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Black Magic VF3 E build thread!

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Old 08-29-2007, 09:23 PM
  #26
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Default RE: Black Magic VF3 E build thread!

Mike, The picture of this honeycombed wing shows a spar along the back of the wing between the honeycomb and aileron line that is not shown on the wing plan that you sent me a pdf file of. Is this optional or should it be added to reinforce the honeycombed tip? If I need to add it, what material should I use- spruce, balsa or lite ply?, and can you give the the length measurement.? Thanks,

George
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Old 08-30-2007, 11:37 AM
  #27
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Default RE: Black Magic VF3 E build thread!

It's optional, but I use it anyway. It can be just a piece of 1/8"x1/4" balsa, but I like to sandwich .007" carbon between 2 pieces of 1/16" balsa and make the 1/8" x 1/4" spars from that. The length is 16".

I'm about to get neck deep in this build thread......

-Mike
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Old 09-18-2007, 12:41 PM
  #28
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Default RE: Black Magic VF3 E build thread!

ok let's roll......

Capping the cores

First, trim the LEs of the wings, stabs and fin down fairly close to the core. Sand this flush using either a block sander or long, stiff bar sander. be careful to keep it all straight and true, and don't sand too much.

Cut out a piece of capping for each core. The Wing and Fin LEs are made from 1/2" contest balsa, and the stabs are capped with 3/8" contest balsa. Cut these a little oversized so you can trim them back.

Glue the LE caps in place with polyurethane glue. All you need is a thin film, just enough to be damp. Anything more is dead weight. Spread it on with a finger and then go over it with a paper towel. if it's just damp, it's perfect.

Tape the LEs in place with masking tape in numerous locations. Pull the tape snug so there is no gap.

Let the cores sit for 6-8 hours before trimming.

-M
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Old 09-18-2007, 12:51 PM
  #29
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Default RE: Black Magic VF3 E build thread!

After a few hours, you can remove the tape from the LEs.

Trim and sand the tips flush at this point. Take care to keep the tip face at a right angle to the center line of the wing. Rough sand the roots flush as well. DO NOT final sand these, just get them close.

Make marks at the center of the LE capping where the core meets the capping, and one mark at the center of the TE capping. Using a straight edge, make a mark on the face of the LE capping at the root and the tip.

Use a straight edge to make a line donw the center of the LE using the reference marks. This will give you a reference to sand to.

Now prepare the tips. the wing tips are made from 2" contest balsa blocks, hollowed as much as possible. Roughly trim it to shape.

The Stab tips are made from 1" contest balsa.

On the fin tip, I normally stack 2 pieces of 1" contest balsa, and sandwich a piece of .007" carbon between them. This stands up vertically and gives this piece a lot of stiffness.

Using the same method as the TE with the polyurethane glue, attach the tips and tape firmly in place with masking tape.

Let all of this cure overnight.

-M
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Old 09-18-2007, 02:47 PM
  #30
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Default RE: Black Magic VF3 E build thread!

After the caps have cured overnight, it's time to sand them to shape.

I suggest a 14" sanding block (or so) with fresh 80 grit sticky back paper. This takes a lot of the work out of this step.

Start by sanding the tips flush with the wing panel. be CAREFUL that you don't sand into the skin here. Block control is critital. Just take your time and pay attention to the angle of the block. If in doubt, apply some masking tape to the skins and that will "warn" you if you're getting out of shape.

On the leading edges, first sand the LEs flush to the wing or stab or whatever, at about the same angle. Again be very careful here.

After The LEs are "blocked" to the contour of the core, start turning the corner, a little at a time, toward the center line. Keep it round.

Once you have achieved a roughing in of these shapes, STOP. Don't do any more until completion of the plane.

-M
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Old 09-18-2007, 02:56 PM
  #31
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Default RE: Black Magic VF3 E build thread!

Now we need to mark and cut out the control surfaces.

The best way to do this, starting with the wing, is to make a poster board template. If you just free hand it, you're less likely to get it equal.

Mark out the cut lines, the relief lines for all of the capping, and the servo boxes.

It's critical to extend the wing capping into the wing about 2 1/4" or so.

Make all of your marks on the bottom and leave the cores in the top shuck for cutting.

The best tool for this job is a band saw. You can cut it out by hand if you mark both sides and trim/sand to the lines, but a band saw makes this job painless.

Make certain your band saw table is 90 degrees to the cutting blade. begin your cut carefully and cut about 1/8" away from the actual outline. This will allow you to sand to final position for a perfect fit.

Cut out the ailerons, and then trim away the excess material.

-M
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Old 09-18-2007, 02:59 PM
  #32
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Default RE: Black Magic VF3 E build thread!

Sand the cores and ailerons fulsh to the cut lines. ALWAYS use a hard bar sander with fresh 80 grit paper for this job.

