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Oct 04, 2017, 07:52 AM
Registered User
Build Log

learjet 45


hi all

this will be a very long build log starting from the very good Rudis Micro learjet plans. I have no free time and I can work on this project only few hours a week.

My learjet will have the following characteristics:

wing span: 2000mm (more or less)
2 edf units (64mm)
weight: Really I don't know but below 2000gr; I'll let you know better when the design will be in a more advanced phase

The construction is a mix among depron (6mm), carbon rods and 3D printed parts.
Ribs, fuselage formers and some other internal parts in PLA.
Fuselage and wings are then covered by 6mm depron.

Is there anybody who tested a very good glue for depron and PLA parts?

Of course any comment will be very appreciated

Here a first look of the fuselage skeleton
Last edited by rl70; Oct 17, 2017 at 07:41 AM.
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Oct 04, 2017, 08:26 AM
Give me a TriStar anyday!
NAKIAM949's Avatar
Great build idea, this is one of my favorites I'm definitely subbed here's a good representation of the Learjet, an older model
but still could be helpful in some aspects.
Oct 04, 2017, 05:05 PM
Up-Out-&-Gone
demondriver's Avatar
This is gonna be a great build RL!

foam safe CA, UHO and 5min epoxy are great glues for depron.
Latest blog entry: My RC 737 Assembly line!
Oct 05, 2017, 03:47 AM
Registered User
Rudi's Avatar
Hi rl

I will follow your project very close. Let me correct one thing. I have not drawn the plan. It was Philippe Jamet (GGRN). I only build it in two sizes and I uploaded the plan to the net with Philippes confirmation.

Here is little motivation for you. This is the remaiden video of my bigger LJ-31(with retracts)

BigLJ51 with retract mod (3 min 1 sec)


best

Rudi
Oct 06, 2017, 12:28 AM
Registered User
Thanks guy

Rudi, sorry for my mistake
Oct 06, 2017, 04:49 AM
Registered User
Rudi's Avatar
Quote:
Originally Posted by rl70
Thanks guy

Rudi, sorry for my mistake
rl, no need to excuse. I only wanted to spot the light on Philippe and not on me.

good luck

best

Rudi
Oct 17, 2017, 07:40 AM
Registered User

more progress


A little progress. I started designing the edf support (the EDF is a 64mm unit). review the image. It has to be completed and (of course) lightened

until now SOLIDWORKS design is around 350 gr
Oct 17, 2017, 09:54 AM
Registered User
jumo004's Avatar
VERY interesting construction !!!

Looking forward to more screen shots.
Oct 17, 2017, 05:14 PM
Up-Out-&-Gone
demondriver's Avatar
Quote:
Originally Posted by jumo004
VERY interesting construction !!!

Looking forward to more screen shots.
+1 on that!

R170, what are your learjet's internal Fuselage frames and cross sections to be made from?
Latest blog entry: My RC 737 Assembly line!
Oct 18, 2017, 07:17 AM
Registered User
hi demondriver

they will be PLA or ABS (3D printed); the rods are carbon rods
Oct 18, 2017, 08:28 AM
Up-Out-&-Gone
demondriver's Avatar
Quote:
Originally Posted by rl70
hi demondriver

they will be PLA or ABS (3D printed); the rods are carbon rods
ABS should be strong enough for what your doing.
Latest blog entry: My RC 737 Assembly line!
Oct 18, 2017, 09:57 AM
Ninja Master
BigSwede's Avatar
Haha, I'm designing a CRJ 700 with nearly identical construction. 3D printed formers, nacelles and some other parts, carbon tube longerons, some molded fiberglass parts. Still in early design process and with two little kids I'm not making a whole lot of progress on it. I'll be following your build, it's looking good.
Oct 25, 2017, 07:17 AM
Registered User
Bigswede

have you got a thread about it?
I'm interesting in following your design, too

I'm in a similar situation (two kids, 9 and 12) who require my free time for homeworks when i'm back home
Oct 25, 2017, 07:29 AM
Registered User

servos' positions


Hi

two questions for the "better than me" scratchbuilders:

1) servos for elevators and directional are planned to be positioned as in the attached picture and will be 9gr servos (metal geared or not?); are OK?
2) any downtrust, uptrust, left or right trust for the edfs?

waiting for your very important feedbacks
Oct 25, 2017, 05:27 PM
Registered User
AntiArf's Avatar
Until I start breaking servos, the metal geared servos come with a weight penalty, for their added assurance over lighter nylon and composite geared servos, which have been working well for years. Tail mounted, they're even more of a penalty, where the battery in a Lear jet will probably have to be quite far forward to offset the weight, to avoid ballast. It's worth considering a bellcrank linkage for the elevators, as they will have to be driven individually, due to the tail sweep. Built a few recently that worked out well. On a larger model, the white plastic bushings on either side of the linkage rod below, would need to be a bit more robust (such as collars) to keep the linkage slop free.
https://www.rcgroups.com/forums/show...5&postcount=35
https://www.rcgroups.com/forums/show...3&postcount=11
The TU 104 setup I'm using now was derived from the hidden linkage aileron system, which is fully hidden and even better.
https://www.rcgroups.com/forums/show...6&postcount=17
https://www.rcgroups.com/forums/show...8&postcount=23

I used pretty much scale settings, with more or less 0-0 wing-stab incidence, and up thrust angle as close as possible to the full scale. I noted where Dave Ramsey has stated that he had a nose low situation with added throttle, likely due to added positive wing incidence. I didn't have that issue and the model trimmed well.


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