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FTCC'18 Ohka Model 43(x) -- Team Motherless Child

SlingShot

Maneuvering With Purpose
#1
Team Motherless Child is proud to announce their intention to develop and disseminate the Ohka Model 43(x*)

Here is a drawing of the Model 43 K-1, 2-seater trainer variant which is essentially identical except for the forward trainee cockpit:

Ohka_43_K-1_Kai_3D_view.GIF


Which is also more or less the same s the Model 43B:

ohka 43b.jpg

Team Motherless Child is actively recruiting investors and know-how.

* theoretical fighter variant equipped with extra fuel and the "nose of destiny" which includes (3) 12.7mm machine guns and (3) 20mm cannons.
 

SlingShot

Maneuvering With Purpose
#3
News Release

Team Motherless Child is happy to announce that DamoRC has stepped up to submit a bid for the Ohka design. We have also solicited bids from other designers as well. A bomber/launch aircraft is still required. A plan to modify a captured B-25 is also being considered.

The team has seed money and is looking for a workspace.
 

DamoRC

Well-known member
Mentor
#4
Thanks for inviting me to the team Slingshot!

First effort at plans should be posted this weekend using the same minimalist design approach that I used for the Reichenberg.

DamoRC
 
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DamoRC

Well-known member
Mentor
#5
Okay - first draft.

This is the Sketchup model overlaid on the threeview

10 - First attempt with threeview.jpg

And this is what the model looks like.

11 - first attempt complete.jpg

Agreed with Slingshot on a 1/10 scale, built around a 70mm EDF, simple flat bottomed wing. Unfortunately at 1/10, the 70mm EDF is really, really tight. So I scaled it up 10% from there to make sure the EDF would fit. Also, Slingshot recommended some cheater vents for the EDF and looking at the size of the ducts on this model, its going to need them so as not to starve the EDF.

Will unfold the parts and put together rough PDF plans tonight / tomorrow.

DamoRC
 

SlingShot

Maneuvering With Purpose
#6
Awesome! And we're off and running. You can just look at that thing and know it's gonna fly great.

We still need pilots and fabricators. I do believe that I will proceed with a prop version first. Those things will zoom right on off of the catapult launcher.
 

SlingShot

Maneuvering With Purpose
#8
Press Release

Press Release

Team Motherless Child is happy to announce that in addition to a negotiated airframe technology transfer, it has also experienced a technological breakthrough in the area of jet engine (EDF) performance.

Looking for adventure? Excitement? A one-way trip into naval history? TMC wants you!

* Bomber Designer
* Test Builders
* Test Pilots
* Exhibition Pilots
* "Temporary" Pilots

First round of draft plans attached. Tiled PDF, Sketchup model, DXF, and DoubleCAD (2CD) files in the attached. These are rough (no labels or color coding). Let me know if there are any questions.

Note: scale is 1/9 to accommodate 70mm EDF
View attachment 92632

EDIT
Rev 2 of draft plans attached. Scale 1/10

View attachment 92714

DamoRC
 
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Userofmuchtape&glue

Posted a thousand or more times
#9
Hey Chaps,

I'm in AU so I can't get to FF but I would love to help if I can!

I don't have foam board, but I do have 5mm HK XPS that I can coat in tape for folds.

I also can't really help with plans ATM as I am still learning TurboCAD but I can crash-ah, sorry test them for you!

Abe
 

SlingShot

Maneuvering With Purpose
#10
Hey Chaps,

I'm in AU so I can't get to FF but I would love to help if I can!

I don't have foam board, but I do have 5mm HK XPS that I can coat in tape for folds.

I also can't really help with plans ATM as I am still learning TurboCAD but I can crash-ah, sorry test them for you!

Abe
Alright! Howya doin´ Abe? Glad to have you. So building and test flying. Super!

This shop is slow to get going. Mostly on me. The chief designer has been the only one working hard until now.

Look for a PM for a heads-up on the development program.
 

Michael763

Well-known member
#12
Looks like you are making great strides. I like that you included the SketchUp file in your plan zip. I will do the same with mine, it shares more with the community.
 
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DamoRC

Well-known member
Mentor
#13
@SlingShot and @UserOfMuchTape&Glue

I would hold off on building the plane based on the Rev 2 plans or at least be aware of the following issues discovered during the build of this rough (very rough) prototype:

1  - First Build.JPG

(1) - There is no real clearance for down elevator. Even if you use the double layers of foam for the horizontal stabilizer (which I didn't do on this model) with the full piece on top there will be very little down elevator clearance. You can simply hack some of the rear fuse away to make some room if you like. You will also need to cut a little more clearance into the vertical stabilizers

(2) In the PDF, the order of two of the fuse pieces is mixed. The first printed straight (not tapered section) goes towards the tail, and the second printed, longer straight section (with the wing cut outs) goes towards the nose. Believe it or not, I assembled the fuse to completion with these pieces swapped and then couldn't understand why the wing was so far back in the fuse, almost at the tail :confused: Had to cut her up and re-assemble!

