I just got home from OSH, spent several hours at the DeltaHawk booth and enjoyed meeting Craig and several of the DH guys. Was going to post some pics but I think Craig already has that covered above. I asked a ton of questions and thought I'd share what I learned for those interested. Disclaimer: I may not have heard everything correctly so no guarantees about the accuracy of this info, and of course it's all subject to change...
The prototype installation on Craig's -14 has a PlanePower alternator and SkyTec starter, but DH has responded to feedback and the production engines will come standard with B&C alternator and starter which is great to hear.
There is ongoing discussion about how far aft the engine can be moved in the RV-14(A) installations, and part of that decision is how much space should be provisioned for the accessory drive pad. From previous history of discussions about the IO-390 I think many (most?) builders have been putting on a backup alternator. A B&C backup is quite a bit larger than the compact MonkWorkz unit...I think the latter would be sufficient for most people and would allow the engine to be moved back a bit (with CG and aesthetic benefits).
I asked whether there was any risk of hydraulic lock given the inverted Vee orientation and was told they did extensive certification testing to prove to the FAA that it isn't an issue.
The Idle Governor is actuated by a solenoid in the fuel control unit. I was told it does not have a failure mode which would lead to engine power loss.
Engine warm up time in summer is typically 5-7 mins before coolant temp reaches the minimum for takeoff power. In winter it will be longer although the Tanis preheater system (which will be included) will help by ensuring the main engine block is already warm.
I inquired about how they avoid excessive piston ring wear around the intake/exhaust ports (keep in mind this is a 2-stroke...no intake/exhaust valves). There are three rings on each piston, the lowest one is an oil control ring that never reaches the ports at TDC. The two upper rings, which do pass thru the region where the ports are located, are pinned to ensure the rings never rotate. This keeps the split in the rings aligned with the portion of the cylinder wall between the intake and exhaust port (otherwise the ends of the rings could catch on the edges of the ports). The ports are chamfered and extensive testing has shown no significant wear on the rings around the edges of the ports.
I asked why the decision to both supercharge and turbocharge the engine. Answer is that the supercharger is important at low RPMs and turbocharger is better at high power settings and also at high altitude. Plus they provide some redundancy as the engine can still run (at reduced power output) on only the supercharger or the turbocharger if one or the other fails.
The supercharger is a twin screw type. One of the screws is driven directly by the serpentine belt. The other screw is driven by a gear from the first screw, and the pair of gears are in their own self-contained gearbox with dedicated gear oil.
The oil pump has three impellers ganged together inside one housing. Two of them are scavenge pumps and the other is the pressure pump.
The mechanical fuel injection, oil pump, turbo- and supercharger are all unique to DH, that is none of them are off-the-shelf from other engines...DH started out earlier in development working with proven components & engineering expertise from other suppliers but the designs have evolved into their own custom solution for the DH engines.
The RV-14 installation brings the exhaust pipe out thru the tunnel area. Exhaust pipe routing on the -14A is still TBD. The DH guy I talked to was thinking about splitting the pipe (after the turbo) to go around the nose gear and then rejoining it in the tunnel. I suggested that it may be simpler/better to use exhaust exit(s) that are NOT in the tunnel similar to what Van's did when they reworked the FWF installation for the IO-390-EXP119...that configuration should work for both the -14 and -14A models, keeping the cowling identical. The tunnel could then retain the stock Van's cover & cowl flap to minimize drag.
The prototype cowl for the -14 has access panels for checking oil, coolant, and oil drain. There is no provision for a cowl flap, that will be evaluated based on flight test data once Craig has the -14 flying.
None of the currently planned DH installations have provision for a muffler, although they acknowledged they'll eventually need to address this for some customers, especially those in Europe. I'm not sure it would be possible to fit a muffler in the RV-14 cowl but would be interested if one was available.
Craig's RV-14 is using a duplex Andair fuel selector. It looked like 3/8" fuel lines for both the supply and return, so when you're building the fwd fuselage you might want to plan accordingly.
