DTF Vought XF5U "Flying Flapjack" - Page 3 - RC Groups
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Dec 30, 2017, 10:44 AM
Kimbers Keeper.
BHOFM's Avatar
I am working up a set of plans for a very simple, profile type version. I will start a new thread
when I get to that point.

On the yaw problem, have you tested the motors for equal thrust? You are using CRP's?

I have a set of props for mine. And I am just doing a delta tail setup, no rudders. Increase
the rudders a bit.

I may do a version of their tethered model.
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Dec 30, 2017, 12:52 PM
Registered User
localfiend's Avatar
Quote:
Originally Posted by JabiruAbe
Again I love the looks of this. I probably missed it, but its just props and not edf's, yes? (Userofmuchtape@glue on FT)
Yes, just props. Those 3D printed air intakes look like edfs though.


Quote:
Originally Posted by BHOFM
I am working up a set of plans for a very simple, profile type version. I will start a new thread
when I get to that point.

On the yaw problem, have you tested the motors for equal thrust? You are using CRP's?

I have a set of props for mine. And I am just doing a delta tail setup, no rudders. Increase
the rudders a bit.

I may do a version of their tethered model.
Didn't check for equal thrust, not exactly sure how I would do that, but things have to be similar for it to fly without inducing yaw. These are just cheapo 10x4.7 SF plastic props I've used on other twin planes. ESC's are calibrated.

May have to go down a size for the next flight. Don't think I have any more 10".
Dec 30, 2017, 05:34 PM
Kimbers Keeper.
BHOFM's Avatar
First thing is to check the wattage of the systems. Amp's need to be within a couple ten'ths.

Digital fish scales work for checking actual thrust. hook on the tail wheel, stay clear of the front.
Dec 30, 2017, 08:09 PM
Registered User
localfiend's Avatar
Quote:
Originally Posted by BHOFM
First thing is to check the wattage of the systems. Amp's need to be within a couple ten'ths.

Digital fish scales work for checking actual thrust. hook on the tail wheel, stay clear of the front.
May be worth testing out later. I need a good digital fish scale anyway.

Adjusting the size of the rear control surfaces made all the difference. Moved the CG back up to my first guess and the thing flew great, although, I had an awful lot of control throw at the start. Jumps right into the air at half throttle lol.

XF5U "Flying Flapjack" Success 12.30.17 (4 min 27 sec)


Needed a bit of up trim, about 8 degrees. Dunno if it needs reflex like a wing, but it flew nicely setup that way. Might be able to get rid of some of that by moving CG back a hair, but this is a nice safe setting. I think that like a nutball, the CG range is pretty large. The previous flight had the CG back a full extra inch from what it was here.

Other than that, I'm pretty happy with how it went. Had to land kind of abruptly as someone pulled up, but my soft welding wire landing gear did it's job and folded. Probably woulda just bounced a bit with proper wire. Oh well.
Dec 30, 2017, 08:54 PM
Kimbers Keeper.
BHOFM's Avatar
Where is the CG? on a pic would help.

BTW, I am building the V-173. Going to print the patterns in a few minutes and start taping!

I think my design will minimize yaw.

Plane looks great. Get some wire and fix that problem!!
Dec 30, 2017, 09:05 PM
Registered User
localfiend's Avatar
Quote:
Originally Posted by BHOFM
Where is the CG? on a pic would help.

BTW, I am building the V-173. Going to print the patterns in a few minutes and start taping!

I think my design will minimize yaw.

Plane looks great. Get some wire and fix that problem!!
CG ended up being 5.25" back from the leading edge of the wing. Roughly where the red line is in the attached picture.

I may drive to the hobby store tomorrow and see if they have and hardened wire. I really like the soft stuff for prototypes, as it just folds in a crash without destroying the plane, but once it's proven, proper gear is good.

Might come up with 3D printed scale retracts for this. Gonna need some small servos for the doors, and a bigger receiver though.
Dec 30, 2017, 09:06 PM
Multirotor Enthusiast
Blacky's Boy's Avatar

Nicely done!


Well done! The guys over at Flite Test should do an episode on this plane!

