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FTCC'18 WWII Fieseler Fi 103R Reichenberg

Namactual

Elite member
#41
That looks great! Already Flite Testing too. I am WAY behind.

I am not sure how it would look, I am trying to picture it in my head, but maybe just try to tweak the nozzle a bit to give you the thrust angle you need. Something like the A-10? I am trying to picture a 3* bend at the end. It might not look too bad?
 

PsyBorg

Wake up! Time to fly!
#42
How scale is your model actually to the real thing when considering the distance above the main wing. I know with other aircraft the higher the power is above the wing the more thrust angle it takes to correct bad tendencies. Look at the high mount motors on things like the Explorers and Bixlers, or even the older pusher style flying boats.

The side view in your original picture shows (by eye) the angle to be closer to what the 2 degree representation you just posted appears to be.
 
#43
Thanks for the suggestion Michael. If you were to build an adjustable setup, this seems like a good way to go.

I would like to build the "tweaks" into the current plan to make it easier for folks to build. I looked at the thrust angle ranges you suggested just to see what it would look like (in Sketchup)
DamoRC,
I figured the adjustable setup would be for the prototype only. After the adjusting, testing, repeat sequence, you would know what angle to put into your Beta plans. and go from there. I like where you are heading also, sorry for not being clearer in my original post.
 

DamoRC

Elite member
Mentor
#44
That looks great! Already Flite Testing too. I am WAY behind.
Nah - you're not way behind, I just let my over-eagerness get the better of me. By taking a very simplistic design approach in sketchup and a pretty basic build approach I was able to move to a flying bird pretty quickly.

I am trying to picture a 3* bend at the end. It might not look too bad?
Thanks - another solid technical solution and I could definitely model the rear part of the exhaust to do this. Initially I thought that this would be too tricky for other builders (i.e. having them check this angle which by eye would be harder then just getting them to confirm that it was straight). But if I model the part that way and they assemble the pieces correctly (i.e. the glued seam of all the tubular sections is at the bottom and lines up between all the sections), then the angle will be there and will rely on how accurate they cut the part.

How scale is your model actually to the real thing when considering the distance above the main wing.
It's pretty good. The only significant scale "deficiency" in the model is the fact that I modeled the rear of the plane to be symmetrical top and bottom (which is not the case in the real model) and the details of the canopy.

The side view in your original picture shows (by eye) the angle to be closer to what the 2 degree representation you just posted appears to be.
I tried measuring this angle on the picture a few times but the tube does not seem to be 100% symmetrical so I got values of 0 degrees to about 3/4 of a degree down thrust. But you are correct, if you stare at it long enough there seems to be a down thrust angle in the pic. So I tried a different approach by overlaying the various thrust angle models over the three view profile and it seems that a 1 degree down thrust is about right.

Thrust angles over three view.jpg

So I will model in 1 - 1.5 degrees down thrust

DamoRC
 
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DamoRC

Elite member
Mentor
#46
Quick update.

Took her out today with the modifications made (Lowered the EDF by 1/2 inch and added the 1 degree down thrust to the pulse jet). Tried her first on a 3S 2200mAh because she flew okay on 3S last weekend. Not this weekend though. I think she was a little tail heavy and the lower thrust from the 3S combined with the mods to remove the push over effect (which mask the tail heaviness issue) resulted in her flying terribly and I had to dump her. Split the fuse along one of the section joins. But some hot glue soon had her back together.

On 4S she flew well enough and the push over phenomenon is greatly reduced. Also, 4S 2200mAh helps with the nose weight because I could cut the power to 30-40% and still fly around reasonably comfortably.

So I think she is done. Couple of things to fix (need a better battery tray design, a tougher HS, and a cleaner elevator servo setup). Then I will make final set of plans, a proper final build based on these plans, and one more vid of the plane in the air.

DamoRC
 
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DamoRC

Elite member
Mentor
#49
How does the speed compare to the Ohka? Can those two place nice together?
Hard to tell from the vids but I think the Ohka is faster in terms of how fast I was covering the field. It wouldn't surprise me based on the difference in weights and size of the plane. I think the Ohka is capable of more with proper inlets, maybe a thinner wing (like an NerdNic wing) and a proper thrust tube.

DamoRC
 

DamoRC

Elite member
Mentor
#50
Been a while since I updated this project. Finalized the plans and built this version from those plans.

Final at the field.JPG

And this is the maiden video (a little short, but proof that it flies I suppose).



I set her up tail heavy to counter the push over from the EDF. I also built in some throttle elevator mix which I could turn on and off. I had to turn it off shortly after launch because I had way too much elevator compensation. As it turned out, the push over effect was far more manageable than I thought without the mix.

Now that its done (I will add a build post soon), I think I am going to pull the EDF and make her a tractor. She looks pretty good and flies okay but the push over phenomenon is always a worry.

DamoRC
 

DamoRC

Elite member
Mentor
#58
Thanks Guys. Looking at the vid, the launch seems so much more relaxed than it actually felt at the time. I was pretty sure I was going to drive her straight into the ground.

The paint job effect was luck and not skill. One of the more common paint schemes I have seen for this is sky blue on the bottom and dark green on the top. You can just about see the blue on the bottom in this pic.

IMG_2947.JPG

I have been trying to paint with lots of very light coats of spray paint to avoid wrinkles in the paper / foam. I was about 4 or 5 coats in when I thought she was ready for a final heavier cover coat. But at this point she had a nice mottled / camo effect going on, so I didn't apply any more. So the final finish was by chance and not by design.

DamoRC