FT 3D - Scratch Build

[sconnie]

128% FT3D

I too made a couple regular sized FT3Ds and found them to be heavy and not really very satisfying from a 3D standpoint.

I've built a few FT3Ds at 28% bigger. Mine have about a 41.5" wingspan. Totally different flying plane than original with lots of glide, super low stall speed, hoverable, KE, harriers, snap rolls, really stable and will handle some wind too (and I'm no great pilot either!). I use an emax 2218/9 and an APC 11x5.5 and I've been using the HXT900 servos with no problem. 3D is better with an 1800 or 1550, but it will carry a 2200 just fine. I put 1x3mm cf strips in the elevator and rudder because as you scale it up, those things get floppy - I cut channels for them and put them into the foam, (sorry pics to follow) and glue in with foam safe CA. I remove a lot of paper from the foam. The fuse has the paper left on the outside to facilitate the 90 degree folds, but the wings and other pieces have paper removed from both sides and then I use colored packing tape. Wings have packing tape on outside only and tail pieces have packing tape on both sides for rigidity. I also found it necessary to use small cf tubes to make struts for the horizontal stab as that also starts to flop around as you scale up. Everything is scaled up 28% except the fuse is that same height and width as the original size, just 28% longer. Also, I thought the ailerons were quite wide, so I removed a full 1" from the width after scaling up, but added that back to the wing cord giving the same wing area. I don't use a power pod, I just glue in the ft firewall/motor mount.

AUW comes out to 628g with a 1800 battery.

On the one that I'm building now, I'm reinforcing the edges of the balsa spar with a bigger size of cf strip as I noticed the last one has quite a bit of wing flex. It held up to all sorts of flying and it didn't appear to flex in flight, but I know it was too flexible compared to other planes out there. I will also probably use towerpro MG90S, at least for the rudder and elevator to see if it makes a difference.

As I mentioned, it becomes an absolute blast to fly and even with my meager piloting skills, I get lots of positive comments and curiosity about it at the field.

These don't crash pretty as the fuse area between the wing and motor mount crushes easily and I always have better ideas for building a new one rather than repairing.

Here's a couple of kind of blurry pics of one of my previous builds at 128%. I will post more pics tomorrow....



cheers,
sconnie

 

[sconnie]

Here you can see the spar for the horizontal stab:



Here's the 1x3mm cf strips in the rudder and elev:


I can't tell you what a wide flight envelope this plane has at this size and configuration. It can do snap rolls like my 3DHS Edge 540 and it's easier to land than my E-Flite Apprentice!

At 28% bigger it's a great size as the fuse just barely fits one sheet of dtf and the unfolded wing just fits one sheet as well.

My next one will be a little heavier because of the servos and reinforcement of the spar with extra cf. I'll let you know how it turns out! I'm interested to hear how others have fared with their scaled up FT3Ds!

sconnie

 

[Kurt0326]

I like how you use the cat for scale.

Looking good.

 

[FunTom]

Very nice. Thanks for sharing it.

Whats the easiest way to enlarge the plans in one dimension only?

I am on the fence of building ~125% ft3d, or doing my own design of Extra 330sc. I didnt like normal size ft3d, so I want something bigger. Had much better experience with 120% Spitfire I made, than regular size. So if it works similary for ft3d I might be very happy with that. But trying new design could be fun too and should teach me something. Maybe Ill just remake a fuselage little bit and keep wings of enlarged ft3d..

 

[sconnie]

...

Whats the easiest way to enlarge the plans in one dimension only?

...

I use photoshop for work, so that has been my tool of choice. Maybe not the best, but I know it and have access to it so that's what I've been using.

Sketchup is free and popular and actually does 3D modeling. It looks like it would do the job and once you learn it, allow you to do other stuff as well. You may also want to look at GIMP which is another free one and more of a photoshop replacement as I understand it (not 3D modeling).

Once you know one of these programs, you can make little tweaks to the design as you go.

I have my fourth 128% FT3D almost done. My next one after this will have a longer fuse. I'm using the proportions from the original FT3D and if I compare it to other 3D planes, it's kind of short. Most 3D planes seem to have a 1/1 wingspan/length ratio. I'm counting the tail in the total length, not just length of fuse on paper. The 128% ones that I've been doing come out 2-3 inches short in total length from the 1/1 ratio, so this one will have to span two sheets of foam. I'm hoping this will produce a more stable hover.

I also plan to have tapered ailerons. Even though I reduced the cord on mine, it's still constant from tip to wing root. Most 3D planes have wider ailerons by the root that taper as they go to the wing tip. I've toyed with the idea of putting the aileron servos in the middle of the wing like a more normal plane, but that presents some challenges too.

