Veron Chilton DW1

Quorneng wrote: There is another reason Co2 is used as when it is compressed above 75 psi at room temperature it becomes a liquid! Those little bottles are actually full of liquid CO2. This means that even though gas is being released it will maintain a constant 75 psi until all the liquid in the bottle has 'boiled off'.

That's nearly correct Quorn - it will liquefy at 75psi but only at about -78 Celcius. At room temp, you need more like 700-1100 psi (5 - 30 Celcius). Not meaning to be disrespectful in any way.

But, while I'm being technical - density of the gas is about 2/3 more than air, so about .002 g/cm3. Compress that to a liquid at about 20 Celcius (60 times denser or about 900 psi), density becomes .12 g/cm3. Then we can work out that a 3 cm3 tank will have about .36g of CO2 in when full and make a judgement if that will affect CG position between full/empty. It feels fairly insignificant compared to the weight of the motor/tank combo which iirc is 15-20g for a Telco.

I have recently had to measure old Sparklet bulbs that are still sealed to see if there's anything left in them (they get rusty and can wreck the charger seal on the neck). The difference is about 2-3g between full and empty which should tally with getting about 4 liquid charges per bulb.
Hope that helps someone - the science is easy, building those small models is the hard part!
Nigel

My goodness, who would have thought about all that tech and development when adding a splash of soda to their evening tipple from a shwepps soda fountain in the 1970s.
Thank you for your educational reply. Boz

Thanks Nigel for a comprehensive reply.

So my Sodastream bottle contains 425g of CO2 when full at 0.36 g per liquid charge thats about 1,100 Telco tank fulls per bottle. Many of my CO2 motors are much bigger though with 6cc (?) tanks like the GM300 but that would still give around 500+ refills per bottle. No wonder they last so long.

Rainy day down here in the Chilterns so ideal opportunity to get some more down on the little Chiltern .

Its a nice design from Phil Smith which builds very quickly






As ever with CO2 installations I'm having to build it in to the model. I've pushed the tank back to just in front of the CG, any further back and it'll be in the cockpit. The engine firewall is yet to be made but I am thinking that I will add some thrust settings into it as I build it.

I was thinking 2 deg down and 2 deg R thrust .. Thoughts ????

The engine will bolted in with 12ba machine screws with captive fittings (epoxied nuts to the firewall - which coincidently sounds rather painful !) so I can alter the thrust when trimming. The nose fairing can then be held on with a magnet

What a sweet little aeroplane. I corresponded a bit with Phil when I used to do a column for SAM35 Speaks and met him once (or was it twice?) at OW - great guy

Mike

I think he's very much part of our modelling history now, I met him once at Middle Wallop , we both had an interest in Col C E Bowdens designs. I did not realise that that Phil actually knew C E Bowden very well until that meeting, nor did I realise at the time the small scale model kits I made as a kid were designed by him !!! a legend

Squirrelnet wrote: I think he's very much part of our modelling history now, I met him once at Middle Wallop , we both had an interest in Col C E Bowdens designs. I did not realise that that Phil actually knew C E Bowden very well until that meeting, nor did I realise at the time the small scale model kits I made as a kid were designed by him !!! a legend

absolutely
Mike

Squirrelnet wrote: .....As ever with CO2 installations I'm having to build it in to the model. I've pushed the tank back to just in front of the CG, any further back and it'll be in the cockpit. The engine firewall is yet to be made but I am thinking that I will add some thrust settings into it as I build it.

I was thinking 2 deg down and 2 deg R thrust .. Thoughts ???? .....

I would go for 5 degrees right and 5 degrees down Chris. I'd also make sure that the prop driver is on the fuselage centreline, which will make the engine mounting off-set to the left and high. The flight trim in this case would be left-left.

Thanks Andy I will go for 5 deg down and 5 deg right, left left is what I need

Late start at work today so managed to use the time

Dec2014 RC Model Flyer mag had an article about the Chiltern monoplane in detail.It may be useful to you. £ 4.30 for the copy

Squirrelnet wrote: The engine will bolted in with 12ba machine screws with captive fittings (epoxied nuts to the firewall - which coincidently sounds rather painful !) so I can alter the thrust when trimming. The nose fairing can then be held on with a magnet

Confess I was guessing at 3cc, sounded familiar from somewhere. The Gasparin W Anzari instructions I have says it takes two sparklets to fill.
Might I suggest making two cowls, one with a big hole to allow thrust angle changes but weighing the same as the other which can start blank until you have the trim sorted? My Pussmoth has a very eccentric orifice ...
Love those little pin hold-downs you're using, can I ask where you came by them?
Waiting to see your covering technique, not that I'm going to copy or anything I've been reading lots f tips from old masters on the free flight.org/library link Andy S provided elsewhere. Lots...
N

Knew there as something else... I was just planning on winding the motor mounting screws in to fairly thick (3mm) lightply. So long as they are fairly tight I expect them to hold. Pussmoth has self tappers but the Bomber will use machine screws. A bit of thin cyano will firm up the wood if necessary. Will let you know if it turns out I need glued nuts instead
N

Glued nuts!!

Glued nuts!!

I always glue my nuts

Having to work this weekend So not much chance to do anything more on this but at least I've managed to get the undercarriage fitted so it looks a bit more like it should

looking lovely sire.
not sure about the whisky still in the cockpit area, i dont think a drunk pilot would be a good idea.



Tony B