Is it possible to build Part 103 legal LE XL with 20lbf heavier engine?

[wojtekseta]

Les Homan has a thread here somewhere that contained a weight list of various parts. It had the weights you're looking for. A search may pull it up.

I'm with you on the latex. Doing the same here.

I found it! ( https://www.eaglersnest.com/forum/index.php?topic=155.msg547#msg547 ) This is really what I was looking for. Thank you very much, Dave. BlackMax are lighter than I thought, but with BMX wheels I should save about 8-10lbf .

[wojtekseta]

Many years ago I built a SkyPup and used dacron fabric from the local fabric store. Dirt cheap and it worked fine. It's the stuff you'd line a suit jacket with. Easy to work with, glue and shrink. Lots's of area to glue the wing fabric too. The ribs were 3/4" thick styrofoam.

A buddy of mine recently covered a Tailwind with the Stewart system fabric and used the latex process and it went well.

I tried to find the other dacron, but didn't found. Price of noncertified dacron in aircraftspruce.eu is acceptable (~$6/yd) - i'll buy from them, as some other materials.

[Tom XL-7]

How about $4.35/yard

http://www.aircraftspruce.com/catalog/cmpages/peelply3.php?clickkey=5724

search under dacron or peel ply if you don't find it listed as covering.
It is not perfect, may have some slight blemishes.

Sometimes the fabric store dacron is pre-shrunk, 
while an advantage for clothing,
a disaster for our use.

[wojtekseta]

Tom - I know, but it is in the USA. In Europe I will buy http://www.aircraftspruce.eu/dacron-fabric-1-8-oz-x-60--611.htm . I think it is the same fabric, but for the other price
Once I bought 4130 tubing for samples, welding training and load tests from aircraftspruce.eu . Prices was very high ( FIVE !!! times higher, than metric tubing from 25CrMo4, which is exact european analog of 4130). I thought I will receive american tubing, but when I read on them "Made in Germany" i called to AS.EU. They said, that they import german steel from the USA. Aircraftspruce.eu is located in centre of Germany.
I think the Dacron could be "Made in Europe" to ...

[wojtekseta]

I'm trying to estimate the impact of a heavier engine on location of the CG. I looked to my set of plans and found, in my opinion, incosistency between sheets C, D and description on text page 11 ( empty weight + pilot 255 lbs or 275 lbs , with or w/o gas and oil ). For example: from sheet C empty weight = 246, from sheet D pilot = 255 (in text decription 275), gas = 30, oil = 4 and sumary is 507 lbs. Maybe I'm wrong or I omitted info about corrections? Could you tell me please, was it discussed on the forum?

[Dave Stroud]

It seems we have to try harder and harder to find the true source of our supplies. Before ordering my 4130 from Aircraft Spruce Canada, I got a very favourable quote from a steel supplier in Pennsylvania and he said it was genuine made in Germany. The price was about 85% of ACS. In Europe, I would try to source direct from Germany or equivalent.

[wojtekseta]

It seems we have to try harder and harder to find the true source of our supplies. Before ordering my 4130 from Aircraft Spruce Canada, I got a very favourable quote from a steel supplier in Pennsylvania and he said it was genuine made in Germany. The price was about 85% of ACS. In Europe, I would try to source direct from Germany or equivalent.

I can't find the source of imperial 4130 tubing in resonable prices in Europe. If I will build, I will build from metric 25CrMo4 tubing. It will cost about 3 lbs heavier fuselage.

[ArcticDave]

The bulk of 4130 I bought from Aircraft Spruce was German. The rest was Promoly from Plymouth here in the States. 
The German stuff is stamped "Benteler" and it appears to be the name of the manufacturer.

[wojtekseta]

I can make some conclusions. Teoretically the answer to the question of the subject is Yes.
Some savings allow me to remain within the limit of 115 kg, but the margin for deviations from the plans is small. With R1200 in place of BetterHalf CG should be about 25% of the chord, what Leonard somewhere described as "good start point" , but XL flying collegues write that best CG is at 28-30%. To do that I have to move the wing 2 inches forward, or put 7lbs ballast on the tail.

Excel with wieghts and CG.

[Dave Stroud]

Do you know how much thrust the BMW will produce ?

[wojtekseta]

Do you know how much thrust the BMW will produce ?

I have not finished my tests yet ( https://www.eaglersnest.com/forum/index.php?topic=1525.0 ). From charts looks like R1200 should turn to 3600 rpm similar propeller as 4 cylinder VW1600 and should produce similar thrust. At this point it have about 40kW = 53HP. I belive, when you tune the engine to work at this point, it could be even more. But for LE XL I plan to use heavier propeller, which limit rpm to 3200-3300 (45HP) because of endurance reasons. My fuse will be only 10 - 15% stronger than built per plans. I hope the balancing shaft will prevent vibrations in this rpm range. In previous versions of BMW boxers it could be a problem.
One thing we have to remember, BMW is spinning in the opposite direction than front drive VW. You should use propeller for flywheel side drive.