Dick Sarpolus' Akro

Designed by Dick Sarpolus. Free plans from Winter 2014 Park Pilot.

The Akro can be built quickly and easily, and for a truly low cost. The model flies well, it’s big enough to handle some wind, and it’s great for basic aerobatics. If you’re past the basic trainer stage, I’d suggest it as an airplane you could use to learn how to do all that aerobatic stuff. If the stress level felt while flying is proportional to the cost of the airplane, you can relax in the knowledge that the basic materials cost of the airplane was less than $10. So, hey! Even if you fly it into the ground, it can usually be fixed with five-minute epoxy. You can’t feel that bad if you crash an airplane that’s so inexpensive and easy to build. This Akro has a 38-inch wingspan with roughly 330 square inches of area. It’s 32 inches long and weighs approximately 12 ounces without the battery. Any 100-150-watt brushless motor will be fine, and opt toward the higher number if you want to fly the crazy stuff. Any 3S LiPo battery from 1300-2200mAh will do the job, depending on how wild and how long you want to fly. The main goal for this project was to give you an easily built, truly low-cost flying machine for active, worry-free fun flying. Some of the pilots in my flying club are just past the basic-trainer stage, and are now using flat-plate foamie airplanes like this Akro to get more air time without worrying about crashing a more expensive model. We also have club members who know how to fly pretty well. A few of them use these foamies to explore. Getting into wilder aerobatic maneuvers isn’t so scary when an $8 airframe is all you risk. Read the entire build article inside the Winter 2014 issue of Park Pilot.

All of the Akro’s foam parts are cut from 1/4-inch or 5mm sheet foam. Other materials are 1/32-inch plywood (fuselage doublers), 1/8-inch plywood (firewall and braces), 1/16-inch plywood (control horns), 1/4 x 1/2-inch basswood (wing spars and fuselage stiffener).

Any low-cost motor in the 100-150-watt power range is suitable for the Akro. The motor is screwed to the plywood firewall, and the ESC is held securely by Du-Bro Hook & Loop Material.

Use a 1500-2200mAh LiPo. Hold it tight with a strap made from Du-Bro Hook & Loop Material.

If the stress level of flying an RC airplane is in direct proportion to the cost of its airframe, you’re bound to enjoy a stress-free, relaxing day at the field when you build and fly Dick Sarpolus’ low-cost Akro.

Click here to download your free Akro Build It Plans.

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Comments

Robert Walbroehl (not verified)

RC plane article

Tue, 02/04/2014 - 19:46

Like the quick and inexpensive RC build. Thanks for the plans for the exact plane I have been wanting to put together.

Alan Russ (not verified)

full size plans

Fri, 02/07/2014 - 13:30

I need a tile print option for my printer. Is there a way to print the plans in tile format?

Alan Russ (not verified)

Tile format

Fri, 02/07/2014 - 13:32

Is there a way to print in tile format?

AMA Staff

tiled

Fri, 02/07/2014 - 18:03

Not yet. We first wanted to get the site launched to sync with the latest issue. Our next step is to go back and work on adding those enhanced features.

Keith Mc (not verified)

Tile Print

Wed, 02/19/2014 - 10:02

On a Mac you can either use Adobe Reader and select poster. Make sure Tile Scale it 100%. You can add Cut marks if you like and increase the overlap to help with alignment.
Another option is an App called SplitPrint which works great for tile printing, it also allows you to combine tiled pdf into a single plan. Great for creating an overview.

Allen Sharog (not verified)

Tile Print on PC

Sun, 03/23/2014 - 17:31

Works the same way as a MAC on a PC

Saul Acalinas (not verified)

Dick Sarpolus' Akro

Fri, 02/07/2014 - 18:07

Looks like an easy, cost effective build and I was just looking to buy a factory built plane like this. Thanks Dick and thanks Park Pilot.

Doug Wittenberg (not verified)

Tiled Plans

Mon, 02/10/2014 - 05:19

Good job on the plane but there is not enough information to build the plane without tiled plans.

AMA Staff

Winter 2014

Wed, 02/12/2014 - 08:24

Hi Doug, You can read the entire build article in the Winter 2014 issue of Park Pilot with many more photos and construction tips.

