Robert Hynes

I liked this Matty. Particularly the link. Thanks for posting.

Hi Matty, thanks for this. As requested I have removed your name from the credits but thank you for your input none the less. While we have a strong safety warning in the article itself and a very strong generic safety disclaimer on the home page of the website, we feel on reflection this can be further enhanced after reading your suggestion above, so many thanks for taking the time to write it.

Hi Bryan and Matty, your inputs have been valuable in writing this AeroBase article. The interesting thing for me is your different viewpoints. Your concern Bryan with all things safety mirrors my own but Matty's viewpoint although different is also valid. This left me with a problem of how to adjust the article while addressing both viewpoints. I've tried to accomplish this by adding section 6, What can go wrong and how to avoid it. This seeks to address your concerns Bryan. In addition to this, for every point in the list I have added a risk assessment so that the reader can have some idea of the likelyhood of the problem occurring. This seeks to address your differing viewpoint Matty. I believe the article now covers your points but please remember all AeroBase articles are dynamic, and they can be changed at any time by comments from registered users or via resources like The Model Flying Forum, as in this case. Many thanks for your help with these inputs. Bob Hynes.

Hi Bryan and Matty, What is clear from your responses to the AeroBase article is there are differing viewpoints in terms of the risk of damaging balance leads and associated circuitry when running the parallel charge process. The AeroBase article handles this important point by stressing the absolute need to have the battery packs in an equal state of charge before the charging process begins and explains the point in detail in Step 1 of the Process Table. Step What How Detail Why 1. Equalise the charge level of the LiPo packs to be charged on the paraboard. Connect the power leads of the LiPos to the paraboard only, leaving the balance connectors disconnected. This parallel connection of power leads allows equalisation currents to flow between the packs as the battery packs with higher levels of charge transfer that charge to the packs which have lower levels of charge. This process is automatic and self regulating and benign as the currents, (amperes), which flow are well within the packs current limits. While the initial currents which flow in this part of the process can be somewhat high depending on the difference in charge level, they quickly reduce in magnitude as equalisation proceeds. This ensures that charge transfer does not pass through the LiPo pack balance leads which are designed for low currents only and initial charge equalisation currents could exceed their ratings. While it is true that parallel charging without using the balance leads does work, (provided your charger allows it), bypassing modern digital charger’s safety algorithms by so doing, is not ideal I feel. Further what is clear in video 3 in the Aerobase article is that parallel charging with balance leads connected does work really well, is safe and at 1C generates no heat whatever. This is not new of course, i.e. the video merely confirms this is the case. All that said the anxiety expressed over the balance leads and their circuitry could be discussed in further detail in the article to ease such fears. I will do that soon. Meanwhile thanks for the input. I will credit you both for highlighting the point in the Revision History of the article after I make the additions.

Hi Bryan and Matty, many thanks for this quick response. Your points are very interesting and will be fully addressed in the article shortly. I will wait a while and first see the full response in case there is more and then address things directly in the AeroBase article crediting you both for your input. Many thanks for taking the time to write. This is delightful for me to read, for it is exactly how AeroBase is supposed to work. Bob.

Hi Mike, I thought you would like to know that the AeroBase article on parallel charging LiPos is complete and you can read it in PRE RELEASE state at this link http://rcaerobase.ipjdev.co.uk/index.php/in-flight/106-method-and-risks-of-parallel-charging-lipo-battery-packs It's important to add that none of your text or photographs or tables are copied as that would infringe copyright. The Aerobase article, although inspired by your RCM&E article, stands on it's own and has several distinct differences and any comments you might have on it would be greatly appreciated. By the way it might be worth adding that AeroBase registered users get updates via email when new articles are pre released. This allows registered users to get their comments in early, all leading to improved records before full release. Finally I would like to say a special thank you for this idea. I now parallel charge my LiPos exclusively and am considering buying a large dc power supply to power all my chargers at once. My goal is to be able to parallel charge all my LiPos in under one hour. Brilliant. With kind regards, Bob.

I believe you have a very valid point Matty and it is one that I will cover in detail in AeroBase in February. To preempt that slightly, 1. Safety is paramount and 2. Parallel charging is definitely not for everybody.

