wkevinm

I thought I would post a couple pictures of a Q500 fuse mold I am building . I am building the mold for personal use, the vac bagged wing will be an MH17 airfoil. I have not built a mold since a F1 fuse and wing mold many years a go so this was like a new thing for me, but to date the hardest part has been getting a finish on the plug with PVA that I am happy with.

I am using Ed Smiths method, I think Ed called it a bathtub mold, that being the joint line is at the bottom of the fuse.

The parting board was made of ¼� melamine board, sprayed with klasskote primer, waxed and PVA'd. The fuse was placed in the board ¼�. Again I used Ed Smith’s method with a front plate for easier extraction of the male part.

I sealed the parting board to the plug with epoxy / balloons (this was insufficient at the end of the day since I got leakage and now joint to clean up.

The fuse was built up, glassed, primed, painted, waxed, PVA’d before placing in the parting board frame.

I used the following to make the mold

1st layer – East epoxy, with west graphite powder for black color.
2nd. Layer – 2 ounce cloth, East epoxy, graphite
3rd layer, 6 ounce cloth, east epoxy
4 th layer, 10 ounce cloth, east Epoxy
5th and last layer, 1.5 ounce mat., East epoxy

Along the way I used epoxy, balloons, fiber for 90 degree fill and sharp corners.


At the point I am now at, I removed the top half of the mold with plug from the parting board. I have an issue, in that I now want to clean up the joint line. There was some leakage at the parting board line and since I intend on painting in the mold, I want this line as clean and sharp as possible. Any suggestions on how I can do this without removing the plug, which I prefer not to do until the end.

The picture that shows the top half of the mold is how it came off the parting board and the PVA has not been cleaned off yet.

KM

soarrich

My Feedback: (98)

Interesting way of doing it. Bob Dodgson did something similar with what he call his Taco shell fuses. I had a Midwest Attacker that was a two part foam fuse like this, parting line a little higher though. The thing I liked about the Attacker was you installed the radio before you put the top halve on, made it a very easy installation, same the the Taco shell fuses.

Ed Smith

Kevin,

I am assuming the mold split line has a ragged corner. I know you do not want to remove the plug but you may have to. May I suggest this? lift the plug about a 1/2" in the mold. Whatever you used as the gelcoat, use it to fill up the ragged corner against the sides of the plug. When cured remove the plug. The insides of the mold that were against the plug will now be restored. There may be a line but this can be polished out. The excess filler standing proud of the mold flange can be sanded down flush to restore the mold sharp corner.

This is a bit of a rescue job so Good luck.

Ed S

wkevinm

Ed, thanks for the comments. The edge was not so much ragged as it had epoxy that was proud from it leaking past the parting board seal. To remedy I rounded out a hotel key card and inserted between the plug and mold, I used this as a backing to alow me to trim this excess flush with the parting line. Once I split the whole thing I will try to clean up the flange if necessary.

Here is the top half after I cleaned up the PVA and the flange. I applied 3 coats of wax and will spray with PVA prior to applying a coat of East epoxy with graphite.

Also I attached a picture of the V-tail and the parting board (in progress). Once I pull the plug out of the mold I will finish the V-tail to fuse fit.

KM

wkevinm

I have finished the mold and am now ready to prepare by waxing (3 coats) and spray with PVA.

The layup schedule I will use, unless there is some experienced advise to the contrary will be;

Step 1
paint mold with KlassKote

Step 2
epoxy / cabosil / fiber sharp corners
1 layer - 3/4 oz
1 layer 2.5 oz
let dry

Step 3
1 layer 2.5 oz
1 layer of 6oz
1/16 balsa reinforce on sides for stiffness
6 oz CF to reinforce at Gear attachment
6 oz CF to reinforce at tail
6 0z CF to reinforce at nose.
vacuum bag

Average thickness - 12oz
Average at stress points - 18oz

KM

daven

My Feedback: (1)

Are you doing a single color of klasskote or multiple colors?

wkevinm

Dave

Just a single color, it being my first fuse and since I am using PVA until I get confidnce in pulling out of the mold with only wax. This mold is quite deep and the configuration at the tail I assume will require as little friction as possible to get the fuse out.

Do you have any comments on the layup schedule; is this enough or too much?

KM

Ed Smith

Hi kevin,

I would suggest that you have too much cloth. The 3/4oz will do nothing for you. I use one layer of 2 oz, .5oz carbon in the nose and final layer of 6oz. My fuselages coming out of the mold weigh 6oz unpainted. This is with the firewall, landing gear plate and wing mounting blocks installed, I install them in the mold.

Ed S

wkevinm

Thanks Ed,

I will modify the layup to better match your configuration.

