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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: RPM Conundrum
10/06/2019 08:53:23

I had an IC twin once that ran 10x6 APC props, I tested 7 props one after the other on one engine and found something like a +/-200 rpm difference at 10,600 rpm, so even props can have a little variability.

Thread: Electric Motor 'clunk' When Opening Throttle
05/06/2019 17:30:59

I had this on a Hyperion motor and changing ESC settings did not help and neither did it have any end float. I finally stripped the motor down and the stator coil could rotate a little on the mounting shaft. There was a small piece of about 1mm rod that fitted into a groove on the outside of the shaft and the inside of the stator to stop the stator from rotating. This rod was too small, so I removed and fitted a slightly larger bit of piano wire and the motor now starts up with much less clunking or hesitation.

Thread: CAA registration consulation
17/05/2019 09:33:51
Posted by PeterF on 17/05/2019 09:07:10:

The 170,000 figure, right or wrong is their estimate for the number of registrations in the first 18 months.....

Edited By PeterF on 17/05/2019 09:12:02

This is what I have replied about these numbers in consultation and letters. As has been stated elsewhere, in terms of what we spend as modellers it is a small number, so I will pay, I have made my displeasure known but I will not be taking an enforced break, flying without registering etc.

I have a serious concern of the method used to arrive at the 170,000 registrations over the initial period. This was calculated as a per capita average of registration take up in the USA and Ireland, two countries that are culturally different to each other. Ireland being closer to the UK should have been used as the basis giving 128,000 registrations. This would increase the £16.50 charge closer to £22.00. The charge ($5 for 3 years) on an annual basis in the USA is just over £1/annum and in Ireland (5 for2 years) it is just over £2/annum. The fact that the CAA is proposing a charge 10 to 20 times higher than the countries that Tthey based your statistics on means that the charge will actually be a disincentive to registering and will act to reduce the per capita registration in the UK. This means that the purpose of the scheme to ensure education of drone users is not met.

17/05/2019 09:21:03
Posted by cymaz on 16/05/2019 22:26:41:

It seems the CAA know the difference between a multi rotor “ drone” and a model aircraft / helicopter


The CAA could tell many months ago before the recent updates on that page when they gave model aeroplanes and helicopters below 7kg the >400ft exemption but not "drones".

17/05/2019 09:07:10
Posted by Peter Christy on 17/05/2019 08:35:34:

Exactly right, C8! I shall be taking a break this winter and will see what happens when the "170,000" figure fails to materialise.


The 170,000 figure, right or wrong is their estimate for the number of registrations in the first 18 months stated clearly in the consultation document, not the initial sign up, so a Winter break may be pointless in trying to show them that the number is wrong.

Edited By PeterF on 17/05/2019 09:12:02

27/04/2019 14:22:01

The operator registration and pilot testing are going to happen regardless of the cost and the vast majority of us are both operator and pilot. I am the secretary of my club and the thought has just struck me, what tack should a club take vis a vis the registration and test status of its members. Do we need to take the active role of ensuring that our members have current registration and test passes to their names, I do not know that answer at the moment, I have just started sound checking, I really do not want to be policing more stuff. What is BMFA's stance going to be on this and will their insurance cover you if you are operating illegally by not being registered and having passed the test.

Thread: LiPo Internal Resistance
26/03/2019 21:23:47
Posted by Chili Pants on 26/03/2019 21:13:33:

To get IR or C rate I used this on line tool, quite simple to use, just input your battery details, dont know how accurate it is as I am new to all this electric stuff but it saves me from making my head hurt.

Here`s the link

That is the same calculation method as the one I referenced above on RCGroups and gave the equation for, just coded up by someone else, although they have extended it to calculate the voltage drop that occurs at maximum current.

26/03/2019 14:39:53


I knew it was somehow related to heat generation, taking the equation apart explains it well. The constant 6 will effectively be the combination of battery mass per mAh, specific heat capacity and an allowable temperature rise. There are a range of battery weights for a given mAh rating, so a better equation would be based on that, but the one shown seems to be sufficient.

26/03/2019 13:43:45


I believe that your arbitary 30% increase in IR is very conservative and will result in you dumping batteries prematurely. Use the calcualtor or the equation and see how things pan out for a 30% increase in IR. Because the formula is square rooted, this make a 30% increase in IR about a 15% reduction in C rating. I believe that you can normally absorb a much larger reduction in C rating before seeing issues.

26/03/2019 13:39:13

The equation was published at some point if you want to make up your own spreadsheet to calculate things backwards rather than working the on line calculator iteratively.

Max current = square root(6 * Capacity / IR )

Effective C rating = 1000 * Max current / Capacity

Max current is in Amps

Capacity is in mAh

IR is in mOhms and is the IR of the cell with the highest IR in the pack.

The milli in the battery capacity and the IR cancel each other out.

I believe that if you have good batteries that over time you could let the IR double if they are still working. I have some 2200mAh batteries, new 7mOhm, aged 12mOhm, the calcs above suggest that the C rating has fallen from 20 to 15 and they still work OK in planes that draw 25Amps, although they are warmer at the end of the flight and flight duration is down compared to the new ones. However, my 3700mAh batteries that are my mainstay now have IRs of around 14mOhm (no record of as new) giving effective C of 11 and in one plane that draws about 55 to 60A they are now very sluggish.