It has it all. Nicely detailed build without being too overwhelming and a tone of cool features. Plus, it's DIFFERENT. It's not the same thing all over again.
Dec 30, 2017, 09:17 PM
Registered User
localfiend's Avatar
Quote:
Originally Posted by Blacky's Boy
Well done! The guys over at Flite Test should do an episode on this plane!

It has it all. Nicely detailed build without being too overwhelming and a tone of cool features. Plus, it's DIFFERENT. It's not the same thing all over again.
Thanks. Was trying to do something new, but balanced for the build competition. Wanted something that would look good, but could be built without a stupid amount of time invested. That said, it does take me a couple long evenings to build one, and a normal FT plane is more like one.

I want to make a bigger version and glass it. Have a couple big motors with no home and I need to try something other than pure foamboard at least once.
Dec 31, 2017, 01:14 AM
Registered User
localfiend's Avatar
And now for more of the build log....


Grab the main cockpit piece

REF75


Remove paper, bevel, and pre-bend as shown.

REF76


Either cut off both end tabs and glue as I did here, or only cut of one tab, remove the foam from the other side, and use the remaining paper flap to help glue things together flight test style. I like to put tabs on both sides of rings where possible, as it helps you to get the proper bend at the tips of your curve.

REF77


Glue the back half like so:

REF78


Here's what it should look like. Don't fit it up to the plane yet. If you try now, the piece will likely tear.

REF79


Grab the next cockpit piece.

REF80


Remove paper and pre-bend.

REF81


Start gluing it up to the main section like this. I like to go a little bit at a time, only using enough glue that it covers all the foam area without spilling out and over the paper. If you have some extra glue no big deal, just wipe it off with your finger after it cools slightly, or more quickly with a piece of scrap foam.

REF82


Continue like this all the way around.

REF83


Grab the next cockpit piece, remove paper, and prebend.

REF84


Cut off the tabs like before, or do the alternate and glue together. After gluing you'll see that the foam bulges out a little bit. For the cleanest fit, I like to shave that off.

REF85


You don't have to remove much.

REF86


Start gluing it in place the same way you did with the other section.

REF87


All glued up.

REF88


Grab the nose circle piece, and remove the outer ring of foam. To make it as clean as possible, I like to hold it against the table, and quickly slice through the paper and flick off the small pieces.

REF89


Glue it into place on the nose. I like to add glue, set the nose piece on the table, and slide the rest of the assembly onto it. Makes it easy to make things straight and clean.

REF90


Next grab the back cockpit section, remove paper, bevel, and pre bend.

REF91


Glue into place. I generally do this in sections just like the other cockpit pieces.

REF92


Now you can go ahead and do a test fit. Check things out, then set it aside. It'l be easier to work on the plane if we wait to glue it in place.

REF93


Time for the intake covers.

REF94


Remove paper, bevel, and pre-bend.

REF95


Then you can start gluing it together. The trick here is to use as little glue as possible, don't let the nozzle of the glue gun touch the foam, and hold the pieces until the glue dries completely. It's not hard, it's just all about patience. Keep in mind that you can add more glue to the back side after you glue up a joint, so it's not a problem to go light for the first pass.

REF96


Here you can see about how much glue I use. You can squirt on a little more and squish it down along the seam.

REF97


Alternate side to side and work your way forward.

REF98


All done. Just 3 more to go.

REF99


Once you finish all 4, you can glue on the back piece. Remove paper, bevel, prebend like usual.

REF100


Glue into place. I like to do one half at a time.

REF101


Go ahead and do a test fitup if you like. Helps to make sure you have enough bend for it to fit cleanly before gluing.

REF102


Before stuff gets glued on however, do the intake tubes. Remove paper and pre-bend.

REF103


Like other circles, either cut off both tabs and glue, or do it FT style with a tab on one side.

REF104



Grab an outer ring and remove the paper from one side.

REF105


Glue it onto the angled section of the intake tube. The inner diameters should match up.

REF106


Glue the intake tube and ring into place like so. Before gluing I like to smooth the exposed foam with a bit of sand paper.

REF107


Now you can glue it into place. I like to glue it all in one go. It's easiest if you take your time and make sure all of your bends are close. You can also do it in sections. Glue the bit by the intake ring first, then carefully add glue to the rest.

