R

Righty

Active Member
The other thread about the O-235 got me thinking about lightweight engines and I came across some posts about the IO-233. I can't find any recent news on this engine, but it sounds like it might be a good match for the 9. While I like the O-235, I also like the idea of a 'single-lever' engine, no carb heat or mixture to fiddle with.

So, anyone heard any news on the 233 lately? It seems this was still a paper engine as of summer '08. Maybe it will be ready in 5 years when I'm ready for an engine?

There was also reference to Thunderbolt O-235 engines from Lycoming in the other thread. It appears that these can be delivered with Aiflow Performance (fuel injection?), and one could install an E-mag as well. Is there any fundamental difference between this setup and the proposed IO-233?
 
On the 16th a sales rep from Lycoming is going to visit our EAA chapter and I asked him to speak to us regarding the 233. I'll report back.

BTW, based on what I saw at OSH this past summer, the 233 will only be available with a E-mag Air ignition. It was significantly different than the E/P-mags but at this point I know no details.

I THINK it will still have a mixture control but in place of a carb I THINK it will have a throttle body fuel injection system,
 
Geico266 said:
I thought the ignition are going to be E & P-mags. :confused:
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It will be an ignition by Emag Air but not the E/P-mags as we know them.

The ignition on display at OSH was a very unique design but it did have the Emag Air Logo on it.

Lycoming did everthing they could think of to reduce the weight of the O-235, inlcuding changing the accessory case, thus the new ignition.

Here is a note I posted on a prior O-233 thread:
N941WR said:
And here is a picture from the E-mag Air web site of the engine.

I like that they are going to certify it for both 100 LL and auto fuel.
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Remember, that is an early prototype ignition and is subject to change.
 
Something to think about.............is performance with density altitude. The RV generally has a safety advantage over the spam can's because of it's ability to climb two to three times the rate of an average Cessna or Piper.

By throwing on the smallest displacement engine possible, you've diminished that safety margin. If the pilot is to putter around at sea-level areas all the time, then that's okay, I suppose. If the intention is to get into any mountainous areas or high altitude airports; then go with a bigger engine.

As I live and fly in a higher altitude mountainous area, I've known far too many pilots and aircraft who have unfortunately bit the dust because of density altitude and lack of performance when they needed it.

L.Adamson ---- RV6A/ Lyc 0360/ Hartzell CS
 
It's all about the mission

L. Adamson,

I agree that one must think about DA. This is a life-safety-critical item that one must consider in their pre-flight planning. Every airplane will have its limits regardless of hp. The key is to know those limits and abide by them for the given aircraft in the given situation. Thus, I don't feel that using a level of hp that is within the original design specifications for the airplane diminishes any safety factor, rather it gives the airplane a different mission than one that uses maximal hp.

If you go by Van's numbers, the 9A still climbs at 950 fpm at gross weight on 118 hp compared to the 670 fpm that the C-150's that I'm used to are rated for. This is still a 42% improvement and is plenty of performance for this low-time, mostly low-land pilot.

I'm still considering going with the maximum power rating of 160 hp and a CS to achieve max performance with the airframe. I can see the value in this configuration. However, the mission for my airplane is in part to do more with less, light and simple. This is still accomplished at minimal hp with the 9. I see this as part of the beauty of this design.
 
Looks like a good engine, but IIRC, the Lyc O-235 is 118Hp where the O-233 is 100 Hp. Almost 20%. For an aircraft like the -9, which can weigh up to 1800 lb, you're going to have poor hot/high performance with the O-233. Might not be as bad if you had a CS prop, so you could get all the RPM out of the engine during climb. Still, 1800 lb and 100Hp makes for (duh) 18 lb/hr ... not exactly spritely performance. Going to a 118 Hp engine makes it 15.25 lb/Hp, much better. Of course, that's at 2800 RPM, and unless you have a CS prop, you're not going to get that out of the engine in climb.

One note: Lyc has stated that the O-233 can be rated at 100 Hp MCP @ 2400 RPM or 118 Hp MCP @ 2800 RPM. I suspect this is the same trick as derating the O-360 to 160Hp in the C172R. Not sure if any internals would have to be changed to get the 118 Hp rating, probably not.

And if not, this begs the question: Will the O-233 replace the O-235?

TODR
 
Just curious - someone brought up the Gemini engine in another thread, and I have heard rumors that DAIR (I think that was the orignial group - the photos look the same) has already started shipping the 100hp version. If this is true, then they might also be shipping the 125 hp version (same engine with a blower) - that might be a perfect fit for this aircraft.

Gemini Engines - predicted lineup

Most people seem to agree that 100hp is simply "on the weak side" - it is a shame they stopped producing the O-290.
 
