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Old Apr 17, 2010, 06:07 AM
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foam ribs?

hey guys......
not sure if this has ever been done before, but while i'm sitting here reading on the net a thought came to me!
i been in this hobby for afews yrs. off and on...(when ya have afew kids it's more off then on).
so anyway....
i'm looking at this purely from a sailplane/glider perspective. if it has a motor it's not for me!
powered flight doesn't capture the imagination for me. however soaring from a thermal....now that does it!
one of the issue's that keeps showing up on post's is the fact that thinner airfoils can somehow be obtained when using foam vs. balsa. i'll be the first to tell ya that i completly don't fully understand this. perhaps some here can better explain this to me?
wouldn't it be feasible to make ribs with foam/carbon or the like? then use whatever covering material that fits the bill?
from my limited knowledge i would assume that this is more then do-able.
i'm i right when i say '' the reason why we use carbon in this hobby isn't for weight reduction but more for it's compression ability''?
what are some\all the cons of 1\4'' foam sandwiched between carbon?
like i said, i'm not sure if this has been done yet.
any thoughts on this?
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Old Apr 17, 2010, 06:41 AM
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“” perhaps some here can better explain this to me?
wouldn't it be feasible to make ribs with foam/carbon or the like? then use whatever covering material that fits the bill? “”dirtybirdy

Some good reading and harmony

http://www.gliders.dk/airfoils.htm

http://www.av8n.com/how/htm/airfoils.html

http://www.ae.illinois.edu/m-selig/a...atabase.html#H

http://www.auf.asn.au/groundschool/u...4.html#washout

Adkins and Clark
http://beemp3.com/download.php?file=...Dueling+Banjos

...
Image, Clark Y covered with food wrap
....

John
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Old Apr 17, 2010, 07:48 AM
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Here's an idea that worked for us .... You can hot wire a wing section out of the thicker Foams (2" ) Cut in spar slots , etc. and then just slice off as many ribs as you need ... We tried foam ribs about 20 years ago , with great results ... we made them a bit thicker than Balsa ribs ... the larger the wing , the thicker the ribs ... No problems and it was a LOT less expensive and time consuming than making balsa ribs... The ribs only serve to keep the covering apart , and the spar(s) is the STRENGTH of the wing ..
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Old Apr 17, 2010, 08:24 AM
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Quote:
Originally Posted by gpw View Post
Here's an idea that worked for us .... You can hot wire a wing section out of the thicker Foams (2" ) Cut in spar slots , etc. and then just slice off as many ribs as you need ... We tried foam ribs about 20 years ago , with great results ... we made them a bit thicker than Balsa ribs ... the larger the wing , the thicker the ribs ... No problems and it was a LOT less expensive and time consuming than making balsa ribs... The ribs only serve to keep the covering apart , and the spar(s) is the STRENGTH of the wing ..

This sure does sound very interesting idea, now what types of wings can be built this way and can you sheet them with balsa or depron sheeting?

Can this method be used for large delta wing airplanes, say 6' wingspan models....What are other complications to be considered if the wing is for EDF jet and would have landing gears mounted and nacelles with EDFs hung on the underside of the wing....any thoughts??, anyone...


Sam
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Old Apr 17, 2010, 08:51 AM
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You can build most any wing you want like this ... we covered them in everything from Monokote (Econocote), Micafilm , Balsa, even thin cardboard ... All worked fine ...
Hang your landing gear attachments on the spars , the strong part . You might want to do some "reinforcing " in the area..
The bigger the wing the better .. weight becomes a lesser consideration.
For Deltas , you can use the pivot method of cutting Delta wings ... Hot wire fixed to a single point on one end , rib template on the other ... cuts a great delta , any sweep you want too , depending where you fix the pivot in relation to the rib template ... Mark your rib positions , and slice away ... (tapered ribs , the EASY way )
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Old Apr 17, 2010, 08:56 AM
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interesting indeed!
my concerns are with DLG planes. so what i'm getting is this.... providing overall wing structure is ridged enough, ect. why are products still being built as they are today?
i'm not so sure about powered flight, but sailplanes spend alot of time at high altitude, and lot of folks mention that they like the sun gleaming through the wing.
or perhaps balsa sheeting, combined with less ribs( or maybe not).
in either case..
something like fan fold or the like, could be cost effective....right? could you imagine how many ribs, ect. could be cut at the sametime? whats the delay on the market for this?
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Old Apr 17, 2010, 08:58 AM
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I built a DR1 a long time ago by hotwiring out a foam core. Sheeted from the leading edge back to where a spar would be. Glued down cap strips about 1/2 in. wide, back to the trailing edge and made a 1 in. wide trailing edge strip. Then poked a hotwire down through the foam between the capped ribs and with a pair of vicegrips on the wire and the power hooked to it, cut out the squares between the ribs. Covered with silkspan and dope tells you how long ago this was. Flew for many years. Made for a very tough, light wing. Best of both worlds.

