RE: SIMLA BUILD THREAD
 

This particular control horn is better when produced in the shop, due tothe required angle of the dangle between the elevator arms and the control horn. Besides, a custom made part gives a sense of accomplishment.http://www.rcuniverse.com/forum/js/f...eeth_smile.gifAnd if you build a lot of planes you probably have everything you need lying around as left overs ie. no added cost, trips to the LHS, or ordering and then waiting for a delivery. Seriously, I spent more time thinking about this control horn mechanism than I did making it. But then that's just me.LOL BTW I made two,one 1/8" with the red bearings and one 5/32" with the blue bearings. Ultimately I went with the 5/32" because it just seemed stronger.

RE: SIMLA BUILD THREAD
 

billberry:

If you look at Ed's elevator horn for the "Unfinished" fuselage, (which is still pristeen), you can see it looks a lot like the one you made, except his is all metal, and his is soldered. Just be sure thet set screw doesn't slip, or you're "toast". Yes with a plane this size, I'd definitely go with the strongest you can make.

I referred to a CF pushrod in an ealier post...attached is a picture of that pushrod. The rod is drilled/tapped for a 4-40 threaded rod. Aluminum tubing on the ends keep the CF from splitting or chipping.

The servo is located on the plane's exterior, and the linkage is short and with no "play". I'm installing this into my King Altair prototype, (Altair #4), whose fin and rudder required some repair. BTWThe fin has been cut down some is a bit less tall...the top basically cuts across the words SPA 22. Picture later.

RE: SIMLA BUILD THREAD
 

FUSELAGE:

As you can see from the photos, I used Titebond to glue the thin ply doublers to the balsa sides. If you haven't gotten the message yet...DON'T DO THIS unless you have a complete set of encyclopedias to use to keep them pressed in place...then still don't take the risk. [8D] In all seriousness, my doublers weren't all that bad, but it took additional gluing, and it was irritating. Use a drier method.

The fuselage pieces fit together very precisely...it was a pleasure. :) The doublers automatically set the angle for downthrust and sidethrust. Be certain you glue the correct doubler on the correct side, (and for that matter, the inside of each fuselage side)...nothing like realizing too late that you have two "left feet". I added the bulkheads to the right side, and left room for triangular bracing for each bulkhead...it's what I do..I think it provides more strength.

There is nothing fancy or difficult in these steps. Personally I added pieces of extra bracing here and there as I saw fit. You may or may not want to do the same. Here are a few additional points you might want to think about:

1) Draw a centerline on each bulkhead to help insure that the fuselage is straight. Jeff provides holes on the fuselage sides to help with the alignment. I didn't personally use them.
2) One thing I DID do was to use the small wing dowels provided to make sure the doublers are accurately aligned, (see photo). I found this worked pretty well for me. There is nothing quite as aggravating as not having the wing dowels precisely fit the alignment holes later on.
3) I used cross braces across the fuselage top and bottom to provide some additional strength/ridgidity.
4) As Bill already stated, the best time to drill all your firewall holes is BEFORE it is installed.
5) Once you get the bulkheads in place on one side, build upside down on the flat top surface of the fuselage. The fuselage is joined at the tail, (and cross braces installed), after the primary bulkheads are all set up and dry to make sure nothing gets out of alignment.
6) When it came time to join the fuselage halves at the rear, it appeared to me the fuselage was a bit short when bent to join. I added an extra piece of balsa at the rear as the picture shows to get the proper length. This also provides a nice surface for the rudder hinges to anchor to. I may have the most "beefed-up" rear joint of any Simla in existance. ;)

Because I didn't cut out the elevators after building the stab, but instead built them up conventionally, you can see where I needed to add a small wedge of balsa at the rear of the stab cradle. I HAD to build my elevators separately because the stab ribs were too short in the prototype, but if you should choose to build your elevators separately, this is the procedure you'll follow to fill this area. It all works out the same in the end.

For you beginning builders...nothing to it...right? Just take your time and make sure everything is straight and aligned. More to come.

Duane

RE: SIMLA BUILD THREAD
 

Good Morning Duane!!!   I have been working on my fin and rudder this morning and I was wondering how much throw is needed on the rudder. Right now I'm at about 4 1/2" side to side at the widest point. Is that enough or does it need to be more?

