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Another Fliteskin ME 109 build thread

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Old 06-07-2015, 06:39 AM
  #651
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From your description it sounds like a stall-snap?
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Old 06-07-2015, 10:34 AM
  #652
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Wait a second, just noticed something you wrote.
You said the plane lifted off just fine and then rolled to the left or in other words the wrong way right? If the plane was airworthy then it will lift off just fine as expected. The unexpected roll comes from, possibly, reversed ailerons. Have you double checked the direction is correct?
Both times your take off was to the left but the turn is to the right and both times the plane has rolled left. Maybe Im wrong.
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Old 06-07-2015, 12:02 PM
  #653
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Erans,
We are all pretty upset about this, we know how much you worked hard on this project and it came out nicely done. There is a natural urge to figure out what happened and I know is easy to create explanations while we sit in front of the computer.
I hope at some point you figure out this thing.
Reg. your request, I have tis pic of the spinner, but I'm not sure what you really looking for. If you need I can take some more from an specific angle.

Best,



JoseG
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Old 06-07-2015, 04:57 PM
  #654
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w1n6urfa - Please have a look at post #600, page 24. There is a photo of the aeroplane while rolling on the first attempt. To me this do not look like a stall. The aeroplane was parallel to the ground as it was still running on the mains when it suddenly happened. Speed was very close to where I would expect it to rotate.
Chris Nicastro - The ailerons were checked by three people before both flights (including the Inspector), and were working to the correct deflection direction. At time of start of rotation left, I was not using the ailerons as I was still on the ground. I have applied ailerons once the rotation was taking place but could not bring the aeroplane out of the roll.
Jose - Trust me that I am intrigued as to the reason causing this. In my 28 years of flying RC I never saw an aeroplane doing this with no obvious reason.
As to the photo, I would like to see a photo similar to the one you have posted, but without the "dome" (prop and backplate only).
As a side note, I watched your Ta-152 video. Great looking aeroplane.

Regards,
Eran
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Old 06-07-2015, 07:40 PM
  #655
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In this photo (great shot btw!) the plane is airborne and it seems parallel to the ground but is parallel on the yaw axis, on the pitch axis is is climbing steeply!

Hard to tell without more pictures to see the sequence of events, I'd say its a combination of torque-induced left roll and stall-snap

I have maidened several 109's, prior to launching I attach a tail skid under the left wingtip as it is 99% certain it will hit the ground before I correct. Once airborne typically I will fly holding a lot of right aileron while a helper will trim that out - it might require the full extent of aileron trim!
But I'd rather abort the take off rather than force a rotation with elevator, that would be fatal

On the ESM 73" Emil (the worst behaving one!) instead of up elevator I use 10 degrees of flaps for the take-off. It is still hairy especially with any hint of cross-wind but milder than without any flaps

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Old 06-07-2015, 10:00 PM
  #656
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w1nd6urfa - Between the three of us watching both incidences, the torque roll was the most logical explanation. My ME-109 was powered by MVVS 40cc petrol engine with 20x8 prop, which, I believe, is much more powerful combination then O.S 160 with any prop you can bolt to it, which is powering (from memory) Jose's aeroplane.

The reason I am still not 100% with this explanation is that on both take off attempts, I was not anywhere near full power when the supposed "torque roll" happened.
As to the photo, please be reminded that this photo of the first incident was shot from quit a distance and an odd angle (I actually didn't knew it was taken until I got home and downloaded the photos from the camera. It was a friend of mine at the pit area who helped himself to my camera and took the one shot, which is this one). I am not convinced at all that stall snap had anything to do with it, but, everything is possible.
We can speculate until the cows come home as to the reason for both incidents, however, I do not think that we will ever get to a definite conclusion.
What is important is that I enjoyed the project. It was challenging, and thought me a lot, and, despite the final result, did not deter me from building more RC plans .

Cheers,
Eran
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Old 06-08-2015, 05:17 PM
  #657
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A picture is worth a thousand words....



Cheers,
Eran
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Old 06-08-2015, 05:37 PM
  #658
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Hey Eran,
Glad to see the sense of humor is not lost.
Cheers

Brian
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Old 06-08-2015, 06:08 PM
  #659
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Old 06-08-2015, 07:25 PM
  #660
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Ok, just checking.

in that particular photo what I notice most of all is the rudder, its neutral. If it was me that rudder would have been all the way right input trying to correct for the departure.
If your second incident was exactly the same, pretty close or so, to the first then Id say you need to be more aggressive on the rudder early on all the way until its fully flying.

Did you use flaps on take off?
Have you checked they are symmetrical?

I cant think of anything else to be honest. Lack of video and photos makes it hard to determine for me at least.

My first 109 did the same kind of thing as your describing. I had allowed it to roll out for what was to me a long distance, longer than Im used to for most warbirds. As soon as I pulled to take off it snapped over to the left also. This model type requires a gentle hand and shallow take off angle. It has to be going very fast before lifting off and it must be on the wing. Ive watched the full scale 109 at the Flying Heritage Collection in WA fly and they fly it very conservatively. Takes offs are low and long before gaining altitude.

Rebuilt it!! 3rd time is a charm, dont let it beat you!
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Old 06-08-2015, 08:56 PM
  #661
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This early video https://youtu.be/GDA-VYUdmDA shows the take off swing in my airplane, later after a few failed take off runs I started using grass only runways for take off and landing.



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Old 06-09-2015, 12:05 AM
  #662
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Chris Nicastro - Flaps were not used on take off, and yes, they were checked to be symmetrical.
On the first take-off run there was no swing, so no rudder was used to correct the heading up to the abrupt "lift off" which caught everybody by surprise. I am willing to bet any amount of money that there is no one in the world with reaction time fast enough to get the aeroplane out of the first "torque roll" (or whatever it was).
The second take-off attempt was very different, being done from the grass with the different geometry of the main undercarriage. I had to deploy the rudder almost from the get-go to maintain the heading. Again, even that we were ready for the possibility of "torque roll" due to past experiance, when it did happen, the speed of the roll left no chance for effective correction.

Jose - The swing you encounter at take-off looks nothing like my take-offs attempts. My take-off acceleration was more gradual, and the aeroplane was kept within heading in alignment of the runway all the way to the "torque roll" with no swing to the side. The "torque roll" took place further away down the runway then your lift off point (from what I can asses from the video), but I would say at what seems to be similar speed to your lift-off speed at that point (if not at faster ground speed then yours).

Cheers,
Eran
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Old 09-04-2015, 09:46 AM
  #663
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Hi Erans,

hope things are going well down under. I'm thinking about replacing my OS1.60 engine for the 30cc MVVS on my Yellow14.


I know you have experience with this engine, do you have any recommendations?

Regards,

Jose
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Old 09-04-2015, 04:10 PM
  #664
erans
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Hi Jose

The MVVS 30cc is an excellent powerful and reliable engine. If you remember, I bought mine for use in my own ME-109, but another aeroplane needed an engine and the 30cc gone, leaving me with the 40cc (which ended up being unsuitable...).
I have over 20 hours of operation on my MVVS 30cc, and never had a dead stick or an issue.
The only thing I don't like in the MVVS 30cc is the throttle arm geometry, but this is easy enough to resolve with a ball link.
I am also using Bisson muffler, replacing the huge MVVS muffler.

Cheers,
Eran
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Old 09-04-2015, 06:27 PM
  #665
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Thank you Eran, is the one with the side plug that I'm looking for.

http://www.mvvs.cz/mvvs_30SP_e.html

JG
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Old 09-04-2015, 10:47 PM
  #666
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This is the one I have.

Eran
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