codyhenning

My Feedback: (6)

For all of you who know what you are doing, i have a quick question. I am getting ready to build a debonair and was wondering what thickness of coroplast i should for the wing use since i will be powering this beast with a 40 LA. Would 2mm be better for weight or does it really matter??

RC-Captain

[sm=lol.gif] Do yourself a favor, use a bigger engine. Or plan on keeping the weight down to 5 pounds or less. .

codyhenning

My Feedback: (6)

Love to do that, but college students/athletes have no extra $$ for things like that. Im struggling to find enough money out of my own wallet for the components of the craft. Any other suggestions would be defintally appreciated.

DLSmith2

Cody,

One of the best flying SPAD wings you'll find is the RNAF (Red Neck Air Force) wing like on the DPS. It's 4mil on the bottom with the flutes running span wise, which lets you make your ailerons out of it and save weight, and using 2mil for the top of the wing with the flutes running chord wise. I've been flying a Deb for the last two years with that type wing with one spar and about two inches larger (chord wise). It was a smooth flying trainer, stable, and would float all the way down the runway. You won't go wrong with the RNAF wing and the Deb!

The 40LA, while not a power house, will pull the Deb around the sky, especially if you have the wing I described, which will lessen the wing loading and make it easier for the engine to do it's job.

Keep us posted on how the build goes and don't forget the pics!

Blue skies,

DL

bkdavy

My Feedback: (1)

To save as much weight as possible, you'll also want to swiss-cheese the fuse. Assuming you're using the american pipe, which is heavier than the canadian, you won't notice any significant weakening of the structure, but it will save a few ounces.

Go with the tail dragger configuration and save the weight and cost of the nose gear. A wire tail skid up through the elevator and attached to the rudder will work fine for ground handling.

I second the RNAF wing configuration (4 mil bottom, 2 mil top, single spar). If you're a beginner, use the same di-hedral as the regular Deb wing. If this is a second or third plane, skip the dihedral.

Assuming you haven't already purchased the engine, skip the LA 40 and go with the Thunder Tiger Pro 46. Its only $20 more than the OS 40 LA (Tower Hobbies), but more importantly has WAY more power. (skip a few beers and sell an extra pint of blood ) I fly a TT Pro 46 on my Debonair with a range of props (11x4 at 14000 rpm for aerial photography, 11x5 at 13000 rpm for tooling around having fun, 12x4 at 13000 rpm for short takeoffs and landings). With the 12x4 prop, I can go vertical off the grass runway after about 20 feet.

Think of the engine as an investment. You won't regret it.

Brad

codyhenning

My Feedback: (6)

Thanks for the suggestions boys, you are of much help to me and i appreciate it. Ill keep ya'll posted on the progress and pics.

RC-Captain

Right now as I type, I am getting ready to swiss cheese my fuse. Do you know if the fuse can be covered with monocote ? will it stick ? Thanks

DLSmith2

RC-FIEND,

One suggestion: find your CG and install your wing hold-down dowels. THEN pick out where you want the swiss cheese holes to go (don't ask me how I found this out... []

I covered the holes with packing tape, and it works well except for where I have a zip tie holding the battery, etc on.

Good luck and don't forget the pics.

Blue skies,

DL

RC-Captain

To late, I already cut the holes , but don't think it will make a difference. So here are some pics with the cheese holes and the fuse with engine mounted is 1.5 pounds. bath room scale.

doityourself

sweet thats some thick gutter pipe is it the stuff that is made in the usa? i have never seen it that thick. That looks cool, just loving those holes. oh ya what you use to cut the holes?

RC-Captain

Thanks, I used a key hole saw to make the holes . I bought the set at a hardware store for 3 dollars or so. I would guess the pipe is AMERICAN made . I really can't tell 'cause I have nver seen CANADIAN pipe.

bkdavy

My Feedback: (1)

That looks like american pipe to me. I've used both. The american pipe has a second layer of plastic inside that has a grey color to it. Makes the fuse SIGNIFICANTLY stiffer, but also heavier. My canadian pipe fuses cracked pretty easily.

Rather than using the dowels as wing hold downs, use some wire coat hangers around the bottom with hooks bent at the ends. You can slide these all over, but when you get 14-16 rubberbands on them, they don't go anywhere until you crash.

Brad

RC-Captain

The CG is not found my moving the wing back and forth. There is an actual program for finding the CG in which you plug in the measurements for where you have your wing mounted. Thanks for the wire hook method tip , but I like the dowels which noticeably weighs less than the coat hangers. I am at 5.5 pounds dry and will give it a test flight today , soon.

EDIT: I forgot to mention I found a hole in my fuel tank when replace the metal engine mount for the carbon fiber or plastic mount. I know this had something to do with my not being able to lean out the engine from 1 1/2 turn out. I'm very interested in seeing the tach results now there is a new tank installed.

bkdavy

My Feedback: (1)

Check out Spadworld.com. You'll find that many spadders use the wire wing hold-downs until the plane is balanced and flight tested. Then the wire hold-downs are replaced with the dowels. This gives you the advantage of actually seeing how the plane handles at different wing positions.

Computers are nice, but they can only account for as much info as you give them. And the actual Aerodynamic Center can't be determined until the plane is in the air. Balanced on the spar is only a thumbrule.

