Well, after tryin the SPAD thing for a while I decided that foam might be a better way to go. Don't get me wrong the durability of a spad is unmatched but the weight of the damn things just won't go down. Everyone I built was just to heavy. Anyways here what I'm gonna do. I got me a sheet of 2" builders foam "extruded polysomthin" I wanna take a handsaw and rough out the shape of the wing and fuse. Sanding block it from there to get my airfoil. Permanately glue it all together and be flyin in about 10 hrs work. I wanna go kinda with the spad philosophy. Cheap/ quick/ ugly/

The fuse will be the same 2" stuff stood up like a profile with the wing cut out.
The tail feathers will be 3/4" foam.
Balsa and ply pieces glued in for hinges, landing gear etc.
Polyurethane for fuel proofing, (I don't wanna cover this with glass or film)
OS 32 for an engine
Airtronics gear (full size, no micros)

Goals for this plane/
Slow landings
Fair vertical power
No need to hover
Stable in light winds
Somewhat aerobatic
Good inverted capabilities (I wanna practice that)
Hoping for 4 to 4 1/2 .lbs

The only thought I have so far.
48" X 14" wing with 2" ailerons giving me a 48x16 inch wing = 768 sq in.
fully symetrical/ no dihedral

Any thoughts on fuse length and tail surfaces?
Any thoughts or ideas on any of it?

Look up Crazy Herb's threads on cheapo Big Pink Creations.

Just a hint. Try using the water based polyurethane to soften and adhere newsprint patches where you want local reinforcing. A layer or three of newsprint over foam really strengthens it up against local vibration. I did a couple of control line combat models years ago using thinned carpenter's glue and newsprint over beaded white EPS and could not believe how strong it was. The water based polyurethane would make it a lot lighter and less messy I suspect. And the paper comes to your door for free....

Looks like rain today so I hope this afternoon I'll get started.
Do ya think the wing size (48" X 16") is okay to build around?
The OS 32 is the engine I wanna use and I'm slightly afraid It'll end up being a dog if I can't keep the weight down to that 4 1/2 .lb goal.

If I'm doin the math right (referring to the How to's of scratch building thread)
With a 16X48 wing 768 sq. in.
My stab should be 109 sq in
elevator should be 60 sq
fin should be 40 sq
rudder should be 22 sq

I don't understand
aspect ratio
MAC
tail moment arm
nose moment arm

But I'm learnin.

How about the Shock Flyers
from Hobby Lobby???
It needs electric power!
Check it out!
H

The tail size is much too small for what is obviously a 3D fun fly type model. The wing at 48x16 has an aspect ratio of 3. The MAC is Mean Aerodynamic Chord which, for the most part, is the average chord on a tapered wing or the root chord on a rectangular wing. Technically it's the Span/ MAC or you can also do it by Span squared/ Wing Area. Tail moment arm is the distance between the 25% chord points from the wing's MAC location to the tail's MAC location. Nose moment is the distance from the wing's 25% MAC chord to the prop driver location.

Dude...you need to build a Pink Pattern...

I'm just finishing up this one.... 4.5 lbs with Mecoa .46.

Should be able to CRANK on it....

http://home.comcast.net/~crazyherb-rc/

Good Luck!
E-mail or reply if you have any questions....

I agree with BMatthews...need to go above and beyond the "normal" specs for an aerobatic/3D plane...

CrazyHerb

After finishing the final shaping of the wing I figured out I'm not gonna hit the 4 1/2 .lb mark.
I'm at 1.08 .lbs now. (just the wing)
Thinkin about cuttin it back to a 42" X 12" wing.
My airfoil looks a bit goofy with the "spar" (so to speak) only 2 1/2" back from the leading edge on a 14" wing.
I'll post some pics tomarrow night of the progress.

By the way BMatthews
My computer didn't even know how to qoute your post no# 6 I gotta do a search on "aspect ratio"
Let me finish the wing and show ya what I have and then I'd like to ask ya.
What would you suggest for vert and horiz, tail areas?
I don't mind the idea of going outside the "normal" specs but to be honest I don't fly good enough for somethin wild yet.

Crazyherb,
I like that plane!
I gotta finish this line of thought I've got goin then I think I'll have to tackle that one.
And yes I will be asking "YOU" alot of questions.
I think I can make this plane work it's just gonna need "tweeking" as I go

By the way.
I'll probably have to edit some part of this post cause it also took a six pack just to sand the wing out...

Elarging the horzontal total area to something about 20 to 25% of the wing area will ensure you DON'T have a wild model. The small stab will cause that, not a larger one. The vertical area should be about 12 to 15% of the wing. The hinge lines for the surfaces can be whereever you think you want them. Lots of movable area for that 3D model and only a little bit if you're after a sedate trainer like model.

Here's my attempt at a foam model. I call it the Mac-pie2. Span 36 inches and length 19 inches. Wing loading apprx. 16 ozs per sq/ft. which is light.

A sheet of polystyrene merely shaped with a detail sander. The fins are foam board and the cowl cover is made from a soda pop bottle and painted. With an OS .35 on board she weighs 2lbs 3 ozs.

