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AndyB

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Posts posted by AndyB

    Cloud dodging

    in General paramotor discussion

    Posted

    I just had to fly this evening as we don't often get easterly wind in Teesside...and reasonable wind at that. Measured 8 or 9 mph and gusting 12 mph.

    From my friendly farmer's field it is due east to the highest and best known peak in the area - Roseberry Topping. It is a fair old way, so I only wanted to go there with the wind in my face on the outward leg. It has also been raining all day, so I wanted to be able to about turn and run away from it. 

    It was well worth the trip, as I got to cloud dodge. Lots of bundles of low flying cloud that I had to either drop below or go around. In this video I get to Roseberry Topping at about 10 mins. I wanted to go round it at below the peaks height, so dropped off speedbar and pulled trims in for a slow potter. I knew it was going to be bumpy as I was flying over and between steep hills. It was!

    If you have sound on you will hear my heart skip a beat as I come round the peak and then power on to climb away (only 30 degree slope and forest below me!!!)......engine said no! Oh bugger. Lots of coaxing and I managed to get it run at up to 5800 rpm. Above that and it choked. I couldn't get enough power to maintain height with trims out and speedbar, but after experimenting I found with speedbar and trims in, I could hold level.

      

    Paramotor weight

    in General paramotor discussion

    Posted

    Maybe just worth pointing out that many machines currently rely on shear loads for the pivot arm pins. The Parajet V3 I have, has a pin that is retained by a slight push fit. The cage parts then prevent it working out if it came loose. The frame takes all the twisting loads of the arms, so in this case the pin ONLY takes shear load and no tension on it.

    Don't know bolt/pin size from memory, but a 10 mm bolt has 8.8 mm diameter (at base of threads). This size can take over 3 tonnes in shear. Two gives over 6 tonnes.

    I feel safe. :)

     

    Paramotor weight

    in General paramotor discussion

    Posted

    Vince, good to know about the bolts, but I'd like to understand the engineering :)

    Do the load dispersing discs have a spigot so one slots into the other, or are they just flat?

    If spigotted, then yes, shear load would be on the spigot and the bolt would just hold them together - so just just tension load on the bolt.

    If no spigot, then the discs prevent bending load on the bolt, instead converting that into tension on the bolt. However, the bolt would still take direct shear load of all forces perpendicular to the bolt (so mostly vertical). This load is total weight multiplied by maximum g force the pilot flies at. So for me never over 2 g, giving 240 kg.  But it is worth noting that the vertical load will only be a fraction of what the bolts are capable of. :)

     

     

     

    Paramotor weight

    in General paramotor discussion

    Posted

    Steve, I did look at the Maverick at Parafest. It was same weight as the AC200, but had no reserve or prop on it.....so heavier!

    Also, I have had loads of problems with Parajet:

    - 3 months of no machine when first delivered because it would not run properly - 3 replacement carbs, followed by return to Polini. Machine will still not restart when hot ie it cannot be turned off in the air as it will never start again.

    - Machine damaged when then sent back to me - both cage attachment points bent through 90 degrees.

    - Replacement prop took 6 weeks to arrive - it was sent to wrong address.

    - Live wire to starter 'fell off' and shorted out battery - new battery was with replacement prop!!! Starter wire now has insulation melted off where it shorted.

    - Starter stopped working - broken winding. Waiting for replacement now.

    - And at Parafest I noticed that the starter wire has snapped off again.

    All that in just 10 months, 35 flights and 21 hours! Much of that maybe due to Polini crap carb, but I would expect a new machine to run properly when first delivered. :(

    Paramotor weight

    in General paramotor discussion

    Posted

    Thanks Vince...... Calcs are..

    Momentum in moving unit P =  m x V

    Change in momentum = average force x time = f x t / 2 which has to use up all of the momentum so f x t /2 = m x v

    or, after rearranging, impact f = 2 x m x v / t

    You have assumed 1 second impact time, which is a lot. In this time you travel about 5.5 m

    Probably more like half a second on soft ground and 0.2 second on hard ground....which for 20 kg and 11 m/2 gives

    880 Newtons or 90 kg

    and 2200 Newtons or 224 kg

    This why soft ground is so important!!!!!!!

