Did an initial Mount of the 107 Hp Ul Power Engine and attached the Empennage
http://imageshack.us/photo/my-images/821/ulpowerengine004.jpg/
http://imageshack.us/photo/my-images/821/ulpowerengine004.jpg/
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Imageshack sucks - loads of pop up ads. I found it really difficult to view the pictures ...
Just Attached the 2 fuel pumps and prefilters to the firwall.
Modified the Rotax Oil Tank and Batttery box.
https://picasaweb.google.com/111690756223683866568/January282012#
Since the advertised weight of a complete engine installation is very similar to the installed weight of a Rotax 912, why do you have the engine mounted what looks to be about 12" further fwd, than the Rotax mounts?
I really wouldn't be putting my fuel pumps there..i.e on the hot side of the firewall sucking uphill.
This is is significantly increasing the chances of vapour lock, especially running mogas. Might be OK but why risk it?
Best to put them in the "hydralically correct location"..I.e at the low point of the system in as cold of a place as possible.
Short dissertation.. Fuel is a high vapour pressure liquid. When the suction pressure (suck of the fuel pump) exceeds the vapour pressure the fuel will boil. The pump cannot pump vapour, or at least not very well. Most suck is at max flow, i,e full throttle. Hot fuel has a higher vapou pressure than cold fuel.
In other words when you drop the hammer on a really hot day with your recently flown heat soaked engine, you might find the engine quits on take off.
Frank
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 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.
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.
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.
This aircraft is in the making. It is not finished.
The inputs positive and negative are considered with an open mind.
I am aware of the robustness of the firewall attachment points and the unique challenges the design presents.
We will address the long term serviceability of the installation.
It is interesting that while we have almost exactly the same CG as the 85 HP Jabiru installation, I have not seen the concerns mentioned in this thread.
The initial W&B was done with every item to include the seat cushions.
The next time we do a W&B I will include a picture and a list of the equipment.
Please keep the comments, observations and advice coming as I value each and everyone.
My RV-12 has an empty CG of 80.97" with autopilot, and no paint. The UL engine could be moved aft approximately 5" to move the aircraft CG 1" aft. I based that approximation on calculations done by an Excel spreadsheet. If anyone is interested in downloading this Excel spreadsheet for calculating weight and balance of their RV-12, see this post: http://www.vansairforce.com/community/showpost.php?p=481088&postcount=4The empty CG is calculated at about 80 inches with all available items less any fuel.
We have done an initial mounting of the engine on a first generation mount.
We will be weighing the RV this week to to verify the installation.
It appears that we may be able to move the engine 6" to 8" closer to the firewall, if so we may be able to adapt the Rotax Supplied Cowl.
We had ordered the materials lasr week.
I just received the materials to construct a modified Mount that
is 5 1/4" shorter than the initially designed mount.
We will report the results when available.
Regards
Battery is located in the tail cone
Quote
Rahul
The 3300 has a shorter engine mount placing the intake close to the firewall. Also the Battery is located in the tail cone to correct the weight and balance.Will wait to do final weight and balance when the cowl is on and it is painted. I also have servos and wheelpants that will also help the W&B.