Build Log Thread formally known as Cyril Carr's "Supermarine Walrus," Part II, a bigger one!

[L over D]

Keep up the good work rotorheid, that will be really nice shagbat!

I made a Walrus-design last spring that was a little more basic but very focused on flying/swimming. Cyril Carr´s design seems to be a little bit smaller but with much more scale details. I was also surprised to read that Carr had not flown it from the water and actually doupted that i would work. I hope you dont mind me posting some pics of a Walrus in it´s true element!
The important thing is the "steps" under the fuselage and the floats. If they are to shallow the plane will not let go of the water. But with the steps set right a Walrus is a dream to land a take off from any pond, lake or river.



Happy swimming!

Johan

[rotorheid]

Hi Mr Lift/Drag,
Absolutley delighted that you put your pictures here, a pleasure sir.
Can you please supply more information on your Walrus? Specs and such like, thankyou.
I started installing the motor and radio bits last night, I made a fundamental error with my nacelle, too short, so spent a while resolving that problem. The motor I have is an XTRA 2815/24 good for 80+ watts. Weight with all componants but no paint or detailing is 310grams, it will be heavier than Mr Carr's original, I think my calculations will allow a MAUW of 400grams for a wing load of 5.5 oz/foot squared, still, not a lead lifebelt, I hope. I fitted a 7x?? prop I had spare as it gave me a max continious power of 70Watt, I use a mixer on throttle for an switchable, rated, combat power selection (85Watt)for emergencies. Cheers mates,
regards to all, Al

[rotorheid]

Hi Guys,
Tackled the wing tip floats after running the motor to test prop clearance on wing trailing edges, no mini snow storm, phew!
Pictures say it all, on with the next part, fitting out. Afterwards a final WBPU coat for water line and below, best to let dry overnight before continuing with rigging and paint scheme.
Cheers mates,
regards to all, Al.

[LONGBIKE]

Rotorhead,

This is really a great looking plane. I have got to build one on these where did the plan come from? Im not sure what rcm&e is.

Thanks

[meatbomber]

Longnbike
RCM&E Magazine from the uk, you can order back issues here : http://www.modelflying.co.uk/editori...scribe&sp=&v=8
I got me the one with the Walrus too it`s the february 2008 Issue (No.109), got mine in just 3 days shipped.

Rotorheid:
Your building speed borders to manical !
she`s looking really good, what i don`t quite get is with the landing gear not in a fixed retracted position but in the moveable configuartion that is in the plans, the wing gets it`s stiffness against folding up only from the little ply mounts for the folding wing mechanism ?
Cheers
MB

[rotorheid]

Hi MB,
Yes, I'm afraid I was diagnosed with CMBD some years ago, but I learn to live with it, I get such a rush when I lay the plan out for the first time, or open a new tube of glue, sort of a build junkie. hahaha.

The stifness in the wings on Carr's plan is from the completion of the basic box shape, he has a strong anchor point for both wings, two top and two bottom. There is a "Jury" strut at the leading edge of both wings to keep the form rigid when folding the wings back. The interplane struts hold the wings rigid at the tip end. So when the lock pins are fitted through the ply wood on the wing roots, the whole assembly becomes a rectangluar box when viewed from the front. The rigging wires, landing and flying wires become functional to add to the rigidity. It shows this on the plan but is not obvious, and it works. Same principle as most aircraft with a connection to the upper and lower spars to the mounts on the fuselage.
My Walrus will be the prototype version without the jury struts as I do not have the fold system. Hope this makes sense for you. Cheers mates,
regards to all, Al

[L over D]

[quote=rotorheid]Hi Mr Lift/Drag,
Absolutley delighted that you put your pictures here, a pleasure sir.
Can you please supply more information on your Walrus? Specs and such like, thankyou.

I will try (it was some time ago and I sold/gave away all the 6 pcs that was built). Wingspan was 100cm, the upper wing was only 3mm Depron and the lower was 5mm. My prototype had an ATOW around 280gram I think, small outrunner from Dualsky (forgot the type, around 25-35g) with an 12A esc and 2s 1000mAh LiPo-pack. Wingstruts was also 5mm depron (would have looked soo much better with wood or carbon... ).
The thing with my design was the CG, if set at 1/3 of upper wing it was very sensitive to thrust changes and generally unstable during descent. Since the designs are fairly similar I would recommend to set the CG at least at 1/4 of the upper wing (don't know what Carr recommneds for his plane), it also helps the handling in the water if it's slightly nose heavy.
With the CG right it flew very nice indeed, perfect for a calm summer evening (even though it took "strong" winds and "rough seas" rather well)!