RE: SIMLA BUILD THREAD
 

I'm getting this feeling you're a better builder than I am. I never measured.[8D]

There are two methods for the control surfaces I've used...one was employed by Vic Husak on his King Altair, the other seen on Ed Kazmirski's planes. Vic used a 45-degree bevel of the control surface so it comes to a point where the hinge is placed so you (at least theoretically), get a full 45 degrees in each direction. Ed in all his planes simply rounds the control surface uniformly so there is no real limit. When I build the King, I make the "bevel"...and when I build a Kazmirski plane, I round the surface...including the Simla. Builder's choice. I always try to get as much rudder throw as possible when building, then adjust throw to get the flying characteristics I want. I like a lot of throw for Stall Turns.

Duane

RE: SIMLA BUILD THREAD
 

Duane,

Speaking of the fin and rudder, I've sheeted the rudder and have cut the pieces for the fin sheeting.

Looking at your images (on page 3 here), it looks as though you shaped/rounded the leading edge of the fin and then sheeted it, also. Is that correct?

Thank you,
Richard

RE: SIMLA BUILD THREAD
 

Richard,

Sorry to intrude but...... according to the late, great Jim Kirkland, and who am I to disagree, any throw greater than 35 degrees each way turns the rudder into an airbrake. If it is not effective enough with this amount of throw then add more rudder area.

Ray

RE: SIMLA BUILD THREAD
 

Rewritten for clarity??
...That is correct. The entire fin is sheeted, then sanded. This is one of those occasions when "Sigment", or sandable glue should be used. To review the way I handled the fin, on page 3, (post #56), this is what I said about it, and why I felt it is one of the trickier parts of the build. If you look at Ed's fin, you can see not only the L.E. is shaped, but the "truss area" behind the L.E. piece is shaped somewhat to an airfoil shape, producing a relatively thin vertical fin for such a large plane:

To me, the fin, (and especially the rudder), is a little tricky becase at the base the finished, sheeted fin is 3/4" wide, and at the top, (tip), it is 1/2" or less depending on taste. You have to shape the fin from bottom to top, and curve it from front to back to give it a Kaz-like airfoil shape. Ed didn't build it as a 3/4" simple slab. You can see Ed's looks relatively slender at the top, and rounded/tapered at the leading edge.

Rather than just sheeting the structure, you may wish to shape the fin as described above, and taper the truss in the building process, because the sheeted structure can be sanded only so much. I am just describing what I did, (for better or worse). I wanted my fin truss pieces to support the sheeting...that's why I tapered each piece. Notice the oblique view...you can see the tapering. Once one side is shaped and sheeted, you can flip it over and shape the other side some before sheeting.

If you look at Kevin's fin compared to mine, I don't believe Kevin sanded it as much as I did...it's a matter of taste, and the "look" you are trying to get. If you look at the finished fin detail of my prototype, you can see where I actually sanded through the fin sheeting at one point, and had to add a little wedge of 1/32 ply. I wanted the fin with a nice airfoil shape. The widest point of the fin roughly corresponds to where the filler material is.

Duane

RE: SIMLA BUILD THREAD
 

Billberry,
I definitely dig the red bearings on your horn!
Chris...<br type="_moz"/>

RE: SIMLA BUILD THREAD
 

That's all probably true, but I'm looking for a strong rudder effect when I need it for the Stall Turn in particular. With today's modern proportional transmitters, Dual Rates and Expo...you can get whatever you want...whenever you want...but only if you have enough throw in the first place. I would not normally kick in full rudder while flying at speed.

I'm no expert, but I'm learning every day.

Duane

RE: SIMLA BUILD THREAD
 

Richard, If you want any kind of air foil to your fin and rudder, itis best to establish it before you sheet the the surfaces. What I did was to tack the rudder to the fin with 3small dots of medium CA on the fin trailing edge. Then I used a long block 12" X 3" to taper the assembly fore to aft,top to bottom. Again, marking a center line along the leading edge of the fin, over the top of the fin/rudder joint, and down the trailing edge of the rudder will help you accomplish symetrical airfoil sections on both sides of the assembly. After I had the airfoil I was looking for, I separated the fin and rudder, sheeted both sides of each of them, and rounded as necessary. Even with this technique, several areas of the fin sheeting became very thin. Oh well, weight saving!!!http://www.rcuniverse.com/forum/js/f...eeth_smile.gif

RE: SIMLA BUILD THREAD
 

.....Again, marking a center line along the leading edge of the fin, over the top of the fin/rudder joint, and down the trailing edge of the rudder will help you accomplish symetrical airfoil sections on both sides of the assembly......

