Larry3215

That looks great!

Its close to what I did on my original heat formed version.

I keep meaning to add another fuse to the one Im flying, but never seem to get around to doing it!

Larry

leadfeather

Larry,

Some thinking out loud for discussion:

What if the two center panels were made from 1/2 blue foam to stiffen the wing up? Fin, elevons, outer wings still made from 1/4 depron or bluecor. I'm thinking it may be easy to make this way and there may be little if any weight penalty if you eliminate some of the other bits now used to add stiffness?

Do the sponsons need to stick out as far as they do? When I watch the video, the front half never comes close to the water.

Larry3215

I dont think there is any real need for the sponsons to stick out that far. Its an esthetic thing more than anything else.

As far as going to 1/2" blue foam for the center panels. Im not sure.

Ive havent worked much with the blue foam. I know its pretty stiff but I dont know how well it would hold up to the bending stresses the the center joint would have to take if you eliminated the under brace.

As the design stands now, a really hard landing will crack the 6mm foam on either side of that joint where the center brace glues on. Even running on rough ground in cold weather can crack the joint.

If you didnt have the center under brace the forces acting on the cneter joint at the top of the V would be several time stronger because of the leverage effect.

Keep in mind, that center section has to resist the bending forces created by the weight of the entire plane when ever you hit the ground. The center under brace reduces the leverage on the joints and spreads the bending forces over 2 joints instead of a single center joint. The under brace also changes the forces acting on the center joint to compression forces instead of tension forces.

On the other hand - it would be simple enough to do test glue up of some 1/2" blue foam if you have any and see how it hold up.

The 1/2" blue foam would certainly be stiffer in twisting.

I would be tempted to keep the same construction techniques that Im using now, but make a 200% - 300% sized version out of the 1/2 blue foam. Say 4 or 5 feet long by 3 or 4 feet wide

That would be cool

Larry

leadfeather

Larry,

I agree, bigger is always cooler!

I have worked with the 1/2" blue foam. It is several times stiffer than the 1/4" bluecor or 5 mm depron. It doesn't have the skins so it doesn't weigh a lot more than 6 mm depron. You can also sand the LE round fairly easily.

It would make a very torsionally stiff wing. A simpletension style crossbrace similar to the flying W's could take up the landing loads. The stuff is pretty cheap, and widely available. $9 for a 4 x 8 foot sheet at Lowes.

Larry3215

Its that cheep? hmmmmm

Ive been considering a few different large foamie projects (big bipe and jumbo flat foamie) that just might work with 1/2 blue foam - especially if its that cheep!

Thanks for the tip!

Yeah, if you kept the bottom center brace peice I dont see why it wouldnt work.

Larry

leadfeather

The 1/2" stuff is nice to work with. Just as flat as depron, sands pretty easily, and it is cheap. Still thin enough cut with a utility knife. It is also thick enough to flush mount servos.

The biggest plane I've built with this stuff was a 40" span delta. It didn't need any reinforcing except strapping tape spar caps top and bottom.

I think I'm going to give it a try on the center wing panels on my Capricorn.

The Cap isn't the sexiest looking hydro, but it sure seems to be the best flying hydro .

Crashalott

Hmmmnnn, very interesting.
I wonder if Home Depot carries this stuff. I know they have pink.

Larry3215

I agree - very interesting!

Im gonna pick up a sheet.

My giant 84" span foamie keeps getting delayed. Its a long complex build and will take a good bit of time to finish - probably all winter at this rate.

I feel the neeeeeed for a big plane at the moment because my 30% Yak is also down for expensive repairs - easy to do but $$.

A 60"-72" span flat foamie would be a nice fill-in and a fast build. I already have the power system and servos that would work sitting around waiting.....

hmmmmmm

Larry

boberos

Extending the underwing ribs aft of the sponsons adds to the yaw stability & on the water they get the model "on the step" almost instantly.
IMO, they are a worthwhile addition.
Bob

leadfeather

Larry,

Would a curved center brace help relieve the shock load and subsequent cracking due to hard landings?

Crashalott

How about some packing tape on the stress area? Mine has 2 cracks in it now which i have hot glued and reinforced with packing tape.
I will let you know how it holds up.

