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Author Topic: Next Steps after WS  (Read 2755 times)
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ceandra
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« on: May 23, 2017, 03:24:55 PM »

Friends:

While my team struggled due to plane damage at Nationals, they are stoked and want to get back in the gym. One mentor online has suggested Pennyplane, or F1M, for the kids to maybe try out.

Can anyone tell me any contests in the lower rockies area (we are in NM) in the summer or fall that might be a good experience for my mid-schoolers? They both have AMA membership now. AMA really helped out in getting insurance for a gym we rented at Dayton.

Thanks
Chuck
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bjt4888
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« Reply #1 on: May 24, 2017, 11:03:39 AM »

Chuck,

Great job getting students to Nationals! Too bad about airplane damage at the competition.

What I particularly like about F1M for a next step after SO is that several of the AMA. National records for Junior have not been set yet. So, a simple "Penny Plane like" F1M could set a first-time record. I have tried to get students to do this for several years.

I think that the NFFS website has a complete contest calendar on it.  Sorry I can't get the link right now as I'm between meetings at work.

Brian
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JasperKota
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« Reply #2 on: May 28, 2017, 12:03:33 PM »

I believe this is the link Brian was talking about: https://freeflight.org/competition/master-calendar/
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ceandra
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« Reply #3 on: May 29, 2017, 07:17:26 PM »

Got it, thanks.

Kids seem interested in trying F1M or LPP, we'll see how their summer schedule shapes up.

Chuck
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calgoddard
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« Reply #4 on: May 29, 2017, 10:09:33 PM »

Chuck -

You might consider recommending the new AMA P-18 event to your students.  The rules are similar to the 2017 WS rules.

LPP and F1L are quite a step up from WS airplanes.  Wood selection is very important in constructing LPP and F1L models near minimum weight. The minimum legal weight for an LPP is 3.1 g.  The minimum legal weight for an F1L is 1.2 grams.  LPP and F1L models are somewhat similar in size to a WS airplane, yet they weigh only a fraction of the weight of a WS model.  You must build your own props for LPP and F1L models, which is itself a challenge.



 
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ceandra
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« Reply #5 on: May 29, 2017, 10:24:29 PM »

Thanks CalGoddard.

Was looking at F1M, not F1L, which is still half the weight of WS planes. However, it would appear that this class is not limited to balsa, so some of Ol Bill's construction techniques for LPP are of interest (carbon rod pairs for spars).

The kids did build their own props this year, using Bill's carbon hub design and bucket blades cut from a Solo cup.  We did form some balsa blades on a spray paint can, but did not use them in the event. We also formed our rib material on a jug, so they do have experience forming.

We could modify a WS plane to meet P18 rules, plus build a F1M. WS primarily needs shorter MS for P18, and different prop.

Chuck
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calgoddard
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« Reply #6 on: May 29, 2017, 10:39:45 PM »

Chuck -

My mistake.  I should have addressed F1M instead of F1L.

I see after looking it up that F1M has a minimum weight of 3 grams, close to the LPP minimum weight.

With the background and experience possessed by your students, both LPP and F1M would be reasonable for them to try.

IMO, there was no need to build custom balsa props for the 2017 WS event.  The weight budget was so liberal, and the plastic props are very durable, and have helical shaped blades.  I got good results with my 2017 WS models by cutting down, and re-pitching, the "fat" Ikara prop.  The RPM of the "skinny" cut-down Ikara prop was too high to get max times under the 2017 WS rules.   

Good for you for mentoring these students.
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Olbill
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« Reply #7 on: May 29, 2017, 10:52:53 PM »

I think they could do an LPP just fine. I would be willing to donate some suitable MS wood. The only other place where you need to be careful of weight is in the prop blades. Find a good sheet of 1/32 and sand it down to .025 and you're in business.

Don't worry if the model is a little overweight - just don't let it get to be a lot overweight.

Note that I'm using rectangular carbon spars now instead of the stacked rods. They are lighter, strong enough and they cut out a construction step.

