leroifort

one week ago I dreamed that I stored for the winter my marutaka p38 near my sig wonder and that a baby was born. What a ugly beast !!!
But at this time here is how my kitchen table look like
you can see
2 wonder kit
1 large millimetric paper (don't laugh with what i plan to do it will be faster than autocad)
1 box of cigaret
1 cup of cofee
I am ready for a long night (it's night here)

all my curent project are stoped until i will have completed that one (i have an ultra sport 1000 nearly completed, but.......)

my first interogations are
-should i keep the central wing section section to his minimum size (prop clearance) or make it bigger to increase the wing aera ????

for take off i have tree options

- a prehension device on the middle of the wing's intrados between the two fuselage and hand launch
- a fixed gear
- a mobile undercariage wich stay on ground once airborn

what about a central flap/speedbrake ?

I wait your opinions

Unstable

real cool.

keep us posted.

leroifort

ok, here are the results of my first brainstorming
power plant 2* magnum .15 pro
wingspan 122cm=48 inch
estimated dry weight 1600 grams
estimated wing load 57 Gr/square Dm

that's for a gearless version

because i am not a specialist in hand launched birds, I ask myself if the wing load is not a little bit too hig ????

leroifort

ok, for the servos

all HS85 BB for flights controls

2 for ailerons
2 for elevators (split elevator)
1 for central flaps speed brake

and two for throttles

Baldeagle

My Feedback: (7)

I have bad dreams too. Like taking a Bride Big Bee and putting 4 motors on it. I just hope its normal.

leroifort

i forgot the idea of the central flaps

leroifort

I am at work now, a litlle bit tired. But I am making the list of the wood I need, not a lot, just wing spars and central wing section sheeting. I'll start bulding the wing tonight.

leroifort

Ok I have all my wing ribs, there are 4 diferent kind

1) the standards one (all the wonder ribs are the same)
2) the standards one with hole for wiring
3) standards with holes and enlarged spare notches for the central section (spars are double in the central section)
4) the model 3 made in 1/4 balsa to give a suport were the two leading edge sheeting sheets will join

leroifort

two hours later
all the ribs are gluied to the lower wing spar (except the 1/4 balsa central) and the ailerons servo trays are in place.

After seeing the joined pic I had nearly a eart attack, my table look warped on the pic, but I confirm, it's flat !!!

Johng

My Feedback: (4)

Longer wing, same spars => more stress. Slap some carbon fiber strip onto those spars to keep 'em in one piece.

John

leroifort

thanks for your suggestion


both bottom and upper spars are doubled in the all central section till the first rib of each outer wing panels, and I also plan to install shear webs all along (no shear webs on the original), isn't that enough you think ?????

I forgot to mention also that on the center of the wing I plan to instal a plywood brace betwwen the two first ribs (that's why my central rib isn't in place yet, it will be in two parts

Johng

My Feedback: (4)

Ah, yes - I didn't see that comment about double spars before. You've got it handled, I'm sure.

leroifort

I try to handle, I try, but till now it look reliable. I should go trough the wing building without any problem and suspicion of structural weakness
I am more concerned about the firewalls building, the right thrust ,the oportunity of the reversing of one engine and so on.


the facts are that the wonder has no rudder, only two big fins. In my design the two fins are located in the line of each engine not very far away from them(just behind the wings) , this let me supose that in addition to the the torque of the engine, there will be also a a parasite yaw induced by the spining propeller airflow (dificult to tell in english what I am thinking about)

go against all that without rudder will be complicate I think

On that part of the design, I'll cerainly pick my inspiration in what i will read on this thread and the valuables coments of members like johng, twinman and the others

leroifort

just received an email from a member suggesting me to put a gyro to control the yaw axis, nice suggestion, but how to control the yaw axis without rudder ??????,

leroifort

tonight, I added the top star, central plywood brace(2mm), central front 1/4 balsa rib, leading edges, trailing edges and the upper trailing edge sheeting.
I report to tomorrow the boring job of making the shear webing ( don't really know why, but i have always ate making shear webs)

leroifort

decisions i must take now

Tonight I plan to start the fuselages, making the fuselages sides mean that you know what amount of right thrust you are going to give, so i must take decisions now about the reversion of one engine and the firewall positions

Need your opinions folks

leroifort

I changed the power plant in two OS.15LA, because that's what my LHS have actualy in stock

MinnFlyer

My Feedback: (4)

I see lots of interesting possibilities here!

leroifort

my design looks like th bottom one of your pics, but without the central fuse (no place enoug, I kept the distance between engines minimal, based on 10 inch prop with one inch clearance)

I am not very worry about the one engine out perfos , i just need to be able to bring the plane back above the field for deadstick

I am more concerned to have a aircraft flying straight without rudder on two engines at take off power and at the relative low speed of a hand launch.

leroifort

the 22 shear webs instaled and uper leading edge sheetings, wings will be resting weighted for 24 hrs

leroifort

my wife "forgot " to go to the hobby shop collect the engines, so i'll go monday to collect them myself
I'll start the fuselages when i'll have them

I plan those settings in the firewall mounting

3 ° downthrust both

right 3° right thrust
left 0°

I plan also to shorten the original front fuselages by a good half inch (will depend of the lenght of the exhaust provided with the .15LA because the exhaust has to clear the wing

Johng

My Feedback: (4)

Hmm - why not add rudders? It is a twin after all.

I added rudders to my single. Thing would do a flat spin like a frisbee and high speed snaps were instantaneous.

you may want to make the fins taller than normal as well - to get more effectiveness. The bigger wingspan will need more effective verticals.

leroifort

why not add rudders? It is a twin after all. µ

that's an excelent question !!!!

I don't know why I reject this idea since the begining of this story.
Maybe, it's because I want to keep the thing light and simple .
I have to admit that a micro servo, some pushrods and hinges are not going to raise dramaticaly the wingload.
My first idea of a central speed brake flaps had increased the weight also, if I have to increase the weight, it's more judicious to put rudders than a central flaps, especially on a twin.

So, OK let's go with rudder, but i'll make a concession with the voice crying in me, rudder on the left side only.
My great planes tomcat flown extremily well with one rudder

I already planed to enlarge the fins, the same ratio I enlarged the wing

Johng

My Feedback: (4)

I just mounted a micro servo on the centerline, thru the deck with the top out in the breeze. I ran 2-56 pushrods in a "V" to each rudder, just out in the open. Didn't make much diffeence in performance with an OS 25 up front

Johng

My Feedback: (4)

BTW - my own thoughts for Wonder bashing would include making a Giant scale one, with gas motor and retract landing gear. If you look at a Stinger kit, that would be a good kit to bash into a GS Wonder.