Edited By PeterF on 26/03/2019 13:40:38

26/03/2019 13:13:41

Have a look at the following RCGroups thread on this subject and the calculator for determining max continuous current from cell capacity and IR. **LINK**

Thread: RCV Engines
22/03/2019 09:16:51

Here are a couple of photos of the installation of an RCV60SP in my mosquito, I put scoops into the cowls from the air inlet below the spinner curved through 90degree to the the air flowing vertically over the fins. All air entering the inlet flowed into the scoop and the scoop was quite tight to the fins so all air flowed through them and not around them. The air exits were furtehr back in the crankcase area. I had no issues with engine overheating with this set up.

I have same comment as Don regarding lengthy running in, although in my case I kept a high tickover speed to avoid dead sticks as the Mossie landed quite fast this was not an issue.

1418 cooling baffle installed (custom).jpg

1480 cooling (custom).jpg

Thread: RCM&E Fly-In 2019 - general chatter
21/03/2019 19:04:18

Thanks Pete,

I'll see what David says as the linked page says "the hangar which we’ll equip with a small bar and use for evening gatherings and casual indoor flying", so it may not be available for storage.


21/03/2019 16:48:39

If I bring down a large biplane for the weekend will there be anywhere to leave rigged models overnight on the Saturday, or will these need to go back in the car overnight. I had also heard Barkston was installing power for charging for flight batteries, any idea if this is true.

Thread: Flair Tiger Moth, help needed.
28/02/2019 11:19:56

You could try registering with RCScaleBuilder ( site as there have been quite a few Flair Tiger Moth threads on there and contacting the people who have built them.

The CoG should be located at the rear of the fuel tank, I have seen that mentioned in the Flair TM threads and that is where the Falcon Models 1/4 scale TM that I have balances. Can't help with Flair TM plans I am afraid.


Thread: Propguy?
27/02/2019 21:28:44

Both times I have ordered from them the item was out of stock. I asked for a refund on one but that never materialised, however the prop did after 5 months. I will check the stock with them before ordering in the future.

Thread: Winters Here Who's Been Flying ?
27/02/2019 21:24:54

Well, that was the week that was ............. unexpected to say the least for late February. Last year we had a winter holiday and there was snow on the ground when we flew out of Newcastle. We have cut the grass at our field and the ground is firm when it is normally too wet to cut yet and quite soft underfoot.

I have been flying on four afternoons out of the last seven, and of the other three I was doing other outdoor things on two of them and could have flown. Yesterday was the best day, 17degC and no wind, ideal conditions for my quarter scale Tiger Moth. I was not expecting to fly it until much later in the year but had a great afternoon. The air was so smooth that I flew it inverted for the first time since I maidened it nine months ago.

Thread: Forum members' new models: Let's see them.
25/02/2019 21:41:25

Hangar 9 CAP 232, around 80" wingspan, running on electric, 8S 5000mAh, 2.5kW at WOT with freshly charged batteries, hauls the 16½ lb weight around with authority. Whilst the plane can be set up for 3D, the power is not enough for that so I have the throws set up for smooth aerobatic flying. This is not a new plane but it is new to me, this is the first time I have bought something second hand because I was not sure I would like this sort of plane. Gave it a good overhaul and checked everything out thoroughly before flying. I had been looking for a larger aerobat and this was set up to match batteries already in my possession. Maiden flight yesterday and it flies really well, rolling and looping on the first flight, I felt really comfortable with it straight away. Needless to say that it is a keeper.

cap 232.jpg

Thread: How many charges will I get from a 12 volt Lesiure Battery ?
24/02/2019 10:03:50

I was faced with this conundrum some while ago flying an EDF model that has 2 x 8S 5000mAh packs, these are rather expensive to buy multiple sets. I also fly other larger electric models as well, but this is the highest capacity. Each recharge would take about 24Ah from a 12V battery, and a 100Ah leisure battery as someone has said should not be discharged below about 50%, I would get 2 charges. I was also not keen to go down the generator route, a small noisy open frame gennie would annoy the rest of the club members in the pits and a quiet suitcase Honda type would be expensive. Therefore, I have bought 6 low C rating 6S lipos of 16,000mAh capacity (16Ah) and put them into a parallel bank of 96Ah but nominally at 24V and it weighs less than a single lead acid leisure battery and give me 3 times the usable capacity. Admittedly, it cost 3 times as much as a single leisure battery, but Ah for Ah it cost no more and is a lot more convenient. Luckily my charger can be fed with up to 50V DC input so the supply voltage is not an issue.

I recognise that this is more of a specialist need, not suitable for everybody, but thought it worth mentioning as another way of solving the problem.

Thread: Digital incidence meter
23/02/2019 16:57:42

£10 royalty payment for use of trade marked patent pending designlaugh although I note your bar is gold not red. Hope it works out for you.

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