J&H Firefeather build

[Charles_McG]

I re-drilled the wing fastener hole.


Then I spent some time shaping the fuselage. I rounded all the corners and did some tapering on the nose.
I shaped the sides more - they are thicker and softer than the deck. But I also worked a slight bevel on top and bottom decks - about 1/4" by nil.
The tail almost, but not quite got round.
Since the next step if fiberglassing the whole thing, I filled in the various tab slots with CWF and sanded back down.


You can see that the wing screw is too long. I've got a dremel - I can fix than.

I think it's pear eau de vie for tonight.

 

[Charles_McG]

Joshua recommends fiberglassing the body.

I did a weight check before I started - 23g.

Since nobody screamed in horror at my use of Super 77 on the fiberglass, and Joshua himself suggests adding a little more if the tackiness is gone, I went back to my previously stabilized fiberglass on parchment paper.

I did the side first, tracing out the shape with the body itself, adding a 1/8-1/4" margin to wrap around the top and bottom corner.
I smoothed it out - the tackiness works in your favor here. Where it didn't want to lay flat, I nicked it with the hobby knife and laid down one side smooth and the other over top of it. I spent some time to work out any bubbles/wrinkles - but it went on easily.


Then I applied the Super Gold CA, first the nose, then the top and bottom edges, from front to back - then filled in the side wall from front to back. I'd put down an inch or so line, then work it in with a [gloved] finger. when there was enough, it developed a certain greasy feel to it. Then I 'd move on, overlapping a little to keep that greasy feeling. When I had a whole side, I'd hit it with accelerator spray from a distance.

Empennage, wrapping a little around. I worked from the boom forward here.


With both sides done, I covered the top deck. This time I trimmed it really close to the glue seem - a little overlap, but not over the curve.


The bottom deck I did as two pieces to conserve fiberglass - though there was plenty included.

 

[Charles_McG]

So, having covered the whole fuselage in fiberglass and Super Gold CA, I still didn't like how it sounded when I tapped it. Kinda dull, and while the CA was hard this time, but it didn't feel like the hard shell i wanted. I went back over the whole thing with thin CA, back to front this time. I'd put on a couple of drops, and smooth it down - angling it to the light so I could see where it stopped being glossy. Then start from theere with some more drops and keep going. With the right light, I could really see how it was spreading out and filling in. There was a certain slick feel to it, also.

No need for accelerator - it set fast.

Then some sanding to make it even smoother.

Now when I give it a finger tap, it sounds like a nice hard plastic surface.

Final weight: 25g

 

[Charles_McG]

For some strange reason, now is the time to put the throwing blade in the wingtip.


Then on to the motor mount. I'm building this for reloads. If I was building for C6-0 with a vent port, then I think it would need more tweaks than Joshua presents here. He mentions later a spacer - but I think a spacer would need a longer engine hook, too. Anyway, I think I'm good.

Stack and insert forward plug. Notch and place engine hook. Put a little fiberglass over it. Then mount in the fuselage, tipped aft end toward empennage, and the end -just- past the cutout. You can see that I added a ring left over from an estes kit to make the hook tighter. I also mounted it hook up, rather than hook to the side and letting the frame limit the hook. Fillet the inside.


And launch lug - opposite to the vertical stabilizer.

 

[Charles_McG]

Now I build a nosecone on the same platform that could mount an electric motor.
This gave me fidgets, I will admit. I watch the video multiple times at 1/4 speed and paused frequently to figure out what's going on - and finally decided I was over thinking it. More later.

Here's the base. parts. and stacked, making sure the holes align.


Then the plate. It took me a while to determine this was the correct orientation - hole partly covered, small gap at bottom. And the other plate.


I wanted a pointier nose than Joshua did. So I stacked 2 1/4" balsa pieces. I also didn't know I was supposed to save the scrap - so I had to make a run to The Store That Shall Not Be Named to get more. I put the grain horizontal.



I marked the midpoint to help with the shaping.




