SurfBird Posted December 17, 2011 Share Posted December 17, 2011 (edited) I'm considering buying a Top 80 based paramotor and friendlier reflex wing such as the Revo2, Thrust HP, etc. but am concerned about the motor running at full speed to maintain level flight with trimmers out. Add the speedbar and how much thrust will I need? Is there a formula to calculate x thrust counteracts y sink rate? If I knew the thrust required for a given sink rate then I could make a decent guess at the throttle setting for a given engine's max thrust/rpm. Does anyone have a first-hand example? Maybe you weigh 72kg (me) and fly a Miniplane with an Ozone Roadster that can maintain altitude with 3/4 throttle or something like that? I can buy gear once but don't really have the money to screw it up and have to live with something I hate. John Edited December 17, 2011 by Guest Quote Link to comment Share on other sites More sharing options...
nigel_d. Posted December 17, 2011 Share Posted December 17, 2011 I have a pap top80 with 125 carbon prop ( for sale as it happens) and I weigh 80 kilos. It flies my 31 Nucleon on fast trim at about half throttle doing 29 mph. On full throttle it climbs at about 130 ft/min. On full speed bar it can almost maintain level flight however on tickover it's a great rapid decent method, about 700 ft/min. Hope this helps Nige Quote Link to comment Share on other sites More sharing options...
matt_k Posted December 17, 2011 Share Posted December 17, 2011 Im 65kgs and fly a Top80 125 miniplane with a 24m revo and theres bags more power for me if i need it in full refrlex, never used my speed bar though, but im getting aroung 2.5-3ltrs and hour Quote Link to comment Share on other sites More sharing options...
SurfBird Posted December 17, 2011 Author Share Posted December 17, 2011 Excellent info! That's just the sort of examples I am seeking. I have been reading this forum for some time and really appreciate all the great input from you. I don't expect to spend much time on speedbar so I can live with a "high speed slow decent" if needed. Just don't want to burn out the engine by running full out most of the time. Anyone else? Quote Link to comment Share on other sites More sharing options...
markpulling Posted December 17, 2011 Share Posted December 17, 2011 Yes same for me ,top 80 with 26m revo,I weigh 75kg ,I very rarely use FULL throttle even on climb out !! Quote Link to comment Share on other sites More sharing options...
lukebanks1 Posted December 17, 2011 Share Posted December 17, 2011 SurfBird, I have a Miniplane Top 80 and a PAP Top 80 (For sale) I weigh 85kg and fly it with my Nucleon 29. On Full bar (with pulleys just overlapping) I can maintain level flight on the PAP (125cm prop) and climb on the Miniplane (130cm Prop). At your weight the Top 80 is perfect! See my advert for the PAP in the classifieds section Quote Link to comment Share on other sites More sharing options...
SurfBird Posted December 17, 2011 Author Share Posted December 17, 2011 Not to hijack my own thread or anything but since you brought it up... I still have to decide on what size prop and am having trouble finding information. I know that, in general, a larger prop generates more thrust so can turn at lower rpm and better fuel economy. Sounds great right? What's the downside? Why doesn't everyone run the biggest prop they can hang on their engine? Is it the larger cage size causing difficult launches or what? Thanks for the useful replies everyone. John Quote Link to comment Share on other sites More sharing options...
SurfBird Posted December 17, 2011 Author Share Posted December 17, 2011 Just found this thread covering the same subject on another board for anyone who might be interested... http://groups.yahoo.com/group/top80/message/4233 Quote Link to comment Share on other sites More sharing options...
matt_k Posted December 17, 2011 Share Posted December 17, 2011 I had a top80 pap 1250 with a 115 prop and upgraded to a miniplane top80 1380 with a 1250 prop and was a bit worried about forward launching a larger cage being only 5'5" with little arms and its no problem Quote Link to comment Share on other sites More sharing options...
SurfBird Posted December 17, 2011 Author Share Posted December 17, 2011 If cage size is my only worry then I should be fine at 6' with long arms! I want the extra thrust of the 132cm prop but want to know the downside before purchase. Why do most people seem to choose the 125cm? I've only had a few flights so far but takeoff was easy once I got the wing up (forward launch needs more work). All my flights have been on a Nirvana Rodeo. It had no problem tossing my skinny self into the sky like a rocket but I want to go lighter! Should the prop size discussion be a separate thread? Quote Link to comment Share on other sites More sharing options...
christian Posted December 18, 2011 Share Posted December 18, 2011 Miniplane Top80 125 prop & Roadster M. I'm 85 Kgs. I have no problem maintaining altitude on 1/2 to 3/4 throttle. Good luck Quote Link to comment Share on other sites More sharing options...
savage Posted December 23, 2011 Share Posted December 23, 2011 Whilst the 125 prop and std cage will be absolutely fine for you, as you suggest, why not go for the bigger prop/cage and get better efficiency/thrust with a bit less noise at cruse. There is no disadvantage with the XL cage. The prop to go for is new T2HA carbon in 130cm on a 19/73 gearbox, you could go for the 135 carbon, but i think it's a step too far being very close to the cage and only really for competition use, also the new T2HA prop is a totally new profile that Diego did a lot of testing on to improve it's efficiency over the previous version, i think it's output is very close to the 135, also the 135 is horrendously expensive. If you want all the power you can get, don't go for an inefficient wood prop unless you think you are going to break it. FYI I still climb at about 150-175 feet/min on full fast with full bar. Stuart 78Kgs. XL MIniplane, 130 T2H prop. 28 Gin Airflex If cage size is my only worry then I should be fine at 6' with long arms! I want the extra thrust of the 132cm prop but want to know the downside before purchase. Why do most people seem to choose the 125cm?I've only had a few flights so far but takeoff was easy once I got the wing up (forward launch needs more work). All my flights have been on a Nirvana Rodeo. It had no problem tossing my skinny self into the sky like a rocket but I want to go lighter! Should the prop size discussion be a separate thread? Quote Link to comment Share on other sites More sharing options...
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