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Everything posted by PeterF
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A foam is a 2 phase material with a gas dispersed in a solid or liquid. If the solid is elastic then you have "sponge", if it is more rigid you have the types of foam used in RC aircraft. I even used metal foams when I worked.
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Peterf's 82" A-10 Warthog plan build
PeterF replied to PeterF's topic in Build Blogs and Kit Reviews
Chris Golds produced a 62.5" plan which Sarik Hobbies supply a kit for ( Chris Golds A-10 ). I thought that scaling this from 62 to 82" was probably a bit much. -
I have not done a substantive build since 2019 / 2020 and had lost the itch a bit. I had built a couple of models in the interim, but not what I would call substantive. I found myself with a bunch of equipment for a twin EDF build with a pair of high power 90mm fans on 8S that put out around 3kW each and a total 9kg (20lbs) of thrust for the pair. These have proven to be well capable of powering a 25lb slower flying EDF. I decided that IN would prefer to stay with a slower flying model rather than using them in a fighter type plane and for this reason I have chosen the A-10 Warthog. I cast around for plans in the region of 80" wingspan and came up with a set of plans on Outerzone for a model by George Miller from the USA, scaled at 77.5" wingspan. This plan was from 1985 and was based on a pair of 127mm (5") IC ducted fans driven by 46 sized engines. By all accounts it flew well as long as the engines remained working, but was a heavy beast as it needed a lot of lead in the nose to offset the rear mounted fans and fuel tanks which had to be close to the engines. I chose to increase the plans to 106% to get to 82" wingspan for a couple of reasons. The first was Roban used to sell a model at this size (the Roban model was slated as being poor with a reputation for wing folding in flight and collapsing retracts). JP Hobby sell a set of quality retracts for the Roban model so I could purchase a set of these and use them. Secondly, I believe I have the power for the weight of plane at this scale and a lot of the weight will not vary from 77.5" to 82", batteries, motors, ESCs, servos, retracts etc remain the same so I would reduce the wing loading slightly. I also have a feeling that I should be able to do this with hopefully a lower weight. There will be less weight in the engine pods and the batteries can go in the forward fuselage as a counter balance so there should be no need for 2 to 3 lbs of lead in the nose. I am also lightening some of the wood in the engine nacelles as they will not have as much vibration or mass to contend with. I used PDF scaling software to increase the plan by 6% and sent the files off to be printed by an on line service using a plotter and rolling the plans, printed on technical grade paper. The plans have come out well, however, as a warning, if anyone is inspired by this, the original scanning of the plans was not perfect and there has been some distortion of the plans. For example, some of the formers are slightly lozenged, double check everything before cutting. In addition, with this type of build you need to be experienced in plan building, you are on your own in terms of fan installation, retract installation, power system location etc. There is no build article or notes to go with the plan. Whilst there is a company in the USA that still sells laser cut kits and fibreglass components, once I decided to go to larger than plan, I am on my own for all items like this. The fuselage sides and bottom are 1/4 sheet balsa with some ply doublers around the wing opening. Most of the formers are 1/4 balsa sheet apart from the engine nacelle formers which are 1/4" birch ply in the plan, but have been swapped to light ply for my EDF build. The fan bearers will remain as birch ply. The fuselage is starting to take shape. It really is a simple shape and lends itself to the simple design in the plans. Photo of a model from many years ago. Cutting out formers. First stage after gluing the sides and mid section formers. These formers all have the same width, making this stage easy. Glued in with PVA, tacked with cyano. Also shown is one reason for getting the winter modelling mojo back, the diesel heater, makes building at this time of year much more pleasant. Gluing the formers for the engine pods together as a single unit with the fan bearers. These are in position in the fuselage but not being glued in at this time. The fuselage starts to taper in here making lining the formers up a bit trickier. The ply doublers over the wing openings can be seen. The wing openings will be cut out later. These formers and fan bearers were glued with 30min epoxy. The front 2 formers whilst being light ply are better quality with 5 layers and are denser than the lightest light ply, the fan sits between these. The rear former only supports the exhaust tube and is light light ply with only 3 layers. Engine pod, rear and front formers being installed. The bottom sheeting template can be seen by the side of the fuselage on the bottom sheeting. Fuselage sides with formers installed ready for the bottom sheet.
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BBC news article. Plenty of other articles on line from yesterday evening. Teesside Live article (full of adverts).
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tony nijhuis Nijhuis Lancaster 1/9 scale
PeterF replied to cymaz's topic in Build Blogs and Kit Reviews
The plan elevators is I believe because the early Lancaster had fabric covered elevators so doing it the way of the plan gives some stiffness from sheeting but shows the starved horse effect of fabric covering where it can be seen. Later Lancasters had sheeted elevators. The TopFlite DC3 I built was like this. -
Similar in Peter Miller's book "Designing Model Aircraft". If you have ever built a plan by Chris Golds or built a Tony Nijhuis kit like his large Vulcan then the ribs in these are basically a web of lightening holes surrounded by precious little wood.