Yes absolutely the drawing of a centerline on the leading edge and trailing edge is essential to make sure you're tapering the control surface evenly on both sides. As long as you can see that pencil line, you know you haven't over-sanded the surface. We will see the same thing on the wing when we go to sand the L.E., T.E. and control surfaces.

I use a sanding wheel attached to my Dremel scroll saw for shaping small parts, and a long board with sandpaper glued to it for larger surfaces. I even use my trusty orbital sander, (with a light touch) to sand larger surfaces. When you have those centerlines it makes all the difference. This is something I've been doing for so long that I didn't even think to mention it, but it's very important. Thanks "billberry" for your technique.

Duane

RE: SIMLA BUILD THREAD
 

The term "airfoil shape" is now being used. To me, this implies a leading edge that then widens before tapering back down, like the wing. I had been following the directions that came with the kit. Those directions do not mention an airfoil shape. Rather, they say to sand from the trailing edge of the rudder to the leading edge of the fin. What this produces is a flat surface that would appear as a wedge if viewed from the tip.

Do I need to restart the fin and rudder from scratch?

Thank you,
Richard

RE: SIMLA BUILD THREAD
 

...this implies a leading edge that then widens before tapering back down, like the wing.... YES THAT'S BASICALLY IT....IMO.

It's up to you. If you'd prefer a more "airfoil shape", no need to rebuild from scratch, but depending on what you are happy with, you may want to re-sheet the front section of the fin after sanding to make it thinner...Look over page 3 for the general fin shape, (remember mine is the original fin that was later changed, but it should look similar). To me, it should not look like a wedge from the top, and be wide and blunt from the front IMO, but as you can see from the pictures of Kevin's Simla, Kevin's fin is thicker up front so it's a matter of taste.

When you sand back from the L.E., you may go through the sheeting before you find the taper you want, but that's OK. Sand until you have the shape you want, ("airfoil" or not), then resheet the front of it if you have sanded through it. I have found that balsa filler helps a lot at times like these. You may also choose to simply round the L.E. if you'd rather not do all of this...it's up to you.

I don't have any really good pictures from the top...hope these help...if there are any remaining questions, feel free to send a PM.

Duane

RE: SIMLA BUILD THREAD
 

Duane, do you have a photo of the undressed bottom of you Simla?

RE: SIMLA BUILD THREAD
 

And who says a "build thread" can't be "edgy".;)

I will post the rest, (or most) of the remaining fuselage pictures tonight. In the meantime, look at the article which does have a few fuselage pictures..some of which are from the bottom. What are you looking for?

One more thing to keep in mind to avoid confusion about the fin. Looking at the plans, there is no indication about "shaping" or narrowing the truss behind the fin L.E. to give it more of a thinner, or "airfoil" shape. That being said, I wanted to do that in my model in order to more closely duplicate the way Ed's fin appears to me from the photos. To me, Ed's fin is quite tapered, and doesn't appear to be blunt and wide at the L.E. It's all a matter of taste because we must remember there WAS NO OFFICIAL PLAN. Everything we did depended on comparing our model to Ed's photos, and trying to get what each of us thinks is the most "true" look...compared to the photos. I shaped my fin more than the plan shows...Kevin, I believe, built more to plan as drawn.

RE: SIMLA BUILD THREAD
 

Duane, I tend to lean more toward your tastes when it comes to the shape of the Simla. That is why I am interested in how you shaped the bottom and why I asked for some photos of the bottom. So far there seems to be plenty of side images and upper images but not so with the bottom. Also, the line of the bottom has a "hitch" on my Simla at former F3. For some reasonit just does not transition smoothly fore to aft.

RE: SIMLA BUILD THREAD
 

The bulkheads themselves somewhat dictate how smooth the transition can be...all you can do is sand to the formers, (bulkheads), and round as much as possible.

