The Radio Control Club of Detroit

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RCCD 2012 Scratch Build Project
Tips & Input from Participants

The following ideas are the result of e-mails between participants that are shared with the group.
Send any you would like to share to Iceman

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Updated 12/11/11:

Q1. I have seen different types of push rods. Which type would you recommend? Do you like a steel rod routed through a plastic casing which would be glued to the plane frame? Do you have any idea for minimum length?
A1. My choice for the elevator & rudder push rod system is a 3/16" O.D. plastic housing with a 2-56 steel push rod/clevis, 32" in length. The holes in the laser cut formers are 3/16" dia. ready for the 3/16" plastic housing. The ailerons are also 2-56 steel push rod/ clevis. The Throttle control is a 2-56 metal flexible cable within a plastic housing. I use EZ connectors to connect the push rods to the servo arms.

Q2. What size rear wheel would this plane need? 3/4" diameter or larger?
A2. The 3/4" dia. tail wheel will work, the original plans used a 1 1/4" dia. wheel.

Q3. What size/thickness & width fiberglass cloth would you recommend?
A3. The 2" width of the fiberglass tape is specified in the instruction. I cut a 2" wide strip from a old piece of .002" thick fiberglass cloth that I had. I used thin CA to adhere the f/g tape to the wing followed by a coat of medium CA.

Q4. Is there a special size of control horns needed to correctly build this plane?
A4. The control horns are medium size (approx. 1" in length) that are used for .60 size airplanes.

Q5. What would be the dimensions of the Landing gear on the sample plane brought to the meeting? [mounting width at plane]
[height: plane to axle][spread: width at axles]
A5. I used the "Dubro Super Strength landing gear" (no. 789). The spread is approx. 14 1/2". The height is approx. 4". The width that mates to the bottom of the fuse is approx. 3 1/2". Or, You can use a .09" thick alum. landing gear that is close to the dimensions of the Dubro landing gear. I used 3 1/4" dia main wheels.

Thanks again, for all your work to bring this club project together. It brings the club together and supplies all who participate entertainment.

Q6. Do you have a recommended landing gear and tailwheel assembly for the All-Star 60. Getting to the point where I need to drill holes and install "T" nuts.
A6. The original Four Star 60 kit didn't specify any certain manufacturer for the main gear or the t'wheel ass'y. The main gear they used was pre-bent .09 alum. with a 13" spread, and 4-1/4" in height( axle to the bottom of fuse.). 3-1/4" dia. main wheels were specified. The specified tail wheel is 1-1/4" dia., and a molded nylon bracket with pre-bent 3/32" dia. music wire. I used the "Dubro Super Strength landing gear" (no. 789). The spread is approx. 14" to 14 1/2". The height is approx. 4". The width that mates to the bottom of the fuse is approx. 3 1/2". The main wheels I used were Dubro 3-1/4" dia. super lite wheels.
I am using a tail wheel ass'y that I found at a swap meet. It has a 1" dia. wheel. It looks simular to a Dubro tailwheel bracket ass'y (no. 376) which also looks like the t'wheel ass'y. shown on the four Star 60 plans.


Q7. There appear to be scribe lines missing from the ribs.
A7. They somehow got dropped from the file during laser-cutting. Revised directions for this.

Q8. (Actually an observation) Hi Pete, I just put my wings together. I got to the point where I had cut the six ribs and was juggling those, together with the dihedral brace, plus spacing the brace at the bottom to leave room for sheeting etc and I thought I'd try something different. I flipped the wings over and tack glued the bottom center sheeting in place, making sure I glued the ribs to the bottom sheet. THEN I turned it all right side up and set the dihedral angle etc. MINUS the brace. I then glued the center joint. While that was all weighted and clamped I dropped the center brace in from above, glued and clamped it and then thoroughly re-glued all the bottom sheet joints.

