Longhshot 4 DLG - Buildthread

[EraJomppa]

I will still have to get some carbon cloth and laminate that over the damaged parts of the boom in the base just to make sure it will not break easily.

Or maybe not?





I had some extra epoxy squishing from the joint and I smeared on to the damaged portion and now it has a pretty nice laminate of epoxy over it. I know it's not a structurally ideal, but I have my doubts whether putting a layer of carbon cloth over that would provide any extra strength to it.

Any ideas? should I be safe and add a layer of lightweight carbon and laminate that over the base of the boom or should I just leave it as it is, since it's already got extra epoxy all over (and under)?

 

[EraJomppa]

Longshot is finished!

Today I woke up and started to build. Now at almost midnight, I have finished the build! It's finally ready for the maiden.

Here's how the rest of the build went:


First I started by making the holes for the pushrods with a file.


Remodeling the servotray. I made some supports where I glued the pushrod sleeves into.


Test fitting the servos and tray. I had to go with servos like this since I couldn't get enough space for the servo arms if the arms were facing outwards, they would collide with the pod wall.



More testing and fiddling. I pushed the pushrods through the pod and glued the sleeves into the tray.


After that I put the tray into its position and with the help of magnets dropped some CA inside and glued the sleeves into the sides of the pod. (the pictures are not in correct order for some reason, I made the hole for the aileron wires earlier).


Glued the servotray. Then glued the servos in.


Fitting all the wires and centering servos.


I just used clear tape to attach the pushrod sleeves to the boom.


Rudder coming together. I used 5 minute epoxy to put all the control horns in place.


Here is the hole I made for the aileron servo wires.


Here are the wires with a 4-pin connector attached to them (grounds and positives are shared).


Oh great the order is really screw'd Here is the servo tray without the modifications.



This is how I attached the wooden supports inside the pod, magnets. And thin CA.




Making of the 4-pin connector and gluing of the aileron servos. I decided to tape them over and glue them with hot glue to the wing.


I decided to make pushrods like this all around so I can replace them easily and change the holes on servos and horns if necessary. Thin shrinktubing, thin CA and voila. Easy no-flex, no-slop pushrods. I used 0,8mm wire since the holes were that size, thus no slop at all.



More on the finished pushrods. I use the same technique for the rudder and elevator pushrods too.


Its pretty much done now!

The airframe came out at 280 gram, but it was tailheavy (no surprise there) so 20 grams of noseweight was required. With that it balances perfectly at 80mm for LE, which is factory default.
How all that is really left is get all the electronics tied down inside with the noseweight, don't want them to rattle around. Then program the radio, trims and such. Then it's maiden time and we'll see what after that! Maybe I will put that carbon cloth to the boom, I haven't decided yet. I'm not planning on tossing it hard on the maiden so I'm not afraid Ill break it without it just yet.

Shees I'm tired. More tomorrow! (Thumbs up for a good weather).

PS. Ill try to get in on video.

 

[EraJomppa]

Weather is looking good, but the wind is up 5-6 m/s at the moment so I will wait until it calms down in the evening and then I will go out and do the maiden!

Last night I stayed up another hour or so and established the control throws. I also centered the surfaces through the channel subtrims. I could get the ailerons really nice and centered, but rudder and elevator I kinda just had to eyeball and use a ruler.
-Rudder 15 mm both directions.
-Elevator 10 mm up; full throw down, 0,5 mm before it hits the boom. This I'v read is essential since you want all the down elevator for pulling down after the climb.
-Ailerons 12 mm up and 30 mm down. After that I set the actual ailerons to function 12 mm up and 6 mm down, this ought to give nice amount of differential. The flaps, or airbrakes, go down all 30 mm and are controlled by the throttle stick. Though I put that behind a switch so I can turn that off at take off and not accidentally use them when not convenient.
-Also I set up one position for the flaps behind a 3 position switch that gives bot ailerons (flaps) 3 mm down movement. I don't think I will use flaps or airbrakes at first but I wanted to establish the programmings so I can fiddle with them and copy them when I want to start using them.