The styrene is covered in brown parcel paper with 50% thinned pva wood glue and allowed to dry for 24 hours. Next a light coat of glass fibre resin is applied with a piece of 1/64th ply . Weight gain is very small but the model is now very strong.

It could also be converted to electric.


Currently I'm scratch building my own design based on the Mosquito called the Macs-quito. Again foam covered in paper with a 38 inch wingspan and 2 x 400 electric motors with 8 cells.

Neat lookin wing Macx! I can't tell from the pics what ya used to bolt the engine down?

After dreaming about this last night,,, (okay, okay, I dreamed about Shania Twain also) I decided that cutting the wing down to save weight might not be the thing to do. Losing sq. inches doesn't sound like the way to go.

I think tonight I'm gonna rough out all the parts, stack it all up on my scale and just see about where I'll end up.

I just did some figuring.
Even if I end up at 5 .lbs that should put me at 14.97 oz. per sq. ft. I can live with that

Let me know when the test crash...I mean flight will be. Ought to be interesting.

yeah I'm gonna take it up and chase your ultra stick around

Make a 1/8th tray as shown and epoxy inset into the fuz. front. Under the front end epoxy fit hardwood blocks which the engine will bolt into. My blocks totalled 7/16th in thickness. Install to allow for a few degrees of sidethrust. Then cutout front of tray to accommodate engine. I used self tapping screws with Theadlock. Fuel proof the tray. The tray top is velcroed using epoxy. Likewise the tank and flight battery bases are volcroed and the pop bottle top cover holds everything firmly in place.

The last image is my current project a 38 inch span Macs-quito.

That might worry me if i had not seen you fly before.

Sorry it took me couple days to get the pics up but life gets in the way occasionally.

It's comin out pretty neat but I think I'll never hit the weight I wanted.
I think it'll still fly nice enough though.
I'm kinda guessin it'll be a easy flyin plane with some aerobatic ability in a limited way.
(which by the way is probably ok with me)
I got the balsa glued into the trailing edges I just gotta decide wether to use solid balsa or foam for the control surfaces.
I think I'm gonna cover it with newspaper and thinned wood glue. I think structurally it's strong enough it's just that every time ya grab it a little to hard the stuff dents. Plus I spose it'll make it look better with a little color. (I'm gonna find some COLOR funny pages.)

Looks like it's gonna be a winner!

Just personal opinion...I think you could take almost an inch off the top of that fin (or more) and it would give it a little more streamlined look.
It will also help with tail heavy situation too...if you happen to have that arise...

My fins heights are usually around 3/4 to 2/3 of half the horz stab.

Taller rudders have a way of inducing roll and pitch coupling in knife edge too..(kinda acts like an aileron or elevator in knife edge)....so the less rudder you have away from your aircraft centerline the better you'll be.

Ailerons - I usually just cut them from the foam...trim down the top and bottom at the leading edge of the aileron to accomidate sheeting, so the leading edge of the aileron ends up the same thickness as the trailing edge of the wing (where I cut the aileron out) (airfoiled surface) then top-hinge them with packing tape/covering.
I use the thickness of the sheeting to act as a guide to do my cut at the leading edge (leaving the trailing edge the same thickness) then just flipping it over and doing it on the other side:
http://www.crazyherb.com/PLANK/IMG_1250.JPG


Here's a pic of the results:
http://www.crazyherb.com/PLANK/IMG_1264.jpg

I have not had a hinge failure yet.....even on the big ones...

Good Luck!
CrazyHerb

What are ya using to fuel proof that plane?

Clear packing tape....ah-la Zagi method...

I've also used monokote right over the foam...sticks well..just don't let the iron sit in one place too long...

ULINE brand packing tape works like mad....and they sell it in colors.

I've actually flown them with NO covering....as long as you wipe off the goop right after flying....the extruded foam doesn't absorb much....I've flown a little greasy mostly uncovered 1/2A for two years...with just packing tape on the leading edge and down the centerline...

I've just drawn up how I do my sheeting for ailerons and stuff...(airfoiled surfaces)...here:
http://www.crazyherb.com/PlansandDrawings/SHEETING.jpg

Hopefully that explains it pretty well...

Good Luck!
CrazyHerb

Just us a brushless motor with a li-po battery, and keep your weight around 1 pound MAX!!!! the design looks good by the way, nice shaping.

Electrics will rule!!!

theHarpmanDan

I didn't get anywhere on it last night I was doing test pieces of newspaper and glue. I'll get back at it workin on the plane tonight I hope.
Anyone know the best glue / water ratio for applying newsprint? Is it the same ratio for the second coat?

Well it's taken me awhile to get back to this thread with the results.
After 2 crashes due to a bad battery pack, (fixed now) and a few modifications, the plane is a nice flying machine.
I had landing gear on it but 1st night out a weed landing removed them and the loss of nose weight made the plane fly great.
After the rebuilds and just minor changes I came in at 4 .lbs 11 .oz
I let a couple of guys fly it after it was done and they all said it flew good. A little tame for their tastes but a nice flyer.
Ya with the .32 on it it doesn't hover or nothin, and you won't go out of site vertically but I'd say I hit my above stated goals as far as flying goes.
As for build time it took longer than hoped but with some redesigning I think that can be resolved.

By the way.
I call it the "dumpster diver"