SMALL - SMALL - Telemetry SMALL - Radio
fhpe77's blog
Posted by fhpe77 | Mar 24, 2015 @ 12:45 AM | 1,808 Views
I got the receiver mounted on a nice platform made from 1/16" plywood and supported by 1/8" balsa sheet. The receiver is simply secured to the platform with Velcro. The antennas were oriented in the correct relationship, 90 degrees apart, and the ends were sleeved in some scrap push rod tubing. I decided to go with a small, two bay hatch. Care was taken to insure that all of the electronic components will be accessible from this hatch since the forward fuselage will be entirely sheeted in 1/16" balsa. The hatch opening was flanged with to 1/16" x 1/16" balsa. The hatch itself is made from a cross-grain lamination of 1/8" balsa sheet on top of 1/16" balsa sheet. The resulting part was thicker than needed and was sanded to follow the contour of the fuselage. The hatch is secured with a 1/16" plywood "tongue" at the front. A 1/8" balsa tab with T-nut was added to the fuselage which allows the rear of the hatch to be secured with a 2-56 socket head screw.
Posted by fhpe77 | Mar 21, 2015 @ 11:18 AM | 1,161 Views
Now the fun part. Solving the equipment mass, volume, and placement problem is my favorite challenge. My design priorities are usability, durability, and that specific order. Model airplanes should be easy to get into the air once you arrive at he field. They should be built light enough to be competitive in their class but they need to be able to withstand the occasional hard landing. You also have to be able to service it. Servos occasionally need replacement. You might want to swap a receiver. Easy battery replacement is a must if you fly electric power. To compound matters, I like my old-timers to be field convertible from piston engine to electric motor. This allows me to fly in two contest classes, in the case of this particular airplane, 1/2 A Texaco and Electric LMR. Plus it will allow me to fly at the local schoolyard with quiet electric power so as to not disturb the neighbors. That sounds all well and good, but the finished airplane has to balance at the correct point in order to fly properly. I like to build the fuselage, tail, and wing before I even start to explore the balance. These parts are assembled and the balanced is checked. Of course the whole mess is extremely tail heavy because there is no engine yet. That's when I start to shove weighs in the nose. I have various sizes of lipo batteries on hand so I use them as weights. Once I get it to balance I weigh the ballast on a small postage scale to see what I have to...Continue Reading
Posted by fhpe77 | Mar 02, 2015 @ 07:22 PM | 1,569 Views
Who knew that gluing some wing sections together would have been so involved? It also helps if your plans have the correct dimensions. So I started constructing the sections in accordance with the dimensions shown on the plan. I thought I'd be slick and build the correct half angles into each section so they'd go together perfectly. After completing the wing center sections and the left wing tip it started to become apparent that something was wrong. The tip angle appeared to be too extreme. After much debate and analysis it was looking like the wing angles were not scaled properly, if at all. I confirmed this by emailing Jim O'Reilly, the guy that drew and scaled these particular plans. It turns out that he missed scaling these dimensions and thus they were greater than they needed to be. Fortunately I was able to modify the left wing tip for the correct angle and construct the right wing tip so it was correct from the start.

The next hurdle was the wing joiners. The laser cut ones provided in the kit did not match the plans and would not contact the upper and lower spars equally. I simply cut some new ones from 1/16" plywood that matched the plans.

From here it was pretty much straight forward. I joined the wing sections with 30 minute epoxy, using various sizes of binder clips as clamps. Plywood and balsa scraps were used to spread the clamping load in some critical areas.

