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Old Oct 03, 2004, 05:02 PM
Glue can fix that.
Brutus's Avatar
Sunny Miami
Joined May 2004
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Sig Fokker D-VII pictorial Build Modifications

This thread will be similar to the TM-A, (tiger moth aerobatic) http://www.rcgroups.com/forums/showthread.php?t=250326
in the sense that I will add ailerons the the fokker. I won't go into as much detail, just where I change things. I will also mention mods that have been done by others in this forum. Hope it is helpful. Please feel free to comment.
Below is a pic of the TM-A and the advertising shot of the fokker from the box.
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Old Oct 03, 2004, 05:08 PM
Glue can fix that.
Brutus's Avatar
Sunny Miami
Joined May 2004
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Here is something I will do differently. I plan to build the whole plane without epoxy. I will only use liquid nails,as shown below and foam safe CA. Though this should speed up the construction, I am kinda busy with a new job so it may go slow overall.
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Old Oct 03, 2004, 05:44 PM
Hooper, full throttle!
Tommy D's Avatar
USA, NY, East Islip
Joined Feb 2004
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Brutus

This is PERFECT timing for a buddy whom is just starting to put his Sig Fokker together. BTW the moth in the other picture looks great. Is that a 400 sized one? With all that control surface it must have really been a noticeable upgrade! I like the single strut as well!

I posted a photo of the wing incidence on my Camel in the other thread, thanks for the suggestion. Dropping the lower one helps kill some of itís ballooning. I hope to fly it again soon after lowering the upper one now as well.

Regarding a general question on adding Ailerons. I have a little Hanger 9 E III <NOT the Wattage kit> I would like to build with a set of strip ailerons. Whatís the general opinion on the size to employ when adding strip ailerons? I had hopes of using a simple set of Du Bro strip kits and wanted to keep it as simple as possible.

I hope you donít mind me asking these questions in your thread but it seems you would certainly have the answers Iím looking for.

Best of Luck on the Fokker DVII itís always been one of my favorites!

Tommy
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Old Oct 03, 2004, 06:42 PM
Glue can fix that.
Brutus's Avatar
Sunny Miami
Joined May 2004
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Actually it is the pico moth.
The big ailerons take it from a lazy slow flyer to very aerobatic.
The single strut was necessary to accomadate the large ailerons.
This fokker will have narrow ailerons on one wing since I just want it for sport flying. Dual are needed for real aerobatics, and they have to be pretty big. I don't know if there is a formula. I just use experience--I guess.
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Old Oct 04, 2004, 12:03 AM
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Nevada City, California, United States
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i have a sig DVII i built a few months ago. one thing, keep it light. i painted mine in jasta 15 colors and it ended up 2 oz heavier than stock and it wouldnt fly. i've since put a 350 motor and a new gb in it. havent had a chance to fly it yet, but it should have plenty of power now. one tip, if you want to use AAA sized batteries, you can cut a slot in the compartment and slide it in vertically. this keeps the battery in place and if you put your rx under the servo tray, locks it in place. i dont think you can do it with anything bigger than a 730mah 7 cell though. oh, and you'll want to reinforce the tabs the lg have that go into the body, i just put tape on them and epoxy. would have been a great place for a little fiber glass work.
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Old Oct 04, 2004, 07:46 AM
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New Whiteland In.
Joined Mar 2003
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I have one that was all stock and had wing failure on the 3rd flight! I even had the packing tape on the wing per-instructions from Sig. Make sure you reinforce the wings. Mine was light but it never flew well at all,not a Moth by any means but then what is. I did find out that a GWS 9070 prop will help. It sure is a good looking plane,good hardware but a poor flier,at least for me. Good luck,
Roger
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Old Oct 04, 2004, 08:24 AM
Happy fly begin
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Joined Aug 2004
681 Posts
I have the SIG Fokker and it is a wonderful flyer. If you are going RET, add dihedral or it will be very twitchy to fly. I used carbon fiber tube to add dihedral, which also adds the needed strength. Also, get bearings for the gearbox, they come with bushings. Ditch the stock prop and use a 9x7 or 9x7.5 The etec1200 lipos fit in the battery compartment. I get 45-50 minutes flight time on mine. I have over 20 hours on it and have had no problems. It is not a moth, takes more hands on at all times. Does not fly as slow and is much faster then the stock pico moth.
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Old Oct 04, 2004, 08:04 PM
Glue can fix that.
Brutus's Avatar
Sunny Miami
Joined May 2004
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In response to all the great comments:
I plan to use an airbrush to keep down the paint weight. Plus the existing scheme is not bad. I agree keeping it light is key. I think I did a good job in the TM-A build thread using CF and fiberglass.
I definitely will reinforce the wings. These are the thinnest foam wings I have ever seen. I am sure they would fold with a few Gs.
I will change the motor to a brushless.
I will forgo dihedreal since I want good response from the ailerons.
I think I will use lipos in the battery compartment. They should fit well.

Here is a reinforcement for the elevator. I have seen wire used before. This is 1/16th carbon fiber rod on the leading edge.
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Old Oct 04, 2004, 11:08 PM
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oh yeah, thats another thing, the "tape hinge" that sucks. if i could redo it, i'd do ca hinges or crossover tape hinges with a tape cover, anything other than the way they tell you to do it. the tape doesnt stay stuck together and then you end up with a hinge that flexes way too much. meaning its even harder to control.
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Old Oct 05, 2004, 07:07 AM
Gravity is a harsh mistress.
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United States, MI, Temperance
Joined Sep 2002
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Quote:
Originally Posted by Catkicker
oh yeah, thats another thing, the "tape hinge" that sucks. if i could redo it, i'd do ca hinges or crossover tape hinges with a tape cover, anything other than the way they tell you to do it. the tape doesnt stay stuck together and then you end up with a hinge that flexes way too much. meaning its even harder to control.

