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

[GliderGuy]

Finally got around to checking the post flight cell voltage. The 10 flights yesterday were all made on brand new (first flights on them) Admiral 6000 mAh batteries.

1) Timer = 3:00
2) Gear down and upwind entry started at 1:30 remaining
3) Post touchdown timer showing about 20 sec (so a 2:40 flight)
4) Mix of throttle from 100% take-off to 50% to 75% cruise…no 100% used after the initial take-off.

Most cells measured 3.9V.

So, I’m gonna change my timer to 3:30 and adjust my pattern entry time based on throttle management for any given flight. For an almost total 50% throttle flight after take-off, getting to 4:00 might just be possible.

Also, the stock EC5 connector did not get warm or hot. I still plan to change it to a split barrel type ASAP.

-GG

[GliderGuy]

Anyone know if the EG01 can be used for steering as well? Just Y into the RUD maybe? I usually install the Assan AG61 in all my EDFs but I don't have an extra for this one and could not find anything in the manual.

Hi Skosh25…I know lots of folks love to use steering gyros, but in my experience…kinda overkill for the SR-71. She tracks very straight even after some not-so-good landings while learning her. No steering linkage adjustments needed, so far.

Anybody else have a comment on the bird’s ground behavior?

-GG

[GliderGuy]

Here’s a good color match for the SR-71…

spray can

TAMIYA COLOR TS-29 SEMI GLOSS BLACK

-GG

[Skosh25]

Hi Skosh25…I know lots of folks love to use steering gyros, but in my experience…kinda overkill for the SR-71. She tracks very straight.

Anybody else have a comment on the bird’s ground behavior?

-GG

.

That hasn’t been my experience so far GG. Have had to manually adjust the steering linkage after every flight.

[F106DeltaDart]

Word of warning to anyone who wants to replace the pilot figures… Tried to take off the canopies yesterday. The rear canopy came off with a bit of work just as you would expect. The front canopy, however, cracked almost immediately right down the center. It appears to be made of a thicker and stiffer plastic that makes it more brittle. And of course, there aren’t any parts in stock yet. Guess I’ll be waiting for the spares to come in..

[Aros]

Sorry to see that F106DeltaDart. I don't know if we plan to carry the canopies as their own spare parts to be honest. If enough customers are wanting to switch out pilots maybe it's something they will consider?

[F106DeltaDart]

Sorry to see that F106DeltaDart. I don't know if we plan to carry the canopies as their own spare parts to be honest. If enough customers are wanting to switch out pilots maybe it's something they will consider?

There is a spare parts listing for it, so I hope so.. Just need to wait for stock now.

[GliderGuy]

At least on calm days…maybe this is the way to land her short. Impressive! Need to experiment up high first.
No claim to the video’s authenticity is made. Attempt only if you decide it’s safe. So far, I haven’t come close to doing this. I’ve been landing like the AL-37…about 4 clicks of throttle on final until round-out.

https://m.youtube.com/watch?v=s9pQ6LIorV8

-GG

[Aros]

There is a spare parts listing for it, so I hope so.. Just need to wait for stock now.

Yeah I forgot I added that spare part, lol! Total brain fart. The latest estimates are early March but they are verifying exact ETA.

[Aros]

At least on calm days…maybe this is the way to land her short. Impressive! Need to experiment up high first.
No claim to the video’s authenticity is made. Attempt only if you decide it’s safe.

https://m.youtube.com/watch?v=s9pQ6LIorV8

-GG

I believe that video shows Jon (Two Brothers RC) at his well aft of recommended CG flights, not totally sure, plus of course it's slow motion obviously. For me personally I am sticking to recommended CG, at least for my initial flights.

[GliderGuy]

Hi Aros, Time to put the FW re-design team to work.
After 21 flights, GG has uncovered the first design weakness.

The plastic expansion fork/anti-torsion arm on the nose gear is too weak. It MUST be made stronger! The arm snapped. Of course, no steering after that, and when I lifted the bird, the wheels+shaft fell out.

