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Member postings for Peter Christy

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

Thread: Moon landing
20/07/2019 12:21:49

I'd just left college, and had a couple of months to spare before starting my first full-time job. As a stop-gap, I was working for the local electrical goods shop (remember them?) as a salesman and delivery van driver.

The morning after the landing, we had all the TV sets in the shop window showing the dim, flickering images of Armstrong and Aldrin on the moon (all in glorious 405-line! Remember that?)

The crowd on the pavement outside got quite large, and was in danger of spilling on to the main road....!



Thread: Model vs Trees
19/07/2019 18:40:08

Rob: I'm not sure the engine reliability has changed that much in the last 50 years! The engines seem to be exactly the same as they were back then!

Our Colts had Lycomings up front. A bit agricultural, but they kept going! The Cessna had a RR Continental - much smoother but prone to unexplained stoppages, nearly always on the approach!

I'm sure it was just that one aircraft that had the issue! If it had been a common fault, someone would have known how ti fix it! As it was, I moved away from the area before they got to the bottom of it - if they ever did!

I still have fond memories of the Colts, though! Just like a full-sized Super 60......! laugh



19/07/2019 16:11:36

That probably explains the difference between what I was taught 50 years ago, and the air experience flight I had nearly two years ago!

Flying Piper Colts, I was taught to shut the throttle fully and do a glide approach, only opening the throttle if I was undershooting. The theory was, that if the engine stopped, you could probably still make the field. This was particularly important on the Cessna we used for spin training (yes, we had to do that back then, not just incipient spins!). The Cessna had a habit of stopping on the approach quite regularly, to the consternation of all concerned. Never did it to me, but I didn't fly it much! (Didn't like it much, either!)

My air experience ride was also in a Cessna, and I got quite worried when asked to land it using a shallow approach with about 1/3 throttle on. It felt very unnatural! It was also a bit disconcerting, because the approach to the runway was over a steep hill, rising to the end of the runway. If the donkey had quit, we would have had little option but to fly into the hillside!

I would have been much more comfortable starting higher, chopping the power and gliding all the way in! Given the turbulence coming off the hill, it would probably have been smoother, too!



19/07/2019 09:25:19
Posted by Peter Miller on 19/07/2019 08:42:41:

Something that is often forgotten and I have not seen mentioned here. The wind speed drops off as one gets lower, the boundary layer effect. Add to this the variations in wind speed.

It can also change direction quite markedly as well! Its not uncommon for the wind at 100ft or so to be in a noticeably different direction than it is at ground level - especially if there are large obstacles - like trees - around!

Trees and high hedges can also produce quite a lot of turbulence at low level. It certainly pays to keep the speed up a bit under such conditions!



18/07/2019 18:20:16
Posted by Martin Harris on 18/07/2019 12:48:41:

Pete - I suspect your full size experience contributes to your understanding?

Well, my full size experience is well out of date! I did go up for an hour long air experience flight at Dunkeswell in 2017, to celebrate the 50th anniversary of my first solo! I was doing quite well until we got on to steep turns, which is when I realised that my stomach isn't as strong as it was 50 years ago! wink

JD8: The oval descending turn - otherwise known as the "fighter break", favoured by Spitfire and Hurricane pilots during the war as they couldn't see the runway over the engines during a straight approach!

And yes, it can make judging the approach a little easier, as it can be stretched or shortened by adjusting the turn.



Thread: Ball joint tips?
18/07/2019 18:10:30

Ball joint pliers! (a Google search will provide plenty of options!)



Thread: Model vs Trees
18/07/2019 12:28:41

I was always taught to control speed with the elevator and height with the throttle. There may be exceptions during aerobatics, but it works very well in circuit flying!



Thread: Radio Link
18/07/2019 10:01:41
Posted by robert chamberlain on 18/07/2019 09:11:49:

Just wondering. With freq hopping ,just how many hops does it do in a second.---Bob

Quite a few, but that's not the whole story. A thing called the "Media Utilisation Factor" comes into play as well. For practical purposes, you can think of the MUF as being how long the transmitter is actually transmitting for in any given period. (Yes, I know power and other things come into it, but lets keep it simple!)