Righty said:
If you go by Van's numbers, the 9A still climbs at 950 fpm at gross weight on 118 hp compared to the 670 fpm that the C-150's that I'm used to are rated for. This is still a 42% improvement and is plenty of performance for this low-time, mostly low-land pilot.

...the mission for my airplane is in part to do more with less, light and simple. This is still accomplished at minimal hp with the 9. I see this as part of the beauty of this design.
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Aaron,
I also see the beauty of "less is more" designs and have long admired the RV-9(A) in this regard. I have too many projects already in my queue but an RV-9 (yes, the taildragger, it's even lighter and simpler) with an O-235 has long been an idea floating around in my head.

If you you are committed to the mission profile stated above then I encourage you to stay the course. Of course your investment will be lower as well.

My main reason for writing though is to make sure you're aware of the article Van wrote in the RVator years ago just after the -9A was introduced. It compares the -9A to a C152. IIRC both he and brother Jerry flew both back to back and it was an enlightening comparision.
 
TODR mentioned that the 9 can weigh as much as 1800 lbs. True, but the gross weight for a 9 with an O-235/IO-233 would need to be set at something more like 1650-1700 lbs. This should be doable given that I plan a minimalistic interior and instruments, tip-up, fixed pitch, and light engine.

With the IO-233 being 50 lbs lighter than the O-235, I'm wondering how this would affect weight and balance. There was discussion in this thread...

http://www.vansairforce.com/community/showthread.php?t=36806&highlight=building+light

...about how losing weight in the front negatively impacts the baggage capacity. Anyone have insight as to whether this would actually be a concern with the 9A?

If the W&B issues could be sorted out, the empty weight might be in the neighborhood of 965 lbs. At this emply weight, you could fill the airplane with two 200 lb people, full fuel, and 75 lbs of baggage and still have a total weight of 1656 lbs! If aft cg is a problem, would it be possible to mitigate this without adding total weight? Things like a longer engine mount and moving optional location items up front come to mind. From what I've seen of other non-standard installations, this could quickly get very complicated, moving me back to the 235 route.

I wonder if this is on Van's radar. Lycoming says that they are working with OEMs concerning this engine. Would this include Van's? Will they develop a FWF package for this engine if it becomes the successor of the 235?
 
breister said:
Just curious - someone brought up the Gemini engine in another thread...
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This engine is also on my radar. I am intrgued by some of the new diesel designs. These are very promising, but the lack track record and market share make me nervous. I also don't like the prospect of having to develop the FWF installation, which is why there is a strong chance that the IO-233 will not make the cut for me if the W&B is a real issue as discussed earlier.
 
randylervold said:
...My main reason for writing though is to make sure you're aware of the article Van wrote in the RVator years ago just after the -9A was introduced...
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Randy,

I would be interested to get a look at this article. Do you know where I can find it?

Thanks.
 
Righty said:
...With the IO-233 being 50 lbs lighter than the O-235, I'm wondering how this would affect weight and balance. There was discussion in this thread...

If the W&B issues could be sorted out, the empty weight might be in the neighborhood of 965 lbs. At this emply weight, you could fill the airplane with two 200 lb people, full fuel, and 75 lbs of baggage and still have a total weight of 1656 lbs!...
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More like 925 lbs empty weight. Figuring my O-290-D2 is 264 lbs and my plane was 990 lbs. Take off that extra 64 lbs and you get some low weight. BTW, last night a sales rep from Lycoming spoke at our EAA chapter member and they now think the 233 will come it less than 200 lbs.

You might have to add some weight up front for the CG to work but you can play with my numbers on Dan's W&B page to get an idea of what to expect.

I've posted this before... There is a local -9A with a 108 HP version of the O-235 and the builder / owner flight plans it for 150 MPH and goes non-stop from OKC to Hickory, NC.
 
N941WR said:
...You might have to add some weight up front for the CG to work but you can play with my numbers on Dan's W&B page to get an idea of what to expect...
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Bill,

I took a look at the W&B, but I'm just guessing without knowing the moment arm for the engine. There's also the difference that I'm building a 'A' model, so there will be less wheel weight in the back and more in the front, which should help, especially given the verly long arm of the tail wheel.

I'm guessing that the engine moment arm is about halfway between the datum and the wing leading edge (say 34.3 inches aft of the datum). Given this assumption, one would definately need to pay attention to aft cg with a 200 lb engine. Although it appears that moving the wheel up front and adding a modest amount of ballast could make it doable. Maybe a three-blade prop would also help a bit.
 
CG

I know that Van's extended the 9's engine mount 2" for the 0-235 vs the 0-320 application due to the engine weight difference to aid in achieving the C/G easily. I wonder if Van's plans on doing the same for the weight difference between the 0-235 and the 233?
Mike H 9A/8A
 
mike109g6 said:
I know that Van's extended the 9's engine mount 2" for the 0-235 vs the 0-320 application due to the engine weight difference to aid in achieving the C/G easily. I wonder if Van's plans on doing the same for the weight difference between the 0-235 and the 233?
Mike H 9A/8A
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FYI - My plane has the longer engine mount and cowling. I would doubt Van's will build 3rd mount and cowling for the few people who use this new engine.

