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Apr 25, 2017, 08:56 PM
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gobigdave's Avatar
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Discussion

I'm stuck


Not really a question. I'm just stuck on my Curare build because I hit a spot where I'm not sure how to continue, and I don't want to screw it up. It's been a while since my last pattern plane build (30+ years!), and this is one thing I haven't done.

I'm adding wheel wells to my built up wing. Done plenty on foam wings, but none on built up wings. Normally, it would be simple, but throw in a rib and a wing tube to work around, and it gets a little nutty. I feel I need some form of real wheel well to support the sheeting. Otherwise, it will be WAY too easy to crack the sheeting.

Please help talk me down so I can get over it and just try something.
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Apr 25, 2017, 09:01 PM
AndyKunz's Avatar
Dave,

You should check out the Classic Pattern forum. A lot of guys there can help you too.

http://www.rcgroups.com/classic-pattern-flying-722/

Andy
Apr 25, 2017, 09:07 PM
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gobigdave's Avatar
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Oh, I live in the classic pattern forum. I figure I would start here with the balsa builders.
Apr 25, 2017, 09:30 PM
AndyKunz's Avatar
I thought I recognized the name.

Is your wing framed up yet? Got photos? Are you planning on trike or taildragger?

Andy
Apr 25, 2017, 11:57 PM
AMA 46133
SeismicCWave's Avatar
Quote:
Originally Posted by gobigdave
Not really a question. I'm just stuck on my Curare build because I hit a spot where I'm not sure how to continue, and I don't want to screw it up. It's been a while since my last pattern plane build (30+ years!), and this is one thing I haven't done.

I'm adding wheel wells to my built up wing. Done plenty on foam wings, but none on built up wings. Normally, it would be simple, but throw in a rib and a wing tube to work around, and it gets a little nutty. I feel I need some form of real wheel well to support the sheeting. Otherwise, it will be WAY too easy to crack the sheeting.

Please help talk me down so I can get over it and just try something.
I have always used wheel wells on both foam wings or built up wings. It just takes a little time and imaginations. First you need to figure out the size of the wheel and where it should go. Then you can use something existing like a styrofoam coffee cup. If all else fails you make one out of balsa. I just wet and wrap a couple of layers of 1/16th balsa around a PVC conduit. Put some rubber bands over the balsa and let it dry. Then I glue the wheel well in the wing before sheeting. Anchor the wheel well to some thing like a couple of ribs or a spar or even the wing tube. If there is nothing you can add a couple of balsa cross pieces to anchor the wheel well. After the glue dries just sand it to shape and sheet over it.

The attach pictures are a sort of Spitfire looking plane I am building. The plans didn't call for wheel wells but I added them. It is a tail dragger but the same theory holds for a trike main gear.

I like to sheet the bottom first so I can cut out the wheel well from the inside. Then I sheet the top.
Apr 26, 2017, 06:18 AM
Ldm
Ldm
Ldm
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I always use a balsa made well . I read about a method years ago that is super simple and reusable.
You take a role of cheap dollor store duck tape. You unwrap the tape onto a plastic cup to save it , you will put the tape back on the roll when your done.
The process of unwrapping the duck tape you keep trying to see if the duck tape roll fits in the spot you have designed for your wheel well . Remember you have to allow for retracts to clear the wells in a smooth manner.
Once you have the tape roll to the proper size you get your balsa.
You soak the balsa and wrap around the duck tape roll , you can cut the balsa sheet it to fit perfectly around the tape with some trial and error , dont get crazy about trimming the height , that will come after its assembled into the wing and match the sheeting.
I usually hold the balsa to the duck tape with duck tape lol or rubber bands .
If you simply wet the wood some more let it dry you will have a perfect round circle as seen in the pic above.
For me this was the easiest method of getting the well exact .The reason I like wood vs foam ect is that you can add strength by tieing the balsa wing into the balsa well .
Apr 26, 2017, 08:17 AM
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gobigdave's Avatar
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Thanks all! The trick for these wells is that it is not between ribs, and I goofed by handling this after sheeting both sides (like I always did with foam wings).

The well is almost centered over the 3rd rib, and the wing tube encroaches on it as well (trike gear). What I did so far is to build a balsa cup with 2 5/8" inside diameter for my 2 1/4" wheels. Then I cut a slot in the cup to allow for the 3rd rib. Unfortunately, that makes the cup a little fragile to try and shape around that wing tube. I can add more photos tonight, but these are all I have with me.

My original thought was to get the fit close and fill the gaps with the rib and wing tube after. Now, I'm not so sure what kind of fit I'm going to get with that wing tube.

The sheeting is pretty fragile given the large unsupported span. I think a secured balsa well is required to make that sheeting a bit more robust.
Apr 26, 2017, 11:05 AM
AMA 46133
SeismicCWave's Avatar
>>The well is almost centered over the 3rd rib, and the wing tube encroaches on it as well (trike gear). <<

Well the law of "simple" physics dictate that two solids cannot occupy the same space at the same time. So the 3rd rib and the wing tube are not exactly an issue since you have to avoid them no matter whether you plan to use a wheel well or not.

Since the wing tube is fairly critical to the structural integrity of the wing bending load it is best not to touch it. So that will mean you need to offset the wheel well away from the wing tube a little. You can always bend the retract struts a little to offset the wheel to get a bit of clearance behind the wing tube.

