stumax

Greg, have you had a chance to run a 5330/5320 Axi yet? I'm wondering how they would compare to the Actro 40 for a 1/5 scale warbird. For warbirds the prop dia will have to come down and the pitch go up quite a bit from an aerobatic plane - unfortunately there are no test figures I can find that show the sort of pitch speed I'm after (70mph+). The Actro40 is lighter than the 5330, I believe, but quite a bit more expensive (but of course, you get what you pay for).

BTW, don't forget the lipo cell mfg'ers test individual cells to determine their cont/burst capability. This means that when you stack 3 or 4 cells together you'll have to back off a bit as the cells in the middle of the stack will run 30-40DegC higher core temp than the outside cells. This means that the middle cells will run down quicker than the outside ones. Not such a problem if the stack is a parallel one as the cells will self balance on resting after flight, but if it's say a 3S1P pack the middle cell will eventually die unless you rebalance each charge (and give the pack a chance to cool after flight so all the cells are the same temp)

Greg Covey

Hi Stu,

No, I haven't seen any of the AXI 53xx series motors yet. Since both the new AXI series and Actro 40 series need a higher power ESC, I expect to see Hobby Lobby address this issue soon. With either motor, you can get several different winds. If you combine this fact with the flexibility of voltage change and the prop size and pitch change, you should not have a problem fine-tuning your setup to meet your needs.

Also coming in the first quarter of 2005 with be new cell balancing packs, chargers, and support products like the "Cell Pro" from FMA Direct. FMA has also released a new flight data recorder and will have measuring devices for measuring current, voltage, RPMs, elevation, and air speed while in flight for up to 90 minutes. The new 3.2AH cells are released and soon the unitized packs from Eagle Picher.

All these items will be addressed in my second part of this conversion adventure. Once the 1/3 scale bird is running for a full flight, we'll also give it a full series of aerobatic and 3D flying tests on video.

Henke Torphammar

Has the 90-O Arrived yet? =)

BiplaneCrasher

Greg,

i have been reading on your post here about the conversion. I dont mean to detract from your project, but you seen to be in the "know". I wish to take a plane like the Sig Sundancer (3.2)50cc) and electrify it. Little planes dont do it for me anymore. The 50cc size gives plenty of room to work about the fuse and hey! you can actualy see the plane flying in the sky. I cant swing the 500 bucks for the Actro 60, but I can do the Axi 5 series based on a recomendation from a member here on RCU.

I was thinking an Axi 5330-18 with 32 NiMHi cells with the 90-0. I should have ample power for decent hovering and aerobatics I think...How many cells and what prop would be most desireable?

Whats your opinion, we'd like to know.

Ed

red_z06

My Feedback: (11)

Biplane:

1 set of 32cell nimh 3300mah + Axi 5330/18 will weigh around 5.5lb.
50cc engine + muffler + 2 batt + 16oz fuel will weigh around 5-6lb.

That means the slow/stall performance will be comparable. However (assuming your nimh cells can handle sustained 90A current draw), your full speed flight time will be limited to:

Flight Time (min) = Capacity (Amin) / Current Draw (A) = 3.3Ah * (60min/h) / 90A = 2.2min

If you do 1/2 throttle flying, you may get 4-5min flying time max.

This is less that 1/3 of flying time with 14oz of gas flying with 50cc.

If you do 2 parallel set of 32cell nimh, you will get 8-10min flying time but you will tack on another 4lbs or increase your AUW by 20%. Your plane will no longer fly the same.

If you went with the Lipo setup(currently no lipo single cell can handle 90A), you will need 9S* 2p or3p depending on cell choice.
Kokam 15c 2000mah cells will handle 30A so you need 3p (3 in parallel) configuration and endup with 6.0Ah or 4min full throttle flying.
The 3cell pack weigh 6.5oz so you will end up with 9 of these or 3.7lb which weigh comparable to 32cell nimh.
It will cost you $70*9 = $630 for a set.

Kokam 20c 3200mah cells will handle 64A so you need 2p and get 6.4ah or 4.3min flying time at full throttle.
The 3cell weigh 10oz each so you will need 6 of these at 3.75lb.
It will cost you $130*6 = $780 for a set at Tower prices.

If you need max 90A then you can go with 9s3p pack as it is more cost effective. But if you need more than 90A up to 120A then go with 20c pack.
If you go with 10s2p or 10s3p you will get 10% more performance. Just add 10% to all the figures including price.

I like to stay with all 3 cell packs or all 2cell packs for ease of balancing packs at the field for rechage using parallel charge method.
In order to use 10s config you will need 2 3s packs and 2 2s packs.

Greg Covey

Hi Ed,

Sorry for the delay. I was traveling and lost site of this thread.

Your plan sounds very reasonable. I would stick to a 32 cell count with the 90-O-Acro ESC and start with a 20x11 prop. APC makes this 20" prop in several different pitches and the 11" pitch is a good middle starting point.

Ahhh, I see the next post now and it looks like Red_z06 provides some good information.

You may want to start with using some GP3300mAh NiMH cells and see how you like the performance. My assumption here is that you will not likely need a 90amp draw for more than a short burst. Recall that my 20lb Edge 540 flew well at half throttle.

Good luck!

locoworks

one third the cost?? i dont really think so, zdz 80 single and a can plus usual batteries + petrol running costs versus big brushless motor with controller plus enough lipo's ( at least 3 full sets ) and an array of chargers to charge them at the field to keep you in the air.... i don't think so. if you go nicads or nimh it may be cheaper than gas but you still need a boot full of battery packs and chargers to suit but your flight times would be reduced somewhat.. either way i dont think 1/3rd the cost pans out. if you used a DA 100 and all the bling electronics you could use maybe, but the performance with the electrics you actually used is not comparable to gas. hell, a big rubber band would get it airbourne. don't get me wrong, i like the idea, but i think 1/3rd the cost is misleadsing.

Norm-RCU

Locoworks, he's not comparing the costs to gas, but to the other large electric powered planes of this size where they are using 2 or more motors, controllers, and battery packs.

locoworks

OH, i thought from the headline and the not unlimited / spectacular vertical in the review comment it was compared to gas, i take it all back then, sorry folks. i'll leave the post in to demonstrate my misunderstanding. it is in the glow to electric section afterall, not a to be created ' already electric to 1/3 the cost electric' section. DOH..