[Gyro in a twin?]

It's also good practice to avoid turning into a dead engine.  Although modern full size practice doesn't seem to give much account to this due to better rudder authority and airframe design, if you're flying near the stall (climbing to get some altitude for a circuit, for example) turning into the dead engine can result in a tip stall.

 

I remember watching a large WW2 model twin climbing out under good control at a show but it rolled over and spun in after attempting a climbing turn to fly a circuit into the dead engine.

 

Normal practice in full size also includes, typically, a 5 degree bank towards the live engine which gives an appreciable decrease in the minimum control airspeed - but I doubt that many of us would be able to maintain a small bank angle like that from the ground.

 

The track record of IC model Mosquitoes isn't too good so why not give yourself a little help with a gyro on rudder.  It may also help to add a little left thrust on the left engine to reduce asymmetry in the event of a starboard engine failure.  The Mossie doesn't have its fin in the direct propwash so needs all the help it can get on one engine with its highly tapered wings.

 

If you've any doubt it's probably best to cut the throttle and treat it as a complete deadstick - there's an old saying that the purpose of the remaining engine is to fly the aircraft to the site of the crash!

 

 

[David? Any chance of some forum stats?]

Due to some noise problems in years gone by, we're mainly a Saturday club (although we can fly 7 days a week)  and Sundays are nearly always the better day where we are!

 

...except this year which has had some pretty good Saturdays so far...long may it last.

[why does it dive alarmingly ??]

Paul,

 

Glad to bring a smile to your face.  To be honest, I've no time for the "nasty oily" brigade or the "electric toys" attitude - as far as I'm concerned, if it flies it's OK with me - but  I'm quite happy to poke a bit of fun in either direction!

 

The behaviour you're describing might be a rearward C of G - as you said, the dive test indicates C of G - a rearward C of G tucks under - there is negative stability and a forward C of G gives excessive stability, hence it would attempt to recover towards level flight rather rapidly.  This is counter intuitive to a lot of people.

 

Brian's suggestion to check incidence is also very valid.  However, the Puppeteer should build correctly as I believe the cabanes are pre bent and the mountings are preset.

 

The handling will feel a little different to the average sports model - mine wanders in yaw when flying reasonably slowly (it had a very tired OS 40FS until recently) and you have to work a little harder to make co-ordinated turns but take offs and landings are a delight as long as you don't rush them.  Great fun and so relaxing on a summer's evening...

[Filler]

Blue foam is used extensively for 1/12 scale combat models.  It's usually covered with ordinary brown paper soaked in thinned PVA and the result is an incredibly strong (and easily repairable) lightweight structure.  A single layer of brown paper is used but overlapped at the wing join for a few inches.

 

I've experimented with lightweight glass cloth/water based varnish but have returned to the traditional method.

 

The models pull some incredible G loads with barely noticeable (if any) wing flexing and mine are set up to turn from maximum speed with full elevator set to just below where they will flick out.  Directional change is instantaneous!

 

There are plenty of pictures, building & construction techniques on 1/12 scale combat models at http://www.geocities.com/CapeCanaveral/Runway/9790/ if anyone is interested - and new enthusiasts are always welcomed!  You wouldn't believe how much fun it is.

 

 

P.S. There's even a little something for Barry Weatherall at the bottom of http://www.geocities.com/dave_acesuk/aircraft2/airctype.htm

[E-flite Sea Fury]

Gemma wrote "It doesn't really show up so well in the photos but the shiny smooth surface of the epoxy really catches the light well and as it is transluscent it gives a good impression of a lens with depth.

 

I got the tip from here:

 

superpilotpainterperson "

 

A tip I recall from modelling headlights on a 1/43 scale D type Jaguar car many years ago was to leave the epoxy resin and hardener to flow together in a warm place (I'd think 20 minute epoxy or slower) for a few minutes and then apply it - this stops the formation of little bubbles that occurs during mixing.

[Tomorrow doesn't look too bad eh?]

Update to David's question:

 

 I tried them yesterday and they worked surprisingly well on what I would call "sticky" grass.  There was certainly a noticeable retardation when doing slide and goes but it taxied and manouevred OK and I could still do the long high(ish) speed slides - but without the marvellous scrunchy slithering snow sound.

 

I suspect flying from properly wet grass would work rather well.

 

Of course, having a comfortably better than 1:1 thrust to weight ratio didn't hurt!

[How windy is too windy?]

...and what sort of turbulence is kicked off from ground obstructions.  The same wind strength can give very different conditions at our site depending on it's direction.

[Are You Qualified]

..and how good is the Bootlace!

[Rx battery Placement]

Glad to have been of some help.  Hopefully yours will fly a well as mine - I've flown a  variety of Extras and without exception, they have all flown extremely well. There is something fundamentally right with the design that seems to translate to models of all sizes.

[Rx battery Placement]

Mine is the 5500198 SEAGULL EXTRA 300S (61-75 SIZE) (SEA-70B)
Wingspan - 63ins (160cm)

I can't see another 300S on Perkins' site but perhaps yours is an older (or newer) version not stocked by them?

 

Anyway, feel free to ignore all I've said so far!!!

[Rx battery Placement]

Bruce,

 

I have gone slightly over the top with a Super Tigre 90 (but it shouldn't be appreciably heavier than your 75, I'd have thought) as it was the only suitable engine I had when (thanks David and Co.) I rather unexpectedly won the model on an email comp on this site.

 

I marked the  C of G using a string stretched between the specified wingtip positions onto the fuselage (marked with black spots in the photo below) for easier balancing.  You can see my battery at the rear of the hatch opening.

