Ashhhhh

Thats sweet mate, looks really good!
How much does the gear weigh?

apwachholz

Ashhhhh -

I don't have a scale so I can't speak to specifics, however, the wheels are 1 3/4" Great Planes rubber treaded tires that run .48oz and/or 15 grams. The actual mechanical retracts are a non-factor for weight due to eliminating the steel rods. But on the high end, I'd just say a total weight of 17-19 grams was added (balsa, glue, screws included). Then add 0.66oz and/or 19 grams for the Hitech HS-82MG micro metal gear servo and you come up with a whopping 38 grams of additional weight.

Am I concerned about all the additional weight? Not really. Especially after having read and spec'd out the weight of Joshburns7 Dauntless gear and taking into consideration his flying experience (minus the unfortunate crash), I'm not concerned that the additional weight will effect it's flight characteristics. Will I be able to do Cuban 8's or an Immelmann turn? No, but that's not what a Dauntless was built to do

Plus with the help of my girlfriend (who's a pilot / aviation R&D'er) we did a "dirty" wing load test: We placed all my gear in a pile on top of the fuse, wing attached, and picked it up by the wing tips - and nothing happened. The SBD-3 will take the weight no problems. So now I'm fairly confident, that any weight/wing loading issues have expired.

apwachholz

[sm=thumbs_up.gif]It's all in the details

As I move forward with the fuselage build of the SBD-3 Dauntless, I needed to revisit the ailerons to finalize the installation; primarily the physical connection of the aileron rods to the servo. It seemed straight forward right up until execution. And this is where I ran into problems. The location of the servo to control the ailerons didn't allow enough push/pull with the rods to give adequate movement of the ailerons themselves. I was getting less than 1/8 inch movement up and down which was obviously not good! The end result was that I had to re-install the servo location by pushing it forward towards the front of the wing by about an inch.

Now I have 1/2 inch of deflection up and down for the ailerons. Perfect. Oh, and how did I connect the rods to the servo? Since the ends of my torque rods were not threaded, I couldn't simply 'screw' on some hardware. Instead I used 4 pre-drilled homemade plastic "stoppers" and 2 DuBro Aileron horns.

1) Slide one plastic stopper down the rod
2) Add a light dab of CA glue to the stopper
3) Slide the aileron horn on
4) Slide the next stopper onto the rod and dab glue

Works out wonderfully...

Till next post everyone. Cheers!

Mr Cox

Nice build, I would just like to add a few comments (after all, that's why it is a build thread isn't it);

CA and metal is not usually a good combination, I would give those joints a good twist to check.

I would also recommend to get a good scale, weight makes all the difference between barely flying and flying well in small planes. You might be surpriced how much several tiny things can all add to the total weight. That static wingloading test is something I have never heard of before...

buzzard bait

The issue is not whether the wings are strong enough to carry the weight, it's how much speed you will need to keep the plane in the air. High wing loading means higher take-off speeds, more likely tip stalls, and faster landings with more impact. It also tends to mean less difference between cruise speed and stall speed, and touchier controls for a given deflection. In general, high wing loadings make a plane harder to fly for less experienced pilots.

The 1/2 inch aileron deflection would probably be OK on a very light park flier type, but you might need to reduce it to keep yours controllable. Maybe others will have a better idea. I have vivid memories of a club member who built a somewhat heavy TF Spitfire with a large engine. He used the deflections in the kit instructions and it was way too sensitive to control. Not pretty. The deflections were 1/4 inch, by the way.

Not trying to dampen your enthusiasm - just alerting you to some issues.

Jim

apwachholz

Understood Jim. And I'm taking all the input on this particular thread and mulling it over while I move forward. I do agree with you and Mr Cox that weight plays an issue when dealing with smaller models such as this. However, it's not that the model won't fly - it's that its flying characteristics will be different from what I'm used to; and I'm prepared to deal with that. In regards to the aileron deflection, I don't plan on using the full 1/2 inch - that would result in some very unfortunate events. I just needed to ensure that I had enough movement in case i needed to add more then what i was getting total (the 1/8 inch).