Larry3215

It might. It would be a lot more trouble and might reduce some of the twist resistance it gives when its straight. That triangle that it forms in the center seems to add a lot to the twisting/stifness. Remove the rigidity and you will loose some of that.

You will also have no/less room to hide Rx and batteries etc in that space.

Still, might be worth playing with.

You have been running in the snow? That agravates the problem because the Depron gets a lot more brittle when its really cold. Packed snow is also not as forgiving/soft as water by a long shot. It can actually be pretty rough to run on going over small bumps etc.

Id bet packing tape would help, but not sure how much.

Ive had the best luck using 1/2 oz glass cloth wraped around the leading edge and back about 1" on the top side and 4 inches back on the bottom - applied with water based Polyurethane. I cut a piece about 3"-4" wide x 5 or 6 inches long and use one on each joint.

Havent cracked that joint since I started doing that. Now I have to hit really really hard and it breaks at the outboard edge where the glass stops

Thats only happend once when I badly misjudged a super low loop and tried to fly about 6" under ground. Didnt work too well. Cracked one side panel part way thru and stripped both elevator servos! Actually I think the loop went bad because I had already stripped out one servo earlier in the flight by trying to fly 1/2" under ground. Ive gotten away with that about 2 out of 3 times

Larry

Larry3215

Hi Bob!

You got yours finished? I dont remember seeing it (probably did and just have mind fade) before I deleted all my stuff from the old thread and got kicked off RCG.

Post some pics if you have any.

Larry

Larry3215

On 1/2" Blue Foam.

My local Home Depot computer shows they have 136 in stock but none on the shelf. Now I have to try some others. Dont trust them if you call and ask - they have no clue...

Larry

leadfeather

In my area HD carries the pink foams and Lowes carries the blue foam.

I just made templates for my build. This is a big aircraft. It is amazing that it flies well with only 100 watts!

Larry3215

Low wing loading is the key

Post some pics when you get started!


Im still not finding any 1/2" blue or pink in my area - Washington state - even at Lowes. Lots of 1" pink and blue tho. Im going to make some more calls tomorrow.

Larry

Crashalott

I am wondering how it would be to make one out of bluecore fanfold foam and double everything up. I know it would be a little heavier but i think it would still fly ok.

Larry3215

I think that would work fine.

Id bet you could probably scale it down some - 75% maybe - and get by with a single layer and the same details as normal.

Infact, Im pretty sure someone did a fanfold version early on that was a little smaller. It may have even been glow powered IIRC

Larry

leadfeather

For my build I'm using 1/2" foam for the two center wing panels and 1/4" blue core for the outer wing panels, the fin, controls surfaces, and reinforcements.

Larry3215

There is no 1/2" blue or pink foam anywhere close to me. I got some 1" blue to play with.

I did find out that the blue is styrofoam and the pink is the cyanosomething? stuff.

That means that the blue would be relatively safe to cut with a hot wire, but the pink will put out very very nasty fumes.

Now to decide what to build.....

Larry

Larry3215

My next project....

http://www.wattflyer.com/forums/show...025#post320025

Larry

Larry3215

I just found some new Gorilla glue.

It looks clear in the bottle and says "Quick Cure/Dries White".

I just tried some and it does dry faster and ends up white.

The bottle is much easier to work with than the Sumo glue too.

I like it a lot so far.

Larry

boberos

hi Larry,

Sure did get it finished & flew it all summer.
Works great. The only mod I did was to add a bamboo skewer to keep the centre joint from breaking.
I tried to up load pics but couldn't do it. Wattflyer not too user friendly for adding pics.

Bob

leadfeather

Larry,

The bottom center reinforcing strip seems like a very good place to mount the battery. Lots of adjustment available by mounting it underneath. Are there any issues with the battery if it gets wet?

Larry3215

The pics need to be under a certain size depending on what type of file it is. Scroll down to the bottom of the upload page and it gives the max sizes for the various types.

jpg I think can be pretty large, but some others have to be fairly small.

I have some software that re-sizes pics to make it easier to post them.

Larry