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Old 08-11-2019, 05:34 PM
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Moving Engine for CG Setup

Hi,

I would like to move a DLE35RA engine a millimeter or so to move the CG of a plane forward. Is it ok to use washers between the engine and standoffs, or between standoffs and firewall?

Thanks,

David
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Old 08-11-2019, 06:25 PM
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wrongwayfeldman
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Yes. ....I do it all the time...just be sure to use 4 identical washers or it can change the thrust angle.
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Old 08-12-2019, 12:14 AM
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The critical part is to make sure you have enough threads left to not strip them. You want at the very least thread depth equal to the bolt diameter and that's far from ideal in aluminum, but it will give you a reference point on thread depth. Feel free to stack washers, drilled wood, etc - but leave enough bolt threads into the mount/engine to not cause issues. Even following my own suggestion I mildly pancaked a 35cc plane and popped all 4 bolts out of the engine causing carb damage due to linkage keeping the engine in place. Inverted harrier, stiff fuel clunk starving it, 10 ft of altitude to roll upright. It wasn't pretty. I know, too much info. But it was funny at the time.
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Old 08-12-2019, 08:36 AM
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Thank you guys.

KMatch, sorry for that incident.

Is there any difference (besides the obvious) stacking between engine and standoffs or between standoffs and firewall?
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Old 08-12-2019, 09:54 AM
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No difference really. It's just another spacer of solid material and more solid than the wood it's attached to. For CG, you might as well make the spacers heavy and focus them more forward. Just don't expect a lot of cg change without a good bit of movement. 1/4" at a time of engine movement results in subtle changes.
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Old 08-12-2019, 10:17 AM
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Thanks for that information.

I’ll posts the results.
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Old 08-12-2019, 05:39 PM
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You can find various length spacers also from McMaster & Carr which can be used with through bolts. Just an FYI
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Old 08-12-2019, 09:18 PM
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JTec offers laser cut spacers. I’ve used them on several planes. They will cut to most motors and offer various thickness. It’s a great way to fine tune spinner gap.
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