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rhovie
04-17-2006, 02:04 AM
I built a 4*40 conversion to electric using an AXI 2826/10 motor and TP 4200 batt. The power seems fine for sport/aerobatic, but the roll rate is sluggish. I wondered if I redid the wing with less dihedral (maybe none), would help. I would change the standard one-aileron setup to dual aileron servos. I could also clip the wing, but not sure if that would be helpful. Thanks for any help, R. Hovie

Twmaster
04-17-2006, 02:23 AM
Have a look here. Most of those mods are covered in this thread (http://www.wattflyer.com/forums/showthread.php?t=1367). It's a tad long but loads of good 4* info there.

jonnyjetprop
04-17-2006, 03:57 PM
Check the thread that was posted, but its common for the guys to cut off a bay on each side of the wing.

John

Dereck
04-17-2006, 05:23 PM
I built a 4*40 conversion to electric using an AXI 2826/10 motor and TP 4200 batt. The power seems fine for sport/aerobatic, but the roll rate is sluggish. I wondered if I redid the wing with less dihedral (maybe none), would help. I would change the standard one-aileron setup to dual aileron servos. I could also clip the wing, but not sure if that would be helpful. Thanks for any help, R. Hovie

Fastest fix in your position - remove one bay per tip and replace the ailerons with ones 3/8" wider than stock. If you built the model using the kit's suggested aileron cross-section, that half round TE section on all the controls makes one wonder just what they were thinking off. Make your new ailerons with squared off TE's

Reducing the dihedral would make a real mess of your model - from the added weight of reinforcing the re-joined centre to screwing up the yaw/roll couple balance of the design altogether. With a shorter wing and more aileron power, the 4* will knife edge very well, with minimal coupling between top rudder and roll input. Lowering the dihedral will cause the model to roll in the opposite direction to rudder input - which in knife-edge, causes the model to roll towards the inverted. Not fun at all, been there, ironed the teeshirt... :eek:

If you're still feeling frisky after that, the next good mods are a 25% larger tailplane and around 50% more rudder...

It's a real tribute to this great design that it takes whatever we amateurs throw at it and it still flies just great.

Hope that helps

Dereck

rhovie
04-17-2006, 11:12 PM
Thanks Mike N, John and Dereck: The wing mods especially look good--I guess I won't fool around with the dihedral! Had a Goldberg T2 and liked the way it flew, but I don't see any posts about an electric conversion for it. I would expect the power system for the 4*40 would work? R. Hovie

Dereck
04-18-2006, 12:46 AM
Thanks Mike N, John and Dereck: The wing mods especially look good--I guess I won't fool around with the dihedral! Had a Goldberg T2 and liked the way it flew, but I don't see any posts about an electric conversion for it. I would expect the power system for the 4*40 would work? R. Hovie

From vague memory, the T2 is a little bigger on the wing area, but should cope on 4*-ish power if a gentler lifestyle is satisfactory.

The lowest power my dear old 4*40 flew on was an AF25G cobalt running 16 cells - only around 500W. It last had a Hacker B50 on 16 cells x 45-ish amps - now that was fun! It's a bit dated now, but when I flew it regularly, it was instrumental in suggesting to many slimer drivers that maybe it was they who had the lack-of-performance issue ;)

Possibly the 4*40 is the best all-round electric sports aerobatic model available? Shame there was never a "legit" 4*20 for the 10 cell / 3S lobby?

Regards

Dereck

jonnyjetprop
04-18-2006, 01:25 AM
The Tiger 2 would also make a great conversion. I've seen only a couple of posts about it.

John

CorsairJock
04-26-2006, 03:57 PM
Check the thread that was posted, but its common for the guys to cut off a bay on each side of the wing.

John

Yes, what he said.

I haven't built a 4*40 in quite a few years, and haven't done an electric one. Someday I will.

Way back when they 1st came out (20 years ago?) I built several of them. Each one had the outer wing rib bay eliminated, reducing the span to 54".

Even so, it was still great at flying slow, and very easy to land. I won more than a few Fun Fly event with them. With the reduced span, they have better acrobatic capabilites, including better roll rates.

