kargo

With the tank floor/battery floor part of the hatch made I used the fuse as a template to cut out the bottom sheeting for the hatch. The stock model has you sheet over the bottom part of the fuselage, so this was cosmetically a natural fit. I cut the sheeting a little larger than was necessary and later sanded it to fit. I made a cutout to avoid covering the hatch latch, and also had to reglue the edge of the sheeting after it broke near the cutout. I then used epoxy to sandwich the nylon hinges between the bottom sheeting piece and the tankfloor/battery floor hatch piece. Because the nylon hinges pivot point rested just outside the F1, landing gear block and balsa sandwich, the hatch fit flush with the bottom of the airplane when closed. Again, the pictures will tell the story.

traxxaspede

looks nice, i was actualy thinking of getting an electic schoolyard acro cub by HOB, im guessing the design pretty similar to this, and it looks great.

kargo

On to sheeting the cowl...

The electric conversions I've seen of this airplane all sheet over the cowl "cheeks" for a better look. I did the same. On mine I made a mock oil filter to provide an air inlet. Look at decathlon pictures on the internet and you'll see this just below the prop. I also put air inlets either side of the prop, similar to the ones on a scale decathlon.

Cowl face
I re-installed the motor, tightening it down one last time. I then made the face of the cowl out of ply. There was a fair amount of measuring where the prop shaft would exit. I made the air inlets either side of the prop with a spade bit and a exacto knife to square the inner sides of it. I held the cowl face in place by giving it tabs to run screws through. I placed the tabs, glued on edge, on the inside of the cowl face so that they fit flat against the inside of the cheeks. I then drilled the screw holes, threaded them, and used CA to harden the threads. Although I don't have a picture of the inside of the cowl face and its tabs, the one of the screws on the outside of the cowl should make it clear as mud. Having the face installed with screws and not glue will allow me access to the motor. I'll have to cut away the covering as it was covered with the cowl face installed, but I don't intend to access the brushless motor unless it needs to be replaced.

Sheeting
I made a single piece of sheeting just a little larger than needed so it could be trimmed/sanded to fit. I cut out the oil cooler air inlet before giving the sheeting a curve. I used medium CA, not gluing the sheeting to the cowl face. I later had to add more CA to the edges of the cheeks/sheeting, as they separated some after sanding.

Oil cooler air inlet
The stock model makes wheel pants by sandwiching oval shaped pieces of balsa together, and then sanding to shape. These balsa pieces are progressively smaller, so the sanding goes easily. I did the same for the raised edge of the air inlet. I used CA glue them on, as they too had to be curved. I built it out so much that I later had to sand it back to get enough clearance for the prop.

kargo

thanks traxxaspede, we're still waiting to do a maiden. weather isn't cooperating so here I am doing the build thread instead...

arniebud

Hey Kargo, what the update on this project? Still working on it , complete, or flying it? I have been interested in adding this plane as my next, wondered how it flys.

kargo

Arniebud and Gang at RCU,

Yes the project is finished, unfortunately I have not taken the time to finish the build thread. Life is simply very busy and I wind up devoting my time away from family and work to finishing the decathlon and other projects. Bit off a bit more than I could chew I guess I'd like to finish the thread someday, and rebuild the wing I totaled by flying it into a pole The wing build shouldn't be to big a deal, the first one went very quickly. While not a beginners kit like the Sig LT40, it does build very easily. The biggest problems I had was making the wingtips look nice and the electric mod. HOB has the same kit, the AcroCub, setup as an electric (motor suggestions, the whole works)

Unfortunately, especially with the way I powered it, flying this model was a little beyond my skill level. I had my friend and instructor maiden it. It was tail heavy and we wound up crashing into some weeds. I would HIGHLY suggest using the HOB recommended balancing procedure of an eye-screw at the CG. "A nose heavy airplane fly's poorly, a tail heavy airplane fly's once." Words to live by. I rebalanced it and made the repairs, but the flying season was over. Towards the end of the winter I couldn't stand it anymore and took it out (by myself) to the fairgrounds behind our house. I handlaunched it and promptly smoked a 9inch light pole. Don't misunderstand me, the HOB Decathlon IS A GOOD FLYER (via ALL the reports I've read, and based on its tailheavy flight survival), its just got a bit too much snap for me to handle just yet . Everyone said it was a lot of fun to fly. After we get our Kadet Senior and Four Star 40 done, and fly them and a PZ Trojan (currently in a tree) a season or too we will build a new wing and flyer' again. I'd highly recommend this airplane for the intermediate pilot, as a second kit.