I'm also not real happy with laser cut fuselage forward bulkhead and firewall. They seem a bit small. I've started the re-engineering process by measuring my fuselage and drawing it in CAD. From here I plan to generate some 1:1 scale paper templates that can be easily transferred to some plywood. I'm still working this out so we'll see...
Posted by fhpe77 | Feb 15, 2015 @ 09:04 PM | 2,876 Views
Wing construction commenced this past week. I was able to pretty much complete the left wing by working on it a couple of hours each evening. A little more sanding is needed but it's close to the final shape. Since the kit contained extra ribs, I decided to close out each panel. Simply butting the panels together with 30 minutes epoxy slathered on each end rib results in some serious gluing surface. Clamp them together and once cured, they will be bonded forever.
Posted by fhpe77 | Feb 05, 2015 @ 11:22 PM | 3,046 Views
The short kit provided some nice laser cut mounting tabs for the horizontal stabilizer. This was certainly a job for 30 minute epoxy. So I get out my epoxy and start thinking "I've had this for a while, I wonder if it has a shelf life?". And there it was on the package: Use by 11/17/12. As I pondered the stressful drive to the hobby shop after work in rush hour traffic it occurred to me maybe I should mix up a test batch of the old stuff to see if it cures. Success! The next morning my test batch was rock hard. So the following evening it's game on and I managed to get the tabs glued on. 1/16" balsa was used to fill in between the tabs and yet another piece of 1/16" balsa was laminated on top. Some careful sanding resulted in a nice mounting surface for the tail feathers. Drilling mounting holes in the horizontal stab's plywood hard points required some thought. I was able to transfer the hole location from the fuselage's mounting tabs to the bottom of the stab with a pencil. This was only after carefully aligning and securing the horizontal stab to the fuselage with some painter's tape. The holes had to be drilled from the bottom of the stab which required the fabrication of the drilling jig that supports the stab by it's four hard points. This worked out really well. The holes were located nearly perfectly and were slightly corrected with a round needle file. I pressed four 2-56 T-nuts into the stab's new holes and permanently secured them with medium CA. The T-nuts extend through the stab approximately 3/32" and project into the fuselage mounting tabs which does a great job of locking in the stab.
Posted by fhpe77 | Feb 01, 2015 @ 10:47 AM | 2,431 Views
I spent some time this weekend completing the elevator. The resulting parts are very light weight. Great care will be necessary during covering. I imagine that standard weight covering will have the potential to warp the elevator. To avoid this, the decision has been made to cover this airplane with Solite. I've had great results with Solite in the past. Solite will shrink and tighten up nicely but it remains slightly elastic so covered parts will not warp. The drawback to using Solite is that the parts must be constructed to be very straight in the first place because you won't really be able to "shrink out" any warps. Parts weights are:

Vertical Stab/Rudder = 3 g
Horizontal Stab/Elevator = 10 g
Fuselage/Pylon = 30 g

Grand Total = 43 g or 1.52 oz

It's going to be interesting to see just how close I can get to the SAM minimum allowable weight of 16 oz.
Posted by fhpe77 | Jan 26, 2015 @ 05:22 PM | 2,767 Views
While I did complete the Crack Yak at the end of August, my latest build is still in progress. I don't know if anyone actually reads my blog, but way back in 2011 I built a 1/2A Texaco Simplex. It was flown in one contest for a 2nd place finish but was lost a couple of weeks later due to a structural failure of the wing. This airplane can be seen here:

Now it's time for some payback! This next airplane will be lighter and better performing. Bob Holman Plans supplied the Jim O'Reilly plan which was beautifully drawn in CAD, in 2010. Bob Holman also supplied a laser-cut short kit, which is good for me as I do not enjoy cutting ribs. Jim's O'Reilly's plan is scaled down even further than the 1983 Jim Reynolds plan that was published in Model Builder magazine. The O'Reilly plan shows a 47" wingspan and 288 in^2 wing area. SAM rules allow minimum wing loading of 8 oz/ft^2 for 1/2A Texaco. Doing the math, my minimum weight is just 16 oz.

National Balsa supplied the various sticks and sheets needed to complete this plane. What a great company to deal with. They actually gave me more pieces than I had ordered so I would have more pieces to choose from. I will be purchasing from them again for future builds.

Finally, like my previous old timer builds, this one is getting the dual power setup. Of course the first one will consist of a Cox .049 Babe Bee engine. The other power plant will be some sort of...Continue Reading
Posted by fhpe77 | Jan 25, 2015 @ 06:38 PM | 2,438 Views
Wow, my last post was over a year ago. What can I say? I'm a bad blogger. You know how it is, life takes over, less time for hobbies, etc. I used my free time to actually fly. It was all about the ALES contests for 2014. For now I'm back to building so I want to share my latest exploits.

