Ideas for a HUGE foam core airplane anyone?

[kansascloud]

I saw the video on Youtube of the 24 foot span Pink Floyd and was inspired! :D I want to build something like it but probably not quite that big, but super large. I've been modeling for over 30 years but have never had anything really large.

I want to build something out of foam, 3 channel, very simple and easy to fly. I have 400 acres available to fly off of, so the chances of harming someone other than myself is slim. Don't thing will be AMA legal by any means.

How big of an airplane can I power with an off the shelf brushless outrunner?

I'll probably start hacking foam next week? Just wanted some sort of guidline on how big and heavy I can go before it gets totally crazy. I don't want to get into multiple motors with gear boxes and things like that. Going with the KISS concept.

Thanks for any suggestions!

[kansascloud]

I'd like to keep the cost of the motor system and batteries under $1000. Is this a reasonable budget?

[eye4wings]

Hi Kansas!
Sounds like a case of cutting your suit according to your cloth.
Which is more important? Keeping to budget or sheer size?
Either way have you looked at a scale XB-15?
Huge wing area which using foam should give you a model with a ridiculously small wing loading - probably in the region of 8 -10 ounces per square foot.
Four motors with the biggest (scale sized?) props they will swing would be efficient in transferring the power to the air. Bigger props mean less batteries to carry, therefore lighter on both wings and pocket. Fixed undercarriage would not look unduly out of order on a type of this enormity and she'd fly on combined aileron/rudder, elevator and throttle. Possibly around 200" span?
Looks doable to me!
Only you'd definitely need to 'keep your eye on the wind'!

That's the way I would go.
The trouble with going single motor is that bigger motors get much more expensive need bigger cell counts and so on. I'd rather have a bit more complexity and stay cheap and efficient.
Of course if your looking at just another Cub... (yawn) its been done so many times...

[kstrach]

Hey Kansas,

Having helped Flybike with his Pink Floyd build, I thought I'd offer a few suggestions. If you just want something big that floats around and is super simple to build, I'd scale down the Pink Floyd to a 12' wingspan or so. Flybike and I have built one at this size, and it flys just like its bigger brother.

If built light, a 12' Floyd should weigh in at around 12-14 lbs AUW, depending on your power system. Unless you are flying in almost no wind, I'd highly recommend at least 1500 to 2000 watts. This may seem like a ton of power in such a light aircraft, but with nearly 22 square feet of wing, you'll be glad to have it when you need to fight your way through a headwind. With a cheap power system from HobbyKing, you could probably even go bigger than 12', but personally, I'd rather have more power in a smaller airframe. The extra power will also help if you ever want to carry a payload. We had no problems carrying ~ 10 lbs worth of equipment with an AXI 5360 and dual 27" propellers :D If you'd like more details, let me know.

Good luck with your project

- Kris

[foamnpacktape]

Are those Moths in your avitar? eyes not so good, monitor neither.

Pink Floyd was cool, but a simple giant moth, that I'd like to see, also functional rigging can help keep the weight down and stiffen giant floppy wings. Nothing floats like a biplane. Drag may be an issue though, and you don't get the significant span of a monoplane.

What do ya think?

foam.

[kansascloud]

Kris:

I'm taking all your suggestions to heart. I think about a 12 foot Pink Floyd is about where I want to go. 12 feet is enormous in my book. Yes, I would rather have excess power than just a huge airframe. I know nothing about the power and radio setup on a large electric. I've build a 1/3 scale Zenoa powered airplane years ago, but that was a whole different deal. I assume you have a completely seperate power system for the motor?

I'll probably just engineer my pink airplane as I go. I've build several scratch built models that way and they all seemed to work out pretty well. I am confused about your comment on DUAL 27" propellers? Isn't it a single motor?
I sure appreciate your help.

[kstrach]

I am confused about your comment on DUAL 27" propellers? Isn't it a single motor?

Yup, single motor, but with two 27" propellers bolted to it to make a 4 blade prop. We used two 5s packs in series to power the motor, and a separate battery to power the receiver and servos.

Pink Floyd was cool, but a simple giant moth, that I'd like to see

Funny that you mentioned this. Flybike and I seriously considered building a full scale Pitts Biplane out of pink foam at one time. Maybe some day :)


- Kris

[Airboatflyingshp]

You could do a Cri Cri 1:1 Rc or a few other vintage Microlights, Woody or better a Dart Pup. or a Dornier Skyservant one motor two dummy engine pods belt driving two props either side of the nose.