Just wanted to say thanks to Mike Freeman for this article on parallel charging. As a result of reading it I went straight out and bought two paraboards and will be buying more. I particularly enjoyed the detail in the article and the technical account of the risks. I currently have three electric aircraft with four LiPos each. The fact that I can now charge all twelve packs in less than an hour will change my life. I do agree that safety is paramount and will be writing a reference article in Aerobase in the near future crediting your article as the source Mike. When that is finished I will post a link to a new thread on the ModelFlyingForum here for input. Again thanks, I really enjoyed the article. Bob Hynes.

Hi Pete, thanks for this. Although I tend to write my own, I took a look at the site. They've been busy there. As for the software in question, I am still working on it and will post it here should we get a good outcome currently looking promising. Bob.

Dear John, My programming language of choice is Excel. The need to translate code from Excel to VB comes from the need to make software solutions accessible to non tech. Aeromodellers, who often freeze at a Excel page with inputs and outputs. To demonstrate what I mean, I will private message you after this with my email. If you are able to respond, I will forward you my Excel solution to Neutral Point, which I use routinely to establish Static Margin before maidening any of my aircraft. The program is already pointed to in RCAerobase but is only available via Dropbox, which is not ideal. If you do get to look at the code my question is: What additional steps could be taken to make the code totally user friendly in Excel, as that would be far better from my perspective than a complete rewrite in VB. I should add I can tell you are a programmer from your response. Thanks in advance. Bob.

Hi Everyone, closing this thread now, with thanks to Plummet and Wolston Flyer for finding two separate solutions to my VB problem. Many thanks, Bob.

Hi Everyone, In case I might get lucky. I am trying to convert a piece of aerodynamics software from Microsoft Excel to Microsoft Visual Basic. While Microsoft imply earlier versions of VB are free to download, there are problems in that software registration numbers are needed to keep the software functional for more than 28 days. If anybody knows how to defeat this problem, so that the software once installed remains active I would love to hear from you. I couldn't find an ideal topic in the pull down for this, hence the All Things Flying selection, so if the query can be better placed I would appreciate help with that. Thanks in advance, Bob Hynes.

Thanks Pete, doing it now.

Hi Allan, I don't know whether this will reach you as I believe your email is out of action but just in case. We are still trying to reach you regarding the problem you are having with the front page of RCAerobase but find the email address you gave us is no longer working. If you pick this up please get in touch so we can help. News my end is I've moved on a bit since we last talked of magnetic building systems and am currently building magnetic squares to enable me to jig build my fuselages, so I'm closer to having a fully functioning magnetic system. So, fingers crossed you are still out there and that you pick this up.. Kind regards, Bob Hynes. (RCAerobase)

Hi Dave, to be sure I understand this, I believe you are saying: 1. The RC installation works well with flying surfaces obeying transmitter commands correctly but...... 2. After giving any Tx command and returning the controls to neutral, all axes, e.g. rudder, elevator, aileron, throttle, jitter or flutter, (rapid oscillatory movements of the servo output shaft), for a few seconds before settling down at their neutral positions. If this fault description is correct, the issue electromagnetic noise, which is often seen with digital servos but rarely if ever with the earlier analoge types and is dealt with on RCAeroBase here: http://rcaerobase.ipjdev.co.uk/index.php/radio/radio-servos/87-control-surface-jitter-problem The specific points being 7a, and/or 7b If you think this may be the issue, then a quick test would be to remove the digital servos and add a test analogue servo. If the jitter stops, then the test has identified the the digital servos as the noise source which is getting into the Rx input citcuitry and being falsely recognised as servo commands. If the description is incorrect there are other solutions to other causes.

I'd like to second BEB and PB's comments and add that elevator trim can also help. This can facilitate the best take off run with mains firmly on the deck so that the aircraft rolls with tailplane off the ground If you get this level of trim correct the aeroplane will need slight up elevator to lift off and and this will need to be maintained for the climb out. If done optimally it takes all the pressure out of the takeoff run. The advantage is you get ground speed above the stall before lift off, making a wing drop unlikely, (see below), after lift off, after which the aircraft continues to accelerate to normal air speed. If you are not comfortable with using different elevator trim settings during flights then do practice first using something like the Phoenix flight simulator. If you overdo the down trim and take your thumb off the elevator as soon as as you lift off you will likely pile in, so take care, again you can duplicate this with the sim. Just enough down trim to make it easy to give you that long accelerating take off run. The only other situation I have seen with an unexpected roll at lift off was caused by a wing warp. The reason here is that in flight the warp could be effectively tuned out using aileron offset. Ailerons are much less effective at liftoff however and so the aircraft rolled on takeoff with the warp. Cure of course was to fix the warp.

