bradleyban

I have recently purchased a NIB Dave Patrick Ultimate ARF. I have spent a couple of days now assembling the plane and when I got to the fitting of the wings i have an issue with the top wing. The first thing I noticed was that the interplane struts were jarred one way. So i thought that there was a twist in the wing. But apon further investigation there was no twist in the wing at all. What I did was removed the bolts from the center cabane and the wing sat nicely ontop of the interplane stuts and was sitting about 1/4" back of the center cabane. The center cabane does not look like its supposed to be adjustable but I may be able to adjust the position of it.

One thing I'm confused about adjusting the cabane is that the CG is related to the center cabane so I have no idea if I'm going to be throwing something way out of proportion

I have only read good things about this plane and can only think that I have got something backwards or there is an easy fix for this. I wish I could get ahold of Dave Patrick himself and ask him some questions about my situatuion.

Here are some pictures of what I got

K-Bob

My Feedback: (1)

I believe you have the interplane struts backwards or flipped. Attach the center cabane screws first then install the interplane struts. I don't have my DP Ultimate handy to check or I would.

bradleyban

Hey Bob

I have tried flipping the interplane stuts every which way and they only seem to fit one way. It's good to know that you still have yours. It would be nice to compare some measurements with someone else to see if they are the same.

I don't believe that this planes is out that much in one dimension I have heard nothing but good things about this plane.

Please stay tuned on this topic Bob i'd like to compare your ultimate to mine when you get better access to it.

Thanks

Brad

OneFeather

I also have a NIB DP Ultimate which will be my second Winter project, so I've not started on it yet. Still I'm getting ready and gathering all the various bits and doing some studying. Still need to get the engine though (next on the list).

I studied your pictures and the struts appear to be installed correctly, there is nothing obviously wrong except for the center cabane alignment offset. At 1/4" it's not what I would call severe but does need to be addressed. I definitely would not attempt to adjust the center cabane mount in any way. As you indicated, it is used to determine CG and it is also a critical support component for the entire wing box.

My thinking is that you may not have the interplane strut fittings installed incorrectly, they might be too high in the front or too low in the back. Remove the struts and see if you can't adjust the strut fittings up or down to get the correct alignment. Also check your struts to make sure there aren't any high spots on them top or bottom. Then reattach the struts but don't tighten them down, keeping some room to play with. Re-seat the top wing and check again. You might have to play with this for awhile to get it right but I'd be willing to bet that you can get everything seated just fine without too much work. Verify your incidence after everything's together.

If this doesn't work as a last resort I would fill the top wing mounting tab holes with a dowel and epoxy and then re-drill - carefully making sure that the wing incidence remains at 0. But like I said this would be a last resort only. If you take this route understand that you will be affecting the CG as well because in a bipe the CG is determined by the MAC of both wings. You'll need to keep this in mind for initial flight testing so that you're not nose heavy. You've got some room to play with though, just don't go all the way forward with the CG on the first flight (assuming you end up with the same alignment issue as in your pictures).

Good luck and post here with how it's going. If you need measurements I can take some on mine which is still in the box.

Bill

bradleyban

Thanks Bill

I will keep an update of what I'm doing and post pics when I get a chance. Everyones advice they gave me so far is that my interplane stuts are backwards, but they will only fit one way. I can bolt this together in this manner and everything seems to be square but there is a little bit of force involved. I havn't gone through checking the wings incidence yet but what I can only see so far is that my bottom wing incidence is off. The center line of the plane is very hard to access without a top hatch. I'm kinda putting that stuff aside right now and I want to get my motor mounted and pull pull cables all hooked up. I'm having a hard time with a motor mount right now. The stock mounts in my kits have a warp in them so I don't want to use them. I went to Great Hobbies today about 2 hours away and picked up a set of dubro shock mounts but they don't fit my motor the carb hits the rubber mount even if i rotate the intake a bit. I'll get it all figured out I got lots of winter left. I think i'm gonna make me a set of mounts. I work in a cnc shop so I should be able to make a set no problem.

Ohh and if anyone is curious what im set-up with I will be using a saito fa180 4 futaba S9650 on ailerons - hitech HS-6985HB on the rudder and hitech HS-5625MG for the elevator

OneFeather

Hi Brad,

Right - the struts are not backwards, otherwise your alignment problem would much worse! Perhaps the thinking is that they are upside down? But I believe that you've already tried that and also they appear to be symmetrical. If your lower wings incidence is off, that would explain everything, I'm just not sure how that would happen. You don't need a hatch to refer to the center (thrust) line, because the stab sits directly on the thrust line, at +1.5 degrees with both wings at 0.

What a nice bonus that you work at a CNC shop! My initial choice was the Saito 180, but I've decided to go with the Syssa 180. So I've got a pristine Saito 180 sitting around that I'll be selling soon. I love the Saito's, but decided I really wanted to go gas with this one.

Good luck with the engine install and post some pictures of your custom engine mounts.

Bill

bradleyban

Ohh do I ever have some ideas for an engine mount. Custom one off mounts. Jeeze listen to me I sound like pimp my airplane. lol I'll try and shoot some footage of making them too.


My bottom wing could have a slight twist in the bottom wing. I don't think it would take much of a twist to mess up the alignment. I'm currenlty trying to get all the pull pull cables hooked up.

bradleyban

Build Update:

I made some new motor mounts with clearance for the carb and they look dang sweet too.

The first picture is one in the machine running. It looks like the spindle is stopped but it's actually running 9000 rpm. The second picture is the part finished in the machine minus the left over stock on the back and the last photos attached to the motor.

The Pull pull set up is done for the rudder and I'm waiting on hardware for the elevator.

bradleyban

I don't know why the pictures are so big and some arn't but they are nice and clear anyways



Fixed it

bradleyban

Just finished test fitting the engine!!

OneFeather

To say that I'm impressed would be an understatement. That's some fine work there my friend! And I see you put that Dubro shock mount kit to good use too. I really like the way you provided some clearance for the Carb, and the engraving - a custom one off fer sure. Nice work!

Bill