Why We Removed The Supercharger

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Antoine
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Re: Why We Removed The Supercharger

Post by Antoine »

I want to say clearly that my only intent going forward is to understand, not point fingers.

Chris: your aircraft being a 2008 must have the tuned exhaust which is good for a significant increase in climb rate versus non-Powerflow planes such as Brock's. If this is correct, I must pull back my statement that you should compare with Brock.

Brock reported rather spectacular gains on his plane that led him to "donate" several years of his plane's life to getting this STC'd - after seeing the benefits.

A small correction to Ian quoting me:
"it is common for turbocharged aircraft to run 120-140° IAT increase over ambient after their intercoolers."

This is how I operate my turbocharged engine:
max continuous IAT (not IAT increase): 130 F
redline IAT: 140 F (tolerated for less than 1 minute at top of climb on hot days).

It is worth noting that in turbocharged planes, the amount of compression and related heat are controlled by the wastegate and gradually increase as the plane gains altitude and air density decreases. Note that the wastegate does not dump compressed air, just excess exhaust energy.

Outside air temperature decreases with altitude, mitigating some (but not all) of the IAT temperature increase. In my plane, max IAT always occurs at top of climb, just before level off.
My modest experience of turbocharging and the overheat issues I have faced make me fully agree with Ian's statement below:

"We decided that the minimal gain we would get from adding intercoolers would not justify the additional cost, weight and complexity".

... especially keeping in mind that an intercooler will actually "eat" some of the MP. If temperatures are low enough, intercooling can actually degrade overall system performance by requiring more boost, and not shedding enough heat to pay for it...

This said, the reports show that none of the supercharged planes are able to exploit full sea level MP beyond take-off without hitting excessive CHT. What is your take on this Ian? Would a smaller charger make more sense?
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Ian Sage
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Re: Why We Removed The Supercharger

Post by Ian Sage »

Antoine wrote: Fri Jun 05, 2020 12:18 am I want to say clearly that my only intent going forward is to understand, not point fingers.
. . .
Your intent is understood and I (hopefully nobody else either) have not taken issue with anything you have said here. I appreciate the open dialog.
Antoine wrote: Fri Jun 05, 2020 12:18 am . . .
A small correction to Ian quoting me:
"it is common for turbocharged aircraft to run 120-140° IAT increase over ambient after their intercoolers."

This is how I operate my turbocharged engine:
max continuous IAT (not IAT increase): 130 F
redline IAT: 140 F (tolerated for less than 1 minute at top of climb on hot days).
. . .
Since the quote was back on a previous page I was trying to work off of memory. Thank you for the clarification. I certainly was not intentionally misquoting you.
Antoine wrote: Fri Jun 05, 2020 12:18 am . . .
It is worth noting that in turbocharged planes, the amount of compression and related heat are controlled by the wastegate and gradually increase as the plane gains altitude and air density decreases. Note that the wastegate does not dump compressed air, just excess exhaust energy.
. . .
With our supercharger system the amount of total temperature rise from compression is controlled by engine RPM. The actual IAT rise inside the intake manifold is less than that at sea level and peaks at about 7000'. Above that the IAT rise starts to decrease again as the supercharger is no longer able to maintain full manifold pressure. Note that the supercharger does not have a wastegate and also does not dump excess compressed air. Rather at any altitude below 7000' +/- the throttle is partially closed effectively blocking the boost. This provides two benefits at lower altitudes.

First, if the supercharger is compressing say 36" of pressure, but the throttle is only allowing 30" of pressure into the manifold by restricting the flow . . . in the same way that compressing air heats it up, decompressing air cools it down. The cooling effect is not a 100% return but there is a partial cooling effect at any partial throttle setting. Second, when the throttle is holding boost back the supercharger takes less HP to turn. It actually saps the least direct horsepower from the engine near sea level.
Antoine wrote: Fri Jun 05, 2020 12:18 am . . .
Outside air temperature decreases with altitude, mitigating some (but not all) of the IAT temperature increase. In my plane, max IAT always occurs at top of climb, just before level off.
. . .
Since our "critical altitude" where sea level manifold pressure can no longer be maintained is 7000' +/-, that is where both the highest parasitic draw and highest IAT rise are usually observed. Any altitude below that both are lower for the above described reasons. Any altitude above that both are lower simply because air compression rate for a given compressor is not linear as air density drops.
Antoine wrote: Fri Jun 05, 2020 12:18 am My modest experience of turbocharging and the overheat issues I have faced make me fully agree with Ian's statement below:

"We decided that the minimal gain we would get from adding intercoolers would not justify the additional cost, weight and complexity".