Gord.
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Old Apr 17, 2010, 09:57 AM
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The "market" is structured to sell you very Expensive toys with a short lifespan ... Unfortunately , it's ALL about the money , not how good they can make something ...
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Old Apr 17, 2010, 10:47 AM
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Quote:
Originally Posted by gpw View Post
You can build most any wing you want like this ... we covered them in everything from Monokote (Econocote), Micafilm , Balsa, even thin cardboard ... All worked fine ...
Hang your landing gear attachments on the spars , the strong part . You might want to do some "reinforcing " in the area..
The bigger the wing the better .. weight becomes a lesser consideration.
For Deltas , you can use the pivot method of cutting Delta wings ... Hot wire fixed to a single point on one end , rib template on the other ... cuts a great delta , any sweep you want too , depending where you fix the pivot in relation to the rib template ... Mark your rib positions , and slice away ... (tapered ribs , the EASY way )

Hello Gpw,

Here is why i asked if this method could be used on big delta wing aircraft.

http://www.rcgroups.com/forums/showthread.php?t=1205746



Sam
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Old Apr 17, 2010, 10:51 AM
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60" span OSG with kfm2 wing from dollar tree foam, haven't painted it yet, but on a clear sunny day, the white wing with sun shining through it is incredibly bright, easily visible at 1200ft. On a grey, hazy day, however, it's invisible. With the right density foam, and airfoil, I'm not sure you need ribs, unless minimum weight is an absolute requirement. full foam wing LE/TE dowels and or single spar with minimum tape (LE, plus maybe a single spanwise strip) versus a spar, ribs, structural LE & TE and covering.
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Old Apr 17, 2010, 12:16 PM
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The Old Easy Riser Ultra Light Hang glider used spruce capped FOAM RIBS !

Going the other way

I have used Balsa ribs and spars and covered them with Blue FFF .
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Old Apr 17, 2010, 12:58 PM
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Bigger the better , eh Birdo
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Old Feb 17, 2016, 01:38 PM
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foam/ carbon ribs

Dirty birdy
i'm starting to build a goat 4 ultralight single seat glider and am considering making foam/ carbon ribs and saw your post
I understand that aircraft foam is needed or it will degrade and lose strength
what have you learned so far
Steve neve
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Old Feb 17, 2016, 03:41 PM
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I used to own an Easy Riser, and EARLY one.
It had foam ribs which were capped with spruce and the LE and TE were then
capped on the sides with Ply which was also Stapled to the Spruce.
The LE and TE ends of each rib were Cupped to fit their respective size LE and TE tubing.

Foam was different back then as the ECO folks have gotten the OC , Dow, Paktiv folks
to change their foaming formulations.

Easy Riser eventually went to Formed Aluminum ribs on their next version.

Read that any way you want !

Hey early Hang gliders were Bamboo and Visqueen, taped together.
It's YOUR butt in the sling so build with that ever makes you the most secure feeling.

I can cut large parts on my CNC as it's a Full 4'x8' steel bed.
Or y0ou can cut whatever you want with a Hot Wire and slice as many ribs form each as you need.

I'm thinking that it's the Vibration that will eventually kill foam parts.

Electric models can get away with Foam because they use SMOOTH running Electric motors.
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