My Homebuilt RC Micro Paper Se5a

[liftline]

Ramping up again after the 4th. Hot as hell at home, I like to build early in the morning so I don't sweat on the paper. AC is used sparingly!

I've been looking into wire alternatives, and it's going to be hard to beat the 6 strand phone cable wire for price and weight. I may be able to obtain some incredibly light strain gauge wire from a friend, but I'm not counting on it and really, the weight difference would be little, it would just be easier to bend. Unless I can figure out a practical way to strip the insulator off the phone cable, possibly using an citrus based paint remover.

I'm moving the esc forward to above the lower wing to cut the amount of cable roughly in half.

Now that I think I know why the 2nd rc model was so tail heavy, I'm just going forward with a new 3 rd build rather than building a mule from scratch. I'll save the wings and tail surfaces from build 2 (recycled from build one) to make a mule if need should arise.

A few other minor alterations will be made to build 3.

The rudder area will be increased by 20% by extending it vertically to below the fuselage. This is actually accurate scale. The non moving vertical stabilizer remains unchanged.

The tail skid will be simplified and lightened, it was overbuilt since I added a small piece of music wire for the heavier RC model. Partial compensation for the larger rudder, but frankly the changes probably won't be noticed in terms of weight or cg, both pieces are very small.

The opening in the nose providing access to the battery will get a flange to make it stiffer, this will make it easier to close the hatch without accidentally bending it.

The latch on the motor hood will be landed, tape seems to work fine for now, it may come back in future.

The motor lug (popsicle stick wood) will be drilled out, not much weight to save, but it will look cool and I can say I did it.

I put the revised vertical stab and rudder together tonight, tested the hinge and dry fitted it to an old rear fuselage. Ah, it just looked right!

Measure the diameter of the wire. Get a small block of aliminum and drill a hole into it ever so slightly oversize to the wire. Mount an x-acto blade perpendicular to the hole so that it just goes into the wire enough as you pull it through the block. You can use a good 2 part epoxy, the Grey stuff that comes in the tubes, to mount the exacto blade. When you pull it through, the wire will split along the seam and it will peel right off. When you finish this, attach the longest possible piece of wire to a firmly fixed position. Pull on the wire and it will stretch. This stretching will in effect harden the wire, making it able to hold it's shape much better (1 strand at a time). The other benefit is, the wire will weight less as you have stretched it and the same wire covers more length. You could also just make the whole thing out of a expose "steel" tube and before it dries, mount the x-acto blade. You can then drill the hole right where you need it relative to the blade tip. Just an idea. You can also use 1 thicker strand copper wire and obtain similar results.

[liftline]

Originally Posted by Zathros

Measure the diameter of the wire. Get a small block of aliminum and drill a hole into it ever so slightly oversize to the wire. Mount an x-acto blade perpendicular to the hole so that it just goes into the wire enough as you pull it through the block. You can use a good 2 part epoxy, the Grey stuff that comes in the tubes, to mount the exacto blade. When you pull it through, the wire will split along the seam and it will peel right off. When you finish this, attach the longest possible piece of wire to a firmly fixed position. Pull on the wire and it will stretch. This stretching will in effect harden the wire, making it able to hold it's shape much better (1 strand at a time). The other benefit is, the wire will weight less as you have stretched it and the same wire covers more length. You could also just make the whole thing out of a expose "steel" tube and before it dries, mount the x-acto blade. You can then drill the hole right where you need it relative to the blade tip. Just an idea. You can also use 1 thicker strand copper wire and obtain similar results.

Genius! ME LIKEY

[liftline]

I save 0.048 g for every square inch I can remove from my patterns. .0075 g cm2. Easy enough to do, might save a fraction of a gram with due diligence. I have been a bit lazy with some of my patterns to save scissor work.

I just went to my plans and made 8 cutouts in my wing spar/spacer patterns (I call 'em sparsers). That knocks out 24.37 cm2 per left or right wing saving 0.183 g per wing and 0.731 g from all four. That's 4% of the current airframe wt! I would not have thought that! By applying the same approach to the short center sections of the upper and lower wings I can shave almost another 0.1 g. All told, these simple expedients can trim nearly a gram from all up weight. This is very low hanging fruit and worth going after! Would it be worth going after the control surfaces as well?
I'll check that out too. Generally pays to reduce the weight of the tail, most paper models build tail heavy in my experience.

This will be interesting. When I first moved into my house, there was this kid who would burn barrels of wire that he got from who knows where, probably 5 finger discount, and would stink up the whole neighborhood., so he could get the copper. When I found out where the smell was coming from, I showed him how to do it correctly. Then told him if I ever smelled that again I'd call the fire department. The fumes are very noxious! He told me he was able to do what took him hours, only a few minutes, and thanked me.

This economy has people doing all kinds of things to make a buck. What are you going to do? I try to help people. I don't have any money, just Brains.

[liftline]

I had less time to hobby than I would have liked this week end, but made some good progress, largely "virtual" rather than actual building.

