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cmulder's

"Throttle and muffler contraption"



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Post  OVERLORD Sun Sep 08, 2013 11:15 am

That's what I am at the moment. Below the video of the Jr Satan's figure 9.



Sometimes, it just hit the ground after a few metres. Launching was already widely discussed  but maybe other irregularities can be seen.

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Post  roddie Sun Sep 08, 2013 12:27 pm

I've been watching the threads on this plane... You did a beautiful job building it.  Are your controls set to "absolute least sensitive" or vise/versa? Have you tried flying with less than a full tank? Do you have sufficient outboard wingtip weight? I know there were concerns about tank location and c.g. and the weight of the Enya.
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Post  bullit132 Sun Sep 08, 2013 12:32 pm

 that looks exactly like my flying style!! im an expert at crashing and i know there is nobody as good at as i am!!!!!!!!!!!! lol! Beer Cheers 
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Post  Cribbs74 Sun Sep 08, 2013 1:06 pm

As much as that looks like a tail heavy condition to me, I wonder if your just giving too much "up"

If at first you don't succeed.......
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Post  navion34 Sun Sep 08, 2013 1:40 pm

Maybe I'm totally stupid : is the elevator is in neutral position when your hand (and the handle) is at your neutral ?

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Post  JPvelo Sun Sep 08, 2013 1:43 pm

Double check that neutral at the handle is neutral at the elevator. Don't be afraid to launch with a little down elevator. The worst that can happen is it will hit the ground, which it is already doing. It may just be a case of learning this planes launching idiosyncrasies.

Jm
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Post  OVERLORD Sun Sep 08, 2013 2:34 pm

Thanks for your comments. I reduced the line distance already on the handle. I definitely have to check that neutral position in particular as I had the same problem with the Blue Pants.  
I glued a 15 gram weight onto the wingtip.

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The tank is shorter than the one on the drawing. I postioned it so that the centre line of both tanks were at the same distance from the LE. The filling tube is at 45mm from the LE, the actual CG is at 50mm from the LE. I can imagine when this tank is full of fuel, that the CG moves back.

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To move the CG forward, will it be enough to use f.i. a heavier prop or should I better add some proper weight?

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Post  roddie Sun Sep 08, 2013 8:10 pm

If I were you; I'd re-check your "neutral" (as suggested) and try to fly again; with the added wing-tip weight. If flight characteristics improve; you've eliminated one variable. Note: the plans "do" specify different tanks for different engines... "Flying-wings" are a different animal...  if you deviate even "slightly" from a proven set-up... you can expect "drastically" different results. I think you're dealing with a c.g. issue... The added wing-tip weight shouldn't hurt anything... and I wouldn't change the prop yet... Get it to "fly-out" a tank... without any extreme maneuvers... If it "feels good"... you can then; adjust your control "sensitivity" accordingly... and take it from there.
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Post  roddie Mon Sep 09, 2013 11:25 am

Hey Lieven, I just realized Embarassed that you had added the tip-weight while building. I wonder if it may need more?
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Post  OVERLORD Fri Sep 13, 2013 2:11 pm

Here's the repaired and modified JR Satan:

I made a new skid out of music wire. I added the muffler with the cut off stinger. The strap-on bracket needed reshaping due to the narrow space between the cylinder and the leading edge. A 8x4 prop was fixed. The CG is now approx 3/8" more forward. Hope this helps.

Lieven

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Post  roddie Fri Sep 13, 2013 2:18 pm

You do NICE work Lieven! Good luck!

Roger
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Post  Ken Cook Fri Sep 13, 2013 8:29 pm

Lieven, the Enya .19 is 2 1/4 oz's heavier than a Cox Medallion .15 and this is with no muffler. I've seen the cylinder snap right off more than once when used on combat wings when they strike the ground. The wire will not support the weight and the muffler will inevitably strike the ground and the Enya strap is tough stuff. I would seriously consider losing the muffler. You need horsepower and the muffler isn't going to allow the engine to make full power. Enya's really don't like being muffled when used in control line like I mentioned. Just something to consider. Ken
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Post  OVERLORD Fri Sep 27, 2013 1:39 pm

Thanks for your comments.

I've thought about what you wrote in your post, Ken. We discussed this muffler stuff before. I cut of the stinger as you said; the opening was a lot bigger than original. The wire skid would not resist a shock but it will at least kill it before it bends instead of breaking. So today I gave it another trie. I reduced the line distance on the handle. Adapting the launching technique as explained before, the plane climbed again, did a loop and hit the ground. The prop broke, so immediately, I fitted a new one.

I use a self manufactured biased hard point handle.

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In order to limit the up movement when launching, I attached my handle upside down to the wires forcing my wrist in an upward position. Amazingly, it worked. I got the plane flying. As it got up to speed, it was very fast and unstable. It was continuously flying like a roller coaster. I got very dizzy and wandered off my point. It wasn't fun at all. Until the plane hit a branch of a tree and went straight down. Once on the ground, I did one step and suffered the same fate.

Damages (to the plane):

A bent wire skid
The inboard leading edge broke together with some ribs
The 4 screws of the engine's nose piece came undone.
The muffler rattled loose.

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Post  navion34 Fri Sep 27, 2013 1:53 pm

Oh no...


I hope you will be able to rebuilt it...

If your plane is very too sensible try to move the gravity center forward.
Also you can try to fit a prop with less pitch....

Cheers,

Rémy
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Post  RknRusty Fri Sep 27, 2013 2:31 pm

navion34 wrote:....If your plane is very too sensible try to move the gravity center forward.
Also you can try to fit a prop with less pitch....

