Hanger 9 Sopwith Camel (Pig) Land-Dings

[Mark Powell 2]

Wingman,

Your comment on 'slow acceleration' is interesting. On fullsize I was taught to slam the throttle open. Then the torque is 'set', and rather than have to make adjustments for both varying torque and increasing rudder effectiveness you only have to do the rudder. and even that comes quickly up to it's 'final' setting due to the constant flow from the prop due to the sudden, and fixed, setting of the throttle.

Love the Camel. There is one in my LMS. The video makes be want to buy it.

[Alan Wood]

Every landing flip in the first video was caused by the lack of rudder use. It is just a characteristic of the Camel and other narrow track planes that once they are slightly sideways they tip onto the wing tip and once your there you are in trouble. As the Camel has a short moment and high CG it flips after that. Rudder is the most under used control in modelling and is one of the most powerful and benificial to use. I think about 90% of modellers think they use it but only use it a bit on taxi & take off and forget about it.

Practice will get you there. The last approach was great and a boot of rudder would have kept that straight and on track.

[Mark Powell 2]

Anyone interested in the Camel should read 'Winged Victory' by V M Yeates. First published in 1934 and many reprints. It is purportedly a novel but is really autobiographical. Very highly regarded by WW2 fighter pilots, who sought it out.

Might even give an understanding as to how your model behaves. After reading it, if I had a model like yours I would move the CG back a bit and live with the resultant characteristics. Camels were deliberately designed to behave like that. Otherwise you have got a Sopwith Pup!

Agree with Alan about rudder.

Edited By Mark Powell 2 on 28/08/2012 20:08:39

[Martin Harris - Moderator]

Posted by Mark Powell 2 on 28/08/2012 11:44:23:

Wingman,

Your comment on 'slow acceleration' is interesting. On fullsize I was taught to slam the throttle open. Then the torque is 'set', and rather than have to make adjustments for both varying torque and increasing rudder effectiveness you only have to do the rudder. and even that comes quickly up to it's 'final' setting due to the constant flow from the prop due to the sudden, and fixed, setting of the throttle.

I can't argue with your full size experience which I believe is fairly extensive - other than some limited motor glider training during my instructor course I always kept the engine at the far end of a piece of rope or wire cable! However, this slamming open of the throttle technique goes against everything I've read and thought I understood...

I can see the logic in the case of a very marginally powered aircraft with maybe a smalish prop to minimise torque, airflow and P-factor effects but every manual or guide to flying prop powered aircraft that I've ever seen advocates smooth and slow opening of the throttle - with high torque warbirds needing a staged opening, in many cases, to allow the airspeed to catch up with the torque applied in order to maintain sufficient rudder authority.

In the case of models, we're usually pretty overpowered in scale terms so my teaching technique (and normal flying practice) has always emphasised a gradual power application to avoid rapid departures from the straight and narrow with consequent overcontrolling.

[Mark Powell 2]

Martin,

I was taught by the RAF chief test pilot of the Empire Test Pilot School at Boscombe Down, who enjoyed light aircraft and taught us, in our typical low powered training aircraft at weekends because he enjoyed it.

Thus his techniques may well have been very different from the norm, but I knew nothing else and have done it that way ever since.

Models? I slam it open to get it away from the ground ASAP. On my grossly overpowered 72 inch Astro Hog, this usually happens long before I expect it to. But I am not a particularly good model pilot!

PS: What is the optimum climbing speed of this Aircraft? 70 knots, Bob. Why are you doing at 71 then, do it right and you have a greater margin or error, not that errors are allowed in my instruction.

Edited By Mark Powell 2 on 28/08/2012 21:27:01

Edited By Mark Powell 2 on 28/08/2012 21:35:59

[PETER BRUCE - Eastchurch Gap]

Hi again all.

After listening to a number of your views I felt the fixed U/C was the way to go however after looking at the existing U/C I felt it could be a problem which would destroy the existing U/C so I have ordered another so I can play with the idea before I try it out on my model...

In the meantime a few issues have come to me regarding the design of this model - which is why I was very specific in asking like model owners to reply. I have now dealt with the two points I felt will help me the most until the new U/C bits come in and I can tackle the fixed axle component which maybe the final part of the jigsaw to sort this landing problem out. Have a look at this little video I made showing the mods I have just done and let me know what you think - The proof is in the pudding of course and until I can fly it and land it I will not know - see the video and let me know if I'm in with a chance.

