BF-109 F (Scratch Built)

[TVCasualty]

Let me start off by first saying thanks to all those who have posted build logs on other scratch built aircraft, as I have found all these posts to be priceless sources of information. For that reason I decided to share this one so that others will profit in the same way from my experiences and mistakes...

Goal: Build a foam RC aircraft with retractable landing gear (GWS micro type).
Outcome: A very nice looking RC aircraft without retractable landing gear.

So I started off grabbing some 3 view drawings of a BF-109 F. The site I liked the best was this one which has great drawings of all sorts of WWII aircraft: http://www.penio.narod.ru/

This is my third build and I wish I had known of that site for the previous bird.
From that point it was conceptualize and draft.

The fuselage is made from fan folded foam, rolled while being heated with a heat gun (a hair drier will work but takes much longer, but is more controlled). The important step in rolling a fuse is to cut relief cuts in the foam which will melt and form a type of strut, while limiting the internal stresses formed from bending the foam. The first plane I had built needed the fuse remade as it tended to pop apart on anything other then a feather landing.

Once the fuse was rolled I measured and crafted templates for the nose area. If I had to do this over the entire nose would have been of different design as with the weight of the motor it proved to be much too heavy and made a very impressive crash on the maiden test flight.

The wings were made with the wire cutter and template method as found on this site:
http://webpages.charter.net/rcfu/Con.../FoamWing.html
Note I didn’t bother with the floating wire cutter and all that, but my wife was very helpful… Once the templates are made a wing takes under an hour to pull out, counting painting time, it a really quick process.

Attached are some pics of the starting process.

[TVCasualty]

Rather then just throw out the scrap foam from the wings I built a plane stand with a stick of hot glue and a knife. This was one of the better moves I made making this model. However the level seen on top of the fuse, that was a mistake. Rolling the FFF makes light construction but proves to be not accurate, at least for me… The wings ended up off, so I had to re-trim the cutouts, ok could have been worse. A better way was to hang a string from the CL and match it with a mark designating vertical, then use the level to making sure I had a reference point. The wings fit nicely, on my last model I made the wings permanently installed. Seemed to me that this would make storage a problem so nylon screws and T-bolts it was… Was being in the past tense. Another mistake as this causes stress to be much too high for the FFF walls not to mention the limited space inside the body needed for mounting all sorts of other things. The T-bolts were removed and the wing was remounted permanently which greatly strengthened the airframe. The nose was also made out of foam and run through the drill to make sure it was smooth (and balanced). Used the wire cutter to slot it for the prop.



Dropped on the rudder.

[smokejohnson]

Nice start TVCasualty, it's looking nice. Looking forward to seeing more pics.

[TVCasualty]

At this point it was starting to take shape. The remaining parts were simply cutout of more FFF and were trivial next to the rest of the model. Worth mentioning, is the fact that the tail servos were direct mounted instead of using control linkages, this makes things quicker and works better. The aileron servos were made using the traditional torque arm method. ...And then the process of the retracts started. Retracts on a 109 are tough, GWS retracts on your second build are crazy tough since the actuator faces the wrong way. Further more the set screw provided with them is worthless. Once I had them installed and working, the innards were installed and they collapsed under the weight. Since I spent more time messing with them then building all the other planes I have combined I decided to ditch the effort. The motor was mounted to EPP foam, not EPS, sandwiched between a piece of plastic and a piece of flashing tin. Since the only force on the motor mount is compressive all you really need to do is keep it from pulling out the front of the aircraft. The screws in the front allow me to adjust the thrust angle and the elastic nature of the foam allows for “rough landings.”

[TVCasualty]

So speaking of rough landings The test flight after the plane collapsed under the retracts proved all the mistakes made in construction. The plane flew great but was on a collision path of something I’d rather not say due to the fact the AMA may try to hunt me down. The result was an intentional nose dive into the ground at about a 30 degree angle. This was better then the alternative and made a spectacular crash and showed that the idea of a detachable wing was a worthless idea for this model as detaching it was a nightmare anyhow. The ability to repair foam is amazing, and I can’t imagine trying to learn to fly on balsa. The nose was then rebuilt with clear duct tape and large piece of EPS foam. I wish I knew where to get more EPS readily; I can only say I got mine as industrial waste. The EPS in nearly indestructible for RC purposes, and the nose was completely packed with the stuff. After I made these corrections I also fiber glassed certain parts for more durability on belly landing and to reinforce the wings. More details were added such as the air intakes and the exhaust pipes. The “foamies” poster board foam was bought from walmart and used for the flashing on the wings and other subtle details.

