jeffp51

More pics. the interplane struts have been glued together, lightened, and sanded to airfoil shape. then it was time for the turtle decking. One end of the two hatches (one for the fuel tank and the other for the radio/servo compartment) are held down with magnets from a defunct brushless motor. The other end is held in place with a pin latch constructed from pen springs and pushrod wire. Sorry for some of the repeated pictures, but I can only see where to upload pictures, not where to remove them. does that delete link delete individual pictures, or the entire post?

jeffp51

I have been working on hinging and lightening the tail of the plane, since it looks like it will likely be tail heavy. I have managed to shave a couple of ounces off, which may also help me keep the overall weight under 7 lbs. the servo hatch/ cockpit and the turtle deck are now done, although my son thinks I should sheet the rear turtle deck too.

balsa brain

This is a really nice build you have going on Jeff. Thanks for sharing. Subscribed.

Bill

wildwillie3

I agree,

Bill

jeffp51

Thank you. I am enjoying building the plane, but as an original design, I worry about how well it will fly. There are so many unknownsare the angles right? do I have enough down thrust? do I have enough power? will the engine even run? All I can do now is cross my fingers and keep building.

balsa brain

I am having to post using my phone which is a pain but how is your build coming? I have one design-build but not a bipe and no swept wings. Seventy eight inch span with a converted 31cc Ryobi. Both the plane and the engine conversion were firsts for me. It has not been flown yet and I can't find the memory stick with the pics. Sorry for the rambling, lol. I will post more when I can get on a computer.

Bill

balsa brain

BTW, I for one am following your build with a great deal of interest.

Thanks again,

Bill

jeffp51

Bill,

Progress has slowed a little because I had to start teaching class again. That and I am a little stuck on the the cowl. Stayed up way too late last night trying to work it out. There are some complex curves and tight spaces that have to be accounted for. I also realized that my CG calculations were way off when I was first designingwhich was good, since the previously calculated CG would have left the plane very tail heavy. After double checking my numbers using several different methods, I realize that the CG should be further back than I thought, which puts me in a much better situationI shouldn't have to add any lead, which I always hate.

I would love to see some pictures of your project. It sounds interesting

jeffp51

More pictures. I have finished the cowl. It is a clamshell style, split horizontally, with both sides removable so that I can access the engine. I use the masking tape to protect the parts I don't want to sand down. I really hope balsa dust is not carcinogenic.

On the advice of my oldest son, I also sheeted the rear turtle deck. It is only 1/32" thick, so it will be delicate, but the 1/8 balsa longerons were also really soft, so it won't be any worse.

jeffp51

On the tail you can also see the fairings over the fin and stab. They are also hollowed out behind to reduce weight. the bottom of the lower wing has also received a fairing to blend it in with the belly of the fuse.

jeffp51

Here we see the mounting of the top wing center section and the cabane struts. I borrowed an incidence meter for this one. Normally I am good with leveling the fuse and measuring the LE and TE of the wing to get it right, but aligning the top and bottom wings with 1 degree of decalage wasn't possible without a meter. Everything is glued in with epoxy and held with clamps until it sets. I also chose to cover the underside of the top wing center before attaching it, since it would be hard to do afterward. It feels good to start the covering process, and have some color on the plane. I like the contrast of the dark blue and the yellow.

jeffp51

Covering continues slowly. I started on the wing struts, but ran into trouble because they are plywood and have a lot of compound concave curves on it. The covering did not want to stick to the edges at all. I had to rip off my first attempt and start over by covering the edges first and then the sides. The final result is adequate, if not particularly remarkable. Some people just seem to have a talent for covering, and the rest of us just muddle through the best we can. I would like to sit and watch someone cover who is really really good some day.

The pilot is also now installed in the cockpit. I found the bear at a garage sale. He is old and ratty, and has lots of character. He also now has a wooden stick up his neck. My son enjoyed watching me cut his legs off. The cockpit lining is split fuel tubing. If I can find a workable material, I may also add some leather stitching to hold it on.

jeffp51

Having trouble getting on to the site. my virus protection software is blocking the site from homeFrom work, no problem. anyone know how to solve the problem?

update on the plane: I covered the rudder and the other wing strut, but work has put a real cramp into my building timethat and I helped my son put together his foamie nerf-trainer I never had anything like that to learn on.

jeffp51

Here are some new pictures. Work is still getting me down, but at least I am back on the forum. The checks are sealed together on a glass plate first and then attached to the wing. the top of the bottom wing is also covered. I am having a hard time finding an extended period of time to do the big chunks. It could be a while.

