TacAero suspension test: Stock bungees, AOSS, TK1, and Acme "Black Ops" Gen3

[John Hodges]

TacAero, the CubCrafters authorized flight training organization, which also conducts advanced flight training for U.S. Government and Military organizations, is currently performing product development for a classified military program. As part of that program, TacAero recently evaluated several of the leading suspension systems for CC-11/CCX airframes. Because this subject matter interests the broader cub-flying community, TacAero was kind enough to allow CalCubs to share its report, which follows:*

December 12^TH, 2017

Strut Suspension Test for Carbon Cub FX-3 TacCub call sign “Black Bird”


Struts Tested:
1. Stock Bungees
2. Alpha Omega Suspension System – AOSS
3. TK 1
4. ACME AERO – Black OPS Gen 3

Test Purpose(s):
· To test, assess and identify a leading/superior shock option for specific TacAero customers.
No controlled studies comparing these strut options head to head were known or available for study.

Test Parameters:
· Test all 4 struts correctly installed and calibrated (per the rigging instructions associated with each strut) on the Carbon Cub FX-3 with 3+3 gear and 29” Bush Wheels / Scott 3200 Tail Wheel (N844FC).
· Test all 4 strut options at full gross weight (2000lb) & at ¼ tank fuel load, no other weight added other than the pilot (200lbs) and 20lbs weight in far aft position of storage compartment.
· All Landings will be controlled to the briefed landing area (rough, gopher hole infested, 1’-1.5’ dirt berm/lips, gravel, dirt and grass).
· 8 landings per strut set up. 2x per.
o 4-5’ full stall drop landing
o Cross Control 3-point landing to recovery
o One wheel landing / Drop
o Fast landing with brake control / response
· Go Pro attached to undercarriage for video data and comparison.
· Full Debrief after each tested strut.

Environmental: 12/02/17 - OAT 33deg F, Wind 080-070 / 4-5 knots / Ceilings 3000
12/07/17 - OAT 30deg F, Wind 080-070 / 4-5 knots / Ceilings 4500
12/11/17 - OAT 28deg F, Wind 080-070 / calm / Ceilings 4000
Pilots:
· Mike Sasser
· Jeremy Young

Test Days:
· December 02, 07, 11, 2017


TESTS

Stock Struts / Bungees

1. 4-5’ full stall drop landing
a. This test was modified for unsafe / unnecessary risk to aircraft. 2-3’ drops were performed instead of 4-5’.
i. Bungees performed as expected. Significant bounce and “springiness” experienced.
2. Cross Control 3-point landing to recovery
a. Results as expected / directional control standard with effort/skill. Significant wing dip and “hopping’ of the gear.
3. One wheel landing / Drop
a. Significant shudder, with associated anticipated bounce.
4. Fast landing with brake control / response
a. Sluggish response, shudder in the gear, expected response and outcome.

Notes- Stock struts offered a base line. Pros and Cons of this suspension are well known.



Alpha Omega Suspension System – AOSS

1. 4-5’ full stall drop landing
a. 1’-1.5’ consistent bounce at light weight configuration.
b. Loud “POP” with 1’ bounce at gross – unexpected.
2. Cross Control 3-point landing to recovery
a. Results as expected / directional control standard with effort/skill. Struts performed well.
3. One wheel landing / Drop
a. Springy feel on one gear. Gear slide on transition felt when contact was made by opposing gear.
4. Fast landing with brake control / response
a. Sinking feel when brakes are applied. Sluggish, dipping response when performing the wheel landing and applying brakes.

Notes- AOSS are a nice strut that performs well with a skilled pilot. Superior to the stock bungees.


