Ragwing

My Feedback: (2)

Howdy,

I'm new to C/L, I started the thread a while back about 1/2A C/L trainer plans, and since then have built and flown one of Old Sourdough's Stunt Chimps with a Cox Golden-Bee/BW cross. The plane is a kick in the pants, I really like C/L, and though I am not too terribly accomplished with the model, I'm thinking of building something a little less trainer-like.

My plan is to take BMatthew's Cadet plans, and add a built up wing (now don't go and talk me out of this, I've already scaled a set of symmetrical wing ribs to fit the planform ), and remove the gear. I plan on powering it with a Cox Killer Bee or TeeDee or Medallion .049. The trouble is what to do about fuel delivery. My options for small tanks are limited, Brodak makes a few, and there are some Perfect tanks to be had on Ebay all in the 1/2 oz+ size, and I could make my own eye dropper tank. But I worry that any of these tanks aren't going to be very good for stunting. I'd really like the tank to be concealable, and maintenance free (I'm afraid you guys are going to tell me to run a bladder). What do you guys think?

Thanks!

Derek

Jim Thomerson

I'd suggest at least an oz of fuel. 3/4 oz with a TD won't get you through the stunt pattern, (which at the moment you are not concerned with.) An oz will give you a nice flight time. I've used the Perfect 3/4 oz tanks for fun. There are two 3/4 oz sizes, a smaller miniature and a larger regular. Yeah, sure, they are both 3/4 oz. I am fooling around with the idea of using a balloon, non-stretched, but havn't come to any conclusion yet.

Jim

gcb

Derek,
Brodak bought out the Perfect tank line and now manufactures them, For starters you can use a wedge tank (1 oz. as Jim says). Keep the tank as close to the back of the engine as you can for better draw. Normal wedge tanks cause the engine to run leaner as the fuel supply gets low. You may want to re-plumb it later as a uniflow.
I would not suggest buying used tanks.
The Medallion sucks fuel a little better than the TD. I'm guessing that the Killer Bee has about the same fuel draw as the Medallion (I don't have one).
Another type plane to consider is a sheet wing stuntable plane like the SIG Skyray (for reed valve Cox engines), or one of Dick Sarpolus' many Sheet wing planes (for TD or Medallion). They are easy to build, stunt well, very sturdy, and easy to repair.
I'm not trying to talk you out of building the "Cadet", just suggesting an additional option. I don't remember what the Cadet looks like but if it is somewhat like the Stunt Chimp you may find it overpowered with the engines you mentioned.
Good luck in any case, and check out those Brodak tanks.

George

Ragwing

My Feedback: (2)

Thanks guys!

I those brodak tanks sound great, they should eliminate a lot of hassels--I hope. And GCB, I think you're right, the Cadet would be just too small for a TeeDee, looking at Dick Sarpolus' desings, it seems like most of his stuff is in the 27" range, and the Brodak built up stuff is in the 25" range. Whereas the Cadet is only 17.5", so I'll need to do some enlarging. I'd like to stick witht the Cadet because the plans are free, and it looks good. Blown up 150% it will have a 26 1/4" wingspan which should do nicely.

Thanks!

Derek

BMatthews

Well, I for one think this is a GREAT idea.....

I'd love to hear about your mods for increasing the wing and tail areas. I gather I hit the cuteness factor just right for you with the original trainer?

As for the tanks you've got some good ideas so far. Another would be to make a mini clunk tank from a 35mm film container. I think those would hold about an oz as well.

I've recently been thinking about a 40 inch span 15 to 25 powered stunt version with the same look to the fuselage and tail.

EDIT:

For a TeeDee or Norvel 061 you'll probably want to go a bit bigger for the wing than 26 inches. Going back to the 1/2A stunters of the 80's and early 90's when they were popular they were making them as large as 36 inch span. A think a happy medium for a nice sport flyer would be a central wing portion of 24 x 6 and then add the round tips and flaps to bring the overall span to 30 inches and 7 inch chord at the root to 6 at the last rib (like the Flite Steak uses). This would give you something in the order of 150 sq inches of area which would be great for sport flying. To go with that I'd blow up the fuselage side plan by about 1.5 and increase the stab to be about 1.5x the chord and 2x the span. The elevator hinge would move to the point where the elevator is about 60% of the total area.

For the airfoil you want to use a stunt type airfoil but keep the thickness down a touch so the speed isn't compromised too much. But not so thin that the sharness of the corners is compromised too much. For a 6 inch chord I'd go for a maximum thickness of 1 inch for better corners or if you want something fast and groovy then perhaps reduce it to about 7/8. 3/4 is a bit thin I would think. For a shape I recomend the Eppler 473. Some buddies of mine used the similar 474 a few years back on a fast combat model design and found it to be very resistant to stalling in the corners compared to the other popular options of the time. I feel it would work similarly in this application.

Such a sport stunter would fly quick but not too fast and should turn on a dime. On 35 foot or similar lines it should be a treat to fly.

Hope these suggestions help you with your efforts.

Ragwing

My Feedback: (2)

BMatthews,

Yeah, the cuteness factor is spot on, if you go bigger definitely flesh out the fuselage, but keep the profile the same .

