Thanks, Theecoop. Nearly a hundred views and yours is the only comment At this point I am pondering whether the drag/anti-drag struts in front are sufficient and whether or not to add additional fuselage bracing members. I plan to use the same lift struts used in the Himax, though the lengths will be slightly different the strut attachments and carry-though will be identical. I'm also hoping I can get in the thing without cutting a door. Won't know for sure until the wings are mounted.
Bob is this going to be a Bi plane or are you just raising the standard wings? Hard to comment without understanding what you are doing. Only thought is you might want to tie down to the bottom longerons too, lift from the bottom not just the top kind of thing.
Randy, the idea is to raise the standard wings to a parasol configuration. I'll pin the wing spar brackets with AN4 bolts to the channel brackets bolted onto the square aluminum root tube as shown in the third group of pics. You can see that the front pair of these brackets are mounted toward the top of the root tube while the rear pair are mounted toward the bottom. This sets the wing incidence angle. The lift struts will attach to the fuselage with a bracket bolted near the top of the gear leg just like the Himax. As for tying into the lower longerons, that is what I attempted to do as shown in the rear brace pic in the second post. Because my ply fuselage sides bow in about a half inch as is typical, adding a vertical member under the foreward angle bracket might be a problem. The plywood in that area has been increased in thickness to 7/8" and the reinforcement plates butt against the top longeron to resist tension in the foreward antidrag strut. I suppose I could add an anti-drag bracing wire pair if the strut is insufficient. The middle angle bracket is mounted through the vertical member which I reinforced with a couple of short 3/4" square wood pieces. Now, if you have a pair of wings to donate, I would love a biplane
The alum. stock looks to be sharp edged 90degree that does not like stress. It should be of a rounded style witch I dont know its proper name. For safety sake look into it with someone knows the different types of stock. Was just wandering why you are changing the design.
Chris, If you're refering to the aluminum angles shown in the frontanglebracket titled pic, there is a radius on the inside of the 90 deg. angle. The aluminum channel, however, doesn't have a large radius, true. It seems the radiused channel stock in the dimensions I needed is rare, couldn't find it on the Aircraft Spruce, Wicks or other web sites. I suppose I could use steel or pairs of radiused angle.
I chose to try the parasol configuration because I always liked the look of the type, like to look down while flying, like to look at the wing in relation to the horizon for judging level flight attitude and was disatisfied with the fit of the spar/strut attachments, the wings would not go on without alot of swearing
Bob, I applaud your boldness. That's why it's called experimental. But you ARE basically designing a new airplane, especially if you're not using engineering calculations, and are relying on eyeballing things and using logic as your design tools. As the man said..."be careful out there."
Bill, Yes, you're right. I hope to preserve the geometry of the Himax spar-strut system and my purpose for posting the pictures is mainly so any Himax builders here will say either "looks about right" or "whoa, not even close". I've also tried to get info on other parasols like the Loelhe Sport Parasol and the Texas Parasol and see what their cabane structure looks like. I believe my efforts so far are very robust. This is also the Bernie Pietenpol method of airplane design. We can debate the quality of his designs. I admit I'm relying in part in the forgiveness offered by a low weight budget, takeoff weight should be well under 450lbs.
A brilliant inspiration!After all ,every high wing is a parasol if you remove the glazing. I would ask for a little more.Can we get rid of the good but labour intensive minimax wing and replace it with an alum tube spar wing which can be built in a day or two. I have noted that the cabane load which I assume would be considerable is being taken by the threads of the bolt you are using to tie the u bracket to the L shaped piece below.Why not a long u channel bolted to the vertical between top and bottom longerons .The cabane strut can then be bolted to the channel in shear. Keep up the good work.Wish u a safe test flight.
I hope I am wrong about this but I see what could be a big problem. I will try to explain. You need some thing on each one of the upright "v's" to keep them from twisting up and down as the airplane turns. When you turn one side of the (inverted) v will try to raise and the other side will try to lower. You have four pive t points with nothing to keep the uprights from twisting side to side.
Thanks for your encouragement and enthusiasm! Part of my problem is working with existing wings! But they are already built so I'll use them. You're idea of using a channel piece is interesting and could no doubt be made to work. It would likely be stronger. Why didn't I do something similar? Because I didn't think of it! The bolts in tension holding the u-channel brackets at the lower ends of the cabane struts are 1/4" (AN4) bolts as are the bolts holding the root tube to the u-channel where the cabanes meet. The weak link here is the aluminum u-channel bracket. I may replace those with a stronger aluminum channel or use steel.
Dave,
I think I understand what you're getting at. The root tube could have a torque put on it by a side gust of wind let's say that lifts one wing or in banking the wings with aileron as you suggested. I demonstrated this to myself when I dis-assembled the wing after rigging. I lifted the wind tip during the procedure and the root tube rotated just as you suspected. The lift struts weren't attached at this point. I don't think the torque would have been as severe had the lift struts been in place, most of the lift would be reacted by the lift struts. I will do some analysis and calculations to determine what's going on. My first thought is to rivet a large gusset where the cabane struts meet.
Hi Bob; I think what Dave is saying is something that was corrected on the Airbike. If you should suddenly kick in rudder, the wing will want to stay as it was. The fuselage will be turning, but the wing will lag and twist the fuselage between the forward and rear cabane struts. On the Airbike, I believe they have a drag cable to correct this on each wing heading to the rear for attachment. This prevents the twisting loads on the fuselage and cabanes. Bob
Bob, Thanks, I've been wondering what the purpose of that brace wire on the Airbike was all about. I wonder if the narrowness of the fuselage, particularly where the rear cabanes attach, is the cause. If so, the reaction you describe should be less of an issue for my airplane. Still, I am contemplating adding brace wires, probably leading from the lower longeron under the engine to the front strut/spar attach point.
What I believe Dave is talking about is the possiblility of rotation of the root tube along its longtudonal axis in relation to the cabane/u-channel attachment. This stems from the unequal compressive force applied at the spar root fittings and the (presently)free rotation of the u-channel fitting around the bolt at the cabane strut end. I propose to resist this with a large 1/8" thick gusset like so:
Hey Bob; Gotcha, Dave has a good point there. I misunderstood that one. Drag wires would not hurt you a bit. On the Himax, there is still some flexability there, but the structure carries it OK. You can always add the drag wires later if you see any movement there. Sorry I misunderstood your concern Dave. Bob
regarding this parasol, I would see another possible MiniMax look a like layout, to squeeze it down to the Aeromax width with a sit on top layout.
Those guys having issues to squeeze them into a parasol MiniMax would get an important improvement to entry their bird.
Further the easy plans built possibility would remain, as no complex laser cut items would be required, but could be added to speed up the building process.
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At this point I am pondering whether the drag/anti-drag struts in front are sufficient and whether or not to add additional fuselage bracing members. I plan to use the same lift struts used in the Himax, though the lengths will be slightly different the strut attachments and carry-though will be identical. I'm also hoping I can get in the thing without cutting a door. Won't know for sure until the wings are mounted.
