm hoping to make this a more long term project so i'm looking at a maiden in December before the snow!

oh yeah and most people think its pretty ugly and was known as the blue whale by those who worked on it. let me know your thoughts. i think it looks pretty cool. cool enough to build a 90mm model? maybe this leads me to start an x plane series where i look at building some of the most unusual planes ever designed. this is my first build thread so let me know if i'm doing something wrong or to change something! Hope you enjoy the project!(yes i know the pink model looks nothing like the real one, i built it to test the wing shape and characteristics, the pics are all post crash so don't mind the battle damage)
I've seen this at Wright Patterson AFB Museum - Very cool.. Two of my other favorites are here... https://www.nationalmuseum.af.mil/V...s/Display/Article/196041/boeing-bird-of-prey/
 

the rc project

Well-known member
I've seen this at Wright Patterson AFB Museum - Very cool.. Two of my other favorites are here... https://www.nationalmuseum.af.mil/V...s/Display/Article/196041/boeing-bird-of-prey/
The bird of prey looks like it could be quite a challenge😎. Anything interesting things about tacit blue that you may know and I don’t?😂 on a more Serious note, it is hard to find (good) information on this plane so anything helps!!! Build suggestions always welcome as well!
 

dap35

Elite member
The only things I know, where on the placard under the display :). I seem to recall that it didn't have many flight hours on it.

I did see where someone posted a video on Youtube where they built an EDF B-O-P that looked pretty good.
 

LitterBug

Troll Spammer
The bird of prey looks like it could be quite a challenge😎. Anything interesting things about tacit blue that you may know and I don’t?😂 on a more Serious note, it is hard to find (good) information on this plane so anything helps!!! Build suggestions always welcome as well!
I could head over to the museum and get some pictures of Tacit Blue. On the other hand, you could also look it up on the museum web site.

https://www.nationalmuseum.af.mil/V...s/Display/Article/195769/northrop-tacit-blue/

LB
 

the rc project

Well-known member
A little more work done today! Sides of the fuse and the gear done! Almost.... the gear needs more reinforcement but until I know where everything is going it should go it should do. The width of the wheels is a little thin but I want the gear to tuck into the fuse to make it smooth on the outside(maybe even doors who knows) the fan isn’t mounted but I’m still figuring out the duct and tube for the fan.that curve at the back of the plane was so hard to do and I’m not super happy but some sanding and filler will make me the craftsman I’m not. Do you think the bend will effect the flight? As Mike patey would say... BACK TO WORK!
 

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the rc project

Well-known member
Well I just realized that I won’t be able to use a vtail programming with my nose gear steering as elevator inputs would steer the nose gear. I don’t want it to be a bank and yank so I’m THINKING about turning the very tail(kinda looks like a skirt) and make it a surface, I would have plenty of upward authority in the edf thrust path, this way I could move the vtails slightly more vertical to give me a better stability. And keep nose steering. Well this just got a little more complicated, time for another small scale...
 

LitterBug

Troll Spammer
It is an amazing place.... I have yet to make it to the hanger with presidential AC. I would also like to tour the in-process stuff too.
I am fortunate to be about 40 minutes east of it. Get over about 1 time a year.

LB
 

the rc project

Well-known member
little by little, the more I get done on this project the more I feel like I could do it better, I think if I try to keep this model light(no fiberglass) I can get it to fly well, then maybe I look at a super scale version with gear doors full flying surfaces suspension, the whole 9. There are just to many things I would do differently now, so I’ll build another!!!!

I got the fan mounted and went for the first taxi tests. Went well at low speeds but I’ll save the high speed stuff for when it’s got wings(in the pics they are just on the spar not attached). I won’t be doing full flying stabs on this version just to keep it simple because the back of my mind keeps saying, “UnStAbLe”. I’ve decide the hatch will pretty much be the whole roof as it is also part of the intake and the battery sits right under the intake(right on the Cg). Bec cooling duct is done and the cooling fans mounted, lots of wires considering the only servo is the steering servo😂. Main gear is in for good, I have to make the nose before I am set with the nose gear. Then on to the surfaces servos and sanding!!!
 

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b-29er

Well-known member
nice looking bird!! regarding the stability, a gyro prob wouldn't be the worst thing. Apparently the Tacit Blue flew worse than the Have Blue, the stealth test article for the f-117. Good luck with the test flights!
 

the rc project

Well-known member
nice looking bird!! regarding the stability, a gyro prob wouldn't be the worst thing. Apparently the Tacit Blue flew worse than the Have Blue, the stealth test article for the f-117. Good luck with the test flights!
I will likely get one for the maiden, you think it’ll be a big deal that yaw won’t be controllable by the gyro, it’s A very large plane to be bank and yank.
 

the rc project

Well-known member
Cut and hinged the flaperons, the whole reason I’m attempting this project is that this plane looks to have a very large lifting body and no direct drag from intakes. (Basically I looked at it and said “how could it not float”)With my small scale model I was able to find some favourable flight characteristics, when the cg was just right it could high alpha all day and was very pitch maneuverable. I hoping I can replicate this on the 90mm and hopefully extra size and higher power to weight makes these characteristics stick around! That being said it also expresses just about every bad tendency probably stemming from pitch and yaw instability, However this is the fine line I’m choosing to walk for this project.
 

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dap35

Elite member
I will likely get one for the maiden, you think it’ll be a big deal that yaw won’t be controllable by the gyro, it’s A very large plane to be bank and yank.
What if you put the nose gear on it's own servo since it is only used for tax? Then the gyro could run the elevons and v-tail. What kind of receiver are you using?