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

[Aros]

Some history on the M21 including a tragic end…

The Lockheed D-21 unmanned drone was launched at Mach 3 from a pylon mounting on top of the rear fuselage of an A12 Blackbird. The designation of the A12 then became an M21 with the D-21 installed. Two A12's were modified (#60-6940 and #60-6941) to carry the D-21 Drone. In June of 1963 a D-21 was mated to a mother ship for the first time. Actual first flight did not occur until December of 1964. After flying the Photo Reconnaissance mission, the D-21 flew to friendly territory and the camera was ejected from the D-21 Drone. The cameras were recovered in flight by a C-130 mid-air recovery system. The D-21 drone would self-destruct at a low altitude. Kelly Johnson, Lockheed Skunk Works Chief Engineer, cancelled the M21 program when a D-21 was launched into the area behind the cockpit of the M21 resulting in loss of the Launch Control Officer's life and loss of the aircraft. The D-21's then was mated to a B-52H Stratofortress (Project was called Senior Bowl). Five operational missions were flown in this configuration over China. Operations ceased due to political reasons, cost and difficulty of operation. The "Museum of Flight" in Seattle, Washington has the only A-12/Drone display combo in existence.

[Aros]

Got mine late tonight. Too tired to build her completely but what a presence. What a size. What attention to detail. Freewing nailed it. Can’t wait to build her completely soon.

[Husafreak]

C'mon someone fly it and report back, LOL. A flying buddy has his ready to maiden and I may be involved in that this Saturday. I've watched the MRC videos and it looks like it can handle a pretty high AOA and doesn't flare much, just a cosistent descent to touchdown at approach speed. Kind of like my FW F-104 90mm lands. I'm curious, does it have flaps?

[GliderGuy]

SUCCESS!!! 3 flights in freezing temps, but very light wind (about 5 mph).

Let me first state that I reserve the right to change up all the below as I get more experience. BUT, my first impressions are what you will also/probably experience.

Use this info to help prepare yourself mentally. And remember, as the throttle comes up on your maiden, to say, “Here goes EVERYTHING!”

SUGGEST you add clip-on RF chokes on the wires coming from each ESC as close to the ESC as possible. Put a choke on the wires going in to the fuselage. I also added a clip on choke by the green ferrite choke between the BEC and receiver. Much discussion is found in other forums about the benefits of RF chokes.

Be patient as I offer a few tips and observations before the flights are discussed.
- She makes wide turns on the ground. However, this means she isn’t twitchy on take-off or roll out. For tighter ground turns, switch to high rate (remember to go back to low rate).
- There was no tendency to crow hop. My 3 landings were OK, but not nearly smooth. Once on the ground, she sticks.
- With an Admiral 6000, pushing it all the way to the rear of the front compartment = Good CG for your maiden. She balances a “tiny” bit nose down with the gear down using my finger tips at the CG mark.
- When you decide to make your first flights, go someplace with a LONG runway. I WOULD NOT attempt your first flights on a short runway. You’ll need space to ease her out of ground effect and flair. She will probably try to float up on you, so having room to ease her down and not rush things is helpful.
- Put a dab of RTV silicon rubber on the bottom-rear of each jet nozzle. I managed a landing or two nozzle first. Makes a heck of a noise, but only minor scratches resulted. Also, put a dab of silicon rubber on the farthest rearward outer wing tip on the bottom. This is where the wing tip impacts the ground in a too nose high and not level landing. Saves getting scratched paint out there.
-Set some aileron EXPO. She rapidly responds to aileron inputs. You will want to tame this a bit. I made all 3 flights on low rate and no EXPO. Gonna adjust that before the next flights.
-She tracked “almost” straight during taxi. Thanks FW/MRC for paying attention to the small details.
-Add some clear coat over the decals. The edges began to lift after only 3 flights.
-Set the timer for 3:30 with a 6000 mAh battery. You will want to start your pattern at 3:00. All 3 flights ended with 3.8 V measured.
-Line up the inner control 3 mm ABOVE the horizontal line on the tail cone….at the rear edge. Then line up the outer control trailing edge with the inner control trailing edge.
-Gyro input open…defaults to GREEN (normal) mode. I only have a 6ch rig.

