Laminating Balsa Fins?
Burt Holyfield
paper and would like some more info please.
#1. What type of paper do you use?
#2. What type of glue (white, CA, of epoxy)?
#3. How does this compare to replacing the balsa with basswood?
I've got a dozen Estes rockets with broken fins, from not to soft but not
hard landings, to be replaced and I am wanting to try something to stop
this. Some of the fins are broken at the body tube and others are in the
middle of the fin.
Any and all recommendations are greatly appreciated.
Burt Holyfield
DAL
I'll use scrap or unwanted pages from my printer
2) I use medium cure (gap-filling) CA. I run ribbons of CA on the fin,
spread it over the entire side of the fin with a scrap piece of balsa,
place the paper on the fin, and then add a layer of CA on top of the
paper in order to make sure it's saturated. I then wipe the fin
quickly with a paper towel in order smooth the still-wet CA.
After the CA dries, I flip the fin over and cut the paper along the
edges of the fin with a sharp X-acto knife. I then repeat the whole
process for the other side.
I airfoil the fins after this process is complete.
I'm amazed at how strong the fins become and how easy they are to sand
to a very smooth surface. I find this easier than switching to
basswood since I don't have to cut out entirely new fins.
In article <AZHR5.13930$7P6.1...@typhoon.midsouth.rr.com>,
Sent via Deja.com http://www.deja.com/
Before you buy.
Jim Z in VT
Burt Holyfield wrote:
> I have read a couple of post talking about laminating balsa fins with
> paper and would like some more info please.
>
> #1. What type of paper do you use?
>
> #2. What type of glue (white, CA, of epoxy)?
>
> #3. How does this compare to replacing the balsa with basswood?
>
opinions here I'm sure. But what I've been doing for a while now is
laminating them with standard printer paper (20 lb.?) and yellow glue,
slightly diluted with water. Do both sides at once to avoid warping. Paint
the glue on thinly, apply the paper, then press under a heavy book between
waxed paper. In a few hours the glue will have set, and you can swap the
waxed paper for a few layers of paper towels so they dry faster. Leave them
under the books for at least a day.
I just did a set of fins the other day with a new technique that
Rick Polzllo turned me on to: 3M Super 77 spray adhesive. Just spray the
balsa and the paper, let it tack up a few minutes, then stick them together.
It worked out well. I think the yellow glue gives you a stiffer fin (the
Super 77 stays elastic when it's "dry") but this is really fast.....well
under an hour vs. a day or two.
With either technique you should seal the edges after you round them
off. I've used sanding sealer or CA glue.
Good fillets areas important as lamination for strong fins. I think
5 min. epoxy is the way to go. masking tape to define the edges, run a bead
of epoxy along the root and shape it with the tip of a popsicle stick. then
peel off the tape. Fast, strong, and attractive.
--
Jim Z in Vermont
JimZ...@adelphia.NoThanks.net
(to reply by e-mail, remove the polite decline from my address)
Rick Polzello
I use Southworth 28 lb inkjet paper. (please note the brand and type is not
important.) I think the heavy bond adds strength.
I bond it to the balsa with 3M Super 77 spray adhesive. Spray the balsa and
paper. Let dry about a minute and then stick them together.
After the fins are mounted to the rocket seal the non-root edges with CA.
This method is extremely fast and remarkably strong.
I haven't worked with Basswood much so I can't comment on a strength
comparison.
Burt Holyfield <bu...@midsouth.rr.com> wrote in message
news:AZHR5.13930$7P6.1...@typhoon.midsouth.rr.com...
Bill Morgan
My method is much like the others already mentioned. I start with good
quality ink jet printer paper. I bond the paper to the fin using a glue
stick (UHU, or Ross). I liberally smear the glue onto a traced outline
of the fin on the paper, and then press the fin onto the paper. There
may be some wrinkling or puckering, but it will dry taut. Trim off the
excess and repeat the process on the other side. Seal the edges of the
balsa, and the edges of the paper to the balsa with some CA. I usually
run the CA about a 1/4" around the edge of the fin. I don't use the CA
on the root edge, so that I can get a good bond when its time to glue
the fin to the body tube. You will find that by sealing the edges in
this manner, you will have no trouble shaping the edges of the fins, and
the paper will stay put. Give the final product a couple of coats of a
sanding sealer and sand smooth with some fine-grained sand paper. You
will end up with a very durable and very smooth fin.