Good luck! Anxious to hear a flight report.

Brad

RC-Captain

Well I got the plane off the ground made a left bank turn and then all hell broke lose. The plane became very uncontrollable and I noticed the the tail dropped (as I knew already it was tail heavy because of were I located the RX battery) and then I cut the motor and put it into a dive and tried to pull out but didn't have enough speed so the engine nose into the ground and broke the prop and the wing separated from the fuse and 2 of the nylon bolts holding the landing gear sheared right off.

SO the moral of the story is it takes allot of time and work to perfect these SPAD planes but once you get it right theres not looking back.

P.S. I haven't got it right yet [:-]

Muldoer

Being nose or tail heavy has nothing to do with where you place your gear...its where you place your wing in order to achieve balance. You could put a brick in the tail and as long as you slide your wing back enough in order to balance your plane on the spar, it wont be tail heavy...



EDIT: Oh dear gawd no....You cant expect to have a plane balance merely by calculating it...Yes I know thats how they do it on full size aircraft, but models are just the right size to do it PHYSICALLY and get a perfect CG perfect on the first pass. Read all the instructions on the Deb and DPS over on finding CG and use that method. CG calculators are good when experimenting and such...but when you have a proven design move the wing around as indicated.

bkdavy

My Feedback: (1)

For a good demonstration of what might have happened to your plane take a look at this discussion of the[link=http://142.26.194.131/aerodynamics1/Stability/Page7.html]Aerodynamic Center[/link]. Most model pilots think only about the center of gravity in relation to the main wing, since the aerodymanic center is generally about 25% of the chord. This can change depending on the airfoil employed. It also shows why nose heavy planes fly poorly and tail heavy planes fly once.

The real moral of the story is - for the first time builder - follow the proven plans - no modifications. Then experiment on your second plane. I'd never flown RC until last July. I built the Debonair per plans in a week (total build time about 4 hours). I soloed with an instructor after 4 lessons (I was ready sooner, the instructor just couldn't believe it).

I still have the Deb, and its a great plane. I use it for aerial video.

Brad

Muldoer

I second that...I dont understand why you've had so much trouble with spads...I built my first spad straight from the plans, followed the instructions to the letter and it flew perfectly on its maiden. No time is necessary to perfect these things, because the spads made from plans are perfect to start with.

RC-Captain

If this is true I feel sorry for every one purchasing ARF planes especially 3D planes as most 3D pilots move most of their gear to the rear of plane to achieve better tricks.

Now I know we are talking spad plane here but I'm applying every thing I know about regular balsa planes to these SPAD planes. It may not be soon but I will get this plane to fly right.

No disrespect but why? I flown many different planes and I am not just trying to fly a SPAD plane but a SPAD plane I designed work on and completed for perfect flight. The point I am trying to make is I don't have a problem flying planes , just constructing a plane from mer nothing and getting it to act right.

I'm going to move the battery out of the tail tomorrow after I make minor repairs and give it a go again.

P.S. I don't give up do I

bkdavy

My Feedback: (1)

To improve your chances of success, stick with the basic thumbrules. Moving equipment around to move the CG to the 25% of the wing chord may be enough, but if its not, don't discount moving the wing.

As far as ARFs, those planes have already been designed for aerodynamic stability. Its probably that the alterations of moving gear to the rear are only moving the CG rearwards slightly. This will still develop the unstable moment described on the website, but it is not so big that it can't be easily overcome by the pilot with slight adjustments. Get that moment too big, and its bad news. The size of that moment arm is determined by the distance between the center of gravity and the aerodynamic center.


I was simply trying to counter your point that Spads are difficult to build. They're not. Airplane design (spad or balsa), which is what you are apparently trying to do, can be difficult, with multiple considerations.

Best of luck, and keep us posted.
Brad

RC-Captain

I agree , but for me, only me , getting them to fly is where difficult steps in. I am going to put one of these ARF SPAD planes to the test. I will order it get it and put it together and see if I experience the same problems.

P.S. minus the fuse of course I have plenty of pvc pipe.

Muldoer

Thats because they CANT move the wing around in order to achieve balance. Thats how balsa planes work because they build the wing saddle in the fuselages. SPADs dont need wing saddles. Plus the plane you built is FAR from being a 3D machine! Stop applying balsa rules to spad planes...it just doesnt work. You must unlearn what you have learned [/yoda]

jessiej

Exactly, Muldoer. I don't see what some people find so difficult to understand about the concept of CG, but it is clearly (one would think) a big advantage to being able to bring the wing to the CG as opposed to adding/shifting weight to relocate the GC. Doesn't the "S" in SPAD stand for simple?

Perhaps if the CG were expressed as percentage of chord...Naw forget it.

jess

fireflynj

My Feedback: (5)

I have not built a SPAD yet, but didn't anyone notice that it looks tail heavy?
The Fuse is not cut like what it is shown as in Debonair plans, see http://www.spadtothebone.com/SPAD/De...ge3/page3.html

jessiej

I really can't tell by looking, firefly, but from the description of the flight characteristics tail heavy is a good bet. I don't understand why the builder didn't simply pick the thing up and see if it balanced somewhere around 25% back from the LE before he attempted to fly it as opposed to crashing and then thinking about the CG afterward.

I guess some folk either like to complicate things or perhaps they are just a slow study.

jess