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Member postings for PeterF

Here is a list of all the postings PeterF has made in our forums. Click on a thread name to jump to the thread.

Thread: Peterf's 1/4 scale Falcon Models Tiger Moth
31/01/2016 18:01:58

Completed the control wires for the elevator. I have made the guide rod for the upper control wire from scratch, including a shackle from plate to closer match the full size plane I am modelling. The whole system works very well. This now takes me to the end of the fuselage build in the instructions. All that is left is to add a lot of scale detail and cover it. Before that happens I need some wings.

Elevator control wires and guide rods.dsc04028.jpg

Elevator up.dsc04030.jpg

Elevator down.dsc04033.jpg

Thread: Flair Taube information needed
31/01/2016 08:43:36

Chris,

The control throws are 50mm in each direction for the rudder and 15mm in each direction for the elevator. These are the throws I have had on mine since I built it 10 years or so back and have been fine.

I have added a bit of the plan below to show how the CoG is defined, 152mm back from the front of F5, which is the front former built into the wing section, i.e. the front fuselage / wing joint. I have recently measured my CoG as I have swapped to electric and I am flying with it 140mm back from F5 so my CoG is a little bit forward. When I originally built the model it balanced a little forward as my engine was a 40 4 stroke and a little heavier than the recommended one. At first I put some lead on the back of the fuselage for test flights at the 152mm CoG and it flew OK. I gradually took the lead off over a few flights and it flies fine balanced a little forward. I have kept the same 140mm position with the new electric motor and battery installation.

The one thing I did do that was not on the plan was to add bracing wires from the top and bottom of the fin post to the back of the tail plane. I found that the tailplane as flexible and when you pulled full elevator it actually bent the tailplane down, which was more effective at diving the plane than the elevator was at climbing it. It cost me a nose area rebuild to find that out. The bracing wires are shown in a couple of the photos. The photo was taken before the bracing wires were added in original IC configuration. I am not the only person to find that these wires are a great help, there are others I have discussed this with who have independently found the need for them. It is not always needed, I guess depending on the stiffness of the balsa in the tail plane. I would recommend that you think about this.

Peter.

a5416418-72-p5050011.jpg

dsc04015 (custom).jpg

dsc04018 (custom).jpg

dsc04023 (custom).jpg

31/01/2016 07:26:23

Chris,

I missed your original post as I was away before Christmas. I have the Flair Taube, I will dig out my plans and reply with the info later.

a5416419-84-pic-003.jpg

Thread: Peterf's 1/4 scale Falcon Models Tiger Moth
30/01/2016 07:29:33

That was a neat idea - not sure how the post got orphaned though.

Posted by ron thornhill on 29/01/2016 13:18:41:

Hi Peter just thought you may be interested with what I did with the turn buckles. I bought two lots, one with eyes and one lot open ended then swaped one end of each making easier to fit on with just a split pin. Your thimbles look brilliant, didn't think of that, too late now.img_3759.jpg

 
29/01/2016 07:26:13

Manish,

I had looked at those from the ship modelling site but the one type did not look the part even though they had then at 0.8mm ID, and the better looking ones may have been to large. My issue was the turnbuckles only had a 1.5mm ID hole so I could not accept anything larger, so making my own guaranteed a fit. I chose brass tube because you can usually get it in thinner wall than copper. I also looked on the ship modelling site for the shackles as I need them for the upper elevator guide rod, but looking at the full scale of the plane I am modelling showed that it had a shackle made from plate not bar, so I will make my own for that.

Peter.

28/01/2016 06:59:29

This is the photo of the completed thimbles after the long side had been trimmed, I accidentally used the same one twice in the post above.dsc03991.jpg

27/01/2016 22:20:13

The full size model has thimbles in the loops on the control cables to stop the cables wearing as they rub within the fittings on the control horns. The kit does not include anything and is set up for you to just bend the wire through the fittings. In an attempt to add some scale details I have made up my own thimbles, a few hours work to make the 16 required for the model. The cabling supplied in the kit is about 0.7mm diameter. The holes in the fittings and turnbuckles are 1.6mm. I sourced some 0.8mm ID x 1.5mm OD brass tube, 3 pieces 300mm long being plenty.

I filed a small slot in some hard balsa to rest the brass tube in. I put some soft steel wire around 0.6mm diameter through the brass tube, placed the brass tube in slot in the balsa and filed the top half of the brass tube away using an ordinary metal working file. I lifted the soft steel wire from the tube and then ran a small triangular file down the slot left in the brass tube to clean it up. The steel wire is put in the middle to give the file something to work the brass tube against and to file it completely away. The first attempt did not sue the wire and as the top oif the brass tube thinned down it deformed inwards making life difficult.

The next stage was to bend the end of the brass tube around a 3mm steel bar in the vice. I found that I did not need to anneal the brass tube. However, I did hold some steel cable in the slot to try and help keep it formed. I found that I needed to hold around 1cm of straight length on the one side to keep the bend formed well.

