Author Topic: Building another one (Read 26869 times)

Doug Moon · « **on:** December 26, 2012, 10:54:31 PM »

A while back I started a new Riff Raff.

I have been snapping some photos along the way.

1. The list! I build from scratch. Not even a plan. The list helps me stay on track. (Note step 27)
2. The ribs. I cut and sanded ribs to match the lost foam jig from 1/16 balsa I had on hand.
3. Sig wood order. Enough for several planes.

Doug Moon · « **Reply #1 on:** December 26, 2012, 10:59:05 PM »

4. Jig setup with shims and the trailing edge stock.
5. About half the ribs installed. You can see the leading edge molds drying in the back ground.
6. All the rib installed.

Doug Moon · « **Reply #2 on:** December 26, 2012, 11:17:48 PM »

7. Trailing edge sheer webbing. It is a must with Warren Truss rib layouts. It keeps the TE from sagging.
8. I sheer web the back end prior to installing the TE itself. This helps level it out.
9. The wing completed with cap strips but no center section sheeting 6.0 oz. at that stage, pretty average. Ready for bell crank, tip weight box, tips, and line slider.
10. Installed bell crank post. Lead outs, and short push rod. Bell crank is completed and ready to go in. Once the bell crank was installed onto the post I then spun it with compressed air at a very high speed for a good while in both directions. This "wears" it in. A little trick we do to the wheels in the pine wood derby. After just a few minutes of the high speed spin this thing is smooth as silk.

This is the 16th wing built out of this jig. The foam rib forms have seen their better days. Plus I have been working all these years off of Bob Hunt's earlier version, around 2001-2002, of the steps needed to complete the wing. Plus a few turns of my own I have picked up along the way. Once this one was removed from the jig for the first time it had an odd warp in it. I am not sure it was actually a warp. Upright or inverted the trailing edge would lay nice and flat in the jig. But inverted the leading edge was very slightly raised. This is an odd one. I think the rib shapes are finally showing they are not all that perfect anymore. A conversation with Bob and I would try very tight cap strips to see if they might push the wing into place. This along with some good old water, some weights, and shims it was straightened right out and is holding this shape nicely over the past week.

I have since read Bob's updated methods to the lost foam building system and will be making some sorely needed changes to my routine the next time I do this. Of course a new jig will be in order as well. Or I might just go foam.

I will keep you posted as I move along.

Thanks for looking.

MarcusCordeiro · « **Reply #3 on:** December 27, 2012, 04:38:36 AM »

Thanks for posting the pics Doug.
Any source of info is very welcomed, since I'm at Lost Foam 101...
Bob sent me this pic showing the support ribs to prevent the sagging.
Gotta ask him if the TE shearwebs are still necessary though.

Marcus

Doug Moon · « **Reply #4 on:** December 27, 2012, 07:45:33 AM »

Yep, that's Bob's blue building table. I would think with the support ribs in place you would be good to go without the sheer webbing. But either way choose you will have to so something to keep it from sagging.

Bob Hunt · « **Reply #5 on:** December 27, 2012, 08:43:31 AM »

"I have since read Bob's updated methods to the lost foam building system and will be making some sorely needed changes to my routine the next time I do this. Of course a new jig will be in order as well."

Hi Doug:

Glad the new instruction booklet was helpful. I want to repeat the offer here that I made elsewhere on this forum to send those PDF files of the updated Lost-Foam instructions to anyone who wants them. There is no charge for this, and they will be sent in four separate email messages as the four PDF files are quite large. Simply email me at robinhunt@rcn.com and request the Lost-Foam instruction PDF files.

Your wing looks great! I'm currently (us electric guys use that word a lot...) working on a Lost-Foam Vulcan wing for use in the project model for a Power 15 system that I'm writing about in my MA column. Here are a few photos of that one.

Later - Bob Hunt

Eric Viglione · « **Reply #6 on:** December 27, 2012, 09:25:31 AM »

Aha! Your secret is out Doug! Step 15! No wonder!
If I only I had elves working in my shop...

Looks great Doug!
EricV

Doug Moon · « **Reply #7 on:** December 27, 2012, 10:02:39 AM »

Quote from: Eric Viglione on December 27, 2012, 09:25:31 AM

Aha! Your secret is out Doug! Step 15! No wonder!
If I only I had elves working in my shop...

Looks great Doug!
EricV

Dang it! I meant to leave that part out.