 

 One thing I did notice when checking it is that fitting the wings made at least an inch rearward difference to the C of G position, which surprised me as I often assume the wings won't affect the C of G on models very much! Once the wings were on it did balance on the markings.

 

The main departures I made from standard were to substitute a SLEC tank as I was concerned about the original's capacity and eventually added canopy catches as the bolts were a pain in the wotsit!

 

By the way, did your tank fit in OK?  My original one wouldn't fit past a step in the front former so I needed to get the Dremel and files out anyway which simplified the decision to fit the larger tank.

 

 

 

[Rx battery Placement]

I did once make up a foam lined ply box to fit a battery alongside the engine on a particularly tail heavy Airsail Tomahawk that I was given by the builder who'd given up on getting it airborne.

[Rx battery Placement]

That's odd - on mine, the battery is cable tied behind the former at the trailing edge of the wings!  What engine have you got - a Cox .049???

 

 

[Lumpers]

They were right about it's toughness - I had to roll my car and squash it with the contents (or was it me?) to damage it beyond repair - normal crashing would hardly scratch it!

 

[aileron servo direction]

This isn't usually a problem as the servo positions/arms usually mirror each other, giving opposite movement. 

 

If you're using a Y lead and have a radio that can mix 2 channels, why not use separate channels for each aileron - then you can reverse them, if necessary, on all but the oldest radios.

 

Also, you'd get the benefit of being able to fine tune the roll axiality (if there's such a word!) using differential.

 

Last resort would be to buy an add-on servo reverser.

 

[Lumpers]

Just came across this old thread.

 

This has brought back memories as it's the model I learnt on.  Knowing better than anyone else, I constructed a wonderful scale single channel Cessna 180 and lobbed it into the wild blue yonder at Nomansland near St. Albans, back in '74ish.  This pitched up, stalled and demolished everything from the windscreen forward. Luckily this meant I didn't get the chance to hurt anyone by getting the rudder reversed once it was coming towards me...

 

Anyway, to cut the story short, after a few attempts with a (very) bodged repair, the wise old sages at the Watford Wayfarers advised me to go away and build a Lumpers, so I sent for the plan and built one, covered with the recommended nylon and dope. 

 

Over the next few months, I proceeded to throw the Lumpers into the ground in any attitude from vaguely horizontal to fully vertical (2 channel so it would often be at full throttle on the Enya .09) and apart from all the bits rattling around in the nylon "bag" it survived with minor repairs between each session.  I'm sure that Brian Cooper will remember the attempts to prise the transmitter from my hands - no buddy boxes in those days - or having the best part of half a second to try to save it when I'd realised the situation was hopeless and thrust the box into his hands.

 

Happy days!

 

Anyway, if you ever got any decent pictures of a Lumpers I'd love to see them - and perhaps you'd like to divulge why you were asking?  I'm sure I saw the plan listed somewhere - perhaps even close to home as I believe it was an RCM&E plan from 1968.

[Graupner G Sonic Propellor]

A piece of 0.5mm shim fractionally shorter than the circumference of the hole would do it.

[why does it dive alarmingly ??]

IF IT'S TWITCHY NOW WHATEVER YOU DO DON'T TAKE ANY OF THE LEAD OUT!

 

A forward C of G gives sluggish handling in pitch which is the opposite of your problem.  Most Puppeteer owners have needed a nocturnal visit to the local church roof before getting airborne!

 

A thrust line problem usually manifests as changes in pitch as the throttle setting is changed.

 

What sort of elevator movements have you set?   Does it pitch up violently as well?

 

A Puppeteer  should be pretty docile with the standard settings.  Have you checked theres nothing loose on the airframe?

 

Are the controls binding at all?

 

If you're using a computer transmitter, have you accidentally set positive exponential ...or built some into the control geometry?

 

P.S. Perhaps the poor thing is trying to shake the electric motor out and get you to put a proper 4 stroke engine in it's place!!! 

[Contact]

I think Andrew is saying that some of his models are on 35MHz and some on 2.4 GHz using a different RF module in his transmitter as appropriate.

 

I assume that the model memory is common so if he has flown a 2.4GHz model with the default setting of  PCM and then swapped to a 35 MHz model after switching the module (I'd imagine hot-swapping is not supported) which uses a PPM receiver and is programmed as such,  then unless he power cycles the transmitter after selecting the new model, it will still be using PCM modulation.

[Back copy RCME wanted, April 2003 for Kestrel plan]

PM sent

[Great looking model that....]

I suspect it might be available as a back issue?  David Ashby will probably be able to advise you if it is...

[The new site]

Yes - but only when using IE6 at work - not an issue with Firefox.

[Great looking model that....]

Thanks for the kind words...

The rotors certainly do spin but they will also (rather worryingly until you get used to it) stop in flight as the speed increases.  It has been described, by watching clubmates, as a flying lobster!

 

This is a well known design (the Kestrel) by Cyril Carr which was published as a free RCM&E plan in April 2003.

Above is a hastily knocked up composite because none of the flying images I've got are any good!

[The Model Pilot thread]

I also have a pilot who takes an active part in fling the model.  According to the designer,  Nigel Hawes, he's called Kevin and is an all-flying bat!

 

[The Model Pilot thread]

How about looking for the oldest active pilot? 

To get the ball rolling, my offering is an old chap who first took to the skies in a rather ill-fated Hurricane that I built in 1975. He's currently unemployed (awaiting a suitable model) and he last flew a couple of years ago in a Ripmax Gambler.