CHELLIE

Hi Larry Do you think if adding 2 CF tubes the width of the hydro on the front and back would help with the flexing ? just a thought, Take Care, Chellie

RocketMan

I picked up some CF rods of various sizes at the LHS to use for the control linkages and I was wondering the same thing if they would also work to stiffen the structure if they were glued into the foam. I have no idea what size rod would be best for this purpose however. Or would you need an actual CF hollow tube to get the strength without too much weight?

I think I am going to stick with the extra pieces of depron for this first attempt however :-)

Cheers,

Rick

Larry3215

Yeah, the one on the end is a lrager size I tried as an experiment. It was too floppy/twisty tho and I didnt like the way it flew as much as the smaller ones.

I forget the exact dimensions. I think the outer panels were 8"wide and the center panels 10" wide and the length increased to 33" not counting controll surfaces.

That size - or even larger would be doable but you'd have to do more reinforcement to stifen thngs up some more - wider center brace, doubled up front edge or adding carbin rods.

The 6mm Depron can only stretch so far unsuported befor it starts flexing so much you have less and less controll over where it goes

Ive been thinking of doing a GIANT scale version - maybe 72" long and 48" span. Thats the largest that would fit in my truck. Probably use a different foam board or do a built up wing structure of some type if I did that. Im thnking power it with a larger outrunner. It would be impressive on the water!

Larry

Larry

Larry3215

That would add a lot of strength, but I would'nt use tubes and Id only do the front edge. Tubes are tooooo stiff and tend to break instead of bend.

Some 2mm rod on this 3mm version would probably be about right. If I do it, I will only add them to the front leading edge.

The motor and battery will both be sitting right at the front edge so thats where all the weight is concentrated and where you need the strength on a hard landing. Even in bad dumb thumb crashes Ive never had one break at the rear. It aalways the front that goes first.

Im going to try it first with no carbon just because Im stuborn

Larry

Larry3215

I dont like using hollow tubes in this situation. The structure needs to be able to flex or it wont last long. On the 6MM version I think 2.5mm or 3MM rod would be fine.

I still prefer the doubled front edge because it serves a dual purpose - it reduces the wing twist and helps roll rate at the same time.

If you do use carbon - remember I dont have any really good reason NOT to - it needs to be at the front as I mentioned befor. Thats where most of the weight is going to be carried.

Larry

Larry3215

Some more pics

These sponsons are smaller - 1.25 wide x 2.5 tall and they are made from EPS (styrofoam) because its lighter and I had some laying around I just hacked them roughly to shape with a kitchen knife then sanded roughly with some 50 grit then 150 then a dusting of paint.

They wont be as durable as the pink foam but thats ok. Im probably going to glass the bottoms with .5oz glass and water based varathane.

If I get lazy or dont get it done in time for tomorrows indoor session, I'll just use some clear packing tape on the bottoms.

I also put a bit of paint on the top of the rudder. I wont do much more paint - maybe a stripe on the wing tips - as it adds a lot of weight.

Larry

Larry3215

Oops! Here is another "tip" I forgot to mention - sorry!

Its a good idea to pre-bevel the trailing edges of the 4 wing parts before you glue them together into the 'W' shape.

It is a lot easier than doing it after wards - like I am haveing to do now!

Larry

Larry3215

Its all done and even test flown - if un-intentionally!

Got it all finished and ofcourse its pitch dark outside. All I have is a small porch light to see by - no street lights in my back woods area, but I wanted to do some taxi tests and see if the motor had enough pull on 2S to get it going.

I have NOT finished the bottoms of the sponsons yet. They are just the raw foam. Turns out raw styrofoam is not very slippery on an asphalt driveway. I had to use a lot of power just to get it to move, but I taxied down the drive and then turned around to go up hill. I had to goose it pretty good and >>>>>>>>>> off it went into the dark!

I think I almost got it stuck in a tree before I got it turned around and headed back. Im not sure because it was mostly invisible in the dark when my eyes turned away from the light!