Joe Mariencheck (not verified)

Tile Printing

Tue, 02/11/2014 - 20:59

If you use Windows you should be able to tile print right from your own printer menu.. Save the plans then open in Adobe. Select print. In the menu select size = original, then select poster. You can select cut lines if you like. This will tile print from your regular printer.. Hope this helps..

AMA Staff

tiled printing

Wed, 02/12/2014 - 10:52

Thanks Joe for publishing the tip!

andrew pond (not verified)

brushless motor

Thu, 02/13/2014 - 15:36

what kind of brushless motor? it said 100 to 150 watt brushless. I look at tower hobbies not able to find the right one.

Ed (not verified)

tiled plans

Sat, 03/01/2014 - 00:00

Ref tiled plans. If you have adobe reader 10 on your computer, after selecting print you will get a box dealing with paper and page handling. Choose "poster" and adobe will tile it for you.
This feature is not available adobe 9 and earlier.

Alan Russ (not verified)

Akro

Sat, 03/01/2014 - 16:41

I scaled up the plans using a 4.5 multiplier and rounding to the nearest 1/8". I constructed to plane using white foam board from a local office supply. For power I used a 370 class motor ( Emax 2822/13 from Headsup Rc) and a 8 x4 GWS prop, 1300 50c lipo and 22 amp ESC. The flying weight is 23 oz. It flew with little trim, and performed like an intermediate sports plane. Fun to fly, and inexpensive to build. Build one and have fun.

Alan Russ (not verified)

acro templates

Sat, 03/01/2014 - 18:16

I have a basic set of templates. If you are interested contact me at [email protected]

Eric Hagen (not verified)

Motor used

Sun, 03/02/2014 - 23:13

I'm just getting started on my build but I ordered a motor I found on e-bay for under 12 bucks. It is listed as 150 watts in the specs.

Ray Cox (not verified)

interest grabber

Wed, 04/30/2014 - 21:57

I'm just coming back to R/C planes after being out of the hobby for over 20 years. I've always been resistive to the idea of electronic components "hanging out in the breeze", but this is something I will probably build in the near future, after I've knocked the rust off my skills with an electric powered SIG Kadet MK II that I plan to put in the air, weather permitting, within a week.

John (not verified)

Tiled plans

Thu, 05/15/2014 - 13:31

Thanks Ed for the info on how to get a print out for full size plans of this plane...The POSTER feature took 24 pages for the print out, now will have fun trying to put it all together....

Bill (not verified)

AKRO

Thu, 06/05/2014 - 19:03

A great park flyer and easy to build. For those who are interested in details, I wanted a smaller model than the original so I had the plans reduced to a size to fit the field I fly in. I also changed the basswood to balsa to keep things light. I took a copy of the plans that I printed on regular 8/11 computer paper to Staples and they scaled it to a 28" wingspan. I don't have rudder on this model. The specs are below. I love flying this model
Here are the specifications for my ACRO: I used 6mm (1/4") foam, Wingspan 28", Length 23.5". Motor Eflite 250, Prop EP 6" 6050, Eflite 10amp esc., Servos - Elev. Hitec 55, Ailerons -2 Hitec HS 35HD. (these are ultra small and fit into the wing), Battery - Thunderpower Prolite 730 V2 2cell. Weight - 6.4oz.

Shawn (not verified)

Versatile Design

Wed, 09/03/2014 - 16:51

Not only is this is a great little low budget R/C plane for learning and having fun with but it would also make a great foamy control line trainer for electric power or for 1/2A glow power if built from balsa and fuel proofed!

elgaeb (not verified)

foam

Thu, 01/28/2016 - 15:03

Where do you get the blue foam that you use? I can't find it anywhere.

David Ellis (not verified)

Foam source

Fri, 01/29/2021 - 23:16

You can find 1/4"X4ftX50 feet for less than$50. With that, you can build a LOT of RC planes.
Look/ask for 1/4 inch fanfold foam insulation. I have seen pink, blue, and yellow at various stores.....Home Depot, Lowes, Menards are local for me. Sometimes it will have a wavy surface. I pass on those.....

David Ellis (not verified)

Reinforcement materials

Fri, 01/29/2021 - 23:22

Instead of the expensive thin plywood, I use family size cereal boxes. (Cheerios) It is surprisingly strong, and with the savings, in $, I can make three planes for the price of one.
Of course, that does not include electronics, etc.....
Put it on with color side out for a prepainted body, or cardboard side out for your own painting....or not.