Bill Morgan, CAR S274 (Level 1)
Treasurer,
Canadian Association of Rocketry
Calgary Rocketry Association
Andy Waddell
label paper (the stuff that's for mailing labels). You can get it in larger
sizes than mailing labels. It self adheres to the fin, and a little CA on
the trailing edge after cutting it off with an XActo works great.
Strengthens nicely and quickly, and gives a good paint surface. I have
10-year-old rockets using this technique and they still look great. One
caveat: the 8.5x11 size uses a less aggressive adhesive, so use a little
artist's spray adhesive on it first. All the other sizes work fine as is.
--
Andrew D. Waddell
PML Online Support Rep
TRA 2043 L2/NAR 52875 L2
Email: ADWa...@home.com
PML: www.publicmissiles.com
"Bill Morgan" <bill-...@home.com> wrote in message
news:3A17F731...@home.com...
Peter Clay
I have some scrap fiberglass sheet I plan to use for fins on a 4" diameter
rocket. I'd like the finished fins to be thickly airfoiled for appearance.
I'm thinking of using a film of epoxy or CA to bond 1/8" balsa to both sides of
the sheet and then carving/sanding the balsa to the desired shape. I've also
considered using plywood instead of balsa on the TTM tab and first inch or so
along the root edge, and balsa on the remaining 4" to the tip for easier
carving. The finished fins will be retro/scifi/art deco in layout, about 5"
span, 7" root edge.
Thoughts? Experiences?
Peter W. Clay NAR 18619 SR L1 OREO 555
If it dies, it's biology; if it blows up, it's chemistry; if it breaks, it's
physics.
Jim Z in VT
Andy Waddell wrote:
> use Avery
> label paper (the stuff that's for mailing labels). You can get it in
larger
> sizes than mailing labels. It self adheres to the fin, and a little CA on
> the trailing edge after cutting it off with an XActo works great.
> Strengthens nicely and quickly, and gives a good paint surface.
Wow, now we're getting somewhere......First we cut the time frame
from a day to an hour by going from yellow glue to spray adhesive. Now we've
eliminated the need to mess with glue at all with this self-adhesive label
paper. I like where this is going!
( how about eliminating the paper entirely? it won't be strong, but
man will it be quick!!! ;-)
Jim Z in VT
Peter Clay wrote:
> OK, I'm gonna hijack this instructive thread for a related question.
>
> I have some scrap fiberglass sheet I plan to use for fins on a 4" diameter
> rocket. I'd like the finished fins to be thickly airfoiled for
appearance.
> I'm thinking of using a film of epoxy or CA to bond 1/8" balsa to both
sides of
> the sheet and then carving/sanding the balsa to the desired shape. I've
also
No personal experience Peter, but I don't see why this wouldn't
work. I'd sand the 'glass well for good adhesion. Seems like balsa would be
a heck of a lot easier to shape to a thick airfoil than ply would (get it?
ply-would? plywood? pretty good one, eh?? :-) Why not stop the balsa at
the airframe and just extend the 'glass for the fin tabs? Is it too thin on
it's own?
Bob Kaplow
> Wow, now we're getting somewhere......First we cut the time frame
> from a day to an hour by going from yellow glue to spray adhesive. Now we've
> eliminated the need to mess with glue at all with this self-adhesive label
> paper. I like where this is going!
I don't know how this self adhesive paper compares wit the stuff that was
aroud years ago, but the stuf that came with the original Gyroc kits would
delaminate after a few years.
> ( how about eliminating the paper entirely? it won't be strong, but
> man will it be quick!!! ;-)
There are other materials besides paper to reinforce balsa with. I use dope
and tissue on most all of my BGs, but silkspan and Monokote (or Econokote)
also come to mind. I did Silkspan on one of the cone balsa egglofters, but
it was heavier than the jap tissue. I've used Econokote on fins for Fat Boy,
Big Daddy, Big Dawg, Big Bertha, and a handful of other balsa finned models.
