RCM&E Dec 2018 - Ruckus Review Update

[Shaun Walsh]

https://www.aeromodellers.co.uk/forum/reviews-model-flying-shops-products-kits/33520-kit-review-max-thrust-ruckus-another-poly-project?start=15

 

[Learner]

8 minutes ago, Shaun Walsh said:

https://www.aeromodellers.co.uk/forum/reviews-model-flying-shops-products-kits/33520-kit-review-max-thrust-ruckus-another-poly-project?start=15

 

Shame he doesn't say how he fixed the issue! 

[Cuban8]

On 19/08/2024 at 18:23, Nigel Heather said:

Please don’t let my question cause people to fall out. 🙏

 

So where I am:

 

The first thing I did was to add some elevator - that reduced the effect and left it flying what I consider properly at low throttle.  I didn’t try adding lots of elevator to try and level out at throttle because the elevator is clearly deflected already so that didn’t seem the right answer - more like curing the symptom rather than the fault.

 

I then more than doubled the down thrust, it may have made a small amount of difference but not much.  Again adding more seems like curing the symptom.

 

Unfortunately, I don’t have access to an incidence meter - it would be great to see what it is but unfortunately I can’t.

 

So next flight I will loosen the wing and slip in some card near the leading edge, retighten and see what that does - I’ll let you know, won’t be until Wednesday at the earliest.

Re the incidence meter - although I've had a Robart instrument for many years, I made up a nice piece of kit from scrap ply and one of those digital spirit levels/inclinometers that you can get from the web for a few pounds. I needed to measure a much larger model than the Robart can handle. I always check the rigging angles of all my new models for peace of mind before a first flight, and it also saves a lot of guesswork should one wish to experiment or sort out a model with handling problems.

[Nigel Heather]

11 minutes ago, Cuban8 said:

Re the incidence meter - although I've had a Robart instrument for many years, I made up a nice piece of kit from scrap ply and one of those digital spirit levels/inclinometers that you can get from the web for a few pounds. I needed to measure a much larger model than the Robart can handle. I always check the rigging angles of all my new models for peace of mind before a first flight, and it also saves a lot of guesswork should one wish to experiment or sort out a model with handling problems.

I was thinking the same - I already have a digital pitch gauge for setting helicopter blades.

 

I imagined propping up the plane so that the tail is level, then attaching a homemade platform that attaches to the tips of the leading and trailing edge and then sitting the gauge on the platform.

 

But then shelved the idea as I thought that I've only got to be out by fractions of a millimetre with my construction and that would account to whole degrees.

 

Cheers,

 

Nigel 

[Nigel Heather]

So just to make absolutely sure that I am packing in the right place, the attached picture shows where I believe I am being asked to add packing.

 

Asking because it seems counter-intuitive to me, also because the plane is already scary to fly and I don't want to make it worse as I may struggle to keep it safe.

 

Apologies for the noddy diagram, art was never a strength, but hope it conveys the idea.

 

Cheers,

 

Nigel

[Peter Jenkins]

That is correct Nigel.

 

When you are in level flight at the same speed as before, the fuselage will be flying tail high the same amount you have increase the incidence.  The wing will then be at the same angle of attack generating the amount of lift needed to support the aircraft's weight.

 

Raising the tail, or lowering the nose amount to the same thing and the motor thrust line is lowered by the fuselage adopting a more nose down position.

[PatMc]

3 hours ago, Nigel Heather said:

 

I’m really struggling with this concept.  I’ve always been told that having a plane too nose heavy is better than having it too tail heavy.  That a nose heavy plane is more table and a tail heavy plane is more sensitive to the controls.

 

For example, often told that a plane advertised as with the COG forward makes a stable intermediate plane that is easy to fly but move the CoG back and it becomes aerobatic.

