ProfLooney

So now the tail feathers are all done where to next. well it will take a few hours to redo but I will do the fuse section I had before then look into doing the rear section.

so for now we are done with the tail feathers and they are looking really good and match all our reference material perfectly. I can at this point if I want make all my parts for them and have them finished and ready to go but I want to get at least the fuse and center wing section finished because then I can make my framing all come together.

Ok since the tail is finished it is time I updated the E-drawing so you can use the link on the first page and download the drawing which is the up to date one.

as a side note to save going back each time you can bookmark that link so all you have to do is click on it and it will download the updates for you.

ProfLooney

well I took a road trip to champagne and I talked to avenger owner and he said he wont be able to be there but that I can go down to his hanger anyways and climb all over the plane taking pics and measurements.

thats pretty cool built up a nice repoir with him and now anytime I want to go down whether he there or not I can go and look at what I need

and I got some measurements etc of the wing fold as the wings are kept folded when in the hangar

Here is link to you tube for the plane I will be visiting dunno how to embed here so you will just have to go there and look http://www.youtube.com/watch?v=vFwPjZb4ZVA#t=206

ProfLooney

does anyone have a photo of the nomenclature stenciled on the 3.5" rockets?

I havent been able to find them

ProfLooney

Ok It took a bit but I have the fuse lofted to where it was before now it will take a while to get the rear just right that is why i put it off last time.

I will work some on it tonight then have to take the next couple days and get back to my day job on the b-24. hopefully by this weekend will get the tail end of fuse finished and the wings done where we can start designing the framing of this thing.

the e-drawing is updated and uploaded

ProfLooney

I have a few mins while waiting to hear back from the movie producers so I messed around with the stab framing.

In the first Photo that is how it looks all assembled and with sheeting. it weighs .82 lbs or 9.84 troy oz. I have a convert prog and it shows troy weight and something called AVDP weight for lbs and oz. since i dont know what the advp is I went troy. the stab is roughly 53 inches long and 9 inches wide.

ProfLooney

Here it is without the sheeting. I still need to add lightening and a couple 1/8 sq hardwood stringers to the top and bottom just to help support the sheeting.

ProfLooney

Now here I show a closeup of some items I do differently than Most other people and will explain in next post

ProfLooney

ok when I design like i said earlier in this thread I use as little balsa as possible.

A lot of people like using a big hunk of balsa for the L.E. there are 2 things wrong with that way that I see.

1. You are gluing a big bulky peice of balsa onto a small narrow end of a rib. this means there is a small gluing area and thus a weak point

2. it is a pain to try and shave and sand it to shape.

3. it is very prone to hangar rash and little dings if you run into something at the field.


Here is how I do it and the reasons.

First I make a core out of lite ply. the one here is 3/4" wide. 3/8 inch to notch into rib, and 3/8 for the LE.

on the rib I usually notch it abt 1/8 inch notch and that leave 1/4" to run along side of rib.

The core done this way does several things.

1: it gives a ledge to glue the balsa LE onto along with the edges of the ribs. this makes for a strong joint plus almost no flex.

2: it makes the LE pretty much ding proof unless you really hit hard.

3: with the core notched and along the side of the rib it helps with alignment during framing and gives the rib some strength because there are more gluing surfaces used.

4: the overall weight of the LE is usually slightly lighter or the same weight as a balsa LE because you are able to make a smaller LE and sheet more than a large hunk of balsa.

Next I add my sheeting before adding my balsa. This way I have the core as a little ledge to slide the sander on and I can sand down the sheeting overhang and get a really nice tight joint.

on top and bottom of the core I add a small balsa strip on the top and bottom and sand to shape.

the finished product you can see in the above pic.

Now a lot of times I will not trim off a few ribs and fill the balsa in between them and that way can use the ribs as a guide. I will show that later when I have more time.

ProfLooney

Next in the bottom pic is the TE.

I always use lite ply here too. no need for a huge chunk of balsa a piece of ply is stronger and weigh abt the same.

Since the sheeting overlaps slightly the elevators I like to notch the back of my ribs and lower the top and bottom of my TE by 1/16th inch so I can inset a piece of 1/16th ply for strength.

Alternate method you see a lot of people do is add G-10 type material on top. If you do it this way you need to sand some of the sheeting down or laminate the g-10 on top of some sheeting. when doing it that way its a little more of a pain than just notching a rib PLUS there is a seam where you join the G10 part and the sheeting. Plus you need to make your cuts just right so it is a nice clean joint not needing fillers.

By me putting it on the bottom I can then sheet all the way to the end in 1 piece without needing to worry abt joints or matching etc.

Now what difference other than ease does it make where you put it on top or bottom?

think about it for a minute put it on top you have strength on 1 side only THE TOP

Do it my way you have strength on the bottom PLUS strength on the top as we all glass our planes. so instead of weak balsa on bottom we have ply on bottom for strength and glass on top for strength thus making that lip almost accidental ding proof.

Like I said at the start these are my ways of doing it and other than with my initial lofting reasons my method may not be the same as everyone else s. But I have found out over the years they work and my planes can usually come in a lot lighter weight than others.

for example my 1/3 scale WWI planes built by the UK Dawn Patrol Show Team come in abt 32 lbs where the same planes built over here from other designers come in between 38 and 42 lbs.

its not a ton of weight but as the size and type of plane change it can be a big difference.

OK that's it for now we will leave open for others to chime in on their methods.

