Building Tips and technical articles. => Building techniques => Topic started by: jose modesto on May 12, 2013, 10:20:16 PM
Title: molded balsa fuse
Post by: jose modesto on May 12, 2013, 10:20:16 PM
Molded fuse for new model. Sina and I worked on a new model with round fuse. The model was developed by Sina from a photo that was posted of a fantasy plane. usually i make a femalemold and vacuum bag the balsa shells. This time i dint have the time for a female mold so i developed a modified Al Rabe construction. Sina last model was a composite shell model called tweener ''2ENR'' Sina used the dimmensiond of this model to develope the new fuse. the fuse shown is the fuse that was developed for me. Sinas version differs and is sleeker than the one shown. this fuse shown is being used in the US version of the Yatsenko Shark as a plug in model. The Fuse completed 5.40z with motor and battery mount. by far this is the strongest fuse to date with more room for E equipment. Sparky do you remember what your T bolts fuse weigh.
jose modesto
Title: Re: molded balsa fuse
Post by: jose modesto on May 12, 2013, 10:21:00 PM
added photos
Title: Re: molded balsa fuse
Post by: jose modesto on May 12, 2013, 10:24:04 PM
added photos
Title: Re: molded balsa fuse
Post by: jose modesto on May 12, 2013, 10:25:19 PM
added photos
Title: Re: molded balsa fuse
Post by: RC Storick on May 12, 2013, 11:26:52 PM
I think around 5 or 6 oz but I don't remember exactly. Good wook Jose.
Title: Re: molded balsa fuse
Post by: Avaiojet on May 13, 2013, 06:25:28 AM
Jose,
Nice work! Kudos!
Way ahead of the pack.
Charles
Title: Re: molded balsa fuse
Post by: jose modesto on May 13, 2013, 07:10:13 AM
SV 22 molded fuse 5.4 oz with e formers and batt mount fuse is 1/32" balsa i was interested in putting CFC on the exterrior the exterior surface molded smooth with out any ridges or high spots
jose
Title: Re: molded balsa fuse
Post by: john e. holliday on May 13, 2013, 08:28:13 AM
Electric sure is changing the style/looks of planes. I like it. y1
Title: Re: molded balsa fuse
Post by: Sina Goudarzi on May 13, 2013, 09:38:27 AM
This was a fun process, When Jose was helping me to trim the Tweener, which took a while, the findings directed us to some construction changes, Forward CG by longer nose, not nose weight was very important. It made the plane very stable with nice corners, Here are some specs of the plane
Tweener Design by Jose Modesto WS: 64.5 equal panels WA: 745 Weight: 64 oz Stab & Elev. Impact, area: 164 Nose @ 11'', Tail @ 19"
Power Package eFlite Power 32 Phoenix 60 FM9 Hubin Timer Sky Lipo 3000 5c 13x5.5 apc e.pusher
Construction Complete composite technology Wing, fuse and stab. Wing has foam insert. no ribs, One hollow tube. There is only two half ribs for LG Carbon fiber re-enforcement for wing tips and nose area (nose from inside)
Others Lines 65 eye to eye Kaz Handle 8.5 cm Lap time 5.3
This is a Big Jim Tweener air foil (High aspect), Impact fuse, stab and Elev.
Title: Re: molded balsa fuse
Post by: Sina Goudarzi on May 13, 2013, 10:28:28 AM
Round Fuse,
began couple years ago when Jose handed me the Al Rabe article on round fuses, We talked over a year and decided to come up with a new fuse based on those criteria, Then Jose gave me an image of a fantasized H-1 racer, we talked around that design for a while, since the number of Tweener was there, the first sketch was done around a year ago, then incorporated the number in the new design,
This was the fun part, Jose and I spent hours and hours last Fall in this fuse design, construction and get it ready for being built. Draw, print, cut and check, next rounds again and again, till we got to where we are.
There is no flat area on the fuse from nose to tail, it's quite large, interestingly less area around the fuse compare to the Tweener fuse, so fuse is wider, but less wood is required. Air flows nicer inside around battery and ESC.
The first ones are 60 size, but we formed a 35 size for next generation, (B. Lampione wants one of this size). The differences between Jose's and mine are roughly
Spinner tail area (fuse) bottom curve Rudder Jose 2.5 more room 4 horn moderate moderate mine 2 less extreme taller
Images: The fantasized H-1 racer
Fuse side Compare top: Tweener Middle: Jose Bottom: Mine
Fuse top Compare top: Tweener Middle: Jose Bottom: Mine
Title: Re: molded balsa fuse
Post by: Avaiojet on May 13, 2013, 11:47:09 AM
Sina,
Your side view drawing. Is that airfoil outline, shown in the drawing, the exact airfoil outline/shape used on the model?
Nice design, I like it.
Charles
Title: Re: molded balsa fuse
Post by: Randy Powell on May 13, 2013, 12:09:40 PM
Very slick, Jose. I have always been fascinated by the amount of work that goes into something like this. I would have to be willing to build several in order to put in the sort of work you need to build so many molds.
Looks very good.
