Rear-Ejection Heliocopter

[SRP Crew]

On the way to work recently, I had this wild idea. I've since drawn up the assembly and wonder if this has ever been done. There are some cp/cg issues but It is starting to look realistic.

Anyone have any ideas they can share.

 

[lessgravity]

Yes - actually built one last year. Mine worked well but I lost it in a tree. I have seen pictures of others.
Mine had the copter blades hinged around the motor area. The fins set on top of the blades.The nose cone had "hold downs" that held the blades in the launch position. When the nose cone was blown off the blades were free and opened toward the rear.With the extra hardware of hinges and stuff aft the nose cone needed a bit of weight to keep it stable. I've also seen versions that separated the tube above the motor mount.

Of course there is always room for innovation.

 

[SRP Crew]

Okay!

It's not a cooky idea after all then.
Here's the concept as drawn up. Let me know what your thoughts are.

Cheers

 

[lessgravity]

I think this design will totally work.
Reminds me of the Kopter designs but rear ejection instead of forward. I would suggest creating folding blades like a Rose-a-roc in order to create more blade area. Take pictures so I can highlight your approach on my Copter Recovery Guide.

 

[SRP Crew]

Wow, you have a lot of copter info on your link. I'll take some note of the blade examples you have. The front end approach is definitely common out there.

Yet the whole purpose of this heliocopter design is to conceal the blades going up. Yes, you're right, the blades on my diagram are not true looking. I think they're too thin and could use curvature/width etc. I may run into some roadblocks with them as the learning curve goes to work.

I've got till spring to mock up some parts and find my connections. I do have a good feeling about this one though (not in a cocky way), it's that rocket sense kicking in for once I guess.

I'll take some photos of this process as it becomes more of a reality.

Thanks for your input. greatly appreaciated.

 

[Micromeister]

Rob Edmonds had a 3 blade/fin HD model prototype flying in 91-92 time frame. I have it on VHS tape but haven't converted it yet. I don't recall what he called it but it was very interesting.
Rotors folded up along the sides of the tube and hinged down at ejection with the fins forming the rotor-stop disc. worked very well, I seem to recall it was flown at Novaar's "1/4 licks" 1/4A open meet back then.
I have a photo somewhere but can't lay my fingers on it. Maybe Rob will see this thread and respond.
it was a very unique design.