David,

I cannot help you with your electrics, sorry,

but I would really like to know about your 5-blade prop.

Charles

Yes, that's excessive.  Going on the rule of thumb that a stunt plane uses about 7W/ounce, you should have about 15% left at the end of a 6-minute flight.

The first thing I'd suggest doing is trying an APC 13x5 2-blade prop and maybe an APC 13x6 2-blade.  If one or the other works just grand, then you know that your prop is causing problems and you can decide if you want to compromise on more battery or more prop.

I can help with the setup but am also curious about that prop, sounds like it might be an amp eater If its 13 inches and 5 blades it is most likely too much prop. On a "normal prop" that rimfire 32  is more of a 5s motor at 800KV . The eflite 32 is also more of a 5s motor too so you wont see much difference. We are running 11 and 12 inch 3 blade props on those motors or similar or 12 or 13 2 blade props. Your castle 50 amp should be fine. Lots of us including myself are running 6s batteries in similar planes. You could go to a 6s or stay with the 4s 4000 which should also be fine. Do you have a preference? If you do I can help you match the motor and prop to the battery.

Thanks William, but about how many mah?

FWIW, the rule of thumb is that with a constant motor speed setup (Hubin + helicopter mode, or KR), then you'll use about 7 watts per ounce of plane weight.  Randy's numbers match that pretty close -- your numbers are horrible; using that rule of thumb you should have 42% battery left after a four minute flight.

I use an XOAR 12X6 2B with great success on a similar size motor.

Many use 6s 2700 - 2800's.  I use 6s 2700 for a 12 x 5 prop, or 11 x 5 3 blade, but then about 700 - 750 Kv on the motor.  I found that 5s was always near the 20% low limit with 5 cells, and below the limit as cells age and capacity is lost.

I'm using the Thunderpower 6s 2800 with the Cobra 3515/18 740 kv motor. . I have the Igor 12 inch 3 blade prop. I'm landing with 27% remaining in my battery. Anything similar to that or like Fred or Tim posted should work fine. If clearance is a problem why don't you either use larger wheels or make a longer landing gear. once you get everything matched up i'm sure you wont have capacity problems. If that motor was crashed I would probably replace the bearings and possibly the shaft. If you have another motor, just replace it and compare.

But the real bottom line is that the way to successfully fly electric stunt, unless you're really experienced is to shamelessly copy something that works.  That means don't do the math, don't even think about doing the math, just look on the "List Your Setup" thread, find a similar-weight plane, and do what they did.

I have been saying this for the last 10 years!!!!!! Tim you just said it perfectly!!! There isn't anything to figure out anymore.

William,

Could you please tell me the weight of this model?

Charles

62 ounces but similar setups have pulled planes as heavy as 72-73 ounces. My SV22 was about 72 ounces with a similar set up. My Voltron was about 64-66 ounces depending on the set up I had in it and how I had it configured.

Okay, guys, so I did some quasi-scientific experiments on efficiency. Here's my method. Run the motor for a minute. Measure the pre run and post run percentages and take the difference as a better than nothing measurement of efficiency. All batteries were zippy 4s 2700s, no I won't be using them, but they are all about the same for my test.

Rimfire 32 with my 10x8 5 blade prop - 35% pack consumption in 1 minute. - this was the nightmare consumption I need to avoid.
Rimfire 32 with a 12x6E apc (I will not have clearance for this prop unfortunately) - 30% consumption - and a ton more thrust.
eflite 25 with 12x6E apc - 29% consumption
eflite 25 with Bolly 9.5x6.5 4B - 30% consumption and slightly less thrust, but possibly adequate--hopefully.
eflite 32 with Bolly 9.5x6.5 4B - 22% consumption.   22%/minute x5.5 minutes = 121% of a 2700=3267mah on 4s. Not too exact, but my 4000 should cover the need, and switching to 5s or 6s, who knows, but probably will work out... Eflite 32 is .4oz lighter than rimfire also. Eflite 32 should work great with the lower consumption.
At this moment I have a combination to go forward with because the Bolly also clears the ground.
I'll think I'll try one more time with a MAS 10x7 3blade I have lying around. Update. Mas 10*7 3b used 23%. Also pretty good. Hard to tell tell it's in the air.

Question, does anyone have a spare Bolly 9.5x6.5 4B I could buy?

Did the Master Airscrew 10x7 3 blade have enough "pull" in the maneuvers for that heavy plane?  Sure used a lot less battery in your experiment.

Yep, agree with William.

If the plane is for flying the pattern then give yourself every advantage and change the gear.  Is the design and look more important?  The problem bigger than battery usage is having a prop that flies the plane well.  I have had best flying with Igor props, but Xoar 12 x 5 2 blade electric prop is more than adequate.  Then 6s battery, about 10,700+ rpm and about 69+ feet radius for a heavy and full size plane.

I'm sure that the prop is the problem.  Prop efficiency varies widely, and it takes some science to make a good one.  It is difficult to make an efficient 5-blade prop, and even more difficult to make an efficient 10" 5-blade prop.  No, your 10" 5-blade prop is not equivalent to a 13" prop.  A ground test won't tell you anything unless it's in a wind tunnel.  Don't believe any online calculator except Javaprop. 

I have Impacts of about the same weight.  I have been flying one powered by an E-flite 32 with a 2800 maH 6-cell battery, which has about the same energy as your 4000 4-cell.  It's plenty. 

The most efficient props I've used are the APC 13-something and a carbon copy of it. Next most efficient are Igor's. I'm currently using Igor's 11". 

It sounds like you were doing these tests on the ground -- yes?

Unfortunately, that's only a very rough measure of power consumption.  Props unload considerably in the air, and electric setups insist on driving the prop at a constant speed.  Moreover, low-pitch props will unload more than high-pitch props.

I think you should at least try longer gear -- I'm not sure what your "unusual setup" is, but you say its an Impact, so it should look quite natural with an inch more in the landing gear.

Yes, I did the tests on the ground. When the temps drop below a 100 outside I'll do some air tests. I'm nervous to buy packs until I know what I'll need. Sounds like 5s 2700 is popular.

The prop is the problem. Make changes and get more clearance so you can use an appropriate prop, otherwise you’ll be banging your head on the wall.

Here's a tiny bit of math, for reference:  To compare the energy in two packs, multiply the cell count by the mAh number.  So (5s)(2700) = 13500, and (4s)(4000) = 16000.  But please don't start calling that by some name.  If you want named energy units, turn it into Joules by multiplying everything out -- cells * (3.7V/cell) * (capacity in mAh) * (1A/1000mA) = energy in watt-hours.  So your 5S, 2700mAh pack has about 50 watt-hours, and your 4S, 4000mAh pack has about 59 watt-hours.

(Yes, to be totally metric I should take things out to Joules -- but if you round up a bit a flight is 6 minutes, or 0.1 hours -- if you calculate the battery energy in watt-hours, you just multiply by ten to get the available average power).

Okay, thanks. I'll probably suck it up and redo my gears, darn, even had those cool wheel pants on them. But I also discovered when I put my motor back in that the rimfire was just barely touching the edge of the motor ring. I probably noticed it when I was putting it together and thought, I'll get back and fix that before I fly it...and then I forgot about it. I think that was my main problem with run. I'm only set at 80% with the 10x8 so perhaps kicking it into the 90% range the Bolly or MAS will work.  Hopefully tomorrow I'll have some in air tests with the other props. Yes, I'm not redoing he gear until I know for certain that I'm screwed. But I did remove an ounce of weight in the process of it all, so, there's that.