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Hot Topic (More than 10 Replies) Jetstream from an original Midwest kit (Read 224 times)
staubkorb
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Re: Jetstream from an original Midwest kit
Reply #17 - Apr 6th, 2021 at 7:35am
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A little more progress.

I also found a reasonably priced electronic timer that uses a servo for actuation (servo not included) that I will be ordering.  AUW of the DT system (timer, servo and battery) is about 11 grams, so there is no weight penalty.  The glider will need approx. 25 grams in the snout anyway, so lead will still be necessary.
  

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staubkorb
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Re: Jetstream from an original Midwest kit
Reply #16 - Apr 3rd, 2021 at 11:33am
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Stab is ready for covering and the main panel (center) for the wing is slotted - ribs being glued in (drying) while writing this.

It's a good thing that I double-checked the rib spacing, as the tips have a narrower spacing than the center panel.  Normally, as in logical practice, rib spacing toward the tips would be either the same as the rest or progressively wider - not the other way around.  Lower mass toward the tips is better to allow quicker reaction to air currents and faster recovery from upsets.  I will, however, keep things original.  I MAY lighten the vertical stab, depending on the final weight of the model (from what I understand of the International A1 Postal, there is NO minimum weight).
  

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staubkorb
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Re: Jetstream from an original Midwest kit
Reply #15 - Apr 1st, 2021 at 5:20am
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Stab is built, needing only sanding of the tips and covering.  Cutting the slots for the ribs in the TE was relatively easy using my stringer slotting tool and a spacer - just a bit more work than the adjustable setup I have on my table saw (that I can't get to at the moment due to the clutter).

I had some reservations with the leading edge sheeting in that it is very stiff wood, but the curvature of the ribs was /is not too great and came out OK.
  

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Sky9pilot
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Re: Jetstream from an original Midwest kit
Reply #14 - Mar 30th, 2021 at 12:03pm
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A builder with your skills will have no problem whipping up an interim tool/jig that will fit the bill!
I look forward to your solution.
  

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staubkorb
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Re: Jetstream from an original Midwest kit
Reply #13 - Mar 30th, 2021 at 4:58am
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Have to notch the trailing edge strips - another item that was improved with later kits.  No big deal, but to do accurately, one should set up some kind of jig to get the spacing right and also the proper depth.

My "tool room" is still too cluttered from the time my Son and his wife (and two CATS) were living here, so getting to the tools needed is practically impossible...

Working on it...
  

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Re: Jetstream from an original Midwest kit
Reply #12 - Mar 29th, 2021 at 1:21pm
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At least you've got timers. I hear you about the cost of the electric devices.  Lots of things above my price limit!

Looking forward to your next post!
  

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And ye shall know the truth, and the truth shall set you free. Jn 8:32
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staubkorb
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Re: Jetstream from an original Midwest kit
Reply #11 - Mar 29th, 2021 at 12:00pm
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The timer will HAVE to go as far forward as it can get, whichever I use.  Final weight of this puppy is no big issue as the class has a minimum weight of 220 grams.  The completed fuselage as shown is only 30.

I would much prefer one of the new electronic timers with provision for radio DT, but the available one are WAY above my budget both in unit cost and shipping.
  

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Re: Jetstream from an original Midwest kit
Reply #10 - Mar 28th, 2021 at 3:01pm
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Looks great!  I'm wondering if the dt timers couldn't wait till later helping to set CG adjustments.  But as you say wing mount is adjustable.
  

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staubkorb
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Re: Jetstream from an original Midwest kit
Reply #9 - Mar 28th, 2021 at 8:14am
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Fuselage construction is done, save for some finish sanding.  I was contemplating a small mod, with an adjustable incidence tailplane, but it prolly won't be necessary as the wing saddle allows some adjustment by simply moving the wing back or forward.

The ballast compartment hatch caused a bit of head scratching at first due to the formers having to fit INSIDE the effectively closed cavity.  Issue solve by cutting the sheeting to shape and using fuselage cut-offs as spacers. According to plan, the hatch is held in place with a bit of tape.  I then became aware of one of the possible reasons that A1/F-1H models now have such a guppy-like nose (whether this is factual or not...)...

After finally finding my never used Graupner 22.25 gram scroll-type timer (naturally NOT in the box with all my other timers Roll Eyes), I was VERY disappointed that the mounting dimensions were simply too big Sad.  I'll have to use one of the smaller Polish, 3-function units, the red one weighs 15 grams and the gray one 13.  All three have the same clockwork innards.

Tailplane build next on the board.
  