KM

daven

My Feedback: (1)

I've never laid up a fuse Kevin, still use wood

wkevinm

Dave,

I have decided to go with a glass fuse for a couple of reasons. In Canada (CPPRA) we typically race off of grass, or some semblance to grass at some fields. I have noticed the molded fuses seem to withstand the rough landings a bit better than the wood fuses, I am tired of relacing the gear block and the tail sections of my wood fuse, I hope the molded fuse is more durable.

Secondly, I have seen how the NemeQ fuse is done, very elegant (simple and efficient). It appers very light and yet withstands rough landings, I hope to emulate at least the weight and strength of these, even though the finish may not compare.

I have molded and pulled lots of F1 fuses in the past (20 years go), but have forgotten most of the steps, and those required lots of sanding, filling and the like I hope a paint in the mold will eliminate most of this tedious work.

Here is a picture of the mold painted with Satin White Klasskote, ready to start laying it up, I will use West epoxy dyed white for the first layup to match the paint. I think the first one will not be done with a vacuum bag for simplicity.

KM

Ed Smith

Hi Kevin,

If using west Systems epoxy I would suggest using the slowest hardener available. It takes me 2 1/2 -3 hours to lay up the fuselage, place in all the wood parts, close the mold and deal with the seams. West Systems epoxy will not stay workable that long. I no longer use Wests epoxy for that very reason. I use MGS resin, The slow hardener will allow a 5 hour working time. Apart from that West and MGS are of the same high quality.

Ed S

wkevinm

Ed
Thanks; I have trid to find MGS here in the West but cannot find any, so I have been using West and most recently East (made in Montreal I think). I know I have read in earlier posts that you close the mold wet and you rely on a overlap on alternate sides. I would like to copy this procedure. Is there a post already that desribes the procedure. My current plan will be:

Layup schedule:
-Klasskote satin paint (white)
-2.5 oz with West Epoxy, white dye.
- 6oz CF at stress areas; gear block, tail, and firewall/nose
- 6oz cloth with 1/2" excess for joint.

Procedure:
1. Lapup as above, continuous, no pause for curing; on alternate sides have excess material (6oz) proud of the flange to give an overlap aout 1/2" (probably less towards the back).
2. Join the two parts when the epoxy is starting to stiffen, not cured. ( mix several batches and I can lower temperature of room to extend epoxy pot life, although this increases viscosity as well).
3. Apply additional epoxy to the side that will take the overlap. (do not wet the excess cloth)
4. Add a light cabosil/ epoxy trace at the joint line.
5. Extra cabosil at the tail, since it will be difficult to lay down a cloth seam.
6. Install the firewall into the main mold with cabosil. (the firewall has been routed to provide a key around the 1/4"ply). Attach front plat to hold firewall in place.
7. Place the bottom mold onto the main mold, pin and clamp.
8. With long handled roller, lay down the 1/2" cloth.
9. Lay in Gear block CF

KM

wkevinm

A picture of getting ready to layup the first fuse, getting the parts ready and the CF cloth pieces cut.

wkevinm

I pulled the first Q500 fuse tonight.


Layup schedule:

KlassKote Satin White
1 layer 2.5 oz FG
1 layer 6 oz FG
plus an additional 1 layer of 6 oz on the sides joined with this layer as well
CF at Firewall to Gear block and front wing block, sides only
CF at tail section (sides only)
1/4" firewall
1/8" gear block with CF (2layers)
1/8 wing blocks front and rear layed over CF

Cleaned off PVA

In general I am happy with the product, there are a few blemishes on the fuse due to some voids.

Total weight 8.3 oz, still needs to be cleaned up then ready to bolt on engine, tail, gear and wing.

KM

KM

daven

My Feedback: (1)

Looks good, layups go better with Moosehead

Your definately Canadien!

If wood fuses aren't holding up, maybe you should work on your landings

wkevinm

Dave

No doubt some of the landings are to blame, and not the wood fuse or perhaps Moosehead during building is somehow related. Now if I drank American beer I might not have the same problem.

Kevin M.

AllanU

Kevin

I can't wait to fly it! It will be ready for Saturday won't it.

Thats awsome. Now I am going to have to work on my plug some more.

Remember that exchange rate eh, 2 US Beer = 1CAD Beer.

Al

ptxman

My Feedback: (2)

1) Aircraft Spruce & Specialty 'out east' now brings in most anything shown in the USA catalog, they will ship MGS resin inside Canada at reasonable Canada Post rates. I think the 4l kits fall unde some magic volume for hazardous... you'll have to check.

2) Airheart 'out east' is the Canadian dealer. They probably prefer 5 gal pails but will ship smaller qty's & have the other MGS goodies
http://www.airheart.on.ca/distributing/aboutus.html

3) Alberta Plastics & Paint (Calgary) handles MGS, at least they did. I suspect they are a re-bounder for Airheardt, but bit closer to home.

West epoxy has a lower HDT (heat distortion temp). Its not bad, but you can do better with MGS imo.