If the transmitter is NOT LBT compliant (Listen Before Transmit), you are limited to a MUF of 10% or less. In other words, you can only transmit for 10% of the available time. If you use LBT, this figure rises significantly, but is still nowhere near 100%. Compare this to 35 MHz FM, where the transmitter is transmitting continuously (ie: 100% of the time), and you will see that there is a big difference between the two systems.

If you look at a typical frequency hopping system on a spectrum analyzer, you can see the channels hopping faster than the eye can follow. The speed varies between manufacturers and whether they employ LBT or not (not all do).

So the short answer is - er, it depends! But it is quite fast, nonetheless!



Thread: Re: Looking Back 43 Years
18/07/2019 09:31:01

That's true of any form of competition, C8! I remember the early helicopter events where if you could take-off, fly a circuit and land in the same field, you stood a chance of winning! (My flying is still a bit like that! wink )

Nowadays, a contest machine with all the radio gear, batteries, chargers etc runs to a thousand or two!

No wonder competition flying is dying....



Thread: Electric Cars.
17/07/2019 17:01:50

Interesting piece on the lunch time news (BBC TV) about new car charging points and range concerns holding back customers.

The piece was showing a new "supercharger" system being installed at a number of places, and claimed to be capable of charging a car in 10 minutes!

Unfortunately, there are no cars currently available capable of accepting a charge that fast! The man from Audi said they hoped to have one next year - at a price!

The people installing the chargers were quite gung-ho about it, claiming they hoped to have "around 40" installed in the UK by the end of next year.

There are more than 40 pumps within a 30 minute drive from me in rural Devon!

These chaps have a long way to go.......




Edited By Peter Christy on 17/07/2019 17:02:27

Thread: Perry carbs.
16/07/2019 12:18:48
Posted by Trevor Crook on 16/07/2019 08:05:47:

Not sure what the tie-up between Veco and HB was. Someone else in my club had an HB25, which looked very similar to my Veco19, except it had mounting flanges on the backplate.

The Veco 19 and HB20 were internally identical. All the bits seemed seemed to be interchangeable. The Veco was an excellent little engine, the Rolls-Royce of small engines in its day. I had one for years, and it powered my first "Lark" helicopter! However, the HB25 was an enlarged version designed originally for the Graupner Bell 47 helicopter. Aside from being bored out (I don't know if they changed the stroke or not) the .25 heli engine was also ringed, and that was a truly superb motor. I still have one in a "Lark" today!

The Webra Blackhead .61, HB61 and Veco .61 also seemed to share a lot of parts in common, as did their .40 siblings, so there must have been a tie-up, at least for a while. Webra then went down the Schnuerle port route with the Austro-Webras (which appeared to be identical to the HPs), whilst HB went the Perry port route.

However, to get back on track, the Perry carb was notoriously susceptible to the tiniest speck of dirt in the fuel, and could also be fiddly to set up. Once you hit the "sweet spot", the would run beautifully, but this required patience and tiny adjustments to achieve.

Most of us gave up and fitted Kavan carbs! These were just as good as Perrys - arguably better - and certainly easier to set up! They were also a little less fussy about fuel cleanliness! No "O" rings to perish, and being all metal, they didn't suffer from the plastic degradation that affected many Perry carbs.

I think Kavan carbs are still available, though not easy to find. All my HBs are now fitted with them!



Thread: Commons Science and Technology Committee Enquiry on Drones
13/07/2019 19:36:50

Thanks, Martin!

13/07/2019 18:47:39
Posted by Steve J on 13/07/2019 18:04:36:

I'm hoping that she won't survive the ministerial reshuffle that is coming at the end of the month and we have a more sympathetic aviation minister in August.

You and me both! And probably a lot of others, too!

But please keep us updated on this. You obviously are more across it than me, and we need all the firepower we can muster to try and get a reasonable outcome.

