J & H Carbonette-19 build thread

[Charles_McG]

After my less than successful Firefeather experience, I decided to try something a little easier (and hopefully slower) to rack up some successful XP.

I went looking for a little premade DLG - but the eFlite Whippit is no more.

That brought me back to J&H Aerospace for another try.

The Carbonette is a balsa R/C boost glider. Complete with pop-pod. I happen to have one of the integrated micro receivers, and Josh directly compares the Carbonette to the Whippet. So here it goes. I’m not going to be as thorough as last time.

The kit came nicely packed. The videos are straightforward. The kit comes with more drawings than the Firefeather- enough to duplicate it.


As received, the wing does not have to joined for shaping. Josh must have gotten a bigger laser cutter. So the first order of business is to lay down the basswood strip on the leading edge, just above the bottom. And taper in the ends.



Then shape the airfoil. Josh suggests the Stanfoil, which seemed easy enough to shape. Mostly plane work with sanding to smooth and feather. Not seen in these pics is that I felt that I had planed a bit of a scoop into the forward surface, so I filled it with thinned CWF and sanded it back to shape.



After shaping, cut the wing, bevel, and rejoin. Once cut, it’s easier to see the airfoil.

 

[Charles_McG]

On to the fuselage.

Plywood over a balsa core. I put the tail channel fillers on the ply before putting the second ply side on. Josh put them in after.


Lay the tail boom in its channel, end flush with the spacers.



Measure and mark the fuselage 4 3/8” from the nose to place the wi g leading edge. I used the wing to mark the trailing edge so I knew where to stop gluing. Sand a flat spot on the bottom of the wing and join.


I measured as best I could to try and get the wings plumb to the fuselage. Then added fillets.




Add the pod catches to the nose, and shape.

 

[Charles_McG]

Airfoil the horizontal stabilizer. Watch the video closely for deciding which side is up based on where the control horn slot goes. I tapered the elevator and leading edge with the plane, then sanded smooth and rounded the leading edge. My sandpaper was a little sooty from cleaning up the laser cut edges.


Cut the elevator free, bevel so the angle faces the bottom.


Hinge. I used blenderm tape rather than the supplied material - for which I didn’t have the right adhesive. I did put narrow strips on the bottom side like Josh did.


Airfoil both vertical stabilizer pieces. I rounded the leading edges. Josh doesn’t mention this until after he’s gluing them in place. I think that’s the biggest oops in the video. I beveled to the right facing side. I think I did it correctly. I held up the part to the video, then flipped it - because I’m facing the screen and Josh is facing the camera.


More Blenderm. Single sided.


Mount the horizontal stabilizer. I used a counter to try and make sure I got it level.


I forgot to mention, the plane doesn’t work well to bevel the rudder pieces. I chipped out a bit, then switched to sanding.


The bottom vertical stabilizer glues directly to the boom.


And the other side, and fillets.


Eyeballing the squareness.


At this point, I took Josh’s recommendation to varnish the plane. It’s out drying.

 

[Charles_McG]

The pop-pod is pretty straightforward.

Plywood stiffeners and plane hooks over balsa core. I missed one photo.


Side plates.


Josh planes and shapes an angle into the pod tongue so the pod is off center compared to the vertical stabilizer. To try and limit exhaust burn. This was harder than it sounded. I think my idea of 45° was off. I tried sandpaper around the pod tube to do the concave shape, where Josh free handed it.



Alignment on a tangent was a challenge, but I think I got it. I cut a wedge out of scrap and filled a too-big gap where I had gotten the angle wrong. The shock cord is externally anchored and run.

 

[Ez2cDave]

Coming together nicely, Charles !

 

[Ez2cDave]

I went looking for a little premade DLG - but the eFlite Whippit is no more.

Charles . . . Apparently, the Whipit is still around . . . A company called "UMX" has become involved.

https://www.google.com/search?q=%22umx%22+%22Whipit%22&source=lmns&bih=927&biw=1920&hl=en-US&sa=X&ved=2ahUKEwipxo_dwdn_AhUaEmIAHedNANAQ0pQJKAB6BAgBEAI

Dave F.

 

[Charles_McG]

UMX is an eFlite product line.

You can get some of the parts - but not the whole plane. Not even on feeBay - I’ve got a watch set.

