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Mar 10, 2017, 02:26 PM
Registered User
I scaled the design down to 78 sq. inches and built it with Dollar Store foam (hence it's the DSF-1). I used the power system and servos RA Cores uses for Leadfeather's 22" Yak, although I left the rudder off as this is a test bed (plus I only had two micro servos!).

I came up with the size as the 22" Yak does very well on that power system. As the tail feathers are part of a delta's wing and as the average tail area is about 20% of the wing's area, what I did was estimate the Yak's wing area and multiply it 1.2. I realize that doesn't include the fuse area, but it should be a valid starting point.

Haven't flown it yet, due to the weather. If it works, I'll make a full-house version. If it doesn't...Well, I can always buy another 22" Yak!

BTW, I took a sniffed an open bottle of Craft-Bond and immediately recognized that it smelled exactly like Mod-Podge. So, I used Mod-Podge to glue the KFM part of the wing to the basic wing (letting it dry for a LONG time).

I tried HobbyKing (Bob Smith) EPO glue for some construction and for hinging; it worked fine for construction, but the glue hinges kept cracking and breaking. So I replaced them with Foam-Tac and they seem just fine.

Thank you, Leadfeather, that was a fun project for this long-time balsa builder!

CD
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Mar 10, 2017, 02:36 PM
Registered User
Hey Bill,

I didn't think you built with anything other than balsa

Nice change of pace, eh?

Rob

PS - these planes fly great!
Mar 10, 2017, 05:47 PM
Registered User
Hi, Rob!

About 15-16 years ago, I started making models with foam turtledecks, etc., in addition to foam wings. For belly-landers, foam worked fine..on grass. I glassed the foam with Polycrylic and painted the planes with plastic model paints. Then we lost our grass strip and had to fly off gravel. No way a belly-lander would survive that, so I went back to just wood (one reason I sold the foam corer).

Micki and I moved to a new home in 2015 and joined a new club (NJ Pine Barons). Their field is about a 5 minute drive from us and is GRASS! So, I'm going back to foam! I just read Keith Sparks' book (learned stuff, even after over 45 years of R/C flying!) and am trying to decide on what projects I want to tackle. I really like the ability to do compound curves, without major woodwork! I do plan to do a test & learn project, before I tackle something more complex!

BTW, hopefully, this won't be a 'miss' year for us and JCSF (every other year seems to be the jinx!). Plus, we plan to be at LeHigh this year (with the beagles!).

Bill
Mar 11, 2017, 05:43 AM
Kit Manufacturer
coreman's Avatar
That's what I've found. The Bob Smith isn't flexible enough for hinging

Quote:
Originally Posted by Captain Dunsel
I scaled the design down to 78 sq. inches and built it with Dollar Store foam (hence it's the DSF-1). I used the power system and servos RA Cores uses for Leadfeather's 22" Yak, although I left the rudder off as this is a test bed (plus I only had two micro servos!).

I came up with the size as the 22" Yak does very well on that power system. As the tail feathers are part of a delta's wing and as the average tail area is about 20% of the wing's area, what I did was estimate the Yak's wing area and multiply it 1.2. I realize that doesn't include the fuse area, but it should be a valid starting point.

Haven't flown it yet, due to the weather. If it works, I'll make a full-house version. If it doesn't...Well, I can always buy another 22" Yak!

BTW, I took a sniffed an open bottle of Craft-Bond and immediately recognized that it smelled exactly like Mod-Podge. So, I used Mod-Podge to glue the KFM part of the wing to the basic wing (letting it dry for a LONG time).

I tried HobbyKing (Bob Smith) EPO glue for some construction and for hinging; it worked fine for construction, but the glue hinges kept cracking and breaking. So I replaced them with Foam-Tac and they seem just fine.

Thank you, Leadfeather, that was a fun project for this long-time balsa builder!

CD
Latest blog entry: BluFO review by Jim T Graham
Mar 11, 2017, 06:23 AM
Registered User
Why didn't I ask Coreman, rather than risk having the elevons fall off on the maiden!

If anyone would know, it'd be the guy who sells planes using glue hinges!

CD
Mar 11, 2017, 06:26 PM
Kit Manufacturer
coreman's Avatar
Quote:
Originally Posted by Captain Dunsel
Why didn't I ask Coreman, rather than risk having the elevons fall off on the maiden!