Luckily, it glids very well even when you cant see it so the CG must be fairly close

Its back in one piece - except where the asphalt has worn down the sponsons some.

Whew!

Off to cover the bottoms of the sponsons with some glass.

Larry

Larry3215

Forgot the stats. I did NOT make my goal of 1 oz/foot. Didnt even come close actually. It ended up at a smidge over 2 oz/ft.

Not a lot better than the bigger 6mm version at 2.5 oz/ft!

All up weight with a 2S TP 1320 pack is 290 grams = 10.23 ounces.

Total wing area is aprox 724 sq inches or a hair over 5 sq ft.

Im not sure its worth the trouble. Building with the 3mm is not as easy as the 6mm. Its a lot more fragile and tends to bend and warp easier and is harder to keep straight as you glue things up.

I also think my rudder is not going to last long. I like BIG rudders - especially on this model, but I think I made this one too big. Its awefully big and floppy when made from 3mm. I had to add some carbon (darn it!) to stiffen it up as it was just too floppy.

On the plus side - it is smaller and will fit in the truck a little better with other models. It also wont be quite so intimidating to other flyers in the small indoor space we fly at.

Still, its not that much smaller. I tink if I do another small one it will be even smaller yet. That will make it stronger and easier to work with and should end up at the same wing loading as the larger version - which is plenty low enough for small space flying anyway.

Larry

Larry3215

Here are the final set of build pics. Most all of these details carry over to the big version, but ask any questions if anything isnt clear

Larry

3D52

Larry, it looks like the small one has right thrust but no up thrust. Is that correct? I think I'm going to build one out of 9mm EPP and see how it goes, its pretty flimsy but not as bad as 3mm dupron.
Steve

Larry3215

Good eye!

Yes, they both have some right thrust and the larger version has 3 or 4 degrees of UP thrust built into the motor mount.

That UP thrust is needed because the motor is mounted well above the center of drag.

On the smaller one, the thrust line is a lot closer to the center of drag, so I took out the up thrust. Im hopeing my guestimate os close

Im off to our first indoor session of the year shortly, so I will get to fly it then.

I wanted to do some more outdoor testing/trimming first but its extreemly windy today so I'll have to do that in a small space indoors.

Good luck on the EPP version! It will be interesting to see how that works out. It willbe very durrable for sure

As I mentioned before, twisting of the main wing section can be a problem that causes aileron reversal tendancies. You may need some extra bracing but maybe not. Ive never worked with the 9mm epp so it may be just fine.

Larry

Larry3215

The indoor went about as I expected - the little one flys pretty much just like the bigger version but is more fragile. I misjudged a loop and hi the floor pretty hard and cracked it right where it always does - along the join line on the under brace.

On the plus side it feels a little easier to handle in the small space.

Lowering the motor height caused more of a change than I expected in the thrust line. I think Im going to have to add some DOWN thrust.

I wont make that decision untill I get a chance to fly it outdoors and do some more trimming flights. I need to get the CG right befor I mess with the thrust angle. I think the CG needs to go back more too, but I need some more room to test that properly. Our indoor space is just too small to allow for proper trimming. Your constantly turning to miss the walls!

Over all - next time, if I want a smaller one in this size range I'll stick with 6mm. If I went down to a 60% size or smaller, then 3mm would make sense.

Larry

Larry3215

Jed sent me some shots of how he is doing his Flying W version.

Larry

Larry3215

More pics

Larry

rc808

I'm thinking about a 1/2 scale version of this. I cut everything out of 3mm depron. I wish i had some epp to do this with but i don't. Would one of those 10 gram motors from uh be enough to power this or go with the 24? It's not that important that it runs on the water as i have no water calm enough nearby. Just looking for the ability to take off from a baseball field. Thanks for any advice.

Larry3215

That 10 gm motor might be enough to fly on, but I doubt it would be good for tooling around on grass and maybe not enough on pavement.