Bob Kaplow NAR # 18L TRA # "Ctrl-Alt-Del"
Kaplow Klips & Baffle: http://www.nira.chicago.il.us/Leading_Edge/MayJun00.pdf
NIRA: http://www.nira.chicago.il.us NAR: http://www.nar.org
hern...@fill.zzn.com an...@eircom.net postm...@127.0.0.1 FTNC...@aol.com
lisa...@ntlworld.com to...@cartoonbank.com joel....@welshexec.com u...@ftc.gov
homewo...@alloymail.com Lisa.C...@attunity.com k...@net2000.com.au
David...@trendmicro.com web...@trendmicro.org Newsl...@editor.com
Ed Begle
<jimz...@adelphia.NoThanks.net> wrote:
<snip>
>
> No personal experience Peter, but I don't see why this wouldn't
>work. I'd sand the 'glass well for good adhesion. Seems like balsa would be
>a heck of a lot easier to shape to a thick airfoil than ply would (get it?
>ply-would? plywood? pretty good one, eh?? :-)
You will be punished for that
- Ed
Remove ".swg" to reply
AkaZilla
>>end snip
I use carbon fiber and epoxy to reinforce/laminate balsa. Overkill, I know, but
very effective and strong.
Larry
Dusty Rhoades
AkaZilla <akaz...@aol.com> wrote in message
news:20001120135522...@ng-fl1.aol.com...
> begin snip<<There are other materials besides paper to reinforce balsa
with.
> >>end snip
I get excellent results using SilkSpan and Krylon spray paint. The method I
use is very similar to that used to lay up fiberglass with resin.
--
Dusty Rhoades
IAR #132 *Founding Member*
bo...@pinn.net
Gene Costanza
shoplifting.
Dare I say there's no way to amputate a MOUTH!!!
Well, it was typed so build about a hundred more of those BEYOOOOTIFUL
rockets you build and we will come for your fingers later.
Don't quit your day job, Jimmy Boy...
:-)>
Who luvs ya, baby?
Jim Z in VT
> Jim, you could have a hand grossly amputated in some .....
> Dare I say there's no way to amputate a MOUTH!!!
>
> Well, it was typed so build about a hundred more of those BEYOOOOTIFUL
> rockets you build and we will come for your fingers later.
The hand surgeon took care of one of them yesterday, temporarily.
Minor surgery to remove a deep cyst. So I've got a few days off to eat
codeine and kill time in front of the computer. I'll TRY to refrain from any
more lame puns....no guarantees though ;-)
Ed Begle
wrote:
>Jim, you could have a hand grossly amputated in some countries for
>shoplifting.
>
>Dare I say there's no way to amputate a MOUTH!!!
>
>Well, it was typed so build about a hundred more of those BEYOOOOTIFUL
>rockets you build and we will come for your fingers later.
>
>Don't quit your day job, Jimmy Boy...
>
>
>:-)>
>
>
>Who luvs ya, baby?
>
>
Joey, ... hey Joey! wake up ... call Sammy no-neck and Johnny
meatloaf, we got a job up in Vermont.
Gene: It's a first offense, how about we do a number 3 instead? You
know:
Shave his head
Paint him red
Roll him in the dirt
And throw him in bed
Worked for Hoffa, whatda think?
Remove ".swg" to reply
M
of us have long suspected. Many have also given rise to "creative moments"
i.e. Kaplow Klips, etc
. <snip> I use dope...........and tissue on most all of my BGs, but silkspan
and Monokote (or Econokote)
"Burt Holyfield" <bu...@midsouth.rr.com> wrote in message
news:AZHR5.13930$7P6.1...@typhoon.midsouth.rr.com...
John H. Cato, Jr.
Peter Clay wrote
>OK, I'm gonna hijack this instructive thread for a related question.
>
>I have some scrap fiberglass sheet I plan to use for fins on a 4" diameter
>rocket. I'd like the finished fins to be thickly airfoiled for appearance.
