RE: SIMLA BUILD THREAD
 

Bill,

Are you using the urethane to attach the glass cloth or did you use finishing epoxy and now filling-in with the urethane?

Thanks,
Richard

RE: SIMLA BUILD THREAD
 

OK guys:

Here are some pictures of the tube and sleeve in my Simla with measurements. It is a 1" PBG tube and sleeve set. The 1" is just a reference name for their product. It does not mean the exact size of the tube or sleeve. If we go by SAE (Inches) the tube OD is 31/32nds of an inch and the sleeve is 1-1/32" OD. Hope this helps for those who are using the PBG tube and sleeve set. I will have to look back through my build photos and see if I had to modify the holes. I'm not positive I had to do anything to the holes. Stand by.

Thanks:

Kevin Clark

RE: SIMLA BUILD THREAD
 

Guys:

Found the clue in a couple of pics of my build that reminded me that I did have to ream out the holes 1/32 so the sleeve did not pinch the tube. I will let you guys take a look at these pics and see if you can see what I used for the tool. It was very simple and I had several of them around. It worked perfect for reaming the holes exactly. (Hint) I did it all by hand. I used a test piece of balsa first for trial fits.

Thanks:

Kevin Clark

RE: SIMLA BUILD THREAD
 

Richard, I use the urethane clear to apply the glass to the balsa surfaces. I work out any bubbles or wrinkles carefully because the 0.5 oz. glass is sort of delicate. I let the application coat set up thoroughly before I apply the second coat( again by brushing it on) on the heavy side. When it sets up, sand with 180 grit sand paper trying to avoid sanding through the glass. This will give a fairly smooth surface so that one sprayed on coat of urethane clear followed by sanding with 320 or 400 grit sand paper should give you a very smooth ready to paint surface. I know it's a lot of sanding but the end result is well worth it. BTW, this system produces a very hard, durable finish.

RE: SIMLA BUILD THREAD
 

Well, I see what looks like a file, which wouldn't have done the job exactly. And a couple yellow tubes that I can't identify. Am I getting close?

Richard

RE: SIMLA BUILD THREAD
 

Bill,

I was wondering how that would work with the carbon veil and Ultracote. (I guarantee that, if I lived at sea level, I'd paint. Up here, we have to overpower everything.) I've got some clear urethane, so will check to see what happens if I apply it to a test piece and then iron on some Ultracote.

As always, many thanks.

Cheers,
Richard

RE: SIMLA BUILD THREAD
 

Kevin, that appears to be a half round file in the background. One of the ideas that I was considering was to take a piece of the adhesive backed 180 grit that I useand attach it to one end of the wing tube to make a reamer for the sleeve holes in the ribs and fuselage, especially since you have indicated the difference between the two sizes of sleevesis relatively small. I guess I'll find out when my tube and sleeve arrive.

RE: SIMLA BUILD THREAD
 

Your on the right track. The self adhesive 180 grit comes in perfect rolls. I peeled off the roll until I got to the desired diameter and used it in a rotating motion (like turning a screw) by hand to ream out each rib and fuse hole. It did take a while, but I was able to make the holes perfect. I tried some test pieces with power equipment, but I could not reproduce it every time, like I could by hand.

It worked for me, so I do not know why it would not work for you guys. I did several test on scrap balsa pieces until I was happy.

Kevin Clark

RE: SIMLA BUILD THREAD
 

Richard, I'm not sure how the urethane would work with the carbon veil and Ultracote, but my guess would be that it would probably work quite well. Let us know what your test turns up. And yes I admit that here in Florida we are at or in some cases below sea level and that I even have some 60 size aircraft that came in at 10 lbs. but not necessarily because of the way they were finished. Redundant batteries, over sized engines(OS 75 AX as opposed to a 60 sized engine) and not paying particular attention to weight during building and finishing have contributed to my obese aircraft.http://www.rcuniverse.com/forum/js/f...sn/biggrin.gif

RE: SIMLA BUILD THREAD
 

Slower, by hand is often more accurate than quick by machine. Your method is exactly what I was planning on doing. Thanks for the affirmation. It's nice to know that something actually works before one makes a mess by trying something unknown.