Thank you for the info Jim, I appreciate it very much.

Andrew

Do you have a target AUW for the plane and an estimated wing area?

While it's true for all planes, models of this size will fly or die based on wing loading. As Jim pointed out, high wing loadings can turn a plane into an absolute bear to fly and leave you with a bad case of knee knocking.

andrew

jeffie8696

What is a little higher stall speed when you have an expert pilot?
I Love the heck outa this plane.

apwachholz

Andrew -

The answer to both the AUW and the estimated wing area is zero. I haven't given it much thought, as my primary goal has been to keep the weight as minimized as possible. But as for spec'ing out weight and wing load, I've left that decision to the makers of Guillows and have instead beefed up the wing with sheeting to help with all the additional weight that I'm adding during construction.

jeffie8696

how about functional dive brakes?

proptop

My Feedback: (8)

I was wondering if anyone else noticed the part about not having a scale or not giving wing loading much thought...

Here's to ya apwachholz [sm=thumbs_up.gif] [8D]
You're doing a nice job on the build....
You'll find out soon enough if it's got a high wing loading...

apwachholz

Proptop - thanks!

Jim / Andrew -

I'm going to admit that I am very new compared to most when it comes to the world of radio control. Specifically when it comes to building from kits or from scratch, my experience is extremely limited and my knowledge of structure is more "cover-your-eyes-and-point" then it is logic and math. However, one of the items that I've noticed is paramount among many builders is concern over wing load and/or assessing its value to the build.

I understand that this is a no brainer when it comes to the aviation industry, but I'm unsure exactly how wing load is brought directly from real world aviation into rc and applied. The concepts everyone talks about and the formulas are correct, however, are we necessarily applying the 'idea' of wing loading correctly? And for that matter, is applying it in such strict mathematical terms necessary?

What I'm trying to say as one example is this: Since we over power our aircraft and in a way make the aircraft do things they were not meant to do (i.e. taking a P-61 Black Widow and performing sustained inverted flight and Immelmann turns) at what point does practical math and concepts in and for aviation applied to rc, become obsolete or irrelevant?

==> EDIT <==
If you would care to follow up more on this, we can start a thread in the Aerodynamics section. I think it would be a great topic to discuss more.

Andrew

apwachholz

I know that all the comments about wing loading may seem overly critical at times, but it really is a concern by the posters that you could have a finished model that is exceedingly difficult to fly. You're obviously working hard on the build and the SBD looks great. We just want to make sure that it looks great after maiden.

Guillow's kits have the reputation for being "heavy" for models in that size range - essentially, they have a high wing loading. Jim discussed the potential problems associated with high loading. We would commonly say that your CUB "flies on the wing" which means that the CUB's wing generates enough lift at partial throttle to stay in the air. Stalls are probably gentle, with the CUB mushing or just dropping the nose slightly.

Many planes with high wing loading are simply dragged thru the air using brute power. You're not going to get that power/weight ratio with most 1/2A engines and the wing cannot support the weight of the aircraft unless it is flying very fast. The stalls, whether slow speed or high speed, are usually vicious with one wing dropping and the plane going into a spin, many times unrecoverable.

We calculate wing loading in ounces/square foot which is why several have inquired about weight and wingarea. If it is too high, you may not be able to get the plane off the ground and if hand launched, the plane may snaproll before it gets up to a flying speed needed to remain airborne.

Wing loading actually becomes more critical with small models than full sized aircraft because we don't fly as fast. Generated lift is not linearly proportional to speed, but rather equal to velocity squared.

Don't be put off by the wing loading comments; we all want you to have a successful experience.

andrew

proptop

My Feedback: (8)

Very well put Andrew...we definitely want you to have success...and you are doing a very good job of building, however, I feel as though you are "over building" somewhat. (one clue is, you don't really need 2, 8-32 steel bolts to hold the wing on a 1/2A size airplane )
Experience is the best teacher...(think I heard that somewhere before?)
Don't let any potentially negative comments deter you...they are not really negative, just experience talking...

