Bill,

I notice that your build shows no evidence of primer, and only a couple spots of what I think is filler. Is this because you sanded all the primer away because you didn't have any high/low spots? (Note that if that's the case, I'm going to throw myself in front of a bus. My stab is gray all around, and likely to get worse now that I've sanded out all the cracks in the primer and starting over.)

Cheers,
Richard

Duane,

The clamps are Vise Grip brand 18 SP's with 10" jaws. I used them alot in the body shop.

The next time I am going to leave the root rib completely loose until I have the wing tube and sleeve in place. Then I plan to slip the wing on the tube and fit the spars and leading and trailing edges to the fuselage before I slide the root rib into the wing.Then it's clamp and bolt the rib to the fuselage sides making sure that the guide pins are aligned properly, followed byglueing the rib to the spars and leading and trailing edges. That should get a fairly snug fit . And thanks for the heads up on the gap not being a problem in the first place. It is comforting to know that some gap is okay.

Richard,

I filled any visible imperfections before I glassed the fuselage. I used two coats of clear to lay on the glass, sandedwith 180 grit followed by two sprayed coats of clear. Now I will block the clear and if it sands out clean (no imperfections) I will paint without having to use primer. If there are imperfections after blocking, I will apply two coats of primer and then reblock everything. Remember the goal is to get as smooth and straight a surface as possible without too much weight build up. In this case "less is best". That is why I won't be using primer unless I absolutely need to.

Bill,

I apparently misunderstood the purpose of the primer. I thought it was to find the imperfections. And I suspect that my version of a "medium" coat was much heavier than your definition. I've now reduced the amount significantly on the remaining tail surfaces. It almost sounds as though I should have filled any visible problems and then applied the carbon veil, rather than doing the primer bit on bare balsa.

I finally found some PlastiKote lacquer. Unfortunately, it's white, which doesn't show up as well against the gray primer, and it's not made in yellow. (Since I did find a place that stocks the brand, I sent a message to PlastiKote asking if they have anything non-enamel in other colors.)

Cheers, Richard

PS: Being a bit tired of still playing with the tail surfaces, I've decided to take a break and start on the fuse.

Richard,

It has been my experience in life, that when I run into a seemingly impossible problem, if I just step away from it for a short time a solution comes to mind. I can't tell you how many times I have left a difficult problem at work only to come in the next dayand have a quick and easy solution. It's funny how things work that way. So by all means take a break and it will come to you. Good luck and happy building

Bill

Just a couple photos of fitting the canopy to the fuselage. The red sand paper on top of the fuselage is 180 grit that comes in a three inch wide roll with adhesive backing.

Just for giggles a comparison of my Top Flite 86" P-47 wing and my Simla sans paint and wing sheeting. And just in case you can't read the 47 wing weight, it comes out at 161.5 ozs.

Bill,

There is something just plain wrong about building two large planes simultaneously (and having the space in which to do it).
So right now, the P-47 wing weighs more than the unsheeted Simla?

I'm making good progress on the fuse and was getting ready to finish drilling the various holes in the firewall so I could epoxy in the formers. Which brings up a question: Did your kit contain the nose gear mount or is that something we pick up at our friendly local hobby store?

My new tactic with getting a flat, smooth surface, at least with the tail feathers, is to apply a bunch of filler and then scrape it away. Any that remains is filling a low spot. No doubt it's adding a bit of weight, but it does help diminish my frustration level and lets me carry on with the build.

I have to admit, the fit of the parts in the kit is nothing short of amazing. I figure any errors are almost certain to be caused by me.

Cheers,
Richard

Richard,

Currently I am house sitting for my son who is selling the house and has moved to West Palm Beach, Fl. So except for my room the whole house is virtually empty. As a matter fact, of the seven major rooms, I am using four to build and store my models(Five completed and two under construction). The opportunity presented itself so I decided to take full advantage of it.

According to UPS I should be receiving my wing sheeting on Thursday. Probably late in the day but what can one do but wait. I am really hoping that the sheeting comes in very light, as I can see my Simla approaching 10 lbs. already. I still have a lot of sanding to do on the wing including the wing tips, leading and trailing edges, etc. I was surprised to discover that the wing tip blocks came out at less than half their original weight just after roughing them out. I also have yet to finish sand the fuse and feathers, so a bit of a diet is in this Simla's future!