Stick a gearbox on an outrunner and you can go big!! http://www.flyelectric.ukgateway.net/hurri.htm go to the site map and look http://www.flyelectric.ukgateway.net/largesum.htm

links in here to twin boomers
http://www.rcgroups.com/forums/showthread.php?postid=11937448#post11937448

another great subject is the Anderson greenwood light plane a vintage pusher... I have a smaller plan for one the short skyvan is another easy giant foamy build using lagely foam.

[Airboatflyingshp]

Check out the UK LMA site for ideas....foam ribs infills and formers skinned in balsa, tubular wing spars and keel cores, look at the spruce goose trad built but used Nimhs and S600 geared motors, blue foam covered in brown paper and you can build giant PSS models that can be electrified http://www.pssaonline.co.uk/ giant Vulcan's using a folding pusher prop in the tail cone sound appealing? Don't confine yourself to the usual subjects either.

A personal favourite and proven flyer is the M55 mystic again could be done as a pusher but the same company do some funky twin transports under their civil /millitary design brief.

If you want links go down to waterplanes and look through the sticky ;)

[foamnpacktape]

Funny that you mentioned this. Flybike and I seriously considered building a full scale Pitts Biplane out of pink foam at one time. Maybe some day :)
- Kris

Cool, I don't have the space, or budget to even consider such a thing, but like you said "maybe someday" :)

Regards,
foam.

[Airboatflyingshp]

If you want to think about a biplane try a Sorrel Hyperbipe they fly beautifully and they are very easy shape to copy...they are also vey distinctive :D

[kansascloud]

I think I will start to hack on some pink foam as soon as I finish up my Tiger Moth 400? I have something simular to Pink Floyd in my mind. I think I will limit it to a 12 foot span or so. It will definently have the big thing going for it at that size, but the whole thing should be a little bit more managable at that size. Once the airframe is completed I will post photos and specs and ask you guys for help on selecting a power system for it.

[Hepdog]

Well 12' really isn't all that big. I mean it's big but you don't really need 1000+ watts. I think it's all about the efficiency of the design.

My B2 is a 10' wingspan and weighs in at 8lbs. Powered by 2 tiny Grayson Super Mega Jets spinning APC 6X4's. Each motor only draws about 32 amps at WOT on 3s - thats under 700 watts total. I only need WOT for take-off, once airborne it cruises around quite fine at about 1/2 throttle.

Remember that multi small motors and props offer more disc area and hence more relative thrust than a single big prop. If you want 12+ foot wingspan consider building a twin of some sort. The cost of 2 60 ampish ESC's is pretty comparable to one 120 amp (not to mention lipos etc)

[awrightbrother]

I had designed a scale 60" B26 Marauder a few months ago. A club member wanted me to scale it up to 160" span. I just finished cutting the foam for him and he has started the build. I hope to be able to start a thread as soon as I can get some pics from him.

Before he picked up the kit, I did take some pictures of the kit. To get some idea on how it may look when finished, you may want to look at the 60" version on my website http://www.wowplanes.com/product_info.php?cPath=49&products_id=116

Don't forget to click on the Flight Video link to see how it flies.

There is also a build thread where I and a couple of others built ours at http://www.rcgroups.com/forums/showthread.php?t=940102&page=2

[Airboatflyingshp]

That is big, bigger possibly than a CriCri!

As Hepdog said "Remember that multi small motors and props offer more disc area and hence more relative thrust than a single big prop. If you want 12+ foot wingspan consider building a twin of some sort. The cost of 2 60 ampish ESC's is pretty comparable to one 120 amp (not to mention lipos etc)" ..........even cheap geared brushed motors on a single or pair of controllers can work well look at the UK LMA site and the fly electric gallery and Ivan pettigrews work. Northrop flying wing or how about

the ABFS SPAD challenge links section to all,

Westland wing http://www.rcgroups.com/forums/showthread.php?t=686114&highlight=Westland+flyingboat Hepdog this could be right up your street ;)

Do212 http://www.rcgroups.com/forums/showthread.php?t=1013151&highlight=Do212

A Boeing Duck http://www.rcgroups.com/forums/show...=7#post11769569

Name your fancy and we will no doubt be able to dredge up the info on whatever.

