Hello guyz!

I'm sure most of you have heard of flying lawn mowers and there is a website that sells a kit for a nitro powered one, but I could not find anywhere where an electric powered version exists, so I decided to try my hand at one.

Lawn mowers are the subject at nearly every meeting at one of the clubs I belong to, and last month a big to do was all about the need to repair or purchase new mowers, so I thought now would be a good time to inject a little fun into this otherwise serious topic that manages to overwhelm the discussions at said club.

The other club I belong to is an all Electric club and we fly from fields maintained by the county, so mowing has never been a concern... till now! Watch out for spinning blades in the air!

The project got started after flying the Sky Cutter on the ClearView RC Flight Simulator. I was really getting into flying this thing and decided to see if I could find a scratch build on RC Groups, but when I came up empty handed, the next best thing to do was design one for myself, which is what I have done.

The basic mower takes 4 sheets of FFF and the handle is 1 sheet of Ready Board which you can obtain at Dollar Tree stores. The wheels are made from 3/4" cooler foam (sheets you can purchase from Lowes or triple the cutouts in FFF and glue together.

I covered mine with 2" wide strips of color packing tape (from fast-pack.com) because it adds very little weight and gives a nice glossy finish. You could probably do the same with Ultra Coat or similar iron on covering.

The only wood in the project is a few pieces of scrap I had laying around to mount the Fults Gear nose gear which I had laying around from my old balsa plane days and a strip on which to mount the rear landing gear and some 1/8" lite ply for the firewall.

I have not flown this one yet, but the CG should probably be around 7" behind the leading edge I would guess. I wanted to show off the mower a bit before trying to actually fly it, just in case it turns out to be a 1 flight deal. I rigged a little sound box from scrap foam and spare receiver, 10g motor and ESC that raps a piece of velcro when the motor turns, making an engine sound. I bound the sound receiver to the same channel as the receiver in the lawn mower and tied it the the gear switch on the transmitter, set the throttle control on the lawn mowers receiver to just turn the prop and set the throttle cut switch (DX8) to use the gear switch.

At our electric clubs meeting (today), I did a demo where one member played like he was pulling the starter rope while I activated the gear switch out of sight of the crowd. The sound box came to life and sputtered as the prop turned over. We did this a few times and then pretended to set the choke and the final pull "started" the engine.

You can view a video I took of me operating the fake mower here http://youtu.be/qDmZeSIEC7M. Attached files FlyingLawnmower_V2.skp (17.1 MB)Â

 

Awesome Flash! I have the Flyingthingz Flying Mower with a 55ax nitro motor and the kids love this. I would love to build an electric version so I can fly by my house. Looks like we have a new project in the line up
Great Job
John

 

How much throw do you have in the ailerons? I read the manual at flyingthingz.com and they said they use a maximum of 1 1/2" of up and down. I am not sure if they mean a total of 1 1/2" in each direction or 1 1/2" total from end to end.

I will probably setup my dual rates for both, but I suspect this could be a bit hairy to fly if too much throw is allowed.

 

Hi Flash,
I run mine at 1.5" full up and full down, so about 45% each way. This was one of the most crucial parts of getting this bad boy a float Before building mine, I had at least two friends build one with no success of getting it off the ground. So I built mine with manufacturers specs and figured with the counter torque of the motor that using full deflection on take off would be essential! I think that my buds couldnt get it off the runway because while they were cautious of running high rates on maiden, there was not enough deflection in aileron to keep this flat plate aircraft from flipping over on itself. I am not sure that with electric motor if you have to worry about this but I would suggest running full (3D) Rates on take off but maybe add 60% expo just in case....
Also I find mine to fly much easier inverted but it still looks cool upright but kind of touchy LOL

Good luck on the maiden!

Cheers
John

 

I notice that even on the simulator, you have to get up a lot of speed and then full up elevator to get airborne, so I can set elevator controls to throw more than ailerons and dual rate it for once I get in air. I'm just concerned aileron throws need to be reduced to prevent being twitchy.

I noticed inverted flying on sim is easy. Good to know real one is same.

 

I would agree with that Flash, I think by running higher Expo numbers around 60% it should take out the over sensitive feel. I am running Reduced throw on my elevator to 50% of full deflection so this should help keep it stable. I think having the elevator throw lower is more crucial than the aileron. Also I would have the dual rates ready for a quick transition once you are up on the air just in case Cant wait to see yours flying and best of luck to you!

John

 

Always try to bring a little levity where I can. Life is too serious sometimes. We did this at the club meeting and it got a lot of laughs there too.

 

Did the maiden this morning. It flys! CG should be 8" from leading edge, but I could only get 9" with a 2200 3 cell pack in the nose so it was a bit tail heavy.

AUW was 40oz with the 2200 pack in place. I could have gotten the CG to 8" by putting in a 5000mah pack, but would have added so much more weight I decided against it.

If I make another one, I will add another inch or inch and a half to the fuse section so that I have more room to move the battery forward and that should redistribute the nose gear weight forward as well to give better CG adjustment range. I will also make sure my nose gear is lowered enough to give some wing incidence for takeoffs.

The first takeoff attempt was downhill and I don't have the nose gear raised far enough to get air under the wing sufficiently so I could not get airborne. Second attempt was to takeoff in the up slope direction and it lifted off with ease.

I compensated for the bad CG with elevator trim. It does take a full 1 1/2" throw (in both directions) to control it once it is flying. I was worried that would be too much throw, but it turned out that it was needed. I may make a high rate setting with still a bit more throw in it.

I would have had video, but my camera man set the focus up close and all of the video except for the up close shots came out blurry.

