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  #31  
Old 01-29-2012, 05:48 PM
Alschief Alschief is offline
 
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Default Fuel line Pictures

A few more photos of fuel routing.

https://picasaweb.google.com/1116907...eat=directlink
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  #32  
Old 01-29-2012, 06:07 PM
Peterk Peterk is offline
 
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Default Very Cool

I think what you are doing is very cool and applaud you for posting pictures of your install. Posting pictures of a unique approach in the land of experts is just asking for "wisdom." dag-nabit...you had two "uh-oh's" within an hour of your pictures finally making it to the forum. Too funny. Designers don't like experimenting unless they are the experimenter. You have managed to get past all of that and deserve to be recognized. A true experimental aircraft...good job.

Last edited by Peterk : 01-29-2012 at 06:08 PM. Reason: changed **** to dag-nabit
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  #33  
Old 01-29-2012, 06:34 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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Quote:
Originally Posted by Alschief View Post
It would seem that he Rotax may be a little heavier than the UL or Jabiru engines.
The total empty weight was 695 lbs as weighted during thw intial W&B.
The empty CG is calculated at about 80 inches with all available items less any fuel. Full fuel and one pilot we caluculate a CG at about the 82" range
We may be able to shortening the mount approximately 5"to move the CG slightly more aft, this possibility this is being considered.
We have the materials on hand.

UL Power Table of Weights for reference:

Weight of basic standard engine and accessories
Dry weight of the basic standard engine from serial production:........................60,1 kg (132,5 lb)
The total operational weight depends on the accessories installed. Typical accessories provided by
ULPower have the following weight:


Possible fully operational engine weight for the UL260iSA:.................................75 kg (165,3 lb)
I guess it all depends on how complete the airplane was when you did the initial weighing.
A basic RV-12 built per plans, and equipped with the standard seat cushions, but no exterior paint will weigh 720 lbs (give or take a pound or so).

I believe the RV-12 engine installation weighs in at 165 -170 lbs. That makes it very similar to the Jab. and the UL. If your initial weighing configuration was still lacking some finish details, a couple pounds here and a couple there can add up to another 20 pounds real quick. If that ends up being the case, to my eye your engine looks way to far forward (but actual numbers derived from weighing on reliable scales will be the real proof).

As a secondary note.... I am concerned that you are still using the original engine mount attach points with the engine cantilevered a long ways ahead of the fire wall, but apparently no change to the structure in the fwd fuselage? It appears you have done a good job of triangulating the engine mount so it will probably not be an issue with an engine of this weight. Where my concern lies is that you have greatly increased the moment of the engine loads that transfer into the fwd fuselage. It is my opinion, that if you repeat the landing gear drop tests that were required for ASTM certification (which were all passed by an RV-12 using the Rotax engine configuration), the greatly increased moment arm of the engine would likely result in a failure of the fwd fuselage and nose gear.
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  #34  
Old 01-29-2012, 06:46 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by Peterk View Post
I think what you are doing is very cool and applaud you for posting pictures of your install. Posting pictures of a unique approach in the land of experts is just asking for "wisdom." dag-nabit...you had two "uh-oh's" within an hour of your pictures finally making it to the forum. Too funny. Designers don't like experimenting unless they are the experimenter. You have managed to get past all of that and deserve to be recognized. A true experimental aircraft...good job.
So, I guess you are thinking that any one nuts enough to be building an airplane in their garage (we probably all fit that category), should be able to do what ever they want while only receiving back slaps and high fives? Even if other people see things that they think might be an issue?

Sorry Peter, I can't do that. Especially, if I think others may blindly follow in their foot steps. To be fare, keep in mind that I try and remain open to others opinions regarding my work, and openly seek out others to inspect critical maintenance or design work that I complete.

In my opinion, if someone is going to post photos or ideas in these forums, they should be doing so for the input that is available, not just for a slap on the back.
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  #35  
Old 01-29-2012, 07:29 PM
Peterk Peterk is offline
 
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Quote:
Originally Posted by rvbuilder2002 View Post
So, I guess you are thinking that any one nuts enough to be building an airplane in their garage (we probably all fit that category), should be able to do what ever they want while only receiving back slaps and high fives? Even if other people see things that they think might be an issue?

Sorry Peter, I can't do that. Especially, if I think others may blindly follow in their foot steps. To be fare, keep in mind that I try and remain open to others opinions regarding my work, and openly seek out others to inspect critical maintenance or design work that I complete.

