88" Extreme-Flight Yak Electrified Build

[Lokiyawl]

Simpleton, Thanks for suggesting the EF Extra thread, I actually found it earlier and there is some good information there. James

[Lokiyawl]

Richard,

I responded to your very helpful email but I don't see it on the board so I am posting again. Thanks for you input
on the Hacker and the 99 AMP ESC setup. I am running the same ESC in my 74" and with the Plettenberg EVO and I have a bit over a 2:1 power to weight ratio and maybe 1.8:1 with the Eflite Power 160 which is heavier but has been 100% reliable. I would be nervous having so little reserve power while hovering down low and having an ESC shut down. I have done hovers exceeding 3 minutes with these setups with no shutdowns and only a very mild temp rise on the ESC, motor and batteries, 400+ flights and not one problem..electric can be wonderful!

Having an ESC shutodwn from time to time would pretty well eliminate the advantages of going to electric to start with for me. I try to size my ESC's so that they are a good bit larger than the max expected amp draw. It costs more in weight and $$ but I think that it is worth it for a plane that is important to you. I would like to try and come up with a setup for the 88" Yak that would meet the following criteria:
1. Have at least a 2:1 thrust to weight ratio
2. Be able to utilize my existing 3850-5350 5S batteries.
3. Have flight times of at least 7-8 minutes which is what I am getting with my 74" Yak.
4. Not be excessively heavy. ( I think that to get 8 minutes that I will be a good pound heavier than a light DA setup on the 88" Yak)

The Plettenberg on 14S seems like it might meet these requirements and exceed the thrust to weight ratio by a good margin. The cost of that motor is a concern of course and I wonder how the effeciency will be at the higher RPMS. Has anyone else run the Pletty on 14S and have any feedback on flight times? I think that the EF 88" Yak is an epic plane and would love to have a really nice electric setup in one. If anyone has any thoughts or ideas let me know. EF is currently out of the Yellow and Black color scheme so I have time to research this...
Thanks, James

[Captain Carlton]

James,

Yah...the power reserves with 12S-5000 and the hacker...are really bad....for what we do anyway. I think 12S-5000 will work itself...with healthy batteries...and with 120AMP+ ESC. Ideally...you going to want a reliable 5000 watts of juice on hot standby.

For what it is worth, I am flying a 26-29lbs QQ Yak 102 with 14S-5000 or 14S-10000...with a Schulty ESC...and NEU power. A real nice setup!!! 28x20 prop...and about 7100 watts. Sweet ride.

But like I said...I am still unkinking my 50cc birds.

- Richard

[can773]

	Quote: Originally Posted by Lokiyawl
	Chad, Thanks for your input. I just got confirmation from Plettenberg that the Terminator can be run safely on 14S with bursts of just a few seconds to 120 AMPS. That could yield 6300+ watts which should be gobs of power. The interest in the 14S is to allow the use of my stash of 5S 5000 packs. Add a 4S in series and I have upped my battery power by 40% and the 88" Yak is about the same percentage heavier than my 74" Yak so I am hoping for similar flight times. The downside of the 14S is the smaller prop, about 22" but then I believe that is about what is used on the DA. Let me know what you think of my idea, I am just in the planning stages at this time. Thanks, James

Hi James

If Pletty said 14s was acceptable then go for it! I do know guys have pushed that motor to 6kW, and it can probably do more as long as its not getting hot. I have ran the Evo to 4kW and its a much smaller motor.

I would try and keep as much diameter as possible on the prop, and reduce the pitch to keep your peak amps reasonable. With the higher voltage you will have lots of rpm, so you should be able to get away with less pitch than what someone running a 12s setup would have (12" usually). Probably a 22x12 would be a good start point...you are have about 35-40% more rpm than an Evo so based on that I would guess you will be in the 110-115A range on that prop with 14s. Then maybe try a 24x10 and see if you could run that, you might find you still have lots of available speed, but better pull out of it.

Chad

[Lokiyawl]

Chad,

Wow, that was really helpful, thanks! That is a good idea I think to try and maximize the prop diameter to keep the thrust up, I will take your advice. Pulling power is more important than speed (pitch) to the kind of flying I am doing. The only disadvantage I have noticed is that very large diamters seem to make hovering more difficult due to an increase in torque. Maybe it is just me but I seem to run out of ailerons trying to hold the prop torque in a hover on my 74" with full bevel to bevel throws, have you noticed this? I should also mention that with my EVO that my MAH per minute dropped a good 15% when I went from a 21" x 13" to a 22" x 12" which gave me a full extra minute of flight time. I thought it was just a glitch at first but 10 more flights have all shown the same improvement. The thrust is also better with the 22" and the WOT static amp draw is higher of course.

Can you comment on how you feel that the 88" Yak would fly on 6000 + watts using either of the props you suggested? And do you feel that I am on the right track with using the Terminator or should I be looking at other motors for this plane? A few people seem to have good feedback using the Neu motor on this plane with 12S though the flight times seem to be really short (about 6 minutes) using 5000 MAH. Do you think that 7- 8 minutes would be possible with this plane without getting too heavy? I am getting 7-9 minutes ( batteries from 3850-5350 MAH) and leaving 30% in my batteries with my 74" and just wonder if there is a reason that this can't be done with the 88"? I have been reading these boards for a while and have come to respect your, so thanks again for the help with this project.