... especially keeping in mind that an intercooler will actually "eat" some of the MP. If temperatures are low enough, intercooling can actually degrade overall system performance by requiring more boost, and not shedding enough heat to pay for it...
. . .
BINGO!!! Intercoolers are full of small passages and surface area. They are very flow restrictive and a net loss when they are not cooling air.
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TimS
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Re: Why We Removed The Supercharger

Post by TimS »

Ian,

Curious, what is the max temp rise due to compression with your solution?

Tim
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Chris B
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Re: Why We Removed The Supercharger

Post by Chris B »

Ian Sage wrote: Thu Jun 04, 2020 9:24 pm…feels as though we did not disclose any of what he sees as the drawbacks adequately which is something that we always try to do.
The lower cowling *cannot* be removed or installed without detaching the spinner. This is not documented in the supercharger installation instructions, ICA, or AFM supplement. We discovered this during installation while conferring with a nearby shop about their supercharger installation experience.

We spent a great deal of time on the phone with Chris trying to help him through his installation issues and eventual disappointment in both the performance and CHT rise. Unfortunately we never got to see the plane ourselves and I am confident the issues he encountered during the installation could have been quickly remedied.
I did not dwell on installation issues because that did not directly factor in our decision to remove the supercharger. But one is relevant to this discussion.

By far the biggest installation issue was that the cowling modified by FAT (after $700 round-trip shipping) did not fit. The lower cowling was literally resting on the pulley.

Here is a borescope photo taken through the gap behind the spinner bulkhead with both upper & lower cowlings installed. "Up" is at 1 o'clock. Obviously this is a problem.
Image

Additionally, despite the installation being signed off as complete we have been told by another mechanic who has worked on the plane that the supercharger was not installed per the STC. The alterations he described absolutely would have negatively impacted both CHTs and performance. Unfortunately not knowing that until after the fact makes many of our attempts to provide support from afar futile.
I strongly disagree that any performance issues were due to “alterations” which Ian knows were only temporary. But were needed to rework the cowling FAT modified.

Our airport has no on-field composite specialists. Nearby Alpine Aviation specializes in Diamonds, and recently installed a FAT supercharger with a similar cowling issue. Alpine was willing to squeeze us into their busy schedule, but needed the airframe to ensure a good fit. We made a small relief opening in the cowling which my IA judged was not an airworthiness issue, and flew the aircraft to Alpine. We had also originally installed GAMI injectors, but Alpine reinstalled the injectors supplied by FAT. This improved climb CHT.

Alpine reworked the cowling and followed-up with test flights to ensure that the supercharger was operating as expected. After fixing the cowling and swapping injectors they reported that it performed the same as their previous DA40 FAT supercharger installation.

And the data clearly indicate that our supercharged aircraft performed the same as Wayne's and Brock's.

The data also indicate that there was no meaningful climb performance improvement to 11,500' compared to our normally aspirated configuration. Unless FAT could have somehow made N171CB climb substantially better than N211WP or N8QQ.

We are sad to loose [sic] Chris as a customer, particularly when unresolved technical issues contributed to his decision. It is in our best interest to be as responsive and supportive of our customers as possible. For a company who strives to provide an excellent product and support with an industry leading warranty each unhappy customer is a bitter pill to swallow and loosing [sic] Chris is no exception.
There were no “unresolved technical issues” after Alpine Aviation completed their work.

We are still waiting on FAT’s April commitment to reimburse us for the cowling rework. And disappointed that with <12 hrs logged, only offered to "possibly purchase some or all of the system" if it “were complete and in good condition after inspection” for "around $4-6000.

Chris
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Ian Sage
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Re: Why We Removed The Supercharger

Post by Ian Sage »

Antoine wrote: Fri Jun 05, 2020 12:18 am . . .
This said, the reports show that none of the supercharged planes are able to exploit full sea level MP beyond take-off without hitting excessive CHT. What is your take on this Ian?
. . .
I suppose the best place to start is the extreme end and dial back from there. The FAA testing we are required to do on all of our systems include a grueling full power sustained climb to service ceiling. For the purposes of this test the FAA does not care about how you like to fly your aircraft. They do not care how we might intend our product to be best used. They don't care about lean of peak, the red fin, what your instructor taught you or conserving fuel for an efficient flight. They only care about the outside air temp and the manufacturer limitations on the airframe and engine. To pass the test we must push the plane at Vy and stay with the manufactures documented limitations. Effectively this means the oil temp and CHTs must remain in the normal operating range. While the numbers you find in the DA-40 POH may be higher than the majority of us consider acceptable, they are the extensively tested and proven safe limitations as published by the manufacturer.