If anyone would know, it'd be the guy who sells planes using glue hinges!

CD
I have had customers come to me asking about the glue or having used it because it is cheaper but it just doesn't work. I thought that maybe it was too heavy an application but I was unable to get it to work. Sorry Bill
Latest blog entry: BluFO review by Jim T Graham
Mar 13, 2017, 04:51 PM
Registered User
Charlee's Avatar

Form-Cure


This has always been on the BSI website:

FOAM-CURE™ works with all foams, and will actually bond most other materials. It will bond wood and plastic to foam, and is a good canopy glue. FOAM-CURE™ does not, however, cure flexible enough to act as a hinge for aircraft control surfaces.
Mar 15, 2017, 08:27 AM
Registered User
Quote:
Originally Posted by Captain Dunsel
Hi, Rob!

About 15-16 years ago, I started making models with foam turtledecks, etc., in addition to foam wings. For belly-landers, foam worked fine..on grass. I glassed the foam with Polycrylic and painted the planes with plastic model paints. Then we lost our grass strip and had to fly off gravel. No way a belly-lander would survive that, so I went back to just wood (one reason I sold the foam corer).

Micki and I moved to a new home in 2015 and joined a new club (NJ Pine Barons). Their field is about a 5 minute drive from us and is GRASS! So, I'm going back to foam! I just read Keith Sparks' book (learned stuff, even after over 45 years of R/C flying!) and am trying to decide on what projects I want to tackle. I really like the ability to do compound curves, without major woodwork! I do plan to do a test & learn project, before I tackle something more complex!

BTW, hopefully, this won't be a 'miss' year for us and JCSF (every other year seems to be the jinx!). Plus, we plan to be at LeHigh this year (with the beagles!).

Bill
Keith's book is a fantastic resource. I just recently re-read it again and was planning to do some foam work this winter, but got sidetracked. However I did pick up a spool of nichrome wire and was planning to make up a few bows. It's great to be able to work with different mediums

Looking forward to catching up with you, Micki, and the girls soon. Are you planning to come up to Warwick in June?

Thanks!

Rob
Mar 16, 2017, 07:56 AM
Registered User
Coreman, No reason to apologize!. I got all gung ho on the idea of building more foamies (now that we have a grass runway) and started experimenting on my own. I should've thought about asking you (for those of you who don't know, RA Cores is very responsive to customer inputs).

Charles, thank you for the info. I spotted the glue as I was looking at the HK website for motors, etc., and recognized the Bob Smith container. The stuff does work okay on many other things (such as laminating foam for the canopy of my latest, mainly balsa model). BSI glue is also available at my local hobby shop, whilst Foam-Tac is strictly mail-order.

Rob, I doubt we'll be at Warwick. We plan to go on some bike/camping trips, including Kitty Hawk (Micki wants to try hang gliding!) about the time of Warwick.

Yes, Keith Sparks' book is full of good info! Changing clubs wasn't planned, otherwise I wouldn't have sold off my foam corer. I've started picking up the supplies to build a new corer and foam jigsaw. Happily, I have an ancient Sears battery charger that works well with a dimmer switch as a power supply, so I don't have to replace that. Once I finish the balsa model I'm building (a tail-dragger descendant of the Brit-marked model I had at JCSF 2016), I plan to start working on an (almost) all-foam design. Just haven't decided what to draw!

Bill
Mar 17, 2017, 06:06 AM
Kit Manufacturer
coreman's Avatar
Quote:
Originally Posted by stangrob
Keith's book is a fantastic resource. I just recently re-read it again and was planning to do some foam work this winter, but got sidetracked. However I did pick up a spool of nichrome wire and was planning to make up a few bows. It's great to be able to work with different mediums

Looking forward to catching up with you, Micki, and the girls soon. Are you planning to come up to Warwick in June?

Thanks!

