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[tonyH]

Evenin' All,

I've been planning to build a 1:36 cruiser with a Walrus to be catapulted off. I reckoned that the plane was the key part and so started with that to see whether the whole project was feasible. The photos are of the MkI version which flies like a brick. The span is 15 1/2 inches and power comes from an outrunner. Control is via elevator and ailerons plus the ESC. All up weight is just under 6oz including a 300Mah 2 cell Lipo (20C)

I've come to the conclusion that I don't have the required skills to build light so, would anyone else who knows what they're doing like to try?

I'll be happy to GIVE whoever it is the MkI complete with all the electrics, micro servos, ESC, battery, motor, 4ch Rx plus 3 spare vacformed fuselages to play with ON THE PROVISO THAT the MkII, MkIII or whatever has a fair chance of flight (subject to weather) at the next Mayhem weekend.

Please note that once handed over, I'd have no rights to any of the bits or completed plane. I.e. It would be yours!

Tony

[amdaylight]

I live a little to far away to be of much help other than give a few suggestions and ask a few questions. First are the upper ailerons always up like they are in the photo or are they connected to the lower ones. The reason I ask is that if you are trying to fly it this way the drag from them in the raised position along with the down ward lift would make this plane almost impossible to fly. Next are you planning to land it on the water or on the grass next to you? If on the grass you could save some weight by building the fuselage from  sticks instead of sheet balsa. Next on this kind of project you need to get the very lightest balsa wood you can, bring your own scale to weigh each sheet. Next go looking for some of the small indoor RTF air planes and borrow their servos and stuff. see the photos below, these are photos of the Vapor by Parkzone. Now you might have to use a different reviver and esc but these servos will save you some weight." Remember don't give up the Ship"

Andre Anderson
over yonder in Portland Oregon

[tonyH]

Hi Andre,

Thanks for your input.

The fuselage is vac formed in 0.25mm plastic and the wings are very light balsa with foam uppers and then tissue covered. Internal and external struts are 2mm carbon tubes. Floats and engine
The servos are 5gm each and the Rx and ESC came from Robotbirds so are very light.
The ailerons have not been connected to the lower ones. Trials took place with them fixed flush with the wings. Landing on water would be, of course, ideal but not a 'must have'.

The main problem is that I'm not skilled in working to such light tolerances and never having built planes before I've little idea of what you can get away with.

Tony

[Arrow5]

Tony at that scale forget balsa altogether. Use depron foam as used for pizza trays etc. You must think along the lines of an indoor model that can only be flown outdoors on the calmest of days ie NO wind ! Dont even think of landing on water at that size, it wont be pretty, plus dampness on micro electronics is critical, salt water instant poison. Give me couple of days and I`ll post some links to suitable suppliers. Some concessions to scale might be in order too. I`m sure some of the folk on the indoor model links I will post will take up your offer with relish. My 1/24th scale HMS Invincible has very Stand-off scale Sopwith Pup models and are about 18" span but nobody has said anything when they see them fly. The Sea Harriers and Sea Kings are static "solids" at correct 1/24th. There is a chap from the Bristol area with a similar problem with his large scale (manned model) HMS Hood. I`ll post a link later on his project.

[Arrow5]

Tony , are you saying you are not an aeromodeller ?

[tonyH]

Absobloodylutely right!

What foxes me is, for example, the probability that the props are just not big enough to drive the thing, and so with a pusher what do you do?
I've no idea how many watts drive what weight/size of plane etc. and what size of prop will give you enough Oomph!

That's the sort of basic thing that's the aeronautical version of so many threads on Mayhem!

I'm not trying to pass the buck and it would be fun if a real plane could be catapult launched off a decent size ship and two 'specialists' could make the whole job better.

Tony

[amdaylight]

Tony,

If it were mine I would do away with the upper ailerons and only use the lower ones, add an inch to each side and maybe make the wing from depron as suggested, and have it cambered with a concave underside. Most of my little park flyers only use rudder and elevator with throttle. Add a little more dihedral and you should be good to go.

Remember If we new what we were doing they wouldn't call it "Research and Development"

Andre
over yonder in Portland Oregon

PS
I forgot to attach the photos of the indoor flyer that I mentioned in my other post so here they are.

[Arrow5]

Your first requirement is a competent indoor r/c pilot . It is not a too difficult job. Meanwhile put your efforts into a non flying static display Walrus. Still searching more later.

[Arrow5]

Here you are, based in South Leicester the www.aeronutz.flyer.co.uk is the font of all wisdom regarding very small models and links to suppliers. Post your quest on their site and someone may take up the challenge. Any photos of your ship ?   The other member who is planning a flying aircraft off his Hood is MartinH-K , you should PM him and share your research. Best of luck with the project.

[tonyH]

Hi again Arrow,

Thanks, I'll try Aeronutz since the name suggests an 'off the wall' attitude.
No photos of the ship, apart from the real thing, since the plane is the key component.

