Extra 260 is ready for its maiden! It weighs 10lb 8oz dry and 15lb even with 2x 2lb 4oz batt packs.

couple more pics.

Notice the total lack of cutouts on the cowl.

OK!

After working all day to finish the battery box and change 3.5mm bullet ESC connectors to Feigao 4mm, it finally flew.

The flight time is about 10min with battery reserve ( landing voltage per 3cell pack was st 11.2v ). It will hover about 1/2 throttle and it has unlimited vertical. IMO it tracks much much better than my DA50 powered PW extra. It does awesome flat flat inverted spins and quite acceptable flat spins. The plane is too new to wring it out so more test will come.

I am waiting for better prop for this plane (22x10, 22x12) as 20x13 makes it too fast and not enough thrust. I also feel the need to build a louver in the cowl inlet to direct air to motor drum.

I have not so perfect maiden vidoe. Those who would like to see say "I"

I
I
I

Well, I'll try this again. I just wrote a long write up on mine then apparently lost it before posting.

I just found this thread as I don't monitor 3D forums. I'm mostly interested in precision aerobatics. I have 5 flights on mine.

My power system is:
Actro 40-5 with Actronic 32-70 controller
APC-E 20x8 prop
10s2p 4000 mah Thunder Power ProLite pack
11 oz. 2600 mah Rx pack, (I need the nose weight).
RTF weight is 13 lbs.

The paper tube houses the controller and directs prop blast over it.

Norm

Thanks for the conversion info! I have been watching this one and am interested in doing a larger scale electric than my 60" Giles 202/ Axi 4130/16.

Keep up the good work Red z06!

Norm, Awall - Welcome to the thread!

Norm - My ESC shutdown on 5th flight causing water landing. The ESC shown on the side of the motor box will be slanted and be flush with bottom of the cowl exposed.

Here is a link to my extra 260 video

http://www.bsc-engineering-usa.com/E...2005-06-11.wmv



wait 30min as it is still being uploaded.

Nice video and great flying, thanks for sharing. Have you done any precision IMAC type maneuvers with it? If so, how'd it do? Mine had some wing twist and misalignment but I'm working on it.

sorry to hear about your ESC shut down. How many amps are you actually drawing at WOT?

Norm

nice vid.

So when you do water landing, is the battery a loss? Won't they short circuit?

Norm - I estimate ( need 2 whatt meters in parallel to get full current as one is limited to 70A ) about 90-100A at full throttle with 22x10e prop

BoneDoc.

Batt ok.
ESC ok.
Receiver ok.
Hitec HSR5955TG servo ok - it had 3 o-ring around the case and each screw had its own o-ring.

casualty

1 Hitec 5625 servo
1 nicely painted cowl
bottom covering torn ( pearl blue covering )


As soon as I elevate the ESC to bottom cowl surface, it will be flown again. I hope the eprop get here b4 that.

Temporary location of the esc on busted cowl. Although it was only temporary, it does not look too bad. What do you think?

It also shows the inlet louver. I will eventually build a concentric ring around the motor to complete the ventury.

Red,
I would mount the ESC just like you have it, but on the bottom of the cowl.

I have a question though. It looks like in the middle photo above you blocked the airflow. I am missing the point of this. You need as much airflow across the motor and batteries as you can get. Especially since you are running such high amps. You exit hole must be twice the size of the entry hole to creat a vacume effect to force cool air in and warm air out.

Thanks for sharing the conversion. I have followed Norm's, but it is good to see another.

-Mike

Mike:

Yes. top esc is only temporary as I am lazy too build a standoff at an angle to make the esc flush to bottom.


Open cowl will give higest flowrate but least will actually reach the surface of the motor as air stream will look for least resistant path. It is most beneficial to batt as the coolest air gets to batt. However, I'm not too concerned about the batt temp as I'm not pushing the batt too hard. 10min flight on 8000mah means the average current draw is 480ampmin/10min = 48amps or about 6C. It only gets warm which is also good for longevity of the pack.

As you put the baffle or louver, you are forcing the air to pass near the motor surface reducing the boundary layer thickness. You are reducing the Q (flowrate)

but improve the airflow near the motor. Combination of Fluid Dynamics and Heat Transfer at work.

The motor temp has been reduced but the esc temp has gone up before the esc relocation. To improve the system, concentric cylinder needs to be constructed around the motor so air does not escape to area on top and bottom where there is least restriction as is the case of current louver setup. Only expement will tell what the optimum gap between the ventury cylinder to motor can diameter should be.