Title: Re: molded balsa fuse
Post by: jose modesto on May 13, 2013, 12:28:12 PM
Thanks Randy. For our models the wing,fuse,stab molds are existing. The only new mold was for the fuse and this was done as a male plug. Randy your new model is slick. My 2011 NATS model started as a tween rudder model just like your last 2 models but I chickened out and added the vertical fin. Again your design work is slick and new. Randy The stab is impact the wing is a tweener and the fuse of the original is impact. The flaps are foam,cut and sheeted by Bob Hunt elev are either sheeted foam or 3/8" tapered balsa and balsa fin and rudder Howard mentioned that the impact fuse molded in this manner should have a curb and not remain flat. The SV fuse shown has flat sides and they require some additional reinforcement. Working on slightly radius impact fuse mold for new fuse mold. Thanks Sina for filling in the facts Your design work on this model is great Jose
Title: Re: molded balsa fuse
Post by: David_Stack on May 13, 2013, 12:35:44 PM
Good Afternon Jose;
Curious, did you use vacuum to form the molded balsa shells around your male 'plug'? One of the photos shows the plug covered in what appears to be plastic wrap, but there is no sign of an evacuation line leading to a vacuum pump...
Can't imagine how quickly you had to work to lay up carbon veil, then trim the balsa skins to fit the compound curves at the nose and lay those up before the resin kicked off. How did you keep those balsa strips in place prior to pulling vacuum (assuming you did)?
Do you foresee ever being able to get rid of the formers aft of the wing, and allowing the fuselage skins themselves to carry the structural loads?
r/ Dave
Title: Re: molded balsa fuse
Post by: jose modesto on May 13, 2013, 02:09:16 PM
Dave the fuse is constructed in this manner after the male plug is made 1) make balsa sheet out of 2 1/32"x4x48" 2) wet balsa sheet Wrap around male plug with ace bandages. Note the balsa sheet must be cut at front fuse as fuse get narrower similar to wall paper were one sheet overlaps the other and you cut at seam pull double piec out 3)prepare male plug by wrapping with with seran wrap,wax paper. Or finish male plug to high finish polish and wax Note if u use seran wrap wax with pledge or similar 4) begin with glass cloth and epoxy direct to male plug proceed with the rest of the interior lay up 5) place pre molded balsa shell on male plug then apply exterior glass cloth 6) cover with wax paper and place in vacuum bag note the wax paper is to protect the vacuum bag 7) remove and trim edges This the the process for shell production Dave r typically I don't use formers after the leading edge of the wing to the rear post. This model is being built on a set of 3/8" rods as a modified Al Rabe fuse construction If I had the time for female mold the fuse would be built in the mold and not need all the formers shown Typically with female molds a can get away with out ribs for wing construction or formers for fuse. The curb fuse makes this easy and light. Jose
Title: Re: molded balsa fuse
Post by: Randy Powell on May 13, 2013, 02:25:13 PM
Not much different than doing molded top and bottom blocks that you are reinforcing with fiberglass or carbon. I used saran wrap and ace bandages.
Title: Re: molded balsa fuse
Post by: jose modesto on May 13, 2013, 02:45:38 PM
Randy that's why I call it a modified Al Rabe molding system. The difference is in using 3/8" rods for fuse former alignment. I prefer to work with the female molds as alignment is much easier and formers can be installed while in the mold. Jose
Title: Re: molded balsa fuse
Post by: MarcusCordeiro on May 14, 2013, 11:57:20 AM
I like this thread. Amazing work Jose. And my brother works with fiberglass... Really interesting way to make fuselages, I mean, a whole model.
Marcus
Title: Re: molded balsa fuse
Post by: Sina Goudarzi on May 15, 2013, 04:53:43 AM
Your side view drawing. Is that airfoil outline, shown in the drawing, the exact airfoil outline/shape used on the model?
Nice design, I like it.
Charles
Yes it is.
Title: Re: molded balsa fuse
Post by: Doug Moon on May 15, 2013, 07:27:15 AM
Jose and Sina,
This stuff is awesome! Thanks for showing it. I remember reading the Al Rabe article and always wanted to try it.
When you built your male mold did you make it one complete fuse then split it or did you build it in two halves? If you did split it how did you go about it?
Thanks
Title: Re: molded balsa fuse
Post by: jose modesto on May 16, 2013, 06:37:07 AM
Hey Dough. Belated congrats on Nat's Win. The way i count this is #2. Doug,on this fuse i built right and left fuse male plugs. Sina was able to loft accurate formers. this allowed me to build the Bucks just like Al Rabe. one fuse buck was built out of balsa the other was built using blue foam. Typically i build a complete fuse and cast left and right female molds. on this model I dint think i had the time to build female molds so i developed the rod method for building a fuse.Just like a wing built on rods. The mothod i used was to cut out fuse outline from plans,glue plan outline to 3/32" 5 ply NOTE: I vaccum bag the 3/32" ply with epoxy and glass cloth on a perfectly flat surface,this insures that the form stays flat. Second I glue the half formers to base then fill between with(foam,wood) shape and sand to final shape. Since this plug is not for female molds the finish surface is not as critical. additional photos Jose Modesto
Title: Re: molded balsa fuse
Post by: jose modesto on May 16, 2013, 06:39:11 AM
additional photos The last 2 photos show the full SV-22 full fuse and the female molds cast from fuse. if you look closely you can see the center line used for right and left parting point.
Title: Re: molded balsa fuse
Post by: RC Storick on May 16, 2013, 12:42:08 PM
Jose I would like to buy a right and left half. No wing cutout so just raw molded wood and the formers. Shoot me a price please.