Paramotor weight

[AndyB]

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?

 

 

 

[Neilzy]

I have a Nitro and suffer from bad back knees I'm over weight 120kg, unfit and 55yrs old. And was going the same trike route then the AC Nitro came along, and for us unfit older types a complete game changer 

[powerlord]

yup I've got a nitro too (with clutch and leccy start).

though I'm not anti heavy motors if you get something for the weight (lots of power, lots of strength, etc) most of the cases you don't get that.

It's hard to beat the nitro for power to weight. the cage is not as strong for sure, and is a bit of a faff to put together (though no more than other light weight jobs like the miniplane), but I do notice myself that I have no compunction at briming the fuel to the top of the tank and still walking 100 yards with the motor on my back and carrying my wing, helmet, etc.

I can't say that's the case with any other motor I've had other than my pap top 80* (bailey v5, pap top80, parajet volution, castelluccio fly 100).

And I have weak knees (had 4 cruciate ligament reconstructions), so unless I get landings completely smooth, if they are a wee bit hard I end up on my arse rather than risking my knees. My arse/feet ratio was maybe 50%.

With the air conception so far (10 flights) it's been 90%. So it does make a difference for sure.

stu

*I think even the top80 was 3kg heavier. 

[cas_whitmore]

I have a AC 130 race addition , it's effortless to carry around ,. My miniplane is light but heavy compared to AC .

cas . 

[AndyB]

Thanks for the feedback guys. I just emailed Vince for delivery time!  

[Nighyiun]

You can give us more examples of the issues raised.

[admin (Simon W)]

I just wish they had a stronger cage. (strong enough to do a powered forward launch at least). I find it hard to recommend a machine to a new pilot that requires the extra care and thought during early launches. Not to mention the possibility of some less than ideal landings in the early days... 

I personally, also don't like the way the arms are attached to the frame. Although I know of no faults in the area, I still don't like it. This is something that can be improved with ease but it would then weigh an extra 100g or so... and so on...... In a nut shell, in my opinion, they have sacrificed too much strength to get to the lighter weight. 

There is light, and there is light and 'flimsy'. 

I genuinely don't think it's the machine for a early pilot for these reasons. 

SW

 

[cas_whitmore]

 i think most raw beginners would struggle with a flexible hooped frame I did at first ' as I learnt on a pap frame . So I could power launch with that' but say someone who's flown paragliders I guess would be ok .  But for a second machine after some hours learning should be ok . have to get your landings sorted as well .

cas. 

[custom-vince]

I would go the other way and say its actually perfect for beginners being lighter, with correct teaching its safer, easier, faster progress. Maverick is similar design, do not be afraid to let beginners on it. They are less likely to stumble and the titanium proves very robust for all but the biggest spills..

 

Watch these guys, they do OK, not only new pilots but teaching using the AC nitro. Its a great video to show exactly what happens for first time paramotor pilots.

 

 

 

[AndyB]

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?

 

[custom-vince]

As I am the dealer I would encourage other views. The cage is not flimsy as you had a feel yourself. I regularly power launch, I'm not someone who takes steps back and does a full power run at it, i am typically 1/4 and 1/2 throttle power launching, letting the machine do the work not me. I have had a few slips and accidents over the time, its all part of it if you fly enough and push the conditions a little. There is even a video of me doing wing tip drags till I hit the ground, netting was damaged but nothing else. Prop good, frame good, carbon spars good. I slid on the grass on full throttle with hard turn at full speed.

 

The miniplane guys have been saying it for years, lighter weight = far less chance of a miss-hap. Also the energy involved in a slip is far less.I forget the formula for speed vs impact.

http://calculator.tutorvista.com/impact-force-calculator.html

 

25mph is 11m/s

20kg at 25mph for 1seconds is 440nm impact

30kg at 25mph for 1 second is 660nm impact

 

a poor example but an example none the less, the point is with weight the initial impact is amplified. This can be in an accident or on your feet.

If you have the space you can go trike or go light. Trikes are not so hot on soft sand. Worth talking to someone who flys trikes to get a good comparison. Also worth noting, owners views are more important than onlookers. What ever the machine, get opinions from actual owners.

[cas_whitmore]

My frame has 12mm hoop are the newer ones 16mm which I guess would stiffen it right up . 

Cas . 

[AndyB]

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!!!!!!!

 

 

[powerlord]

strength of cage is a difficult one.

I broke loads of props in my parajet volution - and that has a very strong cage.

But all the engines are on rubber mounts - in the bump to the ground the prop will come into contact with the cage and smash it.

same for every other paramotor I've owned.

Even my old JPX330 1.3m which had a double loop cage - lots of clearance, but in a crash, you'll still lose the prop.

So for me cage is about protecting ME from the prop, not the prop from the cage (or ground).

