• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

Suspension Test

Send him enough for my set too Glenn. I’m hoping to save up for a good summer, but the well is dry right now.


Sent from my iPhone using SuperCub.Org
 
I have the first set of Acme Aero suspension built for a Rans S-7S.
Many hours later the set still works excellant.
Roddy
 
Tom you will not regret them. I have a set of Gen2's on my Cub with 27's and 3x3 gear. The make for a smooth ride and will take hard landings and turn them into a soft touch down
 
I am running the TK-1’s on my Exp 12. They are impressive to say the least and I am very happy thus far. I do not find or experience any of the negatives noted in regards to darting in any capacity...one wheel landing, cross control etc. in fact I find them very stable in all situations to date. They sure suck up the bumps... landed in some pretty rough places, side hill beach landings, one wheel X-wind... inside corner type beaches... no issues.
 
Last edited:
I also have been flying the tk-1’s for a bit less than a year. I’m wondering what they did to get the negative results they got. What tires? The set up? Not sure but have not experienced any of the negatives that they mention. I really really like them. I was never happy with the AOSS, I know lots of people like them but mine were very disappointing.


Sent from my iPad using SuperCub.Org
 
Interesting results,
I assume Acme "Gen 3" is the result of growing pains encountered with their previous generations.
Gen 1 cost at least one early patron a prop and a bunch of body work.
I wouldn't abandon the safety cables just yet..
IMG_1748.jpg
 

Attachments

  • IMG_1748.jpg
    IMG_1748.jpg
    137.1 KB · Views: 1,578
Another point...I was on an airplane recovery last week here in Prince William Sound...I am certain if the guy would have had TK-1’s this would have been a non event...however the suspension he had failed and resulted in a blown Catto, tore up gear leg and busted wing. Bottom line TK-1 Truly sucks up the rough stuff.
 
Interesting results,
I assume Acme "Gen 3" is the result of growing pains encountered with their previous generations.
Gen 1 cost at least one early patron a prop and a bunch of body work.
I wouldn't abandon the safety cables just yet..
View attachment 34428

THAT failure was a VERY obvious/predictable failure that we pointed out at first glance at that design!! unless you were an engineer ....
 
Another point...I was on an airplane recovery last week here in Prince William Sound...I am certain if the guy would have had TK-1’s this would have been a non event...however the suspension he had failed and resulted in a blown Catto, tore up gear leg and busted wing. Bottom line TK-1 Truly sucks up the rough stuff.


Stock bungee gear or something else?

thx
jim
 
Interesting results,
I assume Acme "Gen 3" is the result of growing pains encountered with their previous generations.
Gen 1 cost at least one early patron a prop and a bunch of body work.
I wouldn't abandon the safety cables just yet..
View attachment 34428

Good morning everyone. We appreciate the interest and conversations going on about our shockscurrently. I wanted to take a minute andaddress the one failure we had shown in the picture. This set of shocks absolutely failed and as aresult we contracted a third-party engineering firm to determine why it failedand recommendations on how to keep that from being an issue in the future.

Prior to the release of any of our products we conduct thirdparty destruction testing both in extension and compression. We knew upon the release of the Gen 1, thatparticular shock would break at 18,000lbs in a straight line pull test and itwould break at 3,500lbs in a simulated side load or compression test. (For comparison, a standard Super Cub bungeebroke at 1,600lbs and an AOSS broke at 2,200lbs)

The third-party firm we contracted after the failure deemedthat the failure was a result of the shocks “operating outside of the normal capabilities”. A frontal load was applied which resulted ina twisting force.

The firm also suggested we use a hardened chromoly to helpguard against this issue in the future. Even though the third-party signed off on the strength and design asmore than sufficient as a company we offered an upgrade to the new cap with nocharge and we’d cover shipping. Basically,we saw an opportunity to make our product stronger and we made it happen.

With the latest Gen 3 Black Ops Shocks, we saw opportunitiesto improve and we incorporated them into this design. As a company we always want to improve, if youre not going forward youre going backwards. We went with a new hybrid stainless shaft construction simply because we found in testing that the shocks will now make it to 5,000lbs before they yield and will return to their normal resting state with minimal run out. We also made some valving changes on the performance side. The Black Ops shocks have been extremely wellreceived from anyone that has flown them and they are definitely a set ofshocks we are proud of and think perform great with a premium on safety. With that being said, we arealready thinking about how to improve and what we would like to see in the Gen4’s. (Don’t worry Gen 3 owners, it’ll bea few years from now. We have that tailwheel design we are in the final stages of testing on and will be ready by SunN Fun.)

We really hope this clears some things up for everyone. Bottom line, whether its Acme, AOSS, or TK1,I know we are all out here working our tails off to build the best products wecan and you can’t go wrong with any of them.

If you have any other questions please don't hesitate to ask.
 
