SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Oct 08, 2004, 07:05 AM
jean-claude Terrettaz
bidule's Avatar
Carp, Ontario, Canada
Joined Mar 2000
1,459 Posts
Be carefull with Sirius, few years ago with a 27 cells setup, the wing jonction @ the fuselage brake in a turn .
Once Keith SHaw said : buy cheap buy twice!!!
Just spent the money on very good plane . The only part easy to do is the fuselage , the wing can be in foam like the LEA 3 . I build a 10 cells wing who last, and was OK for training....
bidule is online now Find More Posts by bidule
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 08, 2004, 08:15 AM
BANNED!!!
soholingo's Avatar
Laurel, MD
Joined May 2001
12,686 Posts
Laugh and mock if you must... but I said nothing about a state of the art competition F5b. I said a molded f5b plane. I am aware of the cost of the carbon, and maybe a few years from now I will be building planes worthy of competition. I am speaking of building a plane like the sirius for now.

I don't know why I still mention this stuff in these forums...
soholingo is offline Find More Posts by soholingo
Reply With Quote
Old Oct 08, 2004, 12:57 PM
Registered User
Erez-E's Avatar
CT, USA
Joined Feb 2002
211 Posts
Composite materials are really not that expensive. At our scales, construction technique is much more important than the material. You could get away with using mostly glass, with some carbon and kevlar reinforcment. I buy from www.fiberlay.com, and on a per plane basis, for the fiber, resin, wax, pigment, and bagging, I don't see it being more than $100. Glass is really quite cheap.
Erez-E is offline Find More Posts by Erez-E
Reply With Quote
Old Oct 08, 2004, 01:13 PM
f5b-uk
Mike Seale's Avatar
United Kingdom, Dorset
Joined May 2002
3,065 Posts
Quote:
Originally Posted by soholingo
I don't know why I still mention this stuff in these forums...
Because you know you're right! Maybe not $50, but probably not $200 either. Remember, Marcus, you're building to World Championship standards for some of the best pilots in the world. And I'm sure you pay a lot more for your paint schemes than anyone else

Over here a lone UK pilot rented the Raketenwaum moulds and learned to make his own airframes to an excellent/world class standard in just 12 months - first attempts flying in only a few months. He's now going to have a company mill his own design for next season. It's not cheap BUT it could have been if a few interested modellers lived close together and were able to learn the skills and share the costs.

Like you, Jay, I do not understand why there is no USA F5B airframe available to the masses. The only one I know is the Verminator, but this is/was Thomas Pils' personal extravagence - never meant to be a commercial venture.

If you are going to go it alone you have to accept that you'll wave goodbye to a few thousand bucks before you see a decent model. IOW, you could buy a few S11's - OR - make your own. I decided that I didn't have the time, the skill, the money or the space to make my own any more.

Mike
Mike Seale is online now Find More Posts by Mike Seale
Last edited by Mike Seale; Oct 08, 2004 at 01:19 PM.
Reply With Quote
Old Oct 08, 2004, 01:21 PM
Registered User
davidfee's Avatar
San Diego, CA, USA
Joined Mar 2001
3,068 Posts
Glass is also not stiff, light or durable enough for competition use. I know Jay clarified that he is not talking about building competition planes right away, but fuselages take a lot of abuse and glass tends to crack a lot on those spot landings. The airplanes have evolved over the years and things are done the way they are for good reason.

As a good friend says, "Time to fire the engineers and start production."

-David
davidfee is offline Find More Posts by davidfee
Reply With Quote
Old Oct 08, 2004, 01:23 PM
Registered User
WimH's Avatar
Belgium, Flemish Region, Oosterzele
Joined Dec 2001
5,451 Posts
Quote:
Originally Posted by soholingo

I don't know why I still mention this stuff in these forums...
Are you familiar with the term masochism?

As for the Sirius, I've seen several, none broke in the air. I've seen Surprise 6 and Lea 3 or 4 break in the air. As I said before, the only way to be sure of an unbreakable one is to build it yourself and make no mistakes. If you buy one, you'll never be sure.... You cannot judge the quality by just one example....
WimH is offline Find More Posts by WimH
RCG Plus Member
Latest blog entry: That elusive thermal...
Reply With Quote
Old Oct 08, 2004, 01:27 PM
f5b-uk
Mike Seale's Avatar
United Kingdom, Dorset
Joined May 2002
3,065 Posts
Quote:
Originally Posted by WimH
As for the Sirius, I've seen several, none broke in the air. I've seen Surprise 6 and Lea 3 or 4 break in the air. As I said before, the only way to be sure of an unbreakable one is to build it yourself and make no mistakes. If you buy one, you'll never be sure.... You cannot judge the quality by just one example....
Exactly. My Sirius still lives, but my Surprise 8 died.