I believe the landing gear mount was in the kit as a two piece unit, however I opted for a one piece unit by Carl Goldberg.

What you are doing to your tail feathers will most likely work well. When I built my elevators they came out slightly concave, so I did just what you say you are doing. I spread one entire side of the elevators with filler and then sanded them to shape. They are true and flat now, and only picked up 0.1 oz.

PS- The P-47 should come in at a total of between 22 and 25 lbs. But that is what it should weigh according to the build manual. It is powered by an OSGT-55 gas engine,and has 11 servos, three battery sources, retracts,full cockpit, etc.

Bill,

Your elevators came out a bit concave? Mine, too, along with the rudder.

Having just spent another hour sanding the stab, I'm beginning to think the situation isn't as bleak as I had thought a couple days ago. It occured to me that a lot of the minor scratches and so on were going to be fixed when I apply the carbon veil and the urethane. I've now patched all the really visible dings. When that gets sanded down, I'll do one more *light* coat of primer and guide coat. After that's sanded smooth, I think I'll be able to call it good.

Then it will be time to separate the elevator from the stab and see how I want to set it up. I will go with the hidden control horn but will probably attach it to the joiner rather than the red bearing method. Unless I'm missing something. I have time to contemplate it some more.

The fin is in good shape; almost no patching needed.

I do need to order the nose gear mount asap. The firewall is putting a halt to the fuse construction. "For want of a nail, the shoe was lost ..."

I'm searching through boxes to try to find my Great Planes Slot Machine. It really is great for cutting hinge slots. (After a year in the new house, and despite what we thought was careful packing and labeling, we still can't find things. I am never moving again!)

I have a house Ive been trying to sell for the last 14 months. (Know anyone who wants to move to Colorado?) I'd do my building there, but it's an hour's drive.

Take care and I sincerely hope Irene isn't causing you any trouble.

Cheers,
Richard

Bill, et all:

I have been building for quite a while and I am currently building some 2 meter pattern planes. I have found a couple of sources for balsa. One is as already mentioned and that is : www.nationalbalsa.com and a second is: www.thebalsastore.com. The Balsa Store is in Memphis TN and Clay is very helpful. Both companies have what is commonly called contest grade balsa (that is the balsa weighs between 4 and 6 lbs per cubic foot). I have bought balsa from both and found them both great to deal with. On my planes that are to be glassed and painted I have used National Balsa's bargain balsa. The bargain balsa has some surface blemishes that are easily covered by the glass and paint and the price for the contest grade bargain balsa is about 50% to 60% of the regular contest grade balsa. On parts that are to be covered with film, I buy the more expensive contest grade unblemished balsa. Currently there is very little 4 to 5 lb balsa available but they may have contest grade balsa in the sizes you need. Just FYI, a sheet of 3/32x4x36 inches should have the following weights: 4 lb balsa sheet should weigh about 14 grams (1/2 oz), 5 lb balsa should weigh about 17-18 grams grams (between 1/2 and 3/4 oz per per sheet), a sheet of 6 lb balsa should weigh about 21 grams (3/4 oz per sheet). A sheet of 8 lb balsa weighs about 28 grams (1 oz per sheet). In order to sheet my current pattern planes (950 sq inches for the wings) is use about 34 sheets of 1/16x3x36" balsa so you can see if I use balsa that is 4 to 6 lb balsa ( average weight is about 10-12 grams per sheet) I can save about 5 ounces in the sheeting for the plane over using 8 lb balsa (14-17 grams per sheet). If I am building a new pattern plane I will and have ususally bought about 20% more sheets than I need and then go thru them and weigh each sheet. What I do on my planes is to weigh each sheet (in grams since it is more accurate for the light weights we are using) and take the lightest sheets and use them on the vertical and horizontal stabs. For example, I just finished a new pattern plane (foam core wings and tails). I sheeted the airplane with 1/16x3x36 sheet balsa. The balsa on the vertical and horizontal stabs weight averaged between 8 and 10 grams per sheet and the sheeting for the wings weighed between 10 to 14 grams per sheet. Some carbon fiber strips (.007" thick by 3/4" wide on the top and bottom of the wings) provided some additonal strength

I try to match all of the sheets total weight for each side of the wing (equalize the weight of the sheeting on each side of the wing before glueing) and then laterally balance the airplane after it is completed and the engine and all accessories have been installed.

