Aluminum HoneyComb Fins ??

[gregzo]

Has anyone played with this stuff to make any rocket fins? I made a 12" rocket with 3/8" Aluminum Honeycomb. I machined into the honeycomb sandwich to remove the honeycomb by 1/4" and left the skins in tact. Then I took 3/8" x 1" fiberglass stock and machined down one edge by 1/16" x 1/4" per side so it would slip into the honeycomb material. The other edge was machined into an airfoil-ish. The tip cord got squared off fiberglass fairings. I bonded the edge fairings into the fin stock with 3M DP420 Industrial Epoxy. The fins are 20" on the root edge and 16" span. They are stiff as all get out. They seem pretty light for their size...but I'm not sure just how much I saved in weight.
It flew on an L930 Loki White and did great. I was worried about the whole thing coming apart in flight. The fin are carbon fiber strip re-inforced to the motor tube and to the ID of the body tube. It is a short rocket - only 48" of body tube total. I can put up to an AT M1939 in it...that should test the fins!!!

I'll post some pics in a bit.

 

[Micromeister]

Not sure if the HPR folks have changed their building requirements or not, but model rocket construction prohibits the use of metals as structural parts, airframes and fins.

that said I'd think you can get the same 3/8" honeycomb in several thickness phenolic material. Once bonded to your outer covering laminate they are as stiff as any Aluminum honeycomb We've used and generally produce Laminated panels with about 1/3 the mass. Airfoiling might be a little testing but I'm sure it could be done. My Work make tapered thickness sign panels with the stuff. Once Laminated on one side it machines much like plastic. It's getting a little harder to find these days but a bit of on-line searching may find an outlet near your neck of the woods

Hope this helps.

 

[ben_ullman]

Greg was that the L you flew at LDRS? If so I saw the rocket at the pad but not upclose. What kind of altitude did you get one L? Id love to put a hot blue or Red load in that!

Ben

 

[5x7]

Has anyone played with this stuff to make any rocket fins? I made a 12" rocket with 3/8" Aluminum Honeycomb. I machined into the honeycomb sandwich to remove the honeycomb by 1/4" and left the skins in tact. Then I took 3/8" x 1" fiberglass stock and machined down one edge by 1/16" x 1/4" per side so it would slip into the honeycomb material. The other edge was machined into an airfoil-ish. The tip cord got squared off fiberglass fairings. I bonded the edge fairings into the fin stock with 3M DP420 Industrial Epoxy. The fins are 20" on the root edge and 16" span. They are stiff as all get out. They seem pretty light for their size...but I'm not sure just how much I saved in weight.
It flew on an L930 Loki White and did great. I was worried about the whole thing coming apart in flight. The fin are carbon fiber strip re-inforced to the motor tube and to the ID of the body tube. It is a short rocket - only 48" of body tube total. I can put up to an AT M1939 in it...that should test the fins!!!


I'll post some pics in a bit.

Greg,

Robert DeHate's fat boy upscale used them, he laminated the aluminum honeycomb with CF and edged it with CF arrowshafts, which he said he tapped into the aluminum edge with a hammer to seat it before gluing them on. The fins survived his massive N cato. Neat Idea!

 

[5x7]

Has anyone played with this stuff to make any rocket fins? I made a 12" rocket with 3/8" Aluminum Honeycomb. I machined into the honeycomb sandwich to remove the honeycomb by 1/4" and left the skins in tact. Then I took 3/8" x 1" fiberglass stock and machined down one edge by 1/16" x 1/4" per side so it would slip into the honeycomb material. The other edge was machined into an airfoil-ish. The tip cord got squared off fiberglass fairings. I bonded the edge fairings into the fin stock with 3M DP420 Industrial Epoxy. The fins are 20" on the root edge and 16" span. They are stiff as all get out. They seem pretty light for their size...but I'm not sure just how much I saved in weight.
It flew on an L930 Loki White and did great. I was worried about the whole thing coming apart in flight. The fin are carbon fiber strip re-inforced to the motor tube and to the ID of the body tube. It is a short rocket - only 48" of body tube total. I can put up to an AT M1939 in it...that should test the fins!!!

I'll post some pics in a bit.

Greg,

Robert DeHate's fat boy upscale used them, he laminated the aluminum honeycomb with CF and edged it with CF arrowshafts, which he said he tapped into the aluminum edge with a hammer to seat it before gluing them on. The fins survived his massive N cato. Neat Idea!

 

[Binder Design]

Not sure if the HPR folks have changed their building requirements or not, but model rocket construction prohibits the use of metals as structural parts, airframes and fins.

You are correct as far as model rockets go.

Ductile metal can be used in HPR if the flight stresses require it. Even if composites can withstand the flight stresses, it ablates at mach numbers exceeding about mach 2, making aluminum an attractive choice. It is a common sight at BALLS to see metal fins cans and entire rockets made from aluminum.

Mike Fisher

 

[BHP]

Yep. I just glued some split wooden dowels on the edges of the honeycomb boards. That aluminum is so thin I'd think it's less of a problem than fiberglassed fins when striking anything.

Here's my upscaled BLU-97 on an N3200 RX motor a few years ago. The fins held up just fine.

 

[Grif Ingram]

I used to work in the design office of an aircraft interiors company, and we used a lot of "Fibrelam" nomex honeycomb cored, fibreglass skinned board. The literature from Ciba-Geigy (now Hexcel) showed how this material could be used like cardboard (it came in 0.4 inch and 1 inch thick) and how fins had been made for a missile by bending it around to form an angular airfoil shape. This should be possible with other sandwich constructions - they used to do non-aerospace versions, too, which were cheaper, or try the "Aircraft spruce and Speciality" catalogue!
Grif