At the insistence of my friend Bob, who happens to be an expert 3D pilot, I purchased a Twisted Hobbies Crack Yak-55 kit. 3D is not really my thing but I am interested in improving my skills. From what I've read, this is THE 3D EPP plane to have. With Bob's generous assistance, I was assured success. Bob's first advice was to go for a 3-cell setup. The increase in power allows this plane to perform well outdoors. Which is good because I don't really have the confidence to try flying it indoors. Bob also suggested going with some robust digital servos. I got to fly one of his Crack Yaks that has the standard servos form Twisted Hobbies and it flies great, but when you try one with digital servos it's a whole new world. Here's my equipment list:

Motor: Motrolfly DM2205
Propeller: APC 8 X 3.8 SF
ESC: Castle Talon 15
Battery: Turnigy Nano-Tech 460mAh 25-40C 3-cell
Elevator & Rudder Servos: JR DS188
Aileron Servo: JR DS290G
Receiver: Airtronics RX700 (had it laying around, will be replaced with an RX500)

The kit came double boxed and was in perfect condition when it arrived at my doorstep. I have to say, this kit was really well done. It came with...Continue Reading
Posted by fhpe77 | Nov 16, 2013 @ 11:14 PM | 6,705 Views
Last weekend I managed to forget to snap a picture of my Fireworks 5. I like to take a picture of new planes just before the maiden flight just in case it all goes wrong and it gets totaled. So I went out today for my second session and managed to snap the attached picture. It was cold, damp, and overcast today. Not too much in the way of lift going on. I had one 4 minute flight but that bubble petered out quickly. It was, however, time well spent. I got to tweak the radio programming a little, adding some more down elevator to landing mode. Expo was added to the elevator and ailerons in thermal and cruise modes as I forgot to do this during the initial programming. I also wanted to run the battery down and see how much time I can get out of it. After an hour and a half the Turnigy Nano 300mAh, 35-70C 2-cell battery was at 7.4V. Pretty impressive for such a small battery. The last throw of the day is where it got interesting. I threw it hard and upon release I heard a cracking sound. In a state of panic I make a quick transition to level flight then brought it back for a landing. Initially the wing was suspect but then I observed the forward wing mounting nutsert was partially pulled out of the fuselage. Good grief! I thought this thing was supposed to be strong. The nutsert was pressed back in to it's original location and thin CA was wicked in around it. It now appears to be solid as a rock. We'll just see about that tomorrow morning when I head back to the field for another session.
Posted by fhpe77 | Nov 09, 2013 @ 09:08 PM | 4,726 Views
The light at the end of the tunnel was shining brightly yesterday. With 4-6 mph winds in the forecast for Saturday morning, I was busting to get the Fireworks 5 ready. It was a throwing blade, balancing, and radio programming away from being flown. So I was on a mission starting on Friday morning to get it finished and flown.

I carefully milled a slot in the left wingtip with a tiny Dremel ball mill. A combination of measuring and marking coupled with expert eyeballing resulted in a well located throwing blade. Once the blade was oriented in accordance with the instructions, top forward when viewed from the side and leading edge cambered toward the fuselage when viewed from above, a couple of drops of thin CA were used to lock it into place. The throwing blade has an airfoil shape and does not fill the entire slot. The resulting voids need to be filled and a fillet is required between both upper and lower blade to wing surface interfaces. My old friend Devcon 30 minute epoxy to the rescue! To achieve proper fillet shape retention while curing, I added enough West System 406 colloidal silica to create a medium-thick slurry of goo that was subsequently directed into the voids with a tooth pick. The tooth pick was used again to build up and shape the fillet on each side of the wingtip.

As built, it weighs in at 258g. An additional 10g was needed to get it to balance between 65 and 70mm from the leading edge of the wing. For the mathematically challenged, this...Continue Reading
Posted by fhpe77 | Nov 09, 2013 @ 06:27 PM | 4,595 Views
Non adjustable control rods...ACK! What a foreign concept. I'm a Dubro EZ connector kind of guy. Since I never tried this sort of thing before I was kinda looking forward to it. It actually worked out quite well. I built the aileron lever ends first, installed them, then measured and cut the carbon tube at the servo horn end. With the radio fired up and the servos centered I glued in the L-bends, resulting in a perfectly sized custom control rod. While the instructions called for thin CA, I opted for medium CA for the extra (read not instant) cure time. The keeper wire is 0.028" and is held to the carbon control rod with heat shrink tubing and backed up with thin CA.

Hmm, a rudder pull-spring. Yet another new technique. Per the instructions, I bent the spring wire so the span was 25mm and the legs were 15mm. It was easy to poke the wire spring into the balsa stab and rudder. Finally, the spring was secured with some thin CA, which also served to harden the insertion points.

The tail to fuselage interface was secured with thin CA and backed up with some carbon tow and more thin CA. This has effectively made the fuselage and tail one piece.