 

[BEC]

I have one of those in the stash (and the 12 inches). Good to see the build underway.

I've had mixed luck with Josh's stuff...but this looks really good so far. Thanks for sharing.

 

[Charles_McG]

After varnish and light paint. Enough to color, but the grain still shows through.

 

[Charles_McG]

Ok, here’s my thought. Pleased tell me if I’m crazy. Josh recommends a B6-4 or C6-5 for the Carbonette. But I’ve got this whole bag of AT 3.4s and D2.3s. And an Eggtimer Apogee. So what if I make an alternate nosecone to hold the Apogee and battery and run an ematch with a little powder down above the plugged motor? I’ll put the launch lug on a stand-off.

Then I’d be able to play with these C3s, AND get deployment/pop pop at apogee every time.

 

[BABAR]

And an Eggtimer Apogee. .

Then I’d be able to play with these C3s, AND get deployment/pop pop at apogee every time.

The enemy of good is better.

Sounds like a great plan for maximum altitude and possibly hang time.

Of course, the probability of lost rocket (in this case thermalling, how big and flat is your field?) is directly if not exponentially proportional to the following:

Time spent building the rocket.

Time spent FINISHING the rocket.

Cost of the rocket.

Cost of the HARDWARE and ELECTRONICS attached to the rocket.

 

[Charles_McG]

The enemy of good is better.

Sounds like a great plan for maximum altitude and possibly hang time.

Of course, the probability of lost rocket (in this case thermalling, how big and flat is your field?) is directly if not exponentially proportional to the following:

Time spent building the rocket.

Time spent FINISHING the rocket.

Cost of the rocket.

Cost of the HARDWARE and ELECTRONICS attached to the rocket.

Good points. I don't think thermalling is an issue for RC gliders - but pop pod recovery is something to consider. I'm certainly going to keep the option of flying as kitted. The only difference would be the launch lug being on a standoff.

 

[burkefj]

My only worry is low thrust and off vertical boost, the advantage of a pop pod and a B6 or C6 is hands off quick boost to apogee, now you are running 1/3 the thrust and if it pitches one way or the other due to wind or rod whip you will be stuck with whatever it does till you separate the glider which may be a long ways down range after 7 seconds of burn...

 

[TheAviator]

I would tend to concur. Save the R/C loads for a bigger *rocket* glider. This will fly great on the Estes motors.

 

[Charles_McG]

I mounted the receiver brick. Had a delay to go get hot glue materials. I generally think that hot melt glue is the worst adhesive ever - except when it isn’t. This hasn’t convinced me that it’s a good use case. I did have to extend the battery lead.




The tape marks are the aft Cg limit.

The really fiddly bit was getting the control ‘rods’ fished through to the appropriate sides and then connected up. Were I to do it again, I think I’d run the wires through the boom, tape them off to each side, and -then- mount the Rx-servo brick in place. For reasons I didn’t figure out, the elevator hook wanted to pull thru with any tension. I ran it in from the other side, and it’s fine, though it might add some friction.



The elevator needs a little more fiddling. Getting smooth travel around a transistor on the Rx took a little bending that took some trimming to cancel out. All of my elevator trim, actually. Which limits the down travel range.

I seem to have ended up tail heavy. Or I’m using a smaller battery than Josh. I had to add 3 1g sinkers to bring the Cg forward.


And with the nose weight, it actually behaved like a glider when hand tossing it in the back yard! I don’t have space to give it a good fling, but throwing it like a non-RC glider for trim testing behaved just like I thought it should. And elevator response was great. Rudder response was lack luster, but I may have simply been too slow. It floated pretty nicely. And didn’t break with a couple nose-bonks.

Next step is to paint and fit-tune the booster pod - and then try it out.

 

[Charles_McG]

I printed up a Cg jig from Thingyverse.

 

[Charles_McG]

Time for an update. I haven't gotten it in the air under rocket power yet, but I've still been working in that direction.

I double checked, and Josh was indeed using the 150mAh battery, rather than the 75mAh. And that explained the noseweight difference I noted above.

I've been watching a number of DLG videos. The NAR presentation on converting DLGs for boost, stuff from Armsoar, just starting in on Pierre Meunier. Among the things I picked up - why the Cg is so far back on the wing. (From reading here, I had anticipated ~ 25% back from the leading edge.) I gather that glider fliers like gliders to be really neutral - partly so they are responsive, partly so they indicate what the air around them is doing.

