SR-72 DarkStar, 1:20 Scale, design by FoamyDM

[FoamyDM]

I’m glad yours flew enjoyably. Mine was a handful. Maybe because the Top Gun version was purely designed to look cool, and didn’t actually go through any wind tunnel testing to see if it would be unstable.

Honestly if you took the rear spike off mine, it wouldn't make a difference. the Short wings lend to easy rolls. But it should be stable. the nacell bump ends up being a better-than-a-plate lifting surface. After 10s, @Matthew Sanders, did something shift in the plane, (battery or component). because that change from nice to... what happened here, is usually a shift int he battery. yours is small enough to make again easily enough. Continued luck.

 

[L Edge]

I finished mine! About to go try it! Hopefully it works! Will update! View attachment 227643
View attachment 227644 View attachment 227645 View attachment 227646 View attachment 227647

Are you going to rebuild?

 

[Matthew Sanders]

Honestly if you took the rear spike off mine, it wouldn't make a difference. the Short wings lend to easy rolls. But it should be stable. the nacell bump ends up being a better-than-a-plate lifting surface. After 10s, @Matthew Sanders, did something shift in the plane, (battery or component). because that change from nice to... what happened here, is usually a shift int he battery. yours is small enough to make again easily enough. Continued luck.

No battery shift. I had it very securely tightened. I didn’t notice it’s instability until after about 10 seconds or so because I was flying straight and level and didn’t attempt to move the control surfaces very much before that point when I initiated my first turn. Unfortunately you’ll just have to take my word for it because of the footage loss, although I plan to get replacement footage because...

Are you going to rebuild?

Oh yeah! Airframe #2 is already half built. Just waiting on a replacement battery (since my plane was stuck in that tree for 20 days, the battery was plugged in so it drained to 0% and puffed, so it’s now a bad battery.)
I’m surprised after getting rained on (hard rain, EVERY. SINGLE. DAY.) everything still works. Just had to clean out tree gunk from the EDFs and RX.

 

[L Edge]

MS:
The 72 is the same acting as the SR-71. In order to fly your bird, you need controlled rudder movement. So add differential thrust.
Your problems of turning is the same that I had designing my SR-72 and X-47B(no vertical or rudder at all).
Also doing right turns should be included.

You will find the designing of SR stuff and the Warthog(EDF version) are very tough projects.

How you launch it is another problem. Too steep, watch what happens. It took me awhile to solve right hand turns. The main overall problem is handling the yaw.

 

[Matthew Sanders]

MS:
The 72 is the same acting as the SR-71. In order to fly your bird, you need controlled rudder movement. So add differential thrust.
Your problems of turning is the same that I had designing my SR-72 and X-47B(no vertical or rudder at all).
Also doing right turns should be included.

You will find the designing of SR stuff and the Warthog(EDF version) are very tough projects.

How you launch it is another problem. Too steep, watch what happens. It took me awhile to solve right hand turns. The main overall problem is handling the yaw.

I’m already planning to add Differential thrust! Admittedly, I don’t use rudder as much as I should when flying, but maybe I’ll add a “coordinated turn” mix so the aileron movement also controls yaw.
So, are you saying it will turn left better than it will turn right? I typically fly in a left hand pattern, but leveling out of a bank n yank turn by rolling right might be a problem then if it dosent turn right very well. (Then again if it’s a dual EDF with everything symmetrical then there shouldn’t be an issue, right?)
In terms of taking off, I’ll most likely do the fixed gear method again. That worked incredibly well last time.
Thanks for the info!

 

[Matthew Sanders]

Update on my DarkStar. Just finished Airframe number 2. Just need to add servos and cut in the ailerons and it’ll be ready to go. Just added differential thrust, which is the first time I’ve done so, I might add. Looking forward to having that capability in flight.

 

[ConcordeSpeedbird1978]

I'd love a plan of This Darkstar when you complete it please Sir.

 

[FoamyDM]

I'd love a plan of This Darkstar when you complete it please Sir.

Good question. I hope before year end. I am finishing up two big projects. 1 is a hobby room relocate and organization. 2nd is the B5N Kate.

 

[L Edge]

Good question. I hope before year end. I am finishing up two big projects. 1 is a hobby room relocate and organization. 2nd is the B5N Kate.

Do you still have the model?

 

[FoamyDM]

Do you still have the model?

Get rid of such a beautiful bird?! No way. I have it right here.

 

[L Edge]

Get rid of such a beautiful bird?! No way. I have it right here. View attachment 240500

Are you going to adapt to EDF's?

 

[FoamyDM]

I was hoping to have an efficient fast bird with plenty of thrust. Of which there is plenty. I appreciate the interest. A 5" EDF is 127mm which is gets very expensive and battery intensive.