You strike me as someone who does what he wants, and "lives and learns" as do many of us here...

That thread of yours in the Aerodynamics forum tells me/us something too...that you want to learn, and that's always good![8D]

apwachholz

Thanks for the feedback gents. And no, I'm not discouraged at all and I do have a couple of thoughts that I'll jot down later. However, in the meantime I would encourage you to take a peek at the following link to YouTube:

[link=http://www.youtube.com/watch?v=pe9PVaFGl3o]Boeing 777 Wing Load Test[/link]

This is a real world parallel regarding my "dirty wing load test" in a previous post of mine.

Andrew

Ah!! This may well be where we are having a disconnect.

Even though the name is the same, I suspect most of your comments have been directed toward structural wing loading. We have been referring to aerodynamic wing loading. Structurally, your plane is more than strong enough - like the Boeing. Aerodynamically, we have been worrying about it being too heavy to fly well.

I can certainly see how the two terms can be confusing since we almost always build with aerodynamic loading in mind. Structurally, many of our planes are over-engineered. A common phrase you will see in this forum is, "Build to fly, not to crash", meaning simply that you can't add enough beef to survive a bad crash or paraphrasing, lighter is better.

Regards,

andrew

Dan Vincent

Back in the mid-70's I bought a set of plans from Wing Mfg. for a 42" wingspan Douglas Dauntless. I also bought the canopy and cowl.

The plans say it should weigh about 2 lbs and they recommended an .09 or .15. Today they would recommed a larger engine.

If anyone is interested I still have this stuff.

buzzard bait

Yes, Andrew's saying what I was trying to get at - there should not be any structural issue for the wing, but there is likely to be an aerodynamic one.

Wing loading can be a little misleading. Small planes need lighter wing loadings than larger ones. Basically it comes down to the fact that you can scale down the proportions, but the air molecules don't follow suit. A full scale plane might be very light at 25 lbs/sq ft while a 1/6 scale model might fly similarly at 15 OUNCES/sq ft. Go down to 1/12 scale and you would be shooting for 8 ozs/sq ft.

It's true that our planes do not fly very scale like. But how far off is acceptable? There are two issues: how realistic is it in the air, and how does it behave in the air? Even if you don't care about the first, you do have to worry about the second. Also, I find that while I don't need scale speed to enjoy a scale plane, there is a limit. Scale speeds of Mach 2 may not look very satisfying with some types. But that is a personal matter.

Your plane is very small by RC standards, and our collective experience is warning you that it could spell trouble without careful attention to weight. But like Proptop and the others, I admire your 'can do' attitude toward the project, and you will learn a great deal from it.

By the way, I think you will find that the aluminum tubing will not hold up to landings. It looks great, but music wire has earned its esteem from modelers by its flexibility and strength.

Have at it! Jim

apwachholz

Valid points all and I do not intend to dispute anything regarding the concerns with wing load and/or weight of a model this size. Nor am I going to dispute what others have experienced when building the same thing. However, let's look at the inevitable truth regarding the building of my SBD-3 Dauntless: Its build is going "outside the realm" of what a majority would consider plausible. And am I crazy for doing it? You bet

Tell you what, let's curb this particular conversation till I've gotten it up in the air and done some flying. Then we'll let the debriefing begin I'm game if you are, and I'm completely willing to admit my mistakes where they lie. And Jim, I'll argue your point on the aluminum tubing. I believe I have indeed developed a gear that will hold true. But we'll let the gear tell its story once all is said and done.

Thanks guys for the feedback, seriously. And hang tight for spring when the rubber meets the road and truths will be told.

And now... [sm=thumbs_up.gif]On with the build.

apwachholz

[sm=thumbs_up.gif]I Am Iron Man!

Well, not really... but it's fun to think so while your working. And so begins the next post of this build with the construction of internal linkage structure(s) for the rudder and elevator of the SBD-3 Dauntless. It took a while to 'think out' the initial wire work, but now that is past I've started to assemble the parts. Essentially what I'm doing is chopping off the tail section of the Guillows model and creating a removable tail (heated & vacuumed plastic) section that within, I can assemble all of the linkages for the elevator and rudder.