The only way to go, IMO.

rhovie
04-26-2006, 10:58 PM
Thanks for the wing mod tip--I did that mod on a BTE e-venture 60 and noticed the difference. That will be the way I'll go, plus perhaps widen the ailerons a bit and install dual servos for the ailerons, which I did not have before. Too lazy to do it right the first time, I guess...thanks again, Bob

Jollyroger
04-30-2006, 04:26 PM
The Tiger 2 would also make a great conversion. I've seen only a couple of posts about it.

John
Here's mt T2 conversion: A beautiful flier.
Mega 22/30/3
MEC gearbox
CC Phoenix 60
UBEC
6S Lipo

rhovie
05-02-2006, 08:50 PM
Jollyroger: Nice job on the T2--how did you handle the battery placement? On the 4*40 I was able to make a battery compartment with removable hatch right behind the firewall and ahead of the windshield. Can't recall if the T2 has that kind of room. Thanks for the help, Bob

Jollyroger
05-02-2006, 11:44 PM
Bob, That's exactly what I did. It has enough room for 2- 3S 4160 Apogee packs. I am going to be using 2 3S3700 PQ in series. May even try a 7S set up as I bought these packs at Toledo from H.L. Jollyroger

rhovie
05-03-2006, 01:42 AM
Ok, and thanks for the quick reply--incidentally, I live in Sault Ste. Marie, not too far from Central Lake. Small world! Bob

Twmaster
05-12-2006, 01:40 AM
Curious 4*40 mod question. Is there any reason the 4* could not be set up for tricycle landing gear?

Dereck
05-12-2006, 02:46 AM
Curious 4*40 mod question. Is there any reason the 4* could not be set up for tricycle landing gear?

Don't see why not. As long as there's room to adequately anchor a noseleg on, or just behind the firewall - assume you'd want a steerable. The mains end up in the usual position - just enough aft of the CG so the nose drops back onto the nosewheel if you depress the tail of the model, IIRC. Mounting them in torque rod blocks a couple of rib bays out from the centre sounds about right.

It's a lot heavier set-up than a fus mounted taildragger, which is even lighter if you use a skid vice a tailwheel - which is fine for grass ops, I've found.

Apart from that, all you have to do is clear the prop you intend to use.

But that's from a guy who's had three, maybe four trike gear models since his first RC ship in 1979!

Guess I'm too tight to buy noselegs and three big wheels ;)

Regards

Dereck

Jollyroger
05-12-2006, 03:38 PM
MY older brother went to school at Lake Superior. Got his engineering degree .
I like the area, especially since you can drive a few miles out north of the Canadian side and into wilderness......maybe it's all changed since I was there. Looks like I'll have to take a short vacation "up, across" and see how it's changed.
Just a troll below the bridge.........jollyroger

rhovie
05-12-2006, 07:44 PM
Jollyroger: One of the fields I fly at is located about 15 miles north of Soo, Ont. Pretty country, up in the hills. It is usually open early, cuz it is high and dry. I have decided to hold off on doing the 4*40, and started a Tiger 2 instead. I'm planning on using an AXI 2826/10 and TP 3s2p 4200. Do you think that would be enough power? It is the combo HL sells for the T2 conversion. Also been reading the mail a little and I'm checking into Esprit Models aluminum mount. Thanks for the reply, Bob

Jollyroger
05-13-2006, 07:05 PM
The set up HL suggests is at the low end of the power scale. I checked the specs at Model Motors website and they suggest 3-5 S Lipo.Using my Ecalc, I would start with at least a 4S pack, however my favorite is with a 5S pack, a 9X8 prop which calulates to 138 W/Lb at around 38 amps,73 oz. of thrust and a pitch speed of 96 mph.A little high to be sure but the max amps are 42A/60 sec.
A 4S pack will require an 11X5.5 APCE producing 36A and 108 W/Lb.The thrust stays the same, but pitch speed is down to 53mph. This would work fine .
Just remember this is not a 3D plane, but an easy to fly low wing sportster. Mine flies great and the ROG is easy.
If I had to build one( I got the airframe from a friend) I would substitute the lite ply fuse with balsa as well as sub the lite ply formers. This would add considerable lightness to the airframe.
O hyeah, the motor mount from Esprit Models is what I used and it is a very nice motor mount. A little pricey but worth it. jollyroger

rhovie
05-16-2006, 03:03 PM
I'm thinking of adding a 2s battery in series with my TP4200, the motor is rated for 3-5 cells. I am definitely going to lighten the fuse, the lite ply is not that lite. A few lightening holes here and there will help. Thanks for the help! Bob