>I'm thinking of using a film of epoxy or CA to bond 1/8" balsa to both sides
of
>the sheet and then carving/sanding the balsa to the desired shape. I've
also
>considered using plywood instead of balsa on the TTM tab and first inch or
so
>along the root edge, and balsa on the remaining 4" to the tip for easier
>carving. The finished fins will be retro/scifi/art deco in layout, about 5"
>span, 7" root edge.
>
>Thoughts? Experiences?
Peter, I understand where you're coming from on this approach, but a few
points to consider...
A fin is like a wide, flat steel I-beam in application. You will remember
that the classic I-beam has the (much thicker and heavier) horizontal
'flanges' on the top and bottom and a (relatively thinner) )(vertical) 'web'
that connects the flanges. The reason for this layout is that the major
stresses in a beam are where the flanges are -- this is why all the material
is there - with only enough 'web' material to keep the flanges apart. And
distance is key here -- as a deeper beam, or a thicker fin (i.e. flanges
farther apart) is a stiffer beam - given the same amount of material - and,
thereby, more efficient.
Now, if we take that same thinking an apply it to fins, we arrive at the
conclusion that the *skins* of a fin is where the strength should be (i.e.
the 'flanges' of this new, wide, flat 'beam') and the part that keeps those
two skins separate now serving the purpose of the 'web'. IOW, putting the
strongest material (the G-10) in the *middle* of this sandwich is just where
you *don't* want to put it (for maximum effiiciency and strength). The best
approach (strengthwise) would be to put the balsa in the middle and the G-10
on the outside (this is, in effect, the situation of foam fins covered with
carbon (etc) -- and how amazingly strong they are). The real important thing
in these built up constructions is that *none* of the components move or
shift relative to one another - or else the strength is lost. That
'anchorage' must be continuous and unyielding. If spread out over the entire
contact surface, the inidividual unit shearing stresses are low enough that
even something like foam can serve nicely (of course, as anyone who's worked
with urethane foam will attest, there's plenty enough 'stickiness' to do
<G>).
So, instead of "balsa - f/g - balsa", a much better approach would be "f/g -
balsa - f/g", as it puts the strongest material in the place where it is
needed the most.
I understand that practical considerations can override - and if you're
trying to build up some thickness "for appearance sake" - as in scale models
or 'concept models', all this may not matter (especially if you don't need
the strength) - and that is fine. If one is using the approach for
strength's sake, the better approach is to 'reverse' one's thinking, however.
I would, however, in your 'balsa skins' approach put a thin layer of f/g
cloth over the leading edge, back an inch or so on both sides, to make sure
you don't have any 'aerodynamic delamination' in flight.
-- john.
Bob Kaplow
> So, instead of "balsa - f/g - balsa", a much better approach would be "f/g -
> balsa - f/g", as it puts the strongest material in the place where it is
> needed the most.
John is absolutely correct. If you want stong light fins, make them of
balsa, and glass the balsa. The balsa need only be strong enough to keep the
layers of glass seperated, and ideally would be end grain balsa, something
I've never seen in modelling thicknesses. If anyone does have a source for
end grain sheets, please let me know.
Andy Schecter
> balsa - f/g", as it puts the strongest material in the place where it is
> needed the most.
John:
I've had quite a bit of experience laminating balsa or styrofoam over a G-10
core. I agree with you that maximum strength and efficiency will result from
laminating thin G-10 over foam. But there are many practical reasons to do the
reverse:
1. You can't laminate G-10 or plywood over a core with a compound curve
2. The G-10 core with balsa or foam laminated on either side makes a perfect
sanding guide to keep the airfoil symmetrical
3. The G-10 core is great for mounting the fin perfectly parallel to the
centerline of the airframe.
4. If you cover the balsa-f/g-balsa assembly with fiberglass cloth (which is
what I've always done) you end up with a fin that can be extremely strong and
stiff.
5. You can drill large lightening holes in the G-10 core to significantly
lighten the whole assembly without losing much strength.