Kevlar wire was used for the elevator and rudder pulls. This stuff can be twisted and glued with thin CA or knotted and CA'd. I used all the above techniques to secure the Kevlar wire. Silicon grease was applied to any sections of the wire if they were at risk of being accidentally bonded with CA.
Posted by fhpe77 | Nov 04, 2013 @ 07:03 PM | 4,729 Views
Ten pounds of stuff in a five pound bag. That's what it was like getting the electronics into that fuselage. It took me a couple of evenings of scheming, test fitting, and massaging until I determined the best layout. Excess wire was eliminated by modifying the length of the servo wires. Mounting the regulator in the rear leaves plenty of room for the battery in the nose and allows it to be easily removed for charging. This position also allows the regulator's voltage indicator light to be visible through the canopy. The inside of the fuselage was lightly scuffed with some 150 grit sandpaper and with the servos already attached, the radio board was glued in with medium CA. I didn't trust myself with epoxy around those servos. That was a mess waiting to happen.

Thanks to A Main Hobbies, I was able to source the elusive UHU Por conact adhesive necessary for hinging the rudder. That stuff was hard to find, what is it made out of unicorn tears or something? Per the instructions, some UHU Por was spread on the rudder and v-stab and allowed to set up for 20 minutes. Two small pieces of scotch tape were applied to lock in the correct position of the rudder then the entire hinge line was covered with a ten inch piece of scotch tape. Finally the rudder was notched out and the kit supplied control horn was glued in with medium CA. Please note that my plane is being set up for a right handed thrower. The launch peg will be installed in the left wingtip the tape hinge is on the left side of the rudder, and the rudder horn is on the right side. Lefty configuration would be just the opposite of this.
Posted by fhpe77 | Oct 14, 2013 @ 08:56 PM | 5,334 Views
My son managed to shoot some videos of my Gambler AG. The first is two launches were in dead air. Those flights weren't too long. The second video shows the Gambler AG in a light thermal. That flight was around three minutes but the video didn't start recording until I was in it for a minute or so.

Two Short Gambler AG Flights (1 min 50 sec)

...Continue Reading
Posted by fhpe77 | Oct 14, 2013 @ 08:48 PM | 5,333 Views
Here's what I have for electronics. The battery is a Turnigy nano-tech 2S, 300mAh. The regulator appears to be a PLD-BAC-55C which has both visual and audio battery status indicators. The original owner provided the recommended servos. Hitec HS-45HB's for the ailerons and elevator and a Dymond D4.7 for the rudder. According to the rcgroups thread for this model, the HS-45HB may have some issues with the elevator return spring. Feeling the tension of the spring with my hands, I have to agree. So I replaced the elevator servo with a Hyperion DS-09SCD. It's taller than the HS-45HB and will require some care in placement and horn length to get it to fit and not rub the hatch. The receiver is an Airtronics RX-500. It's perfect for this application because I have exactly five things to plug into it. There is no way it will fit with the case so I removed it and gave it the heat shrink treatment. The hole in the heat shrink is for access to the bind button and status LED. It is taking some time getting all this stuff to fit into the fuselage but in the end I expect the same level of serviceability that I demand from all of my airplanes. It's not worth a hill of beans if servos can't be easily swapped.
Posted by fhpe77 | Oct 14, 2013 @ 08:19 PM | 5,465 Views
Just about a year ago I folded the foam core/bagged wing of my competition style DLG for the second time. I imagine it could be repaired again at the cost or even more weight. The day of it's last flight it was tipping the scales at just under 12 ounces. That's just too darn heavy. It was given to me because it was old and outdated, but the donor was certain that it would be good for me to learn how to setup and fly four servo DLG's. He was right. I loved that thing. I flew it for about a year and a half and got pretty good at it.

Upon it's demise I started looking at what it would cost to replace it with a modern design. One of the models I looked at was the PCM Fireworks 5 Flow. It looked to be a pretty innovative design with outstanding performance potential. Then I looked at the price. Way out of my budget! It was getting to the point that I was considering one of the Chinese knock-offs but I just couldn't bring myself to do that. So I figured that I would just build me a Gambler AG and be happy with that. And I am happy with Gambler but it does have some limitations.

