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Gryph is the expert on all things Mega so I leave the motor questions to him. Here is a pic of the adapter plate that goes in behind Pete's mount and bolts up. The reason for the plate is that it is a totally different bolt pattern than the P32 but I can pull this out and throw a P32 in at any time.
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Mega 16/60
I like Mega motors, but have to admit that I am not well versed in anything larger than the 16/25 "green" motors. Your motor choice is definitely "different". Is this motor/gearbox touted as being suitable at 4k+ watts? If I remember correctly, you are planning on a 6s (2x-3s) set-up? I cant wait for the maiden, as this thing is going to be very very fast at anywhere around those power levels, let alone even more wattage. These larger birds are far easier to manage at extreme power levels, similar to touring cars. Sleeper looks, awesome performance, and the ability to do so many things superbly! Flight times are easily over 10 minutes with 1-2 minutes of actual motor-on time. Truly opens up another dimension of flying. You need to take a photo of that big smile on your face after your first maiden. I'm sure it will look something like this>
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It Balances!
Yes....it balances at 75mm which is in the center of the large carbon joiner...what that gives me I have no clue. Don't think anyone as yet has built it for other than electric assisted sloping. I have searched the forums and found no hotliners so no help on the CG other than the good guys at Esprit telling me they flew theirs at the center of the spar.
I included a pic of the gear inside...it will start life (or possibly end life) with 8S two TP 4S1P 2250's a Ice 200 with a major hair cut and the Mega 16/60/1 PG28 6:1 combo that is rated on the case at 4kw. The flying weight when I give this baby a throw will be 2912 grams or just a bit more as I plan on adding a second heat sink. Seng - I am half tempted to bring it down there and maiden it at your field. Obviously the apprehension in that first toss...to much throttle, not enough, not enough head wind and MAN this thing feels heavy I heard you say that on one of your videos. One other thing I did was to remove the down thrust put in by the makers....it is now 0/0 with the wing. |
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Last edited by arcticflyer; Sep 17, 2015 at 04:29 PM.
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What is the advantage of eliminating the thrust angle??
Ted |
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Quote:
http://adamone.rchomepage.com/cg_calc.htm I've found over time that you kind of develop a personal preference or feel for how you like your model set up (within practical limits). Either expressed as %MAC or %static margin. Once you have a target % its just a button click away to enter your new, unkown model geometry to grind out a c/g (and more importantly a c/g range). Our F5D's had 'not too many' millimeters of range on the relatively narrow chords & what was being asked of the models turn performance wise. Messing around too far out of range typically leads to bad things. The joiner/spar rule-o-thumb probably reverts back to olden days where spar is located ~airfoil max thickness (for strength) & assuming rectangular-ish wing & Clark-Y type airfoil (picture Piper Cub)... works out to ~25% MAC (safe c/g starting point but often averages 30-35% on may types of planes). None of these assumptions necessary apply to a modern performance moldy. Take one of your good flying existing models as an example, back calculate the known c/g to equivalent static margin% & use that as a target starting point. And if you have a funky swervy-curvey wing planform, you can always revert to old school methods (last line on this link) http://www.southernsoaringclub.org.z...ic-design.html As is often the case, a mathematical solution has a physical equivalent for those not too keen on maths. If you cut out a precise scale plan of the wing from stiff card and balance it on a knife-edge parallel to the chord, the line on which it balances is the MAC, and the AC is 30% back from the leading edge. A wooden dowel is easier to use as a "knife edge" as it can be rolled gently to achieve the balance point. |
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Blitz - I don't know the airfoil...it would be the standard one for the Tomcat. I kinda followed my rule of thumb with all my HP builds to go 0/0/0 hopefully I didn't goof up.
ptxman - Thanks for the info I found a calc a while back that after entering all the values gave me 75 but I can't remember what that value was for. There were three or four values given. I am going to toss it at 75mm and adjust from there. Maiden could possibly be on Monday if the weather is good and wind direction is good at the field. |
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I'm 99% sure its too big but I hope my MVVS 960 Redline motor fits the Tomcat. It's like 37 mm.
I've seen a few guys use car wax on their gliders, and in one case, Johnson and Johnson Baby Oil. What is the purpose/advantage to this?? Ted |
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It will fit...lots of room in the nose!
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That's good news. This motor has a fan so I'll be interested to see how much air it can move inside the canopy.
Ted |
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Sorry for the delay guys....really bad day yesterday...first knocked soldering iron off the table and tore out the wires for the handle...soldering iron down
To make matters worse I got the plane ready for some static tests and was walking it out the back door tail first and.....BAAM...hooked the tail on the door and folded the right tail nearly in half in a split second...my heart sunk and I wanted to launch the plane out into the woods power off..... stupid,stupid,stupid...BUT, I called Paul at Radio Carbon Art told him what happened and he walked me through the repair What a great guy thanks Paul! I will be shopping on his site One hour later a half bottle of medium CA...and packing tape...and so help me...am flying this thing in the next day or so. Emailed Lily at RCRCM and a new tail is already on the way Today got the throws put in, balanced the thing for 1000th time and did some static runups getting used to using the camber lever for throttle. AM REALLY CLOSE |
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dont feel bad
Did exactly the same on the weekend. After a fantastic day n 3 lovely flights with a 1\4 scale model, I walked one side of the elevator full on into the corner of the wardrobe door, crunching n splintering of balsa, couldn't look, put it down n just walked away, blah
Good luck with the maiden, all your bad luck has been used up |
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I'll get those numbers for you tomorrow...already packed it into the vehicle for the trip to PA tomorrow. The field up there is perfect for maidens...wide, long, with great approaches and no obstructions.
Mustfly - You have my sympathy as well....dumb thumb is one thing...carrying it though the house was a hard pill to swallow! |
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