After assembling the first revised wing I realized some minor changes could save more a bit more weight and result in a wing that is actually a bit easier to build and easier to build true. I actually pared a tiny amount of weight out of the ailerons! For each of the 4 wings outboard the center sections I have eliminated 30.9 cm2 of paper and
.235 g. By the time I get done with the upper and lower center wing sections I'll easily have axed 1 full gram.


I also took the time to thin the airfoil sections of the tail surfaces by 25%. This is not a significant weight reduction measure, but I hope the smaller profile it will reduce drag a bit. In earlier versions, the tail airfoils were arbitrarily made as thick as the wing aileron to simplify pivot and hinge production by using just one basic pattern that was "stretched" electronically.


The enlarged rudder turns out to be weight neutral; I managed to take out some unnecessary internal paper from the internal bracing of vertical stabilizer.

I'm taking a hard look at the undercarriage, I think there may be some weight savings there too.

The individual insulated phone wires are about 1mm in diameter, I'm having trouble finding tools small enough and precise enough to make a micro wire stripper.

Ah, the burning of insulated wire....One of my many college jobs involved scrap salvage. Our crew burned a huge pile of insulated copper wire in a field. It took a while to get going, and was pleasant at first and we speculated about making smores - but the heat got so intense we had to retreat hundreds of yards. Next day we had little copper piglets in the sand. Toxic foolishness of this kind was common back then.

[liftline]

I'm a bit behind schedule, but then again I need to earn the money to pay for this hobby!

All the Se5a airfoils have been revised and assembled for build No. 3. I'm really pleased with the results - I've never produced such true airfoils with such consistency and ease AND they are significantly lighter. The tail foils look better svelte, maybe it will pay off aerodynamically. That's the good news. The bad news is all my old flying paper model designs are obsolete!

Going fishing on the Great Lakes until Tues. Perch are biting well, so we'll eat. Bass not so good, but hope to catch a few. Walleye - not a chance!
It's always nice to sample the local vintages on America's North Shore Riviera, so we'll drink a few.

Hmmm! Fresh Freshwater fish. Don't even need any spices, maybe just some butter!

[liftline]

Good trip, and we never had to motor very far. I was the junior partner, but performed credibly.

Day one was excellent small mouth fishing. Between the two of us we kept a 14, 15 and two 17 inch. A few pan fish were taken as well. A late morning 18" small mouth was released and we were at the bar by noon watching soccer.

Day two slow but steady yellow perch fishing, caught about 50, mostly small to medium, just short of the limit. Threw back a number of trash fish and an apparently functioning coaxial cable that came up with the anchor. We beat a thunderstorm to the dock by about 10 minutes.

Flour, egg, cracker crumbs, a lot of black pepper, and yes a bit of butter. Mmmmmmm. Back to the grind.

Now I feel like eating some fish. Last good Trout I had was up in the Adirondacks. Mostly salt water fish in Connecticut and I don't trust the freshwater fish. We have a lot of pollution that has come down from Massachusetts and other states, and definitely our own concoctions, that has polluted the water and made eating freshwater fish questionable. Of course, the fish have increased in population, as people refrain from eating them. Go Fish!!

[liftline]

There is steady, but slow progress on the 3rd build. A lot of things are competing for my time and my studio is hot as Hades after 11:00 am. It's hard to do paper modeling when you drip all over the parts.

The airfoils are complete, and to a very high standard if I do say so myself. I built spares too. The new pattern wings take a little longer to build, but they are lighter, stronger and truer. I kid you not, I would have liked to make balsa wings this true, back in the days I did this sort of thing. The svelte horizontal and vertical stabs look great and maybe they'll reduce drag a bit.

I'll probably finish the new undercarriage tomorrow. Then, it's on to cracking the old bird, salvaging the guts and putting them into a new fuselage.

Slogging thru summer.

You ever consider posting some pics of this? It really sounds interesting. We're having one heckuva hot Summer here i Connecticut. You really notice it the second you start to move. I hate to admit, I have not modeled much lately, and considered what Allen Tam (Goodduck) has given me (one of a handful of his Savoia -S-21 from the movie Porco Roso), I'm not to proud of it, but the heat paralyzes me. It is printed and will be next though. So keep plugging away. You're far ahead of the curve!

[liftline]

[QUOTE=Zathros;927547]You ever consider posting some pics of this?

I'll borrow the good digital camera and see if I can get something useful.

[bzm3r]

Originally Posted by liftline

Here is the link:

http://s6.aeromech.usyd.edu.au/aero/...de_element.pdf

There are implementations of this available. I wrote my own in mathematica, but when I upgraded to Windows 7 I couldn't download my very old Mathmatica to my new computer. I may have an Excel implementation somewhere.

I just tested out the range of motions with the new settings and the elevator travel is much greater. Don't know how I could have missed it during preflght.

Hi Liftline,

Just a young newbie here, very interested with what you were talking about, but a bit disappointed to see that the link was down. Any similar links, or subject keywords I could be searching for?