TK 1

1. 4-5’ full stall drop landing
a. No bounce. Hard to tell when the gear actually touched the ground. Impressive absorption.
b. Great drop recovery at both light and gross weight configurations.
2. Cross Control 3-point landing to recovery
a. Very poor results. Aircraft wants to dart when one side compresses more than the other especially at gross configuration.
3. One wheel landing / Drop
a. “Squishy” feel on one gear. Darting tendency compounds significantly. Difficult to maintain control. Hard to tell when contact was made with the ground.
4. Fast landing with brake control / response
a. Sinking feel when brakes are applied. Sluggish, dipping response when performing the wheel landing and applying brakes. Almost identical feel to the AOSS.

Notes- TK 1 Struts look beefy and rugged. These shocks performed well with high drops and rolling over obstacles, bumps etc. These struts require an advanced pilot to maneuver and utilize in all the conditions tested.

ACME AERO – Black Ops Gen3 (heavy spring configuration)

1. 4-5’ full stall drop landing
a. No bounce. Hard to tell when the gear actually touched the ground. Extremely Impressive absorption.
b. In light weight configuration the gear is a little springy, but not as bad as the above tested struts.
c. Great drop recovery at both light and gross weight configurations. Uncanny, as the drop feels like a smooth, controlled, three-point touchdown.
2. Cross Control 3-point landing to recovery
a. Excellent feel and control. Gear is responsive with excellent feel and control.
3. One wheel landing / Drop
a. Solid, positive control. We are curious to test this gear in high crosswind conditions.
4. Fast landing with brake control / response
a. Positive response, gear reacts well with braking.
b. Absorbs bumps and uneven terrain without transferring energy to the cockpit.

Notes- The Gen3 struts performed far above expectation. From the online research TacAero did prior to this test, we thought the AOSS or TK 1 struts would be the best performers. The only struts from this test we did not purchase prior were the Gen3.
Hands down, the Gen3 was the highest scoring throughout this test. We have left the Gen3 Black Ops ACME AERO struts on N844FC. We are certain these are the struts our customer will need and live up to their name. We are anxious to do further testing with this set up and really put these struts through the fire as we continue to demonstrate to performance and capabilities of the FX-3.

*CubCrafters has scheduled the Acme "Black Ops" Gen3 suspension for a full landing gear analysis, including testing for fuselage structural loading and compatibility by the CubCrafters EPD test labs. CalCubs is not aware of any other suspension system that has undergone such analysis.

[jasimmons]

How many folks are running these? Owner pireps? Price?

Thanks,

Andrew

[John Hodges]

We've got around 20 sets in service. The Gen3 "Black Ops" suspension has just been introduced. We have a "Black Ops" set on our Carbon Cub demo, TacAero has a set on their military demo FX3, and Mike Sasser, the TX/OK/AK/LA dealer has a set on his FX3. Everybody loves the Gen2s, and the Gen3s are even better. The TacAero report is the basis of this post. Mike recently reported:

"As to the Acme Gen3 Black Ops well I just have one word……………..EPIC!!! Having flown the Gen 2’s and now the Gen 3’s I will tell you that the Acme boys listened to what Chuck, myself and others gave them in feedback and came back with a solid winner in this shock! It is almost impossible to make a bad landing with these shocks. In fact they will lull you into thinking you are much better than you really are. In my opinion they are so much safer than bungees its not even funny. From a demo standpoint you really can let the customer have the airplane and not worry at all about them dropping it in on the landings. Knowing how they will perform on a drop in is reassuring and makes it easier to teach a slower approach with confidence at the bottom."

Price is $3300 + ship & hand. Pop on down to SMX if you want a demo flight. We'll show you how much this suspension enhances your Carbon Cub flying experience. You'll want us to put a set on your airplane right here right now!

[Springloaded]

[QUOTE=jasimmons;20388]How many folks are running these? Owner pireps? Price?