And that's not about cage strength as much as good design - the original volution being an example of terrible design for example - you can fit yer fist through it

So for that, it does a decent job* - it's pretty solid all up. A bit more flexible than the bailey v5 or PAP cage, but not much. Certainly nothing that would stop power launches I'd have thought - though personally I don't do em and have never seen the point.

What might stop power launches is that there's not a vast amount of clearance between the prop and the cage - the prop sits outside the cage like most single rings, but it's pretty close to it if you were insisting on power launches. But no more so that some other paramotors.

As suppose adjusting to not power launch would be the solution there.

I agree with Simon about the arms - I don't like em either - using a hardened bolt in sheer load is not a great idea. They are not meant for that. There should be a full length mild steel cylinder washer over the length of the connector like the PAP. mild steel sleeves bend, harndened bolts snap - that's why hardened fasteners are not used for large sheer loads in most engineering applications. However saying that - I bumble about the sky so they are never likely to face any significant loads, but it's an easy fix and 'it's never had a problem so far' is not an answer for a basic engineering mistake.

*I have also changed one thing - which is that the netting left massive gaps at the bottom of the cage each side - imho this is precisely where your hand is most likely to be dragged into the prop via the throttle cage, etc** - and unlike above the cage, your arm movement is quite happy to let that happen... So I thread up the cage with the tightener BELOW the bottom side frame cross struts rather than above them - this leaves a smaller gab - I then use 2 velcro straps - one each side across the remaining gap - this stops the thottle cable having any chance of going into the prop and/or my hand or arm.

**and I speak from experience as thats exactly where my hand did try to be dragged in on my castelluccio, and it was only because the strap around my wrist broke once my hand pushed against the bottom netting that means I still have 2 hands.

However , other than that I've so far found taking the cage apart and putting it together far less of a hassle than I thought it would be - once you get used to it it take less than 5 minutes each way (I timed it). And unlike the bailey I can leave the prop on and fit in the motorhome, so I save time there - overall I think it's about same set up time as the 4 part bailey + putting prop on.

Weight wise though there is one other thing to bear in mind and that's fuel consumption. With my top 80 and my v5 I pretty much never used for than 2.5l per hour. So usually flew with 5 litres in there knowing I had enough for 2 hours whatever i did and I never fly longer than 2 hours.

The nitro is far far thirstier, and far more variable too depending on what I'm doing - so I can only be sure I'll get 2 hours by sticking 10 litres in there. that's an extra 4kg or so of fuel I'm flying with, which is somewhat offsetting the weight savings I suppose.

Overal though I AM getting that extra 10-15kg of thrust for the same of a bit less weight (fuel adjustment made). That's probably made a bigger difference that the weight to successful takeoffs I think:

1. need less space, less running, more take off sites possible

2. if i do screw it up, the light momentum of the prop and top of the cage make it much easier to stop running, stop engine, etc and not end up falling and damaging something. Probably the very light prop has quite a lot to do with that - the momentum and gyroscopic force of a bug old wooden prop probably leads to lots of fails aborts (i.e. aborts that end up in you falling or prop damage, etc)

 

[raglan]

Much better solution than a trike ???? why is that nowt easier than just opening the throttle I don't even enjoy the odd face planting these days

[Steve]

Have a close look at the Parajet Maverick, it's beautifully engineered and proving to be a great combination with the Moster engine. Plus you get the best customer service around. 

 

 

[AndyB]

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.

[Steve]

Sorry to hear about your problems Andy - I don't think Polini have done paramotoring manufacturers many favours over the years with bad designs and worse customer service. If I owned a Polini (I do) I'd rather it was in a Parajet machine as they do take proper care of you.

The Moster/Maverick combination is in a different league to the old Polini combinations. 

[AndyB]

Yep, Polini not great. I had another machine (same before it was knicked) and it worked great.

[cas_whitmore]

polini's reputation is the only reason apart from moneys I haven't owned a parajet '

Cas . 

[custom-vince]

14 hours ago, powerlord said:

I agree with Simon about the arms - I don't like em either - using a hardened bolt in sheer load is not a great idea. They are not meant for that. There should be a full length mild steel cylinder washer over the length of the connector like the PAP. mild steel sleeves bend, harndened bolts snap - that's why hardened fasteners are not used for large sheer loads in most engineering applications. However saying that - I bumble about the sky so they are never likely to face any significant loads, but it's an easy fix and 'it's never had a problem so far' is not an answer for a basic engineering mistake.

*I have also changed one thing - which is that the netting left massive gaps at the bottom of the cage each side - imho this is precisely where your hand is most likely to be dragged into the prop via the throttle cage, etc** - and unlike above the cage, your arm movement is quite happy to let that happen... So I thread up the cage with the tightener BELOW the bottom side frame cross struts rather than above them - this leaves a smaller gab - I then use 2 velcro straps - one each side across the remaining gap - this stops the thottle cable having any chance of going into the prop and/or my hand or arm.

