rmh

you cant beat a tractor trimotor for being able to group the engines tightly. (Push me pull yous are worthless.)
they were the king of the early transport planes and pretty safe from one engine out problems (roll over and die.)
read your tables on how drag increases with increased size and go for it
I would bet -if you size the plane and net for two engines - the performance on three will be "just right". as for the 200 cc engines - forget the four cyl stuff

Antique

My Feedback: (4)

Props are available in any pitch you want, we have some 22x28 pitch Zingers and 22x27 carbon fiber race props...It just takes cubic money

rc bugman

My Feedback: (30)

All the research planes are put away for the winter and it is time to figure out how to sample a larger quantity of air for more bugs. Feel free to contribute.

In 2006, we successfully pulled 8 sq ft of net at 49 mph with a 3w-150 and at 56 mph with a 3w-200. The net mesh was the size of window screen. At 49 mph, the net sieved 1000 cubic meters (cubic yards) of air per min and 1150 cubic meters at 56 mph.

We need to increase our sampling volume by 50-100%. Target = 1500-2000 cubic meters per min. (Don't ask why, we are just nuts.)

The most efficient power/wt ratio for an engine is the 100cc size or the 150-157cc size. Engines larger than 150 cc gain wt faster than hp and props are not available in 10 pitches.

We are sticking with 3W engines because experience has shown that they hold up to our type of abuse.

We are seriously discussing using twin 150s (33 hp) or a Tri-motor using 3-150s (49 hp).

If we use our 200cc power plane as a guide then hp to net area = 2.5 hp/sq ft of net.

Therefore, 33 hp = 13 sq ft of net = 1600 cubic meters/min. and 49 hp = 19 sq ft of net = 2400 cubic meters of air per min. Of course, these are upper end values.

So, does anyone have any experience flying a tri-motor and anybody want to speculate the various single engine out effects on the plane?

Any comments are welcome even if you just want to state that we are daffy. Of course, this is university research.

Elson

dirtybird

My Feedback: (5)

Wouldn't you be better off with a small ultralight?

rc bugman

My Feedback: (30)

A small ultra lite is risking a human life.

We often fly in storm fronts during dusk.

We need to sample below 500 ft which is prohibited by FAA and risking a human life.

Elson

tkg

My Feedback: (1)

Can you make a parachute of the bug screan and pull it say 15 ft behind the airframe?

rc bugman

My Feedback: (30)

tkg

We have the mechanism all worked out. two nets of equal size attached to the top and bottom of the airplane as close to the cg as possible. One folds forward over the wing (top) and the bottom net folds back against the lower fuse. The "transmission" is attached to both nets and whether opening or closing, one net is helping the other since they are moving in opposite direction.

Towing a net is a bad idea. We gave up on it 10 years ago. Too much turbulence off the wing tips, net spins and cannot be opened or closed. Also takeoff and landing is a pain.

Elson

dirtybird

My Feedback: (5)

Keep the pilot on the ground. It should not be to hard to RC it

Crusty

Bugman?...do you have any good pics of what you have been using?...just interested in what your aircraft look like..are they own design birds?
I think the tri-motor idea is probably good reasoning

window screen mesh!!!!!!! blimey I cant imagine the drag...you must be working those 3ws Very hard..congrats on making that thing work

rc bugman

My Feedback: (30)

Crusty:

Here is an uploaded video showing a 3w-150 pulling 8 sq ft of net at 49 mph flying at 200 ft agl.

http://www.rcuvideos.com/view_video....f023bf5d0c018b

Elson

Crusty

thx for that...neat design on the net

zope_pope

While this is super interesting and very cool....

Why are you trying to sample bugs? For research, or for fun? Or tired of the mosquitos at the field?

rc bugman

My Feedback: (30)

zope pope,

This is actual university research studying insects of economic importance which use weather systems and thunder storms to migrate long distances. The insect I am currently working with overwinters in the southern US, migrates north each spring to the upper Midwest and Northeast and then migrates back in the fall to the southern states. The insect ins 1/16 of an inch long but travels the whole distance (one way).

Elson

zope_pope

Wow, that is really interesting! Incredible that the little guy can fly all that way!

Unfortunately I don't have any multi experience to help you out with though. I dont know why some are against the push me pull me design, because I have seen the design in use quite a bit. They are developing the Adam's Aircraft push me pull me corporate prop thingy (A-500 maybe?) out at the airport I fly full scale.

Its easy to fly even if an engine goes out, but I think cooling may be an issue on an aircooled design.

Birddog-RCU

My Feedback: (62)

Just spray the wings with 3M glue... no net needed but it will look a little creepy after a few million bugs.

NM2K

My Feedback: (14)

Why not cluster the engines similarly to a Boeing 727 utilizing unducted fans? This should minimize most assymetric influences an engine-out would produce. I would face the engines forward in tractor style. A canard might even be feasible in such a configuration. This configuration would allow a lot more aerodynamic breaking during landing, favoring short landing roll out, although towing such a large net might make it a moot point.

The tow cabling would be attached to the wingtips, as your previous tow craft probably were fitted.

Forget the unducted fans. At low speed the propellers would be more efficient and are probably already available commercially.

Tower is selling a seaplane which has the engine mounted to a nacelle that is integrated into the vertical fin, IIRC. An engine in each wing, close in to the fuselage would minimize assymetric exageration of thrust with an engine-out situation. It would also move the engines far enough apart that their propeller arcs would not intermesh at any point. The latter could cause prop failures, etc. I just realized that this configuration would require that two of the engines would have to run in the pusher mode. That might be a difficult prop to find. But, with a strong fixed gear and a long enough sub dorsal fin, the props would not have an opportunity to strike the Earth in all but the most severe crashes. Not likely to happen...

