Dear builders,

I'm thinking of building another airplane and I'm looking for advice.

I want to have the best STOL performance possible.

My first build, a 701/912uls [450kg mtow] is still flying fine after 13 years and 500 hours. I'd like it to have the latest upgrades though, such as the 500kg mtow, the engine ring mount, new struts, new flap lever, beanie roof and a header tank and new avionics. It might be easier to build a whole new airplane than do all those modifications.

At first glance the 750 STOL seemed to be the one to build, but looking through the forum I'm not sure that it will perform as well as the 701 with the Rotax 912uls engine fitted. My 701 leaps off the ground, cruises at 90mph at 5000 rpm and lands short too.

In a head to head competition with 912uls engine, just pilot on board and half tanks say, which airplane do you think will perform better the 701 or the 750 STOL?

All advice appreciated.

Shay.

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Keep in mind that if you use a 912 and ring mount that you will probably have to give up the tuned intake and so loose about 5 hp. and it DOES matter

It would be tough to beat the 701 due to it's lighter weight. However, the 750 would be tough to be beat for room and performance as a comfortable STOL two seater. Below is a real world video of Chris Browns 750 STOL departing an 800 strip at 4,500 feet elevation, which he also does with passengers with ease. Can't complain about 200 ft departures at  these altitudes. 

https://www.youtube.com/watch?v=Zp6sbLYE0wo&feature=youtu.be

several mentions of upgrading the engine to higher horsepower to increase the performance of the 750. don't forget that a bigger(and likely heavier) engine may not increase the performance at all as compared to the light 912ULS with redrive. the redrive is of course  a big factor in STOL takeoff/climb performance cause we can run such a big prop. I doubt any of the direct drive engines suitable for the 750 airframe will match the 912ULS in TO and climb performance. the 0-200 weighs near 60# more than the 912 and no way it can turn the same prop. I got both engines and tried the blades/same pitch off the 912 on the 0-200. way overpropped...the MP at 2400(that's all it would turn and struggled to do that) cruise was about 30" and the TO and climb rpm were around 2000 RPM. I can't see a direct drive 120 horse Jab being much different except the weight but don't have experience with it so can't say for sure. just something to consider if STOL is a big deal as you indicated.

How about a Rotax 914 with 115hp or the new 915 with 135hp? Both come with the reduction gear. They're a bit heavier, yes, but the 750 is also a bigger plane than the 701!

Hi, Have you seen the price of the 914..? 915 Not released Yet and going to be real pricy?? Just talked to Rotax in Sebring today around $35-$40 Thousand US $$ Both are turbocharged and over rated?.I don't like pushing and to complicated.

I think the new Rotax 915 will be a great engine for the 750, it should give improved takeoff and cruise performance but it is very very expensive.

I'm with Wayne on the complexity of the turboed motors and sure wouldn't pay the price. The 912ULS was too expensive too and more complicated than I like but it was the obvious only choice for maximum STOL performance. There's just not anything else out there that I'm aware of that will match it and most other motors fall way short of the Rotax. I wonder about the little turboprop (I forget his name) is running and how it does. That is a cool plane!

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