Oh and BTW all my stab ribs have 1/2 inch tall tabs on them than notch into the TE adding more strength there as usually big balsa TE aren't notched but butt glued like the balsa LE are

ProfLooney

I always use the original airfoil. in this case it is Root: NACA 23015 Tip: NACA 23009

for tail feathers the most commonly used airfoils are the NACA 0009 or NACA 0010

But since the Avenger had a fatter one I went with somewhere in the NACA 0020 Range


you can use your 3 views if they are good accurate ones like mine are to get the thickness but all they usually are is a straight symmetrical airfoil


One thing guys I forgot to mention and that is wood sizes.

We often use lite ply and I only use AC ply for a firewall or landing gear mounting everything else is lite ply. All Lite ply is metric so when you make notches or draw your ribs you need to drop .010 from the dimension.

We know 1/8th ply is .125 and 1/4 ply is .25, but when you draw it up you need to draw them at .115 and .24 so that you get a nice snug fit.

when you are drawing or notching balsa wood you use the actual dimension but ply you go narrower due to its being actually metric.



you can also use this site to look up airfoils it is pretty complete http://m-selig.ae.illinois.edu/ads/a.../aircraft.html

ProfLooney

Well I updated the E-drawing and got the stab all framed up to the final framing.

ProfLooney

I have to drill a hole in the Trailing edge yet but waiting. the far inboard notch from what I understand is where the pull pull cables attached to the Elevator.

ProfLooney

Well I got the LE of the elev shaped then I had to make sure I had all the correct clearances.

It is no good to design something and find out something doesn't fit. that is one bonus in designing in 3D and that is if it fits in 3D you know it will fit when built and so there is no need to prototype for assy just for flying as you already know it will go together nicely.

so here i can peek in the overlap of the stab to see if I have enough clearance and I can also do section views all the way along the elev to make sure there are no issues at any point along the LE.

I haven't totally figured it out yet but solidworks also has a feature that looks for interferences it doesn't show well as the stab and the elev are angled on the LE but I like to keep abt a 1/8th in gap between the 2 surfaces so once covered with the fabric it will still clear

ProfLooney

Ok I now have the ribs for the elevators made and the outer elevator caps which are notched so that they go into exact place nicely.

I will now leave the rounded shapes on the end pieces, add a couple short pieces for the notch area and possibly draw in the tubes for the hinge guides and cut the holes in the outer shaped pieces.

ProfLooney

and here it looks with the stab

ProfLooney

Here it is after I chopped off the rib ends

ProfLooney

Ok here is with the LE and you can see the weight and the pink arrows in the part show the CG. now for now I wont be adding the trim tab but thats basically how most designers including me at times do their elevators they use a 16th ply core and balsa slab LE. For this plane I will be sheeting the LE due to the Metal on the LE of the original. This will be the first time I try it this way but I am sure it will be fairly easy to sheet the LE due to the big airfoil sections and create a fairly accurate representation of the original you can see here it is only .24 lbs or 3.84 oz. so double that our total weight for the stab and both elevators comes to 14.88 oz so it is fairly light for the TE which means tons less weight going to be nose of this thing. by using solidworks once you are all finished you can make a steel box in the nose the weight of your engine and from there tweak things until you just need to add a few oz of weight to balance out the plane.

ProfLooney

ok guys I tried to do the sheeting method of the LE but by the time I was to add little walls etc for the notches there wouldnt be any savings in weight and would add more to the time. So I will be returning the elevator back to the original way with a solid balsa LE

ProfLooney

Had a few mins to finish off the elevators at least for now. may have to come back to them later but the basics are there for now

ProfLooney

I hid the ply cores in last pics so everything shows up better. since this is cad it would take hours to set up and angle the ply TE to a sharp end like is done when you sand so it wouldn't show the little balsa that you see surrounding the elev. That will represent the metal sheeting they use for reinforcement. also the trim tab I left off for now.

I find never work on an area more than 2 or 3 days at a time as you will develop tunnel vision and miss something or make something in the wrong place. so best to have fresh eyes on it later. So I like to get all the basic framing up and when everything else is made start from the beginning and go around finalizing the design.

so basically here for the elevators I made a ply core and later will add lightening holes to it.

I slotted the core and the ribs so they slide together ( will post pics after this)

Added a solid Balsa LE and balsa strips around the elev following the outlines for the Metal sheeting on the full scale.

made ply sides rather than balsa hunks and notched them to fit right into the ply core.

ProfLooney

ProfLooney

And that is how I like to design my Stab and Elevators so they are light weight and uses as little balsa as possible. for me with no hobby shops in my area it is beneficial for me to try and use as little balsa as possible because it is all mail order for me and hate to stop because I need 1 little piece of balsa with the ply I always have spare ply hanging around that is left over from the parts sheet.

ProfLooney

Ok guys I started the rear section of the fuse and lucky for me the firs time came out perfect that being said I am not out of the woods yet I still need to work all the way to the rear and because of the huge fareing by the stab and fin you cant really get an accurate fuse line so am using the one on my ref and hoping it is as accurate as the rest is.

I used my curvature tool and then used the zebra stripes and it looks great im so happy finally after years trying to get the fuse for this plane to work properly my skills finally let me get it right.

ProfLooney

Well so far everything looks good I still need to double check shapes to be sure I have the correct ones but looks good so far. I have updated the e-drawings also

ProfLooney

Here is the fin in place but until I actually go see the plane wed i'm just throwing a guess in