Tom Niebuhr · « **Reply #8 on:** December 27, 2012, 10:10:20 AM »

Doug,
Does Santa know that you kidnapped one of crew?

Avaiojet · « **Reply #9 on:** December 27, 2012, 05:34:58 PM »

Doug & Bob,

Happy Holiday!

Thanks for the tex and the great photos!

You guys do excellent work, Kudos to you both!

I'm paying close attention and reading up, BTW.

Doug,

Your TE sheeting? Looks like 3/32". Correct or are you using 1/16"?

Charles

Doug Moon · « **Reply #10 on:** December 27, 2012, 10:36:24 PM »

All of the sheeting is 3/32"

RandySmith · « **Reply #11 on:** December 28, 2012, 01:14:06 PM »

Quote from: Doug Moon on December 26, 2012, 10:54:31 PM

A while back I started a new Riff Raff.

I have been snapping some photos along the way.

1. The list! I build from scratch. Not even a plan. The list helps me stay on track. (Note step 27)
2. The ribs. I cut and sanded ribs to match the lost foam jig from 1/16 balsa I had on hand.
3. Sig wood order. Enough for several planes.

Lookin GOOD !

Randy

Doug Moon · « **Reply #12 on:** December 28, 2012, 11:22:32 PM »

Tonight I installed the BC and the center section sheeting. I put the BC in as high as I could and still have good clearance over the wing gear mounts. The LO is very close as it travels over that rib. I am going to take the sheer webbing out at that location and work it over some with the Dremel to get a little more clearance. Shouldn't be a problem. At 8 oz now, most of that post will come off later when the wing goes into the fuse. That should cut some weight out.

Next up will be tips, slider, and TW box.

RandySmith · « **Reply #13 on:** December 29, 2012, 09:16:43 AM »

Quote from: Doug Moon on December 28, 2012, 11:22:32 PM

Tonight I installed the BC and the center section sheeting. I put the BC in as high as I could and still have good clearance over the wing gear mounts. The LO is very close as it travels over that rib. I am going to take the sheer webbing out at that location and work it over some with the Dremel to get a little more clearance. Shouldn't be a problem. At 8 oz now, most of that post will come off later when the wing goes into the fuse. That should cut some weight out.

Next up will be tips, slider, and TW box.

Doug
is the high point of the airfoil on that wing in a straight line? or is is swept back? picture looks as if it is a straight taper

Randy

Bill Little · « **Reply #14 on:** December 29, 2012, 02:09:05 PM »

Your work looks great, Doug! Is everything else going to be like the Riff Raff you are now flying?

Good Luck!
Bill

MarcusCordeiro · « **Reply #15 on:** December 29, 2012, 02:25:45 PM »

Talked to Bob about those half ribs and the shearwebbing and he said "Do both..."

Marcus

Doug Moon · « **Reply #16 on:** December 29, 2012, 08:48:18 PM »

Quote from: RandySmith on December 29, 2012, 09:16:43 AM

Doug
is the high point of the airfoil on that wing in a straight line? or is is swept back? picture looks as if it is a straight taper

Randy

Randy,

The spar is straight and gives that illusion. But the highpoint sweeps back with the wing.

Doug Moon · « **Reply #17 on:** December 29, 2012, 09:06:13 PM »

Put in the tip weight box today.

The open box looks a little dirty because it is a used one. Cleaned it up, checked glue joints, added any that was needed and installed it.

Chuck_Smith · « **Reply #18 on:** December 30, 2012, 05:21:42 AM »

Doug,

On the PSP bellcrank do you put the brass over the leadouts and then bend it or do you have a method that keeps the tubing from crimping on the inside of the bends and then feed the cable through it? Those cranks are so thick I can never get a result I'm pleased with.

I aways feel like I add some sharp corners bending the tubing and that replaces one problem with another. Maybe I'll just start using the bushed ones from RSM. I just ordered a $40 spinner, I might as well get a $20 bellcrank to go with it!

Chuck

john e. holliday · « **Reply #19 on:** December 31, 2012, 09:51:12 AM »

Looking at the pictue of the bellcrank, it looks likeDoug does like I do. Chamfer the holes in the bellcrank or bevel them. Using brass or copper I myself run the tubing thru a torch to red hot and let cool. Makes bending the tubint easier. Aso the tubing is just large enough for the cable to go thru. Now I let Doug explain his method.