Beyond that she went together okay. The rounded fuse approach is a little trickier on this diameter fuse (it seemed easier when I was putting the Reichenberg together).

DamoRC
 

SlingShot

Maneuvering With Purpose
#14
@SlingShot and @UserOfMuchTape&Glue

I would hold off on building the plane based on the Rev 2 plans or at least be aware of the following issues discovered during the build of this rough (very rough) prototype:


(1) - There is no real clearance for down elevator. Even if you use the double layers of foam for the horizontal stabilizer (which I didn't do on this model) with the full piece on top there will be very little down elevator clearance. You can simply hack some of the rear fuse away to make some room if you like. You will also need to cut a little more clearance into the vertical stabilizers

(2) In the PDF, the order of two of the fuse pieces is mixed. The first printed straight (not tapered section) goes towards the tail, and the second printed, longer straight section (with the wing cut outs) goes towards the nose. Believe it or not, I assembled the fuse to completion with these pieces swapped and then couldn't understand why the wing was so far back in the fuse, almost at the tail :confused: Had to cut her up and re-assemble!

Beyond that she went together okay. The rounded fuse approach is a little trickier on this diameter fuse (it seemed easier when I was putting the Reichenberg together).

DamoRC
That looks pretty good! The thing about the vertical stabilizers, the rough drawing has them inset. The correct setup is like in the two-seater. They go right on the end of the horizontal stabilizer in the style of the B-25.
 

DamoRC

Well-known member
Mentor
#16
Wow - that looks fantastic.
Thanks! The build itself is a little rough but it looks like it might fly.

@SlingShot - understood on the VS. I will move them to the outside. This will also make building easier. I also need to update the plans for the wing. It folded up okay and fit the fuse well but it needs some work. I might go ahead and hack some servos and a pusher into this one just to see how she does.

DamoRC
 

SlingShot

Maneuvering With Purpose
#17
Thanks! The build itself is a little rough but it looks like it might fly.

@SlingShot - understood on the VS. I will move them to the outside. This will also make building easier. I also need to update the plans for the wing. It folded up okay and fit the fuse well but it needs some work. I might go ahead and hack some servos and a pusher into this one just to see how she does.

DamoRC
Atta boy! How is the CG with the bare air frame (less nacelles)? Also, what type of foamboard do you use? Weight per sheet?
 

DamoRC

Well-known member
Mentor
#18
Atta boy! How is the CG with the bare air frame (less nacelles)? Also, what type of foamboard do you use? Weight per sheet?
Right now its balancing around 5 inches behind the wing leading (measured at the fuse)

Airframe weighs 6 oz (170 grams)

I am using dollar tree foamboard. 5 sheets is ~575 grams (20 oz) so ~115 grams (4 oz) per sheet.

DamoRC
 

Namactual

Well-known member
#19
Wow, that looks like it's going to be a rocket!

The intake is going to be an issue though, even with cheater holes. You might try a 3D sublet and a reverse cone around the circumference of the fuse section just forward of the EDF. From a distance you wont even know its there, and it will have great airflow.
temp.jpg
 

DamoRC

Well-known member
Mentor
#20
The intake is going to be an issue though, even with cheater holes. You might try a 3D sublet and a reverse cone around the circumference of the fuse section just forward of the EDF. From a distance you wont even know its there, and it will have great airflow.
Yep - an EDF version of this is going to be full of holes to allow the EDF to breath. I really like that idea of the reverse cone thingy - it looks cool and could do the job.

I decided not to do the pusher, but cram a 70mm EDF in there instead (one of my older Diamonds was getting towards the end of shelf life anyway). The EDF I pulled out has the lip taped on, so I removed it and crammed the EDF into the fuse (technically it does not fit, so I had to split the fuse, install the EDF and then re-glue the fuse). Now it looks like a small snake that swallowed a large rat!

I cut cheater holes into the canopy but was only getting 16 oz static thrust. So I cut some more in the lower portion of the fuse close to the EDF and I'm getting about 20-22 oz. So the EDF is still starved for air and there is no real "control" of the airflow going in. The AUW is now 25oz (with the EDF, a 2200mAh 4S, and all the other hardware installed) so it should have enough power to fly.

Will find out tomorrow.

DamoRC