[TVCasualty]

We tossed it into the air before I painted it just to prove it would still fly.

[wilmracer]

Very nice! Looks great. What is the span on her?

[CHELLIE]

Hi TVCasualty and Welcome to Wattflyers,very very nice build, it sure is nice when, after you build a plane, and toss it in the air, and if Flies great, thats a great feeling, keep up the good work, Chellie

[TVCasualty]

Thanks guys!
The span is 45 inches, and it has two speeds... fast and stall.
Flying weight is 27.7 OZ, 7 OZ of which is a 9 cell NiMH battery.

I'm using the 500XTH motor from milehighRC and it is a power hungry monster. The battery quits at about 1/2 throttle giving up as much juice as it can at about 10 Amps with a 11X7 GWS "HD" prop, or the 1170EP. Even still 1/2 throttle is more then enough to get this bird into the air.

Sadly I'm on a fixed course to upgrade to Lipos to get the most out of the motor. I have some new pics of it painted, but left my camera at my uncles.

[TVCasualty]

While it was cool to have the only pink Messerschmitt on the block, my airbrush needed cleaning out since the last time I used it. My wife has scolded me for posting pics of the garage in the state it’s in, but it shows the struggle I had in finding it in the first place…
Now is as good of time as any to talk about the problems I’ve had with this bird once it gets airborne… The tendency to tip stall is unbelievable. It has crashed heavily on take off several times already. Mainly it pulls sharply to the left and I’m left to try and level it out and pull up. Part of the problem is the size of the rudder, which I believe is too small, and its actual position. The sharp pull was corrected by trimming the rudder to the right. Not a big deal except due to the thrust angle being so high (which I can change once the nose cone is removed) at lower speeds the motor tends to pull the plane nose up, then it’s soon back to the tip stall since the plane tries to climb. The last time I took it out today I suddenly lost control of all tail functions and I’m hoping it turns out to be some unplugged servos, thankfully it landed quite gracefully. Since the design changed after the first “rough landing” it’s difficult to get to the receiver. Better planning on where and how to access things upfront will save a lot of time latter on. So much as you stick to the plan.

Foam does not like stress concentration factors.
Any sharp cut angle, any hole, or any point that supports a large surface will have a very high tendency to rip out on a crash or even heavy landing. Fortunately it is very easy to fix these breaks, but a better approach would be to avoid these all together. And when that is not possible, reinforce the area with tape, or better yet fiberglass (BUT DON'T USE BONDO!!! use the zap stuff that's foam safe). A hard point can be installed, but if all one is a point, expect it to get ripped out.

With all that doom and gloom being said, I am certain I can fix the remaining issues without too many problems and we got some really great pics today of it in the air as even with all the issues it is still very flyable.

[aviatordave]

Good build, very interesting.

Once you go to brushless/lipos you prob wont look back.

Any way to show video of the launches?

[TVCasualty]

Sadly, I don’t have any video of it being launched. I can describe exactly the conditions however. One attempt there was a strong crosswind blowing in the direction that the plane tipped, however to make matters worse, the plane was launched at much too steep of an angle, compounded by the strong thrust angle pulling it up, instead of forward. Had there not been a chain link fence blocking the new vector, the launch would have been just fine as I did level out the plane… On other occasions with no crosswind, where we were launching into the wind as we should, and the angle was closer to level flight, the plane took a sharp left about 5 yards from the release point. This crash put the plane on its nose, popping off the nose cone, as I did not have the altitude to correct. The last launch where I had re-trimmed the rudder was perfect, and there was no wind. However I had lost control some time into the flight when the tail controls went out. (Dought!) As far as the throttle goes, as the motor is a brushless and is very powerful, it does not seem to matter if it is full, ½ or even a bit over ¼. The plane manages to leave in a hurry, where I suspect the actual torque may be pulling it to the left as well. Remember, fast or stall… :/

But as a lesson I believe to have learned, I would highly suggest that if you are building a model from scratch not using any plans, and the rudder looks a bit too small it will not hurt to scrap it and make a tad larger one. This will help with tip stalls and to a small extent with rolls, but will make snap rolls more difficult to make happen. Sometimes when trying to build a scale model, you’ll look at it and not quite be able to put your finger on what is wrong. It helps to ask someone for an objective opinion… I plan on fixing the thrust vector and trying again, but I may end up increasing the rudder size in the end. Good thing its only foam.

