kahloq

We have an 800 ft paved runway. I think much of the added weight is the reinforcements I put inside the wing and fuse. Lots of wood and gorilla glue

vertical grimmace

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Maybe balance with the 3
scale technique?

kahloq

Elaborate?

glazier808

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Vic from Vic.rc makes a nice balancer for large planes. It's made from laser cut ply, and is much cheaper than other comparable balance machines.

Works great!(yes I have one)

http://www.vicrc.com/product_CGerStand.html


Casey

kahloq

Not for $85. Sig has one for $45 made of ply also

kahloq

Ok...so friend came by with a good balance stand and we got it tested. As it sits .....virtually dead on. I only need to add 1oz of lead under the forward exhaust stacks and she's good to go at 8.5" back from the wing root AGAINST the fuse. This is including the tiny fairing portion on the fuse itself.

vertical grimmace

My Feedback: (1)

Sweet! no excuses now. I'll bring camera and the cinch sacks! What time?

jimkron

Small world...I have the Vicrc one as well. It was great for building, painting, assembling, and balancing my Do335 and other big planes. Love the versatility.

Super that you only needed to add a bit of nose weight.

With my motor set-up I set my timer for 7 minutes and start thinking about landing at 6 minutes. No reason to push the lipos on a maiden unless you have trouble trimming the plane. Full flaps, plenty of speed, and a long roll-out and you should be fine.

Please take video.

Good luck,

jim

vertical grimmace

My Feedback: (1)

I will try to remember my video camera. Would really be cool to give some top cover with my FW 190 D9. I am going to guess there will not be more than one flight though as charging all those batteries in the field will be impossible. I would only want to try to form up with the Arrow on the second flight.

kahloq

I have enough chargers that I could I get the batteries recharged at the field in probably an hour and half or so....depending on how much is used on an initial flight. Im not going to try and push the flight time on the maiden if it behaves. Probably no more then 5 mins. My D9 on same motor and 12s 6000 can fly for 7-8 mins and probably more on same pitch prop, however, the D9 weighs 12 pounds LESS. The DO-335 with 12s 8000 is spinning a heavier prop and pulling a much heavier plane. The rear motor is basically not doing much and I had set the mix to a throttle limit on the rear motor for about 35-40% max since the rear motor only has a 5000 mah battery and not an 8000. However, on the maiden, since I wont be flying for longer then 5 mins, I think Im going to up the max throttle percentage to around 80% to get as much thrust as possible till I see how the plane flies at this weight.

BTW...Ill bring the Gee Bee back as well. Its ready to go again...so Ill have something to fly in between charges provided we don't need the trash can.

jimkron

Oh shoot...one more thing I forgot to mention. You might need some extra cooling.
I put a couple of holes in the firewall to force some air into the lipo battery area. It worked like a charm. Lipos never ran hot...just a tiny bit warm.


jim

kahloq

Yup....already put holes in firewall for that and also opened up the side airscoop on the inside of the fuse. Now.....I know someone is going to give me crap for this......but please just keep it to youself this time......but when balancing it yesterday......since the plane is already heavy, it didn't dawn on me that I had removed the batteries. So.....the balance yesterday was without flight packs. In a way this is good because if someone wanted to replicate my setup, they could possibly be able to get the flight batteries positioned from the big hatch behind the canopy as long as they are willing to forgo the full cockpit.
As it is, my front motors batteries will stay up front and the rear motors battery will be positioned behind the cockpit wherever it needs to go to get balance right. I will NOT have to add any dead lead. Having such a large motor up front really helps.

jimkron

No one will give you crap for forgetting...only for not RE-BALANCING with the lipos in place.

kahloq

You don't know Vertical that well...lol

vertical grimmace

My Feedback: (1)

Giving crap......it is my lot! lol I agree though, just make sure the thing is balanced.

vertical grimmace

My Feedback: (1)

Giving crap......it is my lot! lol I agree though, just make sure the thing is balanced.

kahloq

Ok....so have the balance sorted out. Here's what had to change......

1) Originally....expecting I needed nose weight, I had built the plane to accommodate the two big 6s 8000's for the 65cc rimfire up front under the "gun hood" area. The rear motor's battery would also fit there.
2) Because of the weight of the rimfire 65cc relative to say a power 160, the two 6s 8000's cannot be placed anywhere near that far forward.

3) To actually get balanced, the only battery that now goes up front under that small hatch I made is the 6s 5000 single for the rear motor. The two 6s 8000's(in series for 12s) for the front motor have to be placed smack dab right under the BIG Hatch that gives you access to the wing bolts, etc. Now the problem is, how to mount the batteries there while still having access to the wing bolt locations as the servo extension hookup for the wings retracts, ailerons, and flaps.