Avaiojet · « **Reply #20 on:** December 31, 2012, 10:17:42 AM »

Doug,

Nice work!

Like that balsa WB cover. I beat myself up sanding ply.

Next time!

Charles

Derek Barry · « **Reply #21 on:** December 31, 2012, 11:37:14 AM »

Rock on Doug, but the Cutlass is coming for you...

Derek

MarcusCordeiro · « **Reply #22 on:** December 31, 2012, 12:56:18 PM »

Quote from: Derek Barry on December 31, 2012, 11:37:14 AM

Rock on Doug, but the Cutlass is coming for you...

Derek

Things are getting more interesting by the minute...

Marcus

Avaiojet · « **Reply #23 on:** December 31, 2012, 01:01:27 PM »

Quote from: MarcusCordeiro on December 31, 2012, 12:56:18 PM

Things are getting more interesting by the minute... VD~Marcus

Marcus,

You're right!

Doug has a great build going here. I wish I knew what the Riff Raff looked like?

Doug,

I just noticed something! You have twice as many "photo hits" as I do over at The LOSER. The "weight box photos," that is?

No idea why, but KUDOS!!

Keep up the good work, obviously, you pay a great deal of attention to detail.

Charles

Derek Barry · « **Reply #24 on:** December 31, 2012, 01:38:22 PM »

Quote from: Avaiojet on December 31, 2012, 01:01:27 PM

Marcus,

You're right!

Doug has a great build going here. I wish I knew what the Riff Raff looked like?

Doug,

I just noticed something! You have twice as many "photo hits" as I do over at The LOSER. The "weight box photos," that is?

No idea why, but KUDOS!!

Keep up the good work, obviously, you pay a great deal of attention to detail.

Charles

Maybe because he is a National Champion and an excellent builder. Just guessing here.

Derek

Steve Fitton · « **Reply #25 on:** December 31, 2012, 02:23:24 PM »

I'm still not sure why you need a new plane. Last years model worked pretty good!

But the new one looks awesome so far! Your instruction list is so important. Sequence is everything in building.!

Avaiojet · « **Reply #26 on:** December 31, 2012, 02:40:48 PM »

Quote from: Derek Barry on December 31, 2012, 01:38:22 PM

Maybe because he is a National Champion and an excellent builder. Just guessing here.Derek

Derek,

I didn't know that.

Thanks for the heads up.

Charles

Doug Moon · « **Reply #27 on:** December 31, 2012, 04:10:26 PM »

Quote from: Chuck_Smith on December 30, 2012, 05:21:42 AM

Doug,

On the PSP bellcrank do you put the brass over the leadouts and then bend it or do you have a method that keeps the tubing from crimping on the inside of the bends and then feed the cable through it? Those cranks are so thick I can never get a result I'm pleased with.

I aways feel like I add some sharp corners bending the tubing and that replaces one problem with another. Maybe I'll just start using the bushed ones from RSM. I just ordered a $40 spinner, I might as well get a $20 bellcrank to go with it!

Chuck

The BC is an old Windy delrin crank. I heat up 1/16" brass tubing cherry red then let it cool on its own. That makes it nice and soft. I put the LO through the tube then through the crank. Bend by hand. Then work them back and fourth until smooth.

Yeah it is a think one for sure. But the thickness helps fight against and wobble as it wears. But I have pulled them out of planes with 100s and 100s of flight with no play or wear.

Doug Moon · « **Reply #28 on:** December 31, 2012, 04:13:43 PM »

Quote from: Ty Marcucci on December 31, 2012, 12:20:25 PM

Hi Doug. One question. Your TE shear webs are cut with the grain going with the span. Does it make any difference if they are cut with a vertical grain? I've seen both, done both, but is one better than the other? Yours are much easier to cut and trim to size. Thanks in advance.

The TE sheer webs are there to keep the TE sheeting from sagging. Long grain will work fine for this application. I find the height of what it should be where the TE touches the rib. Then I use a stripper, the balsa kind, and cut some 1/16". I place them in and it levels the TE and supports it.

I also do this at the back end of the TE sheeting prior to installing the actual trailing edge. That way there is no dips at the back that have to be filled.

Doug Moon · « **Reply #29 on:** December 31, 2012, 04:18:40 PM »

Quote from: Steve Fitton on December 31, 2012, 02:23:24 PM

I'm still not sure why you need a new plane. Last years model worked pretty good!

But the new one looks awesome so far! Your instruction list is so important. Sequence is everything in building.!

