jessmeister76

Hi All

I am currently learnig to fly. I have a Boomerang 40 trainer with OS 46AX motor. Recently my plane when dead stick after a shorter than expected flight which lasted around 9 mins, before that I was getting aroun d 12 mins per flight. The plane crashed into a tree and got stuck (it was obstructing its path back to the field). Fortunately I managed to rescue it, although I did end up punching holes in the wings and vertical stabliser when trying to fish it out of the tree. The plane was patched up and has returned to service. No damage was inflicted to the motor or electronic h/w.

After the tree episode my instructor made a comment that my plane actually felt easier to fly, although I haven't noticed the improvement myself - this is a qualitative observation. However, it appears the fuel efficiency has significantly improved and the flight time has extended. I can get more than 12 mins with fuel to spare. In fact, my last flight I got 14 mins and there was fuel to spare. It is important to mention that the prop was replaced around the same time, but can't really say if this would explain the improvement in performance of the plane itself. I have been using the same type of propeller at all times, 11 x 6 although I changed brands from APC to screw master. (With the last flight I actually had to replace the prop again due to another mystery I will explain). Also after the tree crash I did have to re-adjust the positioning of the aerolons by loosening the screw thing on the servo and adjusting the pushrods, as the aerlon neutral position was thrown out of whack (ie with one aerlon was in neutral position, the other one wasn't). It is possible the wing shape or structure may have subtley been changed as it did take the brunt of the impact with the tree, but if the wing shape has been distored it isn't obvious to the eye at all.

1) So here lies my first question - can anyone explain what could possibly cause such an improvement in the performance of the plane, particularly fuel economy? Up until the crash I was dissapointed with the flight time as someone else with a boomerang 40 was able to get 20 mins out of the plane and he had an engine which was either the same size or bigger (not totally sure if it was also an OS 46 or OS 55 size). It isn't critical, but it is good to understand it if possible in case a similar issue arises again in the future and I need to troubleshoot it. My instructor hasn't come up with any explaination other than sometimes a good knock sometimes helps the plane.

2) My last flight, the plane went dead stick. Upon landing it was apparent the propeller was missing and actually unscrewed off. It would appear it actually came off in mid flight! I replaced the propeller and went to go for another flight and also found the glow plug had gone as well. Also coincidently the rubber band that tensions the aerial to the vertical stabiliser had snapped as well but don't think this is related unless the prop flying off happened to some how hit the aerial aerial and snap the band. The nut that holds the prop in place was also missing suggesting it unscrewed somehow. Note that I don't use a nose cone on my plane. One final note is the instructor did notice when replacing the glow plug it did seem a little loose.

Two instructors commented they had never seen a prop come off in mid flight. I am certain I tightened the thing pretty hard when I put it on. So any ideas what would cause the prop to come off in mid flight?

I just querying these issues as I am hoping to improve my knowledge to improve the reliability of my plane. It would appear the most common mechanical incident is the loss of thrust - haven't heard of anyone yet crashing due to loss of the control surfaces, although I am sure it does happen from time time to time.

w8ye

My Feedback: (16)

the engine backfired and kicked the propeller off.

You need to readjust your mixture controls

JohnBuckner

My Feedback: (1)

A loss of prop nut, propellor and even the thrustwasher in flight certainly can happen and I have seen it. In almost every case its caused by running excessively lean 'Or' excessively rich and will occur during throttle changes. A increase in duration is probably cause by the fact you may have been running excessively rich before.

Ailerons ajustment can change particularly after a crash, wings can be warped and any manner of changes. Check for wing warps (twisting) this will change aileron adjustment and on trainers its easy to twist the wing back into shape with a heat iron on the film covering.

bkdavy

My Feedback: (1)

Perhaps as you gain experience you are learning how to use the left stick (throttle management). Many beginners want to fly around at full throttle the whole flight, which just wastes fuel. As you gain experience, you learn to slow it down, reduce throttle on down legs, etc. The result is longer flights, better fuel economy. Also, as the engine breaks in and you improve the tuning, throttle response becomes quicker, which may contribute to the perception that the plane is easier to fly. Temperature changes affect the way the plane flys as well. Although harder on the pilot, cold air is denser, giving better lift, better engine performance.

Brad

Gray Beard

My Feedback: (-1)

A couple of weeks ago I lost my first prop from a plane. I teach my students to never just leave the ground and pull up at a steep angle just in case of a dead stick or some other problem. Good thing I was doing as I teach. Right after leaving the ground parts started falling off the front of my plane and I lost power. First thing was the spinner so I cut my throttle right away. Then the spinner nut then the prop nut and washer then the prop and spinner back plate. All this in just a few seconds!! The problem was or may have been the loose nut that was holding the wrench when I was putting on the new prop?? Props are to be tightened down very tight. I just can't remember putting on a new prop? I had been flying this plane for weeks and not doing any work to it. Maybe I had a back fire when starting it?? I can't remember one but it's the time of year when the weather is changing and I have to start leaning out my engines for the summer. What ever caused my prop to come loose is just one of those things I file under the Stuff Happens section of my brain and watch what I'm doing a bit closer!! Wood props tend to compress and need to be tightened up a little or checked often!! Just food for thought.

Robotech

My Feedback: (9)

Adding a second nut as a locknut will certainly lessen the chances of throwing a prop. Especially on a four stroke.

The prop change could have had something to do with the performance change. An 11X6 APC is a fairly heavy prop. I've had much better performance with a Master Airscrew 11X6 on the OS 46. Even better (speedwise) the 10X7.