Official Freewing Twin 70mm SR-71 Blackbird with Gyro EDF Jet Thread

[GliderGuy]

Some of you will be shaking your head in disbelief about the stupidity!!!! Good news = all OK, no crash

Or…It might just be my specific electronics or a behavior that is unique to the SR-71 stock gyro. Who knows?

WARNING!!! I’ve always heard best practice is (1) turn on the xmitter (2) then turn on the RX.

A few times in the past with other planes, I got this backwards and had no issues. Read on…

WARNING!!! Again!!!!!

This morning was calm, so I few the SR-71 4 flights. I noted the xmitter batteries were a bit low after #2 flight. Changed the batteries and ended up getting the RX on “BEFORE” turning the xmitter on.

Everything checked out once I turned the xmitter on, so I took off.

Oh my gosh….The gyro or RX had lost its mind!!!!! It was in a hard left turn condition which took nearly full right aileron to counter.
My heart rate equaled that of Neil Armstrong’s as he landed on the moon!
I barely got it around once and landed. WHEW!!!

I unplugged the RX and then plugged it back in. Took off…all was normal. Made one more flight, too. All good.

LESSON LEARNED!!!!

-GG

PS Total flights now 48
Finding the best landings are with 3 clicks of power until wheels touch.

[GliderGuy]

You can see some of the small cracked areas in the gravel surface toward the top center of the photo above the B-2.

Correction…14 landings on NEW and beefed-up anti-torsion arms. Not repaired as stated in my prior post.

The strengthening process is:
-Remove the arm BEFORE it breaks
-Remove paint carefully with a Dremel tool
-Wash with isopropyl alcohol
-Fill all cavities with JB weld epoxy
-Thin coat non-hinge areas with JB weld
-Wrap with 0.6 mm steel aircraft safety wire
-Coat all steel wire wrapped area with JB weld
-Reinstall arm to landing gear
-Dremel away any small areas of epoxy which cause any restriction to compressive spring movement.

-GG

[GliderGuy]

Sure…Here is the best photo I have of the gravel size that broke the SR-71’s anti-torsion arms within the first 8 landings. B-2 hasn’t had issues with it other than a broken nose steering arm on one cool 45F day. The area has some very small weathering cracks which probably caused the breakage. Such a cracked area can be seen near the top center of the photo.

-GG

[EDF-Jetpilot]

Calmed down finally!!! Got 10 late afternoon flights. Total is now 44 flights. Sure is FUN!

I’ve been cruising mostly but some rolls and loops and vertical climbs after a high speed pass into a half loop, half roll over the top. Pretty tame stuff, but I’m taking my time.

Approach is slightly nose high with 3-4 clicks of power to about 3 ft…then close the throttle all the way once in ground effect. Easy to hold off and put her on the mains.

My repair/beef-up of the anti-torsion arms has now lasted 14 take-offs and landings on the gravel that originally broke them. There’s more room at this gravel surface place. So, I thought I’d experiment with the beef-up and see how it worked. So far, so good. But my goal is to move to a “smaller” place with smooth asphalt.

-GG

Great, I'd love to see it for you!
Could you post a photo of this "gravel area"? I'd be interested to see how rough it really is. It probably won't be that thick gravel. But it's always better to have no stones at all.
Sorry for my English, tis is not top!

[GliderGuy]

Calmed down finally!!! Got 10 late afternoon flights. Total is now 44 flights. Sure is FUN!

I’ve been cruising mostly but some rolls and loops and vertical climbs after a high speed pass into a half loop, half roll over the top. Pretty tame stuff, but I’m taking my time.

Approach is slightly nose high with 3-4 clicks of power to about 3 ft…then close the throttle all the way once in ground effect. Easy to hold off and put her on the mains.

My repair/beef-up of the anti-torsion arms has now lasted 14 take-offs and landings on the gravel that originally broke them. There’s more room at this gravel surface place. So, I thought I’d experiment with the beef-up and see how it worked. So far, so good. But my goal is to move to a “smaller” place with smooth asphalt.

-GG

[Aros]

Nice!

[NKC-135Fleet]

Definitely had too add the 71 to my reconnaissance fleet…. Not sure what I’ll add next but something else will join the fleet.

[Aros]

Full throttle or no throttle!!

[DCORSAIR]

I was excited to see this bird until, I heard 3 min of flight time. What are you getting for time and what battery, and how do you fly it? Thanks.

Well it depends on what battery you use and what throttle setting you like to fly it at, I can only get 2:30 flying time out of mine, about 3:00 minutes total counting taxiing out and taxiing back, I throttle back to just over 1/2-3/4 after takeoff and do some cruising around with a couple of full throttle high speed passes. I'm using the red/silver HRB 5000mah 100C batts in mine which are almost brand new and they are a little warm when I return and the cells are around 3.77, 3.80.

I love the jet and it flies really well right out of the box and is a joy to fly but it eats batteries which I do believe in my opinion is the worst I've seen from any of my EDF jets. I just can't fly this SR-71 slow so maybe I could do better but that's boring, full throttle passes are the only way to fly an SR-71..............

[GliderGuy]

I was excited to see this bird until, I heard 3 min of flight time. What are you getting for time and what battery, and how do you fly it? Thanks.