As a bonus round (and quite by accident) through this very same approach I'm also able to create a steerable tail-wheel simply by extending the rudder wire down and out the bottom. I'll detail that one later. But, for now, here are a few pics of the initial rudder and elevator internal mechanics with the rudder being covered and 80% complete. There will be more to come as I finalize, but enjoy the pics as there will be more to come.

Till next post, Cheers!

alcarafa

ANDREW I AGREE TOTALLY WITH YOUR COMMENT ABOUT GUILLOWS HEAVY ENDING PLANES AND HIGH WING LOAD, I ONCE BUILD A ME-109 HAD 27" WIGSPAN, 5 1/2 " ROOT RIB AND 2 3/4 " TIP RIB, FUSE LENGHT 21 3/4 " POWERED WITH SPEED 400 ELECTRIC ENGINE, LET ME TELL YOU THE PLANE NEVER FLEW, STALL WAS GUARANTEED AND SPIN WHERE UNRECOVERAL.

THE PLANE ENDED STATIC DISPLAY [:'(] AFTER MANY CRASHES.

REGARDS.
RAFA

apwachholz

[sm=thumbs_up.gif]Paint, Plastic, and Patience
With all wing linkages complete, it was time to work on other wing details that, ironically, will not be fully realized until the projects completion. One of those details was the infamous 'swiss cheese' flaps that the SBD-3 Dauntless is known for.

Before completely sheeting the wing I needed to do some painting on the inside. Why, you ask? I'm not installing flaps in this model as I see no reason for them, however, I do want the scale appearance of the 'swiss cheese' flaps. When looking at the real aircraft you'll notice that the insides of the flaps are painted bright red. For me, this was a nice contrast in color as well as a great detail I wanted to incorporate. I decided to paint the inside of the wing maroon red (where the flaps would normally reside) then finished sheeting the wing. Later on I'll Dremel out holes for the 'swiss cheese' using a pattern sheet included in the kit to keep the holes lined up and spaced evenly. This will create faux flaps without having bland tan balsa wood showing through the holes.

In addition I added the plastic wing details included in the kit. I'm not exactly sure what they're called, but I know the real world use was to create and enhance better airflow over the wing(s) during a bombing dive/run. By precisely cutting only the sheeting of the wing and matching up the edges I was able to get detail added that will set it apart from the rest of my fleet.

Oh, the random pic of the aileron is a detail of how the control rod will "plug" into the aileron itself. This allows me to remove the aileron (if needed) by simply cutting off the CA hinges. It also gives strength to the internal connection being a metal on metal connection and not a metal to wood connection.

Of course, more details to come. Cheers Everyone!

Andrew

The plastic details are for leading edge slots. Slots may be either partial width located outboard on the wing or full length, many times found on STOL aircraft. The purpose is to increase boundary layer airflow over the top of the wing when the plane is flying at high angles of attack by allowing air to flow from the bottom side to the upper surface. Ultimately, they were designed to increase the stall speed.

It's looks like you're making good progress on the build - waiting for more pics.

andrew

apwachholz

[sm=confused.gif] Dauntless Build Where Are You?

Yes, it has been a while since I last posted updates to the build. As I'm sure we're all accustomed, things have a tendency to pop up from time to time in life and it takes us in a different direction for a while. I just wanted to let those who are following this build that while not much has progressed for the past month - the build is still on. Cheers to those who are standing by, I appreciate your patience.

TFF

I would say Guillows planes are heavy for rubber band power; very hard to do, but RC with the right equipment it should be fine. In the 70s if you built one with a two channel radio and an .049 it would weigh 25-30 oz. Heavy for now but great then. Now if it weighs more than 20 oz, most scream. The big thing is are you up to flying it? It will have to be flown like a pylon racer more than a Cub. Pretty neat though; I always like small planes.