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RCCD 2011 Scratch Build Project - Tips

Please send tips to the Webmaster. As you are building your Stick, if you have a good idea to share with the other builders, send a picture, a sketch, or a description and we'll post it here.

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Workshop Tips:

Work Surface Preparation:
While waiting to start the actual construction of your Ugly Stick, the work surface to build your plane on can be prepared. The attached is a suggested means to accomplished this task. (from Pete)

Some useful Q&A (from e-mails to Pete):

Q1: From your experience, is there a recommended engine for this size Plane? I thought I heard that a 60 size plane, usually needs a 60 size engine.
A1:This plane was originally designed as a .60 size, two stroke, fuel burning, engine powered airplane. Any .60 size, two stroke, engine would work. The design formula (main wing area, rib shape, weight, CG location, decalage, etc.) worked for the original design, so what we are building, should also work. Joe T. "Fence Post" is using a .55 and it flies with authority, but he made his plane light.

Q2: I see from the picture on the RCCD Home page that the engine is rotated 90 degrees to the left or Starboard side, Why? What advantages does this offer, vs straight up?
A2: There a couple of reasons for the engine rotation. Mainly for looks and partially for function, when and if you add a cowl. Another reason is to have the muffler and exhaust directed down away from the main wing and fuselage........ and Personal choice.
From Iceman: mounting the engine on its side also makes it easier to get the center of the carb' in line with the fuel tank (see also question # 4)

Q3: If the engine is rotated, is the fuel tank also rotated 90 degrees in the same direction?
A3: No

Q4: The fuel tank floor board is not shown, is there a recommended position, height that it should be?
A4: As with any engine that does not have a fuel pump, you try to line up your fuel tank pick up in line with the engine carburetor.

Q5: 5th- The wing length is optional to the builder, by making it longer I would get more surface area, will this make it fly better? Would the added weight (I'm not sure how much) make a difference in engine size?
A5: The larger wing area would give the plane more lift. The added weight would not noticeably affect the engine size. Most of the planes that we fly are overpowered compared to the full scale aircraft.......... some would argue----- Never enough power????

Q6: (a) I noticed in the full size plans that the push-rods criss cross in the middle of the fuselage. I also noticed that the plywood inserts (elevator) call out for the criss cross. What would happen if I did not criss cross them but took them (push-rods) straight back from the Servo to the control surface. I would move the elevator insert to the other side.
(b) Also, What would happen if I didn't use dowels as my push-rods but metal 44 size wire?

A6: (a) Your question regarding the push rods is an open ended question and a book can be written to cover all the servo/ push rod scenarios. The servo locations play a big factor in using different styles of push rods. Some builders place the servos toward the rear of the fuselage using wire extensions and short push rods. This would help balance the CG with less dead weight. If the plane is set up for trike landing gear, you would have to consider how you would control the steering for the nose gear. If you were to use one servo for both rudder control and steering for the nose gear, the placement of the servos would be in the location as shown in the pictures. The crossing of the push rods is just one way of handling the push rod. If you study the dimensions shown on the drawing for the hinges and the plywood insert for the elevator, you will find you can change which side the insert is on, by simply flipping the elevator over. The hinges should still fit in the hinge slots, but the insert will change sides.
(b) I use 1/4" dia. wood dowels to eliminate any deflection or bending of the push rods. If you use wire only, you would have to add support for the wire along the full length of the wire to eliminate the deflection or bending. Not advisable. I found flex braided wire in a plastic tube and/or plastic tube within a tube also has issues, so I avoid using them.
Another Opinion (Iceman's): As Rattlesnake stated, a book can be written on this. He covered the advantages of the stiff wood pushrod. Its disadvantage is its weight, especially in a hard landing (or worse) can strip servo gears. A metal pushrod with 2-56 thread on one end, running in a plastic tube works OK IF the tube is firmly attached to the fuselage and can not flex at all. The wire pushrod MUST slide without restriction. For this to be successful, the tube shroud run as close to straight as possible and be secured to the fuselage in at least two places. Three or more depending on length.

