Essentially it works out at 162 hp per rotor at max power, and 125 hp per rotor in cruise - going with the all aluminium engine will help with the cooling, down here we have a company called PWR who make some really excellent cooling products including a water cooled oil cooler that I think are going to help with the cooling quite a bit.RSD,
Thanks for the update/reply; good to see you're somewhat more realistic in expectations, including choice of redrive at that HP level. And four rotors should make any TV issues easier to deal with. Given the somewhat limited details in the original post, I was fearful that you might be like some of the folks that participate on what I'd call the 'other' rotary a/c forum here in the USA. I've seen guys expecting to fly a 2 rotor 13B making that kind of HP (in some cases, on something like a Van's RV-x). Really scary to think about trying to do that. Even with 4 rotors, that's a lot of HP per rotor, with the understanding that you'll need at least 75% of that, continuously. I wonder if cooling might be a bigger hill to climb than the mechanical issues.
That's pretty much why the project suddenly went in the Allison direction - at the direction of the German Air Force - they didn't want the logistics of dealing with a different fuel.On the NSU vs Allison issue, my bet is that there was never a chance that any well funded military would have ever bought the a/c with anything other than a turbine in it. Here in the USA, even Beech T-34s, that originally flew with avgas piston engines, got turbines decades ago in the military. It's just too painful to support two fuels, plus they have a real aversion to gasoline due to its higher volatility.
Will do.Good luck with the project, and please keep us updated on your progress. (And thanks for not taking offense; I was just concerned for safety reasons.)
If I spin the fan faster than 3800 rpm the noise will get brain shattering due to the tip speed. 3800 rpm on a 37.5 inch fan is 0.7 mach - over that and the noise levels get deafening650 HP @ 3800 is 900 pound feet torque.
Even a 500 inch LS will need a BMEP of 271 PSI to get there. That's not happening as a NA configuration.
Since the plan is to turbo it anyway the DD LS is worth at least a trade study look.
Back off on the 650 HP requirement or spin the fan a bit faster and things get easier on the engine side
That sounds about right - a tip speed of 800 fps seems to be the best compromise between thrust and noise.I found the Q-Fan paper. The Q stands for "Quiet" so they were after 18dba quieter than GA aircraft (with high tip speed props). They proposed 3' feet diameter, 387hp reciprocating or rotary, 640fps tip speed/4060rpm.
But 4500rpm and 750-800fps or more is optimal if not concerned with extreme quiet.
Tracy Crook's "Aviator's Guide to Mazda Rotary Conversion" and "The Mazda Papers" just landed in my mailboxThanks for the update/reply; good to see you're somewhat more realistic in expectations, including choice of redrive at that HP level. And four rotors should make any TV issues easier to deal with. Given the somewhat limited details in the original post, I was fearful that you might be like some of the folks that participate on what I'd call the 'other' rotary a/c forum here in the USA. I've seen guys expecting to fly a 2 rotor 13B making that kind of HP (in some cases, on something like a Van's RV-x). Really scary to think about trying to do that. Even with 4 rotors, that's a lot of HP per rotor, with the understanding that you'll need at least 75% of that, continuously. I wonder if cooling might be a bigger hill to climb than the mechanical issues.
It seems to me that the OP is also intending to push to high power and rpm levels relative to present experience.I've read a lot about Powersport's issues, as well. But I've also read that they were pushing everything to the limit, including hanging heavy metal props on them, running nitrous, etc. It might be worth pointing out that they were hard core hot-rodders at heart. When you push the limits, you're likely to break stuff.
Ev Hatch was experienced at building and maintaining many engines of many types in hydroplanes and race cars. He built race engines that both ran all season and won races, then freshened them up over the winter. His rotary powerplant for airplanes came along only after building durable race engines based on various go-fast parts for Mazda's. He was also a champion road racer in Camaro's. He knew his way around making power and not breaking.Any chance that PS & the other the guys that had serious issues with the rotary, had been getting help from 4-per-rev, and the relative wet noodle of a crank when playing with V-8s, & got no help from the E-shaft when they switched to the rotary?
