Executive Jet- Build/Flying Thread

[EricJ320]

I decided since I was going to go to the trouble of putting on an entire custom paint scheme, it was wroth my time to cover the plane with Silkspan and Poly C.  It's a bit of work, but it makes the plane look sooooo good!  It puts a lightweight hard coating around the foam that makes it look more of a plastic plane than foam.  It does add a little bit of strength, but mainly protects the foam from getting dented and marred like foam is prone to do.  And gives a much smoother and more finished surface for the paint to go on.

Picture 1 was the first step.  I had to remove the decals, since I will be using them later they had to be cleaned.  I gently pulled them off, and then soaked them in Desolve It to remove the adhesive from the plastic sheets.  Once they had soaked for a few minutes, I scraped away the adhesive with my fingernails and paper towel.  The picture shows the end result with the plastic sheets ready to have spray on adhesive applied and remounted back on the plane once the paint is complete.

Picture 2 shows dry silkspan being applied to foam that has been pre brushed with Poly C.  You can put the PC on pretty liberally, and you don't really have to worry TOO much about the silkspan lying flat.  Just know that the more wrinkles you allow, the more coats you may have to apply, and more sanding that will be required. 

Picture 3 shows a full fuse picture as the first layer of PC is being applied to the entire fuse after it's been covered in silkspan.

Picture 4 shows the fuse from the front after the first coat has dried and ready for the first light sanding.

Picture 5 is after 2 coats of PC, 2 sandings, and then 2 or 3 quick coats with no sanding in between.  It all sounds like a tedious process, and it kind of is, but not as bad as you might think.  The PC dries pretty quickly, about 30 minutes for recoating, and an hour or so if you are going to sand in between coats.  A full coating only takes about 5-10 minutes to apply the PC.  The overall number of coats required really depends on two things, how well you want it to look, and how well you do the work.  The more coats gives it a more finished look, as well as helps hide imperfections not only in the foam, but in the workmanship.

Picture 6 is in the same stage as picture 5, it's just a closer picture looking down the fuse to show how all the wrinkles are eventually taken out, and how smooth the surface becomes.

[Flying_fox]

I have been wanting to try coating a foamy for a while, but keep chickening out, maybe what ever I replace the Estarter with will be my first Guinea pig.

Looks great! Any idea where you will be able to find enough smooth runway to fly it?

[Big Al]

What is poly c?  polycrylic? Where do you get the poly c and silkspan?

Thanks,
Alan

[Wash Out]

Polycrylic is sooo much easier to work with than epoxy it comes out lighter as well if I'm not mistaken.

[EricJ320]

Yeah, sorry I didn't explain that, on RCG you'll either see it called Poly C or water-based polyurethane (WBPU).  I use Miniwax's, but I am sure any brand WBPU that you can find at Lowe's or Home Depot will work.  I'd also recommend using light weight spackle to fill in any imperfections or injection mold spots on the foam before covering it.

As for Silkspan, it's a strong tissue like material for covering airplanes.  As far as I know, the only place that carries it in stock is M&N Hobbies, but I'm sure the others can order it.  

Hope that helps,
Eric

[EricJ320]

I have been wanting to try coating a foamy for a while, but keep chickening out, maybe what ever I replace the Estarter with will be my first Guinea pig.

Looks great! Any idea where you will be able to find enough smooth runway to fly it?

Give it a shot Drew, it's really not hard at all, and I feel it's worth the work.

I know once I am comfortable with it "the Hill" has plenty of room and runway to get this flying, especially with as much power as I am putting in it.  To get to that comfort level, I'm not sure, maybe KCRC. 

[Flying_fox]

Have you ever used light glass cloth with the poly?

[EricJ320]

Have you ever used light glass cloth with the poly?

I've heard of people using it, but I never have myself.  It will make it much stronger because you have to use so much more Poly C to fill the cloth, but it should accomplish the same task.  One down side would be the weight, due to the excess Poly C it can make it weight prohibitive to go that route, but that would have to be decided on a model by model basis.  This Exec. Jet could probably take it since it has such a big wing and raw thrust isn't the goal, rather speed.  But the P-51 I am also covering certainly couldn't take the extra weight.

