sysiek

My Feedback: (176)

Yes just like Byron F-15 very strong ,the Byron f-15 is about 110" long and the strongest servos at the time haved maybe 145oz.

jofunk

Hi ST I know. You can talk about someones mother easier than you can talk about someones airplane on RCU…………….. Sebastian and Vladimir pointed out that the surface will not be driven by the tube. It will be driven by the servo mounted between 18 and 19 about 10" in front of the tube. The tube will not be rotating the stab. The stab will be rotating the tube. I questioned Vladimirs dowel rods as to the lack of material around the threaded insert. I put them in the picture because he made them. I came up with a wood block to accept the insert sandwiched between hard balsa. It will get set into the stab and then ground to shape above the servo location. Vladimir said digital servos. I don't like digital standard size servos for this application. I am going with a Futaba 3306 MG. It puts out 333 in/oz and the larger size spreads out the mounting hardware. The rudder will get something similar but it may not need to be removed for transport.

sierratango

Got it. Makes much better sense now.

Just a question about something I noticed in one of my past models.

when there is a constant load placed on a servo even in its zero position, the motor seems to run and wiggle and use up battery power. Is that something you have noticed and is that a potential issue here?

It it has been so long since I flew, I can't remember which plane I had that issue on.

thinking about it, as long as the stab is balanced there will not be a load on the servo when on the ground, but there will be a lot of load on the servo in the initial phase of angle of attack chance in flight.

I don't mention it from worry standpoint, simply trying to understand why servos do this, and I don't like it. I also don't like how long servo wire runs mess with things. In my gliders with there long wingspans I have servos that are several feet away from the receiver.

rhklenke

My Feedback: (24)

I would use the carbon fiber pushrods with the metal 4/40 inserts that you JB weld in for that application...

http://www.espritmodel.com/pushrod-a...500-x-5mm.aspx

Bob

jofunk

Hey ST I don't know alot about servos but I think digital servos use a fair amount of power when they are not under load…………Hey bob I don't know if there will be much room for a carbon rod. The linkage points will be about 3" apart the links are about 1" each and the rest will be connecting rod……. The rudder is just under 1" at the root where the 1" tube exits so there was no backfill wood left after sanding flush. I backfilled the area around the tube with some bond. I also cheated and built the area up a little to hide the tube

jofunk

The nose got some 2.7 oz glass laid on it. I wanted to make the nose as stiff as possible before I cut it off the table to flip it over and finish the bottom. A nice cutting mat makes for easy glass cloth cutting with no fraying ends. Although it does create a lot of static, so make sure all the dust and foam bits are off the table. I made a mini mini roller to apply the West Systems resin. It is just a foam mini roller cut into 1" lengths on a Bent up 1/4-20 bolt for a handle. It makes vertical application go pretty quick. The end of the cloth dosen't fray as easily as opposed to spreading the resin with a card spreader. I cut all the tops of the bulkheads for the middle section. They will get glued on and then the contour of all the humps will be traced on and cut out. It looks like I will be a little short on lite ply after I make the fuel tank floor and sides. Thats a 4'x8' sheet of lite ply with as little waste as possible so far.

sierratango

Jofunk,

Looking fabulous. You are really moving along well. Your project looks too good for there only to be one?

Another material I use for cutting fabric is hard board from Home Depot. I scored a few 4' X 8' smooth double sided pieces this weekend. It is the smooth dark particle board, but is has a bad smell to it and irratates my lungs so it is sitting in my storage container for a while. It is probably made in China and is toxic. The roller cutter works fine on this board and the blade hold up fine too. I am using 1.4 oz glass against the mold surface before the carbon fabric goes down.

My first fuselage is composed of different orientations and mixes of. 1.9, 5.6.carbon fabric, 1.5 unidirectional carbon and a 1 mm aramid honeycomb sandwiched between the inner and outer skins.

The use of the honeycomb complicates matters because it requires the use of a vacuum to get the honeycomb to conform to the first skin and then on a seperate instance, to get the inner skin to join against the honeycomb and the edges of the first skin. Two to three steps. The amount of stiffness this honeycomb imparts on the structure is incredible and it makes it light, but there is a learning curve and a lot more work than just doing a solid carbon skin.

The first skins which are against the mold can be laminated up directly into the mold layer by layer, but in some instances laminating the layers of fabric on a flat table top with a squeegee is better. I like to tape the edges of all my fabric patterns except the light fiberglass with blue painters tape and then cut the tape in the middle of the width with the roller blade. The tape helps to hold the orientation of the individual carbon filaments. When I do the layups on the table I do it onto a 3-6 mil plastic sheet and then once the layup is complete, cut on the outside of the tape line and carry the layup with the plastic backing sheet attached. This allows me to position the laminate into the mold and then peel off the plastic backing, leaving the layup to be manipulated into the mold details.

In any case perhaps some of these ideas are useful to you now or in the future. I don't have my own thread, so I'll post this here. You guys seem to appreciate it, and are absolutely serious and I have no where else but my own gallery to post photos.

I never can an figure out how to re orient the photos, sorry.

F86_SABRE

Hi Jo,
Doesn't honeycomb create bubbles during layup? Do you think that with vacuum it would help to extract the air between the honeycomb and push down the fiberglass in the honeycomb structure? I am not quite versed with honeycomb as I use 1/16 (1.5mm) and 3/32 (2mm) airex foam instead in order to avoid the stated issues.
Reuben

jofunk

hey Ruben, that is a question for ST. I've only worked with fiberglass……. Looks good ST. I am amazed by your set up and all the work you put into the glider construction………… The cutting mat I have is a piece of polyethylene plastic I found in the trash. It was the right size for the 50" fiberglass roll.