The electric boost pump is something DH is still sorting out. The initial plan for the -14 will have it mounted on the hot side of the firewall...I didn't catch the specs, but apparently the boost pump requirements for this engine exceed the capabilities of the typical AFP or Andair boost pumps used in IO-390 installations. I also heard a comment that DH wasn't sure they would keep the boost pump in the long run.
I asked how many hours DH has put on development engines in the test cell...answer was something like ten engines that each have ~5000 hours on them, and most of those hours are running them hard (abusing them). Long term they expect 3000 hr TBO and eventual goal is 'on condition' with no TBO at all. Cylinders have a steel sleeve that can be replaced and of course bearings, pistons/rings, and all of the accessories (fuel control unit, water pump, oil pump, etc) can all be replaced. DH stressed that they do not plan to have a life limit where you essentially throw away the engine and buy a new one.
The engine will still run with a cylinder inop (clogged injector for example). DH has demonstrated that it will run on only two cylinders albeit very rough and with significant power reduction. It will also run for a while after loss of water pump/coolant and they had to demonstrate this during certification testing, so if you have a coolant overtemp alert in flight you would have a decent chance of getting it on the ground at the nearest airport without the engine seizing up.
I asked about oil consumption and was told it's nearly zero...much more like a modern car vs. a typical Lyc/Cont where you're adding a quart every dozen hours (with much of it ending up on the belly). Also asked about oil change interval and DH is still working on a recommended interval, the guy I asked thought they would try to start out around 150 hrs and maybe extend that eventually (start out conservative). Regardless it should be significantly less frequent than the air-cooled engines where we're accustomed to changing oil ever 25-50 hrs.
They will likely recommend a compression check & borescope check (both via the glow plug port) at every annual.
Other maintenance items like replacing the coolant and serpentine belt are also expected to be 'like your car'...very long intervals.
DH has tested engine shutdowns and restarts in flight, both with prop windmilling and after prop has completely stopped. It handles restarts well and there are no complications if you forget to switch tanks and run one dry (i.e. it gracefully handles purging air from the fuel lines in this scenario and restarts quickly).
DH hasn't tested the engine for acro yet and they are wanting to gather data from the RV-14. Structurally the engine mount is designed to handle the RV's ultimate G loads and the engine itself should handle the loads as well but DH was non-committal pending the additional test data. Note that Craig's -14 won't be equipped for inverted fuel/oil but there's nothing inherent about the engine design that would preclude such a setup if you provisioned for the pickups in the fuel & oil tanks.
Propellers: so far Hartzell has tested several instrumented carbon fiber props with the DH engine, the plan is to approve existing propellers and DH does not expect the engine to require a new custom prop design. DH is wanting to get other brands approved as well, especially since Hartzell acquired Whirlwind which removed their main competition with predictable results for the consumer...hopefully MT, Catto, etc will come to the rescue with some competitive alternatives. BTW there are no plans to approve an aluminum prop due to both weight and vibration concerns.
Speaking of props, I got mixed answers from different people at the DH tent about the anticipated RV-14 FWF package & price. One person told me they are targeting $110-120K including the prop, someone else said $110 not including the prop...and if the only option initially is a Hartzell carbon fiber prop, that's another $20-27k depending on the model. Hopefully they can figure out how to contain the cost of the whole package so they don't price themselves out of the Experimental aircraft market.
BTW I also stopped by Van's tent and spoke with Rian and Greg, both confirmed that they will allow the -14(A) finish kit to be customized for builders who want to remove the mount/cowl/etc for the IO-390 (you would get partial credit for the removed items per long-standing policy). Otherwise they aren't budging on customization for the emp/wing/fuse kits (per new policy established during Ch 11). Hopefully at some point Van's will support the DH option in the finish/FWF kits as it would probably be more cost effective than having to delete IO-390 components and then go to DH to get the full FWF package separately. Fingers crossed.
Lastly, Rian noted that DH didn't build any nose-right offset into the engine installation in the -14. This was discussed earlier in this thread, seems there was a disconnect between Van's and DH engineering on that one. So it will be interesting to see how much right rudder is needed to center the ball. I would imagine they will fix this along with other changes to the engine mount and cowl on the second -14 installation that Craig already has in the works.