You will see by the size and position of the big weight box that it must be an issue as so much forward inertia must be contained in its weight....

Let me know - Thanks Peter

Edited By PETER BRUCE - Eastchurch Gap on 28/08/2012 21:52:55

[Martin Harris - Moderator]

Posted by Mark Powell 2 on 28/08/2012 21:26:16:

Models? I slam it open to get it away from the ground ASAP. On my grossly overpowered 72 inch Astro Hog, this usually happens long before I expect it to.

Seems to work for you, Mark. Perhaps the difference is that my preference is towards a scale take-off to which end, I very often take off and climb at half throttle or thereabouts (unless I'm flying a Limbo Dancer, Panic, Pitts etc.)

I must say that my pupils have seemed to have had fewer problems keeping their trainers pointing vaguely the same way as they started their take off runs when they've been briefed to open the throttle slowly but I have heard the bang it open technique being recommended for twitchy fun flys which can then be off the ground within a couple of wheel rotations!

Edited By Martin Harris on 28/08/2012 22:07:19

[Mark Powell 2]

Peter,

lowering the weight looks a very good idea. But I was surprised to see some of the weight it at the side., thus higher up than it need be. I would have added it to your lower piece.

I think the smaller wheels might make it worse. Do not do them at the beginning, as changing two things at once won't tell you which has worked, and unless you put the original wheels back you won't know.

Fixed axle. I would have just built a new one from wood/wire from my LMS rather than sending to the USA., to me it only looks a couple of hours work plus painting. And don't bother with the fairings until you know it makes a difference. But I do not know your circumstances. I note in your video that the existing UC seems bound, but not soldered, in some places. May not matter as I don't know if it wobbles and jams or not.

Note these are just 'thoughts', I am not telling you what you 'should' do.

[PETER BRUCE - Eastchurch Gap]

PLEASE SEE VIDEO JUST ABOVE LAST TWO POSTS FOR PROPOSED CURE FOR SOPWITH CAMEL LANDINGS - SEE IF YOU AGREE THAT THIS COULD HELP...

 

Regards Peter

Edited By PETER BRUCE - Eastchurch Gap on 28/08/2012 22:13:52

[Wingman]

Have a look at my photo album H9 Camel/Saito FG-14B - I have used the lead box for the electonic ignition unit and my ballast was specially cast in two ingots to fit on the firewall which, although it increases the ballast weight required, sits right over the axle line which reduces the leverage it can exert on the fuselage.

I have also fitted bracing wires across the undercarriage which completely stops the jelly-like wobble that is due to the o-ring suspension

[PETER BRUCE - Eastchurch Gap]

Hi Mark and also Wingman.

Mark - I would have liked to have got the weight all the way down but the limit was the room I have behind the dummy motor cowl together with safe fixing points - lumps of lead dropping out at our flying field could get me a letter from the club secretary. Regarding the wheels I can see where your coming from on this however I think the slightly smaller wheels could be a help - we will see.

Wingman - all your points noted but it does sound like your power unit is heavier than my 82 FS. I tried to get the weight as far forward as I could so I could reduce the lead - I have managed to reduce the lead because the weight is placed further forward and by being lower down it should reduce the angular leverage the inertia has over the U/C when landing.

I considered using the lower firewall section for the lead but the extra weight needed (moving the weight back towards the CofG) would greatly increase the wing loading which I did not want to do.

Keep em coming as this is good brain stimulating stuff - Peter

[PETER BRUCE - Eastchurch Gap]

Wingman - Looked at all your pictures and I am interested in you U/C wire rigging but you dont have an image showing the anchor points - any chance of a few images to resolve this as the flex is an issue.

Regards Peter

[Mark Powell 2]

Peter,

I'm going to get one of these, landing not included.. I use a concrete surface. May be better. Or not.

That, then build the old and huge Keil Kraft Falcon seen on another thread. A further thread has restarted my interest in EDFs. This site is costing me a fortune!

[Martin Harris - Moderator]

I'd thoroughly agree with Mark's comments on your proposed solutions. Building a test undercarriage without the whistles and bells would seem to be a practical solution to the (quite surmountable with a bit of thought and basic engineering) practicalities of adding the articulating winglet axle fairing.Once you've seen whether it makes a significant difference then you can impliment the scale solution.