F86_SABRE

oops ....sorry Jo..picked up the wrong person . Perhaps ST would be kind enough to reply? Thanks!

Reuben

sierratango

HI Reuben,

Honeycomb looks just like the structure Bees make in their hives. It is a lot of air. There is nothing wrong with air as long as the air is not trapped inside the laminate(layers of composite). When it is, that is called delamination and that is horrible!

The use of the vacuum and bagging film in this instance is not used to pull the air out of the honeycomb as it is used to allow the atmosphere to impart its' weight onto the bagging film and on to the part. The idea is to get the fine edges of the honeycomb structure to attach to the wetted out carbon it is attaching to.

Basically, the honeycomb acts like a shear web, much in the same manner the Airex or Rohacell foams work sandwiched between composite, When the finished part is twisted or the outer composite layers move in a different or smaller direction than that of the layer on the other side of the honeycomb, the honeycomb connecting the two layers tries to shear and doesn't like it, so it makes the part a lot more stiff. Because the honeycomb is air, it is lighter than the foam and it is used in more complex shaped parts. I will still be using Rohacell sandwich construction on all the wings and rudder.

As I said, part of my problem in this first fuselage was that I thought I could get the honeycomb to adapt to the first lamination with just Z-Lock bags filled with water. I was trying to avoid doing the vacuum on two separate occasions. That is why in some of the photos you see polyurethane 2lbs foam in the corners where the honeycomb didn't glue to the outer carbon layers.

I just read on MSN that 60 Minutes did a report on Lumber's Liquidators and the amount of Formaldehyde in their products is sky high and unhealthy. Their flooring is made in China. Maybe that is where my hardboard is being made. The stuff stinks. First time I have noticed this. Probably a different supplier than stuff I have purchased in the past. Perhaps saves Home Depot more for more profit margin?

I thought I only had to worry about the epoxy, acetone and denatured alcohol.

F86_SABRE

Thanks for the info. I might give honeycomb a shot if I can obtain a piece of honeycomb. Thanks again.
Reuben

jofunk

I may need to break my piggy bank open to finish this project. Or i'll just stick a butter knife in the slot to wiggle out a few nickels. I cut the fuse off the table. It seems very stiff. I will finish stringing, sheeting, and shaping it. Then i'll throw some glass on it.

sierratango

That's one ugly pig, one great looking project!

jofunk

I stood some balsa on end between the bulkheads to support the sheeting on the bottom since there are no stringers down there. There wasn't much room for fingers so to place some of the wood I stuck an exacto into the wood and it worked as an extension. After that was in I started figuring out some stringers. A kite string and T pin works well to get a straight line. Once the marks were on, I took a hacksaw blade and put a slice on every mark. The slice acted as guide to dremel out the slot with a 1/8' grout bit. The bit makes a perfectly snug slot for the 1/8" stringer. I put some sheeting on the nose so I could start shaping the foam blocks. The foam blocks will need a few coats of lite filler. You can't put the filler on thick over foam because it will never dry. The tops of the bulkheads for the center section got glued on and cut to shape…….. Now I just need to write the instruction manual for the center section.

sierratango

Second to last photo showing the stringers...beautiful work.

I really appreciate what you are doing.

jofunk

Vladimir made a few links for the servo arm connection. I picked up the servos yesterday. The arms are like chinese throwing stars. I started to make an end cap for the flying stabs. It is the same material that the stabs are sheeted with.

jofunk

Just figuring out where to mount the elevator servo. The link point is 8" away from the pivot and 3" below the centerline.

jofunk

The stabs got capped and sanded down. The best place for the rudder servo is above one of the elevator servos. I wanted to put it in the center bay under the rudder but it may interfere with the engine. The plate that was holding the bulkheads square got busted out and replaced with the rudder servo tray. I made a double pocket for the rudder servo because I am not sure from which side if the servo I want to link it. I am not sure what Vladimir will come up with for a nose gear and I want to keep the steering and rudder on the same channel. I don't want to be in a bind where something cannot be reversed. I wanted the linkage somewhere close to the sheeting. there will be a hatch there eventually for access to the servo and the link.

jofunk

I removed the chunk of stab where the link will mount. I may move it a little further forward. The amount of travel by using a longer arm may be a wash when the linkage needs to be moved forward.

jofunk

I urethane glued the hoz. stab linkage blocks in. The fits were snug and the glue did a good job of expanding into any voids. I tacked on a few runaway straps so they would not push out of position. Then back to some sheeting. The magic marker marks on the planks let me know which side has the accelerator sprayed on it. The sheeting went on pretty symmetrically. The final gaps look similar in size and shape. Once the bottom is to shape I will put some glass on it to harden everything.

jofunk

The little slivers of sheeting got filled in on the bottom of the nose. I started boxing in the area where the rudder linkage will run. I didn't box it all in because when I remove the hatch I will be able to see the front of the motor. I also boxed in the elevon servos so the sheeting has somewhere to stop. Vladimir made me a nice rudder linkage. The one on the left. I epoxied and lock nutted the bolt to a hard wood block. that got set into the rudder with some urithane glue. I taped off the perimeter this time to make the sanding go faster by keeping the glue mess off the sheeting.

LJE4357

My Feedback: (74)

Mark Frankel's A-5 Vigilante. I have the molds for the intake ducts. Before I toss them in the trash can, I thought I would ask if anybody wanted them. Email me ( [email protected] ) if you want them. It made for a really nice jet, very stable. EDFing them would really make it come alive.

jofunk

I hope they find a home. That would save someone a lot of work.

LJE4357

My Feedback: (74)

there gone.............wish somebody would buy the molds i have, bae hawk, l-39, f-106