Last evening the planets aligned, and I had spare time, spare energy, and calm air, so I took the Carbonette over to the neighborhood park for a little more room than the back yard and tried throwing it into the air, rather than just straight & level tosses.

Firstly, I worked toward getting the trim when tossed back to having little to no elevator. That took a little extra noseweight, which I had anticipated and brought with. I easily got it to a really neutral point. Very straight in a short dive. Very little (if any) tendency to porpoise when level. It really holds the attitude you give it. It has terrific elevator response, but I suspect something is up with rudder. Either with my expectations, or the glider - I'm not sure which. With no rudder trim, the glider circles fairly gently to the left. That might not be terrible. It takes several mm of trim to straighten it out, and straightening it -all- out seems to make it harder to throw. So I'm letting it pull a little to the left. If I make hard rudder corrections, the glider seems to just ignore them. If I use a lighter touch (less throw), then I can turn gently to either direction. I'm wondering if full deflection essentially stalls the rudder.

Throwing at a gentle angle, so it's easy to pitch the nose down (or gravity does it for me) before gravity steals all the velocity, it's pretty darn easy to set a good glide. The glider might reach the top with a little roll angle, but a little twitch to the rudder and/or elevator, and it levels out and swoops along in loverly fashion. The neighborhood park might have more space than my backyard, it still has enough trees to bring a lot of glides up short. So it's pretty obvious I need more space yet.

The thin piano wire controls are a real limitation. They don't return to center very well. Especially the elevator - which seems to have a little more friction in the tail boom that I just can't get out. I did re-work the control horn connection to the proper side and got some of the slack out - but I've got very little down play. Luckily, it looks like I've got enough. I've developed a pattern of wiggling the controls down and right just before throwing in order to reset the center. That mushiness shows up in flying - if I do a hard elevator correction, then I get a little porpoising on the level that I have to tweak out - the elevator likes to have a little residual 'up' that's a failure to return to center, rather than trim.

The biggest thing is that I can't seem to throw it as hard as I think I should be able to. If I throw harder, the glider does a hard left roll and ends up upside down. Sometimes even further around. and the flight ends poorly. I haven't decided if there's something wrong with my throwing motion, or if I've got a little roll tendency sanding into the wing that shows up at higher velocity.

I spent about 90 minutes out in the park - and came back with no glider damage - despite some nose bonks and occasional tree branch. So far that's MUCH better than the Firefeather. I'm going to figure out how to mix in a little elevator with the rudder - and burn some Bs, baby!

 

[David_Stack]

Good Morning Charles;

Sounds like you are making progress and getting the glider to perform better, congratulations.

As regards your surface centering issues, it may be drag in the control runs from servos to the control surfaces, your control surface hinges 'binding', or it may be the servos themselves which are not returning to center. You may want to disconnect the linkage try and affix a long 'pointer' to your servo output shafts that you can index, and then run the servos through their throws to see if the pointer returns to the original start point when the sticks are released.

 

[Charles_McG]

I was able to trim a little bit of the body where the elevator line was catching a reduce the friction a lot. It still doesn't return to center quite perfectly - but it's better overall. And I got a more down-throw back. Not that I need it. The error in the system really seems to be a combination of play, bend, and friction, not the servo.

I figured out to mix some elevator into the rudder, too.

 

[Ez2cDave]

I've been watching a number of DLG videos. The NAR presentation on converting DLGs for boost, stuff from Armsoar, just starting in on Pierre Meunier. Among the things I picked up - why the Cg is so far back on the wing. (From reading here, I had anticipated ~ 25% back from the leading edge.) I gather that glider fliers like gliders to be really neutral - partly so they are responsive, partly so they indicate what the air around them is doing.

Firstly, I worked toward getting the trim when tossed back to having little to no elevator. That took a little extra noseweight, which I had anticipated and brought with. I easily got it to a really neutral point. Very straight in a short dive. Very little (if any) tendency to porpoise when level. It really holds the attitude you give it. It has terrific elevator response, but I suspect something is up with rudder. Either with my expectations, or the glider - I'm not sure which. With no rudder trim, the glider circles fairly gently to the left. That might not be terrible. It takes several mm of trim to straighten it out, and straightening it -all- out seems to make it harder to throw. So I'm letting it pull a little to the left. If I make hard rudder corrections, the glider seems to just ignore them. If I use a lighter touch (less throw), then I can turn gently to either direction. I'm wondering if full deflection essentially stalls the rudder.

