Jump to content

paramotor torque


raglan
 Share

Recommended Posts

Hi all any info would be gratefully recieved  

I have been flying my trike which is a weight shift type ( i will try and insert a photo )

with a pap ros 125 engine for a while now and because of a wing change I decided to get a bigger motor 

so I now have a simonini mini2 EVo in a PXP weight shift frame sopposedly built for a evo2 engine its blisteringly quick on the ground during testing 

However on takeoff I was not very happy it veered  dramaticaly to the right ( trims neutral apco lift ) I had to weight shift as much as I could possibly do i.e. hanging out to the left and also pull some left brake not what I wanted to do as I was waiting for it to spin ......I managed a very nervous circuit and landed 

people seem to be giving me different advice and I am aware of only one thing my head is about to explode i thought I knew sorting about torque but Now I am just confused 

so  if its viewed from the harness side of the paramotor i.e. looking into the seat the engine is a belt drive and its turning to right i.e. clockwise the frame has a longer offset to the left which is supposed to stop the torque ............whats going on is the offset on the wrong side or have i got another problem once the power is off the drama stops and all is as it should be 

one thing is certain until I get to the bottom of the problem I won't be flying it again ..as I reckon I was very close to a visit to a hospital 

Link to comment
Share on other sites

If the engine is clockwise looking from the front, then the torque is ant-clockwise...so trying turn you to the right...same as my Thor 190.

My harness has both the hang points off-set to the right to counter this.

On yours, by a longer off-set do you mean it puts the engine at angle to the direction of travel? And is your longer off-set to the left...still looking from the front? ie when sat in it, is the longer off-set on your right?

Link to comment
Share on other sites

ok  as I am sat in the harness the longer offset on my frame is to the right and the propeller is going i.e. spinning behind my head from my right side to my left

the confusing thing at least for me is do we look at the front i.e. from the harness or from the rear from the engine ????

like I said before the whole paramotor was trying to turn me to the right hand side very badly it carnt be anything to do with the wing as its flys ok with the pap and is fine when the Evo is off the power ....

Link to comment
Share on other sites

I have torque effect in the opposite direction on my trike, although nothing as severe as your experience. It has been suggested that I could shorten the brake line by an inch at a time until it flies neutral, but I feel reluctant to do this as the wing would be out of trim on the ground and I would have no ability to let the brake off if needed. 

I have flown with a little right brake pulled to keep it straight and might even consider adding a little weight to 1 side of the trike to compensate although this will upset the completely neutral trim for a powered off landing.

Has anyone else come up with a solution?

Link to comment
Share on other sites

As no one else has replied. ...

Guy.

Never shorten the brake line to compensate for torque! Whoever told you that needs taking out and shooting!

Can you move one hang pint up or down, 10mm? If not, can you can move one 10mm forward or back? For a left hand turn, move the right hang point back 10mm or, left fwd 10mm and test fly and adjust as necessary.

Raglan.

You have gone from a gearbox motor to a belt motor, this usually (but not always) means the prop spins in the opposite direction. If this is the case, then all your torque compensation will be adding to the torque rather than reducing it. Unless you can swap the arms over, or buy arms with offsets in the other direction,  you will have to get some arms professionally made to suit. 

Link to comment
Share on other sites

Hey thanks for the replys rest assured I won't be shortening any brake lines !

No the frame I am using is supposed to be for the mini 2evo it was bought from pxp in spain direct.....its not in the pap chassis

the off set  (( according ))  to Mr PXP is correct and it is built into the frame ..on the pap you can flip the arms over to alter the offset but on the PXP the arms are straight and its 

offset is only on the frame ...and as I sit in the harness the longer offset is to my right perhaps I can spacer out the arm more to the right ( if thats the direction I need to go )

i.e. with a longer bolt of course but I could do with knowing which side needs to be altered ? I am not sure and as it stands its pretty much un flyable 

Link to comment
Share on other sites

Thank you for your good advice Savage, and rest assured that like raglan, no brake lines will be shortened on my watch!!

I might well be able to move one hang point up 10mm. If I have a turn to the left, presumably it is the left hang point which is the one to be raised. Am I right?

Many thanks,

Guy

Link to comment
Share on other sites

Sorry fellas, been away in the Alps for the long weekend.

Guy. Yes, you are correct to raise the left hang point for a left turn. It's a compromise because it will induce a slight right turn when you are power off. You may find you prefer moving the left hang point forward 10mm (if you can) as this won't cause a turn when is power off or, a combination of both (but one step at a time). FYI. If you have a swing arm with holes that are an inch apart, you can fit two shackles into two adjacent holes and this will give you a hang point between the two, just satisfy yourself that the two shackles are long enough that they don't try to unzip the stitching of the fabric loops that go to the carabiner. 

Raglan. It sounds like the offsets are in the right direction. I would avoid spacing out the right-hand swing arm bolt any further as they are already under a lot of stress (in the wrong plane) and it would only make it worse. Can you not move left hang point back one hole (about an inch)? Rember, power off it will still fly sraight, so if you are not happy, reduce the power and land.

Hope that helps.

Stuart.

(I take no responsibility for my advice and any adjustments you do at your own risk. Obviously, it would be better to take your machine to someone who can actually see your set up, adjust it and test fly it for you).

Link to comment
Share on other sites

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? 

 

 

 

 

Link to comment
Share on other sites

Thank you Stuart, and I take full responsibility for this (as for most things in life). My head was doing a bit of brain fade on the subject and you have provided much needed clarity.

