kerpinis

Dear all, i ve been an RC flyer for the past 20+ years and today i came across a very hard question.
I work at a company tha manufactures Target Unmanned Vehicles and they currently use 3W-240 B2 on one of their planes.

QUESTION is:

What is the MAX working altitude of this engine?In other words what is the ceiling of this model engine, and in order to be more specific, would it work at around 10.000 ft?

Thanks in advance

Manos

DadsToysBG

My Feedback: (35)

I use nothing but 3-w but i've never tried going to 10,000 ft. I know a Piper Arrow will max out a 9500 ft. All you can do is try. The guys in Denver use the 240 all the time and they are 1 mile high. Dennis

kerpinis

I know...try and see is the best solution..Problem being that the cost of the Drone is i excess of 200.000 Euros so..risking the whole plane is not an option...
I have already contacted 3W and the reply was " These are model engines and they have never been used or required to be used at that altitude".
So i will wait to see if anybody flies at a very high elevation Field (8000 ft +) with this engine..

Thanx though!


p.s: I almost have my H9 Ultimate ready, except engine, batteries and powerBox....Is that 240 too big to use???

Tall Paul

I have a report from NASA, dated 1978, where they flew their Mini-Sniffer drone to 20,000 feet, and noted no engine problems to that altitude.

smokingcrater

a 4 stroke is going to be better at altitude then a 2, but with that said, at 10k it is going to run, if it can fly your plane is another matter. it will have lost alot of the power by that point.

kerpinis

Thanx for the feedback guys. Hey Tall Payl, about the "Mini-Sniffer drone" what engine did they use?? I will check online anyway...

Thanx once again...All feedback is still welcome..There has to be someone who loves Giant RC and lives high enough!


Manos

kerpinis

Got it!

"....The Mini-Sniffer I was then modified into the "Mini-Sniffer II" by removing the canards and the wingtip tailplanes, then adding tail booms and extending the wings, giving it a wingspan of 6.7 meters (22 feet). It was still powered by a gasoline engine, and made 21 flights to a maximum altitude of 6,100 meters (20,000 feet)...."

Tall Paul

One of the guys I fly with worked with Reed on those things..
They used a McCullough Go-cart motor ISTR.
The thing is written up in a AIAA Journal in 1978.
Sadly they don't have any copy available.
I have a xerox here under a pile of crap.. looking for it as we speak.
What they found was the pumper carb worked with the sea-level settings to 20,000.
when they wanted to go higher they invented a hydrazine motor something like a CO2 motor, and got to 55,000 feet!
.
Found the copy....
Aeronautics & Astronautics June 1978

."We made no attempts to optiimize the $180 out-of-the-box engine, or the tiny 22x13 wooden propellor for cruise or climb. At 5500 rpm and 52 mph cruise, the propellor operated at an estimated 55% efficiency. The standard two-stack pumper carburetor on the motor happily maintained the proper mixture ratio from ground to 20,000 feet. A typical climb started at 570 fpm and slowed to 170 fpm at 20,000 feet, with a constant full throttle and 8700 rpm.
"The engine proved amazingly reliable in freezing weather or hot summers when directions on the box were followed to make the initial carburetor adjustments.... After we shifted from automotive to aviation gasoling, the engine ran perfectly to 20,000 ft many times."
"These highly reliable, simple gasoline engines would suit several potential missions. For instance, the 35-lb Kevlar™-nomex™ structure mated with a 17-lb. go-kart engine, 25-lb payload, 15-lb control system and 135-lb of fuel could be launched from a truck catapault, fly 2900 mi. and stay aloft 53 hr.
A more optimum engine-propellor combination- perhaps a four-stroke engine with a large geared propellor- might extend the range to 6000 mi or more."

kerpinis

Thank you for your prompt response Tall Paul, i have tried to get as much info as i could and still awaiting to see any more feedback in relation to the specific Engine, and/or the Walbro pumped carb.
As a matter of fact i read the above statement that "... was the pumper carb worked with the sea-level settings to 20,000 ....",
and it sounds overwhelming....

It is good though to mention that Rkramer said "...at 10k it is going to run, if it can fly your plane is another matter. it will have lost alot of the power by that point. .." and this is another important issue to check as i cannot think of a way to simulate at 10000 ft engine performance vs performance at sealevel

Thanx

Manos

Tall Paul

Manos, as NASA reported no problems other than a vapor lock on their first to 20,000 ft at 17,000 ft, the reason they changed to avgas, and with the experiences of the FAI r/c altitude record fliers getting well past 10,000 feet, your plane should be able to perform at 10,000 ft.