Last week’s column on scaling stereotypes was some of the most fun I’ve had writing for Big Squid. Based on reader response, it would seem that it was the case for many of you as well. So with Axialfest going on this weekend and the odds that some news will break during it (outside of the […]
Last time I shared the story of how I got this PT-19 model and chose to do this restoration project, and we made a good start looking at things that were wrong with it (and needed to be fixed). This time we’ll get in to some serious fixing.
PT-19-24 I used a razor saw to ensure accurate edges on that cutout. I need to inset a block big enough to include the handgrip opening (and some “backing”) I’m going to make because the interior of the wingtip is not solid far enough back to contain the hole.
PT-19-25 I measured and cut out a block of balsa to match the dimensions of the cutout, with some overhang left “to sand on”. On a job like this it’s a good idea to sort through your available wood and pick a piece that’s a close match for hardness with the wingtip you’re going to attach it to. This will make it a lot easier to avoid lumpy transitions when you do the finish shaping. As the eventual cutout will have radiused (round) ends, I’m beginning the cutout using a 3/8” drill.
PT-19-26 The next step is to use my Dremel scrollsaw to make the two linear cuts that join those 3/8”holes.
PT-19-27 With that done I can glue the roughed-out handhold block into the wingtip.
PT-19-28 Now I get to shape the insert. I’m cutting the outside contour first using coarse (80-grit) paper and being very careful to retain the curvature of the arc that defines the full scale wingtip outline.
PT-19-29 Now all I have to do is match the surface of the inset block to the rest of the wingtip. A No. 11 blade is a good way to make a serious start at that.
PT-19-30 Now I’m back to using the 100-grit block to true-up the edges of the new assembly.
PT-19-31 Some careful pressure with another piece of 100-grit held loose in my hand smooths the outer radius of the tip.
PT-19-32 I saved the fussy part for last. The inside of the handhold is radiused all around, top and bottom. I started that finishing job using a new No. 11 blade and making lots of SHORT, shallow cuts.
PT-19-33 And the call goes out once more for “Sanding Block Man”! This time an ordinary hobby knife handle turns out to be exactly the right diameter to fit 1/5 scale PT-19 wingtip cutouts with some 320-grit production paper wrapped around it. Actually there are no secret tricks to doing a shaping job like this…it’s just a matter of knowing exactly what you want the result to look like before you start and then disciplining yourself to work carefully and deliberately until it gets that way.
PT-19-34 When I removed the various control surfaces while stripping the old plastic covering, I elected to cut out all the old pinned, tab-type hinges. To get them out cleanly I had to take some extra balsa along with each one, and that left open slots like this one in the right wing aileron cutout, that need to be dealt with before I can do anything about installing new hinges.
PT-19-35 The little narrow cutouts I’ve made aren’t big enough to seriously weaken the various control surface edges I cut them into, but they must be filled in so the new hinges won’t be flopping around in oversize holes when I want align them precisely. All I need to do is add tight fitting inserts, or plugs, of balsa of comparable hardness to the surrounding structure and make sure they stay inserted. A generous shot of ZAP does that job here.
PT-19-36 Now I can use an 80-grit sanding block to cut each hinge slot insert smooth and flush with the surrounding surface. With this done, I can later mark and cut new hinge slots as if the old ones had never been there.
PT-19-37 With all the structural repair and modification done to the stage that the outer surface of the wing is complete, the next step is to create a finish. In this case I’m going to use lightweight (3/4 oz./sq. yd.) fiberglass cloth bonded and sealed with coating epoxy. The shape of the PT-19 wing allows me to cover the entire top (or bottom) surface of each wing panel with a single piece of glass cloth. Here is my working piece for the top of the left wing. Notice that I have left a generous overhang to hold on to and to wrap around all those edges. I’ll cut and overlap the “extra” cloth in the aileron cutout to reinforce that part of the structure.