Mike
Mike Seale is online now Find More Posts by Mike Seale
Reply With Quote
Old Oct 08, 2004, 01:34 PM
Registered User
Germany - Stuttgart
Joined Aug 2004
30 Posts
Hello Soholingo,

you are on the right way. Start learning how to build, with cheap material, glass instead of carbon, and start exercising with these ships. It doesn't really matter for exercising, if the plane is 100 gr. heavier or not. To have a chance in competition, you have to get among the 5 best pilots - it's not sufficient to be able to buy the hottest engine or to buy the best plane.

Juergen
Juebie is offline Find More Posts by Juebie
Reply With Quote
Old Oct 08, 2004, 02:35 PM
RCGroups Author
SoarNeck's Avatar
Calgary, Alberta
Joined Nov 2001
1,491 Posts
Quote:
Originally Posted by Mike Seale
Like you, Jay, I do not understand why there is no USA F5B airframe available to the masses. The only one I know is the Verminator, but this is/was Thomas Pils' personal extravagence - never meant to be a commercial venture.
Because of labour costs! I can ALMOST buy that you could build a sport model for $100 in materials (not including epoxy, knife blades, rotary cutter blades, peel ply, etc etc), but who's willing to work for $10/hr?

Say the model costs $400. Take off 10% for profit, and you're down to $360. $100 in material knocks us down to $260, disposables and adhesives probably $20 (in bulk) fpor $240, a cheap box and packing is $40 (w/labour). So, we're left with $200 for labour. Even assuming someone would work for $10/yr (heaven knows why a skilled composite worker would do such a thing), you can't mold a model in 20 hours. Even if you could, who the heck would work for $40 profit?

THAT'S why there's no American sport model. If you ran the same numbers for a competition model with the higher material costs, mold machining, extra skilled labour etc etc, I think you'd run to buy a Surprise or Avionik.

Having sold composite models of my own before, I totally agree that there's no money in it whatsoever.

Take TD/F3J sailplanes. The current hot Euro moldie is the Pike Superior, which can be had for about $1050-1150 US. The only US-made moldie is $1800 US!
SoarNeck is offline Find More Posts by SoarNeck
Last edited by SoarNeck; Oct 08, 2004 at 02:37 PM.
Reply With Quote
Old Oct 08, 2004, 03:16 PM
BANNED!!!
soholingo's Avatar
Laurel, MD
Joined May 2001
12,686 Posts
I am thinking most of the 'time' is spent waiting for the epoxy to cure. Once you have a good setup, I would think the layups would take a few hours, cure, Join the wings, cure. Of course I am oversimplifying...

And for those of you following this I think Marcus' planes are 14oz or so WITH Servos. This sort of quality is only available with the higest quality components. I am aming for 25oz with my first few models, and then hopefully somewhere around 18-19 oz once I become skilled. I have a lot of work to do, and its all spare time work, so it the first model won't be pulled until next year I am sure...

jay
soholingo is offline Find More Posts by soholingo
Reply With Quote
Old Oct 08, 2004, 03:35 PM
RCGroups Author
SoarNeck's Avatar
Calgary, Alberta
Joined Nov 2001
1,491 Posts
Quote:
Originally Posted by soholingo
I am thinking most of the 'time' is spent waiting for the epoxy to cure. Once you have a good setup, I would think the layups would take a few hours, cure, Join the wings, cure. Of course I am oversimplifying...
Yes you are, by quite a bit. Please do us a favour and keep a time record when you decide to try this yourself...I think that's the only way you'll believe the amount of work involved.

But by all means, go for it.
SoarNeck is offline Find More Posts by SoarNeck
Reply With Quote
Old Oct 08, 2004, 03:57 PM
Registered User
sneu's Avatar
United States, CA, San Diego
Joined Dec 1999
7,343 Posts
Quote:
Originally Posted by SoarNeck
Yes you are, by quite a bit. Please do us a favour and keep a time record when you decide to try this yourself...I think that's the only way you'll believe the amount of work involved.