Now, what really gave me trouble is that I was paying attention to the holes on the insert, and the holes on the sides of the front of the fuselage, thinking the something (screw/pin) would go in to hold the nose. I watched over and over, and became convinced the Josha mounted the nose former upside down, and that was leading him to mount the nose insert upside down (to get a better flush fit with the fuselage). I watched him, time and again, rotate it over so that the holes -didn't- line up. I built the thing part way and tried running pushrod thru, just to verify. The holes don't actually line up, even if you try. They are a red herring. I flipped it back the way Joshua does and carried on.

 

[Charles_McG]

Finish shaping, and fiberglass as before.



Joshua says there are enough parts to make two of these - one for an electric motor. He's wrong - there are only 2 of the 1/32" ply sides - not 4.
He also skips -entirely- how to fasten the nose securely. I'm thinking long, tiny screws, but I don't know where I'm going to get them.

The next step is to mount servos. I spent the day trying to connect my Spektrum DXe to my laptop so I can update the programming to something suitable for a sailplane. I failed. Customer Service suggested I upgrade to something newer. I guess that's what I get for trying to go as cheap as possible about 4 years ago.

At this point, I'm getting me a martini.

 

[Charles_McG]

So, while I was out getting a DX6e to steer this thing with, I picked up some #2 screws for the nosecone.


I'm going to post this next tweek here - it should go back with the tail boom prep. To get full elevator range, you probably have to bevel the end.


So now it's time to mount electronics. The servos are glued together, left and right flaperon, and elevator across the back. I cut off one side of the double sided horn to make them single sided. I ran into several complications:


The servos that I ordered with the kit are a little tall. I'm not even running wires underneath like in the video. To get more clearance, I cut the slot wider - closer to the wing surface. To help level the servos, I added a piece of 3/16" balsa to help wedge it up. Once I had clear motion, I wedged the servo pack in on each side (built up medium and thin pieces of scrap) and added the pushrods. I marked the position to bend - that took two tries on the first one to figure out the radius of the bend. Then bend, cut, and tuck into place.


The elevator gave me fits. This kevlar thread nearly got the better of me. I had to recut the ends several times. I got a little smarter on the other end - I took the horn off to thread it through. After pulling up the elevator to neutral, I wrapped the thread around the horn once, and then around the loosened screw. The correct direction to pull when the screw was tightened back up. I assume Joshua does it this way to allow for re-tensioning.



I haven't glued the servo pack into place yet.

 

[Charles_McG]

I made a bundle of my AR410 receiver and battery pack - a 240mAh 1S battery I have from a micro quad copter. An Estes one, actually. I plan on tucking it forward of the main former, it fits thru and stuffing a packing peanut in to hold it in place.



So here's the build weight, sans motor and not balanced.


I popped in a A8 to simulate an empty casing. Now, Joshua has a motor and prop mounted on his, and he doesn't show it flying with the balsa nose (I think). On video, Joshua showing it balancing just forward of the aileron arm slots. To do that, I found a lead cement anchor that was 15g and wedge it into the nose. So here's the weight loaded and balanced.


Almost there - checking control surface motion.
View attachment IMG_3247.MOV

 

[mikec]

Looking good! I'm guessing that is way more elevator travel than you will ever need, but it's a lot easier to have too much and cut it down with transmitter travel settings than have too little and not be able to get it.

 

[burkefj]

Since the motor is slightly after of the CG location you'll need to re-balance with a loaded motor of course right? Not simulate an empty casing? Youll need at least a C6 which is 24 grams loaded..

 

[Charles_McG]

Since the motor is slightly after of the CG location you'll need to re-balance with a loaded motor of course right? Not simulate an empty casing? Youll need at least a C6 which is 24 grams loaded..

I'm anticipating a 18mm RC casing and a supply of Cs and Ds in my Christmas stocking, so I'll be able to get a better idea after that.

My thought was to balance with an estimate of the burned out weight - for the glide portion, rather than the boost portion. The boost portion is mostly vertical, anyway.

 

[burkefj]

I'm anticipating a 18mm RC casing and a supply of Cs and Ds in my Christmas stocking, so I'll be able to get a better idea after that.

My thought was to balance with an estimate of the burned out weight - for the glide portion, rather than the boost portion. The boost portion is mostly vertical, anyway.