The film canister fuel tank sounds better and better, do you think I could put large doublers on the side of the fuselage and bore out a hole in the middle to fit the film cannister, capping it off with the firewall? Or would that compromise the strength of the fuse too much? I like the idea of having the fuel tank concealed, but looks aren't everything so I could strap it on the side.

It sounds like enlarging the planform by about 171% will get the plane up to 30" WS, and 7" cord at the root, and about 5" at the last rib.

The addition of flaps opens a whole new can of worms, I'll have to go searching for a good description of how they work before I know how to address that issue.

Thanks for the help,

Derek

BMatthews

Not REAL flaps. Just a constant chord wing with a triangular cheater addition to the trailing edge to make it look tapered. They did it that way on LOTS of models back in the early days.

The film cannister tank is super easy to make. Use a piece of sharpened brass tubing to cut some nice tight fit holes for your favourite silicone tubing to fit through. Insert the tubing for the clunk through the hole so it sticks out about an 1/8 inch. Then squeeze in a 3/4 inch length of 3/32 aluminium or brass tubing into the clunk weight tubing. THE pressure of the tubing going into the silicone tubing will seal it against the hole. Then just hook up your fuel line to the engine the usual way. DO the same for the Uniflo line that just goes to the outside of the cannister about halfway back In this case it'll probably be all metal tubing but with a 1/2 inch length of sealing silicone. Clear as mud?

If I make it a 15 to 25 size it'll definetley have a built up fuselage. In fact with a stunt tank on the sides of it you could probably do it for the 1/2A version. 3/32 for the sides. stringers for the rear deck and formed 1/16 for the forward nose deck. Flat 3/32 for the bottom.

I'm getting sort of enthused. Don't be surprised if there's a CAD sketch here in a few days..... Like I NEED another project.....

gcb

Bruce,
That is a neat way to seal the tubing hole. I would suggest aluminum, copper, or stainless steel inside the tank though, unless you anneal the brass.
If I remember correctly, to anneal brass you heat it until it glows, then quench it in water. This softens it (just the opposite of steel). This might prevent the pin-holes you often hear about.
Larry Renger did a whole article on using small bottles as tanks (in Flying Models, I think). On some, he used silicone to seal the lid.
I've been saving some film canisters (35mm and Advantix) for 1/2A tanks but so far haven't made one tank.

George

Old Sourdough

George,

To anneal brass, one heats it to a dull red color and then lets it air cool. The brass may then be bent to almost amazing angles. Bending the brass more than once or twice, however, causes it to work harden, requiring another annealing in order to continue to bend or re-bend it.

Perhaps the best option would be to purchase the copper (It's fairly bendable as delivered and it does not corrode like brass often does in fuel.) tubing available from the K&S display at the local hobby shop. The copper will work harden as well, but usually not before the desired operations have been performed.

Paul

gcb

Thanks OS,
I normally use copper when I plumb tanks now. When I used brass I would heat it when I needed to bend it but I always bent it while it was hot. Sounds like you can start the torch at one end of a piece of tubing and slowly move the flame (or the piece if you are holding the tubing) slowly through the length of the brass tubing and it should be ready to use for tanks.
Now I wonder what metal softens when you quench it. I know I read that somewhere. How about aluminum?
I remember a tip about inserting a piece of nylon weed whacker string in tubing before bending so it won't collapse.

George

Old Sourdough

=====================
Derek,

I totally understand your desire to build and fly a "less trainer-like" airplane. Please allow me to offer some suggestions. First, don’t give up on that Stunt Chimp just yet. It is capable of taking you through learning the basic CL round maneuvers (inside and outside loops, lazy eights, etc.) and inverted flight at a lower cost (financial, crash damage and repair) than those planes with built up wings. Additionally, you have not mentioned which lines you are using. If you’re using the "standard" Dacron 1/2A lines, try finding and using .008" braided steel lines of 35’ to 42’. You’ll be surprised at the difference that using these lines will make. They have a great deal less drag and stretch than Dacron, which will result in a much higher degree of control for a given input.

Secondly, before spending the effort to redesign and build the Cadet as a built-up winged plane (My apologies to Bruce!), have a look at the Brodak line of 1/2A planes. Most, if not all, have the built-up wing you seek and will fly pretty well with your current .049. Brodak makes a quality product with a well deserved good reputation. Most of Brodak’s 1/2A planes have a scale, less trainer-like look, too. Check out the offerings here.

[link=http://www.brodak.com/shop_products.php?catagory=181&maincatagory=2&Submit=View+Products]Brodak 1/2A Planes[/link]

Lastly, I would recommend that you start preparing to move up to larger planes in the .19 to .40 sizes. If you do continue to fly C/L planes, you’ll want to do this. While the investment in a kit (or kits) and an engine (or engines) and other items necessary to fly them is quite a bit higher than it is for the 1/2A planes you’re currently enjoying, there are significant advantages to the larger planes. They are generally a bit more stable; they fly relatively more slowly (the larger diameter circle makes the plane seem to be flying more slowly) giving one more time to place his maneuvers and "fly" the plane through them more easily. The larger planes are affected a great deal less by wind, and can be safely flown by even novices in breezes that would have (or should have!) long since grounded 1/2A pilots, thereby increasing the available window for CL flying.