RE: SIMLA BUILD THREAD
 

With "A LOT OF BUILDERS USING BIGGER ENGINES" Will and does this plane qualifi for the Senior Pattern Assciation? I'm trying now to locate a Astroflight 90 FAI Cobalt motor.Sorry to get off the build thread.
stefanP

RE: SIMLA BUILD THREAD
 

stefanP

The plane was designed and built in late 1964-1965, so yes it qualifies for both 'regular" SPA competition, and "Antique", (pre-1968). The problem is the power. I would love to see how Simla flies on a .60, but we haven't done that yet. I'm pretty sure it wouldn't have much in the way of vertical performance. For aerobatic flying, (which is what it was designed for), I think you need a .90 2-stroke.

UStik, Burkhard from Germany), is probably very frustrated right now, because his simulations show the plane should be aerobatic with a .60. Someday we'll see.

Duane

RE: SIMLA BUILD THREAD
 

As you can see from the pictures of the boxy fuselage prior to sanding, this plane needs a lot of sanding...especially if you want to get that "slinky" Simla look, which is quite round. An electric or "orbital" sander is a "must" I would say to keep your spirits up so you can see yourself making progress.

I mentioned my trusty orbital sander, which my father or I has always had as far back as I can remember. I didn't think I'd do this, but "what the heck"...why not.

Behold, this is a 1959-1960s vintage orbital sander from "Thor". It is on its second cord, and the switch doesn't work, but it's the "greatest thing since sliced bread" for transforming boxy blocks of balsa into sophisticated fuselage shapes, and every plane since my first scratch-built Phoenix 1 to the Simla has been sanded by this sander. From A-Z, (there were others I don't have pictures for).

RE: SIMLA BUILD THREAD
 

I spoke to Jeff by e-mail about the wing tube. Here is part of his response:

I'm using a smaller tube with a thicker wall thickness. A one inch would have been too intrusive on the spars and reduced the amount of wood between the spars and the tube holes.

Not supplying the tube is a good idea. I had considered it before but wasn't sure how that would be perceived by my customers.

Duane

RE: SIMLA BUILD THREAD
 

Bill,

If the &^$@#! urethane (Deft brand) ever dries, I'll be happy to let you know how the test goes. After drying overnight, the first coat was still tacky this morning. I suspect you're using a different urethane.

Spent much of today creating right triangles from ply, and attaching magnets, to be used for aligning the fuselage. And more sanding on various parts. At least I'm now ready to button up the stab and the fin. (Came real close to sheeting the second side of the stab and elevator before remembering that I needed to add and shape the hinge mounting points.)

Cheers,
Richard

RE: SIMLA BUILD THREAD
 

I can only speak for myself, but I would rather the kit engineers and developers determine the appropriate tube and sleeve and the supply it with the kit. Of course a price adjustment would be in order, but hey, if you want to use the best parts you expect to pay for them. Besides, switching to the use of a CF tube and sleeve is already adding $70.00 to $80.00 to the original price of the kit. From what I have seen of large R/C aircraft kits what Jeff is charging plus the addition of the cost of aCF tube and sleeve ( in any size deemed appropriate) would be reasonable. That way the kit would have the best in technology and the customer would not have to order and subsequently wait for additional parts. Assuming that the tubes and sleeves could be ordered in bulk a price reduction on them my be possible as well. Just a few thoughts off the top of my sometime delusional headhttp://www.rcuniverse.com/forum/js/f...sn/biggrin.gif!!! BTW I was able to get the fuse and tail feathers glassed this weekend. looking pretty good even if I do say so myself. Fun, fun,fun..........

RE: SIMLA BUILD THREAD
 

Richard, I am using Dupont automotive products for clears and base coat colors. There are a number of different grades of urethane clear in their product line any one of which will do a more than adequate job. I am currently using their high end clear just because I had it lying around. I suspect that their high speed spot repair clear would work quite well if you were in a big hurry or live in a cool climate. Remember this stuff is used on automotive paint jobs so it is hard and very durable as well as fuel proof.