-Andy
Peter Clay
>The best approach (strengthwise) would be to put the balsa in the middle and
the G-10 on the outside
> "Andy Schecter" sche...@rochester.rr.com added
>I agree with you that maximum strength and efficiency will result from
laminating thin G-10 over foam. But there are many practical reasons to do the
reverse:
[Peter replies:]
In this case the .10" G-10 scrap I have is more than strong enough without the
balsa. I'm looking for shape and also tend to think the balsa thickness will
damp vibrations and flutter. I do agree with John from a strict engineering
standpoint, but I also think the G-10 core will be the strongest thing to put
through the body tube. I'm hearing that it might be a good idea to put a f/g
skin on the whole thing after it's shaped, and that's completely practical.
The rest of the rocket is going to have a couple plies of 2oz. glass on it,
anyway, as I see it now.
Thank you for your input. The voice of experience -- which each of you have --
is just what I was looking for.
Bob Kaplow
> I've had quite a bit of experience laminating balsa or styrofoam over a G-10
> core. I agree with you that maximum strength and efficiency will result from
> laminating thin G-10 over foam. But there are many practical reasons to do the
> reverse:
> 1. You can't laminate G-10 or plywood over a core with a compound curve
You don't use G10. you use the same fiberglass cloth you've been wrapping
over tubes and other components, the same epoxy resin, and the same
procedures.
> 2. The G-10 core with balsa or foam laminated on either side makes a perfect
> sanding guide to keep the airfoil symmetrical
> 3. The G-10 core is great for mounting the fin perfectly parallel to the
> centerline of the airframe.
> 4. If you cover the balsa-f/g-balsa assembly with fiberglass cloth (which is
> what I've always done) you end up with a fin that can be extremely strong and
> stiff.
> 5. You can drill large lightening holes in the G-10 core to significantly
> lighten the whole assembly without losing much strength.
Regardign the last two, you can now drill out a lightening hole in the G10
that is the size of the fin! i.e. just leave it out completely.
AkaZilla
I have some 1/4 inch thik end grain Balsa core. How much are you needing?
Larry
John H. Cato, Jr.
Andy Schecter wrote:
>I've had quite a bit of experience laminating balsa or styrofoam over a G-10
>core. I agree with you that maximum strength and efficiency will result
from
>laminating thin G-10 over foam. But there are many practical reasons to do
the
>reverse:
I agree with each and every one of your 'practical deviations', Andy - and,
in fact, used just about every one of them on my Nike fins (modified
double-wedge) <g>. Only exception (maybe) was that that I 'skinned' the
whole shooting match with 0.030" G-10 as that 'outer skin' (could do this,
since the finished surfaces were planar -- well, nearly). Dang strong, too.
I understand, also, Peter's situation of the fact that he really didn't
*need* any additional strength beyond a 'base G-10', and that's OK, too
(which is why I added that 'understanding' comment at the end). I just used
his post as a 'hook' to talk structures a little <g>.
Best thing (that I think would bear repeating) is -- if you're going this far
(and need at least a base G-10 core), a layer or two of f/g cloth over the
whole thing would probably triple the strength (maybe even more) of just a
G-10 core with some balsa overlay. Admittedly, a little more work - but not
a lot for what you get for the effort.
--- john.
[good list of reasons to put the balsa OVER the G-10]
John H. Cato, Jr.
Ned Nassif
> >I have some 1/4 inch thik end grain Balsa core. How much are you needing?
"John H. Cato, Jr." <jc...@accessatc.net> wrote in message
news:8vmki9$52ep0$1...@ID-30789.news.dfncis.de...
> I'm intersted, too.
>
> -- john.
Not sure how much Larry has to spare, but..
Was originally reply to Bob's post but thought that 1/4" wouldn't fit his
specs. Here's a place that has some goodies with decent pricing.
http://www.fiberglasssupply.com/Product_Catalog/Core_Materials/core_material
s.html
Ned Nassif
--
Remove spamfood from sig to reply via email
Andy Schecter
> > I agree with you that maximum strength and efficiency will result from
> > laminating thin G-10 over foam. But there are many practical reasons to do
the
> > reverse:
> > 1. You can't laminate G-10 or plywood over a core with a compound curve
> > 2. The G-10 core with balsa or foam laminated on either side makes a perfect
> > sanding guide to keep the airfoil symmetrical
> > 3. The G-10 core is great for mounting the fin perfectly parallel to the
> > centerline of the airframe.