Must agree with meatbomber, you are building like it's going out of style! Keep up the good work, it's very inspiring to follow your thread!

Sea trials and test flying on during this weekend?

Johan

[LONGBIKE]

Thanks MB,

But I guess I'm just stupid because when I go to there site and click on back issues it will just give me the one choice that I dont want and I cant change the issue number.

[meatbomber]

just send them a mail they`ll send you the issue worked for me

[rotorheid]

Hi guys,
Made the access panel with a wide sealing surface, will use Vaseline, Petrolatum or thickish grease to prevent/reduce water ingress. I have no sealing chemicals like corrosion X or experience of them. Got the cabin/canopy built onto the deck, needs finishing off but getting close to the Fun bit. The weather is pants just now so will take time tomorrow to complete and possible "pool trials" and adjusting on Friday. C/G should be achieved with battery position, no ballast.

Cheers mates,
regards to all, Al

[rawy]

Nice Job Rotorheid, really impressed by the building pace, was expecting some more info on that engine dummy, nobody else asked so I do

Except in cases of major crashes I never had problems with water on/in electronics, I try to avoid contact with water by placing receiver and esc's protected by .......yes foam

The advantage of our favourite building material is that it needs power to bring it under water

rawy

[rotorheid]

Originally Posted by rawy

Nice Job Rotorheid, really impressed by the building pace, was expecting some more info on that engine dummy, nobody else asked so I do


rawy

Hi Rawy, Guys,
Glad you asked for some info, when I took close up pics I saw that one of my prop retainer screws was missing, found it under the work bench ! Was due for a tidy up so it could have gone in the skip, thanks.

Full size Pegasus Radial Engine. circa
Type: 9 cylinder spark ignition air-cooled poppet valve radial engine
Cylinders: 9 cylinders in one row
Valve arrangement: 4 valves per cylinder
Bore and Stroke: 5.75 x 7.5 in
Swept volume: 1,753 cu in (28.7 litre)
Compression ratio: 5:1
Max revolution: 2,600 - one minute
HP range: 600 - 1010

I worked briefly on it's big brother, the Hercules, a two row, 14 cylinder,
37 litre monster when I was a young apprentice in the RAF (a long time ago!)
Model size Balsa Pegasus.
I made a cock up in the distance measurement for my prop position, as mentioned in post #17, I laminated some light balsa sheet, sanded to a circle and glued 9 pieces of balsa rod around the side. I wound some thick wool on the rod and stuck a small balsa stick for the push rod covers. I smeared some PVA glue with the fingers over the wool to bulk it out, sanded and painted when dry.
Hope this helps, off to the work table again, cheers mates.
regards to all, Al

[rotorheid]

Hi Guys,

Took forever to put in 4 pieces of kite string for the control hook up, next time I do one of those setups I will get them in before I close up the fuselage, what a faff! No matter, servos fitted and working, rudder and water rudder made, looks tiny hope she is stearable. Flying and landing wires done, with thinner kite string. "What's that Bob?, your kite seems too near, and turns to the right all the time...eh... can't think why mate."
Base coat of aluminium applied, bloody can ran out too soon, so it's thin in places. Pictures tell a thousand words so here are some more. Cheers mates.
regards to all, Al

[meatbomber]

sooooo nice !!! what paint are you using ? most spray paints i find are eating the depron and the "styro safe" stuff i have not seen a silver yet...

[rotorheid]

Hi MB,
Thanks mate, I just have to get my magnifying glass to read the info on the can.
Looks like it's Dutch/Nederlande/Holland as the first language on the can is Dutch.
Bar code and stock no. 5 412966 159336 Pearl Silver.
5 412966 168109 STC Silver 810

I got it from local craft shop, some of the cans were u/s with the heat and old stock, hope they still make it. BTW if you put two coats of WBPU on the depron, and spray car acrylic gently from a bigger distance than normal it doesn't eat the foam too much, I did disolve a foamy jet once in the early learning process Doh!
regards Al

OK found the place, Belgium, check this link out.
http://www.ghiant.com/our-brands/art.../hobby-colours