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Thread OP
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Discussion
Loaded dice 2 at 78%
I thought this might be of interest here and hopefully it will mean I can ask a few peoples thoughts whilst head scratching!
Having returned to the hobby after a long layoff (about 20 years), I dusted off a set of loaded dice 2 plans that my dad and I build about 22 years ago an flew for the last 2 years I was flying (what better model for a 4 year old right...) I had one slight problem in that I no longer live with my parents and my partner has set a limit on the space I can build (make a mess) in. The original dice at 191cm long was pushing it a bit as my bench is 150cm, so I have got as far as the picture building a 78% version of my beloved loaded dice. Plans so far is to try and get it to weigh in at no more than 3000g ready to go (about 6.6lb) and fly on 6s and anything up to 1300W. Everything so far is from scratch. All foam cores have taken a few goes but I'm happy with them now, I've adjusted the fuselage to add a battery bay with a big hatch that is the entire canopy and two hitec HS-225's are going at the back to look after rudder and elevators on short push rods - or that is the current plan at least. If anyone has any thoughts or better ideas I'm open to anything people would like to throw in, I just wanted my trusty dice back, even if it is more 46 size than the last one that had a ST91 (I think) up front..... If this one flies anything like as good, maybe with slightly lower power: weight I will be very happy. |
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Thread OP
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Sorry, quick photo with the original plans underneath to add scale!
The next thing I need to decide is if I want retracts. The fuselage is currently 600g complete, cores are 120g, balsa to skin them 200g (total of all the sheets before cutting) so I am on for 1800g of model and 1200g of electrics for my target. Retracts might blow the budget by about 100g but the original looked so much better with them! Every bit of weight means more flying time and electrics being pushed less hard so I am very much on the fence with this. |
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Last edited by stevecook5; Jul 23, 2021 at 08:35 AM.
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Thread OP
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Hopefully I won’t totally destroy them here.....
Been a busy(ish) week of building, got all the surfaces skinned and tail mounted. Will have to make an elevator joiner, thinking 4mm (8swg) piano wire as I have some handy from there U/C, think it will be enough? In other news, I have been spending time confused by servo choice. This is going to be 58” long and 52” in span on a 6s lipo setup swinging a 12/13 x 6/7/8 prop, which places pitch speed at around 110km/h (70mph) and will draw around 50-65A. From what I can see this places it in a similar, if lower powered position (1200W v’s 1800W) to the extrteme flight 60” models. So, I am thinking of something like a Hitec-5245 on rudder and the same on elevator plus the same or maybe 85’s or 225’s on the ailerons. I’ve had a look on a couple of servo calculators and that seems ok torque-wise. Tempting as the 7.4v mega units (savox 1260’s or hitec 7245’s for example) I cannot see the point of going this big as I am just not that good at this! |
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I'm assuming your going with digital servos. Any quality servo in the 40 to 50 in/oz range will more than suffice. Ballistic 60 sized airplanes going at higher speeds were regularly flown using analog 48 in/oz standard servos without any problems. Sure, you could spend $400 in 161 in/oz brushless servos for your 58" x 52" plane, but, what would be the point? My advice is, keep it simple (and reasonable $$$)
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Last edited by RC YEAGER; Jul 25, 2021 at 05:28 PM.
Reason: Typo
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Thread OP
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Thanks for putting my mind at rest! I think I can be a bit too safe sometimes...
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Thread OP
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Thought I'd put this here to not move the elevator link thread off topic:
After some good conversation about model weight and me getting further in the build/ adding some extra lightness I'm looking at 2400g (5.25lb) take off weight. Depending which measure you prefer this means a wing loading of about 22.5oz/sqft or a cube loading of 12. Both seem reasonable so with a bit of luck we are on track for a reasonable model. Of course it means a slightly higher stall speed so I'll prop with something that has a little more pitch and go from there. Motor data reckons a 11*9 or 12*9 will get the power where I'd like it for this weight at about 190w/lb. If anyone has thoughts on these numbers please do share, it's been a while since if flown anything designed more for aerobatics and I'm just trying to figure it all out. |
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Last edited by stevecook5; Aug 04, 2021 at 03:18 AM.
Reason: Typo
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>>After some good conversation about model weight and me getting further in the build/ adding some extra lightness I'm looking at 2400g (5.25lb) take off weight. Depending which measure you prefer this means a wing loading of about 22.5oz/sqft or a cube loading of 12. Both seem reasonable so with a bit of luck we are on track for a reasonable model.<<
Now you are moving into a much more "reasonable" area for a .25 to .40 size pattern plane. >>Of course it means a slightly higher stall speed so I'll prop with something that has a little more pitch and go from there. Motor data reckons a 11*9 or 12*9 will get the power where I'd like it for this weight at about 190w/lb. If anyone has thoughts on these numbers please do share, it's been a while since if flown anything designed more for aerobatics and I'm just trying to figure it all out.<< With 190 watts per pound you should do fine with aerobatics. Have you use eCalc online? When I build an electric pattern plane I will plug the information into eCalc for an estimation on the performance. It did turn out very close to reality. https://ecalc.ch |
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