Take special care not to screw up the angles. It's ok if it' off some, but not a lot.

Make a sharpie mark on your aileron to not the center of your hard point. This makes life much easier later on.

Don't sand the ends flush yet, leave a little to sand away.

-M
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Old 09-18-2007, 03:05 PM
  #33
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Default RE: Black Magic VF3 E build thread!

Lastly (for now) we need to finish capping the wings and ailerons.

Make the wing capping out of 1/4" contest balsa, and the LE of the aileron from 3/8" contest balsa. Make sure that the aileron capping is well oversized.

Using the same glueing methods outlined earlier, glue and tape the capping in place.

Place the ailerons down face first on a table. if you lay them on thier sides, they could possibly warp. Adjust your tape so they stay straight.

After a couple of hours, sand the ends flush and install the end caps on the ailerons and wing. These are made from 1/8" contest balsa.

-M
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Old 03-11-2008, 04:45 PM
  #34
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Default RE: Black Magic VF3 E build thread!

Hi Mike,

Did you finish this build?

Cheers
Jason.
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Old 03-13-2008, 09:58 PM
  #35
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Default RE: Black Magic VF3 E build thread!

Got kinda sidetracked. Close, very close. It's built, not painted yet.

I'll get back to this thread when things die down a bit. I said that before didn't I? Soon anyway.
I won't go into any gory details but let's just say it has been an interesting 6 months or so. I've learned a lot. Actually I would do quite a few things differently now, and I'll share them with you all soon. Nothing critical, just argueably better, lighter, more simple.

-Mike
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Old 04-08-2008, 12:02 AM
  #36
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Default RE: Black Magic VF3 E build thread!

G'day Mike,

What Balsa sheet weights should I be selecting for the VF3E?

-36 pieces 1/16x4x36" contest balsa (LIGHT!)
-2-3 pieces of 1/16x4x48" contest balsa (LIGHT)
-3 pieces 1/8x4x36" contest balsa (LIGHT)
-2 pieces 1/4x4x36" contest balsa (LIGHT!!!!)
-2 pieces 3/8x4x36" contest balsa (you get the idea)
-1 piece 1/2x4x36" contest balsa (ditto)
-1 piece 1x4x36" contest balsa (getting the picture?)
-1 piece 2x4x36" contest balsa (this one can make or break ya)

BTW how's my kit coming along?

Cheers
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Old 04-08-2008, 01:25 PM
  #37
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Default RE: Black Magic VF3 E build thread!


Quote:
ORIGINAL: Aussie_Knife_Edge

G'day Mike,

What Balsa sheet weights should I be selecting for the VF3E?

-36 pieces 1/16x4x36" contest balsa (LIGHT!) 12 grams or less
-2-3 pieces of 1/16x4x48" contest balsa (LIGHT) 16 grams or thereabouts, not as critical
-3 pieces 1/8x4x36" contest balsa (LIGHT) 24 grams or less
-2 pieces 1/4x4x36" contest balsa (LIGHT!!!!) 50 grams or less
-2 pieces 3/8x4x36" contest balsa (you get the idea) less than 70 grams
-1 piece 1/2x4x36" contest balsa (ditto) less than 100 grams
-1 piece 1x4x36" contest balsa (getting the picture?) 200 or less
-1 piece 2x4x36" contest balsa (this one can make or break ya) less than 400...the lighter the better
BTW how's my kit coming along?
-Shipped [8D]

Cheers
Jason.
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Old 04-08-2008, 04:20 PM
  #38
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Default RE: Black Magic VF3 E build thread!

Thanks heaps Mike! You're a champ mate.

I found Dean's comments on the glass used on VF3E twins interesting. I have .75 Oz glass cloth and was thinking I needed to buy some .5 Oz. Might hold off on that now...

Cheers
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Old 04-08-2008, 07:04 PM
  #39
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Default RE: Black Magic VF3 E build thread!

HI Jason,

The .5 cloth that I've used in the past had a more open weave than this .7 cloth, which seems to take a lot less microballons to fill. Also the application was much easier. It took me less than 45 mins to do one side on both (2) planes this morning. You also seem to get a less "lumpy" result and sands smoother with less effort, also it would seem like you will be less likely to sand thru the cloth when your prepping for the primer. From my experience the biggest weight gain is in the primer. My weight gain on my personal vf3 just from primer was around 3 oz with the fiberglass added around 2.65 in addition for a total of around 5.5 for the glass + primer. This was also about true for the electric v2 I painted a year ago.

The interesting thing was the color on that electric v2 (look back on the v2 thread) add less than 1.5 oz. I don't have an exact number but I think you end up using less than 3 sq yards of cloth (actually what ends up on the plane) so the weight difference might be less than .5 oz anyhow. Which you could make up by needing to use less primer - maybe a lot less ?? I guess we will find out in the next week

I'll have 3 vf3s to paint shortly !!!

best regards mate,

dean


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Old 04-08-2008, 07:50 PM
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Default RE: Black Magic VF3 E build thread!