 

So if I have a plane that is balloon up and climbing fast as soon as I apply power why would moving the CoG backwards help that?  Why isn’t moving the CoG forward a more likely answer.  I’m not saying it is wrong, just that I don’t understand it because it is contrary to what I have been told 

The first sentence is true but limits the models speed range & might be fine for someone happy to fly it as a trainer or relaxing to fly very limited performance model.

The second sentence is also basically true. I think this is what you want, isn't it

The third will take some time consuming explaining with diagrams. I'll have a look at a couple of books I have & see if there's anything suitable I can crib & post but it's likely to be this evening or tomorrow. 

[Nigel Heather]

9 minutes ago, PatMc said:

The first sentence is true but limits the models speed range & might be fine for someone happy to fly it as a trainer or relaxing to fly very limited performance model.

The second sentence is also basically true. I think this is what you want, isn't it

The third will take some time consuming explaining with diagrams. I'll have a look at a couple of books I have & see if there's anything suitable I can crib & post but it's likely to be this evening or tomorrow. 

Bit I'm struggling with is suggestions that my plane is nose heavy and that I would associate that with stable, docile, flight possibly with a decent, not with bucking up and climbing fast.

[john stones 1 - Moderator]

A simple explanation could be, if it's nose heavy and trimmed to fly at a slowish speed, you would have up trim in the elevator, once you put more throttle in, the uptrim will cause model to climb, if there's a fair bit of uptrim, you'll get a pitching up effect.

[john stones 1 - Moderator]

Stab in the dark, is the wing secure, not moving in flight ?

 

[Nigel Heather]

32 minutes ago, john stones 1 - Moderator said:

A simple explanation could be, if it's nose heavy and trimmed to fly at a slowish speed, you would have up trim in the elevator, once you put more throttle in, the uptrim will cause model to climb, if there's a fair bit of uptrim, you'll get a pitching up effect.

 

28 minutes ago, john stones 1 - Moderator said:

Stab in the dark, is the wing secure, not moving in flight ?

 

 

 

On the maiden, checked the balance, that the controls were in the correct direction and the surfaces were all nicely neutral and aligned.

 

Take off tracked really straight and took off nicely. Absolutely no aileron or rudder trim needed but noticed the plane was climbing strongly.  Added a little 'up trim' (meaning that I pushed the trim button up to bring the nose down) but realised that it wasn't really helping so brought it down.

 

Tried the next day when there was no wind, same results, but that ruled out balloon because the the wind - though if I'd though about it I could have ruled that out because it was climbing regardless of direction of flight.

 

Then I more than doubled the amount of down-trust but this appeared to make no difference, or if it did it was very slight.

 

The wing is secure, not moving.

 

I was hoping to fly today, was going to try moving the CoG and packing under the leading edge - unfortunately pesky work have thrown in a late afternoon meeting so no chance to sneak of early to the flying field - so may have to wait until tomorrow.

Edited August 21 by Nigel Heather

[Nigel Heather]

2 hours ago, Learner said:

Shame he doesn't say how he fixed the issue! 

 

Yes a real shame, what he describes is exactly what is happening to me.

 

I'll also second the bloody awful undercarriage bolts - I fitted mine, and after fitting the receiver noticed something not quite right with the wheels and on closer inspection saw that the wheel bolts were really bent.  And what excessive force caused the bend - why, pushing down the receiver onto some double-sided sticky sponge to fix it in place - yep that's right, gently pushing down on the receiver was enough to bend the wheel axles - bloody Chinesium.

Edited August 21 by Nigel Heather

[john stones 1 - Moderator]

You added uptrim because it was climbing, by uptrim you meam you pushed the trim up ? giving down on the elevator ?

[Nigel Heather]

1 minute ago, john stones 1 - Moderator said:

You added uptrim because it was climbing, by uptrim you meam you pushed the trim up ? giving down on the elevator ?

 

Yep sorry, got that the wrong way round when typing, but definitely did it correctly in real life.

