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AV8ORJWC
Joined: 13 Jul 2006
Posts: 1149
Location: Aurora, Oregon "Home of VANS"
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 Posted: Tue Jan 23, 2007 7:51 am Post subject: Van's Motor Mount SB Ranting |
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Allen, thank you for clarifying what should have been obvious to most
builders. Your engine is not a "clone". That statement presents the
voracity of contempt held at VANS to those renegade builders who have
the audacity to improve on a design.
Seems that was exactly how VAN started his business with an improvement
to someone else's design a few years ago which began this process of
model improvement. I have posed to Jon Delamarter that he might respond
on the Thunderbolt "Clone" products as well. Next we will hear that
unless you buy a new engine direct from VAN, then the mount will not
work. That you will fall out of the sky with a Lycoming Thunderbolt.
Or, we will again hear how flutter and speed are bringing down the
fleet. Another reason to check those lead counter-weights against the
written standard - additional weight with those clones engines.
Deems - thanks for the prompt response. Scott - thanks for doing the
right thing for Deems. Now to get the welder to do them right in the
first place. Tim, you must be running a clone as well, since it wasn't
and still isn't a Barrett and you seem to have done the unthinkable by
modification to the correct mount.
John Cox
#40600
Do not Archive as the logic of this post defies gravity.
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owl40188(at)yahoo.com
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| Posted: Tue Jan 23, 2007 10:07 am Post subject: Van's Motor Mount SB Ranting |
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I don't want to ruffle anyones feathers here, but here is a different point of view.
I had talked to Van's regarding the certified engines about 1 to 1.5 years ago. They did not try to just sell me a certified engine. In fact they told me that the I was better off getting an experimental engine from one of the engine builders. So my experience with Van's makes me believe that they are not out to just sell an engine; and of course they make money selling engines. The RV10's, RV9, RV7s and RV8 are selling well and I am sure Van is doing very well financially. Now a few crashes of RV10 due to supposedly structural problems could slow his sales down in a hurry so I think his viewpoint is based more on safety then selling engines.
As far as hot rodding, there is definitely an actual amount of power above which one might get in trouble if they don't modify the structure to handle it. Is that 260hp 300hp or 400hp it appears no one knows. Van's claims that it can handle 260 hp but they don't want to stick their neck out any further and I don't blame them for that. The 260hp number is what their design and testing is based on. Is there some margin? Probably, if not they cut it too close.
If its okay to go to 280hp is it okay to go to 300hp or 350hp how about 500hp? Where is the cutoff? Should the person going to 300hp have to do some homework to ensure that the aircraft will be safe with that much power? If the plane does come apart and people get killed than was he not negligent ? I can see having to defend this in court, "Are you a structural or aeronautical engineer? No. Have you designed any aircraft or have experience designing aircraft? No. Well then if the designer of the aircraft thought that it was not capable of handling more than 260 hp, and repeatedly said so, what made you think that you knew better?" and no I am not a lawyer. The bottom line to this is if you are going to modify it and fly it outside the envelope that Van's has designed it for than you need to do the analysis and/or testing to verify that its safe in the expanded envelope.
Lets go back to the fatigue discussions we had several times on this list. If there was a fatigue critical item in the engine compartment (i.e. engine mounts, engine mount support fittings aft of the firewall that are ending up with short edge distance in a lot of aircraft, etc) then going to 286 hp (10% increase) would halve the life of these items and at 315 hp you would have approximately only 1/4 of the life left. And maybe you allready ate away at half the life because your edge distances were to small. Now for someone going to 315 hp are you sure that those items are not critical?
Niko
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Jon A. Delamarter
Joined: 20 Jul 2006
Posts: 14
Location: Williamsport, PA
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| Posted: Tue Jan 23, 2007 10:46 am Post subject: Re: Van's Motor Mount SB Ranting |
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| AV8ORJWC wrote: | Allen, thank you for clarifying what should have been obvious to most
builders. Your engine is not a "clone".
