What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

RV-12 Turbo?

S

spriteah

Active Member
I've just been pondering what if the 914 Turbo went into an RV12? With Variable prop? Anyone got any thoughts? I think Americans cannot do it but Australians can. I wonder what speed and performance improvement it would provide.

Any comments welcomed.

Jim.
 
Can't say particularly...

about the question, but as a turbocharging reference, I'd strongly recommend, Corky Bell's, "Maximum Boost". He explains turbocharging in a way that the layman can understand. He consulted on an automotive turbo project I am involved in and being able to reference his book kept me in it and well informed.
 
spriteah said:
I've just been pondering what if the 914 Turbo went into an RV12? With Variable prop? Anyone got any thoughts? I think Americans cannot do it but Australians can. I wonder what speed and performance improvement it would provide.

Any comments welcomed.

Jim.
Click to expand...
The 914 is 115 Hpand can be ordered ready for a CS prop. It does not have FI and is a bit pricy. Power isn't that much higher at (IIRC) 115Hp, but it will keep that power to high altitudes. So, your IAS won't be that much higher, but TAS will go up with altitude.

Best to check with Van's to see if the Vne limit is based on IAS or TAS (i.e., aerodynamic or flutter based).

TODR
 
Hot!

Vans appears to be already struggling with overheating of the 912S. A 914 is likely to make the problems so much worse, I'd have thought.
 
Something else to keep in mind about the 914: 1) It's just about $10,00 more than the 912. and 2) It needs the use of the constant speed prop to gain the extra 15HP and the use of a constant speed prop takes the airplane out of the LSA category. Steve
 
Thanks for the comments.

In Australia we are allowed CS props have no maximun speed and can have retractable gear.

If the motor is 10K more then that will mean I would not even consider it!!! I'll be struggling to get the 12 in the air as it is!

In Australia we are also limited to 5000 ft asl. So if the majority of the performance is gained at height then again it is no use to me.

Cheers,

Jim.
 
912Turbo

Jim, I agree that you would not gain anything by upgrading.The point we in Australia will have to contend with is the way the Radiator is placed as i can see problems with overheating where its placed now. Regards Brian.
 
Jim,

The Rotax 914, which is the turbo version is 115hp for take off, 5 minutes, and from memory 95hp continuous. The extra kick will be in the take off mostly I would think. Might be useful in the Aussie heat, I don't know. A good comparison would the the Europa, which are commonly fitted with the 914 AND the 912S, giving you a good comparison.

Remember the 914 is a turboed 912, the 1200cc engine and normally turns up over 2500rpm prop speed at rated power, where as the 912S is the 1350cc engine and turns up less than 2400rpm prop speed at rated power. I'd go for the 912S for more cubes and less rpm, but each to his own.

Another aircraft using the 914 is the Searey amphibian; check those out, they need the extra horses to get them out of the water.

A guy here in NZ transformed the takeoff performance of his 912 powered Europa by fitting a constant speed or variable pitch prop. Similar story for a 912 powered Pulsar. Our rules don't allow 1320 lbs but like yours allow constant speed props and retractable gear.

I doubt the 914 would be USD10K extra, but I don't have any quotes.

Remember the 914 is also quite a bit heavier, so Vans no doubt would frown upon the idea.

Cheers,
Andrew.
 
spriteah said:
I've just been pondering what if the 914 Turbo went into an RV12? With Variable prop? Anyone got any thoughts? I think Americans cannot do it but Australians can. I wonder what speed and performance improvement it would provide.

Any comments welcomed.

Jim.
Click to expand...

Hi Jim,

I am writing from South Africa, and our Sport Pilot/plane rules are also not as firm as the USA guys. :D

The 914 is much more expensive, and it will only help you during take-off and if you fly high altitudes. I am up in Johannesburg at 5500 ft ASL. Heat, weight and additional engine fitting complexities are going to be your enemy. Not unsurmountable but still you will have to experiment...

I am planning to fitting a std 912S keeping it easy to fit just as vans, but with a cockpit adjustable Variable pitch prop, that will give me the extra bite during take off from 5500ft ASL and extra pitch during cruise at altitudes 8000+ ft. The only change that will be required is that you have to move the pitot away from the spinner, since most VP Rotax Props adjust through the gearbox hole where Vans currently has the pitot sticking through.

