PDA

View Full Version : Engine selection



wayne giles
08-10-2008, 02:06 PM
for the kitfox sport .all indications are that the rotax 912uls is most suited for the airframe.whenever i hear one shutting down the sound puts me off a bit .does this put any strain on the airframe or gearbox.
are there any published results using a io 240 or the jabiru engine

Jorge&Cindy
08-10-2008, 02:52 PM
When I visited the factory they had Jabiru engine there. I was told they didn't care for it do to cooling problems.

jdmcbean
08-17-2008, 02:45 PM
Wayne,
Track record really speaks for itself.. The Rotax 912 has a 1500 TBO and they are reaching that and way beyond on a regular basis. I know of some that are at 2000 hours and still producing 78 to 80 /80 compression. They are the most popular engine choice in most light aircraft aircraft. We have not seen any issues regarding the shutdown since the addition of the slipper clutches... which is standard in the 912ULS today. The Jabiru 2200 has a good track record while the 3300 has been battling temp issues. There are but a handful of the 3300 in Kitfox's one particular I will be watching pretty close as he has a history with the engine in another airframe and the customer has owned the engine since new. Facts are that the performance is better with the Rotax 912ULS then the 3300 from the data we have seen. The IO-240 is a good engine and I have some time behind it in the Kitfox. Although it has 125 hp the empty weight of the aircraft tends to be in the 975+ range with most right at the 1000 lbs. vs the 800 lbs average on the Rotax powered aircraft.
Lycoming O-235 and the Continental O-200 engines have also been used with most of the empty weights coming in around 900 to 950 a couple of them have been built at 870. Hope that helps.

wilson1steve
08-17-2008, 05:44 PM
Many in our parts are keeping our fingers crossed on the outcome of the new Lycoming IO-233-LSA. Would be great to have an American option with support galore.
It sure looked great at Oshkosh on the display.

jonbakerok
08-18-2008, 05:05 AM
John, does the factory have any performance charts for various engine options (and in my case, the IV as well as current model)?

I'm still trying to figure out if 80 HP is 80 HP. The VW and Jabiru 2200 get their 80 HP at 3300 rpm, which limits prop size. What's that do to climb performance? Obviously, it must hurt, but at half the cost, the question is how much?

jdmcbean
08-18-2008, 12:08 PM
We are keeping a close eye on the IO-233. Weight, Weight, Weight

jdmcbean
08-18-2008, 12:12 PM
Sorry, I do not have numbers on the VW or the Jab. I can tell you that all the Model IV guys I have talked with claim very simular performance between the 80 Rotax and the 85 Jab. I do not have personal experience with the Jab but can tell you the IV with the 80 Rotax performs wonderfully

jonbakerok
08-19-2008, 05:01 AM
That's good to hear! Especially since a USED jab 2200 popped up on Barnstormers yesterday, about 4 miles from my house. That pretty much settled settled the issue for me, performance or not. Still, it would be nice to see some numbers. Maybe at the next Kitfox gathering you could get some guys to volunteer their planes to test various combinations of model, engine, and prop.

jdmcbean
08-19-2008, 08:33 AM
Be careful that it is the newer Jab.. The older ones I am told did not produce the HP stated and there were some other issues...

KevinM
08-24-2008, 07:42 PM
80hp x 5252/3300 rpm = 127.3 ft-lb of torque to the prop The 80 hp Rotax for example ( I don't have the specs in front of me so I may be off a little on the hp and the rpm but you will get the idea) 80hp x 5252/5700= 73.7 ft-lbs of torque. But the gear box at 2.43:1 multiples this to 179 ft lbs at the prop. This allows a much longer prop due to tip speed and a higher pitch due to prop torque. So it will have more take off thrust, top speed will be dependent on pitch, but apple for apples in pitch, it will be about the same.

So yes an 80 hp Aerovee or Jab 2200 will fly a CH 701 (for an example of a draggy airframe) but it will not have optimum STOL performance and it may have over heating issues. Put a redrive on it and you get to enjoy some of the same benefits as the 912, but it air cooled and you may be running even higher rpm, so heat again.

Sorry didn't mean to jump in unannounced, but I have am building a 701 and I found an unfinished Kitfox type 3 so I was looking at engine possibilities and I saw your post. I really like the folding wing option!
Kevin