Well I've been having a blast with my "plane #3" (see the end of the "It ain't pretty but..." thread), and am making a new version to address some of it's shortcomings. All the over-all dimensions are the same, but the new one will have a symmetrical KF airfoil (and generally stronger wing), a rudder, and better landing gear. The wing is complete and the fuselage is getting there:
As for the wing, I've been fooling around with some mild aerobatics, including inverted flying, and the first version is doing some rather alarming wing flexing in stuff like this. The new one should be quite a bit stiffer, and maybe preform better inverted. I dunno...
The addition of a rudder will hopefully make it so I can maneuver around on the ground some, and should also help with doing rolls.
I'm getting sick and tired of nosing over upon landing, so the new one has the main wheels way out front, and only as long as necessary to keep a 9" prop out of the grass. I'm also going to make it so the tail skid pivots, like a caster (ground handling, again).
If this thing works as well as I hope it will, I may even give it a name
Your plane is looking great use some Square hollow carbon fiber stock for the wing brace, depending on the wing thickness, i use 6mm to 10mm SQ CF tube, the Square CF will brace your wing to take wing loads of over 10 Gs, in the build below, I used a Slow Stick fuselage to brace the wing with, after the 6mm cf tube was bending a little after some flights, i added the SS fuselage, problem solved
the blue plane below has a Slow Stick fuselage for a wing brace, it does not bend at all the wing is made from 9mm depron
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I wanted a stronger KFm airfoil, but I did not want to go the CF or spruce route so I brought the center piece of foam forward to within one inch of the leading edge of the wing. The center foam-board doesn't really add much strength, what it does do is it keeps the outer leading edge foam-board from buckling under load.
I built 3 Dollar Tree foam-board flying wings which I hope to do a thread on soon.
Just need to do the rudder & elevator linkages. Looks like the weather will be good Monday, so I'm hoping for the maiden flight then.
By the way, I discovered something NOT to do with this one: Before putting the colored tape on the wing I thought I'd put some waterborne polyurethane on the trailing edge & ailerons, thinking it might stiffen them somewhat. It may have done that, but the tape doesn't stick to it very well . So the covering on the ailerons is kinda baggy. I think they will work OK, but it ain't a good thing.
Well the maiden flight(s) were a complete success! Flies like a champ and it can be taxied around on the ground (although I need more practice in the taxi on the ground thing ). Flew through 8 batteries with no crashes or nose-overs upon landing. Many inside and outside loops, lots of rolls (kinda ugly rolls - need more practice with that too). It's fun to fly! I had another club member (much more advanced than I) fly it and he liked it too. I'm pretty darn pleased, if you hadn't noticed .
There is hat-cam video, but it sucks, so I'm not posting any of it.
It flies! The lack of any dihedral and the low wing configuration make it a little "twitchy", but it's not too difficult to control... Need to pay attention though, that's for sure.
The weight of these planes keeps creeping up, and this 3rd (and heaviest) monoplane version obviously suffers from it. This one really needs a 3 cell battery to make it fun to fly... It flies OK on 2 cells, but it's not very lively. The first one weighs 11.55 oz, the second 12.85 oz, and this one 13.5 oz as flown today. (I've since removed pilot Mickey, which takes it down to an even 13 oz). The biplane version, at 15.4 oz (and lots more drag from struts), will just barely get off the ground on a 2 cell battery, but does pretty well on 3 cells. I'm learning
Very Nice Build Dave Put Mickey Back in the plane and use a 3 cell lipo, 2 cells dont work very well in most planes unless you have a high kv motor, Dont worry to much about the weight of the plane, you need a little plane weight to help the plane with momentum to get the plane through any stunts and wind, a little weight is your friend to much weight is not your friend Take care and have fun, Chellie
I may be getting Older, But I Refuse to grow Up I am Having to much Fun to Grow Up LOL
Don't worry, Mickey will fly again! Although Marvin the Martian is next in the rotation, I'm thinking .
Yesterday I took the new plane, and the first version (the one at the end of this thread: http://www.wattflyer.com/forums/show...t=67824&page=2 ), out for comparison. The new one wins on ground handling & structural strength in the air (no wing flexing detected), but the old one is more stable, able to fly nicely on less power, and generally more enjoyable to fly. The old one just jumps off the ground on a 2 cell battery, the new one struggles to get up in the air on 2 cells. (The both have the same motor and prop, by the way.)
So I'm going to do another combining the best elements of each .
It's going to be high wing like the first, which I think adds some stability (weight hanging below the wing...). I'm going to do a non-symmetrical KF airfoil like the first, which I think probably gives more lift, and certainly presents a thinner leading edge - less drag. The wing will have a carbon fiber spar - I've got some square 4mm tube on order from BP Hobbies (thanks for the link, Chellie!). Same steerable tailskid and forward-placed main gear.
In addition to those things: full length ailerons, and wider ailerons and elevator (probably 1 1/2" instead of 1").
I think I might really have a nice plane after all this.
And here we go! My carbon fiber stuff arrived today so I've started on the wing. First I milled a 6061 aluminum center section for the 4mm CF spar, with 4 degrees of dihedral (about 1" at one tip of the 40" span) and epoxied and thread-wrapped the two sections of the spar to it. Here it is in place:
The wing on version 1 has a "ramp" after the "bump", but it's formed only by the packing tape covering spanning the gap, and it's un-even. So on this one I put in a tapered foam piece which the tape covering will be solidly adhered to:
Took it out this morning for the maiden, and 9 other ~6 minute flights! 32 degrees and spots of snow on the ground here and there, but pretty much no wind . Flies great! On a 3 cell battery it has enough power to do nice big inside or outside loops from level flight. On 2 cells it flies just fine - gotta dive a bit to do a loop, but it's no slug - takes off and climbs out with authority. Flies inverted just fine with the asymmetrical wing, and it's got excellent ground handling. Definitely my new favorite plane!
I wasn't going to make another of these, but.... .
The last one is a lot of fun to fly, but it lacks aileron authority. I'd like to be able to do nice snap rolls, and it just can't do it. (Contrary to what I said above, I did not make them wider, which was a mistake, I think.) So this new one has 1 1/2" wide, full length ailerons.
It turns out that the earlier versions have a somewhat weak aft fuselage. In a hard, nose-in crash they bend and kink a little behind the wing. So this one has balsa longerons in all four corners of the box-section fuselage. It's a lot stronger.
More power! The old ones all have cheap hobby king 1550 kv "donkey" motors*, which delivered about 14.5 oz of thrust with an 8 x 3.8 prop. For the new one I've got a HURC "power up 400 sport" http://www.headsuprc.com/servlet/the...0-Sport/Detail which should be a big upgrade . The bigger motor alone adds an ounce to the weight... that plus the balsa reinforcements, I'm guessing we'll be at about 14-15 oz without battery, around 18 oz AUW. Should have considerably more thrust than weight .
Also put on a tail wheel instead of just a skid - I'm curious how much difference that makes in ground handling.
Airframe is pretty much done, need to do linkages, electrics, etc.
(* those "donkey" motors work great for a while, but the bronze bushings just don't last very long. One season, tops..., then there is no easy way to replace the bushings. Once again, you get what you pay for.)