     

     

    Paramotor weight

    in General paramotor discussion

    Posted

    I really appreciate your views guys. This is where I have got to:

    I flew at Parafest in the gusty conditions with no problem.

    I have been flying 10 months, but being retired get to fly quite often - 35 flights now and 25 hours.

    In the 35 flights I have only failed to launch first time on 3 occasions.

    Every launch I have done has been forward, as this is easier for me (I walk with sticks cos I am wobbly and turning round from reverse is not good). I have forward launched in 10 mph with my 28m wing (lean long way forward and allow myself to step backwards 4 or 5 steps as wing comes up).  Not counting the backwards steps this gives a one step forward launch.

    My arms are longer than the v3 cage.....the risers do not touch the cage, so I guess this would help with 'flimsy' cage?

    I have flown in very rough air and during the day in the heat of southern Spain.

    Landings. All but 1 landed on my feet, but on 4 of them I went down on 1 or both knees. My second flight I landed on my elbow, which protected the cage nicely!

    Because I fly on my own, I am always reading the PPG Bible so I can try and practice something a little more every flight. I don't foot drag yet, but I can fly 5 foot up along the beaches. Am I being over confident wanting to go to a super light machine, or would this be OK?

     

    Paramotor weight

    in General paramotor discussion

    Posted

    Has anyone really looked at the total weights claimed for machines and checked them?

    I was chatting with our Air Conception man at Parafest and picked up his machine with a 200cc engine - with both reserve and prop fitted. I picked it up easily with one hand - no fuel.

    Most of the other machines on display had no reserve and in some cases no prop. They were all heavier.

    Meanwhile, I struggle to move my own Parajet V3 machine with both hands and I never put over 7 litres fuel in (too heavy then). When learning I was advised to go for the strong frame initially as it would take the knocks, but as it has turned out, it has no knocks (I usually bash some part of me instead :( ).

    So I went to Parafest with an aim to look at trikes as I struggle with weight on my knackered back (due 3 more disc replacements this summer). I ended up realising that some machines are now so light that they are a much better solution than the trike.

    Has anyone else tried these 20 kg machines? What are your thoughts?

     

     

     

    Suspension Trauma paramotor tandem.

    in Safety Matters

    Posted

    Wow. I wasn't aware of that and I also have issue with getting in my seat. I'm 6' 4" and was a very tight fit in my seat 18 months ago. The harness just aint big enough. I used to have to wait till I got a bit of height and then have a fight with the seat! I can now get in easily as the seat/harness has stretched a little since new and I have lost 2" in height. :)

    paramotor torque

    in Paramotor trikes / quads

    Posted

    Just a thought guys. I am thinking as an engineer, not someone experienced with hang points. I have now read 5 different ways of easing motor torque.

    1. The best would appear to be static "blades" built into the frame, that deflect airflow the opposite way to the prop. This eliminates torque steer at all motor speeds.

    2. I have Parajet, which use a side-ways offset on the hang points. My machine pulls right, so both hang-points are offset to to the right, which puts mine and machine weight to the left of centre. Only works well at cruising revs ie. at take-off requires all my weight to the left and some left brake.

    3. Lengthening a hang point. This means the non-lengthened hang point is pulled lower, so like weight shifting to that side. Also only works for one engine speed.

    4. Motor mounts longer on one side. This places the thrust at an angle to the wing, so causing a turn. This would provide greater turning thrust as engine rpm increases, so should work across the rev range.

    5. Moving a hang point more forward of the other one. This is the same as 4 above, putting engine thrust at an angle.

    The last 2 worry me a little as I watched a video of a machine with option 4 taking off and he managed to nearly twist the risers right round, lost forward speed and dropped 15 feet into the ground. 

    What are your experiences with any these? 

     

     

     

     

    A simple question

    in Paramotor trikes / quads

    Posted

    Just for info. Skyschool already do Trike training as many of their customers are outside UK....where Trikes were already allowed. Follows APPI training programme I believe. 

    There has been quite some publicity re their veteran with no legs that learnt on trike then flew some big challenges like John O'Groats to Lands End!

    THE SKYWAY CODE

    in Safety Matters

    Posted

    Great doc. I wish others would do the same. So far in discussions with Spanish Air controllers I have managed to find that PPG is not included in anything! They did point me to a Royal Decree for micro-lights, but then in the small print we were excluded as not being a midro-light!

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