You can cleanly progressively add glue to something like this by taking a piece of scrap paper, adding a drop of glue to it, then sliding it under the part where you want the glue to go. Push down on the part and pull out the paper. Tada lol.

Make note of the alignment marks in picture 109.

REF108


Here's the alignment marks on the parts. Should line up with the seam on the outer skin.

REF109


Go ahead and glue up the top of both sides. We'll save the bottoms for later.

REF110


Now the wingtips. You could just laminate layers of foam, glue them to the wingtips, and sand to the proper curve. But this part really isn't that bad if you've already made the cockpit and the air intakes.

Like usual, remove the paper, and bevel.

REF111


You'll want to pre-bend as well. You can see I've glued one section in the back. Do it just the same as the intake covers, alternating sides starting from the back.

REF112


Should look like this when done:

REF113


You'll probably need to bend it some more. Don't be afraid to squish it a little.

REF114
Dec 31, 2017, 10:45 AM
Registered User
newcomer's Avatar
nice work. good tutorial!
david
Dec 31, 2017, 01:19 PM
Registered User
localfiend's Avatar
Quote:
Originally Posted by newcomer
nice work. good tutorial!
david
Thanks man, hopefully this will be enough pictures lol.

Dan worked late last night and got the plans all ready to go.

These are as complete as the plane is now and has all the parts. A new version of them will likely be coming out that details stuff like all my bevels, part orientation, paper removal, cavities etc, but in the meantime, the pictures from the build log should do just as well or better.

All-In-One

Full-Size

Tiled A-Size Sheets

Tiled B-Size Sheets

I've also attached a picture that shows how I lay out the parts on 20x30" dollar tree foam sheets for my CNC machine so that you can see proper orientation. If you cut out some parts against the grain, bending them won't be as easy.
Jan 01, 2018, 12:15 AM
Registered User
localfiend's Avatar
And here's the rest of the build log.


You'll want it to have enough bend that it can be pressed flat on a table like so:

REF115


Glue up the top side of the wingtip. You can do this in sections if you're very careful, or if you use the piece of paper with glue on it trick.

REF116


Next, do the same thing to the bottom. If you need, you can squirt a little bit of extra glue inside now and smooth it down with a BBQ skewer to make sure the top half is well glued.

REF117


Grab the motor pylon tube thing, and do the usual. Remove paper, bevel, and pre bend like shown.

REF118


And also like usual, cut off both tabs and glue, or do it FT style with the flap.

REF119


The tube simply slides on. Take your time here, make sure it fits nicely, is round, and is straight with the paint stick.

REF120


If you're using my 3D printed firewall, you don't need these circle pieces. I put 8 of them on the plans if you're going to use a simple firewall, push and glue a few of them into place. I only stuck one on the entrance here, cause I didn't want pieces of foam stuck in there getting in the way of the 3D printed firewall.

You can use a FT firewall, just trim to to match the circle. It's 1.75" diameter. A razorblade will do the trick if you're careful, then you can clean up with sandpaper.

REF121


Here's the 2 piece 3D Printed firewall bits. These are sized to the Power Pack C motor (GT2215/09), but the bolt pattern fits pretty much all motors of a similar size.

The pieces with the bolt holes for the motors are different. There's a 90degree angle difference between the two of them so that you can get motor wire coming out at your preferred angle. I like my motor wires to be on the bottom pointing inwards toward the plane.

REF122


Here's the motor bolted up.

REF123


That piece slides into the main base and can be secured by a spare motor screw on each side. You could also CA these parts together.

REF124


The part should just slip into the tube and over the paint stick. I've chamfered the 3D parts pretty well, but I suppose additional fitting could be needed. The 3D printed part is pretty beefy, and you can remove a bunch of material with something like a drill before it loses strength.

Make sure the part slides into place easily, and check to make sure you have it straight before using hot glue to fix it in place. I like to attach a prop to help me eyeball straightness.

REF125


Now were at the point of just sticking all the other bits onto the plane. You can do the rudders now, it would also be a good time to glue on the bottom air intakes. I like to get an old pillow, put it in a trash bag, and use it as a plane rest. This thing can be awkward to work on at this stage, and the pillow really helps.

Like usual, remove paper and bevel. The rudders go together just like the tailevator sections. I didn't choose to cut out funtional rudders on this version, but the lines are included on the plans if you would like.