Benefits I saw were as follows:
- Prior to installing the brace the cut ribs were supported by the bottom sheet, and therefore not flopping around and subject to possible breakage. They were also correctly positioned, held by the bottom sheet.
- The spacing below the brace to leave room for the bottom sheet was no longer necessary.
- No glue dripped down from the inside of the brace and ribs that would otherwise require clean-up before the bottom sheet could be applied.(I use carpenters glue, this is less important for those using CA).

Top sheets are now installed and drying, so other than the fiberglass center reinforcement, my wing is just about done!

If I was to do it over again, I think I would partially cut the ribs for the brace (halfway from below), remove the 1/8" half section, then glue on the bottom sheeting. When dry I would finish cutting the ribs. This would hold them in place while the sheeting was applied but would not create an awkward cleanup operation at the bottom of the rib where it was glued to the sheet.

It worked for me. How about you get one of the guys to try it out and see what you think?

A8. That's what's great about this hobby. There are different ways of obtaining the same results. Your idea sound good and obviously worked for you. You even had another way to accomplish the same thing as stated in your last paragraph. I bet, if we talked to another builder, he would have a fourth way of doing the same thing.
I don't think any changes are necessary to the instructions. I think your email exemplifies the various ways of building. It might entice the other builders to try using their own ideas and methods in the building process.

Thanks again for your input.

Q9. When drilling the holes for the servo wires in the top of the wing sheeting, try not to lose the wooden "slug" down the hole! It's a PITA to get out because that section is enclosed except for the servo wire tubes. Don't ask me how I know!!!

A9. I start off by laying out the location and the hole size I want (approx. 3/4" dia.). I usually drill a smaller hole, and enlarge it by first using a exacto knife cutting the hole larger with small cuts leaving small shaving. I then finish the hole by sanding the hole round, again leaving small dust shavings. The final step is to vacuum out the dust through the holes after both holes are in the top sheeting, thus no PITA. I won't ask you, how I know,

Q10. I was reading about building the four star 60 kit and modifications others have tried. Have you heard this one? From an RCGroups thread ... "the single most important "mod" to the 4-star is to drop the horizontal stab to the bottom of the fuse. The 4-star is a great flying sport plane, but exhibits a rather huge downward pitching tendency with rudder input. Dropping the stab to the bottom corrects this". Does this sound like a good thing to do with the all star 60 kit?

A10. I have not heard this one, but have never built a 4 Star before. However, I can believe the pitch to wheels in knife-edge flight. This is not uncommon for a low-wing plane. Conversely the Stik pulls to the "canopy" in knife-edge flight - common for a high-wing plane.

Lowering the horizontal stab may correct the tendency on the All Star, but it may also induce other tendencies: The horizontal stab will then be more likely to be affected by the slipstream of the main wing, especially at high angles of attack. And at very high angles of attack, you may loose elevator authority.

Instead of moving the horizontal stab', I find it pretty easy to correct this tendency with a transmitter mix: Rudder is Master and elevator is Slave. Elevator is programmed to go up with left or right rudder.

However, as Rattlesnake has stated before, scratch building offers you the opportunity to try stuff and see what happens. Good luck with whichever way you go.

Q11. The instructions suggest a starting CG point at 25% of chord, including the aileron? Is this the aileron at it's widest point, ie near the wing root. The chord tapers by more than an inch towards the tips. Same goes for the 5/8" up and down travel - widest point again?

A11. The simple answer is to calculate the CG at the midway point of the aileron length (33" divided in half) or 16 -1/2" from the outer edge of the aileron . Measure your wing cord at that point and 25 percent of the wing cord including the aileron is the starting CG point. This works out to be close to the CG shown on the original plans. As for the control surface movements (5/8" up and 5/8" down for the aileron), I assume it is also at the midway point of the aileron. The original instructions of the 4 star 60 reads as follows: "The control surface movements listed here are recommended for the first flights. These movements will provide the model with a fair degree of aerobatic capability if it is balanced correctly. Test flights may indicate a need for slightly more or less movement depending on individual model performance and personal preference."


 


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