Finally, I'm getting interested in profile planes and may do a profile version.

Hope others share their experience with the scaled up FT3D!
sconnie

 

[FunTom]

I have never dealt with PDF in photoshop but I'll give it a go. I have model of Extra 330 almost done in SketchUp, so that's probably what I'll build soon. Yea it seemed to me that your plane is too short, wasn't sure if its not only the picture decieving. How did that happen?
Also those wings look huge - probably because fuse is so narrow.

Ailerons - I'm gonna do them as Extra has - in a L shape at the wingtips.

I have 2 profile planes at home, one small on big, haven't done either of them yet, but looking forward to fly them - its great cause they are so light, but problem I have with them is that it's not 'real' airplane, since there is no airfoil and fuselage, its just a board being dragged by propeller but stuff some people can do with them is amazing, nothing beats that manoeuvrability.

 

[Zap brannigan]

by just sizing up in the printer in the "%" sacle in the lower left side of the box and printing in "poster" i have printed and flown the spitfire,blunt nose versawing,and a really nice corsair designed by filkin,that i crashed.
all of them were 200% and fly much better than the original size!
just use yardsticks from ace hardware (1.00)for spar reinforcements and double the thickness for the tail feathers.
good luck!

 

[sconnie]

...

Yea it seemed to me that your plane is too short, wasn't sure if its not only the picture decieving. How did that happen?
Also those wings look huge - probably because fuse is so narrow.

...

As I mentioned, I do think it's too short, but the pic may be kind of deceiving also. The original has a ws of 33" and length of 29.5", so it's pretty short too and I just scaled those dimensions up without changing them. Makes for a maneuverable plane in yaw! KE loop is possible! but like I said, I'll be changing that in the next one.

There are profile planes that are flat foamies, but I'm going for the balsa profile type design but made out of dtf with a flat fuse and big airfoil like the skeeter or mojo.

cheers!
sconnie

 

[Bayboos]

Hey Sconnie, what a wonderful plane! Can I ask for more info about it? Thanks.

 

[sconnie]

Hey Sconnie, what a wonderful plane! Can I ask for more info about it? Thanks.

Just want to be clear, the above pic is not my plane (i wish ), but just an example of one that I want to build out of dollar tree foam, that is, a profile fuse with a thick airfoil. It is someone's balsa version of a plane called the Skeeter 36. It's a classic profile design that's been around for a long time. You can read more about it here: http://www.rcgroups.com/forums/showthread.php?t=509797

sconnie

 

[beradthefish]

Changes

Gents, I've searched extensively for this but came up short: I'm building the speed build ft3d kit. What is the hole on top of the fuselage closer to the prop? I've noticed this and other subtle differences in the build also not addressed in the video. I looked for updated video/instructions but again, found nothing. I'd appreciate any help! *Edit, going to make a big assumption that it's an air vent...

 

[A-wing]

air vent

You are correct. It's an air vent. Make sure your esc goes below that vent and not too far forward so it gets ample cooling. The air exits the triangular opening in the bottom of the tail, so make sure that is open as well.

 

[sconnie]

Here are some pics of my latest FT3D 128%. It has 41.5" wingspan. I just weighed it at 754g with a 1800 battery. So about 26.6 ounces. It's my favorite plane to fly! This one has cf strips reinforcing the wing spar for stiffness. Makes it a lot more efficient. These things get floppy as you scale them up! You can also see the cf spars for the horizontal stab.

I'm going to be working on more variations of this one....

 

[offaxis]

The 130% is a great size if you can keep it under 1000g AUW. I've been flying mine on a 9x6 prop because that's all I have at the moment and its still a blast. My roll rate is not as fast as I was expecting but my control rods could be flexing. I've noticed that my wings are flexing pretty hard when doing maneuvers so I will have to revisit that. I've also stripped a servo in a crash. The Tower Pro 9 grams are not as durable as the hextronik 9g.

 

[sconnie]

Thanks offaxis for sharing your results!

I'm using MG90S servos on this one (my fourth ) and they are great. Digital, metal gear. I was using HXT900 on all of my other ones. They never failed on me, even thru some crashes, but I can feel the MG90S are stronger. I changed the position of the aileron servos to be closer to the control horn to try to avoid flex. Still not sure if rudder and elevator rods are flexing or not. My roll rate is not ballistic either, but I only have the rods on the middle hole of the horns, so I'll be moving them in one notch and it should get better. As it is, I have enough authority to get out of trouble in high alpha which is important as this is my hovering trainer

I've gone thru several different props and am finally on an APC 11x5.5E which seems sweet. The setup pulls 26A when using the emax 2218/9. I'm tempted to try a 12x6E, but I think that would put too much stress on that motor. I can get 8 minutes out of a 1800 and I also use 1550s sometimes. Battery needs to be further fwd since I went to the MG90S.

