Easystar 2 modifications for long range/duration

[stevec]

Hi all I thought I'd start a thread regarding a little project I thought I'd have a go at before I embark on a twinstar.

The plan is to make a tidy clean and efficient battery lugger out of my easystar.
I recently got a tbs crossfire so I'd like to make the most of the link budget.

First step is to hollow out a compartment behind the prop that I can house a 3D printed box for the xfire. The box will be glued in to restore strength this enables me to run the rx sunken into the fuz for a more slippery profile.

Next I have some of the zippy compact batteries on order 25c 2700 mah. 2 for £25 delivered from hobbyking uk.

These will be mounted into 3D printed boxes that are sunk into the wings. The power cables running into the fuselage to connect with the 6100 battery mounted on the cg.
In order to fine tune the cg I may relocate the servos to the tail but I'll see how she balances first.

So I wil have 2 2700 and 1 6100 pack.

The big question is will it fly like a pig with that much weight on it... We'll see.
The canopy I printed recently will be used for the apm, flight cam, go pro vtx and gps leaving the whole fuselage open for whatever I can squeeze in. If I want to run it light I can just use the 2 2700 packs or I can add from any of my other 3s packs to fine tune the weight.

I may program flapperons to help her slow down but I'll wait and see what she flies like first.
I was just going to go all out on a twin star but I thought I'd try out the battery in the wing idea on an old airframe first.

Pics to follow

Cheers
Steve



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[stevec]

Some photos



Crossfire housing servo lead come in through a hole drilled through to the battery compartment


Fpv apm pod



And finally this battery is pretty much the same dimensions as the compacts I have on their way...


The battery box will rest right next to the spar I may even print it with some location hoops for the spar. I am also playing with some designs to let the battery boxes interlock to give some extra strength.

The easystar is the first bird I had with Fpv and it has lots of hours on it so I am not too worried if this fails miserably but it would be great to get 60 minutes of flight time out of it.
Not sure where the point of diminishing returns will be on the weight side but I have had the big 6100 pack in it for a flight with the go pro on it and the wings did flex around a lot. I may extend the spar 6 inches or so each side but I'll wait until I have flown it.
The battery box will also have the same profile as the top of the wing so as to maintain as much lift as possible.

/Steve


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[BlueFlyer]

When I first read that you were doing a long range/endurance build from an easystar 2, I was starting to roll my eyes... but now I've read the post properly I'm really liking this idea, I remember you talking about the lipos in the wings idea and I was all for it.

Honestly though, I don't think an easystar could cope with the weight of 11.5Ah of 3S battery.

If it were me I would fly with a much smaller LiPo in the belly at first, with the main "test" being the handling of the plane with the LiPos in the wings... then slowly increase the size of the belly LiPo.

Heck, just throw a 2200mah in there first, power the FPV gear from it's balance plug or something.

All in all, I'm very interested in how this pans out, absolutely LOVE the idea of having LiPos in the wings and I will be keeping a very close eye on this as it develops.

good luck with it buddy

[BlueFlyer]

Another Idea if you truly want an endurance machine, is to ditch the GoPro.

I have 2 canopies for my Skywalker... the original foam one that just has a small FPV camera on it, and a wooden canopy with my GoPro and FPV cam on... the GoPro is for my chases, cloudsurfing and low level close in stuff, stuff I'd want to capture in HD and put on youtube for example... the foam canopy with just the cam is what I use when I'm doing distance runs where the footage is pretty much boring really... for 2 reasons

1) if anything goes wrong, the value of my loss is almost halved as £300 worth of GoPro is safely in my pocket/toolbox ;)
2) foam canopy is about 200g lighter than the wooden one, that's pretty much the weight of a 2200mah 3S Lipo, less weight with same LiPo loadout = longer flight times

[stevec]

Funny you should mention that I was thinking tonight about redesigning my apm holder to take a möbius instead or maybe even an old 808 #16 cam I have


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[stevec]

I already get 30 minutes flight on average from a 3s 2200, the 2200 batteries I have are too fat to go in the wing.

that is why I have gone for these zippy compact, they enable me to box them in without changing the outside profile of the wing at all.

I am wondering if flight characteristics will be better having the weight in the wing. A bit like unsprung weight rediction in a car. because the weight of the battery will be incorporated in the lifting surface and not acting like a pendulum 3 inches below the CG.

I am currently printing up a mobius adapter for the Canopy which will reduce the weight a lot.

Postman should be here soon with the batteries so I can then crack on and design the boxes for them.

/Steve

[FlyingRock]

Hi Steve,

any worries about having the gps puck so close to the 2.4 Vtx?