Thanks for taking a moment to chime in.
Im not understanding the "frontal load" factor you had described - assuming the main gear and fuselage attach points survived intact. Did the shocks/struts physically contact something?
Regardless of the forces at play, (some difficult to anticipate or simulate) I would assume original hardware, i.e. bolts, cabane, main gear or attach points, should fail before any aftermarket shock components.
Im not aware of the circumstances surrounding the failure depicted in the photo, but your statement would indicate that shock components were under engineered requiring measures taken to correct them.
That being said, the poor fellow who suffered the catastrophic failure and subsequent damage was (unknowingly) part of your R&D process, I certainly hope he was fully compensated for cost of repairs.
I would be interested to hear more about the outcome. I think how these growing pains are resolved speaks volumes about the integrity of businesses and ones willingness to embrace their products.

There was an earlier thread on this very topic, Interesting to review following this latest conversation.
 
Last edited:
Thing to remember, is the fact that we are buying experimental non certified parts. Running with safety cables should be seriously considered. The picture shows not just one shock but both failed at the same time. Attention getting for sure, however, broken suspension and damaged cub explains very little ultimately. Not near enough info to say “it’s the suspensions fault.” It could be indeed, only the pilot flying that plane, others that saw the incident or the aircraft’s engineer could accurately pass judgement. A hard enough landing can break the toughest of gear.
Roddy
 
Roddy,
"experimental" or not, if I'm going to spend $3000+ on a critical airplane component it better damn well be at least as strong stronger than the part it was designed to replace. To my knowledge the AN bolts on each end of the rods were the weak link in stock gear subjected to linear landing/taxiing loads.
The fact that both shocks failed simultaneously (fortunately, otherwise a cartwheel) adds credibility to the fact that both were subjected to the same load at the same time in the same direction and failed at the weakest point.

and yes, I agree with you on safety cables
 
Last edited:
At this point the failure has been noted and a cure delivered, seems like a few gen's in the past as well. A lot of early product sucked, so whats the take on the current product.
 
I have a question for AcmeAeroFab. Is there a mechanical spring in your shocks? So in the event of a seal leak the shock won’t go flat? I know there are no springs in my TK1s and without gas pressure they do go flat. Maybe that’s why there are redundant shocks on both struts? I don’t know anything about that. Typical gas shocks that I’m familiar with use internal floating pistons. It’s all about keeping the oil from frothing. There’s no floating piston in my TK1s, but riding a hundred miles in the bumps isn’t the mission. How these shocks are evolving for airplane-specific use is fun to watch.
 
Last edited:
I have a question for AcmeAeroFab. Is there a mechanical spring in your shocks? So in the event of a seal leak the shock won’t go flat? I know there are no springs in my TK1s and without gas pressure they do go flat. Maybe that’s why there are redundant shocks on both struts? I don’t know anything about that. Typical gas shocks that I’m familiar with use internal floating pistons. It’s all about keeping the oil from frothing. There’s no floating piston in my TK1s, but riding a hundred miles in the bumps isn’t the mission. How these shocks are evolving for airplane-specific use is fun to watch.

Yes. Our shocks are internally sprung with separate internal dampening. In the event one of our shocks ever loses gas pressure or there was a seal failure we would simply lose dampening aspect.
 
Thanks for taking a moment to chime in.
Im not understanding the "frontal load" factor you had described - assuming the main gear and fuselage attach points survived intact. Did the shocks/struts physically contact something?
Regardless of the forces at play, (some difficult to anticipate or simulate) I would assume original hardware, i.e. bolts, cabane, main gear or attach points, should fail before any aftermarket shock components.
Im not aware of the circumstances surrounding the failure depicted in the photo, but your statement would indicate that shock components were under engineered requiring measures taken to correct them.
That being said, the poor fellow who suffered the catastrophic failure and subsequent damage was (unknowingly) part of your R&D process, I certainly hope he was fully compensated for cost of repairs.
I would be interested to hear more about the outcome. I think how these growing pains are resolved speaks volumes about the integrity of businesses and ones willingness to embrace their products.

There was an earlier thread on this very topic, Interesting to review following this latest conversation.

We certainly appreciate your response. Whereas I usually make it a point not to rebut posts on forums the picture without details is pretty damning. I'm not going to put the details of the report out there nor will I distribute any pictures of the site where the accident happened. What details I will add is prior to the release of the Gen 1 shocks we conducted the standard FAA drop test but went far beyond that in our own testing. We still wanted to know the number at which they would fail and the shocks failed at 18,236lbs in extension. Prior to achieving a failure we broke a 5/8" grade 8 bolt. I don't know of any other company that has actually tested their shocks to destruction using an independent third party AND has made those numbers as well as the videos public.

If forces are applied to the shocks that are outside the normal use it's impossible for us to account for that and impossible to test. What we did as a company is used the opportunity to make it even stronger to guard against failure with the type of load those particular shocks were subjected to even though that load is still outside of normal operating parameters.

One “oh crap” cancels out 10 “attaboys”. We have over 150 sets of Gen 2’s flying and haven’t had any issues whatsoever. There are actually quite a few sets of Gen 1’s flying that the owner of the plane decided the numbers achieved in destruction testing were more than sufficient and decided not to have the cap upgraded.

My phone number is 704-806-3582 or 704-906-8473 and I am more than willing to talk through any issues you may have or address any questions.
 
Back
Top