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staubkorb
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Re: Jetstream from an original Midwest kit
Reply #8 - Mar 27th, 2021 at 6:20am
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Tow hook bent up and mounting plate glued to the fuselage bottom.  Most of the top sheeting done last night.

One thing that kinda surprised me is that almost all of the wood is "C" grain and the parts sheets for the ribs (2 sheets) were within 1 gram of each other.  The only "A" grain is the top of the  fuselage and the wing sheeting - all of the wood with the exception of the bottom fuse sheeting is around 7 lb density (bottom fuse sheet is 1/20" @4 or 5 lb - wrong place for light/soft/thin wood Huh).
  

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staubkorb
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Re: Jetstream from an original Midwest kit
Reply #7 - Mar 26th, 2021 at 6:13am
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One has to build an OLD kit to really appreciate the newer models!  I'm not referring to the "modern" CNC/Laser ones, but anything from the 70's onward and pertains mostly to the instructions - leaves much to the imagination - and the symmetry of some parts where the cutting dies can flex (most noticeable on long, straight parts).  Symmetrical ribs should be flipped against each other to make sure that they ARE symmetrical!

I've gotten the fuselage pretty much completed with only the tow hook and top sheeting to do.  I've bent up the hook and modified the mount a bit (plywood) to make it adjustable (the hook mounting is one of the "guess what" areas of the instructions).  Naturally, I spent more time digging out tools and other needed bits out of the Chaos Cave than building Huh.

I'll probably build the stab next.

I jumped on this build after learning about the A-1 Postal on Hippocket and one of the members had a photo of a Swedish model from 1954 that brought back memories from about 35 years ago at a fly-in.  It also fits the requirements for the Postal - so I wrote to the maker and ordered it (it is a really pretty contest glider Smiley).
  

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Re: Jetstream from an original Midwest kit
Reply #6 - Mar 23rd, 2021 at 3:23pm
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Thanks for starting this model and sharing the story.
Good luck with the build.
I think this is the Jetstream that won the 1959, 1960, 1961 US Nationals A1 glider contests.
I like gliders. 
Simpler to build usually. 
As they have less time invested in building them it is easier to risk trimming and flying them with less risk of a crash.
I built 2 x A1.
Golden Wings from Vic Smeed published in Aeromodeller was the best. 
This flew well and straight off the building board. 

Unforgettable feeling watching it going up on the towline and gliding on down to land gracefully.
  
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staubkorb
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Re: Jetstream from an original Midwest kit
Reply #5 - Mar 23rd, 2021 at 11:59am
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Glued up the fuselage sides and bottom.  The bottom 1/16" sheeting needed a fair bit of tweaking - not due to the joint area not fitting (was quite close), but when fitted and centered nose-to-tail, the part looked more like a modified "Clark-Y" airfoil rather than symmetrical Shocked.  The sides, however, lined up perfectly with only the long, bottom straight cut - wasn't quite.  Rather common with a long "straight" die-cut.  All I did was to lightly sand the mating surfaces for better bonding.

One is instructed to glue the 5 formers and the fin to the bottom sheeting BEFORE attaching the sides (3/32") - the sides being glued onto the bottom.  To get the formers halfway centered, I drew a center-line on the sheeting which REALLY showed the asymmetry but once the sides were added,the fuselage was straight and the excess wood of the bottom sheeting will be trimmed away.

I haven't quite decided how I'll get this and my other towliners in the air Undecided.  A lot depends how well my ankle heals - still giving me some problems.  I'd prefer the "normal" launch method and the A-1/F-1H class is not nearly as strenuous as the classic and A-2/F-1A classes.
  

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Re: Jetstream from an original Midwest kit
Reply #4 - Mar 22nd, 2021 at 11:10pm
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Nice looking glider!  I look forward to following your build!  Will you be using a up-start or hi-start to get her in the air or some other form of motivation?  I'm to old to tow one by running with a line myself!!! Undecided Lips Sealed Embarrassed Roll Eyes

I do a little strumming myself.  But it's been awhile for me!
  

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Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Kerak
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Re: Jetstream from an original Midwest kit
Reply #3 - Mar 22nd, 2021 at 9:37pm
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It's truly a small world, Marc and Pete...got my own collection of strings n' stuff...been playin' all my life.  Hey Marc...I've discovered that I have the distinct ability to make whatever I play sound just like I'm playing it.  Grin Grin Grin Grin  Currently got about 15 or so guitars, 2 banjos, 1 mandolin...etc., etc.  For the past few years been takin' time off for balsa n' sticks.  Smiley

Keep on rockin'!

Neal
  

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