Cheers

Charles

[stevec]

to be honest I am more worried about it being close to the gopro. but I had the go pro recording and the whole lot powered up and got 12 so it looked ok. but real life always wins over testing...

if it is a problem I can always extend the cable and stick it out on a wing.

I am going to be going slowly adding things and with the weather the way it will be for the next few months I am not expecting quick results.

/Steve

[Billy_boy_2010]

I am wondering if flight characteristics will be better having the weight in the wing. A bit like unsprung weight rediction in a car. because the weight of the battery will be incorporated in the lifting surface and not acting like a pendulum 3 inches below the CG.

I rather think your unsprung mass analogy is a little off. Reducing unsprung mass on a race car is hugely beneficial for sure. But you're placing the batteries......

a) high up, above the CG in one plain
b) out on the wings, away from the CG in another plain
c) on the CG in a different axis- which is good because you should be able to add and remove with no change to the planes CG on that axis.


However, point a isn't good IMO..... Having the CG higher up will make the plane more likely to tip and roll. On a fighter or sports plane this cant be a bad thing- but for a stable cruiser, it will make it more twitchy and perhaps toss it around more in wind. Think of it like removing some of the weight from a yacht's ballast.

Point B isnt ideal either- by placing weight out on the wings- you will probably cause some undesirable moments and make for less predictable handling. A more extreme example would be to put the batteries right on the wing tips- im sure that would really mess them up. To have them just slightly out on the wings may not make much of a difference, but it's still a comprimise.


As Blue says- if you want efficiency and long range- i would get rid of that damn gopro and use a mobius- preferably one with a lens extension so you can have everything super stealthed and aero. Put a canopy back on it too.

Finally- i suspect your efficiency will be limited by the small prop of the easystar.- particularly as it will be working quite hard carrying all that extra battery weight. If you could mount the motor higher up, it would allow you to use a lower Kv motor spinning a bigger prop at a lower kv- which should work out more efficiently too.

[stevec]

good points all well presented,

I am not too concerned about the CG being wider after all this is a cruiser and I hope it will negate to some extent the fact the CG will effectively be higher, but don't forget this is to open up space for more batteries inside it.

I have just finished printing a mobius mount for proper long range flying, the thought of losing a £350 quid camera doesn't appeal.

my batteries came just now so I am designing the boxes for the batteries to go in the wings.

If this works the eventual aim is to use the same ideas in a twinstar or something similar.

will update as things come off my printer!

/Steve

edit: higher motor mount is on the cards after the rest of the mods. I am using a APC prop instead of the folder now as I doubt it will be off for gliding much!

[BlueFlyer]

Here you go... http://smallpartscnc.com/index.php?route=product/product&path=20_135&product_id=125

I put one on my Bix3 allowed me to have a 1200kv motor and a 8" prop for a bit more efficiency than the 2200kv/6x4 setup

I would say definitely keep some weight in the belly, the whole "pendulum" effect you speak of is the very thing that keeps the ez*2 a stable aircraft.

Like Billy says, and I think you've already decided on this, keep the wing LiPos as close to each other as possible. I see by your picture you intend to have them right at the part where the 2 wing roots join together... its the ideal spot I reckon.


All in all, I'm very interested in how this pans out. Good luck

[FPVSteve]

The position of the batteries above CoG is not an issue.... I know this because I put my motor miles above the normal mounting place in a bizarre experiment involving a 10" prop on my old EZ*.

https://www.youtube.com/watch?v=9CrJeZt7IzM

:laugh: :laugh: :laugh:

It did NOT end well, the plane was all over the place in the air ... but it still flew! I think the batteries at the wing line will be fine, they have virtually zero leverage.

It'll be weight that causes your plane to fly strangely and it'll simply need to go faster than normal.

[stevec]

Love the video!!


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[stevec]

Final shape of battery boxes
As you can see the inside too ends have a hoop for the spar to run through.
I used a copped down rg15 airfoil shape to give me the curve and it matches pretty well.
Tomorrow I'll run off 2 battery boxes...


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[stevec]

Right update time...

I have finished the boxes and hot glued them into the wing.

There are a few bits missing but all the heavy stuff is on there and it weights 1.5 kg with 3 2700 mah lipos in it.


Feels pretty heavy to me but no worse than when I had a go pro and a 5900 single pack in it. The cg is quite rearward so I may need to rethink the rx location on the boom but once I have all the kit on board I reckon it will be ok.
There is going to be a little bit of drag from the wing boxes where they protrude due to the wing taper but  I think it is going to work.

I have no idea when I'll get a test flight done doing surveys with the inspire 1 is taking up most of my time but if the weather ever clears up I'll try and get out.
Cheers
Steve


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