One day last month, at the South Jersey Golden Eagles club field, there was a gentleman that was asking some of the other sailplane pilots if they'd be interested in a DLG kit that he was looking to sell. He was pointed in my direction a proceeded to make me a offer I couldn't refuse. He had a Fireworks 5 Flow kit for sale, including servos, battery, and regulator. The price was, well lets just say it was really, really good. Apparently he had injured his throwing elbow at work and didn't want to aggravate it by throwing a DLG. He was simply looking to get back some of the money he spent on it so he could invest in a less physically demanding model. His loss was my gain. For once I was in the right place at the right time. I never thought I'd be able to own this level of model and I'm still waiting to wake up and find out it was a dream.
Posted by fhpe77 | Oct 02, 2013 @ 09:41 PM | 5,262 Views
I wound up with a slightly tail heavy airplane, which was to be expected with the light weight battery. In order to get it to balance at 3/8" behind the spar I needed to add 0.35 ounces to the nose. I simply taped a nickle and a penny to the battery which got the balance perfect. This brought the AUW from 6.15oz to 6.5oz.

The maiden flight was performed last Friday evening and consisted of a gentle toss into the 5mph wind. A couple of clicks elevator and rudder trim got it flying straight. The next toss was a gentle discus launch. Subsequent launches increased in force but the gambler could take it. Very impressive for such a light weight airplane. I was easily hitting 70 - 80 feet launches after a while. I also noticed that a 6.5 ounce DLG does not beat up your body as much as an 11 ounce competition style ship. I flew for 45 minutes until sunset and the battery came down at 8.1V. It looks like up to two hours of fun are possible.

The evening maiden was nice but lift was scarce. So I went out at 1:30PM on Sunday afternoon which was gloriously 75 deg. F with 6 mph winds. There were tons of low level cumulus clouds, indicating a nice thermal day. I wasn't disappointed. The Gambler was spec'd out repeatedly for an hour before I decided to call it quits.

In conclusion, I highly recommend this airplane. The build was quick (for me) and reasonably challenging. Flight performance is excellent for what it is and the Gambler will stay aloft for quite a while bouncing from bubble to bubble. Put this thing into a moderate thermal and it climbs like mad! Good stuff.
Posted by fhpe77 | Oct 02, 2013 @ 09:11 PM | 5,358 Views
Dymond D47, 4.7g servos were chosen for this application. They've proven themselves to me in the Wind Dancer V-tail. Torque output is outstanding for such a small servo, centering is good, and the gear slop is tolerable.

I deviated from the servo mounting technique outlined in Allan's great instructions. I just can't bring myself to glue servos in with CA. Also, horizontal mounting would make the Dubro EZ connector set screws inaccessible. Thinking outside the box, I chose an inverted vertical mounting scheme. The servos are screwed to balsa mounting blocks. An additional benefit to the mounting scheme is that the push rods no longer have to make any radical turns to meet the servo horns. This reduces the load on the servos and extends battery life.

The battery is a 30g Rhino 360mAh, two cell lipo. It fits with plenty of room. The voltage is reduced to 5V with a tiny 1A Blue Arrow linear regulator. I've used this configuration is four servo DLG and would regularly get nearly an hour of flying out of it.

The receiver is an Airtronics RX-600 that I had laying around from my now deceased molded DLG. The regulator is simply stuck to the top of the receiver with double sided tape.
Posted by fhpe77 | Oct 02, 2013 @ 08:45 PM | 5,289 Views
Wing covering consists of more white Solite and yet another appearance of transparent blue Solite. I know what you're thinking. "Didn't this guy learn his lesson when he covered his Wind Dancer with white and light blue?" Well the answer to that is apparently no. Actually I had the covering left over from the Wind Dancer. It's already paid for, so why not use it. The color scheme is not that bad. I just have to be on top of my game if the plane starts to spec out. Certain angles and lighting conditions can make it disappear.
Posted by fhpe77 | Oct 02, 2013 @ 08:37 PM | 5,287 Views
Carbon tow was laminated to the tail components. I opted for some additional reinforcement as the increase in stiffness seems to offset the minor weight gain. For the sake of durability, some tow was added to the lower leading edge of the vertical stabilizer. That seems to harden it up nicely.

I chose to cover these parts with white Solite prior to gluing them to the boom. This just seemed to make the most sense. The control surfaces where hinged with scotch tape. In order to shape the balsa horizontal stabilizer pylon mount to conform to the boom, sand paper was taped to the boom and it was used as sanding bar. This resulted in the correct concave shape. Note that I managed to not take a picture of the pylon...doh! Prior to gluing, the covering was cut away where the Kevlar reinforcements attach.