If anyone has any questions for this enthusiastic amateur, I'll do my best to answer them. Thanks for everyone's help, including Sharkflyer on Wattflyer.com.

kargo

Some Pictures;

kargo

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kargo

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kargo

The pole totalled the wing, but the fuse and fins escaped with only a few scrapes. I used Nelson Litefilm for the covering, which is a tad more touchy than ultracoat (etc) but doable. I used plastic sheeting to make templates for the star pattern, and a sheet of glass and windex to make clean cuts. I also used windex to position the star cutouts on the covered wing/fins. I squeegeed out the air bubbles with a piece of balsa scrap. Let it dry overnight and iron the next day. The color/hue of the white litefilm is much different when using this method as compared to ironing it on straight away.

later

NorfolkSouthern

I just maidened my House Of Balsa Decathlon 10 earlier today. The takeoff was slow, with only 30 feet or so required to get airborne. I trimmed the elevator down slightly, and added perhaps one or two clicks of left aileron to achieve hands-off flight. It flew perfectly with the OS 10LA engine, and no structural issues were noted even with a sustained flight at full throttle. Wind conditions were a little bumpy, and thus some work was required to keep the wings level. Coordinated turns were no issue, and it performed snaps very well with good recovery. Inverted flight required little elevator correction and turns were smooth. When I ran out of fuel during my last flight of the day, a long glide ratio was evident and resulted in smooth landing with a slight bounce. The wheels are a bit small so they snag easily on grass. As expected, I did experience a nose-over in that case but there were no scratches.

The instructions in this kit assume that the builder has some experience, so some of the details are left out. A small example: it is assumed that the builder knows how to shape the leading edge at the wing tip, and also how to build a receiver mount and route the antenna. The radio equipment layout required the most thought for me, and I had to build the hatch over the fuel tank from scratch. I decided against building the wheel pants, as the needed tires would have been too big anyway. They assemble by sandwiching several pieces dye-cut parts together and then sanding the part smooth. The finished weight of this project came in at just over 2 pounds, with perhaps an ounce or two added for good measure.

Overall, the durability is good and the flight characteristics are excellent. If you have an OS 10LA or 10FP that needs a home, this Decathlon is definitely worth considering!


NorfolkSouthern

NorfolkSouthern

Here are a couple photos, one of the receiver and servo layout, the other is of the engine. The throttle is controlled by a cable, rather than the standard push rod seen on most Great Planes or Hangar-9 ARFs and kits. Soldering this part and attaching the ball link proved to be one of the most challenging parts of the build, at least in my opinion.

NorfolkSouthern

kargo

sharp HOBD! Mine is still on the shelf, another "on-going" project. I think the last one simply had cg issues, and that my thumbs were not up to the task yet. Hopefully I can build another wing this winter, after the hog bipe and 4star 40, not to mention the magnetic building board...

Thanks for adding a review of your maiden. Its nice to know there is hope for mine...

NorfolkSouthern

Thanks, Kargo. The main rule with this plane, is this: Make NO modifications to the CG. Follow the plans to the letter when balancing! It should be just forward of the center main spar. Some folks may consider this to be a little nose heavy. But trust me, it works. When getting this bird off the ground, the left wing may drop a bit. Don't panic! Just give it some rudder and a little throttle. It'll be up before you know it. Then, throttle down once you reach the desired altitude. I would also practice coordinated turns at high altitudes, to study its flight characteristics with as much detail as possible.