Don't mind me, I'm brainstorming. With the brain that I possess, things get out of hand quickly. Thanks for making me think of something other than my aches and pains. I hope you continue to post on this topic.


Ed Cregger

rc bugman

My Feedback: (30)

Ed,

This has been a challenging project. The plane in the video is our best one yet and it flies very well considering the drag. Adding 7 mph makes a lot of difference in flight characteristics. It was a bit of a challenge to design a mechnism to open and close the net, to develop the relationship between net area and required hp and to find the compromise CG between net closed and net open. Then, we fly during dusk and full darkness and the plane lighting was an interesting development. There is a major difference between the need lighting for that occasional after dark fun fly and flying when your eyes are tired for a continuous 1.5 hrs.

For the "new bug plane" we have the planes already build. Originally, they were suppose to be single engine but slowly fell out of the sky with a 3W-200 when the nets opened. We are now trying to retrofit with multi-engines to continue. The planes look similar to the one in the video but are larger.

If we use the tri-motor concept with a 200 on the nose and 150s on the wings, we could leave the wing engines idling for takeoff and takeoff with the single fuse engine. we could then bring the wing engines up to full power as the net opens for a smooth transition. Or, we could link all three engines and use full engine power at all times.

We hope to have the first plane ready for test flying in January and with snow cover, the test flight will be off skis made from youth snow boards (tried and trued method).

Elson

tkg

My Feedback: (1)

Cri-cri is the solution to making a twin out of a single. A little goggle with get you the info you need on Cri-Cri.

MinnFlyer

My Feedback: (4)

Hmmm, I wonder if that would work for Fish???

Antique

My Feedback: (4)

How about a REAL engine, a twin cylinder 280cc Herbrandson drone engine, or the Limbach 275 twin, same cylinders but a little lighter crank..The 280 was designed to fly a drone for 6 hours at 7000 rpm with good (for the size) fuel economy....26 hp stock on gasoline...Only drawback is the weight, about 14 1/2 lbs RTF with C&H syncro spark ignition....The Aquila drone it flew weighed about 400 lbs....
I could post the speed we get from the race version but sinergy gets upset

rc bugman

My Feedback: (30)

Ralph,

I thought about a real engine of large displacement but then the problem becomes props of the correct pitch. I know that custom props are available, but the money well has a shallow bottom and we frequent damage props when landing under less than ideal conditions (after dark, rough runways etc). When pulling draggy loads, you need the engine to be in "low gear" with a 10 pitch prop because there is so much prop slippage that the engines get real hot real quick with the higher pitch props. On the 200 powered plane pulling 8 sq ft of net, we lose 25 mph when the nets open.

I compare the task of pulling nets with driving from Phoenix to Flagstaff in a loaded air cooled VW. The VW will pull the hill to Sunset Point in 4th but you will cook the engine before you get there. Shift to third, keep the rpms up, keep the air moving across the cylinders and you will top out of that long steep climb with no problem.

When propping these engines, I have learned to prop to the higher end of the rpm range with a 10 pitch prop regardless of the engine/prop recommendations. For example, the smallest recommended prop for the 3W-200 is a 34 x 10 but that didn't work in the net pulling application. We use a 32 x 10 and turn close to 6000 rpms.

Keep the ideas coming.

Elson

Antique

My Feedback: (4)

The 280 has been run as high as 12,000 on the factory dyno, rpm is no problem....We run 9000 all the time....
FWIW, my little 2.0 4 cylinder turbo Daytona used to go up that hill at 80+ mph

Charlie P.

Only flying fish.

Seems that something like a Flying King with a collection net slightly below and behind each wing (so as not to interfere with the aerofoil) would be able to loft a sizeable amount of screen net. Perhaps attached to each wing tip and the fuselage behind the wing saddle. For take-off and landing you could spool them in with a sail-trim mechanism from a R/C sailboat. A purse seine attached to the rudder tips in the rear and hinged at the low inner and outside upper corners would flop open when tripped and then could be mechanically closed for landing. Top to bottom appears to work, but whenever I swipe at a bug they usually jink low. Do you trap more in the lower net or the upper one?

DKjens

My Feedback: (50)

When I had this 36x11 Tenessee Prop on my Herbrandson280, it would not fly very fast, but it would pull like crazy. Hovering the 55 lbs Yak was right above idle, and pull out was great. I think you could have Tenessee Props make you these props for about $100 a piece, and you could always kill the engine at the last moment when landing "in the dark."
As Ralph said, the Herbrandson is next to indistructable, but it may be hard to aquire as many of them as you need.
DKjens

rc bugman

My Feedback: (30)

DKjens and Ralph,

Lets look and analyze the possibility of a Herbrandson 280.

What rpms did a 36 x 11 turn on the ground WOT?

What is the approximate engine wt with mufflers ignition etc?

What is the HP rating?

What is the fuel consumption of gas/oil per min at WOT? A guess? I would guess 280 - 300 cc of fuel per min or 10 ozs per min.


Charlie P.

A flying king is too small of an airplane. The plane we have is a 12 ft wingspan with a 2 ft cord with lifting tail and our wing loading will be around 70 oz/sq ft fully fueled with 3 gallons of fuel.

Your net idea is too complex and all of those lines get tangled. Did you see the video clip? I think we have the mechanism worked out with the top net folding forward and the bottom net folding back. At 50 mph, the bugs can not avoid the net.

Where do you live in upstate NY?

Elson

ps Ralph, if your daytona could pull that hill at 80, it was not loaded heavy enough and it was liquid cooled which is more efficient.