Anyone use foamboard for Mid-powered

[SRP Crew]

Has anyone had any success with foamboard on the fins?
I found some 3/16" thick. It's very light, but can it withstand some of those aerodynamic pressures we put on fins.

I've got 4 Tomahawk-style fins mounted on the tube but wonder about fin flutter at maybe 300 mph on max.
Just wondering...

 

[Pem Tech]

Will you be fiberglassing the foamboard?
If not, I would be more concerned about damage from handling, storage and landing. A few years ago I scratch built a 3" BT trans to 2.6" using PML phenolic called DEEP-SHT. Since the fins did not overhang the aft of the body tube I thought foamcore would be fine.
In this case, I was wrong....

The fins dent, crunch, wrinkle, bend and shed paint much to easily.

It is a 33oz. (dry) rocket flying on F40's - G64's and there has not been issues with fin flutter. When I rebuild her she will be lighter and have 1/8" ply fins.

Good luck with whichever your choose.

 

[Pem Tech]

Forgot to add the picture...
*DOH*

 

[rstaff3]

I have used the stuff a lot (lpr thru hpr) but have no data on flutter issues. This of course will depend on the form-factor. My experience agrees with Layne in that I've never had a problem on the upward direction, but almost always have some landing damage. Then. mine have mostly been heavy (overall) and/or draggy so speed wasn't really an issue. On my latest I'm experimenting with replaceable foam fins.

 

[Meat]

I used foamcore on a scratch build trash rocket I did . It did not hold up well at all after 3 launches the fins were crinkled pretty bad all three launches were good ones with soft landings . We wont mention the 4th launch where it tore off the lugs and went face first into a tree .

 

[SRP Crew]

Yes. the material is really destructable. That's the downside for sure. I haven't really got any place to do glassing right now, but that's in the near future.
I definitely agree with the responses on durability. It's not there with this stuff.

So, I'm making 4 "disposable rockets"...for let's just say experimental purposes, so these aren't meant to last anyways, just to get up and over once or twice depending.

So the main objective is getting the airframes to apogee. The foamboard is a lot cheaper then balsa and is really light and glues very well the tube. Also, if I wreck a fin or two, it's tremendously easy to fix. That's why it's got me thinking that this could actually work. I'm just worried they may go squirrely on the way up. Has anyone had vertical issues at variable speeds?

 

[KDRaven]

The last time I launched my 98% foamboard rocket it did great untill the G71-4R turned into a G71-1R and when one rocket went up and 5 peices came down I was reminded that I was going to have to rebuild it for the third time.
View attachment 2532
This photo was right before the delay went too short. It was 42" long and 4" square. It had been flown on E's, a G55, and finaly on a G71.
Yes foam bord fins do get beat up but they are nice and light and I have used them several times in LPR but only the once with a MPR bird.

 

[CharlaineC]

I have built odd rocks with it such at art appleworks priroty one and others with no issue. also in a large number of rockets its my centering rings.