This is going to require some thought as to how to fix it and get the bird going again before spare parts become available.

I’ll start to engineer a solution this evening. Stay tuned. I’m gonna look at a carbon fiber solution.

I have faith your team will come up with a more robust solution. If it must be plastic, then make it a solid piece without any mold cut-outs. The thin molded cut-out area is where it snapped.

So far, other than this, the bird is a solid, robust design. Reinforce yours BEFORE it breaks!
The black line shows where it broke.

-GG

[GliderGuy]

Temporary fix. I will sand it smooth once the Foam-Tac cures.

Basically, I built a carbon fiber box around the weak nose gear expansion fork/anti-torsion arm.

Suggest you reinforce yours before it breaks. Easier now than after it breaks.

-GG

[GliderGuy]

Update…JB Weld wouldn’t hold. Cleaned it all up and am trying Foam-Tac. It will withstand fracturing better than epoxy. Basically, a sheet of carbon is being glued to the top and bottom flat faces of the anti-torsion arm which “cover” the area of the fractured plastic expansion fork/anti-torsion arm.

Whatever you might engineer, a suggestion is make your anti-torsion arm stronger BEFORE it breaks. It is a spare part on MRC, but this part isn’t shipping, yet.

-GG

[EDF-Jetpilot]

Anyone know if the EG01 can be used for steering as well? Just Y into the RUD maybe? I usually install the Assan AG61 in all my EDFs but I don't have an extra for this one and could not find anything in the manual.

I'm not a fan of steering gyros on the nose wheel, but the B2 is almost impossible to control on the ground in crosswinds without one. But since the SR-71 is much longer than an F-16, I don't think it's needed here. My EDF jets don't usually fly completely straight on the ground, but you can easily correct that during takeoff. I love gyros in the air, but I don't need them on the ground, except for the B2. The longer the wheelbase, the less a nose wheel gyro is needed and vice versa. That's simple physics in my eyes. But to each his own, as far as I'm concerned you can mount a nose wheel gyro on the SR-71 too, I think that's a bit excessive.

[Evan D]

Look at the one on the 70mm Panther main struts.

Update…JB Weld wouldn’t hold. Cleaned it all up and am trying Foam-Tac. It will withstand fracturing better than epoxy. Basically, a sheet of carbon is being glued to the top and bottom flat faces of the anti-torsion arm which “cover” the area of the fractured plastic expansion fork/anti-torsion arm.

Whatever you might engineer, a suggestion is make your anti-torsion arm stronger BEFORE it breaks. It is a spare part on MRC, but this part isn’t shipping, yet.

-GG

[GliderGuy]

Thanks Evan!!! Ordered and will see if it fits. Appreciate your help!

I gave my attempted fix a gentle test this morning. The Foam-Tac isn’t quite cured hard, yet. But, it seems like it is going to work. There is good adhesion to the plastic and carbon sheeting.

Landing stresses will tell all.

-GG

[Evan D]

Good luck GG, you'll figure it out for sure.

[GliderGuy]

Looks like a fairly easy 3DP fix, with the weak points beefed up.

Go for it…if you have a 3DP which I don’t. That’d be great if someone would design the improved version and share the 3DP files here.

-GG

I didn’t think about a 3DP solution, since I don’t have one. Thanks for being on top of it!

[Aros]

I’ll reach out to our Freewing liason so he can look into this issue. Thanks for letting us know!

[ElCid]

I wouldn't hope for that, because in my opinion it's clearly not a grass runway aircraft... that wouldn't be appropriate for the species and it's certainly not fun to fly on grass on a regular basis. You'd be better off looking for something that can fly on grass, like an A-10, MIG-29, MIG-25/31 or something like that, that will definitely make you happier. sorry for my direct answer to you. You can also hang this beautiful thing from the ceiling, this machine looks very good there too. Of course, only if you buy it and then don't want to fly it on grass.

Someone will try it they always do. Hell, the b2 flies off grass just fine and I have all of the planes listed and then some.