However, I only needed about 5mm straight length for the thimbles, so I made a jig up from some scrap ply to cut off the bent section at the right place. This left me with thimbles with uneven legs, so I then had to cut the longer leg down to suit the required 5mm length, again using the ply jig. In the end I used one complete 300mm length and about 50mm from the second tube.

The previous post shows them being installed. They can not be completely bent together until they have been installed.

Brass tube with steel wire inside in slot in balsa ready for filing downdsc03979.jpg

Brass tube filed down, steel wire visibledsc03982.jpg

Brass half tube cleaned up ready for bendingdsc03985.jpg

End of half tube bent to form the thimbledsc03986.jpg

Collection of uneven thimblesdsc03989.jpg

Collection of completed thimblesdsc03989.jpg

Close up of a completed thimble before installationdsc03998.jpg

27/01/2016 22:02:14

I have finally got back to the build and have decided to tackle the control cables for the rudder and elevator, rudder first. I made up some thimbles to go through the loops in the wires. I’ll cover making the thimbles in the following post. Pictures show the fittings made up from sheet brass, these were in the kit of parts from Falcon, just needing to be folded around the bolt. I have also soldered the two halves together to stop them opening up. For the adjustment of the rudder cables I have a set of 4 very nice turnbuckles from Mick Reeves, not perfect scale but will look OK on the model. I am still waiting to get the right bolts to attach them to the brass fittings, slight oversight on my part. Once everything was attached, a quick check with the Rx connected to the rudder servo showed the correct 2.5” displacement on the rudder. I had already worked out the geometry and chosen the hole on the servo arm and the APE settings on the Tx to get the right movement and for once, I got it right.

Rear control arm, brass fitting and thimblesdsc03999.jpg

Rudder bar, brass fitting, turnbuckles and thimblesdsc04001.jpg

Cables connected to the rudderdsc04007.jpg

Cables connected to the rudder bardsc04004.jpg

Rudder works, turn rightdsc04011.jpg

And turn leftdsc04012.jpg

Thread: Forum members' new models: Let's see them.
18/01/2016 20:22:19

Here is my Christmas present all assembled and now waiting for that elusive first thermal. This is the 3.0m span Gracia from Topmodel in the Czech Republic. Straightforward assembly, the wings are very nicely put together. The motor is one of the GliderDrive models from HobbyKing, an outrunner inside an outer can with rear exit bullet connectors so no wire to rub inside a narrow nose. I am glad I did not go for the 3.5m span version, room is tight in the workshop with the one I do have.

dsc03971.jpg

Thread: EDF exhaust tubes - why?
13/01/2016 08:41:50

Simon,

A proper link to my test page **LINK**

One thing I realised is that I did some extra tests with a parallel duct the same diameter as the fan, hence the exit area was essentially 127% of FSA, velocity reduced, there was some pressure recovery and the load on the fan reduced. The overall thrust was lower so was the power draw and the efficiency was also down. I also looked at an obround (obround = oblong with rounded ends) exit to the duct with 100% FSA as the model I was building needed that shape of duct (B2 Stealth). See photo showing obround duct.

In terms of the blunt end created by a motor, the air behind this will form a recirculation pattern and the jet of air from the annulus will gradually close in. There will be in effect a cone shaped back flow area and in an ideal world the cone will close in at an angle of around 10 degree. This means that ideally, the duct you add should close in at a similar angle so that you maintain a more uniform flow if you have a 100% FSA outlet, see sketch.

A cone with a small angle will create a lower pressure loss than a more abrupt angle. In fluid flow we normally aim for 30 degree or less for very low pressure loss. Also, if we have a non uniform flow and wish to have enough pipe to end up back at a more uniform flow profile over the tube, we could use 10 pipe diameters, sometimes for a high accuracy flow meter we may use 50 pipe diameters or put flow straighteners in.

_exhaust test.jpg

dsc01500.jpg

edf duct.jpg

12/01/2016 22:36:21
I performed some tests on a Vasafan 55mm fan with different sized ducts. I measured static thrust and from basic fluid flow calcs determined the eflux velocity. This showed thrust peaked at 85% FSA (yes you do subtract hub area). As area of exit reduced, the back pressure on the fan increased, reducing the mass flow, but the velocity increase outweighed this up to 85%. As the duct got smaller, the mass flow reduced more quickly than the increase in velocity. Fans can not create a very high pressure increase before the flow falls right off. You can find the work in the last post at http://www.rcgroups.com/forums/showthread.php?t=1549178&highlight=Vasa+55&page=3 Sorry my tablet does not show the proper link method, please copy and paste.