Thanks,

Andrew[/QUOTE
Ive seen a lot of people putting all these new fangled shocks all over there cubs. Im not a gadget person and they have way to many moving parts for me. So when Ben Hodges which I have a tremendous amount of respect for tried to talk me into trying a set of Acmes, I was very skeptical. I liked the way the ACME looked but had serious concerns about the strength of the aluminum attachment arm and told him I would not put a set on my plane till they were tested under compression. He got ACME to test them and I was totally floored by strength of them. I now have 150hrs or so on them. Quite a bit of it off airport. They work extremely well, Ben described it to me perfectly. They are very compliant. I haven't had the opportunity to try the GEN3. They had a few little quirks that I wasn't use to, they were a little too soft so when your draging a new field you didn't feel how rough it really was, you could here them return when you dropped it in (sounded like bungee system) which I didn't like but they gave me some spacers to tighten in up which eliminated both issues. Only complaint I ever heard was the plane leaned side to side when taxiing on uneven terrain(these shocks actually move). I haven't seen it I taxi with tail up all the time making turns have never noticed it leaning excessively one way or the other. Acme guys were absolutely the best to deal with they were very receptive to my feed back, they came out and watched me in the OSH STOL demo and were fine tuning them everyday as I was giving them feed back plus they got to see the Suspension get worked pretty hard. After talking to Mike and Ben it sounds like they really got it nailed down with the Gen 3. I'm looking forward to flying a set. I sold my AOSS 😀

[John Hodges]

The testing "Springloaded" refers to involved placing stock bungees, AOSS, and Acmes in a test jig simulating a Carbon Cub 3x3 extended gear in compression, the most common failure mode for Cub gear. The Acme Gen2s tested 75% stronger than AOSS. The Acme Gen3 "Black Ops" were 250% stronger than AOSS. Bungees finished a distant third.

For the tech geeks, the Gen3 "Black Ops" shocks incorporate a high flow, linear digressive piston with a larger diameter shim stack than the Gen2s for greater low speed sensitivity. It's a full floating piston now, which is also base valve adjustable for greater high speed damping control. The Acme folks are race car suspension experts who have adapted that technology to aircraft. Its finely tunable hydraulics technology is light years more advanced than bungee cords, AOSS urethane biscuits, or even air shocks. It's why the TacAero folks, who really know what they're doing, evaluated the Gen3 "Black Ops" suspension as "hands down" the best.

[David H]

I just received two of these in the mail. Fantastic quality. No pireps for a while (?summer 2018). I am on hold waiting for PPS from Vertical Power (?February they said this morning)

http://verticalpower.com/index.php/products/pps


IMG-6359.jpg

[jim plaster]

Anyone in N.C. running a set of the Acme's? Sure would like a test hop!

[ncshp]

Anyone in N.C. running a set of the Acme's? Sure would like a test hop!

I have a set of Gen 2's on a 180HP Cub. I'm running a 3x3 gear with 27" Aero Classics. I've dropped it in from around 5-7 ft and it will totally absorb the drop with little to no bounce. Landed the other day on an old field full of large ant hills & big clusters of cut broom straw. I was expecting a rough ride once I got down low enough to really see what was under me but barely felt anything except for the larger aint hills and that mostly from deceleration. It will give you great landings but if you go back to an aircraft with bungees...look out!!

[jim plaster]

I'm running 26" Airstreaks on a CCSS and would love some rebound/dampening on the rougher runways. Even when aired down on the tires....the bird is like riding an old pogo stick when it's rough. Like the other guy....I'm concerned a bit about the aluminum strut. Still on the fence here.....maybe a New Years Sale will push me over edge on buying a set...lol! Are you running and safety cables as an insurance policy on the aluminum strut?

[John Hodges]

The Gen3 Black Ops shocks have a hybrid stainless alloy shaft (see David H post below) and heat treated chrome moly body lugs. In compression, the most common failure mode (for which safety cables are useless), the Gen3s are three times as strong as a stock bungee setup, and over twice as strong as AOSS. In tension they've been tested to 20Gs at 2000lb gross. They are way stronger than anything else that we're aware of. That said, safety cables are good insurance, and we recommend them for severe duty -- for any suspension. And they look bad-ass. ACME has composite safety cables in the development queue, but it's behind some others. Hint -- it involves the opposite end of the airplane from the Gen3 Black Ops.