If she has mislead a committee, she could be in serious trouble!



13/07/2019 17:19:54
Posted by Steve J on 12/07/2019 10:27:50:

I finally forced myself to listen to Ms. Vere's evidence.

Contrary to what she said, the EU delegated regulation does not require all UA over 250g to have electronic identification and geofencing. Only UA with automatic flight modes are required to have direct remote identification and geo-awareness.

I got the impression that the meeting with the associations didn't go very well...


Steve: Have you got chapter and verse on this? ie: at what time in the feed she said it, and also a link to the document with a reference location?

I ask, because my understanding of proceedings like this (and I am not a lawyer!) is that misleading a parliamentary committee is as serious as misleading parliament and demands at least an apology and correction or a resignation!

We need to feed this info to David Phipps so that he can follow it up. If I can get the precise timings and locations, I tempted to write to the committee chairman myself to complain about it!



12/07/2019 23:17:47

Good point, John, and that card has been played in the past.

Protocol dictates that at a meeting with government officials, they must provide someone of equivalent "rank" to your representative.

I think it was possibly during the CB crisis that the BMFA dragged our President (?) - a then very senior former RAF man - along to a meeting, and the Home Office had to provide a civil servant of equal stature.

Not sure how much it achieved at the time, but we did eventually get what we wanted - 35 MHz!



Thread: Flying car
12/07/2019 23:13:07

The driver needs to buy a lottery ticket - NOW!




Thread: Skyleader Clubman Super 35Mhz TX battery wiring
11/07/2019 13:54:42

Chris: Sorry, I've come a bit late to this thread! If you look here (and scroll down a bit):


You will find the complete circuit diagrams for a Skyleader Courier set, including the (in)famous split circuit charging. It even has the colour code for the wires on it!

I appreciate that your set isn't a Courier, but the battery wiring should be the same - probably the RF boards, as well!

I wouldn't be too worried about the age of the equipment. There is no reason why it shouldn't work as well today as when it was first made. As long as there is no sign of black wire corrosion, just fire it up and try it.

Do a careful range check, and also check all the pots. This is best done by moving each control SLOWLY from one end to the other. Banging the sticks hard over won't show up any potential rough spots on either the transmitter or servo pots.

If you don't find any problems, you are good to go!

I still have a couple of 27 MHz AM sets from the mid 60's and early 70's in perfect working condition. I keep getting tempted to put them in a model again, as CB seems to have died the death unless you are close to a motorway!



Thread: Eddy Currents
11/07/2019 11:32:47

Simon: That's partly what those huge capacitors are for in an ESC - to smooth out the current draw. It also explains the big flash you get on some ESC's when connecting them, as the smoothing capacitors charge up *very* rapidly!



11/07/2019 10:15:42

Eddy currents are induced in conductors placed in a changing magnetic field. The currents in the battery leads are essentially DC - they do no change, well, not quickly, anyway. Therefore the chances of eddy currents forming in the battery leads is about - er - zero!

Where they *might* occur is in the three motor leads, where the current is being switched quite rapidly. However, given the short length of these leads, plus the facts that they are pretty close together and have low impedances at each end, I don't think any benefits will ensue from taping the leads together.

Could look tidier, though!

A similar situation occurs when people buy very expensive speaker leads for their HiFis. There is no measurable improvement over cheap 13 amp mains leads!



Thread: Commons Science and Technology Committee Enquiry on Drones
11/07/2019 10:05:01

Also interesting that other speakers in the debate seemed to be equally well clued up. Indeed the only one who failed to grasp the situation, or answer any of the questions put to him, was the government minister! PWC, whose advice he seemed to rely on, have been shown repeatedly to be incompetent, and indeed at one time were banned from taking on any more government work, IIRC.

The only consolation I draw from all this is that successive governments - of all flavours - have proven repeatedly incompetent in pretty much every area they touch. Political expediency nearly always trumps common sense.




Edited By Peter Christy on 11/07/2019 10:05:53

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