Ft viggen group build!

[The Hangar]

So no ftfb at the hobby shop... oh well. Dtfb it will be. As far as landing gear does, I didn’t pick any up since I haven’t built the plane yet ind I don’t know what tire size it needs. Also, I usually fly off grass so landing gear would be pretty useless.

 

[FoamyDM]

Seriously I do not think it would be as pleasant to fly if it was smaller as the wing span is somewhat minimalist as it is. With the 64 it flies quite well but it just seems to lack a bit of thrust on launch and when throwing it hard into the turns. Basically it doesn't accelerate as good as many would expect but no doubt it flies OK, With a 12 blade 70mm it can really go and can almost hover at high alpha. You would be better using the pusher setup rather than attempt to scale it down.

Just another thing the build can be a little tight at times using the full size build if smaller it may be a lot more difficult to get all of the folds done accurately and properly,

It is just a pity that the plans are not in the modern or newer format!

Just my opinion!

Have fun!

I've felt the same way about format. I may spend a moment to do that. If I do I will post in the resources and put a notice here and the FT Viggen thread. And I have to rebuild mine, so I may scale it just to see if the 64mm performs better.
Or try a few lightening techniques that may help.

 

[FoamyDM]

The hatch was first cut into on of my builds for another club member. He specified a 64mm build and after flying it he wanted to upgrade it to a 70mm EDF. He just cut a rectangular hole directly below where the EDF unit was fitted and started hacking at the internals. He initially glued the cut out piece back in but over time he replaced the "hatch" with a piece of ply which had a rectangular cut out in it in front of the EDF to allow more air in. He just holds the hatch in place with some reinforced packing tape!

At the moment I am building another Viggen for a different club member and he wants to have a slide in/out EDF pod to ease changes and the like. The only real issue in doing that is the access to the wiring and so I am slowly plodding through the build and his requirements! If I manage it I will post the method/pod.

One additional change was the use of a stiff plastic to make the thrust tube because the card was a little flexible and actually ballooned at full thrust causing a loss of thrust. The more rigid tube made a significant difference!

Have fun!

I'm just seeing all this... Did you tape the full length of the tube when it was Card stock? I don't remember having the same issue.

 

[Hai-Lee]

I'm just seeing all this... Did you tape the full length of the tube when it was Card stock? I don't remember having the same issue.

The tube was just bare card and I suspect that the tube got a little damp, (heavy morning dew here). If you land with the EDF turning it sucks up all sorts of things, (including water on the grass). It can look like a big explosion if you do a low, high speed, pass and tap the ground because of the water it throws out of the rear.

I am supplying a different material for a thrust tube this time. A PET bottle of suitable length and diameter. Much more rigid, waterproof, cheap, and sadly a little heavier!

Photos later today!

Have fun!

 

[Headbang]

The tube was just bare card and I suspect that the tube got a little damp, (heavy morning dew here). If you land with the EDF turning it sucks up all sorts of things, (including water on the grass). It can look like a big explosion if you do a low, high speed, pass and tap the ground because of the water it throws out of the rear.

I am supplying a different material for a thrust tube this time. A PET bottle of suitable length and diameter. Much more rigid, waterproof, cheap, and sadly a little heavier!

Photos later today!

Have fun!

Good point. My x-29 was full of 2lb of snow and ice after maiden flights.
Just minwaxed the inside of the viggen fuselage forward of the edf.

 

[Matthew Sanders]

Earlier you were talking about how 64mm EDFs were not as powerful on take off. What battery was being used

 

[Hai-Lee]

Earlier you were talking about how 64mm EDFs were not as powerful on take off. What battery was being used

Due to the weight of the local FB he was using a 3300 4S. When he upgraded to the 70mm 12 blade on 4S the current really went up but then so did the performance.

If you are unable to source the lighter DTFB/FTFB I would avoid the cheaper 64mm EDF units, (5 blade).

Have fun!

 

[Matthew Sanders]

Earlier you were talking about how 64mm EDFs were not as powerful on take off. What battery was being used

Due to the weight of the local FB he was using a 3300 4S. When he upgraded to the 70mm 12 blade on 4S the current really went up but then so did the performance.

If you are unable to source the lighter DTFB/FTFB I would avoid the cheaper 64mm EDF units, (5 blade).

Have fun!

Would an 11 blade 64mm on light DTFB work? I'm so new to EDF s that I don't know what difference the amount of blades make! Also, my planned ESC is 60 amps. Would a 2200 3s work?

 

[Hai-Lee]

Would an 11 blade 64mm on light DTFB work? I'm so new to EDF s that I don't know what difference the amount of blades make! Also, my planned ESC is 60 amps. Would a 2200 3s work?

