ptwizz

Simon, You can be assured that whatever this engine ends up in, it will be shown off to anyone who has expressed the slightest passing interest. End of year progress report: I have now made the supercharger drive gear arrangement and its housing. The supercharger is driven through a planetary gear when 'engaged' and driven at low speed through a roller clutch when not engaged. The planetary gear has a floating ring gear, so that when a brake band is tightened the ring gear is stopped and the blower is driven at 4 X crankshaft speed. I have a few fiddly bits to do for the brake band actuation, then on to the supercharger impeller. The impeller looks exactly like a turbo impeller, but it's 5" diameter! Rather than try to machine it from a single billet, I will be fabricating it from a machined 'cone' and separate vanes. Each vane will have tabs which pass through slots in the cone, to be peened over and finally brazed in place. The impeller will run at 14,000 rpm max. At work, I have access to a 7.5kw pump test rig which I can use to spin it up and check for vibration, distortion and pressure / flow rates. Still have no facility to post photos. I only have the 'Insert other media' button available.

The word 'bathroom' may be a misleading description of a hole in the cockpit floor. Any jokes based on the word 'cockpit' in this context will be treated with appropriate contempt.

As a counterpoint: After 5 years with a paramotor, I have moved to a 3 axis microlight. It is absolutely true that paramotoring is cheap, safe and convenient. As a way into aviation, it was exactly the right thing for me when I started. Among the reasons for moving to a microlight is the capacity to take a passenger. Of course, it is possible to take a passenger on a tandem paramotor or trike, with the appropriate licensing, kit etc., but It is a lot easier to find friends who are willing to climb into a seat and shut the door than friends who are willing to strap themselves to me and run. I must take issue with some of what has been said (or implied) about safety. Microlights do not fall out of the sky due to mechanical failure any more than paramotors. Pilots are taught to fly so that they can glide to a safe landing area at all times. Forced landing is part of the syllabus and test. Where incidents have been attributed to mechanical failure (read engine failure) it could be argued that the pilot should have every opportunity to land safely and failure to do so is due to pilot error, either before or after power loss. Part of the definition of a microlight is the maximum stall speed of 35 knots. This is also the speed at which the aircraft lands, so a forced landing in a poorly chosen ploughed field or marshy area may not be the most comfortable experience, but is slow enough that the protection of the cockpit frame prevents significant injuries in majority of cases. I am personally satisfied that a microlight is just as safe as a paramotor. The overwhelming majority of accidents with both types are ultimately down to the pilot, either through poor flying or poor maintenance. Whichever you choose, do so because it's what you want and have fun.

I still don't have the facility to post pictures. If anyone is still following the slow progress of this project, there is a complete photo record of the build here https://groups.yahoo.com/neo/groups/R_and_R_engines/photos/albums/1849802645 Much time has recently been devoted to getting my microlight up to date with servicing etc, installing a new bathroom and a string of issues with my wife's bike. Winter should see more progress, provided I don't dragged too far into redecorating.

So who enforces the laws that (quite rightly) prohibit flying close to buildings etc?

A little more progress.. The engine now has all it's rockers and pushrods assembled, so I can turn the crankshaft and all the valves open and close at the appropriate times. That's the valve timing phase of the project complete. I've just ordered some more large lumps of metal, most of which will end up in the bucket under my lathe. The first will be the 'seal plate' which closes the oil space at the front of the engine and houses the supercharger drive gears. The second will be the supercharger planet gear carrier, which also functions as the nut which pulls up against all the bearings and spacers on the timing end of the crankshaft. I still can't post photos here. Kiwi - I see Geoff about once a week. I believe he also designed, or had a hand in, the BRM H-16.

I now have a complete set of rockers, each fitted with bronze bushes and a roller tip running on a hardened pin. The cylinder heads require more modification to provide clearance to the new rockers. I had measured one head, made all the rockers and then found that the heads are all slightly different and the one I had measured was the only one which the rockers would fit. As a result, I've had to make another substantial fixture to support each head on it's side so I can machine them all to match. Unfortunately, I still can't post pictures, despite clearing all cookies, history etc.