That’s long enough….next post is all about FLYING AN SR-71!!!!!!! Gotta go eat dinner…stand by!

-GG

[Aros]

Fantastic maiden report as usual GliderGuy!

Appreciate your detailed reports and analysis. I’m hearing reports that the throws need to be tamed. YES! You don’t want to fly this bird with high rates for any reason. Stick to low rates and minimal aileron throw. Pitch throw is fine but keep the roll throw minimal and she will be happy. In fact, if there’s enough people that complain about how over sensitive the recommendations are from the manual I can update it accordingly so please let me know if you have thoughts on that.

Got mine put together tonight. She is GORGEOUS!

[GliderGuy]

SR-71 FLIGHT REPORT….
Disclaimer / User experience may vary. LOL

Fairly sure after more flights and tweaking I will LOVE this plane. Soooo AWESOME looking in the air.

-Range check (150 ft she stopped responding) with xmitter on the ground and in low power xmit test mode. 30 ft is good enough. - check
-Verify the gyro is reacting properly - check
-Light wind - check
-Flight controls - check
-Timer set 3:30 - check
-Taxi a good distance down wind, turn around back toward me and HERE GOES EVERYTHING!!!!

I wanted to avoid yanking her off into a steep, high alpha situation. So…I let her run. She lifted with a typical amount of up elevator. Now she began a right bank and with neutral stick…a slight nose down attitude. Took me about 3 circuits to trim her out.
Once trimmed (not a lot), I concentrated on feeling her out.
She felt best at 3/4 throttle like the F-4. 1/2 throttle seemed a bit sluggish. I need to LEARN about this because 3/4 throttle = short flight.
Again, the overhead passes look AWESOME!
Elevator sensitivity is about right. But after 3 “unsteady” approaches, I’m gonna add EXPO to the elevator, too. Can you say, “PITCHY APPROACHES?” LOL
It was easy to keep her from not getting too far away, but I am used to hot rodding around the sky with the ever so fast PJ-50.
At one point, I made a too steep turn, and she reversed direction in about 80 yards diameter circle. That caught me off guard. She will turn TIGHT!
Cruising around, you will notice how sensitive to roll inputs she is. EXPO needed.
No problem staying oriented. Of course, at a distance from the side, a 45 degree bank either left or right is gonna look the same. THINK about your control inputs. What did you just tell her to do? Then if correcting a bank gets worse, do the opposite!
Lowering the wheels ADDS A LOT OF DRAG! Every time I extended the gear, I ended up at 3/4 throttle to “feel” right. THERE WAS NO PITCH CHANGE when raising or lowering the gear.
On base leg, reduced power to 1/2 throttle. Then 4 more clicks less power on final. Now you’ve got to concentrate. Without EXPO on the elevator, she’ll get pitchy on you. Working on attitude and ground impact avoidance, she landed a bit hard. NO ATTEMPT TO START A CROW HOP! She landed and stuck!
The second take-off showed more left aileron trim was needed. Then I had some REAL fun cruising about. Low passes will be fantastic.
The second landing was a terrible approach. A gust hopped her up outa ground effect and into a nose high and moving sideways over the ground and TOO SLOW situation. Adding a bit of power prevented a hard drop in. What was good….She stayed in control and did not stall or drop a wing. Touchdown was jet nozzle bottom first, but she stuck and stayed straight. No crow hop.
The 3rd take off was typical EDFish. Stayed straight and nice climb out. PLENTY of power!!! I also ended up with about 2 mm of left rudder trim. More fun cruising about and learning her control characteristics.
Focusing VERY hard on the 3rd approach pitch control, I passed by way too high (head high) much above a normal approach for me. But I had plenty of pavement ahead, so I worked on the landing without rushing. FINALLY, a good landing!!!
Will she be hard to land…NOPE! Once the right speed/attitude/throttle settings are learned along with some EXPO, landings will be nice.