During one of my flights, with the wind at my tail, I cut the throttle and then banked right. This caused my left wing to stall, and a spin resulted. With the plane spinning to the left, I just allowed it to build some speed and applied a little right rudder instinctively, where the rudder application probably wasn't even needed. I then just added some up elevator and throttle to climb out. I have flown other planes that would snap more viciously and take longer to recover, so this wasn't bad at all. Just don't try this stunt with a CAP!

Why not get the wings fixed, and slap some skis on that critter? You could fly it during Winter when you want some stick time, while keeping the Four-Star and Hog as Winter projects. Why not?

NorfolkSouthern

kargo

I agree 110% with your cg recomendation. We fingure tip balanced this one at the field, it wound up tail heavy and VERY squirly. I'm glad I had my buddy flying it, I probably would have rekited it after we got it into that spin... I couldn't add full power without it wanting to pitch up a lot, which I assume is related to the aft cg. Did yours have any full power pitch up tendancey, or do you have a theory here? I wound up adding some lead to the front, a lot in fact. It balanced better, but the rest is history I guess. I'm going to make some modifications in the fuse to get a lipo past/under the firewall to help bring the cg forward. That or use two stubby ones in parallel. It was a long process to cover the wing with the starburst scheme and the nelson light film, but I think I'll do it again. It just looks too cool. Maybe I'll get it going for the winter, it would be way cool on skis. Just have to buy another kit...

NorfolkSouthern

Mine will also pitch up a lot at full throttle. I trimmed down a bit on the elevator for that reason, and usually control the altitude with the throttle and the speed with the elevator. Everything turned out to be spot on after that. Mine was also fingertip balanced, and some lead was added to the front but not much because of the weight of the engine.

I think you really should fix what you can of that wing if possible. Or, you can buy another kit if you feel it can't be fixed. You already have the fuselage done, and that's most of the work. You could probably have it back up and running before the snow flies.

The HOB Decathlon has to be one of the most under-rated kits on the market. I'll be sure and add what ever tips I can when I start compiling my report.

NorfolkSouthern

kargo

Thanks for taking the time to send the pm. If you wouldn't mind, I'd like to pick your brain some more...

The HOBD is kinda where I learned the hard way what you are talking about, although I think it being a tad tail heavy and it being a tad over powered probably contributed to things... I'll have to put a smaller prop on that electric motor. It was my fault in any case. Since then Cody and I finished a Sig Senior and have flown it, flown the lt40 we did two winters ago a bunch, and flown a parkzone trojan over the last flying season. I know my skills have improved much, that being said they are probably just good enough to let me get into the trouble you describe with the two sig kits. Particularly the hogbipe.

In your opinion, is this little decathlon a friendlier airplane than the 4 star? After my experience with it last winter, I thought the opposite were true. It certainly is an airobatic wing (i.e. not a trainer). I sure like the t28, but maybe it is too forgiving or too light an airplane to prepare me for the two sigs. The one thing that really concerns me with the decathlon is the pitchup tendancy at full power. It was really bad when it was tail heavy, it made it very difficult to fly. I assume it'll get much better when it is properly balanced. Would mixing in some down elevator at full power detract from the skills I'd build on this machine?

You mentioned using the power for altitude and elevator for airspeed. Its a bit counter-intuitive (kinda like my spelling), but I think its what you are talking about when you say "flying the wing." It behaves differently at slow speeds vs fast. Slow you may need more power to climb instead of a higher pitch, which might cause you to loose altitude. At high speeds adding more power will increase speed, and pitch controls the altitude. Does this sound like what you are talking about?

I'm definetly going to build another wing, I just need to order the kit. The spar was pretty smashed up, so I think repairing it could just lead to further spectacular events. It should be a lot of fun on the skis. The pictures below are of the Kadet Senior that took Cody and I forever for to build. Another winter project is for me to tear off the wing covering and replace the leds. The middle row didn't even work, don't know what I did wrong... We didn't fly it at night as the gang and I decided it wasn't set up well enough to provide enough orientation/visibility. I'll get bigger leds for the wing, and try to get more red and green light on the tips. I don't know why I thought leds and night flight would be a good idea on a red and black airplane.

