Flying Bozo Posted January 1, 2012 Report Share Posted January 1, 2012 I was talking to a person who was looking at a light sport for his future and he took a ride in a Piper Sport. He said it was a real slow climber and asked what it would do when it was hot outside. The person giving him the demo didn't have an answer. I know they are not called that any more but they are still in production under another name. The specs call out a 1200 fpm rate of climb for that plane and the CTSW is called out as 900 FPM. I would like to hear some feedback on these numbers because I can't believe that the Piper can do 1200 even not fully loaded. Here at about 4000 MSL I can see 600 or maybe a little more fully loaded in my CTSW and I suppose that if I were at sea level it might go to the 960 as specified. Some simple calculations tell me that it would take 48 of the available horsepower to lift 1320 pounds up at a rate of 1200 feet per minute. That does not take into account the drag on the airframe from the two sources of drag which I roughly calculate to be about 88 pounds of pull needed by the propeller to fly along at best L/D. The L/D for the CT is about 15 to 1 or so and I don't think it could be any better for the Piper Sport. So this is where I would like to have some feedback. If I give the prop an 80% efficiency then we are only having available 80 HP to do the work and 48 is used up making the airplane go up at 1200 FPM. that only leaves 32 HP to drag it along. Hmm is there something that I am missing or is the 1200 FPM a greatly exaggerated number for the Piper? Larry Link to comment Share on other sites More sharing options...
Jim Posted January 2, 2012 Report Share Posted January 2, 2012 My CT climbs the same as yours. I vote greatly exaggerated. Link to comment Share on other sites More sharing options...
Roger Lee Posted January 2, 2012 Report Share Posted January 2, 2012 The CT can see 1200' pm climb and maybe more under the right circumstances, but it may not be fully fueled and it doesn't have a heavy pilot or two people in it. A 150-170 pilot with half fuel can see that easily and especially on a cool morning at a low elevation. I would bet the Piper Sport is the same. It also depends a lot on the prop setting combined with over all take off weight.. Unless these are defined the rate can be very misleading. All you have to remember when an MFG gives you numbers is: figures lie and liers figure. Some MFG's are better about solid real numbers and like most of us know some aren't very real with some of the MFG's and not just about aircraft. Link to comment Share on other sites More sharing options...
Flying Bozo Posted January 2, 2012 Author Report Share Posted January 2, 2012 I agree with your replys. The quoted figures are supposed to be at gross weight of 1320 and it appears to me that the CTSW comes pretty close to doing the numbers that they say...i.e. 960 FPM although I have never been at sea level with it. Ans yes Roger, I was astounded recently when I only had a little gas in it and myself (220) with the takeoff and climb performance. Larry Link to comment Share on other sites More sharing options...
Flying Bozo Posted January 2, 2012 Author Report Share Posted January 2, 2012 By the way, the Technam Sierra which looks much like the Piper Sport and has the same Rotax in it calls out a 750 FPM rate of climb. Go figure!! Larry Link to comment Share on other sites More sharing options...
Jacques Posted January 2, 2012 Report Share Posted January 2, 2012 I have two Tecnam Sierra here at my airport , ( both with 100 hp) and my 80 hp CT outperform them on climb with the same weight ... must be pilot technique Link to comment Share on other sites More sharing options...
Flying Bozo Posted January 2, 2012 Author Report Share Posted January 2, 2012 Jaques, that sounds about right. The Technam Sierra calls for 750 FPM and the CT calls for 960 FPM. I don't know what would be the difference except the airfoil is so much cleaner on the CT with no rivits and also being true to shape. Larry Link to comment Share on other sites More sharing options...
rookie Posted January 2, 2012 Report Share Posted January 2, 2012 I'm 143# with a rock in my pocket and normally fly with 1/2 tanks. We typically have low DA, often negative. When I first got my LPA I would climb out at 1100/1200 FPM indicated, just because I could . I don't anymore; after hearing horror stories about cracked crankcases due to over torquing I now go out at 750/800 FPM. Also I'm not sure how accurate these indicated numbers are since when I flew to AZ last fall I noted that even at higher DA I could still climb out normally. rookie, Link to comment Share on other sites More sharing options...
Jim Meade Posted January 2, 2012 Report Share Posted January 2, 2012 I did a quick google search on Rotax 912 cranckase over torque and got no hits. Can someone discuss this issue, please? And relate it to the rate of climb? Link to comment Share on other sites More sharing options...
N89WD Posted January 2, 2012 Report Share Posted January 2, 2012 The other day OAT was 26F. My field elevation is 6210 Myself (195) my Dad (205) and 20 gal of fuel we climed at 700fpm @vy with 0 deg flaps up to 11,500'. I belive the DA was 3600' or so. Not too bad at MTOW. Link to comment Share on other sites More sharing options...
Roger Lee Posted January 3, 2012 Report Share Posted January 3, 2012 Hi Jim, There are two types of crankcases that affect us CT owners. If you qualified for the 2000 TBO you have the newest crankcase which isn't as prone to the cracking as the other older ones dated about July 2006 and before and are at the 1500 hr. TBO. What causes a lot of the over load stress is having a prop set up so the engine only gets 5200 rpm WOT like FD and still to this day a few LSA MFG's use and of course private experimental users. FD now and has for quite sometime switched to the 5500 rpm setup. To unload the crankcase you need to see at least 5500-5600 rpm WOT flat and level. You can not do anything about the other rpms since we have a ground adjustable prop. Don't worry about climb if the WOT is set okay. If we were able to use a constant speed prop we could do even better and get the best of all settings. The crankcase crack issue was an SB for Rotax. Bottom line; unload your engine stress points and set the prop pitch to see at least 5500-5600 rpm WOT. Link to comment Share on other sites More sharing options...
S3flyer Posted January 3, 2012 Report Share Posted January 3, 2012 Gotta love winter time for performance. Climbed out this morning at 1000fpm at 95 kts IAS and 40F. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.