6 ch = no chute, no reverse, no mode change for the gyro. A ham radio friend said pull these unused leads from the control box to be safe.

Have fun! Report your flights. Share your tips.
What a unique experience the SR-71 will be.

Any buyer’s regrets? Absolutely None!

-GG
RC Experience level: MRC - P-38, F-4, AL-37, B-2, MIG-29, PJ-50, A-10, and a touch of SR-71

[Aros]

Again, GREAT report! Love the detailed analysis including the warts and nuances that come with flying such a iconic and challenging bird!

My many years of experience comes from the 64mm LX version and while you can't compare these two models head-to-head obviously, there are flight characteristics that should be similar.

I have said this many times over the years...It took me a long time to tame that bird and it didn't occur until I figured out that the aileron throws truly need to be dampened. Like subtle. Pitch throws can be somewhat aggressive but at the end of the day it comes down to this:

To fly the SR-71 Blackbird scale and successful you need the following:

• Make sure the CG is dead nuts. Don't waver too far from it.
• Reduce the aileron throw more than you normally would.
• Be liberal with your expo. Don't be afraid to explore higher values than normal.
• Treat her like a race car. She wants to "fly around the track". Sure you can do rolls, etc, but this bird is meant for scale flight.

Lower roll rates, decent pitch rates. Don't fly her like some aerobatic mode. Do these things and you will be happy her for quite some time!

[GliderGuy]

FYI…For those of you who may not have seen all the prior discussions, in other forums, on the benefits of adding RF chokes, you can buy them on Amazon. No need to rehash those prior year discussions here.

Search Amazon on “Clip-on RF Chokes”.

Place one on each ESC as near the ESC as you can. Clip one on all 3 of the wires (buy a variety pack and one size will fit around all 3 wires at once) which run into the fuselage.

I add a zip tie around each choke to secure it closed.

Bottom line…I lost a few EDF planes due to loss of control before I began to add them. Since I now add RF chokes to every high power EDF jet’s ESCs…I have not had a single loss of control event. Enough evidence for me….

-GG

[Shaun Evans]

Welp,

Just pulled the trigger on this after seeing that video of it popping a wheelie on landing!

Going with single turbine, though I wonder how much extra length I'd need on that chute cord!

Should be fun! I'll pull the EDFs and ESC and list em for sale if anyone is interested on discounted e-fan stuff.

[ElCid]

Welp,

Going with single turbine, though I wonder how much extra length I'd need on that chute cord!

.

Sarcasm? Not sure you will get this airborne on one fan...

[Aros]

I had a snafu with my parachute during the binding process. It popped out as soon as it was bound. No biggie. However, I was unable to close the hatch back up. It would not "bite" and click and stay down. I had my girl take a look at it and she figured out the aft section of the mechanism needed to be explored. We opened it up, looked at the white plastic piece that "bites" onto the hatch that allows the mechanism to open and close, and she determined that one of the screws didn't look as screwed down as the other one. Sure enough, I had to turn several twists until both screws were fully secured and tight. Once we tried again, it clicked right down and is good to go!

Something to consider for those of you who run into the same issue.

[GliderGuy]

Aros…brings up an interesting thought experiment. What if the chute pops out in flight?

2500 hrs spent flying a full scale ASW-12 sailplane which had only a 6 ft diameter drag chute for glide path control (no dive brakes or spoilers) allow me to surmise the following…

First…don’t panic. Most important KEEP YOUR SPEED UP! I plan to react like this: Immediately go to full throttle and begin an immediate turn back toward the runway. Keep a nose down attitude. Worst thing you can do is bleed speed and get too slow. Adjust throttle and attitude for a good descent rate that’ll get you to the runway or to a landable area. I suspect with full throttle, she will initially do fine. As you get close to the ground, avoid a normal throttle reduction. Keep about 25 percent power. Remember, she’s gonna bleed speed rapidly once you flare. Beyond this, make a normal landing.

Someone at FW or MRC who has some hours on the SR-71 should get high over the field and try it. Then post a “how to” for the other owners.