The winner has a couple of issues. It's tail heavy. I had to add 1.25 oz of lead under the motor. I plan to move the numbers around a little on the fuse.

And.... the stupid canopy got deformed at the last contest. That repair is going really make me insane!

The current nose is 9" tail is 17 7/8". I am thinking 9 3/4" nose and 18" tail. Maybe it wont hunt so bad inverted.

MarcusCordeiro · « **Reply #30 on:** January 01, 2013, 12:36:37 PM »

Doug
I hope you don't mind my asking, but I got kinda curious...
Is there any specific reason for the 3/32 sheeting?
Thanks.

Marcus

Doug Moon · « **Reply #31 on:** January 01, 2013, 07:34:17 PM »

I use 3/32 sheeting as the 1/16 would sag between ribs or give up over time.

I used 1/16 sheeting on one of my first 60 sized stunters and it lasted about 350-450 flights before the sheeting buckled. Plus the 3/32 is a little more forgiving and you can be a little more aggressive with it.

Doug Moon · « **Reply #32 on:** January 01, 2013, 07:35:05 PM »

Installed the outboard tip today. Looks like total crap. Gonna have to cut it off and start over. AARRGGGHHHH!!

And I had to stop down and install a brushless system in my RC car. Waiting on LIPOs to come in.

Doug Moon · « **Reply #33 on:** January 01, 2013, 10:32:52 PM »

I went back out and built another tip.

I use the Tom Morris method.

(The numbers are the picture numbers, the steps are in the right order)

1. I cut out a plan form frame of the tip shape I want to use. I also cut a rib that matches the last rib on the wing. Then I sand it off about 1/16-3/32 all the way around.
2. I glue the tip shape onto the rib.
3. Next I prepare two pieces of 1/16 sheeting. One for top and one for bottom. The grain will run with the span.
4. Then I wrap the rib and frame with the sheeting. The grain running with the span makes this easy. But, it is VERY important to place those two small triangle pieces from the rib to the frame prior to wrapping the sheeting. They keep things square as you work the sheeting down. Otherwise it WILL pull the rib out of alignment and the tip will not be straight. You cant really see it but the two triangle pieces don't actually touch the sheeting. There is a gap on purpose. In the past I have had them touch for support. But after dope and covering and sanding they create a highpoint and sometimes can even create a crack. I leave them a tad short on purpose to keep from creating that hard spot.
7. Sand off excess. Make the initial rounding of the edges. Check it to make sure it is straight.
5. Weight is good.
6. Install and rough it in. You can see I had to fill it some at the TE. I did as well at the LE. I always use wood to fill the gaps. Even if it is paper sliver I fit in there and hit with the thin CA.

Sorry the pics got out of order. I had to go back and rotate one.

I think this one is a keeper.

Next will be the inboard tip. It is the same except I put the line slider in it. I will show a few pics of that along the way as well.

MarcusCordeiro · « **Reply #34 on:** January 01, 2013, 11:13:55 PM »

Quote from: Doug Moon on January 01, 2013, 07:34:17 PM

I use 3/32 sheeting as the 1/16 would sag between ribs or give up over time.

I used 1/16 sheeting on one of my first 60 sized stunters and it lasted about 350-450 flights before the sheeting buckled. Plus the 3/32 is a little more forgiving and you can be a little more aggressive with it.

Thanks!

Marcus

George Grossardt · « **Reply #35 on:** January 02, 2013, 05:14:05 PM »

Doug,

Can you tell us what gauge leadout wire you are using? Guessing it is .027.

I am using the same bell crank in my Cardinal build right now and am deciding what wire to use.

George

Howard Rush · « **Reply #36 on:** January 02, 2013, 07:20:16 PM »

This airplane has me concerned. Will you be flying in Open or Expert at the Nats this year, Doug?

Doug Moon · « **Reply #37 on:** January 02, 2013, 07:36:10 PM »

Quote from: Howard Rush on January 02, 2013, 07:20:16 PM

This airplane has me concerned. Will you be flying in Open or Expert at the Nats this year, Doug?

I will be working in Open this year.

What concerns do you have?

Doug Moon · « **Reply #38 on:** January 02, 2013, 07:37:42 PM »

Quote from: George Grossardt on January 02, 2013, 05:14:05 PM

Doug,

Can you tell us what gauge leadout wire you are using? Guessing it is .027.