Admiral 6S 6000 and getting 3:30 and landing with reserve enough for a go-around and ending with a bit over 3.8V post-flight voltage. Most of my flying is done with a click or two more than 50% throttle stick position and a little 100% hot rodding.

With a total 50% throttle position after take-off, getting a 4 min flight should be possible. It all depends on how much reserve, how low you want to drive the post-flight cell voltage down, your battery condition and capacity, etc.

Pretty much in line with most of my EDF jets.

-GG

PS I try to end with 3.8V so I have a shorter charge time at the field. I get more flights this way.

[Aros]

I haven't maidened mine yet. Sounds like between 3-4 minutes is the average depending on flying style and battery. Actually right in line with most EDFs.

[MeyerVW]

I was excited to see this bird until, I heard 3 min of flight time. What are you getting for time and what battery, and how do you fly it? Thanks.

[Aros]

Yep, it can be done but it's definitely a high wire act.

[EDF-Jetpilot]

Oh my, yes, the Blackbird is notorious for a vertical nose high attitude if slowed/flared too much on approach. I flew the LX version hundreds of times and I can't count how many times it happened to me on approach. Luckily it rarely caused damage but looks hilarious on video. I just had it happen to my E-flite version a couple weeks back. We got a good laugh at the field. Wobble, wobble, wobble and then nose to the sky, slam the elevator stick full down and she plops down, lol.

With the Blackbird she needs to come in with speed and the nose AoA just barely over horizon. She wants to be flown to the ground, and not like an F-16 in High Alpha either.

He can land the SR-71 with high alpha... but I doubt it always works that well.

https://www.youtube.com/watch?v=t5gIJomxkAE

[Aros]

Oh my, yes, the Blackbird is notorious for a vertical nose high attitude if slowed/flared too much on approach. I flew the LX version hundreds of times and I can't count how many times it happened to me on approach. Luckily it rarely caused damage but looks hilarious on video. I just had it happen to my E-flite version a couple weeks back. We got a good laugh at the field. Wobble, wobble, wobble and then nose to the sky, slam the elevator stick full down and she plops down, lol.

With the Blackbird she needs to come in with speed and the nose AoA just barely over horizon. She wants to be flown to the ground, and not like an F-16 in High Alpha either.

[GliderGuy]

One YouTube video comment is, “Don’t stall it! The nose won’t come down…it over rotates, and it won’t recover.”

Basically a high alpha lock situation.

Has anyone witnessed this happening (crash)? Or….is this the pilot’s “assumption”?

As in full scale birds during FAA certification flights, they use spin chutes to get the nose down when experimenting with aft CG stall conditions to get out of the high alpha lock.

Worth a try if you get into an unrecoverable high alpha lock situation…pop the chute out. It might just save your bird.

-GG

[Glideman]

Anybody have the factory gyro settings for SR71 Blackbird Freewing gyro ?

[EDF-Jetpilot]

Thanks! But I’m not going down without a fight! This has been an interesting journey. Appreciate all the guidance and comments. Now we know more than we did a few weeks ago.

All three are beefed up…starting with a good wash/scrub with isopropyl alcohol:

1) Voids are filled with JB Weld epoxy
2) The entire length of each 1/2 is wrapped in 0.6 mm steel aircraft grade safety wire embedded into a layer of JB Weld before the epoxy cured
3) An outer covering layer of JB Weld is painted over the entirety of each 1/2.

I’m also going to fly ONLY on smooth concrete or smooth asphalt…,no gravel. No more 40F flights…warmer air temperature flights to enhance the metal’s flexibility.

I hope all this will make them last. Spares will be kept on hand once they can be ordered because 100s of flights is gonna stress my attempts to beef them up. Dremel removal of the black paint down to bare aluminum before 1, 2, 3 above will be a first step, if they are painted black.

-GG

OK... good! You seem to be a real model building genius.

[GliderGuy]

Thanks! But I’m not going down without a fight! This has been an interesting journey. Appreciate all the guidance and comments. Now we know more than we did a few weeks ago.

All three are beefed up…starting with a good wash/scrub with isopropyl alcohol:

1) Voids are filled with JB Weld epoxy
2) The entire length of each 1/2 is wrapped in 0.6 mm steel aircraft grade safety wire embedded into a layer of JB Weld before the epoxy cured
3) An outer covering layer of JB Weld is painted over the entirety of each 1/2.

I’m also going to fly ONLY on smooth concrete or smooth asphalt…,no gravel. No more 40F flights…warmer air temperature flights to enhance the metal’s flexibility.

I hope all this will make them last. Spares will be kept on hand once they can be ordered because 100s of flights is gonna stress my attempts to beef them up. Dremel removal of the black paint down to bare aluminum before 1, 2, 3 above will be a first step, if they are painted black.

-GG

[EDF-Jetpilot]

The 70 mm FW F9F Panther Jet mains have the same anti-torsion arm. Thanks Evan! I will be removing the arms and installing them on the SR-71 ASAP.

SKU FJ22111084

Available option until the SR-71 spares open for ordering if you are in a “gotta have” situation like I
am.

Update: Installed the Panther Jet’s anti-torsion arms on the SR-71. Perfect fit! I am in business again.

-GG

Photo of the Panther Jet’s main gear.

Great, I wish you luck! From the looks of it, it's exactly the same cast aluminum as the SR-71, just not painted black, not promising... but I don't want to dash your hopes and wish you good luck and a long life.