ForcedAeroMotive: SuperCharged DA40

Any DA40 related topics

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rwtucker
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Re: UPDATE: ForcedAeroMotive: SuperCharged DA40

Post by rwtucker »

BRS wrote:One of those changes is that we must use a custom blended fuel with an octane rating of 99.6 to 101. The technical center says most 100LL from the pump is 103-104 octane. The technical center folks gave us their supplier for fuel and I am attempting to secure a drum for the test.
This slightly lower octane 100LL is just for the revised detonation test, right?
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Re: ForcedAeroMotive: SuperCharged DA40

Post by BRS »

Right. Not sure if the pump spec actually allows values as low as 99.6 (I suspect 100 is guaranteed) but if we use pump fuel that happens to be 103 (which seems likely) then there is no guarantee that we will pass at 100 which could be an issue when someone finds pump fuel that is right at the lower limit. It's a closely controlled test so all the parameters must be controlled.
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Re: ForcedAeroMotive: SuperCharged DA40

Post by Antoine »

trepine wrote:So just curious. Do you have any stats for say 15,500 or 16,500. Looking to run 2450 rpm both ROP and LOP.
A theoretical answer:

The Supercharger's critical altitude is 7100 ft as stated above, my guess is that it will deliver:

- Sea level climb rates all the way to 7000 ft, thereafter declining gradually. This is in my view the biggest benefit. Not only will the plane operate safely in hot and high conditions, it will be faster from A to B because the climb phase will be shortened. If you fly say at FL 100 for cruise, you will gain 3-4 minutes on the way up. Convert this into an increase of speed on the "horizontal" portion of the flight and you'll see quite a percentage gain.

As to cruise speed, it is a relatively simple ballpark calculation: it takes less and less power to fly at a certain speed as we climb higher because air density is lower. But engine power also decreases as the normally aspirated engine inhales a fixed volume of less dense air, thereby being able to burn less and less fuel.
The rule of thumb for speed increase with altitude at a given engine power setting (say 75%) is 2 KTAS faster per 1000 feet. This ballpark can be verified with the DA42-TDI which is (conveniently) about as fast as the DA40 while being turbocharged.
The DA40-180 delivers 75% power to about 8000 feet (fuel burn: 10-10.5 GPH ROP). so we should see no significant gain below say 8000 feet if we limit cruise power to 75%

Now let's climb further into "O2 territory"
At 12'000 feet, expect 8 knots more, at 14'000 feet 12 knots and at 16'000 feet at total of 14 extra knots compared to the original 8000 feet 75% cruise.
If the plane was doing 146 KTAS at 75%, it will hit 160, consistent with Brock's findings.

This neglects the fuel cost of running the supercharger, somewhat compensated by the ability to achieve 75% at lower RPMs which also saves gas. So the 160 KTAS is - from the above calculation - a good guess.

To sum it up:
The supercharger gives us the ability of taking off hot and high safely, climbing above terrain and quite a lot of the en-route weather at a solid IFR climb rate and staying very fast up high.
It turns the DA40-180 into a medium altitude cruiser and will require a good O2 installation to perform best. This considerably expand the envelope of this wonderful trainer!

(We can also take a look at the AFM of the DA40-NG and for an idea of what a similarly powered plane does).
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Would you pay $65.74 for a gallon of fuel?

Post by BRS »

Would you pay $65.74 for a gallon of fuel? We just did. In fact we purchased 54 gallons, to be exact, at that price. As painful as that was it, it was my pleasure to write the check because this will fulfill our last test in a long long taxiway to STC. Below is a note from Rod.
Hello everyone,

We completed the vibration test last week. This is another test we have never had to do before for an STC. This involved a dual laser rotational vibrometer at the crankshaft and an accelerometer on the supercharger mount. Vibration was then measured with and without the supercharger on the plane. Vibration levels on average were much lower with the supercharger operating at both the crankshaft and the supercharger mount, which means we have not introduced any detrimental vibration to the aircraft.

At this time we have one test left, detonation. Our drum of extra low octane fuel, specially blended for this test, at a cost of $3550.00 for 54 gallons, is supposed to ship this week. This is once again something we never had to do before. I should have asked if shipping is free if you pay over $60 per gallon.

Once the fuel arrives we will get set up and make some runs to be sure everything is working as it should and complete the detonation testing. I hope April sees our testing complete and our test results submitted for approval.