Regards
Rudi
 
RudiGreyling said:
I am planning to fitting a std 912S keeping it easy to fit just as vans, but with a cockpit adjustable Variable pitch prop, that will give me the extra bite during take off from 5500ft ASL and extra pitch during cruise at altitudes 8000+ ft.
Click to expand...
Good plan. Our setup on the 912S only develops ~4800, maybe 5000 in climb. Being able to pitch the prop for 5300 to 5500 would help the TO and climb performance a lot.

TODR
 
Not only is the 914 heavier, wouldn't it be a cg problem for the rv12? you already sit in front of the spar as is. I do know that Rans has recommended to more than one person that it would fit nicely on the s19 but that's a pretty heavy plane already.

pete
 
gblwy said:
Vans appears to be already struggling with overheating of the 912S. A 914 is likely to make the problems so much worse, I'd have thought.
Click to expand...

Do you know if he is using the Waterless Coolant ?

If so, trust me he has to use the 50-50 Water Glycol based Coolant; To comply with the EASA coolant AD I did a lot of cooling testing on other installations to switch back to the 50-50 from the Waterless and install the higher pressure rad cap; That latter coolant will move your Coolant and CHT temperatures up by at least 40 F on the same installation...Not Good at all; OK, it may fix the false problem (not a problem if the installation is properly designed) of local boiling but shifts the problem to lower engine life and in a few cases I have seen, engine seizure ! Another thing with the Waterless Coolant, your Oil Temperatures will very likely exceed the limits, they are already high anyway. The 50-50 will keep them about 20 F lower than with the Waterless Coolant.

You will need a coolant gauge with a red line at 120 C (248 F), but trust me it will pat off; ROTAX was also working on a higher capacity Rad within the same original Rad dimensions; I tried it with some improvements but by far the 50-50 Glycol is the winner (about 8 times the delta Temp).
 
JetA4GA said:
Do you know if he is using the Waterless Coolant ?

If so, trust me he has to use the 50-50 Water Glycol based Coolant; To comply with the EASA coolant AD I did a lot of cooling testing on other installations to switch back to the 50-50 from the Waterless and install the higher pressure rad cap; That latter coolant will move your Coolant and CHT temperatures up by at least 40 F on the same installation...Not Good at all; OK, it may fix the false problem (not a problem if the installation is properly designed) of local boiling but shifts the problem to lower engine life and in a few cases I have seen, engine seizure ! Another thing with the Waterless Coolant, your Oil Temperatures will very likely exceed the limits, they are already high anyway. The 50-50 will keep them about 20 F lower than with the Waterless Coolant.

You will need a coolant gauge with a red line at 120 C (248 F), but trust me it will pat off; ROTAX was also working on a higher capacity Rad within the same original Rad dimensions; I tried it with some improvements but by far the 50-50 Glycol is the winner (about 8 times the delta Temp).
Click to expand...

I've come to the same conclusions on the Subaru. The Evans NPG+ caused much higher coolant temps in back to back testing to EGW. I've settled on 70% distilled water, 30% EG and a dose of Redline Water Wetter to reduce surface tension. This is noticeably better than 50/50 EGW but may not be suitable for very cold climates. Rolls Royce came to similar conclusions back in 1943 where they had been using pure EG initially and switched some engines to 30/70 EGW. This allowed increases in hp and higher ratings at altitude without going to larger rads on some aircraft such as the Hurricane.

Despite the sales hype and the supposed advantages of Evans, actual instrumented testing confirms what the specs already say- it has considerably worse heat transfer rates than traditional coolants. BTW the specific heat for 100% PG is .600, pure water .998, 50/50 EGW about .790, 70/30 EGW .885. The thermal conductivity of 50/50 EGW is about 40% lower than that of pure water.
 
Last edited:
No controls on the V-prop.

In the US, it's not "constant speed" that's not allowed for light-sport. It's "cockpit adjustable".
Click to expand...

The V-prop self adjusts, no interferance from the pilot. The little propeller on the spinner will adjust the prop for best efficiency, no matter what the airspeed is. Also the little propeller supplies the power for the electric motor inside the spinner, so there is no external electrical power supply or hydraulics to run it.

Regards, Tonny.
 
You must log in or register to reply here.
Back
Top