mred33

I love hinge points. I have been using them since they came out and will never go back. Love the drilling jig too. I use Gorilla Glue on mine and if you wype the foam off if any comes out while it is still soft, it is easy to clean the hinge points off. I have also had the same problem with using control horns on balsa, but I started using the type you are using through a peice of plywood that I put in the balsa just like you do and they work great. You can also shave a little balsa off both sides and epoxy 1/16" playwood in there and that works good for mounting the regular kind, but I use a bolt and nut on it and CA the nut so they don't come off. The build is looking great. Keep up the good work.
Ed

CrateCruncher

My Feedback: (1)

Right Ulf, the elevator halves were sanded down to 1/8" at the trailing edge. Ed, I love hinge points too but haven't tried foaming glues yet. Here is a pic of the wing. Look at all these ribs! The Pica version only has 10 per side, the MK 2 has 12. Everything fits great so far but I need to replace a couple of 1/4" sticks- too soft. I'm currently working on the reinforcements for the landing gear and nacelles. I'm leaning toward 1/16" ply to reinforce the ribs in these areas. I also am planning air lines for the retracts and servo extension routes through the wing.

ulfenator

Mike, are you building the whole wing in one piece or one half at a time?

I was planing on using spruce in stead of balsa for my wing spars, it might make it a little bit heavier but it will be stronger.

Ulf

mred33

Gorilla glue is GREAT for hinge points. Take a peice of 3/8" balsa and drill a hole in it and then install a hinge point. After the gule sets, try and pull it out. If you ever try that, you will see why I use that glue for the points. It works great. Just make sure you clean the foam off the hinge line when it is soft as that is much easire then doing it after it sets up, but it's still not that hard. No where near as hard to clean up as epoxy is or even yellow glue, but the hinge points will never come out unless you rip something apart. Once they are in, they are there to stay. Try it once and you may never go back to the other glues. Doing great on the build also. Keep up the good work.
Ed

CrateCruncher

My Feedback: (1)

Well, I was going to build this wing in left and right halves, sheet them, then glue them together at the root as is customary.

I understand low-wing planes need some dihedral to offset their slight roll-instability but how much is enough and where does it begin to fight roll inputs from the pilot? I plan to knife-edge this plane and want it roll-neutral. I want some dihedral in the wing but think 4 degrees as designed is a bit excessive.


Looking back on one of my favorite planes of all time, the Bridi Kaos, I've noticed that with 2 degrees of dihedral the natural taper of the wing from root to tip makes the top surface flat! Just the surface I happen to have on my building board...

After giving it some thought I've come to think the easiest, strongest, and most accurate way to build this wing is full span, upside down.

CrateCruncher

My Feedback: (1)

I've been working on the Duelist off and on now for the last week. The easy part is always ordering parts and supplies. Tower came through with the Robart retracts I wanted. They are Part #521W1 ti-gear with 3/16" mains and 5/32" nose gear. The nose gear mounts to the firewall on this set. Using my postal scale I estimate they will add 12 ounces over fixed gear.

I'm not crazy about the multiple piece fabricated canopy on the plan so I also bought a Great Planes P-51 Mustang replacement canopy #GPMQ2290 that looks like it was made for the Duelist MK2. I forget who mentioned this canopy in a previous Duelist thread but they were spot-on.

The build has slowed down a bit because of the wing. I take pride in not worrying over the little stuff that doesn't matter. However, the wing being straight matters. After jacking with this one panel for a week I finally have it in a straight enough alignment I feel I can begin to glue. Why so long? Well, the ribs are drawn in groups, odds and evens. When laid out on the plan the odds are 1/16" shorter than the even numbered ribs in front and evens are too short in back. Shims - next. The wing panels are 1/4" difference in length. OK, reposition the last rib so they match - next. The leading edges bowed when I cut them from a straight piece of sheet stock. Replace the wood - next. The rib leading edges and trailing edges don't align. Average them and sand/shim the outliers - next......You can see from this paragraph I've gotten a taste of Murphy's law this last week and it sure is frustrating.[:@]

ulfenator

>>You can see from this paragraph I've gotten a taste of Murphy's law this last week and it sure is frustrating.>>
Yes, that is why we call it modeling......

Thanks for the information about the canopy, I didn't care for the looks of the original canopy on the plans either.

I got a sneaky suspicion about the ribs on my plans, when I was tracing them out and cutting the rib temlates the countor of the ribs at the main spar doesn't quite lign up right on some ribs, I think when I copied the plans it possibly got distorted a little bit.
I have already made my ribs out of 1/8" balsa so I'm sure I'm going to have the same problem as you with the ribs being short also.