PT-19-38 Here’s another look at “dry fitting” the glass cloth before I begin to use the epoxy. This is the underside of the left wing. I’ll stretch and smooth that folded-over section of the material back across the exposed portion of the balsa surface, and then…
PT-19-39 …it’s epoxy time! I’m using ZAP surfacing/finishing epoxy mixed exactly per instructions and then thinned by adding 25% of the epoxy’s volume of denatured alcohol. The viscosity of the thinned epoxy is just right to wet the cloth thoroughly and penetrate into the underlying balsa, and is just thin enough that it is reluctant to “puddle” on the surface and cause excessive material build-up. You can see that I’m brushing “out” from a definite starting point (in this case the center of the wing), smoothing the epoxy mixture and working out ALL the bubbles and wrinkles as I go along.
PT-19-40 Remember that working sheet of fiberglass cloth you saw lying loose on the left wing in image PT-19 31? This is how it looks all brushed down snug against the balsa wing skin with my alcohol-thinned epoxy mix. You can see how easily the weave of the glass cloth lets you work it around the tight folds and compound curves of the wing panel and tip. I worked it down into the handhold cutout as far as it would go without forcing and saturated that area with plenty of epoxy. I’ll trim that cutout, along with the wrapped-over edges, after the epoxy has cured completely.
PT-19-41 This is the underside of the wingtip showing you how I wrapped the cloth around “past center” on every edge.(Yes, this happens to be the right wing). The idea is to set up for a generous overlap when I glass the remaining surface. Next, though, I get to trim it.
PT-19-42 When that happens it looks like this. A piece of 100-grit paper in my hand easily cuts away the unattached/unsaturated (extra) glass cloth right back to where it’s properly bonded to the balsa surface.
PT-19-43 Off camera I finished glassing the rest of the wing and trimmed all the edges just as in image PT-19 36. The next step in finishing the wing will be lots of primer and sanding, but before I get into that I’m going to re-install the flap and aileron servos. They’ll be going back into their original mounting locations, but on modified mounting plates that enclose the entire servo. (Remember image PT-19 4?) Here’s how my Airtronics servo fits onto a pair of spruce mounting blocks that I previously measured, cut and ZAP’d to the 1/16” plywood plate that works as both the servo mounting tray and the cover plate.
PT-19-44 This is how all that goes together. I mounted the servo to the blocks using the off-the-shelf mounting screws that came with it. Inside the wing a servo extension cable reaches all the way to the center section where it will be accessible for hook-up.
PT-19-45 A little diversion…I need the aileron horn in place to line up the pushrod exit hole in the wing skin. I have marked a line directly back from the servo output to locate both the pushrod exit opening and the control horn itself. Here I’m using a small chisel to open a hole in the 3/32” balsa sheet aileron skin for the rectangular base of the nylon control horn to seat into. (I prepared for this earlier by building in a wide basswood block INSIDE the aileron to provide a strong mounting base.) The next step is to attach the horn…
PT-19-46 I made punch mark pilot holes for the two screws that are furnished with the horn and seated the entire assembly into SLO-ZAP.
PT-19-47 With the servo mounted and the aileron horn in place I was able to determine the dimensions of the pushrod to go between them and locate the hole that permits it to pass through the wing skin. I started with a nice pointy No. 11 blade and now I’m using a round wood rasp to put proper radiused ends on the opening.
PT-19-48 All closed up it looks like this…not dead-on scale, but close.
PT-19-49 I tossed out those clunky plastic landing gear strut fairings, but retained the 7/32” steel wire main gear legs that came with the model. As you can see here, I recessed the surface of the ordinary torque-mounting hardwood landing gear blocks that were already in the wing, mounted the LG legs with the usual metal clips and screws and then covered the whole thing up with Stits Lite Fill epoxy. (This is nothing but a concession to the scale fanatic in me. It will screw up access if I have to do repairs, but hides the non-scale hardware. If I had designed this model from the start I would have come up with a more elegant solution to hide the torque rods. This is a good example of a place where you have to decide how far you want to go in modifying an existing airplane vs. starting over). …THEN… with all that done I cut the gear legs off about 1” outside the bottom wing skin. What you haven’t seen yet is a set of Robart Robo-Struts that will attach to the protruding legs through a pair of machined strut adaptor fittings made for me by my friend Jim Miller. (Again, remember that I’m playing catch-up. This is my solution to restoring an existing model to bring it up to the standards I wanted).
