Guillows Curtiss Robin R/C

[Bill Gaylord]

I got this kit on Ebay a while back, and finally started on it. The die-cut parts almost fell out of the sheets like laser cut parts, and are above par in terms of accuracy, for die-cut. The 3/32" wood is a bit heavy and the model uses a lot of wood, making this model better suited for rc versus rubber power, if built out of the box.

[davidchoate]

Those old kits do seem to be Die Cut Better than now. And that wwod is strong, but I coukdnt see My Aearonca Flying On Rubber. Just too HeavY.

[Bill Gaylord]

Those old kits do seem to be Die Cut Better than now. And that wwod is strong, but I coukdnt see My Aearonca Flying On Rubber. Just too HeavY.

I think some of the old time die-setters were the best. The Guillows mini Hellcat is one of the best die-cut kits I remember, off top of head.

I decide to use a single BA 2.5 servo, after remembering that I would need an inline diode modification to reduce BEC voltage, if I were to use micro linear servos. They are commonly speced at 4.2V and do not care for 5V BEC supplies. I'm also less of a fan of micro linear servos, after having a few reliability issues with them. This setup uses .020" music wire for an aileron cable system, with a central servo in the upper fuse. I've used .015" in the past also, for ultralight builds such as the 16" Guillows Stuka. The idea will be to have an access door in the center bay of the cabin roof, for cable adjustment at the servo horn. I've used this setup numerous times before on micros, and the key is to pre-bend the wire, to reduce friction at the curved transition where the cable bends 90 degrees before exiting the wing to the ailerons. This setup was actually a breeze, compared to hiding the aileron cable servo in the radiator of a Guillows Rumpler biplane. The end result is not much heavier than using individual micro linear servos, as you only need one servo with this setup.

[Bill Gaylord]

Finished the Robin at around 4-1/8oz AUW, seeming to balance well with no added ballast. The double wing strut setup is always nice in that it allows you to precisely set dihedral and washout settings that will permanently hold. I need to try to fly this one soon.

[davidchoate]

Nice. I agree about the poor reliability of the linear servos. they seem weak. the most time i've spent on my current conversion has been tweaking the control rods and getting them set at an angle where they do not bind. I much prefer your setup with the 2.5 g servos. I learned the hard , but am using the linear servos one last time because I had it handy, and it seems to be working good . For now. Oh, I plan on trying youre aileron setup, but I got some of that Sullivan Golden Cable I was going to use. I always have binding trouble with sharp bends using music wire and tubing guide type set up. I got the Robin plan, but no plastic pieces. So I'm glad you posted ypur build. I cant wait to see it fly.

[Bill Gaylord]

Nice. I agree about the poor reliability of the linear servos. they seem weak. the most time i've spent on my current conversion has been tweaking the control rods and getting them set at an angle where they do not bind. I much prefer your setup with the 2.5 g servos. I learned the hard , but am using the linear servos one last time because I had it handy, and it seems to be working good . For now. Oh, I plan on trying youre aileron setup, but I got some of that Sullivan Golden Cable I was going to use. I always have binding trouble with sharp bends using music wire and tubing guide type set up. I got the Robin plan, but no plastic pieces. So I'm glad you posted your build. I cant wait to see it fly.

Thanks David
It is a bit of effort to eliminate binding issues with wire cable setups. I spent a while tweaking the curves in the .020" music wire, in order to reduce friction to the point where the ailerons center and servo does not "buzz". Without creating smooth curves in the wires that conform to the 90 degree transition point along the cable path, the setup would not work due to friction. Parkzone actually turned out RTFs like their earlier P51 that had that issue. The best solution for that model was to replace the wire with a Sullivan Gold cable. For this model, I added a drop of oil to the openings in the cable sheathing that creates the 90 degree bends, which helps a bit even further. The two problems I have with the linear servos is that even with an inline diode BEC mod, the voltage is generally still a bit above spec for 4.2V linear servos. The pots losing contact is the second issue, since they're susceptible to contamination and corrosion, as they are not enclosed in a case such as in a standard servo.

I brought my batteries in from the car and now have an exact AUW of 4-1/8 oz, which is fine for this model. The model balances perfectly with the battery installed. The Robin would be a bit of extra effort without the plastic pieces, since they save a good bit of detail effort. I was impressed with how well the fit together on this model.

[davidchoate]

I have no weight problems due to now using brushless and I have found the same setup as you to be the best so far. Although we use different brands, Its the same basic combo. My last thing is to set the dihedral when I attach the wings, I made xtra strong mounting points for the struts, and , on this model, I learned to use different glues. I now use elmers on any critical settings because of the longer cure time, I can undo a mistake before its welded in place with CA. I'm learning.