I have posed to Jon Delamarter that he might respond
on the Thunderbolt "Clone" products as well. Next we will hear that
unless you buy a new engine direct from VAN, then the mount will not
work. That you will fall out of the sky with a Lycoming Thunderbolt.
John Cox
#40600
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If I am not mistaken, I believe that the core issue at the heart of this discussion really extends beyond liability concerns.
But first, let me back up Allen's statement regarding a "clone" Lycoming from BPA. A clone, in my opinion, would refer to a Superior or ECI engine. The folks at Barrett assemble their engines from a box of Lycoming parts that they buy from us, Lycoming. In other words, the majority of their parts come from the same parts bin as a certified or Thunderbolt Lycoming. As with all of our kit shops, they have the discretion to modify the parts or add parts that in their judgment are safe and suitable. Michael and a lot of other folks have bought engines from BPA based on a well deserved industry reputation.
Having said all that, I think it is just possible that the Van's SB specifically mentioned Monty's custom sump/intake system due to the fact that, to date, this is really the only commonly used aftermarket system of it's type (Tip of the hat to my good friend Kevin Murray at SkyDynamics; Kevin's system uses a stock Lycoming sump and is not exactly an equivalent.) Monty led the way in the experimental aftermarket with his system long before the RV-10 was on Van's drawing boards. And yes, to Michael's point, the cold-air system we are developing in Thunderbolt is similiar enough that I expect that the same interference would occur. (I must take a technical exception to one of your points, though Michael; a Barrett engine is not a stock Lycoming engine by definition. Neither is any engine that we build here in Thunderbolt. That's not a bad thing! It just means that those of us in the custom experimental engine market have an opportunity to do things a little differently.)
To Van's point, I understand their reticence to implicitly or tacitly endorse modifications of their design. Once that is allowed to begin, where does it end? The line simply must be drawn somewhere. We cannot in good conscience ask an engineer to design in a safety margin and then endorse our intention to disregard that margin. Again, to Michael's point, throttle/manifold pressure management is a legitimate method for limiting horsepower.
Now to the core issue I mentioned at the beginning. Those of us who participate in the experimental aircraft market do so knowing full well that the law supports the individual builder's right to modify the end product at will. Participation at any level is therefore risk inherent. Therefore, as a member of this group, I would ask that you would be patient with our attempts to balance innovation and performance with safety and reasonable risk.
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_________________
Jon A. Delamarter
Thunderbolt Manager
Lycoming Engines |
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rvbuilder(at)sausen.net
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| Posted: Tue Jan 23, 2007 11:22 am Post subject: Van's Motor Mount SB Ranting |
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In reality the 260HP number means next to nothing. The real limiting factors are in the size and weight of the engine, any changes that it causes to the CG, possible torque increases on the mount, and most importantly VNE. Van’s is stating that they believe that there is no chance to exceed their design limitations in normal flight with an engine rated at 260HP. I say rated because it is impossible to say if a engine is putting out more or less HP unless someone builds reference data for that engine using a known measurement like a dyno.
So that being said, if someone limits an engine of any size to the same characteristics they are not exceeding the design specifications. In the case of a larger engine, anyone can mitigate weight issues by doing a weight and balance. In my case the sump is lighter than the stock component. Torque, well that can be a bit of a guess as I’m betting Van never did any destructive testing on their mounts so they have no idea if there is a flaw in even the current version that could rear its ugly head down the road. But then again there is a fair amount of data at this point on the “stock” 540 in an RV-10 for us to take a good guess that there isn’t a problem. Most of us that are making improvements to the engine are doing it to the exact same 260HP Lycoming IO-540 that is considered acceptable so let’s just assume the mount is perfectly fine for this application. That leaves us with the VNE issue. There are plenty of ways to exceed VNE with a stock 260HP engine. If you cross the manufactures set VNE limit you have moved into the test pilot realm and you are on your own. Hopefully you know what you are doing. If the modifications to my engine put me over 300HP (they didn’t) it makes absolutely no difference to the aircraft as long as the other parameters are kept in check. Easiest way to do that is by connecting your eyes watching your airspeed with the hand controlling the throttle.