It's the first coming - of the spaghetti monster. https://en.wikipedia.org/wiki/Flying_Spaghetti_Monster

The fundamental issue which everyone has obliquely referred to, but not explicitly stated, is the relatively low airspeed of PG/PPG/Paratrike aircraft. The triangle of velocities calculation is correct for the given input parameters. Flying a fixed wing aircraft at 70kts in winds of 10-15kts, a pilot should check location every few minutes. If the predicted track does not achieve the desired heading, then a correction must be made. This might involve a radio call for a local weather report, followed by recalculation with the new parameters. If you are flying PPG at 25kts in winds of 10-15kts, the potential for heading errors due to changes in the wind is greater, so there will be more requirement for updating calculations. The GPS is able to update the calculations quickly. You could do the same using your slide rule (or calculator for the young 'uns), but it would take up much of your attention. Incidentally, ideally you wouldn't fly to a compass reading directly. If you use the compass once to identify a landmark on the correct heading, you can then keep aiming for that landmark. This effectively corrects for wind drift, although it does not result in the most efficient flight path. P.S. A landmark is a fixed object on the ground, not a boat at sea, or (as I once overheard) 'that cloud that looks like a cat'.

Inverted flight has to be carried out quickly, before physics notices what you're up to. See also Wile E. Coyote.

Mine caught fire - did i do something wrong?

Trying to keep this reasonably succinct... As we are all aware, a cat will always land on its feet and buttered toast will always land butter side down on the workshop floor, carpet or cat. So, if one were to attach a slice of well buttered toast, butter side up, to the back of a cat (using a suitably comfortable harness), the universe does not know whether to allow the cat to land on its feet or the toast to land butter side down. Hence, the cat/toast combo hovers a few inches above the ground. I have a photo to support this, but I still can't post images! Using the same principle, we are also aware that a small, expensive engine component, if dropped, will find its way into the tray of used oil, sludge, fag ends etc. This happens even if the tray is on the other side of the workshop, showing that the universe is prepared to reverse entropy just to be awkward. We also know that everything happens more when it is hotter. On a summer morning, just as one is assembling ones paramotor, one drops a small but vital part. As one struggles to find it, the sun warms the day and the part becomes harder to find, until one is a sweating, grounded and agitated wreck. So, we construct an engine with a bath of used oil and sludge at the bottom (sump) and an expensive part at the top (piston). The expensive piston is drawn towards the sump, but this won't turn the motor. Heating the arrangement increases its entropy and allows the universe more energy with which to draw the expensive piston into the oily sump. An arrangement which can burn a convenient liquid fuel to produce cycles of heat and cold causes the force drawing the piston to the sump to rise and fall, turning the engine. Viola!

In a similar vein: How an internal combustion engine works: Air is invited into the carburetor, with the promise of free drinks. Air mixes with the drink (fuel) and becomes confused. Confused air is ushered into the cylinder, before it really knows what's happening. Once inside, the doors are closed. Then the wall (piston) starts closing in (as experienced by humans with cider). A lot of confused air is packed into a small space and it only needs a small spark to initiate panic. Air goes absolutely mad and starts kicking out in all directions, pushing the wall (piston) back until finally the doors are opened and the air charges out with a lot of noise. I have another explanation involving entropy, but it goes on a bit and involves cats and buttered toast.

Returning to the original question: Is the clutch a positive safety feature? Benefits: If your engine is idling and you put your hand, lines, genitals etc. into the cage, you won't get hurt, poorer or embarrassed in front of your mates. Possibly easier starting. Costs: More weight, another possible source of failure, possible small increase in drag with engine off, prop continues to spin when engine shut down.

Unfortunately I've lost the facility to post pictures on this site. I've posted the issue under the 'tech' section and awaiting a response.

I appear to have emigrated to Canada in the process of logging out and in again.

A new beginning: My paramotoring kit is now sold and I am in the process of purchasing G-BZNP, a Thruster microlight. A new paramotorist will shortly begin training in Cornwall. I have directed him to PMC so look out for a new training Blog. A combination of weather and other commitments prevented me from flying the paramotor as much as I'd have liked. The microlight offers an extended weather window and will be stationed 10 minutes from my home. It also gives me the opportunity to carry passengers. Paramotoring has been fun and allowed me to fly independently at very reasonable cost. I would recommend it to anyone. I will continue to lurk here and update the radial engine build thread so long as anyone is interested.

I have the same issue. This: is not visible. I am on the same PC, same browser (Chrome) that I have been using for some time without issue. Hence no update to the radial engine build with picture of 5 axis manual milling!

Nice use of wood to fix a bent Ti frame. Kind of raises the question: Why not make the frame from wood?

The OP stated his weight at 88kg NAKED. I would expect him to be well over 90kg with clothing, boots, gloves, helmet, etc. N.B. Dell S is not a popular data source. It took me several attempts to moderate my comment to 'not a popular data source'.

This is why I have a van and my wife has.... another van! (Technically hers is an MPV, but the rear seats have rarely been fitted).

How did you both get in the car with the paramotor in the front seat?