Producing more power always goes hand in hand with producing more heat. To pass this test we ensure the baffle is in tip top shape and the oil cooler is not obstructed or damaged. Those are things I recommend for all planes. Specific to the DA-40 there are changes to the fuel system in both the servo at the throttle body and the individual injectors themselves providing both more maximum flow and better atomization. The combination of optimum cooling air through the cylinders, the additional available fuel and the fact that we start loosing power at roughly 7000' (thus running cooler and cooler as climb continues) make it possible for us to pass the grueling climb cooling test within the manufacturers limitations.

Knowing that it does pass when following the POH to the most aggressive sustained climb allowed one must understand that any change to climb angle, RPM, fuel flow, baffle condition, personal limitation that is more restrictive than the POH, etc., etc. adds another variable that may increase or decrease temperatures and must be accommodated accordingly. I have met very few people who's normal mission includes a sustained max power climb at Vy or Vx. I have met a few who don't care how much fuel it takes to go fast, they just want to go fast. Most of us have developed much more moderate operating habits. Adding a turbo, supercharger, changing engines, aero changes like a STOL kit or changing planes entirely will all require modifications to an individual pilots normal operation to operate the new aircraft.

For instance, as discussed elsewhere the supercharger introduces heat with diminished performance at low altitudes so cooling air is not as readily available as it would be above 3000'. Climbing ROP with a little extra fuel for cooling may make more sense. Another pilot might not be unwilling to add fuel to keep cool, so they could reduce power or climb angle until they were at a more advantageous altitude. Then again, if they don't want to produce more power the supercharger may not be a good option in the first place.

I'm not sure if that answered your question or if it just came across as a word salad. If not let me know and I will try to pinpoint a clearer answer.
Antoine wrote: Fri Jun 05, 2020 12:18 am . . .
Would a smaller charger make more sense?
To keep it fairly short and simple, a smaller charger requires higher internal RPM. Smaller housing means smaller internal gearing. That requires smaller supercharger pulley with less belt contact area. Less contact area means more potential for belt wear and failure. So we chose the largest unit that would fit inside the cowl and operate efficiently. The bump provides room for the pulley to stick out far enough to align with the ring gear pulley on the crank so it would still be necessary regardless of supercharger size.
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Ian Sage
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Re: Why We Removed The Supercharger

Post by Ian Sage »

TimS wrote: Fri Jun 05, 2020 2:55 pm Ian,

Curious, what is the max temp rise due to compression with your solution?

Tim
Tim,

80° is the maximum temperature rise over OAT under the least favorable conditions. That is achieved at 7000' +/- and would be lower both above and below.
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Ian Sage
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Re: Why We Removed The Supercharger

Post by Ian Sage »

Chris B wrote: Fri Jun 05, 2020 4:54 pm
Ian Sage wrote: Thu Jun 04, 2020 9:24 pm…feels as though we did not disclose any of what he sees as the drawbacks adequately which is something that we always try to do.
The lower cowling *cannot* be removed or installed without detaching the spinner. This is not documented in the supercharger installation instructions, ICA, or AFM supplement. We discovered this during installation while conferring with a nearby shop about their supercharger installation experience.
. . .
It is true that the spinner must be removed to remove the lower cowl. I know many mechanics to remove the spinner of any aircraft they are working on to avoid dinging it. While the fasteners do have a lifespan they are the same fasteners that are used on the actual cowl of many planes like the Cirrus SR-22 and SR-20 which all need to be removed for any inspection or maintenance. If this was going to be a deal breaker I do wish it had been clear sooner.
Chris B wrote: Fri Jun 05, 2020 4:54 pm
We spent a great deal of time on the phone with Chris trying to help him through his installation issues and eventual disappointment in both the performance and CHT rise. Unfortunately we never got to see the plane ourselves and I am confident the issues he encountered during the installation could have been quickly remedied.
I did not dwell on installation issues because that did not directly factor in our decision to remove the supercharger. But one is relevant to this discussion.

By far the biggest installation issue was that the cowling modified by FAT (after $700 round-trip shipping) did not fit. The lower cowling was literally resting on the pulley.