In my opinion, if someone is going to post photos or ideas in these forums, they should be doing so for the input that is available, not just for a slap on the back.
My comments were sincere Scott. This is an unusual situation and deserves a shot of confidence. If for no other reason, to encourage others to experiment yes, but even more so to post their efforts in front of everyone and welcome input. (few will go there!) Your comments can be very helpful to his adventure I'm sure. You have given me helpful assistance.

And yes, all of our comments should be directed from a point of encouragement even if he does want to build a secret deathtrap in his garage. If we don't, he will only build kits or worse yet...hire someone to build one for him/her. (48% of EAB accidents are purchased?)

Yes, its obvious the engine mount length is an eye-catcher. If it isn't going to work its going to fail a CG calculation or an airworthiness exam (or should!). I do applaud his sticking his neck out and you yours (you just can't bring yourself to butt out and that's a good thing too). But as you know, the critiques in here can be viscous and without thick skin like ours that confident experiment will be dead in a week.

Pete

Just wanted to give the man some balance instead of just the things he's doing wrong. I want to see him succeed...so do you.
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  #36  
Old 01-29-2012, 07:40 PM
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Geico266 Geico266 is offline
 
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Scott, I am glad you brought up the weight and balance. The plane certainly does not look compete enough for a W&B. The engine mount is very concerning to the eye. Hopefully, the op will take the care nessessary and have a few technical eyes looking over his shoulder as the engine mounting "system" is developed and proper W&B is achieved.
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Last edited by Geico266 : 01-29-2012 at 08:17 PM.
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  #37  
Old 01-29-2012, 07:50 PM
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MartySantic MartySantic is offline
 
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Quote:
Originally Posted by Geico266 View Post
Scott, I am glad you brought up the weight and balance. The plane certainly does not look compete enough for a W&B. The engine mount is very concerning to the eye. Hopefully, the op will take tthe care nessessary and have a few technical eyes looking over his shoulder.
Weight and balance considerations (which are easily remedied) is only one item that must be considered with the suggested mount. The forces that act on each of the engine mount anchor points must be looked at in detail to ensure the mounting locations are strong enough to withstand the expected loads. The forces will be very different with this mount.
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  #38  
Old 01-29-2012, 08:23 PM
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Geico266 Geico266 is offline
 
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Quote:
Originally Posted by MartySantic View Post
Weight and balance considerations (which are easily remedied) is only one item that must be considered with the suggested mount. The forces that act on each of the engine mount anchor points must be looked at in detail to ensure the mounting locations are strong enough to withstand the expected loads. The forces will be very different with this mount.
Agreed.
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  #39  
Old 01-29-2012, 08:55 PM
dick seiders dick seiders is offline
 
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Default

Just had to post my reaction to the engine mount pics. Don't know much about design loading, but that's (the engine) a long way out there. Why are the supports not made of tubing about twice the size normally used? Seems to me there would be considerable tendency for the mount to have a bit of twist and deflection in it under full power not to mention the concerns over pulling a few g's. Just sayin, be careful.
Dick Seiders
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  #40  
Old 01-29-2012, 09:22 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by Peterk View Post

Yes, its obvious the engine mount length is an eye-catcher. If it isn't going to work its going to fail a CG calculation or an airworthiness exam (or should!).
That is part of the problem with modifications.
It is not an inspectors (DAR or FAA) job to make a determination of whether an airplane design or modification is safe. They are only to confirm that the construction meets standard practices, and that they issue operating limitations that will protect the rest of humanity from you and your experiment.
I hope no one ever makes modifications with a hope that at final inspection, they will be saved from serious mistakes. They might, because a good inspector will probably voice their concern, but no one should bet their life on it

Quote:
Originally Posted by Peterk View Post
I do applaud his sticking his neck out and you yours (you just can't bring yourself to butt out and that's a good thing too). But as you know, the critiques in here can be viscous and without thick skin like ours that confident experiment will be dead in a week.

Pete

Just wanted to give the man some balance instead of just the things he's doing wrong. I want to see him succeed...so do you.
I do hope he succeeds... I never mean to discourage innovation. That is what got us to where we are today. But I will always emphasize that when you get into modifications of this magnitude (this is far from changing a cowling shape or adding a fairing for drag reduction) their are often other design factors that get overlooked, and I will point out issues if they concern me enough.
I personally witnessed RV-12 landing gear drop tests. Based on that experience, this concerns me.

I have said before... to minimize weight, and maximize payload, the RV-12 was designed structurally to the bare minimum needed (probably more so than any other RV model because of the pre-dictated max. gross weight). For this reason, any modifications that effect any load bearing portion of the airframe should be done with great care.

I have said my piece... you can now consider me Butt'ed out.

Last edited by rvbuilder2002 : 01-29-2012 at 09:25 PM.
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