James

[JagerBomb]

You know guys, I have watched where this thread has gone and I'm really surprised. I have run the Hacker A60-18L, Spin99, with Flightpower 12s 4900 25c batteries for two years and over 450 flights without a single thermal event. I fly aggresive 3D all the time and have beat this package unmercifully. I don't pull 20 second long uplines but I do put her right on the deck. You might want to rethink your setup or flying styles to fit the advantages of the light weight.

[cjdscratch]

	Quote: Originally Posted by JagerBomb
	You know guys, I have watched where this thread has gone and I'm really surprised. I have run the Hacker A60-18L, Spin99, with Flightpower 12s 4900 25c batteries for two years and over 450 flights without a single thermal event. I fly aggresive 3D all the time and have beat this package unmercifully. I don't pull 20 second long uplines but I do put her right on the deck. You might want to rethink your setup or flying styles to fit the advantages of the light weight.

I was really suprised also after reading this thread a few days ago. I too have been running this same setup in my 3DHobbyshop 89" Slick with a APC 25x12.5 E prop. I have had zero issues and it has plenty of power at 18.5lbs AUW. 4000 watts = 216 watts per pound and 5.3 hp........

[Captain Carlton]

Mark,

The lightest the plane gets is about 18lbs even ... with going to more carbon. I thought the issue was mine alone, but I have two identical setups....that I followed here...and these planes thermal out...no doubt. I have seen it in both of mine, plus Matt Stingers Plane. Maybe there are variations in these speed controls. Below are photos from Bakersfield IMAC Free Style. Matt Stringer is a fantastic pilot...but these are photos of his plane thermaling out...and getting him last place...one minute into the event. Bottom right is an ugly dead-stick. He did a bit of damage. The issues are not isolated or rare.

I have moved my ESC down to the bottom box for cooling. However, I have had this plane previously thermal on me probably 8 times...and I don't trust it anymore at all. I have cleared it for use by my 10 year old to fly it for IMAC sequences...but low 3D is banned with the config.

The ESC needs to be higher amp draw...down in cowl box. Its not an airframe issue, but clearly the components are being used by us too hard...too close to the edge. Just our experience out here in the west. If I was buying new for this plane, there no way in hell I would use that ESC. The motor is marginal on power...as has been discussed at great length in a build forum for the Electric AJ Slick 89" at RC Groups. In fact, of all the motor options...it just about the least powerful. I want people to understand this up front if they are throwing down their hard earned cash.

- Richard Carlton

[Lokiyawl]

Mark,

You mentioned the use of carbon to get the plane down to 18 lbs. I am assuming that you are changing out the main gear but is there anything else? I would like to suggest one easy way to save perhaps 2 ounces on at least some EF planes. The hinges really long, in fact about 2/3 of the barbed end sticks inside the wing and is usually also coated with a lot of epoxy or polyurathene glue adding even more weight. I have been cutting my hinges so that they just protrude through the back of the wood. I also sand the hinges to roughen the surface then acetone for a better bond.

I own two of the Hacker 99's that I use in my 74" Yaks and they have been flawless. It really does however sound like they are just not enough for your particular setup. It is interesing that Mike has not had any problems with his setup after 450 flights but maybe the temps in your area are just a little warmer and his setup is on the edge but has not gone over it yet. Certainly I want to have a good reliable setup and I like having good power for the pull out. Weight wise I don't think that the 14S will come in that heavy. If I were to run TP Prolites, the batteries would weigh 1,684 grams (2-5S at 602 grams, 1 -4-S at 480 grams) versus 1,432 grams for the 12S setup in Prolites. If I ran Zippy 5000 MAH packs in 12S the weight would be 836 grams x 2 = 1,672 grams or a whopping 7 grams lighter than a 14S setup in the Pro Lites. The prop will be a little lighter since it will be smaller too. (grin) I really don't think that the 14S setup has to be heavy at all and with throttle management should give 15% longer flight times. Realistically I don't think that I can even feel a 5% increase in the weight of a plane and that would be almost a pound in this case. How much does a smoke system weigh or pipes? If anyone has an opinion on the best flying weight for the 88" Yak please let me know while i am in the design phase of this project! Thanks, James

[Lokiyawl]

Richard, Wow, that is a big electric setup. Can you hover this plane? How are your flight times? And I notice that you either run 5000 MAH or 10,000 MAH? Would that be a doubling of your battery weight? Thanks, James

[Lokiyawl]

Jagerbomb, So if you are getting 4,000 watts then you are drawing close to 90 amps WOT? Hmm, that should be 10% below the max on the ESC. Really glad to hear that this setup is working for you. James

[Lokiyawl]

Mark, That is a great shot of your 88" hovering, nice! How are your flight times with the 4900 12S? I am trying to keep an open mind here on which way I should go. Using Prolites, my proposed 14S setup would come in 252 grams heavier than a 12S 5000 MAH 12S setup so not that much of a difference. I was looking at the Zippy batteries because of price and they are a lot heavier, in fact the ProLite 14S setup would be virtually the same weight as a Zippy 12S setup. If you are happy with 4000 watts, then 6000+ ought to be a lot of fun I am thinking. (grin) Thanks for the input. James