Here is a borescope photo taken through the gap behind the spinner bulkhead with both upper & lower cowlings installed. "Up" is at 1 o'clock. Obviously this is a problem.
Image
This was terribly unfortunate. To date it is the only one we have modified and returned without the plane here. We have had a couple of other shops do the mod and have similar issues. We believe we have identified the issue and are revising our instructions for the composite work going forward.
Additionally, despite the installation being signed off as complete we have been told by another mechanic who has worked on the plane that the supercharger was not installed per the STC. The alterations he described absolutely would have negatively impacted both CHTs and performance. Unfortunately not knowing that until after the fact makes many of our attempts to provide support from afar futile
We had also originally installed GAMI injectors, but Alpine reinstalled the injectors supplied by FAT. This improved climb CHT.
Meaning not installed per the STC. There was more than just those four injectors and temporary cowl modification. I will not participate in a descent further into these details on the forum.
We are sad to loose [sic] Chris as a customer, particularly when unresolved technical issues contributed to his decision.
There were no “unresolved technical issues” after Alpine Aviation completed their work.

We are still waiting on FAT’s April commitment to reimburse us for the cowling rework. And disappointed that with <12 hrs logged, only offered to "possibly purchase some or all of the system" if it “were complete and in good condition after inspection” for "around $4-6000.”
I am confident that the specific work performed by Alpine was completed correctly. They did not perform the entire installation though. I will need to check on the reimbursement for the cowling rework as Rod is not here with me as I type this.

As an FAA/PMA facility we are extremely limited in our ability to resell previously sold parts. The supercharger for instance is serialized to your aircraft. We are required to re-inspect and test it. Any defect will require it to be rebuilt and retested again. Each part has a paper trail of material certs and inspections to perpetuate. On the less complex side every nut, bolt, washer and clamp has a value that must be accounted for. Some parts can not be resold at all. For a kit that we already know had installation issues it is impossible for us to know what parts will be included and what their condition will be in. We made an offer to the best of our ability as a showing of good faith but as I explained above we are heavily constrained by our PMA status. While an owner can simply sell a used system we as the manufacturer can not.
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Chris B
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Re: Why We Removed The Supercharger

Post by Chris B »

Ian Sage wrote: Fri Jun 05, 2020 7:24 pm There was more than just those four injectors and temporary cowl modification. I will not participate in a descent further into these details on the forum.
I was deeply involved in the installation. AFAIK the GAMI injectors (commonly used via STC with both OEM and add-on forced-induction engines) and temporary cowling modification were the only material variations from the installation instructions.

Other small variations included two relatively minor fit issues (one resolved by FAT rework to the filter airbox, the other resolved by modifying the air block bracket after consultation with FAT), shortening one fuel hose to simplify routing after consultation with FAT, and an additional Adel clamp to secure the alternate air cable. I suggested other more substantial changes to improve installation & serviceability, but we did not implement these.

Seriously, I would like to know what you are talking about. :scratch:

For a kit that we already know had installation issues it is impossible for us to know what parts will be included and what their condition will be in.
What installation issues? (besides the cowling, injector and other fit problems noted above)

The data clearly indicate that our supercharged aircraft performed the same as Wayne's and Brock's.

I am confident that the specific work performed by Alpine was completed correctly. They did not perform the entire installation though.
Sure, but they were also asked to check for *any* issues, and have recent experience installing your supercharger. Alpine did not recommend any changes other than the cowling and injectors.

We made an offer to the best of our ability as a showing of good faith but as I explained above we are heavily constrained by our PMA status.
Your offer focuses solely on the residual parts value, and does not address the substantial STC value reflected in the system cost. As I indicated to Rod, I was simply hoping for a mutually agreeable return, not a total refund.

While an owner can simply sell a used system we as the manufacturer can not.
What is your fee to legally transfer the STC paperwork to the recipient of the used system?

Rod had previously indicated that this was not possible, but perhaps we miscommunicated.

Chris
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Re: Why We Removed The Supercharger

Post by Antoine »

With all due respect to both parties, I believe it would be wise to take this dialogue private.
It is very sad that this problem happened and I hope you find an amicable middle ground. good luck in the resolution and thank you for a very instructive and civil exchange
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Re: Why We Removed The Supercharger

Post by Chris »

Antoine wrote:With all due respect to both parties, I believe it would be wise to take this dialogue private.
Sorry for not posting this sooner and closing the thread. I contacted Chris and Ian on Saturday to recommend the same, and both agreed that there wasn't much use in continuing the public thread. I'll close the thread now, but if there is any need to post a follow-up later, I can re-open it.
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