So my point is I don’t feel it’s an actual amount of power expressed in HP that is the issue as that really has no direct bearing on if you will fall out of the sky. So if that number is really irrelevant as long as you keep things inside the design boundaries, who cares what the actual HP number is? Operating limits are valid numbers and also something Van should absolutely stand behind but I would rather see those than just saying arbitrarily that anything over 260HP is going to be a problem.
It’s Van’s choice on whether or not to accommodate the builders out there and Barrett’s cold air induction is a popular option. As I told Scott, I understand their decision even if I don’t agree with it. Allen immediately had a solution to the problem so I’m not concerned. You can also bet that Thunderbolt is going to be pushing their cold air induction from Lycoming and they will see the same problem. Will Van’s have the same stance on the subject even though it is a direct Lycoming option? Maybe Van’s will silently change the mount design under the guise of optimization once this subject dies out a bit so they can say they didn’t do it for the hot rodders out there. Time will tell. In the mean time Scott has agreed to drop ship my mount directly to Barrett for his local man to modify. I’m glad to see they are willing to work to a compromise with some of us on this. If anyone else is ordering an engine with cold air, make sure you add this request to the finish kit order. Once I have it back I’ll be happy to post pictures. Interesting thing is that I’ve been told the first several kits didn’t even have the troublesome cross member in the engine mount and haven’t been replaced.
Michael
From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Niko
Sent: Tuesday, January 23, 2007 12:07 PM
To: rv10-list(at)matronics.com
Subject: Re: Van's Motor Mount SB Ranting
I don't want to ruffle anyones feathers here, but here is a different point of view.
I had talked to Van's regarding the certified engines about 1 to 1.5 years ago. They did not try to just sell me a certified engine. In fact they told me that the I was better off getting an experimental engine from one of the engine builders. So my experience with Van's makes me believe that they are not out to just sell an engine; and of course they make money selling engines. The RV10's, RV9, RV7s and RV8 are selling well and I am sure Van is doing very well financially. Now a few crashes of RV10 due to supposedly structural problems could slow his sales down in a hurry so I think his viewpoint is based more on safety then selling engines.
As far as hot rodding, there is definitely an actual amount of power above which one might get in trouble if they don't modify the structure to handle it. Is that 260hp 300hp or 400hp it appears no one knows. Van's claims that it can handle 260 hp but they don't want to stick their neck out any further and I don't blame them for that. The 260hp number is what their design and testing is based on. Is there some margin? Probably, if not they cut it too close.
If its okay to go to 280hp is it okay to go to 300hp or 350hp how about 500hp? Where is the cutoff? Should the person going to 300hp have to do some homework to ensure that the aircraft will be safe with that much power? If the plane does come apart and people get killed than was he not negligent ? I can see having to defend this in court, "Are you a structural or aeronautical engineer? No. Have you designed any aircraft or have experience designing aircraft? No. Well then if the designer of the aircraft thought that it was not capable of handling more than 260 hp, and repeatedly said so, what made you think that you knew better?" and no I am not a lawyer. The bottom line to this is if you are going to modify it and fly it outside the envelope that Van's has designed it for than you need to do the analysis and/or testing to verify that its safe in the expanded envelope.
Lets go back to the fatigue discussions we had several times on this list. If there was a fatigue critical item in the engine compartment (i.e. engine mounts, engine mount support fittings aft of the firewall that are ending up with short edge distance in a lot of aircraft, etc) then going to 286 hp (10% increase) would halve the life of these items and at 315 hp you would have approximately only 1/4 of the life left. And maybe you allready ate away at half the life because your edge distances were to small. Now for someone going to 315 hp are you sure that those items are not critical?
Niko
[quote] [b]
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