Id go with the 24 gm motor and a small 3S pack. Make sure the bottoms of your sponsons are slick and I think it will work fine

Keep us posted on results!

Larry

Larry3215

An up-date.

I glassed over the front 2" of the bottom center brace joints on the bottom side and lapped the glass around onto the top side some. I used .5 oz cloth and wtaer based Varathane.

I think I mentioned before that I had glassed the bottoms of the sponsons the same way. I think the glass will be tough enough for indoor flying on polished floors or on grass, but not for outdoor use. I did some outdoor flying yesterday and today on pavement and rough gravely dirt and I can allready see wear. I'll have to re-do it with plastic if I keep that up.

I also got to do a but of water flying at my favorite mud puddle! It does just fine I even did some tail touches in the water which looks cool. I think the little one is a bit more stable in hi alpha harrier than the big one.

Also got to do some trimming flights. I think the thrust line is fine. The CG just needed to go back a good ways. Im almost perfect now.

I really like the look of having all the waires run under the deck so I re-did the big one the same way. I left the servos mounted sideways but hid all the wiring and mounted the pack on the bottom in a cut out section. The traingular hole under the center is not deep enough for a 3S 1320 pack as is. If you considering doing the same thing Id make that center brace wider - maybe 4-4.25". It should make things stiffer and stronger too.

More pics below

Larry

Larry3215

Check out page 187 of the new Model Aviation mag.

My buddy Jed's Flying W version got a writeup and picture by our local AMA district rep

Larry

Larry3215

Got to do a short flight in the snow today. What a hoot! I'll have some (probably very bad) video up shortly.

OK, I think the video is working now...

Larry

Larry3215

video seems to be working now..

RocketMan

That was great Larry! The Capricorn could really put the fun back into winter :-) I've collected all the materials and I am hoping to start on mine around the middle of December when i get back from the 3 week business trip that I am currently in the middle of. Hopefully we will have some snow by then for the maiden. Sheesh, I can't believe I'm hoping for snow!

RM

Larry3215

Flying off snow isnt quite as much fun as water but its close. Its for sure a lot colder! The huge advantage snow has over water is that you can walk out to recover the plane if there is a mishap. On water you need a boat

I was pleased at how well it does the speed skater turns on one pontune. Those are one of my favorite moves.

Keep in mind that Depron get more brittle when its really cold. The parts on the jet that crashed shattered rather than the usual bending you get on warmer days. On the plus side its actually easier to do the repairs.

Larry
Larry

Larry3215

Jed sent me some more detail shots of his setup.

Larry

Larry3215

I posted this in the Jet build thread but it bears repeating here too....

There are several things to be carefull of when flying in cold and especially in snow.

Cold makes the Depron more brittle, as I said, so things break easier but its not all that bad as long as you dont crash

The main issue you will have in cold weather is the batteries. They will act like they have a reduced capacity and run at lower voltages and in general just not put out as well when they are cold.

Flight times will be reduced and power levels will be lower. It will feel like your packs are half dead if its very cold.

Its best to NOT push them as hard either when its cold. Its also a good idea to warm the packs up before you re-charge. I have heard some reports that its possible to over charge a cold pack.

I havent had any servo issues in cold weather but I suppose you could have problems if the gear lube got stiff or if there was moisture inside that froze. I havent flown in much below freezing temps. I break down before the planes do!

You have to treat snow just like water as far as water proofing. Snow will melt all over things and water WILL get into anything so treat with CorrosionX as if you were going swimming.

You couldnt see it in the video but wheels dont work so well on snow The Capricorn did fine because it has ski's in the form of the sponsons.

If you crash into a snow bank or in some way get snow packed into the motor, it could cause cooling problems if it blocks the air flow. It could even prevent the motor from spinning when you power up and burn out the esc or motor so be aware of that. I can see snow/ice mucking up gear boxes too.

Other than those small issues... its a hoot!

Larry