Launch is the most tail heavy you will be, it can still be pitchy if it is tail heavy on launch. Just don't want you to underestimate your nose weight required. A loaded D2.3 with a plugged closure will be close to 29 grams.

 

[Charles_McG]

Launch is the most tail heavy you will be, it can still be pitchy if it is tail heavy on launch. Just don't want you to underestimate your nose weight required. A loaded D2.3 with a plugged closure will be close to 29 grams.

I take it that it's better to be nose heavy than tail heavy - always?

 

[burkefj]

I take it that it's better to be nose heavy than tail heavy - always?

Always, a nose heavy model flies poorly, a tail heavy model flies once.

 

[Charles_McG]

Always, a nose heavy model flies poorly, a tail heavy model flies once.

QSL.

Do you have any comment on the weight I’m coming up with?

 

[burkefj]

QSL.

Do you have any comment on the weight I’m coming up with?

He doesn't ever really spec a rtf rocket powered version, but you are showing 142 with an empty casing, so maybe 11-12 more for propellent gives 154 or so rtf depending on whether you paint the pod or not. 5.4 ounces is pretty reasonable for the D2.3T, anywhere in the 5-5.7 range will give a decent boost altitude and this design is very efficient as compared to my flat plate sport flyers so it should be good, I don't know how much flight time you would get on a C6(fast boost) or C3.4T personally I wouldn't bother with those relative to cost and just go for the D2.3

 

[Paul Howard]

As an RC Glider Guy watching this, this is one of the coolest things I've seen on TRF!!!

 

[Charles_McG]

While organizing the basement yesterday (a big project on the holiday break Honey-Do List), I found that I actually had the 18mm casing and D2s in hand. The stocking must contain the 24mm hardware for my next project. One coming from a certain entity with the initials F.B. - and I don't mean Facebook.

So, I can revisit balancing with the heavy motor in place. Or at least, I could if Joshua actually understood motor and motor clips when he designed the kit. Maybe he does now - I don't know. This gave me fidgets for a while.


The problem is that he's using a solid motor block, while the reloadable motors - that he really recommends in the videos - are meant to fit against a ring, with the plug/charge+delay well poking through. The upshot is the hook is in the wrong place.

I made me grumpy - but the fix turned out to be straightforward. Carefully dig out the forward end of the hook, reposition, cut a new slot. Fiberglass back over.

 

[Charles_McG]

I’m using the lead casing of cement anchors for nose weight.

I take the threads out, and they just tuck into the nose width-wise. I haven’t glue them in yet (one to the top deck, one to the bottom. Rolled all the way forward and lightly wedged into the sides) they add about 23g and put the balance with an unburnt D2.3 -just- in front of the aileron slots.


That gives me a little margin for some paint, per Frank’s guidance above.

While I wait for painting weather, I might try pounding one of the anchors full of spent pellets to see if I can get the weight into a smaller volume.

 

[burkefj]

I hate frustrating things like the motor hook issue, you could have just used a long drill to drill out the motor block to clear the 3/8" nubbin on the end of the plugged casing closure if anyone else reads this and needs a fix...For these reloadable motors you don't even need a hook or block as the rear closure will keep it from moving forward and there is no ejection to make it come out, you just need to make sure that it doesn't fall out after boost, a bit of masking tape does the trick. Looks like it's almost ready!

 

[Charles_McG]

And painted. I have a boy at UW Platteville - so that’s the inspiration.

 

[aerostadt]

Looks gorgeous! To me the build looks like a major undertaking. I love the way Josh throws this thing into the air like a frisbee in his video. Is the throwing pin suppose to come out for rocket flying?

 

[Charles_McG]

Looks gorgeous! To me the build looks like a major undertaking. I love the way Josh throws this thing into the air like a frisbee in his video. Is the throwing pin suppose to come out for rocket flying?

It's more involved than most rocket kits - but wasn't really that bad. I suppose I should reserve judgement until I see how it flies

I hope the throwing blade isn't supposed to come out - it's glued in pretty well.

 

[Aeronerd]

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