[john stones 1 - Moderator]

Not owned a Ruckus Nigel, but did test fly one for a clubmate, it was pretty straightforward and flew O.K, by no means flighty nor unpleasant, control was sedate ish. The lads saying the incidence is the cause sounds plausable to me, that would be down to design not a fault with yours, on 3 cell it's fine, given more grunt it don't like it and you'd need downtrim putting in elevator to compensate.

[Nigel Heather]

38 minutes ago, john stones 1 - Moderator said:

Not owned a Ruckus Nigel, but did test fly one for a clubmate, it was pretty straightforward and flew O.K, by no means flighty nor unpleasant, control was sedate ish. The lads saying the incidence is the cause sounds plausable to me, that would be down to design not a fault with yours, on 3 cell it's fine, given more grunt it don't like it and you'd need downtrim putting in elevator to compensate.

 

Maybe that is the issue - I'm powering using 4S, but I'm not letting Century/Max Thrust off the hook as they make a big thing of it being suitable for 3S and 4S in their advertising blurb.

 

I have more down thrust at the moment than I have ever put in the plane and it is not enough.  I echo the sentiment of the story by a guy with the same problem (linked above by @Shaun Walsh) when he says that it feels like it is going to need 90 degrees of down thrust.

 

Can't say that I am impressed with it.

[Shaun Walsh]

8 minutes ago, Nigel Heather said:

I have more down thrust at the moment than I have ever put in the plane and it is not enough.  I echo the sentiment of the story by a guy with the same problem (linked above by @Shaun Walsh) when he says that it feels like it is going to need 90 degrees of down thrust.

Wouldn't 90 degrees of downthrust make it a rotary mower?

[Nigel Heather]

41 minutes ago, Shaun Walsh said:

Wouldn't 90 degrees of downthrust make it a rotary mower?

 

Maybe I can get some use out of it 😀

 

But seriously, it's that feeling when I have more than doubled the down thrust, it already has more than I have every put in any plane and it isn't enough and people are saying to add more.

 

Just tried calling Century UK, I did send an email some days back but heard nothing back.  But I got through to someone in technical support who admitted he doesn't really know anything about plane, but he took my number and the has said he will get the guy who does to call me back.  Let's see if they do.

Edited August 21 by Nigel Heather

[Kim Taylor]

I honestly think that you need to scroll back to page 1 of this thread, where the o/p gives specific information on how he overcame similar issues with his Ruckus.

His findings back up my and others views that a more rearward c of g will improve or eradicate your problem. 

You may end up with the elevator at what looks like a funny angle, but as long as it flies right, who cares? You can't see it once it's in the air. 

Worth trying??

Kim 

[Nigel Heather]

1 hour ago, Kim Taylor said:

I honestly think that you need to scroll back to page 1 of this thread, where the o/p gives specific information on how he overcame similar issues with his Ruckus.

His findings back up my and others views that a more rearward c of g will improve or eradicate your problem. 

You may end up with the elevator at what looks like a funny angle, but as long as it flies right, who cares? You can't see it once it's in the air. 

Worth trying??

Kim 

Thanks, I hadn’t spotted that - I did read it a while ago but concentrated on the modifications for the battery fitting.

 

Note they recommend a CoG of 105mm which is 15mm back from what I have at the moment and 5mm back from the manufacturer’s stated maximum.

 

I’ll try moving my battery back - not sure I can achieve 105mm with some weight on the tail - have to see how it goes.

Edited August 21 by Nigel Heather

[Nigel Heather]

Hi sorry, to labour this, but the plane is already pretty nerve racking and I want to make sure that the changes I make are not in the wrong sense making the plane uncontrollable and likely to crash.

 

I've not been able to get to the field yet, I work full time and the weather hasn't been great so there has been no opportunity.  Hoping to get out over the bank holiday weekend but not a good start as I woke up to rain this morning.

