Kit #401 bf-109 rubber powered, free flight

[Bluesynk]

So I am committing to crashing the next model. First time flier. Never have the Heart to do this to my corsair or p-38, they are way to heavy anyway.

I got a nice vintage bf-109 kit has the pilot, order form says march 1971, no age or modele reduit or bar code. has nice wood for the most part, the tail and rudder are super heavy but will be replaced anyway.

Hope it's a good flyer, has plans for extended wings, flat bottom, not a lot of plastic.

This will for sure be rubber powered. Not sure if I should use the nice red rounded 7" from this kit or the square black 9" from my corsair.

Have to decide between free flight and control line. Sorring free sounds satisfying. Controlling up and down in a circle sounds fun.

First time things in this build im looking at:

Build light. I have always built with testors wood cement and doped with elmers. That should be ok, going to concentrate on using less wood. Plan looks good for removing odd number wing ribs, te is thick will scallop those way back, remove the center section of fuselage keel over the wing, and make sheetwood tail section. holes in ribs and formers.

Removable wing. Should be easy enough, some nylon screws and small balsa blocks. First time crasher, will Probably need to replace the wing at some point.

Nose block. Want to be able to adjust thrust angle, stretch wind the rubber. Need to look at more of these, some pretty different stuff. Dont know anything about rubber, winding, stooges, or tubes either.

Planking. Strong but heavyish. Gonna crash, want it around the cowl and a spine back to and over the wing.

Control line. Can this be done well with rubber? Can you still swing it around when it unwinds? Big big nose weights?

Any insight in any of these areas would be great, im doing my research, but tips straight from builders are way better.

[WIDDOG]

Sorry I never built a 400 series kit for rubber power or U Control. As a kid I remember I built a 400 series Zero and flew it free flight with a Cox 0.020 motor. It did fly one time and crash landed and wrecked out. I than took a 20 year break from modeling.
Anyway for first time rubber power model I would recommend a 900 series kit to start with. They are designed sololy for rubber power. Also a nice feature is that when a 900 series kit crashes it can usually be repaired with a hot glue gun.
One thing I know for sure the kit rubber and prop are very unsatisfactory. I would recommend, for the 900 series kit Tan rubber. Also I would recommend 6 and 7 inch Peck Polymer props.

[BillParker]

The 109 and the Spitfire are tail heavy, built to plan, unless you bolt a motor on the front end. If you go u-control, (roundy round) just be sure to put the belcrank where the plans says to put it, and it'll fly well. You can also do a really nice paint job on the roundy round plane. Rubber needs a really really light version of the build...

bp

[Mitch]

I have built the 400 Bf-109, three times in the past 2 years. All for free flight.

Here are my suggestions:

1. Follow plans for extended wing
2. Drop half the wing ribs
3. Increase the wing dihedral to just below the canopy
4. Add a little washout to the wingtips
5. Make the front end adjustable for thrust
6. Move the rear peg forward one bay

You can use the 7 inch kit prop and kit rubber, I have done so and have modest flights in schoolyard. For longer flights use tan rubber and more of it. I use a 9 inch Peck Prop.

You can find a few build threads I have on here as I built and flew 2 Bf-109's and flew them at WESTFAC 4 and WESTFAC 5.

Mitch, Good Luck and Good Flying

PS: My last build, 400 FW-190, I used kit paper, sealed with spray dope, then painted with rattle cans. I think it looks better and did not add much weight!

[Bluesynk]

Thanks for the replys, ill be checking out some of your builds tonight.

Been working slow. Real nice kit. Just about all the parts fell out while sanding the backs. Only die crushed in 2 small spots.

Going free flight for sure. So building light. Started with the wing ribs. Been playing with a few ideas. If I only use every other rib, I thought maybe only use the larger ribs. It does change the rear angle on the wing but scale isnt a big deal to me for this project.

Maybe or not? Opinions?

[Mitch]

Follow the profile. You can use all the ribs if you like. It will still fly. You want it to look like a 109. The first model I built 2 years ago I have the shorter scale wing and that flies also. The 109 was a very small plane.

Did you cut out lighting holes in the ribs? Very good if you did but these ribs are so small I do not do that for the 109. Be careful working with ribs that are lightened. They get very delicate.

[David Lewis]

If you increase wing area, it's normally also necessary to increase horizontal stabilizer area in the same proportion. A relatively large stabilizer is a good idea on a tail heavy airplane. I locate the CG as far back as possible consistent with adequate stability.

[Bluesynk]

So got some work done. Off the pin board. Had fun with the light build. Might of got carried away but had fun with it. Some pics

[Mitch]

Okay... you are addicted to carving away balsa, be careful. The pieces are going to be very delicate now. I would not have bothered lightening up fuselage frames forward of the wing as you will still need to add weight to balance the model.

On that note if you can shave off 1 gram off the tail you will save 3 or 4 grams of ballast due to the moment. Moment = Weight x Distance.

Do you plan to fly with 7 inch kit prop? I have done so, for competition I fly with 9 inch peck prop, and for that I have an adjustable front end.

Mitch

[Mitch]

I see you need to shape the LE of the wing. Be careful as you have a nice delicate structure now.

Another note... I see you changed your wing profile. So now you have an experimental 109. I believe you would be disqualified for FAC scale, as your model should conform to the plane. Or at least the plans. They have no objection to my longer wing 109's as that is on the plans. I believe there was an experimental H version for High altitude that had a longer wing. That would be even longer than the plans show.

Will like to see your finished plane and your flight results!

[Bluesynk]

They are the extended length on the plans. Just the angle of shot. No other changes.

Dont know about le shape. Guidance would help there.

Have some more work done. Figured out the removable wing idea, and decided to carve a nose cone. Really happy with the nose, it moved the cg almost perfect so far. Used the plywood motor mount, cut out the dot to dot for cox mounts to align the cone. Will work in any guillows front end for a quick field swap too gonna make a few of these.


For the wing I just used square stock up front to hold the wing, the back attaches with a rubber band on dowel. A good jolt will let the wing loose maybe help in a crash and make travel possiable. Might replace with magnets

Pics!

[Mitch]

The carved front end looks great. The model looks so delicate like a real competition model... except for the tail. With so much work done on removing wood your tail looks heavy. I like to keep the thickness of the tail and remove some wood from the inside as you did on the TE of the wing. Latter you can start making bent balsa tails and the will be lighter and stronger, keeping the thickness you want.

I like the removable nose block, but you will also learn to have that opening large enough for a blast tube during winding. But this was your first model and it is coming out much better than my first (recent first) 109 I built about 2 years ago. My first 400 series 109 I built when I was about 14 and it weighed about a pound.

When I make removable wings I use rare earth magnets... and yes they helped in a crash. But you have to be careful not to move the wing during launch... that will cause a crash. So I guess it can be a double edged sword.

Did you move, or are you going to relocate the rear peg?

Your skeleton looks GREAT!

[Bluesynk]

Got the tail shaved down today.

Moved my cg forward an inch, so ill bore some holes in the back of the nosecone

I do plan to move the rear peg forward as well. Been reading up on motors. Thinking a 4 or 6 strand braided motor.

[Bluesynk]

Had a chance to weight it today. With plywood firewall 30 grams, with nose cone and prop 53 grams

[Bluesynk]

Quick pic