On this one for wing flex, I used the 1x1/4 balsa spar that they recommend, but it's 24" and both edges are reinforced with cf that is 1/4" wide (not sure how thick) and ca'd to the edges of the spar. And then I use epoxy with this spar setup when installing the wings. Makes quite a big difference.

For a 3D plane, keeping AUW down seems crucial. I strip the paper off of both sides of the wings and tail surfaces and use colored packing tape on the outside. The fuse has paper on the outside, but it's removed from the inside. No pod, I just glue in the firewall. The area between the firewall and wings is weak in a crash, so I'm working on a way to improve that...

No sfgs or vgs are needed for me. This is the size that the FT3D should have been all along! I can't recommend it enough.

 

[sconnie]

Better motor for FT3D

Hi All, just updating on my continuing efforts with the FT3D...

I am sticking with the 128% size, it seems like a sweet spot. On my current one, when I hover, I need to use a lot of right rudder to keep it from drifting left. Not sure what's up with that.

I was using an Emax 2218-9 with an APC 11x5.5 and 30 amp esc and it would pull around 280+ watts on the meter. I'm now using a Super Tigre .10 outrunner - had to go to a 40 amp esc. Excellent motor! http://www3.towerhobbies.com/cgi-bin/WTI0001P?I=LXXGY4&P=8 More zip and I think it even weighs less than the Emax 2218-9. I didn't have a chance to try different props, so I tested it with the same APC 11x5.5. Much easier hovering, but still drifts left a lot. I have right thrust built in, but maybe I need more? Seems to fly straight otherwise, even on full throttle into a loop which it wouldn't do before I put in the amount of right thrust that I have now.

I'm also building another FT3D in about the same wingspan, but with the following changes:
1) Longer fuselage. My last few, the fuse just fit on the 30" dtf board. This one I needed to go across two boards, but not by much. Hoping for more stable hover.... On the original plans, the fuse it pretty short for the wingspan compared to some other 3D planes of this size.
2) Wing cord at the root is the same, but is wider at the tip by about an inch. Again, hoping for a more stable hover.
3) Tapered ailerons - wider at the root and narrower at the tip.
3) Carbon fiber arrow shaft for the spar. This requires modifying how things fit together with the wing. And laminating some 1/16" ply into the fuse for support. Considering gorilla glue for gluing in the spar and wing instead of the epoxy I had been using for that. I'm going to need it to fill in the voids.
4) Thicker foil in the wing and also moved the thickest point back a bit. Thickness won't taper to the tip, but be constant all the way thru.
5) Fuse is reinforced with a second layer of foam from the nose, back past the wing spar insertion point and also just behind the rear of the hatch on the sides where the fuse bends to the tail. I'm liking gorilla glue for laminating dtf. Removing the paper first!
6) In my previous pics, you can see how I use cf strips inlaid in the tail pieces. I'm considering laminating 1/64" ply to a single thickness of dtf with gorrilla glue. This will make for thicker and heavier tail pieces, but I wasn't happy with the flatness of the way that I was doing it before. Not sure if I can get away with tape hinges, but not sure what my other options would be.

With all of the reinforcing, this one will be heavier, but I was doing pretty well in the AUW with my last ones, so I'm hoping to be in the realm of flyability and still be floaty.

I might be crazy, but I'm considering this motor: http://flyairhobbyrc.com/electric-m.../emax-gt-2815-6-brushless-motor-power-10.html
It weighs in at a hefty 117g compared to the 70-80g motors that I've been using. I'm hoping to swing a 12x6 with it.

I'm hoping some of you FT3D fans see this post.

Comments and feedback welcome!

 

[Vince Nash]

My Ft 3d Build from Australia

G'day from Australia
for those people who are interested in my build of the Ft 3d Plane made from Australian foam
Well just to start with AUW is 825grams or 29.10102oz to be exact. yep its heavy with a 1350 rhino lipo
but saying that, it flies really well,for a about 4 minutes of flight time. and If I put a 2200mah it bumps the weight UP
so I didn't fly it.