I have an old set of Rohm Air Retracts that has never been used, my air lines crumbled that is how old they are, I'm hoping to be able to use these in my Duelist, just need to order new air lines. The nose gear I have is also a firewall mount.

Thanks
Ulf

P.S. I'm hoping in about 2 to 3 weeks to start building my Duelist....

CrateCruncher

My Feedback: (1)

Good to hear you'll be starting your Duelist soon Ulf. It goes without saying but, post pics whenever you want. I'd like this to be more an exchange than a book report...

I forgot to mention, I drilled 3/4" holes in the center of ribs 2 through 6 about 1/2" behind the main spars for air and electric lines. You can see them in the last post. I plan to locate my aileron servo between rib 6 and 7. I also added 1/16" ply to ribs 3,4, and 5 for landing gear mount and nacelle reinforcement. Wing skins were completed a short time ago and came out nice.

All in all it's been a fun build and the dramatic styling of the plane are already starting to take shape.

ulfenator

Mike,
Is there a place here on RCU where I can learn how to post pictures, also what is the desireable size of picture to upload.

Thanks
Ulf

CrateCruncher

My Feedback: (1)

Here ya go:[link]http://www.rcuniverse.com/forum/m_5218588/tm.htm[/link]

ulfenator

Perfect, just what I need....

Thanks

Michaelj2k

Here's an interesting variation of the Duelist. http://elliotfan.com/art/flight/me246/246_img_01.htm

CrateCruncher

My Feedback: (1)

One down, one to go! I reinforced the leading edge with some scrap triangle stock, made a guide tube from rolled paper, and added additional 1/4" stock scraps to the trailing edge for the point hinges to bite into. I was going to build the entire wing t the same time but there was really no advantage to doing it that way and I figured sheeting would be easier one panel at a time.

TCBLightning

My Feedback: (5)

Nice work so far...I usually don't cruise the kit forum and was surprised to see this here.

My Duellist MKII is pictured below. It is my second, the first was from the Pica kit. I modified the tail but the rest is per plans. Running TT Pro 46s and mechanical retracts.

It isn't the fastest plane at the field but does awesome flat spins

Keep up the great work.

ulfenator

TCBLightning,

That is a very nice Dauellist, love the color scheme.......

Question for you about the flat spins, I have heard that it can be very dificult to get out of a flat spin and end up crashing......

How do you get it into a flat spin and also how do you recover from one????




Michaelj2k,

Thanks for the information and pictures...

CrateCruncher

My Feedback: (1)

Nice looking Duelist TCB! Thanks for sharing. Yes , this project is a bit of an oddball here in the kit forum. I started it in the scratch forum but the place was like a morgue. We Duelist enthusiasts are tolerated here, for now. Tell us a bit more about your airplane..

TCBLightning

My Feedback: (5)

I have found that recovery is easier on full tanks (10 oz). Control input is typical flat spin. At a reasonable altitude just zero the controls, push down a little and a blip on the throttle and she pulls right out.

One time I entered the spin about 2/3 or later into the flight and the recovery was a bit scarey. It didn't want to stop spinning and took a little more push and throttle to regain control and damn near required a post flight trip to the port-a-potty. It is my assumption that the low tanks changed the CG enough to make the difference. Whether that is the case or not, all my flat spins are done on the first half of the tank.

The covering is ultracote metalic purple and pearl yellow. The pictures kinda make it look blue. I used the GP P-51 canopy as well.

TCBLightning

My Feedback: (5)

I was reading through the thread about joining the wing halves. Mine was built per the plans including the dihedral. I did use about 8" of 2 oz. fiberglass cloth across the middle just to make sure it will stay together, although Dave Platt says it is not needed per the article that accompanies the plans.

On the vertical stab I started out with one that was much smaller but lost almost 4" in fuse length and was concerned about how that would impact stability based on some feedback from a forum member [link=http://www.rcuniverse.com/forum/m_3840197/anchors_3840197/mpage_1/key_vertical%252Cstab%252Cdesign/anchor/tm.htm#3840197]in this post[/link]. If I were to build it again I think I would use my original design because it looks better and I have a ton of rudder authority on this bird.


BTW, check out page 116 of the March 2008 Model Aviation.