**and I speak from experience as thats exactly where my hand did try to be dragged in on my castelluccio, and it was only because the strap around my wrist broke once my hand pushed against the bottom netting that means I still have 2 hands.

----

Weight wise though there is one other thing to bear in mind and that's fuel consumption. With my top 80 and my v5 I pretty much never used for than 2.5l per hour. So usually flew with 5 litres in there knowing I had enough for 2 hours whatever i did and I never fly longer than 2 hours.

The nitro is far far thirstier, and far more variable too depending on what I'm doing - so I can only be sure I'll get 2 hours by sticking 10 litres in there. that's an extra 4kg or so of fuel I'm flying with, which is somewhat offsetting the weight savings I suppose.

 

Hi Powerlord I have some feed back and solutions for you to consider.

I haven't heard of any cases on the AC but from experience, If you are concerned about the throttle cable entering the prop area there is a simple solution that a friend showed me. Have the cable going over your arm to hand throttle, not under your arm, super simple and super safe.

I just removed the bolts from a 200hours machine which is used fairly hard with GTS16m wing. no signs of wear or damage. The bolt is not under a shear load as such, that is what the load dispersing discs are for, the transfer the loads into torsion, if the bolts were loose on had spring on the back, then it would be more shear loading. The bolts also take 25% of the landing with a breaking strain greater than your carabiners.

If you are finding your nitro thirsty, give me a shout. There are solutions. Fine carb tuning and angle of flight has an effect.

Hope that helps put your mind at ease.

[AndyB]

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.

 

 

 

[custom-vince]

Well Andy B, what can I say. Thanks noticing and thanks for taking the time to talk to us at parafest, heres some videos, just for fun.

 

I made this one as 20kg doesn't sound much different to 24 or 26kg, this is the best way I could show it, as I know I certainly can't lift other machines in this way.

 

 

This video was trying to show there is no trickery, nothing missing. We do a lighter unit with split leg soft harness and soft fuel tank at 18.8kg with stronger 16mm hoop, with the same nitro engine.

 

 

Heres another with the pull start. Most new ones are sold electric start, but as you can see I have no issues pull starting mine. Key points are good spark plug, correct belt tension, if all is good they are easy to start.

 

 

[powerlord]

2 hours ago, custom-vince said:

Hi Powerlord I have some feed back and solutions for you to consider.

I haven't heard of any cases on the AC but from experience, If you are concerned about the throttle cable entering the prop area there is a simple solution that a friend showed me. Have the cable going over your arm to hand throttle, not under your arm, super simple and super safe.

 

yeh I did that Vince, but I still prefer to have summit there to stop my hand from getting sucked into the prop frankly. It was an easy mod to make. Takes no time to do when assembling. I post only so others can do if they want - no permanent modifications required.

For example - aborted take off, prop on full power, you lose your balance and can't press engine stop, hand goes down to ground to brace you, and could easily go thorugh that hole.. bang.. no more hand. If they are taking suggestions - that's one I'd say - make the loop and netting such that it leaves no gaps at all at the bottom - I see no technical reason why they can't do that. 

Sheer load wise - I agree with Andy - I still think it's mostly a shear load - though he seems to know more about this stuff than me so I'm only speaking from what I see ? And no safety straps if it fails. Jeff Goin (of paramotor bible fame) made the same comment when he reviewed it. In fact he made the same comment about the cage netting too reading it again:

http://footflyer.com/Equipment/Paramotors/2016/AirConception200/Paramotor-review-Nitro200.htm

Not saying it's unsafe or having every caused problems, just saying it's a machine of compromises (like every other machine every built) - and that's one of em. Personally I'd be happier with a sheathed bolt or spigot/grommet type design and a safety strap for the sake of 200g or so - especially considering at least 2 deaths in the UK (not on air conception machines!) were due to the swing arm mount sheering (albeit under extreme load during acro).

As I say, every machine is a compromise - has it's pluses and negatives. I like my nitro. But like every other machine I've ever owner, or car, or bike or motorbike or whatever - there's gonna be things that don't suit you. I just though it worth pointing out the cage/netting one so others could fix it if it bothered them. Arm wise - as I say - since I bumble about the sky like a sunday driver I can live with it.

fuel economy wise it's as I expected - I think some of it is that due to the extra power I probably lose and gain height more during flights now too, since it's easier. Not an issue. Once I've put some more miles on it, I'll see if she's running rich, but for now, happy to keep sticking fuel in it rather than buggering about with anything tbh.

To come back to the prop, I think a super light prop is probably more important that we usually give credit to for making the machine easy to handle. During changes of direction during launch, aborted take offs, etc,etc I really notice the lack of gyroscopic force over something like the much heavier Helix type. And vastly lower than big old wooden ones. If someone is struggling with an unweildy machine, they might find fitting a lightweight e-prop like on the AC (and other modern machines) helpful.

stu

[AndyB]

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.