REFLECTOR: Thrustline change

[Carl Hoffman]

On Mar 31, 2013, at 10:36 PM, "David Ullman" <ullman at robustdecisions.com> wrote:

> Thanks for all the feedback.  Based on it, I am going to make two changes:
> 1. change the thrust line.  I will start with about a 1/4 inch and see what
> I learn.  I will report back.
> 2. Raise the nose about an inch.  Right now when I takeoff with just me on
> board and about 1" of elevator down trim , I get to about70kts and still
> have to pull back, then pop off the runway.  The pop is dramatic enough that
> I warn passengers before the TO roll. I can change the setting on the nose
> wheel (Fixed gear) with a spacer behind the rubber block  (the new verison
> of rubber).  Not easy to get to, but changeable.  It will be interesting to
> see if this also affects shimmy.  I don't have much now, but this will
> change the castor angle.
> 
> I expect these two changes to shorten my take off roll.  Stay tuned.
> 
> ON another topic.  I wrote a few weeks ago that I was throwing a lot of oil
> out the breather.  I took the advice of some and ran the engine for a couple
> of hours wide open.  Believe it or not, it worked!!!  My prop and belly are

What RPM did you run it at for a couple of hours?

> no longer oil coated when I land.  There is a little, but an order less than
> there was.  I have had two flights now with minimal oil loss.  Amazing!!!
> 
> David Ullman
> N444DX
> President EAA 292
> 541-760-2338
> david at davidullman.com
> 
> 
> -----Original Message-----
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> Today's Topics:
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>   1. Re:  Thrustline change (dennis.doc)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Sun, 31 Mar 2013 10:58:08 -0600
> From: "dennis.doc" <dennis.doc at gmail.com>
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Subject: Re: REFLECTOR: Thrustline change
> Message-ID:
>    <CAG8_WT8Mmfj2nwbn7HY35LRG7q7Kdatc1KjRwUq_uoX76VYezw at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> I added over one inch of shim to my engine mount. I called Scott Swing to
> make sure it would be OK. He told me "no problem." He and a local friend
> said there are advantages in take off and landing (more downward thrust)
> and that I could change it later if it  proved ineffective. I'm still
> flying off the 40 hours, but in the 10+ hours I've flown, no perceivable
> problems. I do notice that in cruise, while trimming the elevator 100% down
> - the trailing edge remains virtually neutral.
> 
> Dennis Martin
> 
> 
> On Fri, Mar 29, 2013 at 11:29 AM, David Ullman
> <ullman at robustdecisions.com>wrote:
> 
>> When I cruise with only me in the SEFG I have to put in 1/2 inch of down
>> trim (elevator up) or more.  This is clearly inefficient.  I already have
>> 18lb of lead in the nose and don't want to add more.  A friend suggested
>> shimming the top of the engine mount for a little downward pitch moment.
> I
>> sort of like the idea but am worried that it might increase my take off
>> distance as it will drive the canard downward a little.  He thinks it may
>> help as the engine thrust line is slight more upward.
>> 
>> Any thoughts or experiences?
>> 
>> 
>> David Ullman
>> N444DX
>> President EAA 292
>> 541-760-2338
>> david at davidullman.com
>> 
>> 
>> 
>> 
>> 
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