REF126


Add glue just like the tailevator and fold over.

REF127


Go ahead and cut out the rest of the foam where the rudders go. If your lines don't match up perfectly, no big deal. Just stick the rudder in place and trace around it. I don't think the angles here matter too much as long as they're not extreme and both sides match.

REF128


I didn't take any pictures to show gluing the rudders in place, but it's pretty simple. I put a slight outward tilt on them. Once again, I don't think this angle is critical. Just make both sides the same.

REF129


Take the finished cockpit section and glue it in place now. The point on the top, and the curve on the bottom match up to the center seam. Pretty straight forward.

REF130


If you haven't already, go ahead and glue in the 3D printed cosmetic pieces if desired. I'll include a picture you can print out to have fake intakes if you desire. Or you can fab something up yourself.

The nose piece can be made from laminated foam sections sanded to shape. Take some scrap foam, remove paper from both sides, and build up several layers of it. It's really quite easy to sand if you keep your hot glue in the center area and away from the edges you use to sand.

For painting exposed foam, a layer of elmers glue does well to make a surface layer to separate the foam from paint solvents. You can also use just about any form of wood putty etc...

REF131


The canopy can be done a couple different ways. You can print it on paper and use as is, print it directly onto a printable overhead transparency, or do a combination of the two.

If you want to do the combo, print out on paper, and cut out the window areas.

REF132


Use spray adhesive on the back side of the paper, let it tack up a bit, then carefully lay on top of an overhead transparency or other form of flexible plastic sheet.

REF133


Once the glue has dried (give it at least 5 minutes), cut off the excess.

You can also see I've added a slight crease to the back point to help it along as we glue it up.

REF134


Glue one tab at a time. It only takes a small drop of hot glue. I like to make sure the tabs are on the back side, it looks cleaner. Laser overhead transparencies work best. They're designed to have hot toner stick to them, so hot glue bonds quite well with no prep. Watch the stringing from the hot glue though, the strings like to really stick, and no one likes a dirty windshield.

REF135


Do one complete side, then the other.

REF136


Then glue it onto the cockpit. I like to only add glue in three places. A couple drops right at the back point, and then a couple drops on each side where the overlap is the thickest. This way, it will stay attached in flight, but generally pops right off if you "land" in a tree or something. It's easy to re-attach.

REF137


I'd imagine if you're building this plane, you probably have a preferred servo horn and pushrod arrangement. I like this method. Simple, and it just works. I've included gauges for Reflex, as well as control throws for both elevator and aileron control. Best setup method for this plane is quad elevon. Essentially, every control surface should do both elevator, and aileron.

REF138


Didn't have a lot of time to get too fancy with landing gear, but I do have a 3D printable tailwheel that can be servo controlled, and some 3D printable mounts that take a 2-3mm ish landing gear wire. I used the same mounts to attach both skis and wheels. I'll upload files for the skis as well. The tailwheel is probably only needed if you want to pretty up the plane, or if you don't use any differential thrust. With diff thrust you could probably use a brick for a rear skid and still turn lol.

REF139

REF140


And that's pretty much. I'll be happy to answer any build questions you might have. More refinements may come to this guide in the future, but I think I covered pretty much most of it.
Jan 01, 2018, 01:26 AM
Registered User
localfiend's Avatar
Optional 3D Printable stuff:

The bulk of the 3D printable parts are here:

https://www.thingiverse.com/thing:2740856

That link includes the nosecone, firewall pieces, landing gear mounts and skis.

The air intakes created by Dan can be found here:

https://drive.google.com/file/d/1-q_...ew?usp=sharing

And the steerable tailwheel assembly can be found here:

https://www.thingiverse.com/thing:2740873
Jan 01, 2018, 10:12 AM
Ken's CAD Models
dz1sfb's Avatar
This baby would really be complete with a set of retracts!

Ken
Latest blog entry: Ken's CAD Models new web site
Jan 01, 2018, 12:09 PM
Registered User
localfiend's Avatar
Quote:
Originally Posted by dz1sfb
This baby would really be complete with a set of retracts!

Ken
Got a set of hobbyking retracts that should fit. Think I may design scale looking 3d printable stuff though. Need to get another receiver with more channels first.


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