cooling system and upgrades

[Sam Oliver]

I am going to have to school myself up on this cooling issue and different ways to mitigate it.   It will be quite awhile until I get to that point in my build but since I live in Central Texas, it's going to be an issue I'm sure.   I'll be keeping an eye on whatever you end up doing with the Phoenix kit you are going to build up.   So please keep the ideas and solutions you come up with coming.   It's a big help for us who are not engineers.
Sam

[Tim Morris]

Sam, I have been trying to find a solution to my cooling as well without major modification.  I live in South Central Texas.  I like Graeme's solution, but that is last resort since my ship is already flying.  I get 10–15 minutes of hover training completed with my bride before I am at redline.  So far, the best solution has been to remove the rear cowls when I am doing hover training.  This tells me it is an airflow problem.

I purchased an EMP electric water pump, but I am convinced my cooling issues deal with airflow not water flow.  Installing an electric water pump is a major modification and lots of work only to find out it doesn't change a thing.  My next attempt will be to cut holes in the upper rear cowl to allow more air into the radiator area.  Hopefully this will be enough.  I want to keep the aesthetics of the smooth lines, but I need to have confidence I won't overheat if I need to hover longer than 10 minutes.

[Orv Neisingh]

Guys, I have found that this simple 18” transmission cooler from Amazon works very well, is in the cool outside air flow, and does not block coolant flow through the radiator. I have installed this on many ships with great results.

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Here is the top end of the oil cooler. I leave the tail boom bottom inspection covers off so the openings produce negative pressure sucking out the hot air from the engine compartment allowing cool air to be sucked in through the lower body panel side vents and flow over the oil cooler fins.

[Lyle Swallows]

the rotorway design works, just well enough. it was designed for simplicity, which often is the best route.

sadly we're at the edge of our performance envelope.

the biggest issue i see with the original rotorway design is the constant speed, fixed pitch fan. while simple and light, its inefficient. even old classic automotive cars/trucks used a viscous clutch fan to lock up the fan at high temps biting more are, and loosen up in cool conditions conserving that power and not wasting it on moving unnecessary cooling air. the rotorway fan just constantly pushes air, idle, 100%, hot, cold, its just constant.

thats the next issue, pushes air, thats another thing we can learn looking at those automotive classic cars they are all configured for pulling air through the radiator, not pushing. and when cars changed to electric fans they could have moved them to pushers to conserve more space, but they didnt because its significantly less efficient.

now lets talk about just cutting holes in the body panel to open the cowlings for more airflow, while this may work in the hover, you have to be careful in forward flight. the area you talk about right above the fan on the upper body is actually a lower pressure area, if this area is lower pressure than the bottom of the radiator it could actually fight against the flow of the fan. thats where the scoops come in, we need to have the opening in a high pressure area which we create with the scoops, and direct it to the radiator which sits at a natural low pressure area.

the electric water pump does nothing to help cooling except for at shutdown by allowing the engine to idle and the flow remains 100%. its also a complicated coolant circuit and it allows priming/bleeding convenience. but you lose simplicity of a belt driven system to one that needs switches, relays, and more current produced.

all improvements to be done at your own risk, and tested thoroughly with your results and procedures written into your checklists and aircrafts unique POH. if you already have your airworthiness cert the FSDO should be notified and modification noted/inspected by the FAA again. i chose to do mine now because of this.

long reply. sorry Tim.

[Tim Morris]

Orv, I had one of those supplied by Kasey.  I took it off and installed this instead.  Oil seems to be OK, H2O - not so much.

[Orv Neisingh]

Yeah, Kasey saw mine and put one in his ship. My water temp runs around 160-180 on hot days and oil temps are always below 200f.

[Graeme Smith]

Hi Tim,
You are highlighting the problem, and you are not alone, I see a lot of RWs hovering around with the lower rear panels off, this highlights the problem, simply put the radiator fan is sucking in hot engine air then trying to force it through the radiator, the water flow is not the issue, but I do prefer the EWP from Stewarts, also the water then is also trying to keep the oil cool, again it simply will not do a good job of either. A separate air to oil cooler mounted in the tub pulling outside air through it solves the oil temp issue, it is more efficient if you can create a NACA scoop as that draws in more air when in flight.
The answer is fully enclose the top of the radiator and draw air in from outside and put a fan on the bottom of the radiator.
It is not a really big job.

[Tim Morris]

Hi Tim,
You are highlighting the problem, and you are not alone, I see a lot of RWs hovering around with the lower rear panels off, this highlights the problem, simply put the radiator fan is sucking in hot engine air then trying to force it through the radiator, the water flow is not the issue, but I do prefer the EWP from Stewarts, also the water then is also trying to keep the oil cool, again it simply will not do a good job of either. A separate air to oil cooler mounted in the tub pulling outside air through it solves the oil temp issue, it is more efficient if you can create a NACA scoop as that draws in more air when in flight.
The answer is fully enclose the top of the radiator and draw air in from outside and put a fan on the bottom of the radiator.
It is not a really big job.

You are probably right Graeme.  I'm just not good enough with fiberglass to attempt.  But, the purpose of an experimental aircraft it to learn new skills.  I will never win best in show, but I want it to look somewhat reasonable.

[Graeme Smith]

If you can build a helicopter you DO have the skills to make the changes. Just find a local Urethane manufacturer Use the (green as the yellow is too soft) as they always have off cuts they throw in the bin, you can sculpture that to the shape then smooth it and apply a thin coat of car bog and sand till smooth, then apply wax and this becomes either the plug to make a mould or the part which you lay up on top of it and when completed you destroy the plug and you are left with the part, it will need a lot of detailing before painting