FlyingTigersAA

Hello all,

I'm a Mechanical Engineering senior on a team competing in the SAE Aero West competition this April. We've built an aircraft (senior project) that has a gross total weight of about 35 lbs. We will be carrying a static payload (10 lbs.) and 4 dynamic payloads (2 lbs. ea. / 8 lbs. total). We were using a YS 45-fs engine, but unfortunately it is no longer working. We've been using a OS 55 for the time being, but it is out of our engine class.

Our pilot says the OS engines are the most reliable, so we've been looking into the OS 46 class. I was wondering if anyone has advice for which ones to use. Our goal is to fly over the target and drop our 4 dynamic payloads onto it from 100 feet in the air. The wind is usually around 10-15 mph at the competition site. Are there any OS engines that are reliable in higher winds that can pull a 35-lb aircraft? Any suggestions greatly appreciated.

MaxSouthoz

Hi FTAA

This sounds like a very interesting project. Are you going to post it anywhere?

I'm not experienced enough to give you any advice on OS engines, but I would like to follow your project.

Regards
Max

R8893

My Feedback: (20)

Several years ago I worked with a team from the Univ. of Cincinnati. There was a restriction on takeoff distance then, 200' I believe. I was their pilot and we flew with a gross weight of 33 or 34# and a .61 engine. Just barely made it up in the 200'. I felt that the limiting factor was the thrust (F=ma) to accelerate the mass to takeoff speed. I also felt that a significant improvement over what several teams achieved (about the same gross weight) would require developing a constant speed propellor. (! am a chemical engineer, so add the appropriate grains of salt!)

The current production OS 46 will be the most powerful you can get. I wish you the best of luck lifting your target weight.

Chuck

RCFlyerDan

My Feedback: (54)

A couple years ago, I worked with FIU seniors on this same project for an SAE/Lockheed competition. They had to design, build and fly a plane for the max payload off of a 200 foot runway for take off and land in 400 feet. At that time, everything was electric powered for that event. Everyone kept having issues with the speed control, a limiter that SAE/Lockheed provided, and the electrical pulses or something that I didn't understand. We, I was the pilot, were able to come into 3rd place even beating Georgia tech! They were just too happy about that result. They airplane that they designed was one of the more conventional planes with the weight going in the belly. It looked like a Sig Kadet with 2 vertical stabs. They weren't in the event to drop the payload(bombs), just flying. The plane carried 11 pounds of weight. There is also a lot of strategy to win. The plane maybe able to lift the payload, but it has to get out of ground affect. We had one flight that the plane lifted the weight, but didn't get out of the ground affect. The others two successful flights, I was never more then 50 feet in the air. It was the total of 3 or 4 flights. So, don't try to carry it all on the first flight and wreck the plane. There were a LOT of wrecks that day. So, hope your pilot is a model warbird pilot that is used to flying planes with a high wing loading. A 3D guy will have the most issues flying this type of plane if he has never flown one. Otherwise, you will do all of this work, only to have a pilot that messes it up for you. They also provide pilots at the event that volunteer from the local clubs. But, you are taking your chances. Have your pilot practice with an under powered plane. Or a plane that he currently has, but can only fly it at less then half throttle.
As far as the engine goes, as everyone has said, the OS .46 is the best engine out there for glow. Just make sure you have the right prop for the competition. It is a very flexible engine that can be used in racers using a 9x6, 10x10, for trainers 11x5, 11x6, 10x6, etc, You will want something with a flat pitch for the thrust. Hanger 9 used to use a 3 bladed prop on their trainers that had a lot of thrust, but not fast. The wind won't be the issue for the engine, but the high lift wing and depending on the fuse, will be a "box kite" and ground controllability will the issue.
If you don't know the main purpose for this event, it is all about head hunting for SAE and Lockheed. Yes, you are supposed to do this for your final paper for college, but that isn't the main purpose and why SAE/Lockheed sponsor the event. So, take your resume!! You will be the future bomb drop engineers.

I found their paper on the project:



Here is the 100% report, I am in the sandals in the Test flight:
http://mme.fiu.edu/wp-content/upload...5-1-Report.pdf

rgburrill

OS are indeed reliable engines but are also one of the biggest liars when it comes to power in their specs. That YS engine is probably the best one you could get.

Truckracer

My Feedback: (19)

That YS engine was an excellent engine in its day but that day was almost 30 years ago. Trying to get parts for it would probably be almost impossible today so I'd recommend a new engine. I agree with others, the OS 46 is a good way to go and will do well with a large diameter, low pitch prop your project will probably require. A 2 blade prop will be more efficient than a 3 blade especially in the diameter range that engine will be able to turn.

I 100% agree, find a pilot that understands flying a high wing loading, slow airframe. Your project is way out of the range of what a typical model would fly like. Good luck and please report back how things went.

pkoury

My Feedback: (7)

Take a look at: Dub Jett model aircraft engines and accessories

hsukaria

Or try NovaRossi engines, www.planethobby.com

Incidentally, you did not mention the required engine range per the competition rules. Does it also allow 4-stroke engines? If so, you might concider a 4-stroke engine for the higher torque output.

CK1

My Feedback: (60)

Is there a contest restriction against using a reduction drive with the engine ?
If there is a displacement restriction then bigger loads can be more easily moved with a reduction drive turning a higher pitched larger diameter prop .

RDJeff

My Feedback: (11)

You might also consider using a diesel engine, or a glow-diesel conversion. It would be lightweight, and torquey, turning a bigger prop a bit more slowly than the glow version, and using less fuel to do it, saving even more weight. Davis Diesel Development has what you need.

Truckracer

My Feedback: (19)

+1, a reduction drive could go a long ways to improving prop efficiency. When pulling a heavy load, there is just no substitute for larger prop disc area.

dhal22

Good stuff guys.

speedracerntrixie

My Feedback: (29)

Actually I would be willing to bet that if the YS .45 was sent into YS sales and service, Richard and company would be able to fix it as good as new. Not too long ago I sent them a DZ 140 that had a sheared crank pin. The DZ has been out of production for quite a while, he fixed it up and it has become one of my favorite glow engines.

Truckracer

My Feedback: (19)

Possible but the 46 2 stroke has been out of production a long time. Doesn’t cost anything to ask though.

MajorTomski

I second that statement. the pumped YS engine were much more powerful than their same displacement contemporaries, even the two strokes. You ARE using 20% nitro fuel or better on the YS aren't you? Most folks try to run 15% and the just don't run well

Good luck in the competition

http://www.ysengines.us/pages/repairs

RCFlyerDan

My Feedback: (54)

I think our OP College boy forgot this forum, since he hasn't been back for any comments since his original post. The engines for this event are very limited, since I have flown in it. It has to be even across the board for all competitors. That is why there was an electrical limiter given out the year I helped that limited the electric engines. I seem to remember that the other classes of competitors using glow were limited to props and fuel was even supplied by SAE/Lockheed. So, I doubt that 4 strokes, diesels, or pumped engines will be allowed. Not really any reason to talk about it anymore, if the OP doesn't come back to ask for questions or thanks for the advise given so far.

CK1

My Feedback: (60)

You know the college life ! , what happens today gets erased by tonight . Long hours of studying followed by long hours of drink... err... more studying and basketball games leaves no time for leisure .