Q7: The engine cowling we make up later, or am I missing something.
A7: The engine cowling is optional and not required to build or fly the plane. It is simply for cosmetic reasons. If you look at the ARF ugly sticks, they come without cowls. Since this is your first attempt at building, my recommendation is to keep it simple and not use a cowl at this time. This is an item that you can add to your plane, if and when you decide to add a cowl.

From Hollywood & Lightning:

Use T.E. Stock

To avoid a lot of sanding on the trailing edge (T.E.) remove 3/4" from the rear of each rib & use 3/8" x 1.5" T.E. stock instead of the sanded 1/4 x 3/4 stick.

If you have not yet started wing construction, run a stack of ribs through a band-saw or similar, cutting at right angles to the bottom surface of the ribs.

If the ribs are already glued in, use a razor saw and one of the blocks that are used for spacing so as to keep the saw cut 90 degrees to surface.

Then install a 3/8 " x 1.5 " trailing edge stock. This basically means that the TE will be the same size by the time 1 1/2" TE stock is added

 

Pin Clamps - From Snapshot

At the ground school, Don brought up using pin clamps in construction. This information may be helpful:

For wood models there is nothing simpler or more basic than pins. There are a variety of types but the kind most modelers prefer are T-pins. These come in a few sizes. Usually the pins are put directly through the piece of wood being held in place. In some cases they may be criss-crossed over pieces rather than through them.

In addition to pins I use a product made by Rocket City called Pin Clamps (these are now sold by Nelson Hobbies*). These are small plastic disks that fit tightly onto a pin and are used to spread out the clamping pressure. I really like them.

* From Maverick - Nelson has now closed. I have found another place to get these Pin Clamps ( address below).

https://www.a2zcorp.us/store/Category.asp?Cguid={4A8B2991-92B2-4BDC-A024-6E322FB7D32F}&Category=ModelTools:Pins

For smaller models, such as rubber powered airplanes, dress makers pins are more appropriate because they have a smaller diameter.

Pins do not stay sharp forever. It is a good idea to buy new ones every so often. I can not say how often because it depends on how many kits you build, but they are inexpensive enough that you can dump your entire supply and buy new ones when needed.

More thoughts on Wing Span (WS)

Q8: I'm going to start building the wing soon and would like your input on the span I should go with, don't know if the shorter or longer span would be better. My thinking is the longer version. I really don't care if it weighs a little more.

A8: This project is about learning and trying stuff, so I am not going to recommend a wing span for you; rather explain what to expect and let you make an informed choice. Rattlesnake may have additional thoughts on this. Here's how to look at it:  The extra bay on each wing will not add much weight at all.  At a guess, about 4 oz.  So to look at two possibilities.  60.75" and 67"......

Chord (in) 14.00 14.00
Span (in) 60.75 67.00
Area (sq in) 850.50 938.00
Area (sq Ft) 5.91 6.51
Weight (lb) 6.50 6.75
Weight (oz) 104.00 108.00
Loading (oz/sq ft) 17.61 16.58

Wing Loading chart:

Wing Loading Type of Aircraft and Skill Level
(Oz./sq.ft)
5-10 Piper Cubs, powered glider
10-15 Sport flyers
15-20 Sport Scale, sport aerobatic
20-25 Fast sport, aerobatic
25-35 Scale, larger twins
35 & up You better have fast reactions

So both still fall within the "sport scale, sport aerobatic" wing loading, but the 67 inch wing span is closer to sport flyer and therefore will be able to fly a bit slower before it stalls. So what else to consider?

