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Member postings for John Roberts 9

Here is a list of all the postings John Roberts 9 has made in our forums. Click on a thread name to jump to the thread.

Thread: Wot 4 Foam E Mk2 - CoG
07/03/2020 11:44:00

@Wilco Wingco

Mine is set at 80mm and has now had hundreds of flights without incident so I would say it makes a safe & reliable starting point.

The model does seems very tolerant of a wide range of CoG points and I have flown mine with it set as far back as 90mm (experimenting with prop hanging!) and as far forward as 70 mm (using an oversize battery) and, frankly, it didn't make a whole heap of difference.

My advice is go for 80 or just a tad less and all should be well.

I hope your grandson enjoys it because for such and cheerful foamy it is great fun and super value for money.

Thread: Recommend a Hotliner Please
19/12/2019 11:13:00

Hello and thank you for the replies.

One of the reasons I decided to ask here for suggestions was because my own online searches for hotliners seemed to produce very little of interest. This seems to rather bear out the general feeling expressed above that hotliners are currently out of fashion.

One of my clubmates has a Staufenbiel Hawk 3 which is a bit of a missile and, whilst that appealed, it no longer seems to be available. That said Horizon Hobby are still listing a 'Staufenbiel Cheetah R 1750mm' which looks similar and could possibly fit the bill. Anyone had experience of this model? It struck me that the RR version using 3s batteries would probably just be reasonably quick rather than genuinely fast. Perhaps the ARF version with a different motor and 4s batteries would be a better way to go?

My "sprightly warmliners" are a 2 metre Multiplex Funray (circa 750 watts and weighing just under 2Kg) and an AeroNaut Pepper, as built by David Ashby and featured in the April 2019 edition of RCM&E, (1.2M, 0.8Kg and around 450 watts). Both, especially the Pepper, are reasonably quick but, for some inexplicable reason, I would like to push the boundaries further. My wife thinks (probably correctly) that I am regressing into a second adolescence!

Many thanks once again for the responses so farsmiley.

18/12/2019 16:17:11

I already have a few electric gliders that range from sedate through to reasonably sprightly warmliner but I am beginning to feel the need for a genuine hotliner and would welcome suggestions & recommendations please.

My requirements are for something up to about 2M wingspan, suitable for flat field flying and up to about 5-600 quid including motor, esc & servos but these, for the most part, are pretty loose criteria and I am happy to consider things outside these boundaries.

I know others have asked similar questions in the past but the most recent thread was about 5 years back and so likely to be out of date now.

Thanks in advance.

Thread: Keil Kraft Caprice CoG
15/07/2019 15:48:35

Due to the very narrow fuselage I have opted to use a Deluxe Materials product called 'Liquid Gravity'. This makes it easy to drill a small access hole into the top of each compartment and slowly add enough weight until I get perfect balance. Add a few drops of cyano, plug the hole(s) and top it off with a small patch of tissue. Job done!

In truth, simple lead shot would probably work just as well and be cheaper too but Liquid Gravity offers a very convenient solution.

14/07/2019 08:36:52

Thanks everyone for the interesting replies. Although I have flown R/C powered models for quite a few years this is my first real foray into free flight.

Although I expected to have to add a bit of lead to the nose (perhaps 5g), what surprises me is just how much is going to be needed. 75g will increase the weight of the Caprice by 60%!

My plan now is to open up the 2 forwardmost compartments in the nose and add the necessary weight. These compartments are pretty slim so I was thinking of pouring in a 'slurry' mix of lead shot and epoxy...….or is there a better way to do it?

Thanks once again.



Edited By John Roberts 9 on 14/07/2019 08:46:12

13/07/2019 18:50:21

The wing chord is 16cm and the recommended balance point is 9cm behind the leading edge. That seemed a long way back but I assumed it was required due to the lifting tailplane.

The plan does make reference to the 2 compartments in the nose being used to accommodate balance weights so perhaps adding 75g is the expected norm. It looks as though I am going to have to do some surgery!

13/07/2019 18:32:20


I have just completed a KK Caprice for my next door neighbour and my final task was to check the CoG. Putting it on the balance showed it to be surprisingly tail heavy and it will require 75-80 grams of noseweight to get it balance as per the plan.

The model only weighs 125g and so another 75g seems like a (relatively) huge amount to have to add.

The model is built exactly as per the instructions, using the supplied materials in the kit and is covered in tissue & dope.

Has anyone else had a similar experience with this model?

Thread: Commons Science and Technology Committee Enquiry on Drones
09/07/2019 19:04:08

Irrespective of what the EU regulations might say the Baroness was absolutely unambiguous when she said that all unmanned flying objects above 250 grams will be required to have a transponder fitted within the next 3 years. Their plan is to have some kind of super all-seeing air traffic control system that will be able to identify every aircraft, manned & unmanned. The only exception mentioned was the sub 250 grams class although she also left the door open for even that modest cut-off figure to be reduced should further research indicate that tiny drones represent a risk.

Edited By John Roberts 9 on 09/07/2019 19:05:25

09/07/2019 12:46:05

I watched the whole thing this morning and was pleased to note that the Committee were, for the most part, surprisingly sympathetic towards recreational model flyers.

Dave Phipps made some good points but I am inclined to think that to the average, poorly-informed, non-flying viewer, David Dunn will have come across as being more compelling because of the frightening picture he painted of swarms of hacked drones making attacks etc. I fear that most people will simply accept his speculations as 'fact'. His solution is to regulate/register/control everything and yet none of his 'solutions' would have any impact whatsoever on the malicious/criminal drone users who would simply sidestep all the requirements.