You reminded me of something...one of the design characteristics I wanted Jeff to incorporate into the plan. Remember the wing covers the fuselage bottom at F3...we wanted a smooth transition from the point the fuselage emerges from under the wing, but it isn't important for the entire fuselage bottom to be curved. I asked Jeff to design the Simla fuselage so it could be set flat on a tabletop for charging purposes without having to be in a cradle. I got this idea from my Daddy Rabbit, (which has a similar mid-wing design, see photo, and the Daddy Rabbit looks fine, as does the Simla...you never notice it). In other words, a section of the fuselage under the wing should be flat...you can see it on the plans. That may be the "hitch" you are referring to. It is not supposed to be a smooth transition, and with the wing on, you will never see it.

There are two hatches...one from F1 to F2, and a second under the wing from F2 to F3. This second hatch is for access to the radio, linkages etc. I'll post more pictures tonight. In the meantime, I hope this helps.

Duane

RE: SIMLA BUILD THREAD
 

Thanks Duane, that certainly straightens out some confusion for me. I know I built the fuselage as directed and I could not figure out why the bottom did not flow smoothly from front to rear. A built in flat area makes sense as you suggested.

RE: SIMLA BUILD THREAD
 

REVISED:

Assorted pictures of the fuselage details. Some of these photos are Kevin's. We live 20 minutes apart, and got together a few times to compare notes, and work on "stuff". In the pictures of the fuselages together, Kevin's is on the right in the "upright" photo, and mine is one the right in the "inverted" picture, (it is truly remarkable what sanding does to transform the fuselage). Wait 'till you see the upcoming pictures before the top, side, and nose blocks are sanded!!

In the pictures of the engine compartment, Kevin and I both chose to build ours with the engine compartment open like Ed did. As mentioned earlier, the plan makes provision for either an OPEN or ENCLOSED cowl area. In the corners you will need to add pieces of filler balsa...even so, there are places where the balsa is pretty thin in the corners...especially if you go for a "sleek" look, (which I did). Hold the nose up to a bright light, and watch for this possibility if you want a sleeker look.

Admittedly, I did a great deal of final sanding, taking as much off as I could to give the leanest, sleekest look I could on my prototype, especially on the top and bottom nose blocks. You will notice in the balsa, (unfinished) side view up above that the plane has a decided "Taurus" look to it, and it needed to be more slender. After that early picture was taken and I studied the side view, I "sanded the heck" out of the nose blocks to try as much as possible to achieve this more "Simla" look.

In the final plan revision, small changes were made by Jeff to narrow the nose section, and give that more "slender/sleek" look to make it look more like the Simla, and less like a large Taurus.

About the open engine compartment, I had never done this before, and originally was against the concept of "letting it all hang out", but I really warmed to the idea as time went by. I really like it now, and hardly even think of it, it's quicker and easier to build, the engine and nose gear is easy to get to, and best of all...it's the way Ed did it.:D

More to come.

Duane

RE: SIMLA BUILD THREAD
 

Not to say anything...but if you use 'normal' (dubro type) hinges then you must use bevelled edges on the surfaces, if you use rounded edges then you must use sewn thread hinges. Rounded edges with normal hinges will really limit travel unless there is a big gap between the surfaces...and we don't want that, do we...
Evan.

RE: SIMLA BUILD THREAD
 

Well Evan, I hadn't noticed that, but I'll keep it in mind...maybe my "gaps" are larger than yours. [8D] Everyone...you have been warned.

Duane

RE: SIMLA BUILD THREAD
 

I would agree with pimmnz. I recently finished a Carl Goldberg Sr Falcon kit and was struck by the hinging method. The wing trailing edge and aileron leading edge were both to be round and use flexible hinges(we call them ca hinges today). It is obvious that geometrically there would need to be a gap sufficiently wide to allow control surface movement. So I made the wing trailing edge flat and the aileron leading edge tapered.

RE: SIMLA BUILD THREAD
 

I revised post #189, (actually #120) some.

Keep in mind...when building the PROTOTYPE kits, we were constantly checking our prototypes AGAINST ED'S PHOTOS, and noting any changes we thought should be made to the final plan, (and kit). Hopefully you will not need to sand quite as much as I did in an effort to get the more slender "Simla" look. The prototype's nose section had a decided "Taurus" look that was refined for the final plan.

Duane

RE: SIMLA BUILD THREAD
 

Duane, in post #124 you say you revised post #189. Now I'd have to say that's a pretty good trick! So far the only real problem that I have run into is with the bottom block between formers F2 and F3. In my particular case that block could have been an eighth of an inch wider. Ultimately, I added a sixteenth inch shim to both sides from the front to the rear of this block, which solved my gap problem.