You need to use the right tape and you will never want to use CA hinges again. 3M Blenderm medical tape is just right for a plane the size of the Fokker.
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Old Oct 05, 2004, 12:28 PM
Loose Cannon
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Deer Park, New York, United States
Joined Mar 2004
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Last night I almost wrapped up my build. From what Iíve read here it looks as if Iím in trouble. I am a newbie so I build to crash . I glassed all surfaces. I think being lazy paid off for once because I left the tail feathers as they were out of the box and glassed both sides. Once they dried I trimmed off the extra bits of foam and ended up with fiberglass hinges that are in perfect alignment.

I added dihedral but I wouldnít recommend the way I did itÖ. I accidentally took a lot of the airfoil out of the wings. I tried to introduce the dihedral from the cabanes outward. Iím at work so Iíll have to post a pic later but I tried for something like this: \_/ opposed to this: \/ very exaggerated but you get the idea.

Although Iím impressed with the quality of the kit and the instructions I suspiciously eye the motor and gearbox. With all the weight Iíve added Iíll likely need a GWS 350 too get if off the ground. Can you say ďUber FokkerĒ? Last night I started installing the radio gear. I feel like I need hemostats and needle-nose pliers.

One last question, I assume the battery compartment is the first opening towards the nose, am I correct? The instructions show the ESC and receiver occupying that space as well. It doesnít really matter too much as Iíll arrange the components <other than the servos> as needed to achieve the desired CG. But I am curious.

So far Iím pleased. This plane is so good looking Iím considering building a static model.

Brutus, good luck with your build & sorry for chiming in but I get all gushy thinking about the DVII.
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Old Oct 05, 2004, 04:42 PM
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Nevada City, California, United States
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Quote:
Originally Posted by tiberius
You need to use the right tape and you will never want to use CA hinges again. 3M Blenderm medical tape is just right for a plane the size of the Fokker.
well, silly me, i just used the crap they suggested. that and the fact that the foam is so flexable that even if i'd used better tape means its still going to fly like a drunk duck. i'm not real impressed by this thing at this point.

oh, and to the above poster that glassed his. there is no way it will fly now. i just PAINTED mine and it ended up too heavy. you're going to have to go to a much higher powerplant and theres limited room in the cowl for a large gb. might be a good time to look at brushless motors.
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Old Oct 05, 2004, 05:45 PM
Hooper, full throttle!
Tommy D's Avatar
USA, NY, East Islip
Joined Feb 2004
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Quote:
Originally Posted by Catkicker
oh, and to the above poster that glassed his. there is no way it will fly now. i just PAINTED mine and it ended up too heavy. you're going to have to go to a much higher powerplant and theres limited room in the cowl for a large gb. might be a good time to look at brushless motors.

Cat

I have read of your trouble with the Sig Fokker and am sorry to hear it. However I think you should be careful to paint with such a broad brush.

While I donít think that adding unnecessary weight to any model is a good idea, glassing is never a bad idea. Done properly you have a model thatís a lot stronger then stock and has minimal weight gain. Sig suggests a fairly heavy battery. So if Wind Slave uses a Lipo then there will be some wiggle room right their, weight wise.

Done improperly you end up with a 22+oz Wattage Sopwith Camel like I fly. Yet it still flyís with some authority and slows down to a gentile slow flyer. When I had a electronic failure at 30 feet and it augured in it survived.

So I guess what Iím trying to say is donít be surprised if Wind Slaves Fokker does indeed fly. Check the posts and you will see Sig Fokkers at or near 13ozs that still fly ďfighter like with authorityĒ.

Oh, and if/when you give up on yours send it my way Ill be glad to have it!

Best Regards

Tommy
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Old Oct 06, 2004, 05:36 AM
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i wish i could remember the exact weight mine was, i think it was 15.2 oz. a couple above the max recommended weight. i've since put in a 350 gws motor, i just havent had a chance to fly it, it should have more than enough power now. i'm still not happy with the hinges and wish there was a good/easy way to fix them, but since i'd painted the tail, it makes it very hard to do without repainting. as for glassing, i'd love to do it, i NEED the extra strength. but, i just dont see how anyone could glass lighter than i airbrushed mine, so its hard to believe his wont be too heavy.
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Old Oct 06, 2004, 06:41 AM
Loose Cannon
Wind Slave's Avatar
Deer Park, New York, United States
Joined Mar 2004
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Successful Maiden

Well I took my glassed Fokker to the field this AM with an AUW of 12.5 oz. She flew with more power and authority than the Pico Tiger Moth that she replaced althought she wasnít as fast as I had hoped. I was using a GWS 1047 prop, Iíll give a 9X7 a shot next time. I really wanted to use my smaller Lipos <would have been 10.5 oz AUW> but I couldnít achieve CG without adding a bunch of dead weight. That being the case I opted to just stuff in a 2sp1500 and leave the hatch cover off. Just had enough time to ROG, trim her out, perform ďthe dive testĒ, and run a couple of circuits around the field. A successful Dawn Patrol.

Catkicker, change the tip in your airbrush.
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