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Nov 19, 2002, 02:29 AM
high-speed freak
opualuan's Avatar
Thread OP

ultralight BUG setup

finally getting around to setting up the bug built so nicely by ergo60sx... tried to cram in some gws pico servos, yikes. put in an order for two westechnik 2.4g servos, should be a great fit. I also have a kokam 145ma li-poly, ~5g. I also have sitting around a SH&R rx (2g)... that's less than 15g of gear, about 2.6-2.75g AUW! nice...

but will it balance? where's the CG supposed to be? I'm thinking I'll have to stack the rx on the battery all the way in the nose, and actually put the wes servos in front of the bulkhead... thoughts? is there a limit to how light to make the bug to make it launchable?
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Nov 19, 2002, 05:08 AM
Registered User
ahh don't worry you can always stick a large lump of lead in the front
Nov 19, 2002, 11:37 AM
high-speed freak
opualuan's Avatar
Thread OP
kind of defeats the point of sticking $120 worth of servos in there and a $100 rx, though, don't ya think?

if I need nose weight even with eveything forward I'll swap the 2g shr rx for the 6g berg 4, very nice and compact but more reliable... but if I can use the 2g rx, great...

come on, ANYONE know the bug cg?
Nov 19, 2002, 02:09 PM
Registered User
hi there,
cg for bug is 2-3/4" to 2-7/8 " back of leading edge. If you have add weight, use aluminum it's much lighter! LOL
Last edited by dave rave; Nov 19, 2002 at 06:59 PM.
Nov 22, 2002, 08:25 AM
In the (inclined) loop
There is plenty of room for one of the servos in front of the bulkhead for my bug.

I've found that (obviously) the bug is pretty sensitive to cg. I found the optimum performance cg, and then moved it forward 1/8" to reduce accidental stalls. It took 6 grams (1/5 ounce) in the nose to make it balance.

Freytdog suggested a single line pull/pull system, using a micro bungi on the tails for one of the pulling forces. I tried it, and it eliminated any noseweight but was so difficult to keep tuned that I went back to ordinary pushrods.

Beginning this winter, a dozen, or more folks up here in Minnesota will be building bugs. There will be more than a dozen great new ideas/techniques/styles represented. I'll keep y'all posted.

Nov 25, 2002, 02:23 AM
Almost a Pilot
Mauilvr's Avatar
One useful change when your group builds thier Bugs this winter is to consider extending the nose at least 1/2" (or more) to help eliminate any nose weight.

Bear in mind the standard Bug flys VERY well at the published weight - which was with a 555 receiver!

An ultralight set-up should be interesting but also difficult in any wind.
Nov 25, 2002, 02:56 AM
high-speed freak
opualuan's Avatar
Thread OP
what IS the specified weight range? for nose weight I'm thinking of swapping in the 6g berg4 to replace the 2g SHR (higher selectivity and better range), and if that's not enough parallel a second kokam for longer flight time... I'm going to have the wes servos in front of the wing section as far forward as possible, should make a very clean installation with the wes's...
Nov 25, 2002, 09:41 AM
Almost a Pilot
Mauilvr's Avatar
The desired published weight was 3.5 ounces, which gave a W/L of only 3.09 Oz./Sq. Ft. The original article used a 555 (w/o case), 2 HS-50 servos and a 3 cell nicad pack. Not sure how big they were but probably 120ma or so. He apparently didn't need ANY nose weight.
It flys fine at up to 5 Oz. and even more in light air.

Biggest weakness I've seen (easily repaired) is the tail and fuse. The wing is VERY strong. I've always felt a light, thin fiberglass pod would be perfect for this very nice flying plane.
It really does fly well - I'm sure you'll enjoy it.

At that light weight it won't like much wind though.
Nov 25, 2002, 06:09 PM
Registered User
Zhack's Avatar

Been there, done that

Hey opualan,

I had the same brainstorm about a year ago when I built my BUG. AWESOME plane!! I used:

GWS pico Rx
50 mAh NiCd
CS10 servos

I initaially tried the Westek's but they didn't have enough torque @ 3.6V to move the tail surfaces reliably without bindin in the tailboom which leads me to my next point....

DO NOT use 1/4 or 3/16" CF for the boom. It's WAYYYYY to heavy! I used the 1/8" left over from the spars and that alone cut about 10grams of weight. It also REALLY helped to balance the lighter gear. If your gear is any lighter (i.e. wes Tke servos or Kokams, you'll need to stretch the nose up to an inch and/or cram everything in front of the bulkhead.

Mine came out at 75g with the CS10's and flies like a dream! I absolutely LOVE it but I still want to try a single Kokam 145. Not going to change the CS10's though. At the lower voltage, they are barely torque enough to pull up from a steep dive--Don't ask how I know

About recievers-- don't try to save weight by sacrificing range--you will lose this plane! It thermal unbelievably well. Like going, going, gone! I've had to park the stick in the corner and spiral dive may way back to earth more times than I can remember. With a SH&R Rx you'll range out just as you get into the good stuff.

HAVE FUN-- it's an AWESOME(!) plane.
Nov 27, 2002, 01:46 PM
Registered User


Where can I find info on plans for the Bug or a kit?
Nov 27, 2002, 05:54 PM
Registered User
Hi there GaryO,
try the RCM website , plans, # 1297
or serarch Carl Dowdy the designer, he may have a website
Nov 28, 2002, 09:26 PM
Registered User
RCM Website?? Doesn't ring a bell. Does anyone have the full address?
Nov 28, 2002, 09:47 PM
Almost a Pilot
Mauilvr's Avatar
Radio Control Modeler
Dec 06, 2002, 12:13 PM
Registered User
jrgospod's Avatar
Have some of the 12 new builders add an extra 3rd rib on both sides. Use the same spacing but just copy the plans and offset one rib and re-calc the CF rod placement. Leave the placement the same on the first and last ribs and just change the middle ones as needed. You get a lot more wing area without much added weight. It really makes a difference. Take a look at the Yahoo group.
Apr 13, 2003, 10:25 PM
Balls O' Wood
RV-4 flyer's Avatar
Originally posted by jrgospod
add an extra 3rd rib on both sides. Use the same spacing but just copy the plans and offset one rib and re-calc the CF rod placement. Leave the placement the same on the first and last ribs and just change the middle ones as needed. You get a lot more wing area without much added weight
Wow. i should have known that someone had already tried this. I just started a second bug with exactly such a wing. Good to know it works well.

I'm also building it with a cross tail and all the equip fwd of the wing l.e. bulkhead. Might try a gyro. Anyone have advice on how to SAL the bug?

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