I’ve just abandoned a new JEN 37 engine because of endless difficulties which I have not seen on any of the other model aero engines I’ve used over many years and wanted to detail the problems here so that other possible users may be aware. The engine performed OK at first but then started to cut out in flight and so I persevered but without success. Eventually, at my wits end, I stripped the engine down and discovered what turned out to be a known factory fault as follows: The gudgeon pin is retained by a teflon pad which in my case was either never fitted or came out in use as the teflon pad passes an open fuel inlet port thereby allowing egress should it become loose or dislodged. As a result of this the gudgeon pin migrated into the cylinder wall and gouged a 1-2 mm. groove in the liner which was the cause of the deterioration and which Just Engines Tech. Support explained was a known fault and occurs in approx. two out of every hundred engines produced. To my mind it’s clear the design is weak and that retention should either be by circlip or pads that do not see the light of day, i.e. which see cylinder liner for the whole of their travel. Just Engines said they would repair the engine as it was still under warranty. I found that odd as I would have thought they would have wanted to repair it regardless of warranty given it’s a known fault. I returned the engine. Chasing the repair some weeks later I was told warranty was voided, which I already knew but had understood the repair would proceed given the known factory fault. The upside was, JE went on to say, that they had repaired the engine using spares from an engine, (i.e. second hand parts), that had been returned to them for other reasons and had fitted a new piston ring which I would need to run in again, and would I send them the money for return postage. Again I ran the engine in and it seemed to be holding up but then started to stop in flight again. So I stripped the engine down again and found: 1. Teflon pad retainer canted at an angle of 20 degrees to the vertical, and loose. 2. Signs of blow back at the piston ring gap. The gap measures four thou across the cylinder liner travel which should be ok. But possibly isn’t. While Just Engines would look at the engine again it would need to be at my expense and without guarantees which is arguably reasonable given my strip downs. In conclusion I’m very glad for all those out using this engine range without problem. I myself however would not have another at any price. For me from this point it is ABC or nothing. Costs to me here are about £100 including postage and fuel and hours of frustration and effort. The upside is it’s in the bin, it will cost me no more and I am wiser.

David, I'd be very interested to hear how the aeroplane flew exactly, e.g. did it constantly pitch up and down so that elevator corrections were constantly needed?, was it for ever dropping a wing so that aileron corrections were needed? Without such data it's difficult to respond.

These are three interesting comments so many thanks. I will close my efforts with this short note. I have tried hard in what I have written, to make as clear as possible that I feel the forum is a good resource. I would hate to see it go but I am not sure I am believed and so I emphasise it for a final time. The forum is a great resource and should stay, forever. It's clear to me from what is written in response that the potential of a database of this kind is largely misunderstood, and while that is a shame, it's not the end of the world. The twenty or thirty usual suspects would make great authors. The phrase below, written by Chris Bott for me says it all. For me it's the best thing I've read in this thread, so thanks for writing it. On the other hand, a good indexing function that would help find existing answers in the plethora of information here would be useful, but probably impossible to make work, given the different words and phrases folk use to describe the same problems. I should close out now and so would like to say thank you once again for all your comments, Robert.

