BF-109 Swapperschmidt

[Black Knight]

Well done mate, just a couple of bugs to iron out and it will be a sweet flying unit

 

[earthsciteach]

I had the same problem with my 800mm FMS Spitfire. I made many mods which improved, but never eliminated, that nasty behavior. First question - what is the wing loading of this plane?

 

[Onebladeprop]

to be honest I'm not really sure how to calculate the wingloading. the surface area is 93830mm(according to sketchup (wingspan 790mm, root chord 145mm)) and I want to say the model weighed 450g with battery, but I'm not sure it's right. When I get the next one done I'll weigh it and post the weight so I don't forget.

ok according to this http://adamone.rchomepage.com/design.htm#calculate
at 450g it would have been 39g/sq.dm or 12.91oz/sq.ft

as long as I wasn't giving it a much elevator it didn't seem to fly like it was very heavy. it felt lighter than my fms 800mm corsair.

 

[earthsciteach]

Its one of those weird things. I think my Spitfire suffered from high speed stalls which caused it to snap roll. But, the wing loading wasn't excessive. Could have been due to the airfoil and elliptical wing. Maybe it was because of a lack of downwash at the wingtips (doubt it) or maybe the horizontal stabilizer deflected unevenly under the load of up elevator (i'm leaning toward this in my case). Either way, it is a royal pain in the arse to fly!

 

[Onebladeprop]

I built another plane with the horizontal stab down in a more conventional location on the fuse and put the elevator servo on the other side. This time it rolled hard left, but something felt different. This felt more like torque roll than the phenomenon I was getting before. It was much more violent and didn't seem to matter how much elevator I used. After I brought it in I sat the battered plane down and gave it some thought. If it's torque roll then some thrust angle should fix it just fine. Not wanting to build yet another plane just to try this one idea I decided to glue the broken pieces back on and reinforce them with popsicle sticks. A couple of washers for the thrust angle and I was ready to step outside. Unfortunately right now it is the rainy/windy season. As soon as I crossed the street the wind picked up and a sleet storm started. The wind was 15mph gusting to 22mph. I didn't even care, something was going to happen today... The plane flew. The wierd rolling was gone completely but the plane did feel tail heavy. As the wind and rain picked up the paper got wet and the wing started flexing really bad not to mention I was getting cold so I brought her in for a safe landing.

I've already printed off plans for another one of this same prototype. I want to confirm my results then build another with the stab back in it's proper place. I have some ideas for reinforcement that will hopefully work. Progress has been a bit slow lately but there has been progress


the look of success

 

[Foam Addict]

This looks promising!
Can you get a high (1800) kv motor and get to a smaller prop?
It won't accelerate as well, but it might not torque roll either.
After thinking about it, the real 109 had quite a bit of thrust angle correction to.
I really like this plane and its progress.
Now all you have to do is put a fire cracker in this prototype!
Kidding.

 

[Onebladeprop]

That episode was hilarious! The thought has crossed my mind, I already have the components laying around...

 

[eagle4]

Mate, this is coming along really well. I'm loving seeing your updates and progress. I wonder if you'll get this design nailed first before the FT spitfire gets released. keep it up mate

 

[Onebladeprop]

I got the latest version built sunday and the weather broke long enough for me to get a flight in today. I need to rake the gear forward more because this plan loves to be nose heavy. The elevator still seems to washout a bit but now it doesn't seem to prefer one side or another. I may have to end up with the larger tail feathers in the final version(this one has the "scale" size). When you hear the RPMs drop that's about when I dropped the flaps, and boy are they effective. I hope to have the plans released by or around the time of the spitfire. Thanks for all your support and advice everyone!

 

[Foam Addict]

Excellent work.:applause:
I cannot express my pleasure that you were willing to carry through with a design that had so many problems at first.
I can't afford to build much, but I will definately try to build this one.

 

[Onebladeprop]

Now I'm feeling pressure, I hope it lives up to your expectations.

 

[roger5005]

If this becomes a Kit, I will definatley buy it...............

 

[LordVader]

Did you ever get to finish this build. I would love to give this bird of prey a try. Ultramicrobe designed one and I built it. It flies great. I am always looking to try several versions of the same plane.

 

[hursto75]

I built a BF-109 from some plans i found on the flitetest site. Here is what it looks like, I have a triple prop for it, just waiting for the motor.

 

[eagle4]

Wow. Looks fantastic mate. Great paint job too