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See this page, gives some background to these. http://www.flyingsites.co.uk/news/flairnews.htm
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I have a temporary enclosure made from 2mm MDF shhets that I put around my 3D printer when printing ASA. I went to ASA after learning on PLA and PETG and have also printed in TPU. I have printed parts in all 4 filaments for RC planes including a complete Stearman in PLA before PLA-LW came out. The only issue I have had is the PLA nose cone on my Vulcan distorting when I left it too long in the back of the car with the sun shining on it through the curved tailgate glass. I have some bits printed in both black and white ASA on the outside of my boat (full size not RC) that have been permanently outside now for 4 years with no sign of degradation. None of my Tiger Moth was printed as I bought the printer after I completed that.
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Unilight of Austria do a good range with some parts that may do the bill. They also kit sets for various models including a 1/4 scale FW190. Have a look at the links below. Nexus Modelling Supplies sell them in the UK. I have just bought some of these for a 2m A-10 Warthog but they have not arrived yet so I can not comment any further. Unilight 1/4 kit for the FW190
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We need to recognise that RC planes absolutely thrash lithium batteries harder than any other use, be it cqrs, phones, power tools, computers etc. There is no other service where we take the batteries from full to 20-30% in 10 minutes or under. No wonder we are happy with 300 cycles. Most lithium battery users are looking at 5,000 plus cycles at normal usage where the discharge occurs over many hours not minutes.
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Steady on here, often retailers quote the boxed weight if it is being posted and that will include the Tx.
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1/4 Scale Tiger Moth build, a work very much in progress
PeterF replied to Richard Thornton 2's topic in Scale Matters
Can't help you on this one, I painted all my wooden structure before painting, then coveted with natural solartex then painted the outside. The only covering that can be seen from the inside is black and my build photos show this. I do not know what the prototype is like but my model being black is not an issue. What I have done at times in situations like this is with plastic handle paint brushes is to bend the handles (heat gun may help) to get an angle the the head, of for wooden ones cut them down then glue them back together at an angle.- 143 replies
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- tiger moth
- 1/4 scale
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I was in the same position with a plan of Miss Lizzy, got round to building it over winter electrified. Flew it again yesterday, a really nice model. See a couple of posts down at https://forums.modelflying.co.uk/index.php?/topic/24961-forum-members-new-models-lets-see-them/page/195/&tab=comments#elControls_996254_menu
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Looking at some pictures the movable mounts for the motor/prop combos look a bit flimsy. I know they will have been engineered and should be suitable. They will experience a mix of forces, torque from the prop rotation along with tension from prop thrust not to mention the gyroscopic forces when the props transition from hover to forward flight and back again and added in to that in hover the prop is forward of the hinge point.
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1/4 Scale Tiger Moth build, a work very much in progress
PeterF replied to Richard Thornton 2's topic in Scale Matters
Richard, hat off to you on this, I did think about going the chain route because that mimics the full size but could not find the parts. I am a little embarrassed now at not having worked through to this detail. I ended up with a wire breaking on the ground and swapping to low profile servos in the wings. Still flying the plane, last out a week ago and it still flies well and looks good.- 143 replies
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- tiger moth
- 1/4 scale
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March 2024 Issue - advice on replacing a Nimh RX pack with a Lipo
PeterF replied to leccyflyer's topic in RCM&E Magazine
Even if the UBEC is not drawing any current the device will still keep the output wires at the correct voltage so the voltage control and monitoring circuits will still be drawing current and there will be some leakage current through the power circuit creating a standby current draw. A 6 milliamp current draw over a week will flatten a 1000mAh battery. -
One thing I would suggest is to ask your examiner to demonstrate the A test to you. I am an area chief examiner and find this can be really helpful for both A and B candidates. It is one thing looking at videos and reading texts and trying to understand these, but if I fly what is required in front of them, they can see what is expected and there is no confusion.
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Thst sounds like much to much fan for a 2700mAh battery, that size battery is typically running 55mm fans, it.might do 2 55mm fans but not 2 70mm fans. I have a model with twin 70mm fans on 4S, it pulls 105A and I use a 62500mAh battery. Your may not be that high powered but as said above, you should always have a Watt meter to check.
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This is an outcome of fluid flow dynamics, for a specified thrust it takes less power to move a large mass of air slowly (prop) than a small mass of air rapidly (ducted fan).
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IIRC the government wanted to reduce it to 15%, held a consultation and got pushback from BMFA and probably the RC car fraternity and probably other users/ producers and it was set at 30% so ready mixed high nitro fuels did not get included. Can not remember the exact details.
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I am guessing you mean Tayna batteries and auto correct has changed it. They have a very good reputation.
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1/4 Scale Tiger Moth build, a work very much in progress
PeterF replied to Richard Thornton 2's topic in Scale Matters
Richard, I have been away for a few days and missed these recent updates. I am glad you have got back to your Moth. Excellent modelling, puts some of my work in the shade, especially the slats, I simply screwed mine in place. I look forward to seeing your ongoing work and the plane flying.- 143 replies
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- tiger moth
- 1/4 scale
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(and 2 more)
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Spent a lifetime designing methanol production plants, they typically produce 3,000 to 6,000 tonnes per day, but the minimum order quantity needs a small tanker (ship tanker not lorry tanker) to collect it with if you order direct.
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I have had it once on a NiCad Rx set many years ago. Someone recommended running a dehumidifier in my garage workshop to keep it drier, only run it for 2-3 hours twice a day. I have not had black wire since then, but not sure if that is due to the dehumidifier or the move away from NiCad Rx batteries.