Building a MultiPLex E-BIgLIft
 

hello e-fliers,
i just want to show how to build the very successfull almost antique BigLIft from the 1970 as an up-to-date version with e-motor.

the BigLIft was originally constructed by multiplex. the BL has been a very popular model since many years because of his very good flying characters.
suggested for a 10ccm glow engine the plane was capable to tow smaller gliders either behind or on top. the orinal plane was one of the most famous planes for beginner to get into bigger planes where you could do towing and dropping bonbons.

i had in mind not to build the lightest version but a very reliable and still strong for forgivness and still able to way outperform the same plane with a glow or gasser. engine. some people put a 20ccm or a 30ccm engine on this plane, so the engine itself would almost surpass the estimated empty weight of my e-version.
some data;
wingspan: 220cm
length:159cm
estimated weight w/o battery: 2500g

attached the original looking version from 1970 something and the new version 2010

RE: Building a MultiPLex E-BIgLIft
 

lots of cutting for the balsa sticks to build the fuselage sides.
all are 8mm. this structure builds later stiffness and lightweight at same time.

RE: Building a MultiPLex E-BIgLIft
 

ok today we gonna stick all together. alignment is important.
you can see already the battery tray. there is enough space to put from 3s up to 10s if you need it.
all plywood is 1.5mm. critical positions are enforced with layers of playwood.
most is glued with wood glue. this glue gives still some kind of flexibility other than superglue.

RE: Building a MultiPLex E-BIgLIft
 

ok in the meantime i build the landing gear.
i took some carbon unidirectional tube und put at least 15 long and 15 horter CF rovings in it.
first i saturated the rovings and then put them all together into the CF tube.
i sounds a messy work but it isnt if u spread the CF tube before putting the rovings in it.
then saturate evrything on ur workbench and put it in your gear molding form.
before put some thin glassfiber to get a nice surface and it will hold the CF tube better in place.

RE: Building a MultiPLex E-BIgLIft
 

ok back from flying this weekend here only a few details how to build a strong solid fundation for the landing gear. very timeconsuming work to cut all those holes in the plywood side reinforcement. every gramm (ounce) counts for the optimum result.

RE: Building a MultiPLex E-BIgLIft
 

some more details from the fuselage

RE: Building a MultiPLex E-BIgLIft
 

engine and controller arrived

using a Scorpion S-4025-16 332U/V and Kontronik Jazz 80AMP, calculated prop will be around 16x10 or if more thrust needed up to 18x8/10
this will give plenty of thrust from 3kg up to 5-6kg static

RE: Building a MultiPLex E-BIgLIft
 

got the fuselage ready. isn't it loking nice?
i had some balsa over, thats why i made two of them... ;-)

RE: Building a MultiPLex E-BIgLIft
 

it looks like iám posting for myself ;-)
is there anyone want to see still the results or should i shut-off ?
may be its the wrong threat.

RE: Building a MultiPLex E-BIgLIft
 

No way....this is great. I especially like the gear you made. Keep it coming.

RE: Building a MultiPLex E-BIgLIft
 

ok still someone is interested....
it is not the most complicated build but the results should be outstanding compared to the standard ARF plane, as much as i can say.
and probably as you should know, the lighter the plane the better it is flying. especially if you convert it to electric.
for standard pattern flying there would be around 100 - 150watts per kilo enough. so you should be able to fly this thing with 300watts.
put a 3s 2000mAh lipo in and fly drawing 30Amp for 4minutes. but you dont need to pull always full Amps. the average would be 10 so that will give you around 10min. time with reserve. Amazing right? but i wouldnt do that because power is evrything.
my motor is a 2000watt rated outrunner wich i will run with 6s at 6000U/min. with a 16x10 prop this gives my a calculated speed for 60m/s and drawing around 40amps.

here u see the elevator and rudder. they all are made in double T-construction. the stab is made in one piece and elevator is reinforced with a carbonfiber tube for better torsion stiffness.

RE: Building a MultiPLex E-BIgLIft
 

hello, sorry for being some kind of absence here...
here in miami is to much stuff going on weekends, either flying or beach with the kids.
i finished the wings! cutting all the ribs is the most anoying job and than sanding all the balsa sheetings.
this will shorten my life definetly for a few years. but its worth - now we see some real progress.
the ribs are of 2mm and the sheeting is made with 1,5mm. the struts are balsa 8x8 with some CF roving where the strut
from the wing to the fuselage is conected. to facilitate the servo cabling later some straws are glued in.
servo cabling is made with raw copper wire. this saves some gramms.

RE: Building a MultiPLex E-BIgLIft
 

Very nice work. Looking great.

RE: Building a MultiPLex E-BIgLIft
 

Please keep posting! I'm interested! I have a Big Lift II kit which I plan to build one day.

The model airplane club I used to fly with had one that they used to tow sailplanes. I was told that it had been in service for 25 years. Very impressive plane. I had started building one some years ago, but didn't finish. Gave it to a German friend. I believe it is in service some 15-years later.

I would like to buy a second kit if anyone has one to sell.