  • The longer wing span may be harder to fit in your vehicle.
  • If you build heavy (lots of glue, extra reinforcing, bigger wheels, trike gear, big engine, etc.) go for the longer WS
  • If you were installing a small engine/motor (like a .46), the short wing span and therefore lighter plane might be better.  Big engine/motor --> longer WS.
  • Shorter wing span will start and stop rolls and spins a bit quicker than a longer wing span.
  • Longer wing span will be easier to see in the air (assuming same color schemes for both)
  • Longer wing span may float a bit more on landing.  Nice on a dead stick!
  • Pattern planes tend to be "square" (wing span equals fuselage length).  Piper Cubs have much longer wing spans than fuselage length.
Confused?  Toss a coin!  You really can't go wrong with this plane.

A couple of additional comments regarding the Ugly Stick design (from Rattlesnake).

The above explains the technical side of the wing options, and the list of considerations regarding the plane is spot on.

As is clearly pointed out in his technical comments regarding the wing spans and wing loading, the overall numbers or results all fall within the sport flying classification, as the plane was originally design to be. The semi-symmetrical rib section also plays an important part in it's flying abilities. The original design of the airplane is basic and forgiving allowing for the different modifications. The wing span options give the individual builder the latitude build the plane and to say, " it's to my specifications, design and look".

An important factor is to make sure the plane's CG is balanced correctly. (This remains the same as long as the wing chord remains the same. 11.2" from the firewall as long as you did not alter the firewall location! You can always figure on a CG to be 25% to 30% back from the leading edge on a straight wing like this. Or use the CG calculator in our main Tips and Hints page for any wing, even swept, tapered and biplane wings.)

Do your thing, and have fun doing it.

Thoughts on Balancing your plane:

VERY IMPORTANT - The CG dimension given in the instructions will result in a tail-heavy condition. DO NOT USE 11.20 INCHES FROM THE FIREWALL. For your first flight, use 25% of the total chord. The Stick wing has a constant chord, so measure the distance from the leading edge (LE) of the wing to the trailing edge (TE) of the aileron; calculate 25% of this; place two pieces of masking tape on the wing on either side of the fuselage at about this (25%) distance back from the LE and accurately mark the 25% location on the masking tape; Also mark the 30% location for reference. Depending on your aileron width, 25% and 30% should be about 3.5 & 4 inches back.

I try to avoid adding weight to balance my planes at all costs. For glow planes I locate the receiver battery pack, the rudder & elevator servos, and cowl after I have everything else installed, but before I start the covering. I temporally place them then lift the plane with a finger on each 25% mark. I move the items around until I get the plane to balance.

If the plane will be tail heavy, I install the battery as far forward as the design allows. Even in the tank area or cowl if there is space. The rudder & elevator servos go as far forward in the wing opening area as possible. If still tail heavy, I will add spacers between the firewall and engine again if the design allows. If all this fails to achieve the desired balance, a heavy spinner nut can sometimes help.

To correct a nose-heavy condition, rudder & elevator servos can be mounted near the tail, either on the surface, or behind a hatch. The battery pack can be located in a belly hatch between two formers. If it is not too late, you may be able to mount the engine as far back on the engine mount as possible (but make sure there is clearance for fuel hoses. You may also be able to switch from a trike gear to a tail-dragger configuration. This eliminates the nose wheel weight and adds tail wheel weight.

For electrics, in addition to the above, the main power battery pack can usually be moved fore and aft to achieve balance. The addition of dead weight is the last resort.

A nose-heavy plane flies poorly. A tail-heavy plane flies once! For your first flight avoid the condition ... "A tail-heavy plane flies once!". That is why a 25% balance point is suggested. But after the first flight don't then ignore the first part of the adage .... "A nose-heavy plane flies poorly". A nose-heavy plane will stall at a higher speed, have to land faster, will change pitch a varying speeds, will not roll as straight as it should, will require more down elevator when inverted, and generally not be as pleasant to fly as a correctly balanced plane.

Take the time to get the balance right. This can only be done making slight adjustments and checking the results. Ask for help if needed.

 

 


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