OTOH the 3rd rib needs to be out of the way since the wheel itself cannot retract into the wing with the 3rd rib in place whether you use a wheel well or not. The wheel well if done properly is actually going to help you spread the load and reinforce the 3rd rib. You do need to relieve the 3rd rib quite bit to fit the thickness of the wheel well and leave enough clearance for the wheel.
Apr 26, 2017, 11:47 AM
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To be clear, I'm not modifying anything related to the wing tube or the 3rd rib. The kit (from http://www.carolinacustomkits.com) already had a cut out for the wheel, and all the ribs along the wing tube have 1/8" ply doublers.

I have the slot cut in the well cup to clear the rib. It's how best to work around the wing tube that has me stuck. I see three options so far:

1. Shape the edge of the cup to fit around the wing tube. This will leave the wing tube exposed in the well and probably have a hole in the well that could get field debris in it. This was my first idea, but I'm liking it less now.

2. Put a "roof" over the wing tube. Instead of shaping anything, just have one vertical piece of balsa, and one angled to get past the wing tube, and still give enough room for the wheel. This could work, but the cup will be very easily broken while I'm trying to shape things.

3. My really crazy idea would be to use a few trapezoid pieces to make the bottom of the well more of a cone with a flat top. The cone only has to be deep enough to make room for the axel and wheel collar. Since I still need the slot for the 3rd rib, this should provide enough structure. I might even be able to make bottom out of foam.

Option 2 is probably the easiest, but option 3 will be the better looking.

This is why I posted and enjoy these forums so much. All these great ideas and discussion gets the mind working.
Apr 26, 2017, 12:32 PM
AMA 46133
SeismicCWave's Avatar
Quote:
Originally Posted by gobigdave
To be clear, I'm not modifying anything related to the wing tube or the 3rd rib. The kit (from http://www.carolinacustomkits.com) already had a cut out for the wheel, and all the ribs along the wing tube have 1/8" ply doublers.

I have the slot cut in the well cup to clear the rib. It's how best to work around the wing tube that has me stuck. I see three options so far:

1. Shape the edge of the cup to fit around the wing tube. This will leave the wing tube exposed in the well and probably have a hole in the well that could get field debris in it. This was my first idea, but I'm liking it less now.

2. Put a "roof" over the wing tube. Instead of shaping anything, just have one vertical piece of balsa, and one angled to get past the wing tube, and still give enough room for the wheel. This could work, but the cup will be very easily broken while I'm trying to shape things.

3. My really crazy idea would be to use a few trapezoid pieces to make the bottom of the well more of a cone with a flat top. The cone only has to be deep enough to make room for the axel and wheel collar. Since I still need the slot for the 3rd rib, this should provide enough structure. I might even be able to make bottom out of foam.

Option 2 is probably the easiest, but option 3 will be the better looking.

This is why I posted and enjoy these forums so much. All these great ideas and discussion gets the mind working.
You would know best since you are looking at the actual item and we are only looking at pictures. Personally I tend to go for prettiness.
Apr 26, 2017, 12:34 PM
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Yeah, I'm really leaning towards prettiness myself. This is my first pattern build in a long while, and I want it to be right. Then again, I also want to actually fly it this season, and my build time with three very active kids is pretty limited.
Apr 26, 2017, 02:17 PM
AMA 46133
SeismicCWave's Avatar
Quote:
Originally Posted by gobigdave
Yeah, I'm really leaning towards prettiness myself. This is my first pattern build in a long while, and I want it to be right. Then again, I also want to actually fly it this season, and my build time with three very active kids is pretty limited.
It is nice to come back to pattern after a long absent. I have been flying pattern planes on and off since 1968. Back in the early days I only live and breathe pattern. Now I still build and fly pattern majority of the time but I also fly pretty much anything that gets in the air. I don't like to put a schedule constraint on my built. I have built the Kwik Fly 3 from a short kit in about a month but I have also taken many months in building other planes.

Enjoy the built. Enjoy both the journey and the destination. I don't compete anymore so I like the building more than the flying now.
Apr 26, 2017, 08:03 PM
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I started flying young in the mid-70s. I flew through till about 1990, and then life got in the way, and I took a long break.

Here are some of photos I promised. Hopefully, you can see where the slot goes through the well. I can't do anything tonight, but I'm going to try option 2 first and see what it looks like. If I don't like it, then I will go with option 3.
Apr 26, 2017, 08:43 PM
Ldm
Ldm
Ldm
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I know you dont want to do any heavy lifting but if you look at the seafury style retracts, you have the base rail on an angle. The units can retract in an aft manner past the tube and into the area that is semi open. You can then cut the rib and redesign the structure. It super simple, the only part that you have to make sure you get correct is the angle the rails .
Then if you cant built a perfect circle for the well you can build a wheel box and tie all the open ribs together.
I am working on an old P39, some of the same challenges.
The P39 does not have the type of retract that turns aft of the CG like the Seafury but you can see some of the box design to fill in the strength.
May 13, 2017, 07:42 PM
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gobigdave's Avatar
Thread OP
Got the wells done, and I was able to get everything sealed off. I'm happy with how it turned out. Now, I want to seal these up so I can paint them such that I can still use Ultracote on the rest of the wing. This will be my first covered model. I usually glass and paint, but I don't have a suitable area to do that anymore.


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