jeffp51

More extremely slow progress. covered some bare spots on the ailerons, and added the starburst stripes. Not shown in these photos, I have also glued in the fairings between stab and fin. Next week I am in Colorado, but after that big project is done, I should have a little more time for building.

jeffp51

Endlich! Some progress on covering the upper wing. I realized after I had the right half covered that I didn't seal the end of the wing tube sleeve, so that the wing tube was free to slide out the end and become unbalanced. I glued a piece of balsa over the end of the left half, and as long as I attach that side first, the tube should stay centered. Next up are the stripes and then some body work, and then I will cover the fuse. Pictures aren't loading at the moment, but I will get them up soon

jeffp51

New stripes for the top wing and covering on the cowel. The compound curves on the nose were trickier than I thought. The next step is fuelproofing the cowel interior, the tank compartment and the forward hatch. It seems like I am getting close to finishing, but I keep thinking of little things that need doing. Switches, fueling probes, hinge gap sealing, engine break in. . . I also pinned the cabane struts with carbon fiber pins. I like things to be physically connected beyond just a glue joint. Even though the surface area is pretty high, my thinking is that the pins will add shear strength. Maybe it is over-engineering, maybe it won't help any, but it doesn't ad any weight, and I feel better about it.

I had hoped to fly the plane by the fall, but now it probably won't happen that soon. I am running out of good days to fly. I started the design process almost a year ago now.

balsa brain

May I ask what are carbon fiber pins and where did you find the ones you used? They sound like a good ideal to pin things during builds like hinges. BTW, your bipe is looking real good!

Bill

jeffp51

I will post a picture of it next time I do an update. I used a 1/16" (probably 2mm really) carbon fiber rod and cut it into 1/4" pieces. then I drilled though the struts in the wing center section and on the fuse, and glued the reinforcements in with thin CA.

And thanks for the compliments. I look forward to all types of feedback, although I can't change much on it now.

jeffp51

I fuelproofed the cowl and tank compartment today with 30-minute epoxy thinned down with alcohol. Also included here are pictures of the pinning process. There is a plywood plate in the center wing section that overlaps the back of the N-strut. The three pins create a physical tie between the strut, the backplate, and the rib. For the pins I used the CF rod pictured, cut down to just over 1/4-inch. Next up is more covering, but I will be in since I will be in Philly for a week, it will take a while.

jeffp51

Here are some pictures of the covering process, which is nearly complete now. Just some final assembly and balancing left

jeffp51

and a few more. I am thinking about adding a stripe along the side as well. Not sure yet.

jeffp51

I have been putting the final touches (in between finals and grading) on the biplane. The last real construction is the wheel pants. I built them as a clam shell, with 1/64" ply in the center to help keep the shape I wanted. Each half is 5 layers of 1/8" balsa and one 1/16" layer on the outside to blend in the ply mounting plate. Once the basic shape was formed, I rough-cut the airfoil shape, and then began sandingusing a sanding block on the outside and a dremel tool on the inside. Overall wall thickness is about 1/8"-3/16", although there are a couple of spots where you might be able to see a little light shining through. Total weight for both is just a hair over one ounce.

I wonder how many people in the world truly understand the pleasure of working a piece of balsa with sanding block and paper, smoothing everything slowly until everything is perfect. It gives you the chance to meditate, and contemplate just how good life is when you can take a little time to make something with your own hands just the way you want it. I probably could have bought some wheel pants somewhere, but I could have bough a whole plane somewhere too, and this was far more satisfying. Friends in my club were giving me a hard time that I hadn't grown my own balsa trees for this one.

jeffp51

And here are some pictures of the nearly finished airplane with the pants covered and mounted. Last Christmas this whole project was still in the CAD program, but I am happy so far with how it has turned out. I hope it flies. I will post video if it does, and probably if it doesn't. I still have a few minor bits and pieces to complete, and I need to break in the engine enough that I trust it not to die at the wrong moment. I also will have to wait now for some good, warmer weather to fly in. Final weight is about an ounce over 8 pounds. The wing area is 930 sq. in, give or take, and the wing loading comes out to just under 20 oz/sq. ft. I am not sure yet how much throw to put in the control surfaces, but I will likely program in some exponential, and make sure there is more up than down on the ailerons. there is a degree or two of down thrust, I forget now exactly how much, and the top wing is set at one degree positive decalage compared to the bottom. The bottom wing and the horizontal stab are set at 0 degrees to the center line.

There have been over 3000 views now, and I would appreciate some feedback, good or bad, on what people think, or opinions on how you think it will fly.

Thanks for reading

PatternPilot

My Feedback: (58)

Nice looking plane..what is the weight ? some of the areas looked heavy with ply...