4) I also now have to extend the battery lead wires for the front motor's esc rearward another 8".

vertical grimmace

My Feedback: (1)

Here you go. On it's legs at the field today. Looks great. I will Let Kahloq tell the story. All I can say is, it looked the same going home as it did in the pictures.


500 server error! [:@]

kahloq

As VG mentioned, the plane made it out to the field yesterday. Initially on setting up the plane, had a servo extension from the rx battery short out and couldn't get the plane to power up. Was able to locate the bad extension and replaced it. Once everything was hooked up, the retracts were having issues extending. I had setup the power for these using a separate BEC hooked into the rear motor's battery leads. While it would power the gear intermittently, it was not at all reliable. The fault I think is that the bec simply cant push enough juice for all 3 gear to work at the same time.
Got the gear down though and had planned to do the maiden without retracting the gear anyway, but will be removing that bec and using a standard 6v nimh or LiFE pack for the retract controller box.

Got the plane out to the runway and started doing taxi tests. Everything was working ok initially on the power systems, but not long after, the rear motor started single phasing(cogging/whatever term you want to use). So...with no rear motor and having already had 2 other things not go right already.....I decided I would not try to fly the plane on front motor only. This sentiment was echoed by most at the field. While I know that the front motor has the power to do it, didn't want to take the chance that the issue with the rear motor might become worse in the air and maybe catch fire or short out the entire electrical system if the esc blows up or something. Highly unlikely, but not worth pushing things.

On the taxi tests, it was relatively easy to maintain a straight line, however, the nose steering seems a little sluggish at power. I don't think there's really a problem here, just something I need to be aware of. However, even with our 800 ft runway, this plane does NOT want to slow down much even with zero throttle. It will roll and roll and roll and one time, I had tipped the plane up trying to turn it to keep from running of the runway. It scraped a wingtip, so now I will need to out little wingtip skids on the plane. Plus....since the taxi tests weren't even at landing speeds, I believe I should investigate brakes.

RCU having issues with uploading pics again

jimkron

Good choice to sort things out before flying.
800 feet should be fine, but brakes are nice to have.

kahloq

I'm trying to see if it might be possible to have rear motor somehow reversed via a flick of a switch on radio which would then act as opposite direction thrust from forward momentum. I wouldnt need brakes then. I know thare are some full scale planes that can do this, im just not sure how to do that at an rc level of technology. Also.....it would cost me $425 to add brakes to the plane since my current wheels are not brake capable.

jimkron

How about killing the rear motor and popping a parachute? That's cheap.[>:]
I have a 17 pound Bobcat with an EDF motor. If my roll-out is going long ...I just retract the landing gear....stops within 5 feet. Yes, I've done it.
Your problem right now is not 800 feet...it's the 6 inches between your ears.
Maiden flight yips! It's good to be alive!

Enjoy the ride,

jim

kahloq

Yeah...the space between my ears right now is a huge problem...for a lot of reasons, but, without brakes or a means to slow the plane down, I will have to get a perfect approach and get it down within the first 200 feet in order to have room for it to slow down on the roll out..... every time. I am a decent flier, but, I think installing brakes or figuring out how to reverse the rear motor via the TX needs to be done as a safety precaution.

vertical grimmace

My Feedback: (1)

Isn't there a way to have a reverse or "braking" action through the ESC? I thought the RC car guys did that? Also, I thought I had heard of a slight reverse pulse to help the powered glider guys get the props to fold? Maybe something that can be programmed into the ESC? This may sound silly, but I think it is actually a good idea. The switch would have to disable the throttle funtion to the front motor and then give reverse to the rear only. Just thinking out loud.

kahloq

RC cars can go reverse because of the esc has a reverse function, but, their radiosa re set up different too electronically. Similar to a heli radio where zero throttle is actually mid stick(for a collective pitch heli where you can reverse the pitch of the rotor blades.) The problem lies in trying to program this to work in a radio that also needs to control a normal operation front motor where zero throttle is stick all the way down. Im sure someone could build a pcb board type thing that could be controlled by a switch on the tx to do what we are talking about, but I don't know of something like that existing currently. So im left with scratching my head trying to figure out a way to do this with the programming options available in most of todays 9 channel radios.

As far as the sailplane guys.......most brushless esc's have an option for braking. But...it isn't a reverse rotation, it simply stops the rotation of the motor shaft and doesn't allow the prop to free wheel. Having the shaft stop dead min its tracks is what causes folding prop blades to fold up to the nose of the plane since there's no spinning force to keep the blades extended.

Right now, Im thinking my only option is to cough up the $425 dollars for the brakes and wheels.