Edited By PeterF on 12/01/2016 22:37:29

Thread: Did Santa bring you anything nice ?
27/12/2015 19:48:28

Topmodel Gracia electric glider. I found out how big 3.07m wingspan really is when I laid out the wing panels on the kitchen worktop. Beautifully built kit. Looking forward to getting it assembled but no rush with the current lack of thermals.

topmodelcz gracia ep 3.07m 1.jpg

In return SWMBO got a combined scanner and cutter for her craft and card making hobby. When she demoed that I just happened to drop into the conversation "So, would that be able to cut self adhesive vinyl such as could be used for lettering and decals on model planes?".

Thread: Which kind of models can be flown at your site?
14/12/2015 18:39:52
Posted by Vecchio Austriaco on 14/12/2015 18:10:15:

An anything but jets option would be useful for some of us - me included. so I will point to anything in the poll - as 61 is not a real big engine size.

VA

Same thing here, we fly up to perhaps 50cc petrol, 200 glow but not jets.

Thread: Autumn is here!!.....Who's been flying??
13/12/2015 21:21:07
Posted by Erfolg on 13/12/2015 20:14:15:

A good day up here in the Northern powerhouse, very, very, slight drizzle, at times.

I flewcheeky

Same here on Teesside, out for a few hours this afternoon, only 2 of us at the field so lots of batteries got discharged.

Thread: Problem with tape hinged ailerons
08/12/2015 19:52:35

Have you taped both the top and bottom surfaces of the joint, although if there is some stretch in the tape or gap between wing and aileron then this will not help much. Sorry if I am doing a granny and eggs thing.

Thread: I.C. or Electric? - New Poll
06/12/2015 15:25:59

There is one loss that i have noted now I have converted my fleet to all electric and that is ambience created by sound in one specific case. My Etrich Taube had an OS 40 4 stroke, too big really as it will fly on a 25, but it meant that I could over prop it and when flying in a scale manner it just burbled along on 25 to 30% throttle sight and sound coming together. I miss that and I took a bit of stick for it from the judges / critics sat in the pits.

06/12/2015 09:47:34
Posted by Solly on 06/12/2015 09:27:52:
Posted by Electric God on 06/12/2015 08:29:25:

 

At the end of the day , it won't be us that decide the future but legislation.

Fossil fuel technology is going the way of the horse drawn carriage and steam engine.

Noise from electrics ? it's practically silent compared to a ic. No comparison in my books .

Good luck to those that love there old skool ic but don't surprised if the end is closer than you think .

I was amused to see that you think methanol is produced using fossil fuel technology. In fact modern methanol is manufactured using a catalytic process directly from carbon monoxide, carbon dioxide and hydrogen. No fossil fuels in sight.

 

Solly,

I am afraid methanol is made from fossil fuels, I am a chemical engineer who designs methanol production plants, the last one I worked on made 3,600 tonne per day of the stuff, the current one in design 5,000 tonne per day. Natural gas in huge quantities is reacted with steam at high pressure and temperature requiring large high temperature furnaces and boilers and huge compressors using lots of natural gas fuel to produce the carbon oxides and hydrogen (synthesis gas) which is then used to make the methanol. In china they make the synthesis gas by reacting coal with steam and high pressure oxygen. I know this is a simplistic overview, it is not a discourse on all methanol production methods.

I am always troubled that I know the people to buy methanol from at less than £1 a gallon but you need to order in bulk, I.e. say a delivery of 50,000 tonnes compared to the street price.

Edited By PeterF on 06/12/2015 09:51:59

04/12/2015 07:06:28
Posted by Geoff Sleath on 03/12/2015 22:46:21:
Posted by Dane Crosby on 03/12/2015 11:29:46:

Shouldn't jets/turbines have a separate vote?

Gas turbines are internal combustion (ic) engines. It's just that the suck, squeeze, bang, blow cycles happen concurrently.

Geoff

or as us chemical engineers would say, it is a continuos process rather than a batch process

Thread: How far do you fly??
02/12/2015 19:38:42

Oh, and there was the time a pupil's 8 foot span trainer decided to ignore all inputs and went off downwind in a climbing spiral - it got to the point where all that could be discerned was a flash of sunlight from the wings every revolution...never to be seen or heard of (thankfully!?!?) again.)

We had one like that, last seen heading off over the North Sea.

I have just looked at the Eagle Tree data for my 2.5m electric glider, no trouble 600m away at 320m above ground level, probably benn further and higher, nearly lost sight in a thermal once but did not have the logger on board that day.

Edited By PeterF on 02/12/2015 19:47:42

Thread: I.C. or Electric? - New Poll
02/12/2015 19:36:46

Gone all electric, I gradually drifted to the point where all my small scale / sport / F3A / gliders were electric and had stopped taking my larger scale planes to the field anymore, which was a great pity, so I bit the bullet as it where and converted everything over and have not looked back. One thingi have tried is as best as possible to keep to a small number of battery types comon yo many models in your fleet. This reduces the overall outlay and also means that if you do not take one particular model flying for a while, you do not have batteries sat around unused. 10 models rangeing from a Ripmax Spitfire through to a 1/4 scale tiger moth use two battery types.

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