ASW 28 ARF
4,2 m GFK
This article is taken from a forum and translated from
Dainish by the author, there have been made some editing and some notes have
been left out, use of this article in parts or pictures is only allowed with
the author’s accept.
Last update :02082004
Translated from: RC-Unionens
forum
Subject URL: http://www.rc-unionen.dk/nytforum/topic.asp?TOPIC_ID=4364
08/07/2004
Author: Claus Rimestad
Subject: ASW 28 ARF 4,2 m GFK
Postet : 11/06/2004 01:07:55
Searching after a big glider I found the ASW 28 ARF 4,2 m GFK from http://www*modellbau-klimm.de/ (substitute * with .) to 339€ it sounds cheep, the question is how if the quality is OK.
With post and packets the price would be 339€ + 38€ = 377€
After talking with Modelbau Klim I found that you could get a full GFK ASW28 for 599€ but I found the 377€ OK so I ordered a kit with a winch hook and a retractable landing gear. So now I just have to wait on the post to arrive.
Author: Claus Rimestad
29/06/2004 12:17:07
Then the post arrived, a huge packets he
could just have it in his van. The model whose ordered in Germany but whose
delivered from Pragh, I have expected that, looking at the price.
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All the parts looks fine, right now I can’t find any points to criticise,
except how to install the link to the already build in breaks, there must be a
way but right now I do not know how. Maybe I can dig something out from the
foam?
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According the building instruction the winglets shall be glued to the wings,
this is from my point of view a bad idea this will make transport difficult. In
the tip of the wing is no wood just form.
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Not bad to the price, there is all needed fittings, until now I don’t miss any
thing. Now time will show, or there might pop something up when the instruction
is studied. The ordered retraceable landing gear and the winch hook is in
backorder, this might give me some trouble because the gear shall be build in
as one of the first steps sampling the fuselage.
29/06/2004 23:46:46
I have decided to make the winglets removable, this will be the best solution.
Now the questions are coming, how much force is needed in the servo for the
break, is 1.8Kg enough, how much will the wind influence on the needed force?
Is Multiplex wing mount a good solution for holding the wings in place and
maybe also the winglets?
I found the production company in Praha : www.s2g.cz they
have more models you can have a look.
01/07/2004 11:33:55
Now I start building.
The wing and the winglets are glued together with a rip of plywood in the
plywood are to bras tubes glued with polyurethane half way in the winglets and
half in the wing. This glue will expand and will fill out the space around the
bras tube inside the winglets.
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The winglets are cut of. Now I found the first thing to complain the winglets
and the tip of the wing do not fit well together, there are a difference in the
profile, if they are going to be to visible I will make some filling later,
right now I don’t wants to destroy the cowering on the wing, this must wait.
.
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Now the winglets and the wing can be disassembled, now I just have to cut 4
carbon tubes to make the joint. Later I might mount Multiplex wing fix, I don’t
have them right now.
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The Elevator servo bay inside the ruder, there is place fore at least 6 more
but I have no need for them there. If the elevator servo needs service I planed
to cut a service entrains between the hinges for the ruder, to do this I
substitute the tree metal splits in the hinges with one long 0.8mm piano for
easy removal of the ruder, The service hole is not made right now, it can wait
until the day I need it.
The two metal nuts for fixing the elevator are glued inside with epoxy.
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In the nose is mounted a home made release system for the tow, the block is made out of delrin.
04/07/2004 23:34:34
I have not received the landing gear yet , I have two possibility’s I can wait or I can ignore the landing gear right now, I wants to make the kit ready for flying so I just ignore the gear right now.
05/07/2004 11:56:48
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Tow hook in the nose, the wire is operated by the servo.
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Instead of the two horn for the wire that are included in the kit I decided to
use a carbon tube, there is drilled a 3mm hole and the tube is glued in with
epoxy. Why carbon? Yes I have an dear that to many metals part that are not
connected to anything might generate static electricity or when touching other
metal parts will generate noise the carbon tube will connect the two wires and
keep them on the same static level with one wire I can connect the wire system
to the “– “ on the battery.
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The servo for the ailerons are two Dymon 250MG, and I can’t get a mounting
system for that, so I make my own from a thin plywood with balsa sandwich
supports for the servo screws.
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This looks OK and now it is easy to take out the servo for service.
Now I also found the way of installing the pushrods for the breaks, the breaks can be disassembled using a screwdriver to release the tree plastic arms. With the breaks removed the pushrods can be mount on the breaks and then installed breaks and pushrods in the wing.
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The elevator servo in place, there is made 2.5mm thread for a nuts for extra
security. Now adjustment off the length of the pushrod is possible from
outside.
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I would like to use the model with winch start. I glue the plywood for the
servo and the hardwood for the winch hook with polouritan this is possible to
remove later, the hook might also make a conflict with the landing gear.
The connection for the wing servo are made with Multiplex high power
connectors, inside the fuselage the connector is surrounded with balsa, the
balsa are glued to the fuselage with epoxy and micro balloons. The connectors
are fixed in the wing and in the support hole with silicone.