Rob
Rob,

Try uncoated braided C/L steel flying wires. That is all I use now. You can tension it up real good and they don't deform like nichrome. I did an article on low cost foam cutting in R/C Soaring Digest back in the 1990s http://www.racores.com/RCSD_articles.html
Latest blog entry: BluFO review by Jim T Graham
Mar 17, 2017, 09:29 AM
Registered User
Jim, Tower has Sullivan CL .018 braided line, in 60 and 70 ft. lengths. Is that good size for coring? I cut cores with an old "Hands-Off" brand corer for almost 30 years, but I always used the nichome wire that came with it and never had to replace it (to be honest, I rarely cut more than two or three models' worth of cores a year).

BTW, Unless I missed something, the 70' length is $3 less than the 60' -- maybe because more people fly 60' and the line ends have eyelets already attached?

There's a very interesting build thread on the Flite Test forum, where a guy's building a Bugatti racer from pink foam. I've picked up a lot of ideas from that thread (Mad Builder's forum, to be more exact).

CD

p.s. I feel like a bit uncomfortable on Flite Test, after the way they lambasted Tom and NEAT, so I keep a very low profile.
Mar 18, 2017, 08:49 AM
Kit Manufacturer
coreman's Avatar
Yeah, the NEAT incident and them going all commercial after their modest, low cost start have put me off. I'm glad they are doing well and wish them no ill will but I'm not going to be involved. I never wanted to go vend at FliteFest as I didn't see the point in a ton of potential customers looking to build on the cheap. I know they screwed another vendor that was working closely with them initially. I know they have done a lot for the hobby and got a lot of people involved, I just have some issues with other aspects. ENOUGH!

I use .017 so yes, that should work fine. The big thing is making sure it's uncoated. I know at one point they started putting a plastic on them to keep them from rusting. Not good for cutting. I like them because I have my bows set up to put almost 100 pounds of pull tension on the wire to minimize wire sag while cutting. At those tensions nichrome deforms and stretches. I use an H shaped bow with a screen door spring across the opposite end from the cutting wire with one arm able to pivot. With the nichrome (and stainless steel fishing leader) I would get at most 10 cuts before I had to replace the wire. For low volume that might be acceptable. but still you can't tension the wire so you get more sag. As I said in the article, I cut from the leading edge to the trailing edge because the sag increases as you cut since the wire cools as you go and the leading edge tends to be the more complex curve while the back half of the airfoil/trailing edge is pretty flat

Quote:
Originally Posted by Captain Dunsel
Jim, Tower has Sullivan CL .018 braided line, in 60 and 70 ft. lengths. Is that good size for coring? I cut cores with an old "Hands-Off" brand corer for almost 30 years, but I always used the nichome wire that came with it and never had to replace it (to be honest, I rarely cut more than two or three models' worth of cores a year).

BTW, Unless I missed something, the 70' length is $3 less than the 60' -- maybe because more people fly 60' and the line ends have eyelets already attached?

There's a very interesting build thread on the Flite Test forum, where a guy's building a Bugatti racer from pink foam. I've picked up a lot of ideas from that thread (Mad Builder's forum, to be more exact).

CD

p.s. I feel like a bit uncomfortable on Flite Test, after the way they lambasted Tom and NEAT, so I keep a very low profile.
Latest blog entry: BluFO review by Jim T Graham
Mar 18, 2017, 10:30 AM
Registered User
Thanks Jim for the tip on using the C/L wire instead of nichrome - I've heard the nichrome wire can be fragile. And I appreciate the link to your article - I'm going to read that over lunch

Rob
Mar 20, 2017, 09:30 AM
Kit Manufacturer
coreman's Avatar
Quote:
Originally Posted by stangrob
Thanks Jim for the tip on using the C/L wire instead of nichrome - I've heard the nichrome wire can be fragile. And I appreciate the link to your article - I'm going to read that over lunch

Rob
Yeah, it's only 23 years old Getting super wire tension is a huge plus on avoiding wire sag and cupping midpoints out of the middle of the core. Especially when combined with front to back cuts
Latest blog entry: BluFO review by Jim T Graham
Mar 25, 2017, 07:51 PM
Registered User
The wire came in yesterday, and it doesn't seem to have any coating.

I won't start building the foam cutting tools until I finish the plane now on my workbench. Then, I plan to do some test cuts before I start on a small (~ 288 sq. inch) model (which I haven't even begun to draw, yet).

Regarding the little delta, it's still unflown due to weather (mainly wind).

CD


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