RE: SIMLA BUILD THREAD
 

Thanks, Bill. I'll look for the Dupont items in town, although there are so many things that just aren't available in Colorado Springs. (Reminds me of when I was stationed in Fairbanks, AK. Shops often suggested that I look in Anchorage - - a multi-hour drive that I was NOT going to attempt at 45 degrees below zero - - or, better still, Seattle - - a multi-hour flight.) I'm even going to have to shop online for blue cream hardener. Every place has red; but no blue. Including the store that sold me the filler.

By the way, I fully agree with your comments about kit parts. I would have been happy to pay extra for the best/lightest wing tubes and sleeves, knowing that they would fit. Now I'm wondering if the $80 worth of CF tubes from Radio South RC is going to cause excessive trouble. Although Kevin seems to have been successful with it. I detect another learning experience.

Cheers,
Richard

RE: SIMLA BUILD THREAD
 

I have a quick question for Kevin. In Jeff's forum you stated that your Simla came in at 8.43 lbs. Was that flying weight, dry weight, or something else? I have weighed everything except the wing including the radio, engine, etc. and I am at 6.91 lbs before any finish work. I am estimating 9.5 to 10.0 lbs by the time all is said and done. I am hoping that I can reduce that some. Only time will tell I suppose.

RE: SIMLA BUILD THREAD
 

You didn't ask, but mine came in at 10.5lbs, which I was disappointed with since my wing was a full pound lighter than Kevin's at one point. Iron-on covering saves weight. I'm pretty sure that was "dry weight". I don't know how he did it.

Duane

RE: SIMLA BUILD THREAD
 

Let's see, leave out every other rib, bore holes in the fuse and tail feathers, skip half the hinges,drill holes in the servo cases, so on and so forth............http://www.rcuniverse.com/forum/js/f...sn/biggrin.gif

RE: SIMLA BUILD THREAD
 

It's interesting you'd say that...I've been known to drills holes in the doublers, and remove some of the wood in the ply ribs on the Simla, (you'll see that when we get to the wing). My first King Altair scratch-built efforts were built before I learned the value of a light plane. The balsa came from one of the large mail-order companies familiar to everyone, (don't buy wood there), and was heavy as a stone. The plane was WAY to TAIL-heavy to boot.

To correct for this, (not realizing it was the wood), we went all out trying to save weight in the tail. My King Altair prototype even had a sheeted foam top block. Unfortunately, we tried so hard to lighten the tail, that I wound up having to add, (lots of) weight to the tail.:eek:[&o] Even recently when I moved the rudder servo to the tail, it STILL behaves like it's nose-heavy in flight.

You have to remove weight evenly to make the thing balance without adding weight.

Duane

RE: SIMLA BUILD THREAD
 

Bill,

Does your clearcoat use a catalyst? The *only* automotive paint supply store in town said the clearcoat (urethane?) they sell requires a catalyst. (They don't sell Dupont products, which does include a one-part clearcoat.)

Thanks,
Richard

RE: SIMLA BUILD THREAD
 

Richard, yes the clear I use is catalyzed. I am using Dupont ChromaPremier 74500S productive clear coat with ChromaPremier Pro 14306S productive slow activator. IMHO a catalyzed urethane clear coat is more durable as well as harder than uncatalyzed clears. Then too, catalyzed productstend to harden chemically as opposed to just air drying. Also, the slower the activator the stronger the end productin most cases including such things as epoxy glues,epoxy paints, and even CAadhesives.PS- I should think almost any manufacturers catalyzed urethane clear would work adequately. In forty + years of automotive paint work I have used many products from many different manufacturers and despite some small preferential differences the end result is pretty much the same. I happen to be using the Dupont products because they were readily available to me. Any good two part urethane clear coat should do. Just be careful to mix according to the manufacter's instructions.

RE: SIMLA BUILD THREAD
 

Bill,

Good. At least I know I can get that type of clearcoat here. BTW, do you sand and fill before the glass and clearcoat, or after? I am *assuming* that it's better to prep the surface as much as possible before glassing.

Possibly foolish question: What's the advantage of the clearcoat over, say, finishing epoxy, such as West Systems? Less weight? Easier to apply?

Cheers,
Richard