[SaucerGuy]

Originally Posted by TVCasualty

So speaking of rough landings The test flight after the plane collapsed under the retracts proved all the mistakes made in construction. The plane flew great but was on a collision path of something I’d rather not say due to the fact the AMA may try to hunt me down. The result was an intentional nose dive into the ground at about a 30 degree angle. This was better then the alternative and made a spectacular crash and showed that the idea of a detachable wing was a worthless idea for this model as detaching it was a nightmare anyhow. The ability to repair foam is amazing, and I can’t imagine trying to learn to fly on balsa. The nose was then rebuilt with clear duct tape and large piece of EPS foam. I wish I knew where to get more EPS readily; I can only say I got mine as industrial waste. The EPS in nearly indestructible for RC purposes, and the nose was completely packed with the stuff. After I made these corrections I also fiber glassed certain parts for more durability on belly landing and to reinforce the wings. More details were added such as the air intakes and the exhaust pipes. The “foamies” poster board foam was bought from walmart and used for the flashing on the wings and other subtle details.

I can get truckloads of EPS locally, I cannot get fanfold to save my life and refuse to pay some huge mark up from an online retailer for it. I too am a builder in foam and I've never had the chance to work with fanfold but would really love to. PM me, let's work something out here, I want fanfold, you want EPS, need I say more!!!

Great job on that build, that plane looks really sharp! You are correct on the tail feathers, both of them, I'd increase them significantly, sure you can get it to resemble flight with smaller ones, but it doesn't last very long as you found out. Making them too large will not hurt you, making them to small will turn the plane into packing material quickly.

[TVCasualty]

Originally Posted by SaucerGuy

I can get truckloads of EPS locally, I cannot get fanfold to save my life and refuse to pay some huge mark up from an online retailer for it. I too am a builder in foam and I've never had the chance to work with fanfold but would really love to. PM me, let's work something out here, I want fanfold, you want EPS, need I say more!!!

Great job on that build, that plane looks really sharp! You are correct on the tail feathers, both of them, I'd increase them significantly, sure you can get it to resemble flight with smaller ones, but it doesn't last very long as you found out. Making them too large will not hurt you, making them to small will turn the plane into packing material quickly.

Errr...
That’s what I get for not referencing my building with foam book before I start rambling. I actually meant EPP, extruded polypropylene, or the stuff that some pool toys are made out of. I’ll go back and correct the original post… EPS is the typically white stuff that is made up of the little beads. I can get plenty of EPS, for dirt cheap at the local Home Depot.

Now the FFF stuff I have is about a year old, I picked it up from Menards, as HD or Lows don’t seem to have the same stuff currently, they got a poor finished very rough looking replacement, that I’m sure would work fine for insulation, but not airplanes. The problem is I don’t get out to Menards often so I’m not 100% I can still get the stuff. If I make it back there sometime soon I’ll shoot you a PM on how much it’ll cost for what.

[CHELLIE]

Originally Posted by TVCasualty

Thanks guys!
The span is 45 inches, and it has two speeds... fast and stall.
Flying weight is 27.7 OZ, 7 OZ of which is a 9 cell NiMH battery.

I'm using the 500XTH motor from milehighRC and it is a power hungry monster. The battery quits at about 1/2 throttle giving up as much juice as it can at about 10 Amps with a 11X7 GWS "HD" prop, or the 1170EP. Even still 1/2 throttle is more then enough to get this bird into the air.

Sadly I'm on a fixed course to upgrade to Lipos to get the most out of the motor. I have some new pics of it painted, but left my camera at my uncles.

Hi Tv try this motor and lipo in your plane, it will fly a plane thats up to 48 OZ has 30 OZ of thrust, and will turn a 11x7 prop, and its inexpensive, its the towerpro 2409-18 Direct drive outrunner, Heads up Rc has them, here is there link, also a 2200mah 15c 11.1v 3 cell lipo, take care, Chellie

tell Jeff at Heads Up Rc that, Chellie sent you

http://cgi.ebay.com/2409-18T-Outrunn...QQcmdZViewItem

http://cgi.ebay.com/Lipo-Battery-11-...QQcmdZViewItem

[SaucerGuy]

When I first upgraded to brushless I was impressed, not jumping for joy, but was happy with the performance boost, when I upgraded to lipo's in combination, all of my planes changed overnight. You'll like the move big time, it will then be a matter of trying to slow it all down, they aren't kidding when they say they will fly a brick.

