February 2019

In this month’s issue:

  • Down on the Farm with Tony Palmer
  • Paul Cave’s Funeral
  • CAA Recommended to Promote GPS Use
  • Denied Access to Controlled Airspace – Report it!

Down on the farm 11, January 2019

Klemm L25C G-ACXE

I started making the guides to my drawing but had to grind up a form tool to make the intricate shape to act as the valve spring nests. We dug out the new valve springs only to find them rusty, unfortunately the valve springs are one of the hardest working parts in an engine and due to the many millions of stress cycles they will see in their lifetime I think a rust pit is not ideal! (approx. 9.6 million in 100 hours).  We are looking for a new set and I am actively making data sheets for the new springs. The old ones may be just about OK but they will need careful inspection, but new ones to the correct dimensions and loads etc. will be better.  It will pay us to get more Pobjoy owners interested to get the numbers up and the prices down.  The new ones were also under length and the wrong diameter so I have stopped the guides temporally.  The new and existing valve springs have been subjected to much analysis in that we needed to know the force at the point of valve opening, the spring rate etc. None of this was available in the manual so we had to come up with tools and methods to achieve these goals; see picture where we are measuring the force with regard to valve travel which we are monitoring with a dial test indicator.

A Pobjoy finned cylinder in a test rig with a digital load measuring tool and a dial test indicator.

Pobjoy cylinder using a digital load measuring tool and a DTI (dial test
indicator) to test the valve spring loads and travel

The crank components are now built and in the crankcases but not bolted up yet as we had a problem with the new gear that drives the cam drum. This shaft had been manufactured locally about 8 years ago, the ground shaft had been found to be not parallel but that was cured with a drill and emery cloth, the key way was not to the correct size but again the key was adjusted to suit. The real problem was that the gear teeth had been cut to the wrong dimensions and when assembled it ran very rough.  The manufacturers say it will be expensive to find out the actual pressure angle of the old gear and they don’t have a cutter anyway as it will be a non-standard.

General Flying

Since the river flooded last year it has been very dry and the strip has dried out very nicely with many good flying days. Tony Berryman has been instructing in the Tiger since the flooding and on the 2nd January I did my first Tiger Moth Solo (and tail dragger) and I have flown the Bristell a fair number of times. I hear through the grapevine that even with the recent dry weather Goodwood is still not operational.  I have just come in from taking the land rover discovery with the roller attached up and down the taxi ways and the airstrip to get rid of the worm casts and to flatten it hopefully ready for the new season.

GASCO safety evening at the Swiss Cottage on 6th March 2019.  Tell everyone who would benefit !!

Tony Palmer

Paul Cave’s Funeral

I and a fair number of the strut attended Paul’s funeral yesterday. We went back to the Shoreham airport building afterwards to talk about Paul and give our condolences to his family and friends. The funeral was attended very well almost filling the chapel.

[It’s still possible to make a donation to Paul’s chosen charity: Aerobility. Ed.]

Tony Palmer

CAA Recommended to Promote GPS Use

Last week, I accompanied a friend on a night VFR flight from Gloucester to Shoreham.  My poor colour vision limits me to day VFR, so this was an opportunity to experience something different.  Tracking the Midhurst VOR, we requested MATZ clearance from Odiham and got it, with a “remain clear of the ATZ”.  There is a 2 NM gap between the Odiham and Farnbrough ATZs, and at that point, 15 NM from the VOR, the accuracy is starting to diminish.  No problem, we had moving map GPS and using that  threaded happily between them.  However, at the time I commented to my friend that without the GPS, that wouldn’t really have been possible with any confidence.  Well, not for me at least; no doubt cunning use of a within range DME could have given added accuracy.

Screen capture from a SkyDemon track log showing a track through the Odiham MATZ.
I remembered this incident when I received notification that the CAA have just published their ‘Causal Factor Analysis of Airspace Infringements in the United Kingdom
1 January – 31 December 2017′ (downloads as a PDF).  A major recommendation amongst the mitigations identified concerns moving map GPS.

Without doubt the most help to avoid infringements comes from a GPS enabled moving map with airspace warning systems and pilot alerts. In some of the cases reviewed, the pilot had such a device but didn’t use it to its full capability. Had they done so, their infringement would probably not have occurred. It is the WG’s view that if the CAA and the ANSPs are serious about reducing infringements, they should be setting policy which results in greater use of these devices and training in their use.
This could include
1. Basic training, which in many schools still emphasises Dead Reckoning over GPS.
2. Making it be known that the use of GPS will, in line with a be noted and, where appropriate, considered in post- infringement action
3. Financial assistance in procuring such a system.
4. Ongoing or refresher training of current pilots

Point 3 is interesting, but perhaps we’d better not hold our breath!

Richard Griffiths

Denied Access to Controlled Airspace – Report it!

The All Party Parliamentary Group on General Aviation are encouraging pilots to let the CAA know if you have been denied access to controlled airspace.  There’s a form for the report: FCS1521.


Regular meetings are in the Lounge Bar, The Swiss Cottage, Shoreham, 7:30pm.

For the latest list of events, go to the Events page on the Strut website.

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