[Bill Gaylord]

I have no weight problems due to now using brushless and I have found the same setup as you to be the best so far. Although we use different brands, Its the same basic combo. My last thing is to set the dihedral when I attach the wings, I made xtra strong mounting points for the struts, and , on this model, I learned to use different glues. I now use elmers on any critical settings because of the longer cure time, I can undo a mistake before its welded in place with CA. I'm learning.

I need to learn patience like that, when gluing on wings. I had to cut off the right wing panel of my Cessna 150 and reset the incidence. If you're going to have a panel with more positive incidence than another, don't have it be the right panel as it will exaggerate the natural left hand banking due to prop torque. For this model, I taped sticks onto the flat wing bottoms, so I could view across them to align the second panel to the first when gluing it on. It still is a bit iffy, as you get only a few seconds to adjust the panel, using thick CA.

Ditto on the reinforced strut mounting. For this model, the front wing struts mount into slots cut into inset planking on the fuse, that are right at the corner of a stringer and fuse former, and the rear struts have wire inserted in the ends, that locate into holes drilled into doubled up hard balsa stringers. I used basswood for the strut material, since I like to land these planes into tall weeds that tend to break balsa struts.

[davidchoate]

I was going to try the wire thing, but thought my plane is a bit too small. But I did laminate the balsa wing struts with basswood 1/32" then sanded it to not look too thick. Like I said. I'm learning, but many failures along the way. Youre videos have given me inspiration at times. Seeing visual proof that these things can fly helped alot, and I know what to expect as far as handling.

[davidchoate]

Yeah Bill, I think you maybe over powerered that Cessna just a little. I put A 250 Eflite on my Edge which I'm not gonna fly anytime soon after youre review. The specs say it can power a 3D plane up to 150g's or a sport planr up to 400g's. And thanks for the link to the hobby place.

[Bill Gaylord]

Yeah Bill, I think you maybe over powerered that Cessna just a little. I put A 250 Eflite on my Edge which I'm not gonna fly anytime soon after youre review. The specs say it can power a 3D plane up to 150g's or a sport planr up to 400g's. And thanks for the link to the hobby place.

Yeah I think the Edge could use a different airfoil section possibly, as a micro rc flyer. Probably would need to be really light, to be much of an enjoyable aerobat at it's small size also. This litte Robin was entirely the opposite. It was really easy to fly and stable given that it was windy and hot, with the thermal effect seemingly making it want to really climb. Can't be the high wingers for micro conversions. Power wise at roughly 115 grams, this plane floats like a helium balloon at part throttle, with a motor similar to the Hexronik 10gm outrunner on 2 cells. I have some video here on YouTube that my friend took for me. He brought his 7 year old son along also, who hasn't seen models fly before this. Again, pardon the old camera and flying dot, but it least it gives some idea of how it flies.

YouTube flight video:
https://www.youtube.com/watch?v=BdspYqd ... e3uS3fLSoA

I also sculpted balsa manifolds for it last night, which it has proved it really deserves. They would look better using tubing, at least for the main pipe, but I don't want to effect the weight much since it seems balanced well.

[davidchoate]

Nice. seeing that Gives me complete confidence my Aeronca will fly. I am a little less AUW than you with an almost identical power setup. What prop works well on these 300 series?; They are all very similar in size and weight and design.

[Bill Gaylord]

The prop is a GWS 4530, which I've used on a number of comparable setups. The Heads Up RC site has a pretty good prop application chart for various motors, that can be used as a good baseline for any comparable motor.
I think the biggest hangup in getting these models to fly well, other than of course proper CG setting, is perfect wing alignment with no warps. The little C150 I built years ago was a perfect example of that, where it went from being basically unflyable to beginner easy, with a slight incidence correction. For this model I have maybe 2 degrees maximum of washout set in the panels, and the double strut setup is excellent for holding the settings. In a nice, calm evening situation, this model would be a perfect trainer once trimmed out, given the person has good sight.

[davidchoate]

Thanx for the tip. I sanded my plane tonight and put a prop on, and ran the motor to blow out the dust. And It has PLENTY of power. I think it would do about 30 mph on the ground. Its gonna fly. But I want it to fly well. and setting all this stuff right is whats going to make the difference. Like I said before, I have just been copying the angles and such off of RTF planes of the same scale and weight until I get a better understanding of it how it works.

[Smokin' Beaver]

Beautiful Job Bill!
What a classic.

- Phil