The investment for the larger planes can be cut significantly if you have some R/C engines within the size range I’ve mentioned by building a suitable plane and flying it with your R/C engine(s) with the throttle held open. You can also keep your eyes and ears open for deals on C/L engines and planes. Check local R/C swap meets for deals for those who have "graduated" (NO FLAMES, PLEASE!!) to R/C and, in their own minds, have no further need of those C/L "toys." You can often obtain lines and handles as well as kits (sometimes even well-built planes that are ARF) and engines. There still are, believe it or not, some deals at eBay as well in the "For Sale" sections of the various C/L Forums on the ‘Net.

I am not trying to talk you out of the Cadet redesign project (the "cuteness" factor is definitely there!), only to suggest some practical, viable alternatives. Whatever you decide to do, keep asking questions. Seeking and heeding that advice which seems right to you from those with more experience in C/L flying will make your learning curve steeper, enabling you to progress faster than those of us who started without help and made a lot of mistakes on our way to the points in our C/L "careers" that we have reached today. While I learned a lot from those mistakes, they definitely affected my progress, sometimes to the point of being so discouraged that I would put down the handle and go play solely with my HO Scale trains for a year or three!

BMatthews

Good points about the annealing. I do it so automatically after all these years I forget that others may not know about doing it. When I do it I heat it to red and then wave it around in the air for a moment until it's back to black and then dunk it in water so I can carry on. The water quench, even from red hot, will not harden it since this is not a carbon bearing steel. The metallurgy in this case is quite different.

OS, no slight taken. I learned much of my early stunting on a Goldberg Stuntman 23 that is almost a carbon copy of the Stunt Chimp. I totally agree that with longer lines there's still much to be learned. Of the Brodak models the ones that look the most "stuntable" to me would be the Baby Lightning Streak and the Baby Flite Streak. The Baby Clown doesn't look TOO bad but at 136 sq in's the wing is a bit smaller than I would like to see. The others, aside from the Pathfinder which is so big that it would require special care, look like they share the same "smaller" wings and have smaller tails for more of a light duty sport flying model. I'm sure the rest are stuntable with a rear enough balance but the first two are certain choices if you want to rip up the sky.

As for the Cadet I played with a blown up stunt type version but the "look" seems to go. Or maybe I'm just not in the artistic mood. All my other sketches lately look like mud too. It's up to you now Ragwing....

Ragwing

My Feedback: (2)

Old Sourdough,

Thanks for the advice. I haven't given up on the stunt chimp yet by any means, I've been trying to fly it as much as possible. And I have yet to teach the owner, the 9 year old that I built the plane with, how to fly it. So it will get a lot more use for sure--especailly when finals [:@] end on Wednesday. I have some 70' .008 lines that I plan on cutting down to a pair of 30' and 40' lines, so I will certainly try them on the Stunt Chimp.

As far as going to a kit, I have no doubt that going to a Brodak kit would save time and maybe a bit of frustration. But it would cut down on the fun too. I'm the type of stubborn person who likes to do everything themselves, and cheap . Last night I went to the hardware store and bought all the widgets necessary to build a nice C/L handle, because I think I can build one as good or better than what can be bought (and there is several hundred board feet of Black Walnut in the garage-a black walnut handle would look soo much better than one of those cheap-o plastic ones). And that is where a big portion of the fun is for me. Thats why I want to redesign the stunt chimp. I've built several planes from plans, so I figure this just gets me one step closer to scratch building.

Right now all the engines I own are two dozen 1/2 A cox engines, that is where my interest is right now (I don't know why). But If this project goes well I could see my self going to something bigger in the C/L realm (like a Smoothie [8D]). Greater line pull and slower speeds has its appeal (but I'm used to being dizzy [:'(], its gotta be hilarious to watch...). But for now, I'm plagued with way more projects then time or resources allow.

Thanks for the advice, I understand your intent. This forum is such a great resource, I would be flying blind without help from people like yourself, BMatthews, Jim T, Gcb and all the other guys who help so much here. I doubt I would have ever tried C/L if it hadn't been for all of you saying how much fun it was, in this forum.

One more question before I hit the books, how much should a 30 inch 1/2A stunt plane weigh?

Thanks again,

Derek

Jim Thomerson

That depends. Lighter is gooder. If you have a reasonably thick airfoil and a good TD, 10 oz will fly pretty well. 8 oz even better, and 6 oz fantastic. If your are more or less designing your own, build one, then see what you think could be better, and make another one.

Jim

Lee MRC

Ragwing, I have been reviewing your corrospondance and noticed the comment about utilizing black walnut for control handles. To eleminate the possibility of breaking with the grain be sure to thickness plane three picies with alternating grain directions to 1/3 of the total desired thickness (usually 3/4") and laminate to avoid any potential possibility of having only one control line on a two line system. Really, really hard to control that way! Hi Hi Keep us posted.



Lee MRC