-GG

[GliderGuy]

PS I’ve decided to put a tiny bead of RTV silicon rubber strategically placed to ensure the chute doesn’t pop out accidentally, since I’m not using it until I get a new radio. The cured rubber can be easily removed with a razor knife when the time comes. One less thing to worry about.

-GG

[GliderGuy]

Woo Hoo! 4 more fantastic and FUN flights at sunrise before the wind came up…24F brrr.

NAILED IT! 50% expo on both the aileron and elevator channels is the sweet spot. She feels GREAT and behaves as you’d expect. Not pitchy on the approach at this expo.

She feels really good at 75% throttle, but good at a bit more than 50%, too. She needs added up elevator in the turns…especially steeper banks. What a presence in the air and on a lower height fly-by!!!!

Fairly normal EDF approach. Plan it like you do your other EDFs. I was high and fast on one base leg and chopped the throttle 0 thrust. Glide on final and then just a touch of power to reduce the sink rate. She did fine.

All were normal main-first touch downs. And she sticks without bouncing.

Right now, I’m staying with 3:30, but will experiment more at lower power cruise to get to 4:30…maybe. She feels so solid at 75% power, lower throttle will take some getting used to.

Get your CG right and 50% expo dialed in. You are going to LOVE this RC plane. Thank you FW/MRC for putting this unique beauty plane in our hands!

-GG

[EDF-Jetpilot]

C'mon someone fly it and report back, LOL. A flying buddy has his ready to maiden and I may be involved in that this Saturday. I've watched the MRC videos and it looks like it can handle a pretty high AOA and doesn't flare much, just a cosistent descent to touchdown at approach speed. Kind of like my FW F-104 90mm lands. I'm curious, does it have flaps?

A delta like the SR-71 can't have flaps... where could it?

[Aros]

Someone at FW or MRC who has some hours on the SR-71 should get high over the field and try it. Then post a “how to” for the other owners.

I will gladly borrow yours to try it out!

[Aros]

Woo Hoo! 4 more fantastic and FUN flights at sunrise before the wind came up…24F brrr.

NAILED IT! 50% expo on both the aileron and elevator channels is the sweet spot. She feels GREAT and behaves as you’d expect. Not pitchy on the approach at this expo.

She feels really good at 75% throttle, but good at a bit more than 50%, too. She needs added up elevator in the turns…especially steeper banks. What a presence in the air and on a lower height fly-by!!!!

Fairly normal EDF approach. Plan it like you do your other EDFs. I was high and fast on one base leg and chopped the throttle 0 thrust. Glide on final and then just a touch of power to reduce the sink rate. She did fine.

All were normal main-first touch downs. And she sticks without bouncing.

Right now, I’m staying with 3:30, but will experiment more at lower power cruise to get to 4:30…maybe. She feels so solid at 75% power, lower throttle will take some getting used to.

Get your CG right and 50% expo dialed in. You are going to LOVE this RC plane. Thank you FW/MRC for putting this unique beauty plane in our hands!

-GG

Another nice report, thank you! Funny, by instinct alone I put my dual rates at 50% expo before reading this post. Just "felt right". I have the recommended throws for now. CG will be manufacturer's recommended.

Compared to the wildcat that was the LX version, this bird looks like she flies much more tame.

Hearing someone had their EC5 connector melt or something on the RCG thread. Now some folks are worried about needing to switch out their connectors. You have flown yours several times on a single 6S I assume without any issues?

Evan D has had a lot to say about the matter and would love for his expertise to weigh in here.

[GliderGuy]

Here’s my experience…male (airplane side) EC5 melting. It first happened with an AL-37. Investigating…it was determined the contact screen/spring had deteriorated and became highly resistive. The P = IxIxR heat melted the blue plastic.

The fix = new EC5 or replace with the split barrel flower petal type (no contact screen).

Mind you it took lots of flights before the EC5 got to this point of deterioration. Any of the single-battery 70 mm fan ships “might” have this happen. Here’s a summary from my ships: AL-37 = once, PJ-50 = 0, B-2 = 0, SR-71 = 0, A-10 = 0, F-4 = 0, MIG-29 = 0.