Edited By Martin Harris on 28/08/2012 23:26:42

[Wingman]

Peter I've changed the bracing wire setup from what is shown in the photos - it now goes from the top of the inverted 'U' at the wheel to the opposite right angle bend where the front strut fits into the fuselage so there is cross bracing above the axle line - set up with a very mild tension with turnbuckles.

Mark - unfortunately Hangar9 no longer produce the Camel so no more spares are being produced so the only spares available are what retailers have left in stock - I broke a cabane strut and eventually found spares online from a model shop in Indiana which I'm currently awaiting delivery on - at twice the price they would have been from a UK supplier

[dorset flyer again]

Have to say that I agree with a few others on here, the landing speed is too fast.

As the tail is bought down it wants to fly again, hence a low stall and resultant nose over or cartwheel etc.

[Biggles' Elder Brother - Moderator]

I think that PeteB and John Dimond have this sorted on the first page.

As the model slows the dominant forces switch from being aerodynamic forces to being ground force transmitted through the wheels. The model will always swing at this point - and the very narrow track doesn't help.

It has to swing when you think about it becaise of all the directions it could go in - straight ahead is a minimally, infinitestimal, possibility. Once a swing starts - unless checked - it will always tighten and end in a ground loop. The reason is the model's a tail dragger - so the CoG is behind the main wheels. As it swings, centrifugal force acts at the CoG to push the tail outwards - that tightens the swing, so the centrifugal force increases more and then the swing tightens, and so it goes on until the model attempts to dissapear up its own backside!. Note that all the connected axles in the world wont stop this - though they will lessen the side thrust slightly.

The real solution? - be quicker and decisive on the rudder. The slightest hint of a swing - correct it. If it starts to swing the other way (which it probably will) reverse your correction. A lot of pliots sort of relax and stop positively controlling the model once the wheels contact the ground - you haven't finished flying this model until it actually stops rolling.

BEB

[Martin Harris - Moderator]

Isn't the reason for the connected axle simply to lessen the tendency for the swing to start?

I'd certainly agree with the diagnosis of the problem and the role of the rudder in correcting the situation but it's not been helped by the excessive landing speeds causing a semi-stalled bounce where the directional stability is marginal at best. There's no substitute for having the tail skid firmly planted on the ground while the model is travelling in the same direction as it touched down...it then stabilises the roll out by acting as a sort of land based sea anchor.

I believe the roughness of the ground has also contributed to initiating the swings.

Edited By Martin Harris on 29/08/2012 01:14:43

[bouncebounce crunch]

Posted by Martin Harris on 29/08/2012 01:11:52:

Isn't the reason for the connected axle simply to lessen the tendency for the swing to start?

I'd certainly agree with the diagnosis of the problem and the role of the rudder in correcting the situation but it's not been helped by the excessive landing speeds causing a semi-stalled bounce where the directional stability is marginal at best. There's no substitute for having the tail skid firmly planted on the ground while the model is travelling in the same direction as it touched down...it then stabilises the roll out by acting as a sort of land based sea anchor.

I believe the roughness of the ground has also contributed to initiating the swings.

I agree Martin, maybe the skid acts like the fin on a surfboard helping keep the tail from sliding when going down and across the face of a wave so keeping your direction? getting the skid to stay on the ground sounds about right to me, as any footage of the full size landing, the pilots do just that along with lots of wagging the rudder.

[Mark Powell 2]

Various.

Skid/surfboard/sea anchor - beginning to remind me of the old 'Pylonius' cartoons from many years ago. BUT - it has been said that a 'three pointer' means the angle of attack cannot change later so it can't bounce. Unable to regularly test that theory myself.

Bouncing - come on, could you lot do any better on THAT surface, fast or not? His friends have all tried it. Doubt everyone is in a 'bad pilots club' and I don't think I could do any better. It is pretty rough. Not sure about all these finer 'directional ' refinements on that surface. And the real one was a stupendous bouncer, so I read.  These 'full size' niceties are all very well., but on a model it happens too fast. And full size planes are much weaker, so you have to do it.

