F27b Brushless Upgrade

[gavj8]

F27 Mods

Just completed a build for a friend on his F27b. He purchased a bare airframe from SL and asked me to equip it with brushless etc using the rx from his spit. Mods to date are:-

1. Fit carbon spar to strengthen wing area
2. Manufacture and install new motor mount
3. Fit brushless outrunner motor, esc and receiver


For the carbon spar, I used 4mm carbon rod cut just short of the aerial channel and using a soldering iron, very carefully melted a trench deep enough to fully conceal the rod. Fix the rod in place with hot glue.

Ditch the flimsy motor mount - Heard about these breaking and even snapping the foam clean off in crash. Decided to go with something a bit more substantial that could handle the extra power from the brushless motor. Using a Stanley blade, remove the foam hump from the top and bottom at the rear of the back canopy to give a nice flat surface. I decided to use 1/16th ply top and bottom, epoxy’d in place for the mount. The shape of the ply top and bottom are different and have rounded shape to prevent manufacturing a shear point for the foam to break (see pics) in the event of a crash.

Used an aluminium motor mount screwed to the ply with the supplied self tappers.
Found here:- http://www.brchobbies.co.uk/?page=shop&action=additem&item=636

Mounted a 2200kv brushless outrunner motor found here:- http://www.giantcod.co.uk/product_info.php?products_id=402397&osCsid=58802484efb01b3aa85b9ebd4300f401

Used a 40a esc found here:-
http://www.giantcod.co.uk/product_info.php?products_id=42&osCsid=58802484efb01b3aa85b9ebd4300f401

Had to modify the receiver bay to get the receiver and speed controller to fit.

To get the correct centre of gravity, fit a lipo battery (im using a 2400mah 3s) as far forward in the battery bay as possible. This means having to cut a section of the bay away allowing the battery to go to up against the back of the nose cone (see pic).

Im using a 5.5 x 4.5 APC prop and initial bench testing indicates this thing should be like a rocket!
Were hoping for a test flight as soon as the wind permits.

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[gavj8]

More pics

Forgot to mention, also drilled some 10mm holes through ply motor mount to reduce weight.

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[Radweld]

I would not want to fly that on the 27Mhz system out of a Spitfire. The risk of being shot down by some kid and his Argos toy is too great. That bird needs a Spektrum system.

When mine crashed it snapped the foam off, I glued it back on and used thicker Vinyl covering instead of the thin sticker. The Stryker C mount is larger so spreads the weight better.

Nice mods though.

[gavj8]

His budget hasnt stretched to a dx6i yet (nor mine for that matter!) . The good thing where we live (in the sticks) is that there are no other models. In fact in all the times weve been out, weve never seen another plane/heli/car to date. Thats not to say we wont get caught out one day, but for now.... the mrs thinks 27mhz is just fine!!

[ralphp]

LOL....shot down by Argo's.....best I've heard all week! I had it happen to me when I was flying gliders......it was a five year old with a toy truck! all I can remeber thinking at the time was "whats a kid with a remote control truck doing on a golf course?"......Im sure it was a dwarf golfer in disguise! rats!

[gavj8]

Yeah i know its not the best and range has also been an issue (guess how i found out!) Good news is Friday afternoon is looking promising weather wise so should get its maiden flight.

[Radweld]

I've been using a KMS 2000kv in runner using the stock motor mount and its gone ok, I'm going to re-paint mine, I just ordered some fluorescent Green, Yellow and Orange paints lol I think I will be able to see it better then.

[ralphp]

you think?????LOL!!! Top gun hear we go! whats next wide wheels and exhausts!:D
Dose this match the living room?
you really make my day mate!

[Radweld]

Actually I've just been looing at the fuse to see if it's possible to install retracts lol.

No, stop it. Finish my other projects first lol.

[Radweld]

I want more power now! maybe a 300kv motor will do.

[gavj8]

The set ups are endless for this thing. After finishing my freinds build (still waiting for decent weather up here to maiden her) I decided to buy a bare bones unpainted airframe and add another PZ model to the collection! Just finshed it last night.... same set up as the one above except fully glassed (3/4 oz cloth and Poly-C) and this ones going to be 4S.
What do you think the optimum motor size / prop size would be?

[Radweld]

Well glassed means the AUW goes up a bit, you need more power just to keep it in the air. The Styker C uses 1800KV motor and about a 6x4. I'm using a 2066KV motor and a 6x4 and performance is ok, just not stella. Im thinking a motor in the region of 3000kv (about 30amp draw) and what ever prop is suggested, probably similar in size to what i'm using now.

[gavj8]

Just got in from my maiden flight and all i can say is Wow!! First attempt was lifting the nose on 3/4 to full throttle so placed a small washer under the front (prop end) of the motor mount. This worked great and kept the nose level even at full throttle. It was a tad windy (7-10mph) but it flew like a dream. I reckon around 70 - 80 mph top end and coming out of a dive must have been close to 90mph. Acrobatics are a breeze and it does axial roles like it was on a bbq spit. Very very impressed. The carbon spar and glass cloth held everything together even in the tightest of turns/loops. Landings are so easy too. Fly her into the wind with the throttle off and it basically hangs there in mid air! Only trouble now is I want more speed!!!

I would highly recommend this model to anyone wanting to move on from the warbirds. And if you are unfotunate to crash, a bit of gorrila glue and your up and running in no time. Flew four full lipo packs with no mishaps. Well made up! Makes a change from doing major surgery to the P51!! :D

[gavj8]

Well after a dozen or so successful flights, I couldnt resist the need for speed any longer and swapped the motor. I have now fitted the AON 3000kv inrunner from my P51. Just waiting for two new props to come as the 6 x 4 would pull way too many amps.

Found a great little online calculator for estimating amp draw and flight time with different motor/prop set ups. http://brantuas.com/ezcalc/dma1.asp If your battery / motor isnt in the list then just select custom and fill the boxes in yourself.

The 3000kv motor with a 5 x 5 prop is showing 117mph prop pitch speed with 37 oz of thrust (AUW on my glassed F27 is 26oz). So should be pretty good!

Test flight report to follow.