Hope the Alps were good.

Best wishes,

Guy

Link to comment
Share on other sites

2 hours ago, AndyB said:

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? 

3

1. I haven't flown this type, so am still to be convinced. If it's not a sales gimmick, they will add a reasonable amount of drag, especially if you like to 'motor off' thermal and AFAIK, they still employ riser offsets and moving swing arms on the Scout to counter torque. (happy to be told otherwise though).

2. Try 5.

3. Agreed and was/is mostly used for fixed, rather than moving swing arms.

4. I am sure it's never been done, it would put the prop well outside the cage on one side and very close to the cage on the other.

5. Works very nicely. It's how I fly my Miniplane Top80. I increased the fore/aft offset still further when I fitted a Sky110s, again it worked nicely. I also flew my old HE 120 with one hole difference either side on the swing arms, again it worked well. Power off and it flys straight, add power and the slightly offset thrust line has a tendency to be straightened (perpendicular) to the wing, not the other way round. Get the fore/aft offset the wrong way round and yes, you could easily end up twisted, as per your example. The old powerful Walkerjets were notorious for twisting as they had little or no torque offset and fixed arms. Remember, smoothly come off the power, if you feel the motor twisting under the wing and it will straighten out (better to have a heavy landing than a twisted, stalled, backwards, power on, landing).

With wing turns, if you think of the wing as a broom balanced, brush up, on your palm. Walk forward, balancing the broom. If you now offset the thrust, you can sort of see where the wing is going to turn.

Stuart.

 

  • Upvote 1
Link to comment
Share on other sites

  • 1 month later...

I own a simonini mini 2 plus belt drive....looking from the back the prop rotation is anti clockwise. The paramotor turns to the right in the air.

 

The torque problem is one reason why weghtshift trike/buggy are a bad idea. My understanding is high hang point is much better for this.

 

I am not a fan of changing your caribiner positions fore and aft assymetrically. If you have a major wing event this is going to make recovery more difficult...you are better off altering the sidethrust of your engine the same way it is done in all other forms of aviation.

Anti torque fins on the cage really do work...and have been well proven, however, they need to be designed for the unit...just randomly throwing on aftermarket crude is a waste of time.

 

My biggest observation here is that you have gone from a very small low torque engine to a big one. That in itself is like going from an en b free flying glider to an en d 2 liner...big big step up. You really should footlaunch the bigger engine for a while to get used to its considerable power and torque.

Finally, with torque steering;

1.  slow speed and high angles of climb.  Keep the climb angle shallow and speed up.

2. Propellor angle in relation to the vertical iscritical...your prop needs to be as close to vertical as possible...having a big engine with too much angle, (thus producing up thrust) not only unloads wing, it exascerbates torque steering. You have now got a considerably heavier(18.5kg) motor behind center of gravity. Did you hang test and measure prop angle before flying?

Personally i would piss off the weightshift..a trike/buggy does not need weightshift. 

Edited by adamjedgar
Link to comment
Share on other sites

Ive now sorted the problem 100%........

I have now found the solution to My problem I Bought a new Pap Moster stuck it on the trike and Boooooom it now flys straight no twist no worries sometimes it pays to get some one who knows all there is to know about paramotors to do the job correctly especially when your life depends on it 

Image 26-07-2017 at 12.52.jpg

Link to comment
Share on other sites

Don't know ?  

 I have perhaps taken a drastically  unothadox solution and at the cost of quite a few pennies !  But the result is I can now fly safely 

both props turn the same way and use the same size helix props both weight shift ....one engine 25hp the other 30+ ...so around 5hp more but a totally different flying experience

I am sure its not just down to the Hp

anyway onward and upward proplem solved

 

 

Link to comment
Share on other sites

I am just reading AdamJedgar response ....Hey thanks for the input but I couldn't disagree more ...I have always flown weight-shift and apart from a few test flights with high hang points in which I just didn't feel .....the feel  ? ? if you get what I mean  !

So I will probably always continue to fly weight shift  they just suit my style of flying,  I Likke them ....I can weight shift on the trike just as well as I could when foot launching it only weighs 13kg ...and unfortunatly foot launch isn't a option anymore due to a accident 5 years ago I am just glad Ive sorted the problem out now and can look forward to some epic days paramotor flying again 

Link to comment
Share on other sites

On 6/21/2017 at 21:41, Guy said:

I have torque effect in the opposite direction on my trike, although nothing as severe as your experience. It has been suggested that I could shorten the brake line by an inch at a time until it flies neutral, but I feel reluctant to do this as the wing would be out of trim on the ground and I would have no ability to let the brake off if needed. 

I have flown with a little right brake pulled to keep it straight and might even consider adding a little weight to 1 side of the trike to compensate although this will upset the completely neutral trim for a powered off landing.

Has anyone else come up with a solution?

my trike turns left on t/o i just open trimmer haft inch while turning then flys straight,always go with the turn,dont use opp brake or spin/stall may happen,you could offset one risers slightly

Link to comment
Share on other sites

33 minutes ago, jock said:

my trike turns left on t/o i just open trimmer haft inch while turning then flys straight,always go with the turn,dont use opp brake or spin/stall may happen,you could offset one risers slightly

Hi Jock. I've gone with the offset riser 10mm. Like you my rotax turns to the left under power so I have moved the left riser forward by the 10mm (heads up to Savage for his help on this).

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share



×
×
  • Create New...