PT-19-50 Now you see ‘em. I’m using a long piece of steel wire that matches the axle shaft diameter to line up the axle mounting holes in the ends of the struts with each other while I use an Allen wrench to lock down the set screws inside the adaptors. This, along with the red “permanent” Loctite you saw me adding in image PT-19 43 will keep everything in place during normal flight operations.
PT-19-51 Here’s a sneak peek at where we’re going…the left wing of the finished airplane.
PT-19-52 We had a look at the empennage (tail surfaces) earlier. As I mentioned, the problems I have to deal with included a film covered horizontal stabilizer instead of sheet covering of some sort to represent the plywood on the full scale airplane, and the vertical-fin-to fuselage fairing. I’m not sure how well you can see that in the photos (it’s the blue part in image PT-19 5), but the fairing on the model as I got it was some balsa block sanded into a sort of lumpy, convex bulged-out shape. It’s SUPPOSED to be a concave curvature that flows cleanly from the vertical fin into the horizontal stabilizer and the rear fuselage deck. Using my Paul Matt reference drawings and some full scale photos, I made sure I knew exactly what shape I was trying to represent, then determined that all the material that needs to be there for it to be right was already in that original lump. In other words, all I had to do was to cut and sand away excess balsa until the shape became correct. Here I’m just at the end of that process, with only finish sanding left to do on the corrected fairing.
PT-19-53 Here’s a good look at the horizontal stabilizer all stripped clean of film covering. (We’ll forget about the elevator for now.) To get that right…to represent a plywood-skinned surface…I could cut it all off and start over, insert/recess the outer edges of every rib as well as the outer faces of the top and bottom spars and “inlay” a new sheet covering the way I did on the wing, or smooth off the existing surface and skin over it. If I did THAT with 1/64” plywood the extra thickness of the completed structure would be inconsequential, the “scale” appearance of the model would be acceptable, and that’s what I did.
Last week I promised you for an interview with one of the test pilots of the Esky D700 3D 6ch Heli. It took a little bit longer than I would have liked due to our busy schedules, so I apologize for that. But without further adieu, here is the interview with sponsored test pilot Antonio!
Hello Antonio. Thanks for taking the time to talk with me today. Lets start with an introduction. Why don’t you introduce yourself to our readers.
Sure, it’ll be my pleasure. I’ve been driving and flying RCs for about nine years now. It all started in middle school for me when I bought an RC car off a friend. Played with and of course modified it myself and soon after I found myself into RC helis and planes as well. Been flying ever since. I’ve worked with NitroPlanes and HobbyPartz for about two years. I love the fact that I get to do what I do for a living, testing, building, and promoting RCs all day long. I love the industry and I love the job…it’s very fun.
So let’s talk about the D700 3D by Esky. What were your first impressions when you saw this thing out of the box? Anything in particular that popped out at you or peaked your interest?
The first thing I noticed was the new style of the body; the colors too. The green on black is very nice and definitely caught my attention from an aesthetic point of view. Once I started flying it, the gyros immediately caught my attention. I was prepared for the compensation I was going to have to do base on experience with the Belt CP, but it wasn’t needed at all. Esky really improved upon the gryos for the D700. The radio feels great too. It feels better than some after-market radios out there, not some cheap stock radio. I’ve flow with JR and Spectrum and can tell you this radio Esky provides is up there with them. They use the same programming and everything too.
Browsing through the Nitroplanes FB fans page as well as some RC forums, I’ve noticed that some users disagree with you. They feel that the radio is a bit tacky. Anything you’d like to comment on that?