But by all means, go for it.
When we were building our own models it took about 20-25 hours of direct labor per plane. Don't under estimate the amout of time in measuring, cutting material,cleaning,mold prep, painting....etc.

Steve
sneu is offline Find More Posts by sneu
Reply With Quote
Old Oct 08, 2004, 04:06 PM
BANNED!!!
soholingo's Avatar
Laurel, MD
Joined May 2001
12,686 Posts
Quote:
Originally Posted by sneu
When we were building our own models it took about 20-25 hours of direct labor per plane. Don't under estimate the amout of time in measuring, cutting material,cleaning,mold prep, painting....etc.

Steve
Steve that's exactly what I was figuring... There is a lot of time needed for cutting, measuring, remixing the epoxy that's kicked in too early. I appreciate the input...

By the way where are those old molds? Seriously....
soholingo is offline Find More Posts by soholingo
Reply With Quote
Old Oct 08, 2004, 07:17 PM
Registered User
Erez-E's Avatar
CT, USA
Joined Feb 2002
211 Posts
Quote:
Originally Posted by davidfee
As a good friend says, "Time to fire the engineers and start production."
-David
As an engineer, I take offence to that comment. Just for my own edification, I want to see a breakdown of the material cost. I'm not considering molds, pump and whatever else you need to buy once.

So epoxy is what, about 9 lb/gallon? Let's say you've got a 20oz plane and a fiber fill ratio of 60%, so that's 8oz of epoxy. Let's say you waste a bit and use a 16 oz. That's .11 gallons. If the epoxy is about $80 a gallon, including hardner, that comes to $9 worth of epoxy, lets say $10 with shipping.

Wax is relatively free.

Ok, on to the graphite. 3k is about 6oz/yd^2. and about $22/yd^2. So carbon is about $4/oz. 60% of 20oz is 12 oz. soooo that's $48 worth of carbon. You would need say $12 worth of peel ply and breather.

So for an all carbon jobbie, your total cost would be $70, again assuming you have the mold (this is where the problem is), a pump (~$300 for a kit), AND assuming you buy in small quantity.
Erez-E is offline Find More Posts by Erez-E
Reply With Quote
Old Oct 08, 2004, 07:59 PM
Registered User
sneu's Avatar
United States, CA, San Diego
Joined Dec 1999
7,343 Posts
Quote:
Originally Posted by Erez-E
As an engineer, I take offence to that comment. Just for my own edification, I want to see a breakdown of the material cost. I'm not considering molds, pump and whatever else you need to buy once.

So epoxy is what, about 9 lb/gallon? Let's say you've got a 20oz plane and a fiber fill ratio of 60%, so that's 8oz of epoxy. Let's say you waste a bit and use a 16 oz. That's .11 gallons. If the epoxy is about $80 a gallon, including hardner, that comes to $9 worth of epoxy, lets say $10 with shipping.

Wax is relatively free.

Ok, on to the graphite. 3k is about 6oz/yd^2. and about $22/yd^2. So carbon is about $4/oz. 60% of 20oz is 12 oz. soooo that's $48 worth of carbon. You would need say $12 worth of peel ply and breather.

So for an all carbon jobbie, your total cost would be $70, again assuming you have the mold (this is where the problem is), a pump (~$300 for a kit), AND assuming you buy in small quantity.
Not so fast--3 oz carbon costs more like $80-90 sq yd, Kevlar about $20 for the 1.7 oz sq yd nice stuff, high grade carbon tow for the spar caps $100lb, Epoxy that will give long enough working time yet set overnight $100 gallon, Roha Cell $40 for 24/48/.032 inch sheet---etc --etc--etc. The costs go on! Material costs are just the start--you have also to put into the mix the cost of the parts that don't come out of the mold in one piece too.

Steve
sneu is offline Find More Posts by sneu
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion 2007 North American F5B contests/practice soholingo High Performance 116 Jan 06, 2008 11:19 AM
Sold For Sale - Hobby Lobby Graupner North American AT-6 Harvard chadvicki Aircraft - Electric - Airplanes (FS/W) 3 Nov 23, 2006 12:51 PM
North American F5B: A personal retrospective... soholingo High Performance 202 Jul 25, 2005 09:29 AM
2005 F5B NATS (North American Tour Series) ShredAir High Performance 44 Oct 26, 2004 09:08 PM
Best North American source for Hacker brushless motors? ShinySteelRobot Electric Plane Talk 5 Oct 30, 2001 01:38 PM