Rod
Note: The reason for the "extra-low-octane" custom blend is to make sure that under all fueling conditions we will not have a detonation issue. I'm told that typical 100LL is actually 103 to 104 octane. One can assume this is to provide for margin of error and fuel that has been allowed to get old. The fuel companies have a lot to loose if their fuel is ever delivered below 100 octane and an accident results. I believe our custom blend is supposed to be at 99.6 octane.

This is our last test. Almost there, thank you all for your patience.
-brs
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UPDATE: All tests are done!!!!

Post by BRS »

We have finally completed all the tests. Now to the paperwork. Here is a note from Rod at Forced Aeromotive.

-brs
Hello everyone,

Yesterday we finished the detonation test, the last of the tests on our approved test plan. We had no detonation at all. We used about 22 gallons of fuel, about $1500 worth.

We are working now on the test report, a document probably 280 pages or so that will explain each test, the result, and conclude that all the regulations have been met.

Thanks for all your support.

Rod
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Re: ForcedAeroMotive: SuperCharged DA40

Post by BRS »

Hi All,

Thanks for the prompt. I'll update you as best as I can. As you know from the last update (14Jun15) the tests are done. The initial reports have been drafted and submitted to our very busy DER. He has a full time job and family.... yada yada yada .... so getting to our documentation is not his first priority. But he is very good at what he does so we are content to wait until he can get to it. We still have one point of negotiation with the FAA before we can turn in the paperwork anyway. So until we come to an agreement, there is no hurry on the other reports etc.

I started this thread on 20MAR11. Over four years ago, wow! It has been a long road but we are not yet across the finish line.

I finally got my plane back home and it looks like it's going to stay. It still has a big EXPERIMENTAL sticker on both sides. The good thing is, it's in "Market Survey" meaning it's available for those of you nearby, who want to take a demo flight and check it out to see if this modification is for you.

My home base is W52 in Washington state, a 2500' grass strip (20 miles North of Portland OR). Though I'd likely meet you some place with more margin. Anyway, feel free to drop me an email at [brs'at'19301.net].
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Re: ForcedAeroMotive: SuperCharged DA40

Post by Chris »

I was fortunate enough to score a ride in Brock's SuperCharged DA40 today. I must say I was very impressed with the climb rates available at altitude. On a moderately warm day, and without trying particularly hard, we were seeing 600fpm at 12,000' on 12.6 GPH and 83 KIAS. Cruise performance was also quite good, with about 154 KTAS at 12,500' running on 8.3 GPH. It was seriously eye-opening how quickly we were able to climb to that altitude. I looked down over my "home base" and realized I'd never seen it from that altitude before. For anybody who does even a moderate amount of mountain flying, the extra safety margin makes this a slam dunk in my opinion.

Managing the throttle to prevent overboost would take a little getting used to, especially during go-arounds when the workload is already high. I expect it would become second nature after a while, though, and there's apparently an alarm that will sound to remind you if you hit the limit of 30".

Many thanks to Brock for his time, efforts, and expense in getting this STC near the finish line and for taking the time today to give me a demo of the capabilities.
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Re: ForcedAeroMotive: SuperCharged DA40

Post by Antoine »

Chris wrote:Cruise performance was also quite good, with about 154 KTAS at 12,500' running on 8.3 GPH.
"Quite good" is a small understatement. 8-) You have me begging for more detail because this speed to fuel flow is nothing short of unbelievable! What RPM were you running - and did you try more ff?

I am very jealous, Chris!
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Re: ForcedAeroMotive: SuperCharged DA40

Post by Chris »

Antoine wrote:
Chris wrote:Cruise performance was also quite good, with about 154 KTAS at 12,500' running on 8.3 GPH.
"Quite good" is a small understatement. 8-) You have me begging for more detail because this speed to fuel flow is nothing short of unbelievable! What RPM were you running - and did you try more ff?
I believe we were running at 2500 RPM at that point, but I'm not positive. I didn't take many data points since we were busy chatting about the system, but I made another entry of 151 KTAS at 12,400' and 8.4 GPH, which isn't quite as good, but still respectable. In general, we were trying to replicate what my typical climb and cruise profile would look like with the extra performance.
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Re: ForcedAeroMotive: SuperCharged DA40

Post by Joey »

Brock, did you get your STC?
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