As I said above, I am sure that the existing planetary drives work fine with normally aspirated 13B's. The OP is going WAY beyond that level of power both per rotor and for the whole engine as well as up-scale on rev's too. I think that the experience of folks who both had trouble and solved those troubles would serve as a marker for the potential issues he might see. I thought he should be so warned that it might become a challenge...Weigh the PS experiences against the dozens (hundreds?) of RWS & modified Ross drives that are flying successfully with hundreds to over a thousand of hours on them. There is absolutely nothing 'special' about the RWS damper/coupler. (It doesn't even exist in the most recent version of the drive.) If the problem is the engine, then the same problems should show up in other iterations that have the same configuration and in some cases, the same gearsets. Even the old Ross drives (made by Ross Sr.) seem to have held up just fine except for the fact that Ross failed to include a thrust bearing on the drive's input shaft, and the sun gear/input shaft would axially load the E-shaft, and destroy the rotary's internal thrust bearing in short order.
Billski,As I said above, I am sure that the existing planetary drives work fine with normally aspirated 13B's. The OP is going WAY beyond that level of power both per rotor and for the whole engine as well as up-scale on rev's too. I think that the experience of folks who both had trouble and solved those troubles would serve as a marker for the potential issues he might see. I thought he should be so warned that it might become a challenge...
I wish that I had been able to know Ev Hatch better. I did not agree with his design path, but it is hard to argue with success, and his scheme did work.When I mentioned that the latest version of the RWS reduction didn't use a soft coupler, I didn't mean to imply that it became a stiff system; it's not. It does have a somewhat higher mass flywheel, but it still behaves as a 'soft' system, with resonance below idle. Lash in the planetary handles keeping resonance below idle. The 2.85-1 ratio drives, with 6 planetaries, have been run successfully on both supercharged (on an RV-10) and turbo'd 2 rotors (on an RV-6), and on at least one P-ported 20B 3 rotor on a Lancair ES (obviously should help a bit with TV issues). An electric MT 3 blade prop (around 30 lbs) on both the Lancair and the RV-10. The Lancair guy found some creative ways to break stuff, but the planetary gearset itself never gave any issues.
RSD and traded notes on this privately. I will share my responses as they may help the larger community understand the topic. Yes, I edited it a bit for clarityIn one of the earlier posts someone mentioned that a four rotor engine would create less problems than a two rotor engine - is that your view too? At the moment I'm waiting for measurements for a six rotor engine to see if we can fit that in which might mean the engine stays normally aspirated.
Another question - this is a drawing of the original arrangement in the Fantrainer, do your think it best to connect the engine output shaft to the flexible coupling that is closest to the fan or directly connect it to the fan?
Check out the surplus turbine dealers out in the world, had a movie production Co. buy a ducted fan ground unit [Boeing T 50] why go piston with its power pulse issues most are about $20,000 price range (airliner APUs & GPUs)OK cheers for that. Some interesting reading for me to do there. I'm fortunate in my case that all of the hard work for the duct/fan design is done, I've acquired an airframe with all that installed and working, but without the very expensive 650 hp Allison turbine. Not having a spare $300,000 or so available I'm looking to drop a 650 hp rotary in there with the aim of making it go like this again -
I think that bit got lost in translation somewhere - what actually happened was that Audi (which owned NSU - the makers of the Wankel engines) made a decision to stop manufactuing the Wankel motors so supply became a problem, and at the same time the Luftwaffe (who were funding the development) requested that they switch to Allison turbines as they had an oversupply of them and they didn't want the logistical hassle of needing mogas as well as avgas.
Going direct drive would require a rework of the fan hub assembly as the PRSU is built into it and I don't want to go there as that is just more work, and I'm not sure that a turbo rotary would produce enough power at those sort of much lower revs - I don't have the knowledge of rotaries to knowIf the power limit per rotor is a thermal one, coud it be turbo'ed to run direct drive rpms? That would also help with the godawful noise of a NA engine.