The canopy is glued to the interior with epoxy and micro balloons, the
instruments are from the ASW28 homepage
Now I just need 10 minutes with dry weather then I will sample the plane
outside to make the last adjustments and then it is going to see the ear.
05/07/2004 16:32:07
The different problems is always showing up when the things are put together
the first time. The 18mm steel tube is too long, it looks like the hole are not
deep enough in one wing. One 4mm thread for the elevator is not working
correct. One wing connector is not placed right there is a 1-2mm space between
the wing and the fuselage. Missing decals.
CG adjustment. I make a list with the different things needed before
“ready to fly”.
05/07/2004 18:54:34
Now I have made all the missing things and adjusted the CG to 75mm from LE. I
have mounted a peace of plywood on top of the hook release servo for the 5 cell
2400ma NIMH battery, and the needed led is glued in the front, I forgot to put
the led on the Weight I would like to know the weight of the model but it is
too late. The weight ready for the first flight is amazing low just 3900g
05/07/2004 20:59:32
With just 3.9kg I don’t think that I will have problems in the winch start.
Later I think that I will make new winglets like the 18m ASW28
07/07/2004 23:21:04
The weather forecast is terrible but I found a short period with dry weather but not the wanted low wind. I whose without my starter and my photograph but I couldn’t wait. First I made some range check on the radio and then two hand launce it whose just flying like a dream even the wind didn’t seems to bother it, then I set up the electrical winch. I spotted out a area with low grass and no big stones, I have to tell that my flying field is a big moor land with primarily low vegetation like grass and heath only for gliders.
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The wind level made me a little worried, but on the
other hand if the winch have problems pulling the 3.9kg the wind might help.
Ready with the ASW28 in the winch hook I found it difficult to have one hand
free for the radio so I had to use both hands to hold the ASW28 I tide the wire
until I couldn’t hold the ASW28 and launched it right forward, it took a wired
jump forward lowered the tail and start climbing up without any tendency of
instability, I looked at the shape of the wings and released the foot from the
winch because the wings made a flat U, I didn’t want to brake a wing in the
first start, the wind took it to the top and a little down on the elevator and
the wire released and the parachute opened. I had expected to adjust something
but there whose no need for anything, after trying out curves to left and right
I prepared for landing, round for the final and nose down breaks out, the
estimated speed and height whose not for breaks, the wind also had its
influence, breaks in, but it whose already too late the speed and height
couldn’t reach for the way home I just had to led her down in the grass 150m
out, these breaks are weary efficient.
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These pictures are taken from the winch battery, I started a video sequence
with 15 frames/sec.
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After 5-6 winch starts I found some air going up and whose surprised how easy
it is to curve with here in the stream, the stream whose moving fast with the
wind but I got good height but I whose also far out so it took almost all the height to get back but total flying
time of 11minutes whose not so bad for the first time. 
Positive:
Low weight. (Depending on the equipment used) I have not made any thing in the fuselage stronger and I have been flying several times and still I can’t see the need for anything.
The wing seems to be strong, I have bended the 19mm steel tube in a winch start.
Price compared to contents.
All needed fittings included and in a OK quality
Negative:
Winglets joint and shape of profile on winglet compared to wing.
Canopy and interior, it looks OK but it is difficult to glue et together with a nice fit afterwards.
Elevator ruder joint, first the right place for the elevator is not shown and the shape on the ruder fits not to the elevator, material must be moved in the front on the ruder
The ruder shape in the hinge line could have been made more elegant.
After many winch starts I have selected the low weight and will not mount the landing gear, it will reduce the strength of the body which I need for winch start and the winch hook and the gear need to be mounted in the same area and my number one flying field is not suitable for landing gear.
I have mounted Multiplex wing fix in the joint to the fuselage. I have been thinking about doing the same on the winglets.
Winch start in low or no wind is mush more difficult and the ASW28 might drop to one side and jump off the hook in low altitude I have tried it 3 times and each time there whose altitude enough to make the final and land the right way. I have tried loops and roll and the ASW28 can just do it, stall looks more dangerous the ASW28 might drop several meters before it turns around and gaining enough speed to get back to normal flying don’t do the stall in low altitude it might be fatal.
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Technical:
Servo:
Alierons : Dymon D250MG
Elevator Dymon D250MG
Ruder : Dymon D250MG
Breaks : Dymon D60
Release hook : Robbe standard
Receiver : Multiplex 9ch DS IPD
Battery : 5 * 2400mA Sanyo.
Weight : 3.9kg
02082004:
After bending the 18mm steel tube in the wing several times, I decided to make a Carbon tube out of carbon rowing, 125 rowing and epoxy pulled into a thin steel tube with a inner diameter of 18mm, after drying for 24 hours the metal is removed just like opening a can. This is strong and is not bending, if some day the ASW28 is having a hard landing or impact crash the carbon might break and hopefully reducing the damage on the fuselage to a minimum, if the steel is bending the wing or the fuselage might be damaged because the steel will not break just bend. I think the original steel tube is too soft.
Picture from inside the cockpit. In front the release servo for the pull hook in the nose on top of it the battery, next to the receiver is the ruder servo. I do not use circuit breaker just a plug that can be connected. that’s more reliable.