Just my 2c

Ed

Ed,

Your post is very informative as well as helpful. Thanks. I admit that this isthe first time that weight has been such a concern for me, but thanks to all the posts on the subject I am learning a great deal. I was glad to hear that you are using glass and paint. Do you find that it adds significant weight to your completed aircraft? If you have any tips on the finishing process I for one would like to hear them.

Bill

Just curious why you don't put more of the heavier sheets on the wing opposite the side mounted engine, (assuming the engine is side mounted). It will reduce the amount of weight that needs to be put on the "light wing" to laterally balance. The "accessories" that I have on SPA-type planes are all centrally located, or in the case of the muffler, on the same side as the engine...meaning more need for lateral balancing.

Now if the wing is upright or inverted, I'd understand the even distribution.

Just curious

Duane

Duane,

I know that this might be difficult to determine, but roughly what would you recommend as a ball park weight differential from left to right wing? When I originally weighed the sheeting I was able to get from as little as 1.0 oz to about 5.0 ozs. differential. Should I set the Simla up for lateral balancing and then just try stacking the sheets from wing to wing until I get a neutral balance?

Bill

There seems to be a fine line between too much hardener in the filler, and maybe not enough. After 12 hours (in a cool basement), I've got some patches that are still slightly rubbery. I brought them upstairs this morning hoping the warmer temperatures would help.

If the filler stays rubbery, is there anything that can be done? It's definitely too hard to scrape off.

Yet another learning experience.

Cheers,
Richard

My SPA planes all fly on an OS .91 FS, and required about 1/2 to 3/4 ounce on the wingtip.

Now that I have a digital scale, (like yours), and have become aware of the importance of building light, I'm just trying to make use of it to distribute the weight where I want it. In your case with that 120 2-stroke engine, performance is not a concern, but I use my planes in SPA competition where that fixed engine increases the importance of light weight and best use of the wood.

I used to think that people who weighed each sheet of wood were fanatical, bordeing on "nuts". Then I came to like the King Altair for SPA and quickly realized that EVERY OUNCE MATTERS because you are limited in engine output, and that if your competition has a lighter plane on the same engine as you, he is going to have a vertical advantage. I know that performance in wind might aid a larger or heavier plane in some cases, but what I just stated is a general rule of thumb.

This wood is going to be part of the weight of the ship anyway, so why not distribute it in such a way in order to reduce the need for additional lateral balancing weight...at least some? It's not an "exact science"; there probably are other factors that enter in, but it seems logical to me that DISTRIBUTING THE WEIGHT properly is a factor in reducing total weight.

There is another reason I try to do this besides trying to get use out of the scale, and the fun of weighing balsa, (and it IS kind-of fun to see the difference in weights between identical-looking pieces of wood). I was told by pattern great Ron Chidgey that it matters WHERE the weight is distributed, and not just the balance. I'm told that these planes roll better if the weight is more toward the center, so when you put a chunk of lead on the wing tip, it adversely affects the rolling characteristics even though the plane is "laterally balanced". Admittedly, this is the "world of perfection" for the aerobatics elite trying to get the perfectly balanced and set-up plane, and it may not matter as much for less accomplished pilots...still why not do things in such a way as to give the best flying plane that you can have regardless?

If the weight, (that is going to be there anyway), is distributed so that the least amount of additional weight is needed, then we should probably try to do it. That's why it is better to shift the battery pack than simply add more weight...to reduce total weight to a minumum, and to distribute that weight the best possible way.

The first plane I did this on was the Simla, and I wound up actually having to add a SMALL amount of weight to the right wing, (the same side the engine leans toward). In the case of the Simla prototype, I put ALL of the heavier wood on the left side. I may not do that on my King Altair wing I'm currently building, (I just ordered the contst balsa yesterday), but I will put MORE of the heavier stuff on the left wing.

Just my take on all this...waiting for a reply from Ed to get his take.

Duane

This little chart might prove useful. I weigh all my balsa on a gram scale and anything with 6llbs density or less goes in a separate pile for use when weight is lightly to be critical - the back end of scale models (and Simlas) for instance. Of course grain type is important but that's another story.

Ray

Very cool Ray...Leave it up to you to provide such a thing:

So the weights are in Grams?

So let's see:

a 3/32"X4"X36" weighing 15GM would be super-light ...right?

Light would be 22 and Medium 30-37?