It’s no secret that some of these birds have over 1,000 flights, so the EC5 melting issue isn’t common. Otherwise, I would have seen it more than one time.

If you don’t like the split-barrel flower petal type EC5, and each type has its detractors, then frequently inspect with a bright light the condition of your connector’s barrel spring/screen. Each connection “spark” blows away some of the connection spring/screen. This type connector will succumb to this spark effect eventually.

Now to go see what type connector design the SR-71 has. It has the spring/screen type connector.
Added note: Even early on, the solder or braze between the inner shaft and the spring/screen could fail making for a high-resistance connection = heat and melt early in its life.

-GG

[Evan D]

The issue of over heated/ melted EC5's has happened a few times over the years and as far as I can tell is caused by one type of male pin on the connectors. There are two types of EC5 pins, see the picture attached. The left is what I call split type and the right "banjo". The split as GG notes is a much more robust type.

There has been ONE reported case of the issue with the SR71 and in my opinion it is caused by the amount of power, Amps, drawn by two fairly powerful fans running off a single battery through a single connector. Each fan is capable of pulling 80+Amps so a freshly charge battery may supply 150+Amps (there would be some dragging down of the battery at this level of current). This is more that even a 8S 90mm EDF would draw so we are seeing this for the first time on FreeWing planes.

So what can we do? Well first, it is going to be rare and probably when someone has a good battery, more than likely a high C or HV battery that can supply the amps to do the damage. And probably when someone flies long periods of full throttle. And as GG notes repeated connecting of the connectors is deteriorating the springy thin banjo part of the pins so after time you may develop the issue.

What to do?

First, if you ever feel your connector, any connector, is hot find out why, it means there is electrical resistance in the connection and that will only get worse.

Also again, this may never be a problem on your plane. Just reducing timing or limiting full throttle usage to a few short fast passes may prevent it from happening. Going to better connectors would be a better way. If you are happily using EC5s and have a lot of batteries with them changing the male pins in the ESC connector with the split type pin should also work. And of course going to larger connectors like AS150's would solve the issue though I think that is over kill, especially if you have a lot of batteries and planes with EC5's.

Another thing is the spark when connecting the battery, that will wear out your connector and adding an anti-spark in line could also help, I would say not prevent but help.

Another choice would be to run two batteries in the SR, one to each ESC so each would see the 80A instead of the full 150A and this may be a great choice for some that have a supply of 6S 3300mAh but would require splitting the battery leads from the two ESCs and soldering connectors and some extensions to the wires. This could have the side benefit of larger battery over all for longer flight times and as the SR has two bays I think some may already be thinking of doing this.

[Evan D]

GG, on the "banjo" type ones I have the springy banjo part is not soldered to the pin part and can roll on it. Maybe you have some where a little solder got on soldering the pin on the wire or something?

Here’s my experience…male (airplane side) EC5 melting. It first happened with an AL-37. Investigating…it was determined the contact screen/spring had deteriorated and became highly resistive. The P = IxIxR heat melted the blue plastic.

The fix = new EC5 or replace with the split barrel flower petal type (no contact screen).

Mind you it took lots of flights before the EC5 got to this point of deterioration. Any of the single-battery 70 mm fan ships “might” have this happen. Here’s a summary from my ships: AL-37 = once, PJ-50 = 0, B-2 = 0, SR-71 = 0, A-10 = 0, F-4 = 0, MIG-29 = 0.

It’s no secret that some of these birds have over 1,000 flights, so the EC5 melting issue isn’t common. Otherwise, I would have seen it more than one time.

If you don’t like the split-barrel flower petal type EC5, and each type has its detractors, then frequently inspect with a bright light the condition of your connector’s barrel spring/screen. Each connection “spark” blows away some of the connection spring/screen. This type connector will succumb to this spark effect eventually.

Now to go see what type connector design the SR-71 has. It has the spring/screen type connector.
Added note: Even early on, the solder or braze between the inner shaft and the spring/screen could fail making for a high-resistance connection = heat and melt early in its life.

-GG