CrateCruncher

My Feedback: (1)

Interesting discussion TCB, thanks for the link. You are unique in that you've had a chance to live with both the standard tail and modified so an actual comparison can be made. How does the fin/rudder mod knife compared to stock? Does the forward-slanted hinge line produce any unwanted pitch-up with extreme rudder?

I also wanted to ask about your intermediate shaft for your dual elevator pushrods. That looks really clever and although my plane is now past the committed stage, I would love to hear the details.

Did you notice drafting inaccuracy in your plans. My port wing is 1/4" shorter than starboard! When I flip a tracing of a supposedly symmetrical rib over and try to line it up on the original its NOT symmetrical.

And the million dollar question; Having built TWO Duelists what other things did you do different on the second one and what would you do different if you built a third?

ulfenator

Tim,
Thanks for the information and the link...

I'm also intrested in the questions Mike brought up...


This is great, love all the information you guys have, it is going to make my build so much easier with all the pictures and information.


Thanks again
Ulf

TCBLightning

My Feedback: (5)

As far as performance differences in the two tail configurations there was quit a lag in between flying the different models for me to give an honest comparison. My first Duellist had about 20 flights on it and because of the short legs on the Pica version I was having prop issues on the paved runway I flew at in San Antonio. I bounced on take off and broke a prop completely off leaving the spinner turning and some crazy RPM. In the process of going around to land I tried to kill the screaming motor, lost too much air speed and stalled and crashed (March 2005). I was able to salvage the wing and rebuild the fuse with the MK II plans and lenghten the mains which was needed after the move to WI and now flying off a grass field.

I totally dumb-thumed Duellist 1.5 after the rebuild and about 20ish flights in 2005. I came across the field inverted rolled upright, was going to roll back inverted and push out but got distracted by conversation in the pitts and pushed before I rolled and plugged it straight into the ground.

On the knife-edge I honestly can't remember what the tendency is, I haven't flown since last fall.

For the elevator connection I have a Sullivan carbon fiber pushrod connecting to a Central Hobbies dual elevator control mechanism with a Hitec 5645MG servo. I originally had a Futaba 3010 in there but experienced some flutter and stripped the gear. I landed with about half the cogs stripped and was very lucky. I tightened up the connections at the control horns as much as I could and have not experienced the flutter since. Either the servo is handling it or taking the slop out did the trick.

I spend way too much time trying to get my nacelles centered before I took a ruler and measured each wing panel to discover the inacuracy. I was relieved to discover that it was an error in the plan and not sloppy building on my part.

When I built the first Duellist I had a bow in the fuse when I sheeted the sides, not much but it was noticable on the building board. I left it and didn't notice any wierdness in flight and I adjusted the incidence as required. I have planked the top half of the two subsequent fuselages. Not sure what I did wrong on the first but that was my fix. All the incidence are set at zero for the MK II so nothing to change there.

Other than changing the tail because it looks cool I didn't feel the need to really change anything. The wingspan on the Pica kit was 67" and the MK II is 69". I would consider chopping an inch off each wing of my current bird if it would give me more speed.

vicman

My Feedback: (10)

The Big D has long been on my list of planes to "one day" build and must say I really like your color scheme and tail layout.

Nice job sir.

CrateCruncher

My Feedback: (1)

Great details Tim. Thanks for taking the time to recount some of those painful memories. I have other planes I can use that dual elevator control on.

I've always wanted to have a crack at a Duelist ever since I saw one hanging in a friends dorm room 20 years ago. It's kind of a hot rod pattern plane anyway so its not like anybody will get bent if you modify it. Given how much Platt was into scale at the time he created the Duelist it may have been an urge to go wild.

Mike

CrateCruncher

My Feedback: (1)

Progress continues at der Duelist Werks. I got the starboard wing panel framed up last night and had to balance everything together to make it look like an airplane. I also couldn't resist making propeller noises as I imagined it slicing through the sky.

I offset most of the ribs slightly on the plan so the panel would match the length of the first panel. I would have used the other side of the wing on the plan but wanted to build each half of the wing upside down so I could position all the ribs vertically with a triangle.

The next step is massaging the individual ribs to conform to the average airfoil which should be fun. Then I'll sheet the top side of each wing, then glue the panels together upside down and flat on the board. Before sheeting the bottom of the wing I plan to align it with the fuselage and drill the holes for the leading edge dowels and wing bolts. Then the retracts and bottom sheeting go on.

ulfenator

Tim, thanks for the information...

Mike, your project is moving right along, looks good !!!

Would you say that building the wing upside down is the way to go?

Mike, when you built the fuselage did you install the air tank for the retracts already?

Ulf