I stalled on landing, forgetting I need to keep speed up and not being able to get a good view of my glide slope, but did only minor damage. Next time I will know to keep the speed up.

Just have to glue one side of the fake motor back to the top of the wing and it should be ready for another day.

I am pleased with the overall performance. The maiden pointed out the things I need to adjust and it lived to fly again, so I am quite happy with the outcome. Attached files

 

Great Job Flash! Good to hear the results and look forward to your flight updates

John

 

2nd Maiden yesterday at Pear Park, which I really don't like to fly from, but was anxious to get some video.

This runway dips in the middle and that was actually helpful since it catapults the plane into the air as it rises out of the dip. Other than that, I hate everything about it. This is probably the only runway in which you takeoff and land from one end of the runway! The tree line behind us has two openings which sets up a vortex at the far end of the runway and we constantly have crashes when we enter this zone.

At the far end of the runway is a ball field. Basically, we are flying in a drainage ditch between two ball fields. The ball fields are posted that ball players should not be on the field during our posted flying times, but yesterday, the ball players showed up and insisted on being on the field while we fly. I sure would have liked to seen the look on their faces when I dropped the lawn mower over third base!

Yep, the vortex got me again! The motor and speed control I used, plus the fact that the center of gravity is 1" back from ideal, as I turned into the wind for my approach to land, the wind caught me and I did not have any reserve power left to counteract it.

Although the damage was limited to just one fake wheel being broken into 3 parts which were easily glued back together, I was disappointed that I still have not been able to have a successful landing.

After getting back home, I pulled the motor and speed control out and replaced it with a Turnigy G15, a 45A ESC, and a larger/stiffer 12x6 APC E series propeller.

The added weight of the G15 brings my CG back to 8" where I wanted it from the beginning.

I did manage to get some good video however, thanks to Roger Weir, one of our club members.

Friday will mark the 3rd attempt if weather holds. We will be flying from Hickory Point on Friday, which only has a dirt runway. It may present its own problems, but we'll see.

So anyway, here is the video from Wednesdays flight....

http://youtu.be/5iDAxNPe1YY

 

Yep, thats exactly how mine looks in the air You almost have to fly it with about a 15 degree angle for it to stabilize. You will enjoy it much better with the right CG a 1/2" will make or break this bird! Great Video and I always get a kick out of these strange flyers

 

I have to agree with the stall theory in this case. The vortex zone is just outside the fence right at the end of the runway. It's real. But I never made it that far. My guess is that there just was not enough power to counteract the stall since I was at full throttle already.

That has been remedied now that the motor has been swapped out. The Turnigy G15 and a 12x7APC E Series prop gave this baby a heeping helping of reserve power and put the CG right on the 8" mark.

CG is critical on this plane! 1" made a huge difference! I was way out of trim on takeoff this time. So much so I started shaking and I have not done that in years. I had to add 5 degrees up elevator to get back in control. But that is actually where they say it should be.

I think next time I will move the battery back to obtain 8 1/2" to see what that does. I got two flights in today with two good landings.

When it is trimmed out, it is really very easy to fly. I'm really not that great a pilot, but I do have a penchant for flying things that are out of the ordinary, like your surfboard for example. I think you would have a ball with the mower!

 

Depends on the motor you select. The Turnigy motor is heavy enough to balance with a 2200 3 cell. If you use anything smaller, I would extend the nose by an inch at least.

 

That would be interesting! Just keep in mind the drag induced by the handle components. You almost have to double the size motor that you would use for the same size/weight of a generic plane build.

1 mil depron would make great sheeting for the wing I would think, and keep the weight down.

I am not doing much indoor flying this year but I would love to see someone work up an indoor version.

Keep us posted if you decide to go for it. I think there would be a lot of interest in it.

 

I've had quite a few flights on the flying lawnmower now and have made a few improvements I thought I would share with you.

The foam wheels seem to be the biggest headache as they are so fragile they break way too easily.

I made a couple of new ones to replace the broken up wheels on the front (thats the ones that seem to always get damaged). This time I glued a FFF circle on the backside of each wheel to give it some needed reenforcement. Next I installed the wheels using Professional Strength Industrial Velcro.

The hope is that if they do break again, I will be able to simply pull them off and press on new ones. But better still, maybe they won't break apart so easily now that the FFF backing is in place.

Next on the agenda is the CG issue. I could use a bit more weight up front still, so I pulled my 30A ESC and replaced it with a 100A ESC which is a bit heavier. Because there was no room, I remodeled the hatch area and outboarded the ESC which gives better cooling as well.

The last area I addressed was the handle. Being made of Dollar Tree Ready Board was not the best choice. If the foam gets a few bends in it, which is too easy to do just taking it off and putting it on let alone bumping it, etc.

I decided to replace the handle with 2" wide 1/8" painted balsa. I designed a new mount which works exceedingly well and permits easy removal and installation of the handle. A removable handle is a must for transporting the mower.

This of course was a tad heavier than the Ready Board, so the CG moved a bit making it even more tail heavy, which was the one of the reasons for adding the 100A ESC, although it is nice not to have to worry about pulling too much current now. The Turnigy G15 requires a 45A ESC anyway, and my 30A ESC was too small to begin with, so this solved two problems.

The Flying Lawnmower continues to be a real attention getter at the flying fields. I was teased the other day as I was flying, about cutting the grass too high, and then taunted to fly it inverted. I immediately took up the challenge and went into a loop and remained inverted as I cut a swath of clear blue sky. I could hear "I was just kidding!" as the heckler could not believe I would actually do it. Attached files