You can fly an LPP as an F1M if you use a 1.5 gram motor.

IMO P-18 might be a useful class for a raw beginner. Your kids are way past that point. Let them build a for real indoor model.
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ceandra
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« Reply #8 on: May 29, 2017, 11:05:50 PM »

Yes, we did not end up using the balsa blades, just played with forming them. When we found the Solo cups in the pantry, and checked them through the excel sheet for bucket props, they were a good match and made a nice flaring prop, and as you note, the weight was not an issue. Unfortunately they damaged the tail in inspection and did not catch it until post-flight inspections. We had over two minutes working Thursday night in a rented gym, but did not do well in the competition. Learning experience, we'll work on better observation skills next year!

Chuck
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ceandra
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« Reply #9 on: May 29, 2017, 11:11:12 PM »

Thanks Bill! I'll get in touch when we get closer to building. We got together this morning to exchange boxes form Nationals, and agreed we all need a month off!

What weight of 1/32 wood is needed? Should it be contest (4-6lb)? I have a ton of lightweight 1/16, not sure i have 1/32, will have to explore my stash.

Now on to racing. My traditional hobby is R/C pylon racing (Q40), but this Spring I missed two big races for SO. I guess I am hooked now!

I was looking at the rectangular spars as well. Good to hear its working for you. Are you getting them from CST? Are you tapering?

Thanks
Chuck
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Olbill
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« Reply #10 on: May 30, 2017, 07:08:43 AM »

If you're going to make a big prop like mine then you should look for 4# 1/32.

Ribs can be 4# 1/16 but something more like .050" would be better. Sanding will work for that.

I taper sand the flat side of the spars but it's maybe just 8 or 10 strokes each end. That saves me several milligrams.

Or you could build an all balsa LPP and use hobby shop wood per whatever plan you select. Of course you know I highly favor my own model!
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ceandra
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« Reply #11 on: May 30, 2017, 11:00:22 AM »

Bill:

Thanks for the feedback! At some point I would love to design my own, but I have so much to learn before that! Seeing your success in these classes, it only makes sense to start with your designs. Thanks for sharing them on the exchange.

For the ribs, at least for SO, we have used 4-6# 1/16 wood, formed on a jug while wet, and then sliced with a balsa stripper, giving us a rib thickness of about 3/64", with grain following the rib shape. Really helped with strength, especially in helicopters where the ribs had a lot of curvature.

What is your source for the carbon rectangle? I presume its the pull-truded type, rather than carbon laminate stripped to width?

Definitely getting stoked to try this, I think I'll spend my "time off" this month acquiring materials.

Thanks
Chuck
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Olbill
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« Reply #12 on: May 30, 2017, 11:57:35 AM »

From CST
http://www.cstsales.com/sale.html
Clik "Product List"
Under "Carbon Composites......" select "rods" or "strips"

0.016" x 0.039" x 39.37" long
0.4 mm x 1.0 mm x 1 m, 0.5 grams         T714Lm    $3.05
(one piece makes two wing spars)

0.010" Dia., 39.37" long
0.28 mm x 1 m, 0.1 grams         T301Lm    $3.75
(two pieces makes tip plates for one model)

0.020" Dia., 39.37" long
0.5mm x 1m         T305Lm    $2.80
(one piece makes 3 stab spars)

For material for one model the total with shipping to my zip code is about $24. For 2 models about $37.

   
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mkirda
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« Reply #13 on: May 30, 2017, 12:11:22 PM »

Personally, I find the 0.020" rod really marginal for stab spars.
I often observe them too often tucking at speed. 

They could potentially be improved with about 3" of boron top/bottom. Maybe 3.5-4".
Or just a layer of 1K tow.

When I first started building LPP with my kids, we just cut out 5.5# c-grain 1/32" blades. No sanding required.
They did well enough. As a first prop, that is what I would recommend.
I do have fiberglass prop forms for LPP available now, with camber built in.