Cheers,

Rémy
I agree with Remy, it sounds tail heavy. Roller-coastering is an unmistakable symptom. I know it's frustrating, but if you get it balanced, you can control it. Maybe give it a lead necklace around the front of the crankcase or somewhere as far forward as you can get.
I bet it was an exciting flight to watch up until the tree jumped into the circle. I've had maiden flights that were like flying a wild pig too.

I like your saw handle grip, good idea.

Rusty

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Post  OVERLORD Fri Sep 27, 2013 3:17 pm

I thought by putting on the muffler and a heavier prop, that would move the CG enough forward, but apparently not. The muffler will stay off. I will try to correct the CG with lead. But first thing to do, start the rebuilt.

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Post  JPvelo Fri Sep 27, 2013 5:25 pm

Congratulations on a successful launch! Once it is rebuilt I would add nose weight. I would also mount the prop backwards to slow it down until you grow accustomed to the planes handling.


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Post  Ken Cook Fri Sep 27, 2013 5:31 pm

I have to ask how fast it was going. I've always made mention that until a wing gets up to speed it can be a wild ride. I find it almost impossible to believe that this plane is tail heavy especially using the muffler. If not up to the proper speed coupled with too fast controls will yield the same results as described. That handle to me is too much. I don't mean any disrespect here, just my observation. This plane only needs to be flown with a gentle rocking of finger tips. That handle must weigh a bit and a light weight handle is certainly helpful. The handle spacing in my opinion shouldn't have the lines exiting the handle more than 2" apart. I don't recall the bellcrank, but I do remember it being a Brodak nylon. The kit version recommends a 2" which is way too fast and thus requires a extremely tall control horn to tame it down correctly. Ken
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Post  Cribbs74 Fri Sep 27, 2013 6:54 pm

Welcome to the club!!!

I would listen to Ken's suggestions as he has helped me numerous times and has never been wrong.

I agree with the others as well as it does sound tail heavy. Very strange.


Apart from that I am wondering why the front half of the case came loose. Do you have a vibration issue?

Sorry about the crackup, but now that you have one under your belt it will fly better. They always do.

Ron
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Post  roddie Fri Sep 27, 2013 7:46 pm

Lieven, Sorry about the landing... but the first few seconds of flight must have been a real RUSH though... I'm guessing you made enough laps for the plane to get up to speed... The "porpoiseing" is a killer... and will make you dizzy real quick, because it's not "pilot-induced". The "gut" reaction is to stare at the plane, and try to correct a condition that your not prepared for... and worse; may not be correctable in the air. This causes spatial-disorientation (vertigo) and complicates the situation even further. (I'm sure you understand exactly why you fell down)

Yes... your flight would "ordinarily" indicate a classic tail-heavy condition... but I have to agree with Ken on the control sensitivity. I asked earlier in this thread if your controls were set at the absolute minimum. When you get her repaired, make SURE that they are... and again; it wouldn't hurt to run with minimum fuel for the first few flights... as "less an amount"; as your tank-configuration allows, and still be able to get a launch. A "richer" needle setting wouldn't hurt, until you get used to how it flies too.

I hope you get the plane back in the air soon... you did such an impeccably beautiful job building it. I'm sure you'll figure it all out... and the damage looks like it's minimal.

Roger
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Post  Ken Cook Fri Sep 27, 2013 8:53 pm

I'm curious as to the balance point as the plane sits now. I have many flights on mine. Mine is balancing 1 7/8" from the leading edge which is 1/8" in front of the leadout guide. Most older designs and a general rule of thumb is to balance at the first leadout guide. I know you extended the booms slightly upon my advice. I'm well aware of the weight differences of most engines and I suggested the lengthening accordingly. I just can't accept that the plane is tail heavy when without the muffler the engine is over 2 oz's heavier. But as a baseline, I provided my balance point and I think we all would like to know what is causing this problem. My son and I both were staring at your pictures with a drop jaw look. That was a terrific build and your quite a skilled builder. These things have happened to us and I know how gut wrenching it can be. Don't give up on this one. Ken
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Post  pkrankow Fri Sep 27, 2013 9:25 pm

I agree wings are "twitchy" at lower speed. I rather don't like them for this fact alone. They look super cool, and are easy builds, so I have and fly a couple (but not that big)
Phil
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Post  navion34 Sat Sep 28, 2013 9:50 am

Lieven,

My little experience with flying wings showed me that these airplanes are not fun when :
you are at low speed,
you are at high airspeed,
the center of gravity is too back...

When you are out the flight domain it's not fun... In the flight zone very funny, outer this domain, big stress....

Rémy
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Post  OVERLORD Sat Sep 28, 2013 1:37 pm

Hi Guys,

Concerning the CG. When I finished the plane, it was at 2" (50 mm) from the leading edge. After adding te muffler and the other prop, it moved roughly 3/8" forward. But my forward lead out guide is at 80mm from the leading edge. Not that I think this makes a difference but my Jr Satran is slightly bigger with a span of 750mm (about 29 1/2") instead of the 736mm (29") of the plan. The width is about 8 1/4" and not 8". When using the rule of 3, Ken's 1 7/8" corresponds with 49.2mm on my plane. So not far out. After the repair, I will check the CG again.

Concerning the line spacing on the handle. During the first test, the line spacing was 85mm which is 3 5/16". That was then reduced to 60mm (2 3/8").It ts difficult to estimate the neutral position of the elevator as there is no stab. Could it be that due to the construction, the elevator needs to be a bit down in order to fly straight?

Lieven
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Post  WingingIt74 Thu Oct 10, 2013 4:37 pm

I almost wonder if it isn't the handle giving you issues, being an angled saw handle. A natural wrist would be perpendicular to your forearm.... just thinking outside the box.  


What do I know... I don't fly CL lol!

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