LX 64mm SR-71 Blackbird on 4S 12-Blade Power Setup

[Jpahemi1]

Today’s progress

[Aros]

Nice and clean, I dig it!

[flyjets305]

Jpahemi1 looking nice and clean, really wish you were going to takeoff from runway, dont you have access to paved runway?

@gravy you are a wild man(as Bill Murray says in Stripes "I want to party with you"-whale tale AND rudders OMG !!! Please expand on your set up, You said you have 64mm installed, whats the kv and what size esc? how does that get up in the air with a 4s 5000 wow!?!?

Im going to fly this weekend with the 4s2600 with the stock motors, (still waiting for the new 64mm motors) if it handles that i will try 4s3000

[Gravythe clown]

LOL, I'll Have to see if I can find if I posted all my build info on RCgroups. It's been a couple in not few years since I've built her. The whale tail is just for elevator and actually trimmed with a little up in her wit a single servo for control. The two pieces are connected with a steel rod. I believe but will have to check my program that my Ailerons are still elevons.
Ruder were put in just in-case i get into flat spin situation. so I have them setup with full trows and lots of expo. Normal flight needs very little rudder. In my fist one that I made a pusher prop setup no rudders, I did get into a stall with flat spin. it came down from about 100' flat as a pancake spinning. nothing would get it out. Surprisingly enough not much in damage. Not sure if rudder would have gotten it out of it but, I added it just in case.
I might pill it out and fix the hinge and take her out again soon. If I do I'll definitely get video.

Gravy

[Jpahemi1]

Flyjets
i do have a nice runway. Just don’t have the gear in yet
john

[Aros]

I could have used that tail rudder mod in one of my Blackbirds...Got into that dreaded flat spin...Watched helplessly as it just kept flat spinning from about 200 feet up all the way to the ground. When I got there I was expecting a bunch of black foam pieces to pick up. Instead she was fully intact! Not a scratch! Landed in some tall grass...Got lucky that time.

[flyjets305]

John , I revisited the idea of thrust tubes after some lite research , lol, I know Aros mentioned thrust tubes, but I dont recall if he actually installed any.
It would be interesting to see the difference in performance with and without the tubes. Are yours permanently installed? if not, I would request a before and after test flight and review.before
i go crazy and try to duplicate the excellent job you did installing yours.:-)

[Aros]

Yes out of my 13 airframes, I would say 10 of them had thrust tubes installed. I never ran a numbers test but just the eye test alone was significant. I would guess top stock speed was around 65-70mph and with nothing but just the thrust tubes added I would say bumped the top speed to 85-90mph easy. With my best setup (Don's wicked) my top speed was well over 100mph.

[Jpahemi1]

Flyjets
My thrust tubes are epoxied in. I used the 2 pdf files that Don designed and posted on RC Groups the thread is called Wicked Powered SR 71. One is the thrust tube and the other is the tailpipe support ring.
I used this as a starting point and modified the tube length and exit diameter. It’s not all that tough to make the tubes. To cut the rings, I used my jig saw and a 2” sanding drum on my drill press.
If you need help let me know
john

[Gravythe clown]

Found my post with my info on my power setup.
May27 2017
“Well after finishing up my B-2 and seeing this thread pop up again, I decided to start on my SR-71. I'm going to use the same FMS 64mm 11 blade 3150kv EDF units I put into the B-2.
So my AUW is calculated at 1450g's. So each putting out 1150g's at 40A should work just fine.

So edf' ordered and 50A esc ordered. Got the front and back glued together today minus the belly pan. Whale tail done and connected. Split rudders constructed and just need to put in servos. I plan on useing a channel for each rudder so I can set up an air brake for after I land (right rudder left yaw and left rudder right yaw).”

Aug13 2017
”Got mine in the air today, finally. Loving the new FMS 11 blade 4s units. I flew for 3+ minutes at mostly 65-70% throttle. She was plent fast at that. Did two WOT runs. She sounded nice, flew on the edge of disaster and landed with a babies touch.
Brought her in when my voltage hit 14v's. Check pack and at rest she had 15.4 @34%. So I could of pushed a 4 minute flight with my 4s 5000 60c. Battery was ambient temp after landing.”

Gravy

[flyjets305]

John sounds like you have a pretty nice workshop, It would be nice to get some help on this, but I dont have the access to some of the tools I would need.

Gravy, the FMS 11blade 3150kv motors are the same one that comes in the FMS 64mm F-15, that plane hauls butt! . those are the motors I ordered and am waiting on.. So those
motors will add significant power immediately, I'm still amazed you say you used a 4s 5000 pack to fly, but with those motors i guess it is possible, And I think Aros said he was using
a 4000 pack,, so I should be fine with 3000-3300 pack and hopefully be getting close to 3 minutes flight time. As I may have stated before, My main objective is to increase the flight time,
I would be perfectly happy with the stock set up if the flight time was reasonable, So if I can get close to 3 minutes with the FMS 11 blade motors that would be great.

[flyjets305]

here 's the better video of the SR-71, https://youtu.be/qYlxG-usA5Q

[Jpahemi1]

Flyjets
that was a nice flight.
Are you getting about 3 minutes of flight time?
Any issues of gatoring in the sun?
What’s you control throws set at?
CG at 78?
Are you using the recommended 3 degree of reflex
Are field is just about ready to open
thanks
john

[flyjets305]

with my 4s 2200 i am landing with timer going off at 1;30, so after its on the ground its about a 2 min flight, and the battery is around 3.75v . with the 4s 2600 i set the timer at 2 min and on the ground about 2;30, the battery is around 3.78v . My goal is to get a 3 minute flight, so I will go to 3000 or 3300mah that should do it.
No gatoring yet, I try not to leave it in the sun.
CG is set exactly as manual which is 78mm
control throws are set at low rate- 70/30 ailerons 80/30 elevator, high rates for both are at 100/0 . I havent put in high rate yet.
I havent checked the degree of reflex, but i do have the elevators set with some up trim, as it seemed a little nose heavy the first 2 flights, but now pretty level with the up trim at least 3*
good luck, keep us posted

[flyjets305]

those above times for the batteries are with 3/4 to full throttle, as it seems it would want to drop out of the sky at slower speeds. Although, it does float relatively nice coming in for landings with 1/4 to 1/2 throttle

[Aros]

Yep under some power is perfect. In my early days with this bird I would stupidly chop the throttle and dead stick her in for landings only to watch the nose inevitably pitch skyward on the flare which would almost always end up damaging the elevons. Keep some power on and the nose with a touch of up AoA and she lands easily.

[Jpahemi1]

Finally got the SR together. Since my eye sights not so good I decided to paint the top side like an A12 even though I know it’s not correct and not even the same airframe.

[Jpahemi1]

Still needs markings

[Aros]

Looks good! Like minds, I did the same thing with one of mine years back...

[flyjets305]

looks nice, just depends where the sun is with shadow effects. I try and keep mine relatively close, but when its in a bank and the sun is just right, it does make the orientation challenging!
John, i Know you got the kit, did it come with the stock landing gear?

My FMS 64mm 3150kv motors arrive today, so I should have it ready to go for Saturday, Will only be using the 4s 2600 and 2200, So it will be interesting to see if these motors make it more
efficient and give me another 30 seconds of flight time. If not I will be going up to 3000mah or 3300mah for more time.

Come on John, get that bird in the air!