Project Un-flyable/Tacit Blue (90mm edf)

[L Edge]

I see that the wing location is not far enough forward and to me it is out of scale. To me, there should be a bigger gap between the trailing edge of the wing and your V-tail. That means the CG and CP needs adjustment just like Piotrsko stated. Wing should be moved forward.

I fly a SR-71 with a pair of EDF's 64 and with the long nose, yes, yaw is a problem. The V-tail should solve yours Pitch is another problem for if that long nose goes down, it either starts oscillating badly or just head for the ground especially in a turn.

You took on a tough project being a big long box.

 

[the rc project]

I see that the wing location is not far enough forward and to me it is out of scale. To me, there should be a bigger gap between the trailing edge of the wing and your V-tail. That means the CG and CP needs adjustment just like Piotrsko stated. Wing should be moved forward.

I fly a SR-71 with a pair of EDF's 64 and with the long nose, yes, yaw is a problem. The V-tail should solve yours Pitch is another problem for if that long nose goes down, it either starts oscillating badly or just head for the ground especially in a turn.

You took on a tough project being a big long box.

Agreed, The wings do need to come forward to be more scale. I expect to crash many times(crash investigation is kinda the best part🤷‍♂️), downscaling an already unstable plane is tricky. This is not a practical project, absolutely no purpose but to fly a goofy looking whale plane! To move the wings on the large model forward might not be worth(just build another) as for the little one I will do some tinkering.

 

[the rc project]

Nose is a bit way too long and is destabilizing. Probably on the verge of being uncontrolled. There was a thread with some college students last spring that had a similar design and it flew decent until they tried to turn crosswind and crashed. If you look at the cele (latest turbo go fast passenger ship) the rudder and dorsal is freaking huge. Iirc, you need to get the COP behind the CG.

“A bit way too long”😂😂 well yes... “on the verge of being uncontrolled” no it is entirely uncontrollable... I’m working on getting the equipment to make a 90mm model working right, I know it can work as a small scale showed pretty good flight characteristics(subsequent brownout resulted with a tree climbing challenge) I will look into the cele!

 

[leaded50]

you will get lift on nose, because of design... i think i would pushed the wing a touch more to nose. Distance between wing and tail stabilizer have much to say on longitudinal stability .

 

[Piotrsko]

“A bit way too long”😂😂 well yes... “on the verge of being uncontrolled” no it is entirely uncontrollable... I’m working on getting the equipment to make a 90mm model working right, I know it can work as a small scale showed pretty good flight characteristics(subsequent brownout resulted with a tree climbing challenge) I will look into the cele!

Too many variables that are not stated to say if it's uncontrollable or not. Didn't establish if you were flying too slow or what not, so I thought I'd be generous. Sheesh.

 

[the rc project]

weather isn't good for flying for the next few days but when it clears up i plan on showing some videos of some flying action!(don't hope for much these flights don't last long) hopefully i can better show what's going on.

 

[L Edge]

weather isn't good for flying for the next few days but when it clears up i plan on showing some videos of some flying action!(don't hope for much these flights don't last long) hopefully i can better show what's going on.

Looked at my notes for my SR-71and will suggest the following when you fly.

1) Roll is super-sensative so only allow small deflections.
2) Launch horizontal so nose doesn't get to up or nose down. Try to keep it straight to gather speed.
3) Yaw requires you to be fast to respond and hold the rudder as it goes forward.

Try to fly it low. Less kinetic and potential energy will reduce crashes. Here I was trying to work out CG and yawing. Took me 6 flights and had no damage. I prefer wind because airflow is over the wing even before you throw.

If you are going to redesign, will give you a couple of approaches to try.

 

[L Edge]

If you need to add elevons or rudder to an EDF flow, do it outside the tube so it flow goes to the atmosphere. Do not put inside the tube because it will not be very effective,(Ask me how I know). Outside, had good control.

This was for my VTOL project that got sunk due to poor spooling up and down and not fast enough for the gyro to handle. After 6 years, VTOL has kicked my butt in 3 different designs. Still working on getting it right. Don't give up on yours.

Rudder was controlled by seperate servo.

Had servo mounted so it could handle ailerons or elevator.

 

[the rc project]

If you need to add elevons or rudder to an EDF flow, do it outside the tube so it flow goes to the atmosphere. Do not put inside the tube because it will not be very effective,(Ask me how I know). Outside, had good control.

This was for my VTOL project that got sunk due to poor spooling up and down and not fast enough for the gyro to handle. After 6 years, VTOL has kicked my butt in 3 different designs. Still working on getting it right. Don't give up on yours.

View attachment 181984
Rudder was controlled by seperate servo.


View attachment 181985
Had servo mounted so it could handle ailerons or elevator.

Now I get it. Makes sense

 

[the rc project]

I never really followed up here. This plane really didn’t like flying, maybe 4 full flight attempts were made all with small changes that couldn’t eliminate the lack of control. Here are some pictures from the some of the videos, the CP is too far forward and the tail starts to overtake the nose, once the flat side of the fuse get into the airstream it parachutes and flips. The two pictures are from different flights. It just so happens it went the same way. The CG was moved about 4 inches total in the testing to try to get it off the ground. It would fly straight for a few feet and then once it got a few degrees skewed it would get worse and worse. May be revisiting this project with a Gyro. Still think it’s one of the coolest planes ever