rffs-100 flying

[muskrat]

I finally flew my skeeter tonight. turns great to the left and hardly at all to the right. I have equal throw on the rudder, no offset on the engine. The stabilizers are all square and line up fine with the wing. Any suggestions?? By the way, plenty of power with the kpoo.

[pease1]

Should fly fine both ways, does your rudder have counterbalance (fin ahead of the hinge line)

Also, try a little right thrust.

Al

[dhurd]

Muskrat,
I agree with pease1 abuot the motor thrust angle (the counter balance really isn't so crucial until you get into larger, heavier planes). We have found with the Lil' skeeter that the thrust angle for the motor can be critical. Usually about 3 degree to the right seems to work.
Let us know how it comes out.

Sincerely,
Dan

[muskrat]

thanks, Al and Dan,
I'll try the offset. I was also wondering about dihedral, I mean if I have enough. Wouldn't that make turning difficult also?
thanks,


jim

[Dave Robelen]

Hi Jim,
You originally mentioned a problem turning poorly in one direction. If it were a dihedral issue, the turning difficulty should be more equal. As Dan pointed out, sidethrust on many models can be very sensitive.
Regards, Dave

[muskrat]

Thanks Dave,
I wanted to ask you about hinges. I read your article on using hypo needles but have you ever tried sewn hinges on these indoor planes? I remember in the old days they always worked so easily. Thanks
Jim

[Dave Robelen]

Hi Muskrat (Jim),
I have used a variety of hinges on the little guys over the years. The sewn thread works fine, altough when dealing with light 1/32" balsa they can get a bit "tender". Overlapping hinges made from silk ala CL models work really well when applied with cellulose glue. The hingeline can be nice and snug with a very free action. I used the pin and tube method on the Pixel with the RFFS-100 because I wanted both free and precise movement, along with a gap between the surfaces for the rubber centering band to work well. Choices, choices---
Regards, Dave

[muskrat]

Thanks Dave,
I really appreciate the input.

jim

[Squareloop]

I wasn't sure about those rubberband hinges so when Dave mentioned old style cloth hinges would work I'd thought I'd try them. I used LW tissue (real light weight polyester) glued with a little Ambroid. Well, I did the elev first. I was disapointed with the result, only3/32" total movement. But not knowing what to expect from a magnetic actuator, (RFFS-100 instructions give no clue as to expected throws) I did the rudder. What a difference - like +- 1/4". Thought for sure I had a "bad" coil. Both surfaces "seemed" equally free but the elev did have 4 more hinge strips. So I cut it down to 2 sets and low and behold it worked almost as good as the rudder. So the lesson learned - well, certainly the hinge must not loan the actuator AT ALL, don't over hinge the thing and don't blame the equippment first when things don't work.

I'm installing the system in a twin boom, twin rudder pusher also loosely based on Anderson Greenwoods Model 14. If I can figure how to upload pics I'll send out afew. Joe

[gjohnson]

Yup,
Getting the hinges right seems to be the biggest challange. I think Dave used pin hinges on his Pixel. I recently made some pin hinges (my first) for my current project. I used 0.8mm CF rod for the pin, and the appropriate size aluminum tubing from Peck to go around it. Two complete hinges for a control surface, plus one rubber band for centering added 0.05g in weight to the model. Best of all, they move freely.

Here's a diagram. You cut four short lengths of aluminum tubing, and two of CF rod selected so the CF rod is a reasonably close fit inside the tube. Wick CA into the ends to fix the CF rod in one aluminum tube. After it's dry another equal sized length of aluminum tube is slid on to form the other half of the hinge. The control surface is cut out slightly to not contact one of the hinge aluminum tubes. And, on the other half of the control surface (i.e., the part that doesn't move) a corresponding cut out is made so it doesn't contact the other aluminum tube. Glue one aluminum tube to one side of the control surface and the other tube to the other side of the control surface. Use piano wire or a toothpick to apply CA to make sure none gets in the hinge itself. Finally, point the fixed CF rods in towards each other (or out away from each other) which prevents the control surface from being able to slide off. Then assemble the other hinge.

Some people use insulation stripped off thin wires and slip short lengths of that over piano wire. I just used aluminum tubing because I had it and it was a nice fit.

Gordon

[gjohnson]

Here's a picture of a pin hinge. Sorry it's kind of fuzzy.

[Squareloop]

Say Gordon have I missed something about the rubberband. Is it truely necessary for centering? On the bench the surfaces seem to center. Not airborne yet so what surprizes await? Waas up? Joe

[gjohnson]

The rubber band might not be needed. But, since it weighs next to nothing, I put one on anyway. I've also started balancing the control surface. I cut a length of piano wire to attach to the LE of the control surface air counterbalance section and kept filing it shorter till it balanced. Carl Martin told me he hammered a length of solder very thin, then kept trimming it till everything balanced, then glued it on the bottom of the LE region.

Gordon

[gjohnson]

Here's a better picture.

[dhurd]

Joe,
Our experience has been that the rubber band gives you more precision in flying. It not only acts as a self-centering mechanism but also gives you a non-linear effect. Because the more you bend the rubber the more force it takes to bend it further. IT's almost like dialing in exponential if you have a computer radio.

Sincerely,
Dan

[Squareloop]

Thank you Dan and Gordon for the tips. What an adventure this new world of micro-aviation (micro at least for me) has been. Here's just a few "fun" things that happened on this first attempt. I took great care to assemble the magnetics as per plans. Bent perfect wires for the magnets, centered everything just so. And it worked! But then one time I placed the model down on the work bench and picked it up but with a small screw driver stuck to the stab. No worries, I just pulled it away. Unfortunately the next time I look at the actuators (you guessed it) my beautiful magnet looks like its attached to a pretzel (still don't have it straight - I need to buy plastic tools!).

And woking with the wires! Well, I feel like I'm handling spider webs. I really feel like a bull in a china shop. But I love it. You know that's what's neat about our hobby - just when you think you've done it all, well you ain't see nothing yet! Love it just love it.

I'm not happy with the mess of wires and it seems such a hassel to plug and un-plug the wires. By the time I get the antenna and battery plugged in seems some tihng always comes undone. So I have this tiny switch that I'm wiring in to the battery circuit. That will protect against plugging the batt in wrong and should allow me to staright up the wiring.

Say, what do you do if you break one of those thin actuator leads? Solder, twist, what? And where does one find wire like that? I'm having fun and haven't crashed yet! Joe D

[Aeronutz]

make life easy for yourself

Make the plane around control system!

Soldered joints are more reliable that plugs

Charge the cells via two seperate legs of the undercarriage and then just plug in the negative wire from the control system to the negative on the cells.

Yes, use plastic tweezres. Neodium magnets make good bench pets ! Maplins sell plastic tweezers in the UK

Use 38 g copper ennammelld wire but they the wire that has low temp. enammel so it melts easy. Wire from motors a coils are high temp.

Use low temp. solder

Hold the wires with hair clips and BlueTak when soldering them

Dont work on a micro plane when you are in a rush, you will just get hot and bothered (migth as well be at work in that case!)

Develope a sense of humour - a good life skill

Mark