1.3 or 1.9?

[BTCat]

I'm about to push the button on a foam order and am thinking about getting 1.9 instead of 1.3. What are the thoughts on this? Kent, I know you have been using 1.9 on some of your stuff. Maybe others. I am looking at stuff like a Yak or Edge build. Not sure if it will be too heavy for that.

[akent]

I really don't know what to tell you, BT.

The 1.9 stuff is heavier, but also considerably stiffer. You need less CF with this foam.

The only thing I've built out of both is the F-22. These are completely different animals. The fast one made from 1.9 is too heavy to hover and do high alpha very well at all. But it's fast! The light one made from 1.3 is a high alpha animal. I know the power system on the fast one is heavier too. I also added just as much CF to the fast one as the light one.

I think it boils down to what you want to build. If you want speed, then the heavier stuff will work better. If you want 3d and/or slow flying, then the lighter stuff would fit. Lighter also means less power needed to do 3d, so lighter running gear, smaller batteries, etc.

The 1.9 also doesn't seem to tear as easily. I find myself twisting around the 1.3 stuff on my other planes to find any tears. Then just some hot melt or Welders and it's as good as new. I haven't had any tears yet on the 1.9 F-22 and I have flown it a lot.

With my 1.3 Yak, it does NOT like much wind at all. It is relatively floppy. I would like to build one from 1.9 just to see how it compares, especially in a little wind. Mine hovers nicely with the 2730-1300 motor. I don't know how well it would if it were several ounces heavier.
Kent

[19000rpm]

I think the advantages of the 1.9 out weigh ;D, pun intended, the 1.3. The only thing is you'll need is a bit more power, maybe one size longer prop, if the model was designed for 1.3.

[BTCat]

Maybe I'll just buy some of each. Not sure yet.

[akent]

Ok. I am an idiot for not doing this before.
I have both foams here, both in the large sheet size, 24" x 36".

I just weighed them all.

Entire sheet weights:
1.3# white: 3.2 ounces, for 0.53 ounce per square foot, or 15 grams per square foot.
1.9# white: 5.0 ounces, for 0.83 ounce per square foot, or 23.5 grams per square foot.
1.9# black: 5.9 ounces, for 0.98 ounce per square foot, or 27.8 grams per square foot!!

Humm, the black is considerably heavier! I never would have guessed that! I like the black stuff! It looks good in contrast to painted white stuff.

In some ways that is a lot of difference. In other ways, trivial.
Kent

[akent]

Someone needs to go into the foam making business.
We want the rigidity of Depron with the untearability of a FedEx bag.

[Solitaire]

So, we've added another category to the list of foams?
EPP
EPS
EPO
Depron
FanFold
BluCor
FedEx Bag

;D

[BTCat]

"FedEx Bag" - I gave my former wife a candy bar.

[19000rpm]

May 3, 2010 18:37:21 GMT -6 akent said:

Ok. I am an idiot for not doing this before.
I have both foams here, both in the large sheet size, 24" x 36".

I just weighed them all.

Entire sheet weights:
1.3# white: 3.2 ounces, for 0.53 ounce per square foot, or 15 grams per square foot.
1.9# white: 5.0 ounces, for 0.83 ounce per square foot, or 23.5 grams per square foot.
1.9# black: 5.9 ounces, for 0.98 ounce per square foot, or 27.8 grams per square foot!!

Humm, the black is considerably heavier! I never would have guessed that! I like the black stuff! It looks good in contrast to painted white stuff.

In some ways that is a lot of difference. In other ways, trivial.
Kent

Good stuff Kent.

The difference in the 1.9, white vs. black. might be due to the substance they add for making the black color.

Another factor in the built plane is the weight of the paint used. Since EPP soaks up paint like a sponge that has to have a significant contribution to AUW. The paint also seems to stiffen the EPP so it becomes a bonus structural factor.

What about laminating depron with EPP? HMMM

As long as we have a fantasy foam going why not make it as light as a sheet of typing paper too. ;D

[akent]

Yep, all that makes perfect sense, 19k.

Hey I like that light foam idea too!

[BTCat]

RCFoam.com sells by the sheet at reasonable prices. I bought some 1.3 and 1.9. I even loaded up on some CF while I was at it. I should have a working hot wire soon. I have everything available. I just haven't had time to do anything with it.

[akent]

Wow, BT, that is a great place for foam and they have great prices!

I also really look forward to your hot wire machine!

Thanks!
Kent

[19000rpm]

2X's dat BT.

[BTCat]

Well, 4 days and my foam and CF order is here. Couldn't get any better than that. I ordered 3 sheets of 9mm 1.3 at 36x24, one sheet of 9mm 1.9 and one sheet of 6mm 1.3. They threw in a free 6mm. One issue is I can't tell the 1.3 from the 1.9. I weighed it and it all comes out about the same -- about 107 to 109 grams. I honestly think I might have gotten 4 1.3 sheets.

I sent an email to them about it. I am otherwise very pleased with the price, service and delivery time.

Still no time to make the hot wire stand...

[19000rpm]

That's great BT. I'm wondering if they might have indicated which weight it should be on a packing slip? Not that it would make any difference if they sent the wrong weight unless that's why you got a free sheet of 6mm. Anyway, the prices are sure good.