I am using the same bell crank in my Cardinal build right now and am deciding what wire to use.

George

George,

I got the LO wire from Tom Morris a couple of years ago. It is fairly thick and smooth. Honestly, I cant remember the size. Sorry. If I get it I update the post for you.

Doug

George Grossardt · « **Reply #39 on:** January 02, 2013, 08:51:26 PM »

No problem Doug. I am enjoying this thread.

Howard Rush · « **Reply #40 on:** January 02, 2013, 11:26:16 PM »

Quote from: Doug Moon on January 02, 2013, 07:36:10 PM

What concerns do you have?

I am concerned that you flying that airplane could get a humiliating number of points more than I get.

Derek Barry · « **Reply #41 on:** January 03, 2013, 03:59:33 AM »

Quote from: Howard Rush on January 02, 2013, 11:26:16 PM

I am concerned that you flying that airplane could get a humiliating number of points more than I get.

Says Mr. Front Row Impact...

Derek

RandySmith · « **Reply #42 on:** January 03, 2013, 11:51:26 AM »

Quote from: Howard Rush on January 02, 2013, 11:26:16 PM

I am concerned that you flying that airplane could get a humiliating number of points more than I get.

How many does it take to be humiliating

??

I don't really think you need worry about being down on points, your dogs always look pretty good

Randy

Howard Rush · « **Reply #43 on:** January 03, 2013, 01:00:11 PM »

Looking good on the ground doesn't pay that well in points compared to other things one's airplane is supposed to do. The latter is my concern.

Derek Barry · « **Reply #44 on:** January 04, 2013, 04:18:41 AM »

Quote from: Howard Rush on January 03, 2013, 01:00:11 PM

Looking good on the ground doesn't pay that well in points compared to other things one's airplane is supposed to do. The latter is my concern.

Agreed.

Derek

Doug Moon · « **Reply #45 on:** January 11, 2013, 10:04:02 PM »

I got back in the shop yesterday and today.
I built the inboard tip and slider.

I use a piece of basswood inserted in the frame as the slider. The slider is incorporated as part of the tip.

1. Tip shape
2. Layout a piece of basswood that will be the slider
3. Drill the holes for the LOs at the proper angle, this way when the LOs exit the wing there is no bind.
4. Tap the holes 4/40
5. Connect the holes with band saw, careful not go through both ends. Then fill the cut end with a sliver of balsa.

Doug Moon · « **Reply #46 on:** January 11, 2013, 10:20:35 PM »

Inboard tip continued.

6. Test fit the nylon 4/40 screw. I hand drill a small hole lengthwise through the nylon screws. The LOs will pass through the screws. To adjust, you unscrew and slide forward or back and screw into the new hole.
7. Build the frame just as the outboard tip I use two support pieces on each side. Sheet with 1/16 balsa grain running with the span, careful to make sure the 1/16 sheeting is touching both the rib and the frame at the same time when I glue it on. That way it wont pull the rib out of shape when I fit it all the way around.
8. Trim away excess and initial sanding of the edge. 10g, the weight is good.
9. Glue it onto the wing sand it out
10. Different angle after sanding
11. Completed wing, 63" span 9.5 oz.

John Sunderland · « **Reply #47 on:** January 12, 2013, 04:11:40 AM »

Quote from: Doug Moon on December 31, 2012, 04:13:43 PM

The TE sheer webs are there to keep the TE sheeting from sagging. Long grain will work fine for this application. I find the height of what it should be where the TE touches the rib. Then I use a stripper, the balsa kind, and cut some 1/16". I place them in and it levels the TE and supports it.

I also do this at the back end of the TE sheeting prior to installing the actual trailing edge. That way there is no dips at the back that have to be filled.

I built a lost foam Geo Bolt wing in 93 and somehow forgot the sheer web at the TE! I found out the hard way how much strength this adds to the TE when I folded the wing two weeks before the Nats.

Sagging is just a cosmetic reason for sure. DO NOT omit this step with a lost foam with a 1/4 TE high aspect wing!!

John Sunderland · « **Reply #48 on:** January 12, 2013, 04:16:16 AM »

Deleted message...just a fumble fingered quote of my last post.

Glenn (Gravitywell) Reach · « **Reply #49 on:** January 12, 2013, 04:05:28 PM »

Thank you so much for the wing tip slider idea. I have been wracking whats left of this old brain trying to figure out how to do a slider on a Spitfire wingtip....and there it is!