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Low end RV9-A and UL350IS power plant

N

NinerBikes

Well Known Member
Mention has been made that the RV-9-A was originally built with an O-233 O-235 based motor that was pulled from a Cesna 152, at around 118HP.

I am well aware that most build their RV-9 with an O-360 or perhaps an O-320, and you will come across builds with the O-233 or O-235 for sale every now and then.

My curiosity is about what kind of performance, hypothetically, that could be expected out of a RV-9A with a 130 HP fuel injected 4 cylinder engine with about 214 Cubic inches that will run on MoGas Premium, and estimated 75% power cruising speeds.

Thoughts?

http://ulpower.com/en/engines/ul350/ul350is
 
Vans list performance for 135HP as follows:
Top speed: 178MPH
75%: 173MPH
55% 156MPH
RoC: 1100/1400FPM, solo/gross

You might lose 20FPM and 1-2MPH with the 5HP you don't have. I can't recall what the ULPower engine is these days, but a derated O-340 weighs the same as an O-320 and can burn MoGas yet gives 165HP and will probably be very similar in price. And you won't have to worry about a custom FWF setup. I have one in my -9A and true out at 145KTAS burning 24.5LPH.
 
Van's numbers are to be believed!

My -9 Dragon Tail started life with an O-290d2 rated at 135 hp continuous.

I would typically cruise it at 65% power and see 145 knots / 165 mph.

The -9 wing is stunning!

One major advantage of the smaller engine is the low fuel burn really extends the range. Granted, you can always throttle back a big engine to get the lower speeds and fuel burn but you will struggle to build it light with a bigger engine.

If you are worried about resale, put an (I)O-320 up front!
 
The technical issues I see are:

Lighter weight engine (requires extended motor mount, possibly cowl, and if cowl is extended, *theoretical* destabilizing due to extended nose)

Slightly lower than expected climb rate due to the smaller diameter prop that will be required for the higher rpm engine (3300); shouldn't affect cruise
 
I was going to comment that plenty of people run mogas in their lycomings without issue, and I doubt any efficiency increases in a rotax would outweigh all the downsides. But you actually asked theoretically what performance to expect, not whether it was a good idea, so I would agree with bill that numbers would be close to the 135 hp numbers listed by vans, assuming you find a good prop.

Chris
 
You might want to think about your W&B, Without the nose weight your baggage might be limited. Especially if you have a light prop.

I will also attest to the other posters comment on significant additional work required the further you deviate from the standard. Even an IO320 in 9 causes a bunch of additional work with the engine Vans sells you(custom fuel lines, mixture cowl blister..). The Vans engines are also a heck of deal for a standard Lycoming.
 
YellowJacket RV9 said:
I was going to comment that plenty of people run mogas in their lycomings without issue, and I doubt any efficiency increases in a rotax would outweigh all the downsides. But you actually asked theoretically what performance to expect, not whether it was a good idea, so I would agree with bill that numbers would be close to the 135 hp numbers listed by vans, assuming you find a good prop.

Chris
Click to expand...

Chris, the UL-350 IS is not a Rotax. It's an experimental rated engine, direct drive, no gearbox up front Fuel Injected, mechanical fuel pump, dual ignition 4 cylinder motor, capable of 130HP at 3300 rpm.

Are RV-9As built with an O 233 or O 235 having weight and CG balance problems too?
 
NinerBikes said:
Chris, the UL-350 IS is not a Rotax. It's an experimental rated engine, direct drive, no gearbox up front Fuel Injected, mechanical fuel pump, dual ignition 4 cylinder motor, capable of 130HP at 3300 rpm.

Are RV-9As built with an O 233 or O 235 having weight and CG balance problems too?
Click to expand...

My apologies, I skimmed to quickly. I still think the basic premise is the same. There really is no way to beat the Lycoming in a lot of ways, if only because of how well established the package is. Designing and building a mount and fwf for a different engine just never seems to be worth the time and effort once everything is compared apples to apples. The price of the UL engine looks the same as what you could pick up a new lycoming for, but with less power. If running mogas is important, you can do that with a lycoming too. You can also do electronic injection and ignition if you choose. But, unless brave people try new things, the industry won’t advance. So more power to those of you experimenting!

Chris
 
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NinerBikes said:
...
Are RV-9As built with an O 233 or O 235 having weight and CG balance problems too?
Click to expand...
Not for the O-235 and the reason is that Van's makes a 2" longer engine mount to accommodate the lighter engines. (I had one for my O-290d2.)

The O-233 is much lighter and may be an issue, I really don't know.

Also, if you get an O-235, you can put high compression pistons in it and get them up to around 135 hp. Add dual electronic ignitions and you will have one very efficient aircraft!

BTW, search on the O-235 pistons, this is a certified change that can be applied to C152's.
 
RV9A with a YO-233-exp

I built a Lyc YO-233-exp powered RV9A. The empty weight ended up at 1005lbs with all fairings, seat cushions ready to fly. My normal solo takeoff weight is about 1450 with full fuel. Cruise is about 140 mph at 2500 rpm @ 5000 ft.

After my experience, I would not recommend a non standard engine ( not offered by Vans currently ). The additional time required to complete your plane will be approx 1 -2 years ( My Experience)

In building a Vans RV9A Kit I built the standard stock kit with no mods. All the weight saving items you can use are forward of the firewall. Hence, any lightness you add to the RV9A moves the CG aft.