I also used some tape to secure the lead weight at the nose and then I used some foam to pack packing to secure everything down nice and tight. I also made small holes for the antennas to stick out as "whiskers" to get best possible reception. I got telemetry to tell me the 1S lipo voltage and signal strength but I wanted to make sure I wont get any unnecessary dropouts. I will use a new canopy without the metal wire on it and just secure it down with tape during maidens, as I realized that I used too long wires when making the old canopy that I cant even close it down.

charging the camera...

 

[EraJomppa]

Yes! Maiden done and it flies! it flies so good! Though I'v barely even flown it yet but still it feels so locked in and it really has a lot of control authority in the air, even though its 5-6 m/s wind still out there. I will go out again at the evening to see if the wind has died down a little.

I had some problems, the pushrod that I made for the elevator got a bit loose and it felt like the rod had became longer all of a sudden and the elevator trim was WAY off, I noticed this as in a takeoff the plane just went behind me and made a backflip and I knew something was off. I threw it couple more times very gently and decided I need to fix it home. I redid both my rudder and elevator pushrod "clevises" and now they feel a lot stronger.

Unfortunately my camera is getting crappier and crappier as it grows older. It's a hobbyking "HD" wingcam. The files are watchable, though VERY blurry and off-focus, but utterly crap and any editing program I'v tried cannot edit them. so I have to do with screencaps from VLC.



PS. I'm not sure if I have mentioned this but I'm using the 900mAh 1S lipo as a battery and I have the telemetry receiver transferred to this plane so I can monitor the lipo voltage there.

 

[EraJomppa]

Okay, my fiancee tagged along and she took some video of me flying! Here it is:

Next up I might start to compile the most essential steps of this build into an article?

 

[rcspaceflight]

Next up I might start to compile the most essential steps of this build into an article?

Not a bad idea. Flite Test could certainly use some more DLG articles. I know a lot of people have expressed interest in it without many people sharing their experiences with it. (But try to keep the article relatively short and to the point. People like me tend to skip over the really long ones. Maybe just throw that video at the beginning and then some pics of the build with quick captions and ignoring the issues you had with re-gluing a portion of it.)

 

[xoration]

Very nice! Congrats to your maidden.

Just a few hints for your next project! For the Ailerons you should think about doing a Z-linkage this reduces flutter and you get more aileron travel.

About your throw. It looks good. But try not to run first stand still make your rotation and throw it straight and the horizon. And leave your neck strap at home.
Push your receiver away from your with a straight arm as well. David is explaining it quite good in the DLG video. And in your rotation try to use smaller steps (the last throw was ok considering steps).

The height of the plane comes out of your rotation and how much you are twisted to begin with. Just a few comments.

Regarding DLG articles I'm getting two new DLGs soon. A Stobel v3.5 and a Snipe if there is interest I can do a buildthread as well....

 

[EraJomppa]

That would be nice yes, I don't think there are too many DLG buildthread around ^^

My throws certainly need practice, but I can't take the neckstrap off until I can find some grip tape or something to prevent the radio from slipping from my hand I'v dropped it few times and I'm kinda neurotic about keeping the neckstrap on

About the ailerons, I think I should have made the Z bends on one end of the pushrod too. I wonder why I didn't? Oh well, they work really well, no flutter so far and I'm only using about 80-90% of the current throws. I got 30 mm of down movement on brakes.

I got my article posted, but it has been waiting for approval for a bout 2 weeks now. There must be some queue. I'll link it when it goes live. Nothing fancy really, mostly just and overview of my experiences with links to this buildthread etc.

 

[airhawk]

you don't see those batteries any more what were they called poly nickle hydrate or something on those lines

 

[xoration]

NiMH were used for long. But no it also switched to Lipos. Lighter, more flight time etc. etc. And you can load them a LOT faster.
The lipo is loaded in 1h nimh needs 12h.

And you get more flight time. With my dlg I can fly like 6h or something. I never even came close to the lipo beeing empty.

