Online Community of Zenith Builders and Flyers
For some of us scratch builders, welding an engine mount is as simple as the top of the fuselage and controls. Unfortunately it seems like there is no plans for the UL 350 either in the cruzer, STOL or options drawing (have all 3)
Now I have bee told by Michael that the UL power and Jaribu 3300 share the exact same engine mount. Plan JE-1 of the options drawing package.
But that is where my problems start!
1) - Jaribu 3300 and UL have different engine mounting points (250 x 249) Ul is (250 x 260) needless to say that will not fit, also the Y spacing is different UL would sit 15 mm lower on the thrust line ... 95 mm vs 110 mm. BTW the Jaribu 2200 has (250 x 260) still the 701 firewall is much smaller so it wouldn't fit a 750
2 ) - Clearly looking at side view pictures the UL and Jaribu 3300 have different measurments from the firewall (CAD scaled using mounting plate to spindle) 470 mm UL and 529 mm Jaribu according to the OEM manuals (engines have different lengths) mount of the UL power is clearly longer that the one for the 3300
and tubing isn't even similar...
3) - Zenith's plans call for 242 mm from the bottom of the firewall to the engine mount plate,and thats not even half length of the mount they sell for the UL in the FWF kits ! I'm confused
4) - Reverse engineering, moments N.m , center of mass of the engines, guessing, I get this below and that's not even close . I should not have to do this, clearly I'm missing something or I'm not in possession of all the info, after all the 750 is a rivet together kit !
Here's my request to this forum, can anyone with a UL 350 and a 750 look at their mount and give a yay or nay or even better a few measurements so I can double check that the plans are OK or not and build a mount that will not make my plane tail heavy ? So far I have not been able to get a response from Zenith after multiple requests ;-( Did Michael mean UL and a 2200 Jaribu ? still how would a 701 and 750 have the same firewall mounting points. If its a company secret and I'm forced to buy it finished from them I'd like to know also !
I don't think anyone has ever built a UL engine mount so this is probably the first they hear about this.
Thanks for any comments or help.
Hopefully I can make my JIG soon and get on with my project.
Jacques, I have my cowlings off doing a 50 hr service. Tomorrow I can obtain that measurement you are trying to verify, i.e.; the distance from firewall lower edge to engine mount plate you have shown as 242mm As an additional data point for you, the angular offset of thrust line to longitudinal line is 3 degrees per Caleb (former Aero Engineer with Zenith). HTH
David, that's great news! Thanks so much for your help.ok so 3 degree would be the same as on the 3300 mount. Do you know if the offset to the left is 28 mm also?
If you have time also the easiest way to get it modeled in 3d would be to measure from the firewall bolt to the engine mount point (all 4 mounts to their closet firewall bolt, along the tubes. It will make a half pyramid shape...
, how do you like the 350 after 50 hours on it?
Keep in touch :)
Hi Jacques, sent you some dimensions. Not sure of left offset you are referring to or how to obtain that measure. So far the UL is doing fine, but a summer of full use should let me say more about it! It is very nice to not worry about mixture or carb heat. Starts the same, hot or cold OAT or engine temp. Averaging 4 gals/hr fuel burn using 93 autofuel with 10% ethanol. Just switched to a racing synthetic oil - Amsoil Dominator 15W-50W to see how it does with oil temps. CHT's run rather cool 240 plus or minus 15. Likely too cool to burn off any lead deposits if you plan on using 100LL, and I don't plan on using any unless I mix it on rare occasion with unleaded fuel. Good luck with your project, with your talent and expertise it's going to be great homebuilt product!!
Last thought Jacques...try calling Roger or Steve at Zenith in Mexico MO. I believe they would provide any dimensions you need for scratch building that UL engine mount. The UL rep (Robert Helms) should be able to help as well.
Im looking forward to getting that engine also, 4 gal per hour is very good!
For the offset I'll use the same as the jaribu, no idea how to measure it but I'll be able to extrapolate a value with the dimensions you sent me :)
Keep us posted on the 350, first hand account of a pilot is very useful for us considering using it in the future
Do you have documentation showing how the ul350 is offset a couple of inches left of aircraft centre line?