Although I was one of its advocates I am beginning to think that fixing the wheels together won't make a difference.. Send to USA? No - I could remove the present axle, make a 'fixed' one in less than an hour, particularly as the original, as far as I can see, is attached only by the 'O' rings.

There is one of these in my LMS at the moment, or at least there was a couple of days ago. If it is still there this morning I am having it, particularly as you say its no longer made. I don't really like ARTFs, and there are lots of plans or scale drawing for the Camel. It is just that I have found all WW1 biplanes to be much the same. Got a Flair SE5A and a Puppeteer, can't be bothered to build a Camel, this will do. Its nice 'sit' in the air, from the video, and the 'Winged Victory' book, have convinced me to spend more money. Again.

I will make the weight modification but no others. I will try to fly it skillfully (unlikely).

Edited By Mark Powell 2 on 29/08/2012 06:20:57

Edited By Mark Powell 2 on 29/08/2012 06:21:33

[Mark Powell 2]

Again, just a thought. If you use the correct size Flair wheels, they are REALLY heavy, compared to (say) the Williams. Might be able to remove a little of the noseweight. And they are right at the bottom....

[John Olsen 1]

I like the idea of moving the ballast down, I wonder if you can also get it further forward? The reason being that by doing so you would need less. So if you were able to get the lead right up against the front of the cowl you would be able to get the CoG in the right position with a lower overall mass for the whole aircraft. That may not necessarily help with the landing problem although it would reduce the stall speed.

I did this with my DVII, which probably needs it less...I looked at the provided weight box and thought "that is too high up and too far back". So I mounted the lead under the engine mount and as far forward as possible. There is a photo in my album although it does not show the lead very well, the slab is about two inches square by about half an inch thick, and brings the Cog to the most forward position suggested, which makes sense for me since I am very much a learner. Mine is mounted on extra long engine mounting bolts with an extra set of nuts. Good washers are also needed since vibration will help the nuts pull through the lead if they are not big enough

The thory behind this all is that the lead is providing a moment, eg a force times a distance. The distance in this case is the distance from the CoG (with the lead in place) to the centre of mass of the lead. So let's say for the sake of argument that with the lead in the original position its centre of mass was 3 inches from the CoG. We move the lead forward an inch, so now it is four inches from the CoG. We need the same moment to keep the CoG where it should be, so now we need 3/4 of the mass of lead. So if we had a pound before, we now only need 12 ounces, and the plane ends up four ounces lighter.

Even better savings can be made if the tail end can have the weight reduced, rather hard to do in this case without removing the covering.

A replacement undercarriage could be made with a tube to replace the existing axle, with a live axle inside it. With my lathe and milling machine I could knock one up in no time.....

John

[Mark Powell 2]

I tried casting a lead weight in the (alloy) spinner of my Topflite Spitfire, using the spinner as a mould. Then shook it out and glued it in with 24 hour Araldite. Needed.less than half the weight of it mounted above the engine. Worked fine, but I never 'liked' it.. The radio battery is above the engine too. No room underneath, the throttle servo is there.

Lathe? Milling machine. No. Just wire and a brass tube from your LMS. and a soldered on 'key' for the wheel. ten minutes in all.

Edited By Mark Powell 2 on 29/08/2012 07:44:26

[kiwi g]

Amazing how far off the problem a thread can get.. blip blip bllip. and i think the flyer in question has done a good job of landing the sopwith on that field considering the ground conditions..

I still say fly on the wings then the prop , Draggy old bipe with a nasty frontal moment , flying all the way to the ground doesnt work . . they like a little drag to slow the climb , as soon as the power is on it will lift again . lots of wing area there guys.

the split axle is interesting . so what is being said is this will stop the turning once landed..?? doubt it .Theres a better chance the sopwith will still hit one wheel first , most certainly on that field. it will still start and turn till the weight is off the wing.. its certainly a rudder issue ,

Its really a timing thing . blip blip blip . catch the camel on touch down and it will stop fast .Mine does.

[Mark Powell 2]

Not too far off, I think. Here's another one. Use a petrol engine, then you can 'blip' the throttle like the real one did!

The fixed axle is more useful on takeoff. Did wonders for a Flair Legionaire.

But - many modellers don't have a clue how to land properly. But I do NOT think that applies here.

Edited By Mark Powell 2 on 29/08/2012 07:53:49