G'day Dean,

When you put it like that regarding the weight difference it makes perfect sense. Sometimes it's hard to see the forest through the trees.. lol

Happy glassing...

Cheers
Jason.
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Old 04-08-2008, 08:08 PM
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Default RE: Black Magic VF3 E build thread!

Hi Jason,

I am down here in the shop trying to get a better estimate on the actual sq inches of cloth used to fiberglass the vf3.

and it's more like 1200 sq inches or actually less than a square yard of material, so if that's correct your .75 cloth is only adding about .25 of an once....

That is based on a rough estimate of a 10 x 60" area x2. so the weight increase seems like it's even less than I thought. Mike what do you estimate for the actual cloth on the plane... ???

I know I trimmed off a lot of cloth that's now in the scrape bag....


later friends, dean
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Old 04-10-2008, 11:21 AM
  #42
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Default RE: Black Magic VF3 E build thread!

hey guys,

the side area of the plane is roughly 880 square inches. Now the part that's glassed is a bit less, and then you have the curves and BS to also take into account.....

I'm fairly good with math, but my calc is a bit rusty. So I can guess. I guess about 1200 square inches, more if you glass the rudder and exhaust area (don't glass the area under the chin cowl on an electric!)

And I totally 110% concur with Dean on the cloth. I have been using the .5 glass for a long time, but lately got some .7 from CST and it's SO much easier to work with, and I am not sure about the weight.

Here is my take on the weight:

From what I have seen over the years, no matter what you do, your base is going to be X amount of work and X amount of weight when you're all done. Mark Atwood did some tests on this and came to pretty much the same conclusion. But there are 3 steps where you can make a significant difference:

1. Seal the plane and THIN THE RESIN
2. Use micro balloons to initially help fill the weave
3. Do NOT get lazy sanding. Leave that primer in the floor

From there, use a single stage paint and don't use a clear coat unless you're doing the natural carbon canopy look.

-Mike
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Old 04-10-2008, 09:42 PM
  #43
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Default RE: Black Magic VF3 E build thread!

G'day Mike,

When sealing the balsa grain before glassing or applying epoxy, I note that you use either hairspray and or Balsarite. What are your thoughts on using Dope to seal the grain instead? Obviously it can't come into direct contact with the foam otherwise it would melt away... lol [:-]

Yourself and Dean speak of thinning the resin with acetone anyway when glassing wings and fuses so I would presume dope is fine to use. It's also more readily available here in Australia too....

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Old 05-02-2008, 12:45 AM
  #44
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Default RE: Black Magic VF3 E build thread!

Hi Mike,

What do you suggest regarding the following items for the VF3E?

1. Spinner and adaptor suitable for an AXI F3A?
2. Axles for the main wheels when using your supplied UC?
3. Suggested main wheels. Size, brand etc?
4. Suggested tail wheel?

Regards
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Old 05-02-2008, 07:27 PM
  #45
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Default RE: Black Magic VF3 E build thread!


Quote:
ORIGINAL: Aussie_Knife_Edge

Hi Mike,

What do you suggest regarding the following items for the VF3E?

1. Spinner and adaptor suitable for an AXI F3A?- don't know...but if you can get the 8mm threaded shaft, same as YS
2. Axles for the main wheels when using your supplied UC? CH aluminum
3. Suggested main wheels. Size, brand etc? 2 1/2" dubro super light
4. Suggested tail wheel? MK

Regards
Jason.
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Old 02-26-2009, 06:31 PM
  #46
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Default RE: Black Magic VF3 E build thread!


Quote:
ORIGINAL: MHester

I also have vacuum bagged the cores with honeycombing. If you bag the whole shuck you can get away with it, but you can't pull a lot of mercury or you'll still crush the wing.


-Mike
Hi Mike,

When you say not to pull a lot of vacuum on a honeycombed wing, just how many inches are you talking about?

Regards
Jason.
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Old 02-27-2009, 09:33 AM
  #47
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Default RE: Black Magic VF3 E build thread!

5-6 is about all...any more and you'll crush the tips. And that is the shuck, not just the wing....bag the whole shuck.

-Mike
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Old 07-12-2009, 10:28 PM
  #48
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Default RE: Black Magic VF3 E build thread!

Hi Mike,

Do you normally honeycomb the stab and fin/rudder cores?

If you do, do you have any pictures of this?

Cheers
Jason.
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Old 07-12-2009, 10:59 PM
  #49
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Default RE: Black Magic VF3 E build thread!

How big of a deal is it to convert a B< V2 to Electric?
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Old 11-30-2009, 12:24 PM
  #50
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Default RE: Black Magic VF3 E build thread!

Has this build thread just not been finished, or has it been moved?
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