Putting a metal prop up front (40 vs 9 lbs) and using a heavy weight starter will shift the CG a good bit.

Just remember, with the O-235 the GW is supposed to be 1600 lbs. That is based on ROC, as I understand it. Still, setting the GW at 1750 should only reduce your ROC by 450 FPM +/-, putting it in line with a Cessna.

That is a very reasonable GW, when you figure out what your useful load will be.

One thing that I truly believe helps my performance is the duel electronic ignition (P-mags). I have read that one EI increase HP ~ 5% and two increase it by ~ 7%.
 
N941WR said:
...Putting a metal prop up front (40 vs 9 lbs) and using a heavy weight starter will shift the CG a good bit.

Just remember, with the O-235 the GW is supposed to be 1600 lbs. That is based on ROC, as I understand it. Still, setting the GW at 1750...
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Good point Bill. Adding a 40 lb prop up front appears to resolve all of the aft CG issues, allowing you to load it in any possible manner that stays below the GW. I tried every way and I couldn't get it out of limits. The CG still tends to stay towards the back of the range, which should be good for that nose wheel.

Incidentally, the empty weight would still be South of 1000 lbs. Useful load would be something like 770 lbs with a GW of 1750. Thats two 240 lb people, full fuel, and 75 lbs of bags! I don't know If I would take it that far. Something like 1650 would seem to be a good compromise. That limits the people weight to about 380 lbs total (with full bags and fuel).
 
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Righty said:
Good point Bill. Adding a 40 lb prop up front appears to resolve all of the aft CG issues, allowing you to load it in any possible manner that stays below the GW. I tried every way and I couldn't get it out of limits. The CG still tends to stay towards the back of the range, which should be good for that nose wheel.

Incidentally, the empty weight would still be South of 1000 lbs. Useful load would be something like 770 lbs with a GW of 1750. Thats two 240 lb people, full fuel, and 75 lbs of bags! I don't know If I would take it that far. Something like 1650 would seem to be a good compromise. That limits the people weight to about 380 lbs total (with full bags and fuel).
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Aaron,

On the way to OSH last year we ran in to one minor problem. Two of us at 220 each + 90 lbs of "stuff" left us no room for our beer cooler. :(
 
Is there a metal FP prop for the O-235?

N941WR said:
....
Putting a metal prop up front (40 vs 9 lbs) and using a heavy weight starter will shift the CG a good bit.
...
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Now that I think about it, is there actually a metal FP prop that is optimized for this size engine with the 9? I don't see any Sensenich FP props designed for the 235 on Van's website.
 
Righty said:
Now that I think about it, is there actually a metal FP prop that is optimized for this size engine with the 9? I don't see any Sensenich FP props designed for the 235 on Van's website.
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I think there might but but check with Van's and Sensenich. Van's for the proper size and then Sensenich so they can make one for you.
 
better than a Tomahawk?

Well, since Bill is still waiting for boxes, I might as well throw out this theory; Even if you set the GW at 1750 for the 9 with a IO-233 shouldn't the RV outperform a Tomahawk at 1670# in every way even at a slightly higher GW of 1750? Stall speed is slower on the 9 by 5 knots or so and the lower drag at climb speed should offset the slightly higher weight, no? Takeoff thrust with the prop extension should also be slightly greater with the right prop.

So if GW is limited by ROC, and the 9 can outclimb a Tomahawk both by rate and much better by angle, then why wouldn't such a 9 be perfectly as airworthy as a Tomahawk.

Yes, I know that is setting the bar quite low for an RV, but this is all theoretical at the certificated GW of 1750. Even with four buttocks, fuel and some bags, the 9 with the IO-233 would be much lighter than those with bigger engines and at least 100 punds uner a Tomahawk, so the real-world performance would be pretty decent I hypothesize. Well, from Vans numbers on the prototype, this is not really very speculative.

It wouldn't be the hottest 9 ever, but it might be the fastest on 5 gallons per hour ever.

As to CG, just use a light, swivelling, tailwheel, no tailwheel steering, no lights in tail, maybe lose some tip fairings on the elevators, rudder etc. Smaller engine means less need to maximize rudder area, so any slight, likely tiny, reduction in control authority would be mitigated by less power.

This is all hangar talk, of course. The simple truth is that I will likely go with the IO-320 like lots of other folks. Not that _plenty_ of power is a bad thing, but I just wish something closer to the O-290 but with FI were easier to do. I realize it can be done, but for the reasons Bill has outlined it's not so attractive.

What do you think?
 
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