The Lyc 233 is a lighter 235 engine by about 50 lbs. I spent several months trying to calculate the final CG of my build. I finally decided to move the engine forward about 1.75" further than the Vans 235 engine mount. It was not enough. That was all I could do with the stock Vans 235 cowling, I used all the back of the cowl that would normally be trimmed off. I still had an aft CG problem but solved it by adding heavier components forward of the firewall.

Issues you need to face, Control cables custom length, engine baffles custom build, air inlet filter box is custom, oil cooler location?, engine sensors to gauges custom, battery location( Near UL350 exhaust?)

Vendors you call will have no clue how to help. They refer you to the manufacture ( That would be YOU).

I am happy with my plane, it is what I wanted, but it was not an easy project. Go in with your eyes open.

Good luck!
 
Having never flown in one, and with a stall speed of 44mph, is the RV-9A similar to the RV-12, in that you really have to watch and set up your approach to land and watch your speed, because it's slippery and just doesn't want to come down?

Asking about with a 0-235 equipped RV-9A, does it bleed off energy and speed fairly quickly at idle and at flair on landing?
 
I have only flown my RV9A and none of the other Vans aircraft.

I owned a Cherokee 140 before the RV9A.

I find the RV9A to be : Easy to Fly, Difficult to control and very forgiving.

It is very slippery and a little in-attention and the speed can increase or decrease 10-20 mph. Come in over the threshold high or fast and you will use a lot of runway.

However, I do not find this to be too big of a problem.

Be serious about transition training, the issue for me was from a Cherokee (Dump Truck handling, but stable) and the RV9A light and very sensitive controls.

The RVs require constant attention , but that is the fun part and why people like them so much.
 
NinerBikes said:
Having never flown in one, and with a stall speed of 44mph, is the RV-9A similar to the RV-12, in that you really have to watch and set up your approach to land and watch your speed, because it's slippery and just doesn't want to come down?

Asking about with a 0-235 equipped RV-9A, does it bleed off energy and speed fairly quickly at idle and at flair on landing?
Click to expand...

A fixed pitch -9 flies similar to a -12, IMHO, just a little bit heavier.

Speed on final is critical, as mentioned above! It is easy to let the speed get too fast and like any light aircraft, it bleeds speed fast. I'm not adverse to kicking the rudder out, if fast or high on final.
 
whd721 said:
I built a Lyc YO-233-exp powered RV9A. The empty weight ended up at 1005lbs with all fairings, seat cushions ready to fly. My normal solo takeoff weight is about 1450 with full fuel. Cruise is about 140 mph at 2500 rpm @ 5000 ft.
Click to expand...
Wow, that's surprisingly high for the lighter engine. What kind of interior do you have?

My Solo TOW is 1320Lbs, which is me + full fuel. Performance there is an initial RoC around 1700-1800FPM - which, if you want to have fun and get some circuits in, you can average 3m20s a lap and start your crosswind turn before the end of the runway. :D

I built a bog-stock -9A, with a derated (7.5:1 compression/165HP) OX-340S, 2 PMags and a Sensenich GA prop, polished instead of painted, and my empty weight came in at 981.5Lbs, without the gear fairings. I am about 990Lbs now with them and the Coey's seat cushions.

My BEW numbers were:
Left main: 368.5
Right Main: 369.0
Nose gear: 244.0
TOTAL: 981.5 and a BEW CG of 76.57

Personally I fly AoA on approach, and can be down and stopped in well under 1000' with an approach speed around 55KIAS. Great fun when you cross the threshold 200+ AGL and touchdown 300m from the far end because that's where the bowser at is. :p
 
Problem solved

My friend, Ray Lawrence in Sandersville Ga has cowlings and motor mounts for the -12,-6, -7 and -8 RV's, and is the UL importer with a 200 hp 6 cylinder UL in his -4.

Call him at Kaolin Aviation 478 232 9560
 
KRviator said:
Wow, that's surprisingly high for the lighter engine. What kind of interior do you have?

My Solo TOW is 1320Lbs, which is me + full fuel. Performance there is an initial RoC around 1700-1800FPM - which, if you want to have fun and get some circuits in, you can average 3m20s a lap and start your crosswind turn before the end of the runway. :D

I built a bog-stock -9A, with a derated (7.5:1 compression/165HP) OX-340S, 2 PMags and a Sensenich GA prop, polished instead of painted, and my empty weight came in at 981.5Lbs, without the gear fairings. I am about 990Lbs now with them and the Coey's seat cushions.

My BEW numbers were:
Left main: 368.5
Right Main: 369.0
Nose gear: 244.0
TOTAL: 981.5 and a BEW CG of 76.57

Personally I fly AoA on approach, and can be down and stopped in well under 1000' with an approach speed around 55KIAS. Great fun when you cross the threshold 200+ AGL and touchdown 300m from the far end because that's where the bowser at is. :p
Click to expand...
Those are great numbers! My -9 was exactly 990 pounds for its first flight with the O-290d2 with all the fairings and seats in it.

While I still don't fly AoA, when light I will approach at 55 knots and you are spot on, if I three point it, I can easily turnoff in 1000 feet.

In fact, I stunned a local controller when I landed, stopped, and took off again 200 feet before the start of fixed distance markers at a local airport. The fixed distance markers start a 1000 feet from the end of the runway. He mentioned that he had never seen anyone do that before, so I did it again, just to put an Exclamation point on the RV's performance.
 
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