 

So these are the options that I think are available to me

 

• CoG
• Down Thrust
• Wing Incidence (I can't change tail incidence because it is slotted in the fuselage)

I thought I had my own understanding of how aerodynamics works but would never claim to be an expert and I am doubting myself because I'm getting so much conflicting advice from forums and club members.

 

Down Thrust

Opinion is unanimous, add more down thrust is the answer.

 

My problem here is that I have tried it, I more than doubled the manufacturer's down thrust and it made little to no difference.  The plane had more down thrust than I have ever seen in a plane and adding more seems crazy.  As the guy who posted with similar experience to me jokingly put it, it feels like this plane needs 90 degrees of down thrust.

 

CoG

I've always thought:

 

Nose Heavy - stable but docile flight, heavy controls

Tail Heavy - unstable and sensitive, light controls

 

With my plane wanting to climb like an angel whether any power if applied, would naturally make me think that I should push the CoG forward, and that is what some of my club mates said when they witnessed the flight.

 

But equally, people on here are saying that I should move the CoG back, which is counter-intuitive to me, but I accept that the guy who started this thread concluded that the CoG was best at 105mm, mine is currently at 90mm.

 

Wing Incidence

 

I've heard

 

• "Look, I've been flying for over 50 years and I'm telling you, you need to pack under the trailing edge"
• "Look, I've been flying for over 50 years and I'm telling you, you need to pack under the leading edge"

 

Now bear me on this one, this is what I've been told in this thread - pack under the trailing edge - see diagram.

 

A club mate is adamant that I need to pack under the leading edge and seemed a little put out that I even questioned his experience and expertise.

 

So bear with me and explain where my understanding is wrong

 

• The issue is that my plane wants to climb like an angel under power
• The suggestion here is to pack under the trailing edge as per the diagram
• The tailplane works like a weather vane and wants to go through the air level and this sets the angle of the wing relative to the air flow
• Packing under the trailing edge will increase the angle of wing - raise the leading edge relative to the trailing edge
• This will increase the lift of the wing making plane climb more - which is the opposite of what is wanted
• If I wanted to reduce the lift then wouldn't I want to pack under the leading edge

Please help me understand where my thought process is wrong.

 

 

 

Anyway, when I get some decent weather, I'm off work next week so fingers crossed, I'm going to start with the CoG, because it is the easiest, because I have tried the thrust line without success and because changing the wing incidence feels like a fudge.

 

 

 

 

[Nigel Heather]

For anyone interested, I got to the bottom of the problem I was experiencing with my Ruckus - that it would climb strongly whenever throttle was applied.

 

I tried more than doubling the down thrust - this had minimal effect.

 

I tried moving the CoG - this had minimal effect.

 

Added loads of elevator trim - this got it flying okay, but not great, and there was a roll that I couldn’t quite get rid of as it varied depending on the attitude of the plane.

 

Then when replacing the clevises (I’d discovered that the supplied ones are very brittle) I noticed something odd with the elevator hinging.  The right hand elevator was fine, hinged on the centreline but the left hand elevator was not.  The outer and centre hinges were good but the inner hinge was set considerably below the centreline resulting in a bend in the left hand elevator.  I’d not noticed it before because I’d just be checking at the tips which were fine.

 

I contacted Century UK and they were excellent, quickly sending out a replacement tailplane.

 

Fitted that, removed all the elevator trim and it flys great now.

 

 

Edited September 20 by Nigel Heather

[Stuart Z]

Glad to hear you’ve got to the bottom of it. A very odd problem indeed. 

 

 Now enjoy !

[GrumpyGnome]

Glad you got to tge bottom of it. 

 

A lesson for all - check your models thoroughly for alignment, even if they're highly artf foamies....

[Peter Jenkins]

3 hours ago, GrumpyGnome said:

Glad you got to tge bottom of it. 

 

A lesson for all - check your models thoroughly for alignment, even if they're highly artf foamies....

Especially if ARTF foamies!