Duane

Spot on Duane. As was mentioned in post #286, using grams is more accurate for the light weights we are measuring. 6llb or less wood is very difficult to find these days, at least in this part of the world, so I only use it when I really have to and drill holes in everything else [sm=what_smile.gif]

Ray

National Balsa considers their "Aero-Lite" CONTEST BALSA (in two grades regular and "bargain"), to be 4-7 lbs/cu ft. I ordered some of both the best quality Aero-lite, and "bargain" Aero-lyte balsa, (which is supposed to be equally light, but has more "staining"), to see if the "bargain" is really as light as they claim. National claims the only real difference is the darkness, (staining).

They say the non-bargain (best quality), isn't necessarily more clear or have better grain or less imperfections, but I believe it probably does, as Ed mentioned earlier. National recommends the "bargain" Aero-lyte for models that will be covered and painted so the "staining" won't matter.

I have three upcoming models to sheet, (two are foam wings), and it will all be used. I'll let everyone know what I find from my order, and it will be interesting to compare notes with the rest of you. Where did you guys order your balsa from? We might as well have our own "critique" of the balsa companies.

Duane

Duane,

I got the bargain Aero-Lite from National Balsa. The individual weights of the 20 sheets are in Post #254. Shipping was prompt and the sheets well-packed. A few had some small edge dings that shouldn't be a bother. My only "complaint" is that they didn't have any 4-inch wide balsa in the Aero Lite category.

Cheers,
Richard

Ed,

Many thanks for the informative post.

I wish I had heard of the Balsa Store before I ordered 3-inch wide sheets from National Balsa. The Balsa Store lists 4-inch wide sheets. Not sure why a search of the web didn't come up with that store for me.

Cheers,
Richard

I got a box of contest grade from The Balsa Store and it's really nice wood. I'll be back there for more!

Andy

Duane:
Regarding the weight distribution on the sheeting for the right and left wing (post 288) , in the current 2 meter planes the engines are all inverted and the muffler (4cycle) or tuned pipe (2 cycle) are all on the center line so there is no need to worry about having the heavier sheeting on the left wing (opposite the muffler). Same goes for all of the 2 meter electric (or probably any electric for that matter) planes have all of the weight on the fuse centerline. However, on the SPA type of planes where you have a large muffler on the right side of the plane (assuming the engine is mounteed upright) then it would probably make sense to add some number of the heavier sheets on the left wing.

With regards to the weight of the plane I will offer this. When I decided I was going to compete at the Nats this year and all of the planes were to be weighed to ensure they met the 11lb weight limit (if you are over the weight limit, you are disqualified), I knew I had to build a new plane ( built a Black Magic VF3 with a YS 170 4 cycle) since my two current planes were over the weight limit. I used all of the lightest balsa and when I put the plane on the scales I was under the weight limit by 27 grams (less than one ounce) so the attention to the weight of the balsa was essential. Incidentally, I completed the plane from start to first flight in five weeks of flat out building and I had eight flights on the plane before leaving for the NAts.

Richard:
While both National Balsa and the Balsa Store list various sheets of balsa it is important to ensure that they have them in stock. For example, if you visit the balsa store website, and you look at 4" wide balsa sheets ( the lite 4-6# sheets) you will see that to the right of the description there is an oval that says "notify me". This indicates that they do not have any of the wood in stock. However, if you send Clay an e-mail asking what he has available in 4" wide and or 48" long sheets, he will reply and the best you will probably get at this time is 6 - 6.5 lb sheets (which are certainly a lot better than the 8# stuff).

Bill:
In my opinion (and based on my experience) glassing and painting a plane will add more weight than covering an entire model in "film". I can cover planes in film but I have always been a galss and paint guy (that is probably why my pattern plane mentioned above barely made weight). Additionally, since the canopy, chin cowl and the belly pan on the Black Magic were fiberglass, I decided to glass and paint the entire plane. If you want some tips on glassing and painting there are many threads on RCu however, if you go to the pattern thread and do a search on Black Magic VF3 build thread, Mike Hester, Dean Funk and a number of others offer very helpful info on glassing and finishing. Additionally, if you go to: www.nsrca.us and select forums there are threads on building and finishing. These methods apply to all models regardless of whether they are pattern planes or not. As mentioned earlier various weights of balsa all have their applications and areas of use. When I am making fuse sides (these fuselages are about 74" long so I have to splice the sides), I will put the heavier wood of the sides at the front of the fuse and the lighter wood on the aft section of the fuse. Just as an aside, some number of years ago I used to hang around a vinatge aviation museum who built, rebuilt or repaired pre 1930 aircraft. I had the opportunity to be around when they were rebuilding a fuse for a CUrtiss Jenny (JN4). Many of the fuse braces, diagonals, etc. were reusable (they dated back to 1917 and were stampled with the date of manufacture) but the top and bottom longerons (total of four) needed to be replaced. I was surprised to find that the top and bottom longerons from the back of the aft cockpit to the front of the plane were 2" square ash and the top and bottom longerons from the aft cockpit to the tail section were 2" square spruce that was heavily milled out. All of this was to keep the weight out of the tail of the plane.