[TVCasualty]

Thanks for all the advice guys.
Truth be told, I just started flying this summer thanks to the parkzone warbirds. I just couldn’t pass up flying one of those for just under $200, bought a spitfire and haven’t looked back, although the salesman swore it wouldn’t last long if I was going to learn on it. Well it taught me just fine, and I picked up a FW-190 on ebay for $90 and bought a few more batteries to go with them. The steep learning curve quickly taught me that I was quite crafty building and repairing so I carved out a beautiful P51, but I wanted it indestructible, and the fiberglass just made it way too heavy to practically fly (especially for it’s size). I chalked it up as a learning experience, and built that blue hellcat looking plane seen in the background concentrating on making the airframe as light as possible. The hellcat weighed in at just over 7oz before the equipment and flies like a dream (after I increased the rudder size).

Which brings me to my point… lol
In the hellcat I used a really nice motor again from milehighrc called the 450XT. It’s also about 1000kv, and pulls about 10 amps with a GWS 1060EP (10x6 HD) WOT. But it allows me to fly for about 20 min on the same batteries that I bought for the parkzones with conservative throttle. Only issue with the 450XT is that if you crash badly, and bend the motor shaft, you would have to replace the entire bell housing of the motor. This has not been an issue however since I’m using a flexible mount as I have done with the 109. The decision was to go with the larger 500XTH motor, since it has a removable shaft, and because it has a higher KV rating for more speed. It will be a dream if I use a larger battery since it has the potential to pull over 3 lbs of thrust, but I’m reluctant to use lipos. In hind sight it is way overkill for the 109. I’m waiting and hoping for more info and availability on the newer LiFePO4 batteries since they don’t catch fire and explode…

As an update, the corrected thrust vector really helped with the tip stall issue on turns. The rudder is chalked up to be enlarged, however the plane is un-flyable at the moment due to a high speed run in with a notorious but tempting soccer goal where I fly. Again, a very impressive crash (the best kind)! Watch some old WWII gun cameras and you’ll get the idea… Too bad I don’t have video of it.

I’m putting it on hold for a bit to use the receiver in a new project I’ll be starting on Tuesday using a smaller motor and 8.4V power supply.

[TVCasualty]

Another great day to fly over here...
I rebuilt the 109 rudder making it a tad longer, and changed out those ole NiMHs for a hot A123 setup.

This thing is nuts.
The motor can use a 4s setup, but I tried out a 3s today, and decided that it was plenty of power. Made a 20 min flight time in light to no wind with the flying hopefully included in a attached video.
With a 4s pack this things climbs like a model rocket.


poop the video didn't work.
I'll get it on youtube later.

[TVCasualty]

YouTube Video

[TVCasualty]

Wow, after taking the winter off to work my day job I finally got back to the garage to work on my planes again. I'm still flying this 109 and today I tried it out with the new VPX Black and Decker cells in a 3S configuration. The cells cut down on a lot of weight for this bird and made it a blast to fly. I picked up a 10 min flight, flying conservatively, and the cells were a little warm upon landing (figure no airflow past them in flight & surrounded by insulation). Also I made a canopy for the 109, this was exciting for me as I learned that it IS possible to vac form using plain old pink foam as the mold (don't expect more that ONE draw) and re-enforcing sharp corners is a must if you want them sharp, and some kind of release agent is also a good idea. It has it's limitations but for a quick mold, I've gone pink. My pops got some great pics of me flying...

I am now going to focus entirely on getting my SE5a back into the air with these new cells as they are about 100g lighter then the old NiMh supply I was using.

[firemanbill]

Looks great TV!

[Grasshopper]

Awesome! Nice pics.

[soar-ne]

TV
If you have room for 4 of those cells try them. That is about equal in voltage to a 3 cell lipo or 8 cell nimh. I have been useing them to replace 8 cell nimhs in a smaller sailplane(HOB 2X4 with power pod) You will have extra power on hand and longer duration because you can throttle back some and still fly at the same speed. I run 2--2cell packs in series, 2 cells in the nose (skinny-small area) and 2 in the ballast area under the COG. They are great cells and can really put out the juice Great Looking 109 also!!!!!!!

Happy Flying
Bob

[Voyager2lcats]

Okay, I am unveiling. I have been trolling this thread and am now coming clean. Very nice Bf-109. You did a nice job on the painting. I really like your photo of it in that right bank- classic! Keep flying.

Bob

[firemanbill]

Originally Posted by Voyager2lcats

Okay, I am unveiling. I have been trolling this thread and am now coming clean. Very nice Bf-109. You did a nice job on the painting. I really like your photo of it in that right bank- classic! Keep flying.

Bob

I think the word you are looking for is "lurking", not trolling!

from wikipedia

Troll (Internet), a person who is deliberately inflammatory on the Internet in order to provoke a vehement response from other users

You are certainly not trolling Buddy!