> > 4. If you cover the balsa-f/g-balsa assembly with fiberglass cloth (which is
> > what I've always done) you end up with a fin that can be extremely strong
and
> > stiff.
> > 5. You can drill large lightening holes in the G-10 core to significantly
> > lighten the whole assembly without losing much strength.
Bob Kaplow replied:
> Regardign the last two, you can now drill out a lightening hole in the G10
> that is the size of the fin! i.e. just leave it out completely.
[Andy replies:]
Bob, this comes down to an 'engineering' decision, a choice of construction
methods, and is, in the end, simply a matter of taste. I like a G-10 or plywood
core for reasons '2' and '3' above. There's another advantage, too: the core
adds great strength with little weight penalty if you run it through the wall to
the motor tube.
You may not agree with this approach. Obviously, folks out there may try it both
ways and see what they like.
--
-Andy
Peter Clay
>I understand, also, Peter's situation of the fact that he really didn't *need*
any additional strength beyond a 'base G-10', and that's OK, too (which is why
I added that 'understanding' comment at the end). I just used his post as a
'hook' to talk structures a little <g>.>
Well, John, I appreciate you "talking structures a little." And currently I
intend to give it a glass cloth skin, as you suggested, and drill a lot of
holes in the core as Andy suggested. I still want the core to serve as the TTM
tab and another rocket has shown me the value of a solid piece of G10 at the
trailing corner to land on. :-)
Bob Kaplow
>>I have some 1/4 inch thik end grain Balsa core. How much are you needing?
Careful John, folks are now going to think that 1/4" end grain balsa
laminates are the key to the overthrow of TRA.
:-)
[well, I TRIED to throw them off the track, now back to the TRA ending balsa
project in the basement]
AkaZilla
The 1/4 inch thick stuff came from BALTEK. They sell it in sheets. This stuff I
got was originally in sheets that were 2 foot by 4 foot IIRC. Most of what I
have is small ends and trim off's from an aircraft project.
I could not tell you how much the material cost. I was not purchasing agent,
and we bought the stuff by the case. I think they do have more than the one
thickness.
Larry
Leonard Fehskens
wrote
>IOW, putting the
>strongest material (the G-10) in the *middle* of this sandwich is just where
>you *don't* want to put it (for maximum effiiciency and strength). The best
>approach (strengthwise) would be to put the balsa in the middle and the G-10
>on the outside (this is, in effect, the situation of foam fins covered with
>carbon (etc) -- and how amazingly strong they are).
There *is* a reason to do this - when you're sculpting fins with a thick
airfoil and fairings. The fins on my Starship Vincia (D/E powered) are
5/8" thick at the root and 1/4" thick at the tip, and are fully airfoiled.
They were made from a balsa/plywood/balsa laminate. If I were doing this
for a bigger model, I would do the same thing and then glass the outside
after the fins had been sculpted. Balsa (or foam) is a lot easier to shape
than stronger materials.
len.
Jim Z in VT
Gene Costanza wrote:
>
> >Jim, you could have a hand grossly amputated in some countries for
> >shoplifting.
> >
> >Dare I say there's no way to amputate a MOUTH!!!
> >
> >Well, it was typed so build about a hundred more of those BEYOOOOTIFUL
> >rockets you build and we will come for your fingers later.
> Joey, ... hey Joey! wake up ... call Sammy no-neck and Johnny
> meatloaf, we got a job up in Vermont.
>
> Gene: It's a first offense, how about we do a number 3 instead? You
> know:
>
> Shave his head
> Paint him red
> Roll him in the dirt
> And throw him in bed
Sounds like an interesting way to finish a rocket!
--
Jim "watching his back" Z in Vermont
Robert Briody
Burt Holyfield wrote:
>
> I have read a couple of post talking about laminating balsa fins with
> paper and would like some more info please.