Tony

[andyn]

I have quite a lot of experience in this field, and am a competent model flier.

I fly a Shock Flyer, have tried indoors but I built it too light and I put far too big a motor on it, so it flies out in the park out the back of my house now.

Unfortunately I don't have the time to build you one, (have too many of my own things to build ) but could probably put you in touch with someone who can.

What part of the country are you in?

And may i just point out that you will not be able to bend depron, it'll crush or bend without a doubt.

It could be possible to land it on water, but you would need extensive waterproofing and the knowledge that it does not dig bows in, even specialised water born planes do, and it isn't pretty, just search Seawind crash into youtube and you'll see what I mean.

The vapor pictured above will not fly outside, even in complete flat calm winds

[toesupwa]

Wow...

I'd like to take on the challenge too... but alas, I'm also too far away... *sigh*..

Here is a plane that i built back in the mid 80's before the advent of micro RC gear. Its a 2 metre wingspan glider and with standard RC gear came out at at 21oz. The RC gear DOUBLED the weight by the way... It was an experiment in how much weight i could save in a standard balsa construction glider, the original plan was an 'RO8' from an American plan.
I think i could still save probably another couple of ounzes in the construction and probably 2/3rds of the weight of the radio gear. 

A few suggestions on weight saving.

1/ Add holes. By putting holes in things like ribs (how thick are they?) you add air.. Air = weight saving!.
2/ By tissue covering and coloured dope, you are adding weight. Consider some of the iron on lightweight (and pre coloured) covering materials.
3/ Try a smaller battery pack. It may reduce your flying time, but the weight saving could be considerable.

Are the plans available?.. I might be tempted.... 

How big is the ship you will be flying off of?... 

[tonyH]

Evenin' again all!,

There is one fundamental that I need to sort out first.

The battery I've been using is a 2 cell lipo of 300MaH. It's a 20C setup so I understand that maximum draw would be 6 amps/44-45 watts.
 
The prop is 4blade 3.5in diameter and this is limited by the fact that the Walrus is a pusher. This seems to be the biggest limiting factor.

Total wing area is just under 85sq.ins.

What is the likely weight that it could fly at?

I reckon that using the current electrics it could be got down to 4.5 oz or so but is that likely to be light enough and since the aim is to catapult launch it, would it be strong enough?

Hi Andy - I'm in Suffolk

Hi Toesupwa - The ship is approx 14ft long and the launch catapult is approx 15ins - Rough plans off the web only. Semi-scale rather than scale.

Sorry that it's not true boating Martin!

Tony

[Arrow5]

Some examples of bent Depron. (sorry about the dust) It is rolled round the edge of a table or similar with the palm of the hand, gradualy forcing the shape, slight kinking of the inner surface indicates too fast and too much bending at a time . The models are "way-off-scale" Sopwith Pup types and not very sophisticated GWS geared motors. The silver balsa and film monoplane with Cox glo motor was twice the weight of the Depron electric biplanes.  A compromise between scale and a practical look-alike is the best bet.  Latest technology from the suppliers to the indoor fliers adapted, just be aware that infra-red control isnt good for sunlight days, stick to "normal" frequencies.  Toes , a blast from the past !

[Arrow5]

You were posting at same time as I was  Have you tried posting on an aeromodelling site ? Catapult isnt all that important as the flying speed will be low and thrust will be enough to pull it off with no problems.  Here is a cheap infra-red guided toy from Maplins to show the advances in remote control model planes. Look at the size of the servo and the gears, not practical but the non toy guys are your source of such ultra-light gear that is reliable.

[Arrow5]

Tony,  Get the latest edition of the model aircraft publication RCM&E ,Feb.2009 and look at he review of the "Minimum Fly Baby" on pages 107 &108.  It comes with a 2.4gig radio. You could learn a lot about foam construction etc power unit and li-po battery etc for only £70.  How is the build coming along with the ship ?

[tonyH]

Ta Muchly! I'll get the mag. Penelope is still in the drawing office 'cos I need to get the current build finished for the next Mayhem Weekend. My son is determined that we're going to do it anyway and he's trying to persuade his DT teacher that it would be acceptable for his A level project.

Tony

[Arrow5]

Tony, get the teacher to make a manned model , just a bitty bigger and all the educational values of design, construction , navigation, the sea, naval history, the sea,outdoor pursuit (not fooball) and all that. Target date any pre Olympic at Weymouth Model Boat Festival, class outing !

[tonyH]

Not a Chance!!!!!!!

He's toooooo expensive as it is - I keep on trying to get him to focus, but it's still rugby, badminton, golf, archery, cricket, hockey and...women..........and.....

The only way I'd sail it is on an escape cruise, preferably as far away from these shores as poss.

Nice idea though!

Tony