 

[EraJomppa]

Yeah, I could shove 3 of the 900mAh Lipos that I use there so I didn't have to use lead And with just one I get around 3h of flight and the voltage stays around 3,7-3,8V. I haven't tried how long they can go on, since I stop at around 3,8. The servos I got say they are good to around 3,3V, so I dont want to risk servos jamming due to low voltage naturally. Telemetry is a nice thing to have

 

[EraJomppa]

Okay, my article is now published:
http://flitetest.com/articles/longshot-4-dlg

If you have time, go check it out and leave a rating/comment. I'd like to get feedback if possible

 

[bjornal]

Hi and thanks for a very informative thread.

I'm about to order myself a Longshot 4. What hardware did come with the plane? Will I need pushrods and sleeves for tailplane? I'll likely use carbon rods for ailerons together with CA and shrink wrap for a bulletproof non-slop fitting there.

 

[EraJomppa]

Tail pushrods and sleeves are included, but nothing for the ailerons but the control horns.
You are going with a similar approach with the ailerons as I did I see. Though I did use only steel wire and no carbon. I felt like it was too short distance to bother with weight savings that using carbon might give.

Good lock with your build and feel free to post your own build here!

If you got any questions about the build then post them here so I can try to answer them and everybody learns

 

[zebu]

Thank you

I ordered a Longshot 4 for last Christmas and I'm searching here and there some information to build it the best I can.

Thank you very much for this buildlog.
It helps me to find some answers.

Are you happy with your aileron servos ?
I'm not sure about which brand/model to use.

I heard about Dymond D60, MKS DS-75K, Hyperion DS09... but no real feedback about them, the pro and cons.
Review on MKS are good but they are (too) expensive for the use I think I'll have of this first DLG.

Cons for the two other are their thickness : 9mm.
I would prefer use servos that don't stick out from the wing (even just a little).

I also found the KST X08 V3. They are 8mm thick, not too expensive, all metal.
Do you have any advice on which model to use ?

The servos you use seem to be ok even at low voltage, I think it's a good point for them.

 

[vipero00]

I just started a build. I bought these on a recommendation from the store.

 

[vipero00]

A question about channels on the Longshot 4 DLG

To quote the manual: "Five channels are required on the transmitter if 2 aileron servos are fitted in wings."
I am asuming that they mean two servos/wing for a total of 6 servos. Is this to enable crow?

 

[Craftydan]

Not quite. Most mid-range DLGs (which the longshot fits in) when built out to their potential are 4-channel airframes, but most radio systems reserve throttle as it's own channel. There are a few radios (like the taranis) which can easily reassign the throttle channel to a second aileron, but most radios can't, hence their warning that you'll need at least 5 channels.

Effectively you have Rudder, elevator, left and right aileron. With proper mixing and a clean airframe you can get the plane to fly like the shark-of-the-air it is with just this. The flaperons alone will give you good camber/spoiler control to run to lift and slow to near stop inside, then at full down deflection should give you more than enough drag to bleed off energy and drop her right in your hands, every time. The extra pair of servos to implement separate flaps/crow simply aren't worth their weight, angular moment and linkage drag -- they'll rob you of launch and glide performance for no real gain.

 

[Craftydan]

Vipero,

BTW, Looking back through this thread . . . are your aileron hinges on the top or the bottom of the wing? They look like they're on the bottom skin, which allows you to do something quite a bit cleaner for the build, called "Top-Drive" this allows you to nearly completely embed the linkage inside the wing, which has a dramatic improvement in launch and glide performance.

If you haven't cut into the wings and are interested, I think you might want to look into it. Ask, and I'll be glad to help you with it.

The tail linkages could also be improved with pull-spring links (lighter tail means less nose ballast, means lighter plane overall), but you might be able to swap that out at some future date.

 

[vipero00]

I'm game for Top-Drive

Vipero,

If you haven't cut into the wings and are interested, I think you might want to look into it. Ask, and I'll be glad to help you with it.

Hi Craftydan,

I think I'll give it a go. Since the pre-cut bays are a little large should I fill them in with something?

Here's a pic.

Norm