As for the snow flying, I'm too late for that. We got about 1/2 inch last night in WI, and its still falling. Hopefully it'll melt when it warms up a bit next week.

NorfolkSouthern

The Hog Bipe will have more drag than the LT, and thus a shorter glide ratio. However, it does not have the pitch sensitivity that a Decathlon has, nor does it have the close rudder coupling. But, just because the Hog Bipe may be a little easier to fly doesn't make it more durable than the Decathlon. And this is where people get themselves into trouble. If you rotate the Hog Bipe too soon and tip stall on takeoff, it will suffer significant damage, or maybe even a re-kitting. But more than likely, the HOB Decathlon is durable enough to where it will have little or no damage. You can compensate for the error and keep flying for the day.

Not necessarily friendlier. It will require a bit more finesse during takeoff, and of course it will also require a more concentration and control inputs. While the Decathlon will likely drop a wing if it gets too slow, the Four-Star will be less likely to. But, bad things do happen to good people. And that's why I spent $40.00 in extra covering and materials, plus a couple weeks time and labor, to fix the wing to my low-wing trainer. With the Decathlon, you get the opportunity to practice more stall recoveries as you build on your flying skills. This may help you save a more expensive model one day. The one bad takeoff I did with my Decathlon resulted in no added expense. Instead, I got more practice with a slightly more challenging airframe, to better prepare me for what I may face with the Cox Giles G-202 I'm putting together as of this writing. I can always fix my HOB Decathlon, but they are no longer making parts for the Giles.

In a way, yes. Pitch is especially important in maintaining airspeed should an engine go out. The elevator has that down in spades. Down means faster, up means slower. Just the right amount of down elevator will increase your airspeed and give the control surfaces more pressure, for better control. Too much up, and the lost pressure will result in decreased control with an increased angle of attack, which will cause the plane to no longer be flying. The first component that loses lift first will fall first. That's is what a tip-stall is, in a nutshell. When you fly on the wing, you get better at minimizing that risk.

A metal pole is a lot harder than balsa and Monokote, yes indeed it is. Especially when you lose an argument at cruising speed! But most mishaps happen during takeoffs and landings. I think you'll appreciate the durability of the wing and fuselage more as you spend time with it to improve your motor coordination at the controls. Then, should you lose trim on the Hog Bipe or end up with a deadstick on rotation with your Four-Star, you'll know exactly what to do to minimize the likelihood of a crash, because it will be ingrained by your experience flying the Decathlon this Winter. Unlike others who have just finished building a kit, you won't be sweating with nerves twitching nearly as much this Spring when you do your maidens. And that, sire, is priceless.

NorfolkSouthern

kargo

Not sweating with nerves when I maiden the sigs, yes that WOULD be priceless. Thank you again for taking the time, your advice is awesome. It'll feel really awesome after a narrow miss...

Its intersting you said most accidenets occur on t/o and landing. T/O is when the decathlon/pole conversation happened. A hand launch, it veared towards the pole and I pretty much froze. It couldn't have hit it better than if it'd been on rails. I am glad I haven't had that experience with a more expensive model. I think you're right, it may be a bit more challenging to fly, but it will be a lot better (and cheaper) education than other models, particularly the trojan. You almoust don't land that thing as much as you find a spot for it to stop flying. Ever see an old movie clip of a biplane landing on an ship modefied into an aircraft carrier? Thats the t28 on grass.

Please post some pictures of you winter project along the way. I think we'd all be interested in seeing it.

Kargo

rich52mag

Hi

I see you have built the Cox G-202 and was wondering if you know where the CG is located.
I have one and I'm replacing the engine but don't have the manual any more.
Thanks for any help, Rich

kargo

sorry, i haven't built anything from cox sir