My FT Spitfire weighs AUW 790g= 27.86643oz NTM Prop Drive Series 35-30 1100kv w =88gs
but flies great with a Zippy 2200mah (7 minutes) I also put a battery canopy on it


Equipment used in this FT 3d build:
NTM Prop Drive Series 28-26A 1200kv / 250w
Turnigy 9 x 4 Gram Servos
TURNIGY Plush 25amp Speed Controller -
1350 Rhino lipo 115grams
OrangeRx transmitter & Receiver
playing around with different props sizes 10x4.7 sf, 10x5 E, 9x6E ,9x4.7 sf


I have upgraded the motor to a NTM Prop Drive Series 35-30 1100kv w =88gs Still has a 4 minute flight time,with the 1350 lipo

I have modified it a bit by adding a battery hatch at the top instead of below,yes the pod is permanent.
because its easier for me and the tail doesn't get damaged when I turn it over all the time.

photos below







Maiden short flight video

There is a lot of stress on the foam, the hot glue broke away from the wings after a few flights

I think the ft planes are great but made for the lighter foam or I should say not as dense
here is a photo of the cross section of 5mm ozzy foam which I bought locally ( Brisbane Mt Gravatt Picture framing)



My first plane was the FT old Fogey its all up weight with pod = Turnigy Bat 1300mah = 578g= 20.38835oz

I have to fly them slow and on a none windy day,
the electronics didn't suit the weight of the plane, I went through a couple of motors and batteries, there's a lot to say about insight

I have learnt a lot about building Rc planes in the past year and 95% is from flitetest
I will look forward to the day when we can get Dollar tree foam in Australia.
but by that time I will have worked out power to weight ratio.

And I will have mastered 3d flying (maybe)

If you have read this little blurb about my FT 3d build Thanks for your time

 

[beradthefish]

Looks great Vince! Would like to see the YouTube video of your maiden but it's private. I finished mine months ago but am still looking for a place to maiden. My membership at my local club expired and I have no plans to renew unfortunately.

 

[sconnie]

Vince, that is awesome work my friend! You are really good. Also, anything with flames on it will win me over every time. You should make your youtube video public, so we can see it! I'm a big fan of the FT3D and I think it has lot of potential for modification like scaling it up. I encourage people to modify the design to fit their dreams!

It's great how flitetest gives us a template to get started and we can modify it and work from there.

If you want to pay shipping from the US, I'll send you as much dollar tree foam as you want! hehe.

I'm working on another scaled up FT3D, so wingspan will be about 41" again with tweaks like longer fuse and larger wing area. I'll post pics of my progress in a couple of days....

Keep building!!!
sconnie

 

[Vince Nash]

G'day from Australia
for those people who are interested in my build of the Ft 3d Plane made from Australian foam
Well just to start with AUW is 825grams or 29.10102oz to be exact. yep its heavy with a 1350 rhino lipo
but saying that, it flies really well,for a about 4 minutes of flight time. and If I put a 2200mah it bumps the weight UP
so I didn't fly it.

View attachment 53393

My FT Spitfire weighs AUW 790g= 27.86643oz NTM Prop Drive Series 35-30 1100kv w =88gs
but flies great with a Zippy 2200mah (7 minutes) I also put a battery canopy on it
View attachment 53372

Equipment used in this FT 3d build:
NTM Prop Drive Series 28-26A 1200kv / 250w
Turnigy 9 x 4 Gram Servos
TURNIGY Plush 25amp Speed Controller -
1350 Rhino lipo 115grams
OrangeRx transmitter & Receiver
playing around with different props sizes 10x4.7 sf, 10x5 E, 9x6E ,9x4.7 sf


I have upgraded the motor to a NTM Prop Drive Series 35-30 1100kv w =88gs Still has a 4 minute flight time,with the 1350 lipo

I have modified it a bit by adding a battery hatch at the top instead of below,yes the pod is permanent.
because its easier for me and the tail doesn't get damaged when I turn it over all the time.

photos below

View attachment 53390

View attachment 53391

View attachment 53392

Maiden short flight video

There is a lot of stress on the foam, the hot glue broke away from the wings after a few flights

I think the ft planes are great but made for the lighter foam or I should say not as dense
here is a photo of the cross section of 5mm ozzy foam which I bought locally ( Brisbane Mt Gravatt Picture framing)

View attachment 53397

My first plane was the FT old Fogey its all up weight with pod = Turnigy Bat 1300mah = 578g= 20.38835oz

I have to fly them slow and on a none windy day,
the electronics didn't suit the weight of the plane, I went through a couple of motors and batteries, there's a lot to say about insight

I have learnt a lot about building Rc planes in the past year and 95% is from flitetest
I will look forward to the day when we can get Dollar tree foam in Australia.
but by that time I will have worked out power to weight ratio.

And I will have mastered 3d flying (maybe)

If you have read this little blurb about my FT 3d build Thanks for your time

The videos are now public

Quick fly and Landing

Since then, I have changed the wing, because of the weight it now is a one piece wing, yes I joined it in the middle
it kept braking away from the fuse.
as you can tell this a band aid fix till I rebuild a new one just to get the bugs out.






as you can see there are a lot of creases in the foam in the fuse, around the front and at the back of the wing.
till next time