Regards.
Mike Kirda
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ceandra
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« Reply #14 on: May 30, 2017, 01:22:18 PM »

Thanks guys, great information.

Chuck
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calgoddard
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« Reply #15 on: May 30, 2017, 01:38:38 PM »

Bill -

Can you please explain these statements in Reply #7:


Note that I'm using rectangular carbon spars now instead of the stacked rods. They are lighter, strong enough and they cut out a construction step.


I assume you are referring to wing spars.
 
Can you give me a link that describes your current design where the prop spars are made of multiple carbon fiber rods that twist so that the blades flare at high torque?

Thank you.
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ceandra
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« Reply #16 on: May 30, 2017, 01:45:26 PM »

I believe he is referring to the wing spars. If you look at some of his plans, he was using two 0.010 carbon rods stacked to make it stiffer in the vertical direction. Apparently the rectangular pull-truded rods are as stiff or stiffer, and without the glue bonding two rods together, can be lighter.

Chuck
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mkirda
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« Reply #17 on: May 30, 2017, 01:49:54 PM »

Not 0.010" rods. Two 0.020" rods glued together on the original planes for wing spars.

Newer version with rectangle is reportedly lighter and at least as strong.
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Olbill
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« Reply #18 on: May 30, 2017, 01:50:32 PM »

Personally, I find the 0.020" rod really marginal for stab spars.
I often observe them too often tucking at speed. 

They could potentially be improved with about 3" of boron top/bottom. Maybe 3.5-4".
Or just a layer of 1K tow.

When I first started building LPP with my kids, we just cut out 5.5# c-grain 1/32" blades. No sanding required.
They did well enough. As a first prop, that is what I would recommend.
I do have fiberglass prop forms for LPP available now, with camber built in.

Regards.
Mike Kirda


I've never had a problem with stab spars.

I'm sticking by my recommendation for prop blades. My wing and stab are heavier than all balsa models. If you want to be close to the right weight you need to be careful somewhere.
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Olbill
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« Reply #19 on: May 30, 2017, 01:52:47 PM »

Not 0.010" rods. Two 0.020" rods glued together on the original planes for wing spars.

Newer version with rectangle is reportedly lighter and at least as strong.

My recollection is that the rectangle isn't quite as stiff as the double .020 rods but it is more than adequate. Watch for near vertical launches next month.
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ceandra
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« Reply #20 on: May 30, 2017, 01:56:48 PM »

Oops, my typo on the spar rods, 0.020.

And Thanks Bill for clarification.

Chuck
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mkirda
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« Reply #21 on: May 30, 2017, 02:07:12 PM »

I've never had a problem with stab spars.

I'm sticking by my recommendation for prop blades. My wing and stab are heavier than all balsa models. If you want to be close to the right weight you need to be careful somewhere.

I agree, Bill. Your model is backed off to such a degree when I have seen it flying that the stab spars do not tuck.

However just about everyone else I have seen with same 0.020" rods have severe problems with high torque launches or during collisions.
Bud/Jim/Andrew at Rantoul all have this issue.

Another potential solution: Stack a 0.010" rod on the bottom. Sand a taper in it from center to the ends.

Regards.
Mike Kirda



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Olbill
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« Reply #22 on: May 30, 2017, 02:19:08 PM »

I've launched at max torque at Lakehurst, Tustin, St. Lukes and Rantoul. Never had a stab problem.
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ceandra
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« Reply #23 on: June 16, 2017, 07:47:09 PM »

Bad news. I got my CST order, and no 0.010 carbon. Not only was it out of stock, they do not expect to get any more, perhaps ever. The supplier was sold to a Chinese company, and the minimum orders are too large.

Anyone know of an alternate source for 0.010 carbon rod?

Thanks
Chuck
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Olbill
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« Reply #24 on: June 16, 2017, 09:37:08 PM »

Bummer!

You can split .020 rod with a single edge razor blade. When I did it that way I would split several pieces and then try to find ones that match.

This is going to affect some F1D fliers as well.
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