The FT kit version mentioned earlier, (the one that caught fire), was initially flown on a 64mm EDF and a 3S battery. It flew well enough. I am not sure which fan he used but i know it was not a 5 blade unit.

The higher the number of blades the less of the air is free to slip backwards, (between blades - High pressure on one blade to the low pressure on the next blade), and the more air it pushes. There is a limit though where the blade thickness starts to impede the through airflow. KV is what you need! KV also means larger ESC and current draw!

Have fun!

 

[The Hangar]

Would an 11 blade 64mm on light DTFB work? I'm so new to EDF s that I don't know what difference the amount of blades make! Also, my planned ESC is 60 amps. Would a 2200 3s work?

Check the specks on the edf and see what the amp draw is for 3s

 

[The Hangar]

@Matthew Sanders are you joining in on the build?

 

[Matthew Sanders]

I'll post a link to it.
https://www.amazon.com/dp/B07C3Z2JCQ/?tag=lstir-20

Yes, although I'll be a little bit late. Cutting out foam when Scratch building is a long process

 

[The Hangar]

I'll post a link to it.
https://www.amazon.com/dp/B07C3Z2JCQ/?tag=lstir-20

Yes, although I'll be a little bit late. Cutting out foam when Scratch building is a long process

60 amp will be plenty good. I’m cutting out the foam too😂. I’m trying a new technique for this build - using a sewing machine with out thread to cut the pieces out - it works really well!

 

[Matthew Sanders]

60 amp will be plenty good. I’m cutting out the foam too😂. I’m trying a new technique for this build - using a sewing machine with out thread to cut the pieces out - it works really well!

A sewing machine? What will FT scratch builders think of next? That's a brilliant idea! I'm glad I'm done cutting out my X-29. Still waiting for the extentions to come for that, but I have everything for a Viggen, minus a cut out airframe and an EDF. That's why I can handle 2 projects at once.

 

[Headbang]

Would an 11 blade 64mm on light DTFB work? I'm so new to EDF s that I don't know what difference the amount of blades make! Also, my planned ESC is 60 amps. Would a 2200 3s work?

It all comes down to thrust, look at the rated thrust for the edf, assume at least 10% error. You are looking for a 1 to 1 wieght to thrust. So if a 64 11 blade is rated at 900g of thrust, figure it will produce 800 in reality, meaning your all up wieght with battery needs to be 800g or less.

 

[Hai-Lee]

Yet another modification. This one is to try and stop the ailerons from lifting off of the paper and to keep them stronger for longer.

The alternating bevel cut into the top surface of the wing.



Getting close to being finished. Just the powerpod, vertical fin, and the paint job to go!



More later when the painting is finished. The delay in the powerpod posting is so that I can show it fitted into place.

Have fun!

 

[Matthew Sanders]

I'm going with a swappable Viggen. I really wanted to do an EDF but it's not working out. I can't find a good 64 or 70 mm fan at ANY of the hobby stores around where I live. Off to Amazon (maybe). Oh well. I'm getting a speed build kit after I most likely crash this one. @Hai-Lee you know sometimes when the edge of a control surface rubs the static part of the wing or stabilizer, how are you keeping the stepped bevel from binding?
- A curious plane maker!

 

[Hai-Lee]

I'm going with a swappable Viggen. I really wanted to do an EDF but it's not working out. I can't find a good 64 or 70 mm fan at ANY of the hobby stores around where I live. Off to Amazon (maybe). Oh well. I'm getting a speed build kit after I most likely crash this one. @Hai-Lee you know sometimes when the edge of a control surface rubs the static part of the wing or stabilizer, how are you keeping the stepped bevel from binding?
- A curious plane maker!

As for the fuselage I give it a little trimming, (a wipe of sandpaper).

With the apparent steps in the hinge line with the bevel going from the LE to the TE. I just flex the hinge line to maximum deflection in both directions and that is all that is required. The foam compresses sideways just a tad, (way, way less than a mm), and then the whole hinge line is free!

Used the same hinge on many models now, (Especially those with very long hinge lines), and never had a problem, (I even used 3.7 gram servos for most of them),

Have fun!

 

[Matthew Sanders]

One more question: do you then not use the hot glue in the seam trick?

 

[Hai-Lee]

One more question: do you then not use the hot glue in the seam trick?

Definitely not!!! My hot glue skills are not that good and neither is my eyesight! (I must be getting old).

I use white woodworking glue, (PVA), and wipe in on with my fingers making sure I get it in to every exposed nook and cranny. When it is dry it is quite hard, holds the edge firmly and is easily painted with almost anything!.

Have fun!