>
> #1. What type of paper do you use?
>
> #2. What type of glue (white, CA, of epoxy)?
>
> #3. How does this compare to replacing the balsa with basswood?
>
> I've got a dozen Estes rockets with broken fins, from not to soft but not
> hard landings, to be replaced and I am wanting to try something to stop
> this. Some of the fins are broken at the body tube and others are in the
> middle of the fin.
>
> Any and all recommendations are greatly appreciated.
>
> Burt Holyfield
--
Hi Burt,
I have a two word solution to your problem ... Kevlar Veil.
I laminated the fins on my Estes Big Daddy with Kevlar Veil. The internal epoxy
fillets to attach the fins to the motor tube are kevlar filled epoxy This is one
tough rocket! After a few flights, I can hardly tell it's been flown! I
purchased my Kevlar Veil from Shadow Composites (http://www.shadowaero.com/). I
don't have any interest in Shadow Composites ... they sell a quality product at
a fair price and have excellent service.
Regards,
Robert Briody
TRA #4945 L2
Bob Kaplow
> I have a two word solution to your problem ... Kevlar Veil.
>
> I laminated the fins on my Estes Big Daddy with Kevlar Veil. The internal epoxy
> fillets to attach the fins to the motor tube are kevlar filled epoxy This is one
> tough rocket! After a few flights, I can hardly tell it's been flown! I
> purchased my Kevlar Veil from Shadow Composites (http://www.shadowaero.com/). I
> don't have any interest in Shadow Composites ... they sell a quality product at
> a fair price and have excellent service.
Is this the same stuff I've seen called Kevlar Matte? It kind of looks like
scaled up Jap tissue. If so, it's great for lots of things, but "fuzzes"
real bad. If you're laminating inside a sandwich, it's not a problem, but
for fin exterior finish, I'd say vacuum bagging or sandwiching between glass
plates is a must.
Mark Simpson
Andy Schecter wrote:
John:
> I've had quite a bit of experience laminating balsa or styrofoam over a G-10
> core. I agree with you that maximum strength and efficiency will result from
> laminating thin G-10 over foam. But there are many practical reasons to do the
> reverse:
> 1. You can't laminate G-10 or plywood over a core with a compound curve
> 2. The G-10 core with balsa or foam laminated on either side makes a perfect
> sanding guide to keep the airfoil symmetrical
> 3. The G-10 core is great for mounting the fin perfectly parallel to the
> centerline of the airframe.
> 4. If you cover the balsa-f/g-balsa assembly with fiberglass cloth (which is
> what I've always done) you end up with a fin that can be extremely strong and
> stiff.
> 5. You can drill large lightening holes in the G-10 core to significantly
> lighten the whole assembly without losing much strength.
>
> -Andy
Andy,
Have you ever tried using flexible fiberglass sheeting like that used for molding?
It's available in a variety of thicknesses and is flexible enough to be rolled up
into a 6" diameter cylinder or thereabouts. I have a couple of sheets from a
company in Canada that has pallets of the stuff sitting outside as scrap. I
haven't gotten around to trying any yet, so I can't tell you how well it works.
Mark Simpson
NAR 71503 Level II
Andy Schecter
> Have you ever tried using flexible fiberglass sheeting like that used for
molding?
> It's available in a variety of thicknesses and is flexible enough to be rolled
up
> into a 6" diameter cylinder or thereabouts. I have a couple of sheets from a
> company in Canada that has pallets of the stuff sitting outside as scrap. I
> haven't gotten around to trying any yet, so I can't tell you how well it
works.
Markie Mark:
I've used G-10 sheet for rolling a bunch of shrouds and nosecones. 0.010" is
easiest to roll (down to around 1.5" diameter), but is pretty flimsy, and
requires a reinforcement of fiberglass cloth over it for all but the smallest
rolled shapes. 0.020" makes a nice strong shroud that is pretty strong even
without further reinforcement. But it's a bitch to roll in the smaller diameters
(like maybe 5" or less). Lately I've found that 0.015" G-10 is a good compromise
between strength and rollability.