I really need a separate cool air inlet from the motor air as it is already heated.

My suggestion, since you already cut the cowl on top, is to paint the heatsink blue, that way it'll match. From 10' away, no one will notice the difference anyway .

Nice video! I think I kinda follow you on the whole airflow thing. I know nothing about the physics behind optimizing airflow around things inside the plane... but if it works, do it! Sorry to hear about the wet landing.

What do you think the whole conversion cost you total? Just interested on how much money to set aside for my project!

I agree that you want baffle air and direct it over the components, the photo (it may be deceiving) look as though the entire front is baffled with very little space for direct airflow on the batteries. Of course if they are staying cool, it is working. I had to design in an airscoop to keep the packs cool and small deflector baffles reside in the cowl to deflect air around the motor.

Again,
Great job and good video. Looks like you have a winner!

-Mike

Mike:

fresher air is better than heated air exiting the motor. I may endup adding a scoop on the bottom for flow into the batt chamber similar to your yak.
Ideally you want fresh air into the baffle and exit to side before entering fuse. same for esc and batt.

I wish i have the eagle tree telemetry system while i work out all this.
For now, I have to resort to finger method and duratrax thermometer. I believe the thermometer can be left on for continuous reading of max temp. it might be useful.



awall:

aside from the usual stuff ( servo, receiver );

Axi 5330/18 $250
Jeti 90 opto $250
Ubec 6v $36
2 9s2p Kokam 15c 2000mah cell pack $450x2 $900 --- I would steer you away from 20c pack as they will run harder and longevity could be an issue.
alu mount $30
custom cable $15-$20 in material



I think I coverd it all.

3 people reported having problems in grass so far.

please vote on cf gear problem / no problem on my poll



here is the link to thread

http://www.rcuniverse.com/forum/m_30...tm.htm#3076335

is the 4p just for the extra flight time or do you need it to keep up with the motor? I was thinking about using the same motor on the same plane but use tanic 9s2p 2500 (12c) that would be a 60amp constent so will this work?

My flight time is about 10min and I only put enough batt for the current draw. I need 2 whatt meters in parallel to check the current above 70a but i expect around 90-100a at full throttle. You can setup to draw max of 60a. You will prob use 20x10 prop to achieve that. If you want to hover at 1/2 throttle you will need to use 22x10e prop. 20x13e will work too but too fast and not enough thrust.

At 90amps 4p (8000mah) should last about 5min full throttle.


My funtana 90 uses 9s2p (4000mah) with axi 5320/28 and I get about 10min flying time.

Maby a 21X14 will give just above 1/2 throttle hovers but less amps, but then again the extra pitch might give it more amps?

anytime you want more thrust you want to increase the diameter at the same time reduce pitch. This will slow you down but you get the maximum thrust without much loss. smaller diameter ( no matter the pitch ) will always draw more current at given thrust but always more speed.

Dude your like a walking electric dictonary, I kinda had an idea but was confused. Now pricing everything out it looks like for a first larger electric the funtana 90 with a 5320/28 looks like a good solution. then always from there you could upgrade to the larger plane and share the packs. I was diciding between the funtana and this even befor i saw the thread and well this has made me make up my mind.

Thanks for the help!

You will get good performance to energy density from a 15c ( continuous ) packs. When building your pack add multiples of packs until you reach matching discharge rate. For example 15c (2000mah) pack will pull 30a so you need 2p. You need to convert mah to Amin. So 4000mah will be 4ah or 240amin.

Then you divide by full throttle amp or 60A. 240amin/60a = 4min That means if you pull 60a continuous on 4000mah 15c pack you will get 4min of flying time.
If this setup is for 3d flying with 1/2 throttle hover, you can get between 2-3x that with good throttle management or 8-12min.

20c packs on the other hand gives you good performance but not enough energy if you match based on current draw. For example, new kokam 20c 3200mah willl pull 64a continuous so you can get by 1p setup but at 60a you will get little over 3min at full throttle. Not enough in my opinion. If you double up on 20c pack it defeats the purpose of using 20c packs.

go with Kokam 15c 2000mah packs

sorry about kinda hyjacking the thread[]

Yeah the tanics are 2500 12c and i would go 2p so thats 6s2p for 5000mah so thats 5ah or 300amin (5ahx60min) then 300/60=5min. The only reason that im going for the tanics is because I can get them easyer. Very nice equation!

Also for the esc a CC80 should be good right?

Oh about the whole electric price thing, you forgot about the windex and papertowel in the total prices