I would actually disagree with them. I mean, people are going to have their own opinion and obviously there will always be people who hate certain designs and layouts, but as a person in the industry, I felt Esky took a big step forward in this radio. Like I said, the programming is really similar to other top brands so it’s easy to get used to. It overall is just a radio I would use any day. No need to replace with some other transmitter really unless it’s a brand preference thing. And in that case, it’d just be personal choice…nothing wrong or tacky with the radio at all.
As you and most people who’ve been following Esky already know, the D700 series is a successor to the Belt CP. How would you compare the two? Let’s talk technical.
Like I said before, it really is a big step forward. One of the main things I noticed once I started flying is the way the tail holds. Compared to the Belt CP, the tail stability is much higher. It just feels like there’s an expensive gyro in there. Not what I expected at all from a stock gyro. It holds position well in hover, rotations, etc. The weighted tail blades in back add to that stability. I think Esky hit their mark in the improvement they wanted in the D700.
Now, the D700 3D is a 6ch heli capable of 3D flight. What about how well the Heli handles tricks?
The D700 3D being a flybar system, the heli flies pretty well in 3D. I’m used to a flybarless system as I fly flybarless helis for fun and competition personally most of the time. Back to the D700, the servos have enough torque to handle most 3D maneuvers. There are some advanced maneuvers that I could do that would cause the servos to stall out, but it isn’t necessarily a bad think like some would think. If you’re a beginner to intermediate flier you’ll almost never stall them out. Especially if you’re just starting to do 3D, the stock parts on the D700 are perfect. No worries, everything is centered well and handles great without much need to trim on the fly a lot.
Is there anything on the D700 that you would like to have been different? Any improvments you wish Esky put that wasn’t included?
Like I said before, the servos can stall out on extreme maneuvers (under torqued if you will) for my style of flying. But there’s a ton of servos you can buy, not only on HobbyPartz, but other manufacturers as well if you really want to push this heli to the limits. The tail servo is fine once gain set is right on the radio. I would definitely keep the stock gyro. So yeah, pretty much just switch out the servo if you want to push the limits of the heli.
Any upgrade recommendations out there for those who like to spend time modifying their RCs?
First thing I would recommend (as you probably guessed already) is carbon fiber blades. You wouldn’t believe the difference it makes. If you really want to do extreme maneuvers, like extreme extreme maneuvers, then get some upgraded servos. Solar 9g digital micro servos work perfectly. Otherwise, everything stock is fine if you’re a beginner to intermediate 6ch or 3D flyer.
Any final thoughts?
Hmm. Not really haha. I think I pretty much covered everything I’d like to say. The D700 flies great. It handles well and is pretty stable with the stock gyros. The radio is excellent. I think I’m just repeating myself. Haha. Oh yeah, I guess one last thing is, I hope this heli isn’t the first one you own, because it is not for beginner fliers. When I said beginner earlier, I meant 6ch beginners. But as long as your skill level is ready for 6ch flight, this heli is perfect. Definitely give it a try out. And if you have your own flybarless system and prefer flybarless, there’s also the D700 3G version. It’s the same heli (with some slight performance versus stability tradeoffs) but flybarless.
You can find the original review on the Esky D700 3D 6ch Helicopter here: http://blog.enhobby.com/2012/07/esky-d700-3d-6ch-heli-review/
You can find the Esky D700 3D 6ch Helicopter here: http://www.xheli.com/eskyheli-003738-d700-3d-rtf-24g.html
Pilots’ Upgrades Recommendations:
Any 315mm-335mm Carbon Fiber Blades
9g Micro Servos by Solar
Alternate servos – spectrum & align 9g micro servos
Gens Ace 11.1v 2200mah 60C Battery
Yes its very nearly time for IPMS at Telford. Once again ADH publishing will be attending and have a staging area for demonstrations and features throughout the show.
One of the exhibitors Deluxe Materials will be giving a demonstration on their products.
Create & Shape
As well as chosing the right glues
We will also have demonstrations from Precision Ice and Snow as well as many ADH contributors.
We look forward to seeing you once again for the 2013 show.