For rolling larger diameter stuff (maybe 6" dia and up) I like using 1/32" birch
plywood. It's nice to work with, can still be cut with scissors, and epoxy
penetrates it well.
-Andy
Todd Harrison
Laminate newspaper on both sides with 6oz. glass and you've got great
fins for low power rockets....
Todd Harrison
TRA 8162
Mark Simpson <mark.s...@home.com> wrote in message
news:3A243E68...@home.com...
>
>
> Andy Schecter wrote:
>
> John:
>
> > I've had quite a bit of experience laminating balsa or styrofoam over a
G-10
> > core. I agree with you that maximum strength and efficiency will result
from
> > laminating thin G-10 over foam. But there are many practical reasons to
do the
> > reverse:
> > 1. You can't laminate G-10 or plywood over a core with a compound curve
> > 2. The G-10 core with balsa or foam laminated on either side makes a
perfect
> > sanding guide to keep the airfoil symmetrical
> > 3. The G-10 core is great for mounting the fin perfectly parallel to the
> > centerline of the airframe.
> > 4. If you cover the balsa-f/g-balsa assembly with fiberglass cloth
(which is
> > what I've always done) you end up with a fin that can be extremely
strong and
> > stiff.
> > 5. You can drill large lightening holes in the G-10 core to
significantly
> > lighten the whole assembly without losing much strength.
> >
> > -Andy
>
> Andy,
> Have you ever tried using flexible fiberglass sheeting like that used for
molding?
> It's available in a variety of thicknesses and is flexible enough to be
rolled up
> into a 6" diameter cylinder or thereabouts. I have a couple of sheets
from a
> company in Canada that has pallets of the stuff sitting outside as scrap.
I
> haven't gotten around to trying any yet, so I can't tell you how well it
works.
>
Bob Kaplow
> Thought I'd share a tip....
>
> Laminate newspaper on both sides with 6oz. glass and you've got great
> fins for low power rockets....
Why even bother with the newspaper?
Todd Harrison
wet it out right there.... Prevents anything from getting on the working
area and don't have to worry about pealing off wax paper or anything like
that..... Basically just a personal preference and could be done without the
newspaper.
-Todd
Bob Kaplow <kapl...@eisner.decus.org.mars> wrote in message
news:VzDSkI...@eisner.decus.org...
> In article <ZOYU5.22$R62....@news1.wwck1.ri.home.com>, "Todd Harrison"
<this...@home.com> writes:
> > Thought I'd share a tip....
> >
> > Laminate newspaper on both sides with 6oz. glass and you've got
great
> > fins for low power rockets....
>
Mark Simpson
Mark Simpson
NAR 71503 Level II
Bob Kaplow wrote:
> In article <ZOYU5.22$R62....@news1.wwck1.ri.home.com>, "Todd Harrison" <this...@home.com> writes:
> > Thought I'd share a tip....
> >
> > Laminate newspaper on both sides with 6oz. glass and you've got great
> > fins for low power rockets....
>
Mark Simpson
Thanks for the tips.
Mark Simpson
NAR 71503 Level II
Peter Clay
for glass. We're talking about 1/8" contest balsa laminated to each side of
.10" G-10. The balsa is for visual effect.
As suggested by people on this thread, I drilled 72 (7/16" dia.) holes in the
stack of G10 cores to reduce weight, then epoxied the balsa to both sides and
carved/sanded out the airfoil. Next I will cover both sides with 2 oz.
fiberglass cloth and epoxy. I already peeled the glassine off the motor can
body tube and applied glass to that.
The visual effect so far is not as dramatic as I had envisioned. To get what I
wanted, I would have had to use balsa at least twice as thick. These are nice
fins, though, and they certainly are stiff and strong, even unfinished. One
thing I really like: the glass gives me a consistent center so that the airfoil
stays symmetrical, and the glass tab fits tightly into a slot that is
mechanically parallel to the tube, making alignment easy. I know from
experience that visually lining up an airfoiled fin can be tricky.
Pretty heavy, though. This ain't no model rocket. I'm going to lob it with
H238-6, but it really won't be happy until it gets its J350, which is probably
a year away.