Hi Everyone, thanks for your posts on this thread. I am replying to them here by writing comments in brackets in copies of your posts below, to cover your individual points. Robert. Posting:Robert, Whats wrong with the current system on here, ( there is absolutely nothing wrong with the forum. I use it from time to time myself. If I had the choice however, I would always use a database and the reasons for this are stated in the thread.) if I have a question I simply ask it and somebody who knows the answer replies or directs me to another thread that contains the solution to my problem, ( yes of course, I know this and you are right, it works, just not efficiently.) normally quite rapidly & usually with a little light hearted banter thrown in for good measure! (Good though this is, it would never be as good as single authoritative documents that are easily findable, in my opinion. For me the real negatives to creating such a database resource are the effort needed to make it work and the time it would take to make the resource workable, i.e. you would need at least 100 records to make it worth visiting at all and that alone would take some considerble effort. It is worth adding however, if the idea is fundamentally bad, then why does anybody use databases anywhere, ever. The answer lies in their power. Their ability to be rapidly sorted, and effectively searched etc., etc)..Or try using the Search function at the top of the page! ( I don't feel I should reply to this although I do understand the nuance. That said I still enjoyed your reply.)Posted By chris basson on 25/03/2013 12:00:45. Posting:Hi Robert that would be one hell of a data base......( you are absolutely right Johnny. It would not be easy but it is possible), and thats just for the questions that I have asked in the past!! lol. Just taking your example above thats alot of typing for just one answer.... (I agree but the converse is that if the document is authoritative and allows input from readers which lead to edits and improvements in the given record, then the advantage is the user has ony one document to read on a given problem. This is why databases have the power they have. It should not seek to replace any establised fora, rather it should exist in parallel as a master resource.) As Chris says above there is nothing wrong with the current system and in many cases there is no black and white answer to the question beind asked. ( I doubt this, by which I mean that providing symptoms are expressed succinctly by key word fields, there will be a finite number of solutions, moreover for the core of problems experienced by aeromodellers in a generic sense, a finite number of records would address them, I believe.) personally find its best to pick the brains of the guys on here (and other forums) ..read the answers and then make my own mind up from there. (I know this works of course and the approach is fine but I would still argue argue against, respectfully, that as a user, you should not be having to make up your mind about any data you read or picking which forum response you believe is correct. You should rather know that the data you read is always absolutely valid, and you cannot do that with fora, good and worthwhile though they are.) If you fancy having a go at the data base I wish you well my friend.....good luck. (This is kind of you but I wouldn't dream of writing it myself, it needs buy in and judging by the responses so far I have to say I think it's a long shot.)

I wondered whether anyone has considered creating a Problem/Solution Database for aeromodellers. The reason I ask is that databases can be much more efficient than fora in zeroing in on specific data. To clarify this, whenever I need data and begin a search, if I go to a forum such as this one, I become anxious. The main reason is I know for sure I will waste time reading irrelevant material and there is a good possibility that I will not find the data I seek whether it is in the forum documents or not. A database solves this problem to a large extent. To be clear see the following example database record which I will just make up quickly here. ____________________________________________________ Aircraft Type: Fixed Wing Tail Dragger Symptom: Aircraft weaves from side to side during the take off run, and controlling this with rudder control is not effective, leading to damage to the aircraft Problem: 1. Wheelbase too wide. 2. Fin/rudder combination too small in area. 3. Offset wheel tracking. 4. A combination of all the above. Solution: 1. Reduce wheelbase. 2. Increase fin/rudder area. 3. Correct tracking, as needed. Expansion: 1. Engine torque on engines which rotate anticlockwise looking from the front place greater downward pressure on the port wheel. The added friction losses this creates causes the aircraft to swing to port. This motion creates angular momentum about the port main which the fin rudder combination can barely correct as the torque of that angular motion is proportional to the fourth power of the radius described between the C of G and the port wheel. Because of this fourth power effect, any reduction in wheelbase will make a dramatic improvement to the weaving/ground looping effect. See. PDF xxx See Video XXX Key words: Ground Loop, Weaving, etc. Author: XXX. _______________________________________________ A database such as this would be a very powerful tool allowing the aeromodeller to do the following: 1. Go to the database and find the needed data, quickly. 2. Go to the the database and establish the needed data is absent, quickly, 3. In the event of 2. above,, go to the database and request a new database record covering the needed data, quickly. 4. Go the database knowing there will be no duplication. 5. Go to the database knowing the data will always be sound and succinct. I would give my right arm for such a database and so would ask: 1. Has anybody done this already, and if so could you point me at it so I might use it when needed ? 2. If nothing is currently available, would RCM and E consider building the database and appointing authors to create the data?

Hi everyone,   I would like to obtain the article and plans for the DB designed Fokker DVII which I believe was published in December 1978.   Is this possible, can anyone help?   Thanks in advance,   Bob.     @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);