It was also irritating to hear him effectively liken drones to guns in the USA which simply feeds the media hysteria. I really hoped that someone would have challenged him for some stats about the number of injuries & deaths caused by firearms compared to those caused by drones.

The second session with Baroness Vere makes it abundantly clear to me that registration, testing and the fee are all now utterly unavoidable. Personally I found her at times to be smug & condescending in her delivery (warm words but withering tone when it came to model flyers) and there were a surprising number of topics of which she was 'unaware' or 'unable to respond' or vague. But none of that matters because the wheels are in motion and come November we will all be faced with a three way choice...…….give up, register or fly illegally.

Thread: Making an electric glider's propeller fold more positively
05/06/2019 12:20:29

I should add that having done this the brake engaged very positively indeed as soon as I closed the throttle was immediately obvious that it was working properly.

As I recall, on at least one of the models, I found that the throttle trim didn't need to be completely backed off to nothing for this to work. With a bit of trial & error I found a trim setting that was somewhere between the default mid point and the minimum which was enough to get the brake function working as intended. Probably just down to a slight variation between the ESC's because the Tx (Spektrum DX8) was the same for all the models concerned.

05/06/2019 12:12:44

Yes, I just clicked the trim button downwards until there were no more clicks left. Simple as that.

05/06/2019 11:44:08

I have found that on some ESC's the brake function doesn't work unless you have the throttle trim on the Tx reduced to almost nothing.

I suspect that with the throttle trim 'centred' (which is the normal default setting) the ESC will assume that the throttle is still slightly open (even though the motor isn't actually turning) and, therefore, will not engage the brake function.

YEP speed controllers seem more likely to exhibit this issue but I am pretty sure the same principle will apply to other makes. This fix has cured an apparently non-operative brake on three of my models (two gliders and one flying wing).

Certainly worth a try...……...takes a few seconds and costs nothing!

Thread: Electrifying a WOT4 Pro ARTF
23/04/2019 13:02:18

Exactly the information I needed.

Thanks Simon smiley

23/04/2019 10:08:46

Very neat job Simon.

I have been thinking about getting a Wot 4 Pro myself and doing an electric conversion.

It would be very helpful if you could provide specific details of the motor, ESC and prop you used please.

Thank you.

Thread: Damaged foam aileron
16/11/2018 20:43:28

I agree with Martin & Percy, it will make virtually no difference.

I hope you don't mind if I also offer a few words of advice about the cross-weave tape you have used. It is very strong and makes a great repair but it is susceptible to attack by ultra violet light. This causes the adhesive to dry out (takes about 3 months usually) so check it regularly and replace as necessary.

Thread: RC Transmitters - Retail Pricing
16/11/2018 15:59:51

Stearman65. That is a pretty good deal given that the included Rx alone retails for over £70. That said, for reasons that certainly defy logic, my heart is set on a DX9. I don't need the extra channel but, as the owner of an earlier generation DX8, I feel the need to see an 'upgrade'. Silly I suppose but, for me anyway, it is analogous to buying a new car...………….I don't want a new one which is the same as the old one. As the saying goes 'there is no fool like an old fool' wink....….….… is probably just a phase that I am going through and will grow out of it eventually!

16/11/2018 14:57:46

I will admit to being deliberately coy about the Tx I had in mind largely because I didn't want to kick start another re-run of the old argument about Spektrum vs Futaba vs Frsky et al. It has been done to death and I reckon most people are a bit tired of reading it.

Anyway, I am looking to replace my first generation Spektrum DX8 with a Spektrum DX9 Black Edition. All the UK retailers I looked at are selling at 359 quid.

In times gone by Spektrum occasionally released 'special editions' that included extras such as a free Rx or an aluminium carry case and I was hoping that one of these offers might come along for Christmas but no signs of that right now. In fact it seems as though Spektrum (Horizon Hobby) has stopped these specials completely as part of their overall UK marketing strategy

15/11/2018 12:34:44

My suspicion has always been that the manufacturers/importers have the retailers in a headlock when it comes to pricing. I doubt the retailer is making much at all on the deal.

As Peter Christy says above, the pricing of much of this equipment outside the UK tells its own story about markup.

15/11/2018 12:13:00

The retail prices being offered are 40 quid cheaper than manufacturers RRP. Whilst my current Tx continues to work very well, the set I have in mind offers more functionality (I am particularly thinking of flight modes for gliders) plus some useful frills like voice prompts etc. Also who doesn't like a brand new bit of kit occasionally!

It easy to understand why so many people are turning towards the (apparently) high spec offerings from Frsky etc. at remarkably good prices compared to the traditional mainstream marques.

15/11/2018 10:50:38

The festive season is just around the corner and my good lady has offered to buy me an upgraded Tx for my Christmas present. My existing Tx (from one of the 'big name' producers) has served me well for 7 years and so it made sense to stick to the same brand (familiarity and the fact that I don't really want to have to replace about 20 Rx's).

Two things immediately struck me. First, there only appear to be only a very small number of UK retailers stocking this brand. Second, and more significantly, all the stockists are listing my preferred Tx at the same price. In the UK retail price maintenance (RPM) is generally unlawful so is it just pure coincidence that all the UK retailers are selling at the same price?

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