[hawaiianspork226]

balsa products has some VERY large outrunner motors for VERY cheap.

i got their largest- about 8 horsepower- 6500watts- to turn a 30x12 prop. very, very powerful, but you can fly a HUGE plane with it. im using 10s (2 5s packs) zippy batteries, and a castle creations HV 110 esc. the speed control is the really pricey part... even then, it doesnt really outweigh the rest of the system.

bp motor- about $215
batteries, shipped - about $249
ESC- dont remember, i think it was around $300?

so for about $800, you have a motor system equivelent to about 85cc gas engine... on a floater, that is a HUGE plane, potentially.

to put it in perspective... a high-end, name brand motor (the ones im thinking of are purple and rhyme with smacker) youre looking at 900 to 1100 dollars. for JUST the motor. i cant justify that... im not sponsored, and not competing. just trying to have fun :)

i hope you make something HUGE, i wanna see

-david

[hawaiianspork226]

OH hextronic also makes gigantic motors for cheap.

another thing about big motors; or rather, the big one i got- try and get a motor with a "normal" propellor /mount/adapter. i had fun trying to make a drill guide for mine; its a 6 hole bolt pattern; its the only one id ever seen like that, but i didnt think of the rammifications before i ordered it.

-david

[Airboatflyingshp]

Build big, build light use a a geared/pully drive -follow the vintage/motor glider microlight principles let the wing generate lift and work with what you've got. Substitute time, imagination and lateral thinking for big bucks and go faster gratification. You might not get a 3d flyer or a conventional warbird but you want to build a big plane on a small budget...... work with what youve got and dont be affraid to experiment. Look up InterX
chec out the mec site for their slant on it.

[N99JH]

balsa products has some VERY large outrunner motors for VERY cheap.

i got their largest- about 8 horsepower- 6500watts- to turn a 30x12 prop. very, very powerful, but you can fly a HUGE plane with it. im using 10s (2 5s packs) zippy batteries, and a castle creations HV 110 esc. the speed control is the really pricey part... even then, it doesnt really outweigh the rest of the system.

bp motor- about $215
batteries, shipped - about $249
ESC- dont remember, i think it was around $300?

so for about $800, you have a motor system equivelent to about 85cc gas engine... on a floater, that is a HUGE plane, potentially.

to put it in perspective... a high-end, name brand motor (the ones im thinking of are purple and rhyme with smacker) youre looking at 900 to 1100 dollars. for JUST the motor. i cant justify that... im not sponsored, and not competing. just trying to have fun :)

i hope you make something HUGE, i wanna see

-david

Are you talking about this motor?
BP R7050-6 Brushless Outrunner Motor
How much experience do you have with it? What prop and what rpm are you seeing, please?
I am interested in buying one.

[eye4wings]

8 hp?! I'm guessing you could fly a CriCri on two of those!
But only 30x12 prop surprises me - I used a 20 x 8 3-blade on a Vortex 53 series and four cells. Mind you the Revs per volt is very low on the Vortex.

Still I very much like the price. Do they do smaller motors, like 1HP (ish)? I must find their site...

(unlike Castle Creations prices!)

[Airboatflyingshp]

There is a Cri Cri flying out there with two model gas turbine engines on it in place of the usual ICE motors and props. The guy I belive is German. Ive seen the video.

[Neogenesis]

I would go with this combo...

HXT 80-85-B 170Kv Brushless Outrunner (eq: 70-40) $99.96
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=5141&Product_Name=HXT_80-85-B_170Kv_Brushless_Outrunner_(eq:_70-40)

TURNIGY Sentilon100A HV 5-12S BESC (Ver4) $109.99
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=4691&Product_Name=TURNIGY_Sentilon100A_HV_5-12S_BESC_(Ver4)

Some recommend changing the bearings out on the motor before you even start, but it's still a heck of a lot cheaper out there with a bearing change for the power it makes.

Neo

[frednjess]

This one was just big enough to piss off my wife...wonder what she'll do when I make the 16' version?
This flying wing is 8' WS, 2400 square inches, 6 oz./foot^2, and flies on about 200 watts. It's no screamer, but it does fly.
http://www.rcgroups.com/forums/showthread.php?t=998356
Sounds like a cool project.