[Flying_fox]

Ahh I see, so the silk span is relatively non porous, I have a entire gallon of WBPU here, may have to pick up some silk span and practice on something I have here 

[EricJ320]

Ahh I see, so the silk span is relatively non porous, I have a entire gallon of WBPU here, may have to pick up some silk span and practice on something I have here 

Yeah, it's not porous at all, it's literally like strong tissue paper.  It does come in three different weights, I use 00, the lightest.  But if you want more strength, and likely more work, you can go with the medium or heaviest weight Silkspan.  I believe M&N had all three, although they are 6 sheets lighter in the 00 since I went! 

I would do the heavier weight Silkspan before I went to FG cloth, just my opinion.  But if you are going to practice, make sure it's on something with curvature in it, flat is very easy, curves are where the difficulty goes up.

Eric

[Flying_fox]

I have an OLD 53" foam Cessna 182 kit that was originally designed for 30 size nitro, thought that would be good for practice, seem like a little extra weight wouldn't kill it, and if I completely screw it up I only have $25 in it. 

[Kerbob]

Great thread and great progress Eric and the silkspanning really makes it look more 'real' and I know it will also help keep the model looking clean and sharp over time whereas plain foam gets dingy. Do you know what the total amount of weight was that was added to the fuse in this process?
I was wanting to do this with my Acromaster but ended up not doing it because on that plane, every gram counts.  Also wasn't sure how it would impact a crash repair on EPP foam and I knew I would be crashing the Acromaster; I was right.    To repair compressed EPP foam damage to plane, they recommended poring scolding hot water over the foam.  Sure enough, from recent experience, it pops back out.
So, in addition to the weight, I'm wondering how the silkspanning will affect the overall strength of the plane (which I know will improve) and how it affects crash damage and repairs (which I'm thinking will be more difficult).

[EricJ320]

Thanks Kerbob!  I totally forgot to weigh the fuse before I started, but I can probably ask someone to do that and find out. I will weigh the wing before I start to get an idea at least.

You can alter how much weight it adds by sanding more or less in between coats. Obviously though you won't get as much strength the more you sand, but you'll still get the nice finish.

As for repairability, I don't think it would affect that much, and cross my fingers I don't find out. . It will certainly add to the amount of work needed if your goal is to restore the damage to an acceptable astetically pleasing finish, but I'd say that goes without saying. Both models I'm covering fall into the scale category, and I'd consider looks to be paramount to everything else, possibly even performance.  Of course there ways to fix that.....trash the stock fans and say hello to my 6 bladed fans and 350 watts per motor!

[EricJ320]

Since I got the SU-27 pretty much done and flying now, I got back on the EJ, at least a little.

I worked up the nerve to plug in the soldering iron again, after my little mishap a few weeks ago.  Since I am lengthening the battery leads to both ESC's I am adding 2 additional capacitors to the leads.  It's best to add them as close to the ESC as possible, so I exposed some wire close to the PCB.  I took the two capacitors and CA'd them together, I then connected the positive wires on the caps and wrapped them around the positive wire, and the same with the negative ones as well.  Once the wires were wrapped I dropped a dab of solder on each one.  To finish it up I will add a large piece of shrink wrap to insulate the connections. 

In case you are wondering, the caps help protect the ESC from voltage spikes from longer battery leads.  As you raise and lower the throttle, voltage is drawn into the ESC, as you then close the throttle, the longer the wire the more voltage that is in the wire on it's way to the ESC.  Think of it like a running faucet with a long pipe full of water, if you slam it it closed, you sometimes can hear the pipes rattle.  The longer the pipe, the more force and momentum it carries and the hard the pipes will knock.  It's the same with the electricity running in the wires to the ESC.

[PerformanceModelAviation]

Hey Eric, if ur using the CC ESC I don't think you will need to worry about the caps and the battery lead length.. I have about 12 inches plus on my large comp plane and have not had any issues.. But we don't slam the power on and off either... Don't forget to twist the ESC wires to  motor this will help kill any EMI. Also you might want to put a choke on the lines from esc to RX to prevent any emi into to the rx from the backside..sounds like your making headway..