The thin piano wire controls are a real limitation. They don't return to center very well. Especially the elevator - which seems to have a little more friction in the tail boom that I just can't get out. I did re-work the control horn connection to the proper side and got some of the slack out - but I've got very little down play. Luckily, it looks like I've got enough. I've developed a pattern of wiggling the controls down and right just before throwing in order to reset the center. That mushiness shows up in flying - if I do a hard elevator correction, then I get a little porpoising on the level that I have to tweak out - the elevator likes to have a little residual 'up' that's a failure to return to center, rather than trim.

The biggest thing is that I can't seem to throw it as hard as I think I should be able to. If I throw harder, the glider does a hard left roll and ends up upside down. Sometimes even further around. and the flight ends poorly. I haven't decided if there's something wrong with my throwing motion, or if I've got a little roll tendency sanding into the wing that shows up at higher velocity.

Hi, Charles !

(1) CG location - Good observation.

(2) Rudder behavior - I have a theory that the "slab sides" of the fuselage might offset the area of the Rudder, making it less responsive, or unresponsive.

(3) Left Roll / Left Glide - That might be an alignment / warping issue. Not a big problem in Glide BUT, under Boost, it might have a far worse reaction, than when you throw it hard. Better to discover things during hand-launch testing, than while under rocket power ! If the behavior is "speed Sensitive", it will only get worse, at higher airspeeds.

Dave F.

 

[David_Stack]

On a 'traditional' cross-tail DLG the horizontal stab/elevator is located on the boom ahead of the vertical stab/rudder, this allows the rudder to be 'full height'. Because of the tail configuration on the Carbonette that is not possible without installing some sort of 'joiner' that could drive a rudder located both above and below the boom.

I wonder if the model is simply lacking in rudder authority due to design...

 

[Charles_McG]

First boosted flight:



I decided that my roll-over was throwing mis-technique, rather than a problem with the glider.

It was low wind, bright and humid at Bong this morning when I set of my pad next to the A8 position and set the Carbonette up with a B6-4. Boost was nice and straight, and I pushed the nose over at the top. I thought for a second that the pod tangled at ejection, but everything fell clear, and a twitch to the controls leveled out the glider for a number of nice loops around the LPR pads. I had enough rudder authority for what I wanted to do. I didn't eke out the least bit of glide - I lost sight of the glider behind the LCO tent, and it nosed into the grass.

I'm chuffed as ninepence, and my biggest problem is that the pop-pod ended up in the pond and the motor is currently stuck in it. So only one flight for today.

I think I'll make three pop pods so I can prep a whole package of motors.

 

[TheAviator]

First boosted flight:

View attachment 599124

I decided that my roll-over was throwing mis-technique, rather than a problem with the glider.

It was low wind, bright and humid at Bong this morning when I set of my pad next to the A8 position and set the Carbonette up with a B6-4. Boost was nice and straight, and I pushed the nose over at the top. I thought for a second that the pod tangled at ejection, but everything fell clear, and a twitch to the controls leveled out the glider for a number of nice loops around the LPR pads. I had enough rudder authority for what I wanted to do. I didn't eke out the least bit of glide - I lost sight of the glider behind the LCO tent, and it nosed into the grass.

I'm chuffed as ninepence, and my biggest problem is that the pop-pod ended up in the pond and the motor is currently stuck in it. So only one flight for today.

I think I'll make three pop pods so I can prep a whole package of motors.

Congrats! You earned it!

The funny thing about R/C gliders (rocket-gliders in particular, but boost-gliders too) is that the turn around time for prep is very short. To the point that I can easily get six 6-minute flights off in well under an hour. Be careful, they really eat motors!

 

[burkefj]

First boosted flight:

View attachment 599124


Ended up in the pond and the motor is currently stuck in it. So only one flight for today.

I think I'll make three pop pods so I can prep a whole package of motors.

Yeah that's the biggest downside in boost gliders versus Rocket gliders, especially if you fly on your own or somewhere that has a surrounding field with very tall grass or water.