One more thing. Earlier in the thread I saw some discussion of use of carbon veil. I have used the veil between the foam wing and the 1/16 balsa sheeting but have not used it for any other application. I couldn't find it but I think that there was also some discussion about the application media (PPG urethane I think) was not hardening. I have tried many different types of media to apply glass cloth to airplanes and after evaluating different brands of stuff, I have settled (been using it for the past 10 years) on System 3 brands (www.systemthree.com) epoxy. If you go to their website you will see different types of epoxies. They have the run of the mill epoxy ( they call this epoxy resin) which many use to glue things together, they have their structural epoxy (called T-88) and then they have an epoxy called Clear Coat. I use the T-88 for glueing firewalls and other pieces that are very structural in nature in the plane. I use the general epoxy for stuff like glueing the wing tubes into the fuse and other items that do not have as much stress applied on them. I use the Clear Coat to apply my glass cloth. The Clear coat is very light (thin) viscosity (something like the viscosity of Aero Gloss clear dope). If flows very well. If you are going to glass an airplane the first thing to do is to try to seal the wood so that little of the epoxy is soaked up by the wood. What I (and others) do is to put two or three coats of Balsatire or clear dope on the wood (sanding between coats). In my last plane, three coats of Balsa rite to the fuse (the fuse has a total area of about 800 square inches (this is total for both sides of the fuse) I added about 18 grams (about 2/3 ounce)) to the weight of the entire fuse. Once this is done, I then lay the cloth down, apply the clear coat expoy. Once the cloth is wettted out completely, I take an old credit card (need to have rounded corners and very smooth edges) and squegee most of the epoxy off. When you do this, you are looking to have the cloth all have the same color. Any light areas will be a lighter color than the cloth that is wetted out. Put the expoy where it is needed to wet the cloth out. I typically use very little epoxy to wet the cloth out. Although I dont recall the exact amounts, I believe that for the wings for my latest pattern plane I mixed about 28 grams of epoxy. I used this to cover the top (for example) of one wing panel (approximately 475 square inches). ONce the cloth was wetted out, I squegged more than half of the epoxy off. The current target wieght for a 475 square inch wing panel (sheeted, with wing tube sleeve, glassed, painted and with servo and control horns installed is about 14 ounces .

If you are looking for a source for very good glass cloth, try: www.thayercraft.com. They sell good quality glass cloth for very good prices. I recently ordered 25 yards of 1/2 oz cloth that is 22" wide and I got it for $27 (shipped). I also ordered 50 yards of 3/4 ounce cloth that is 44" wide for about $65 (shipped). The current trend on glassing pattern planes is to use the 3/4 cloth. It seems to be a little tighter weave than the 1/2 ounce and consequently it seems to absorb less epoxy.

Just my 2 cents.

Ed

Ed,

Yet another very informative post. Many thanks.

I'm the one planning on using the carbon veil instead of glass. I read about its use on, I believe, a CL plane, and again more recently where it was described as being light and offering a bit more ding prevention. I've got some .3 oz. that should be arriving today from ACP.

For sheeting foam cores and applying glass, I've been happily using West Systems products. As you advise, wet out the cloth and then squeegee like the dickens.

This time, just to be different, I plan to try Bill's 2-part urethane method. Thanks to you mentioning the possible problem of the PPG (not the brand I bought) urethane not hardening, I will do a test. Besides, I need to find out if Ultracote will work over the carbon veil and urethane. Since my field is at 7,000 feet, I want to use the Ultracote to save some weight. If it doesn't work over the veil, I'll find someone who knows how to paint. I've never done it and don't have any equipment.

Cheers,
Richard