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Apr 06, 2016, 07:49 AM
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SF-24 MotorSpatz motorglider


A quick squiz around these parts would indicate that we don't have any info on the VQ MotorSpatz (MotorSparrow) scale powered glider so I thought I would just do a few brief notes on assembly for any that pass this way in the future.

I came upon this model as I have been enjoying flying my 3.5m Ka-8B, but it's a bit big for park flying, so I set out on the hunt for something similar, but smaller.

Requirements were that the model should be a scale representation of an actual powered glider; sized around 2.5m W/S so it would be suitable for park flying and ridge soaring as well as club flying; ARF balsa as I ain't got much building time; maybe able to ROG and 3S powered so it will be a passable thermaler.

Found several contenders, but the one that took my fancy was the MotorSpatz from VQ Models in Vietnam.



The SF-24 MotorSpatz was designed in Germany as a powered version of the existing Spatz glider and was first flown in 1960. Around 50 were made and a few are still air worthy in Europe with a couple flying in the USA.





The VQ model ticked all the boxes and had a cool colour scheme as well. Had a hunt around and found the best deal at my old mate Gustav Staufenbiel in Germany. I have been buying from this outlet for many years and they periodically have some good seasonal sales, so I always keep my eye on them. They have several outlets in Germany and got bought out by Horizon Hobbies last year. I figured that would be the end of their special sales, but they let rip with some good spring sales this year and the Sparrow made a return trip half way round the world back to south asia.

The model came with a power package comprising motor, ESC and prop. Overall, I was pretty impressed with the kit. A few little QC niggles, but otherwise good value for money. Nice covering job with the covering being printed and of the sticky backed vinyl type. This stuff gives a stronger finish than shrink covering, but is slightly heavier and, of course, you can't shrink it if it gets wrinkles. A nice touch is that they give you a couple of spare bits for any repairs.

So, on to the assembly.

The included manual is satisfactory and I started with the tail feathers just a standard build. I replaced the stock Z bend push rods with some threaded rods and replaced the elevator horn with a stronger one.



Had a few QC issues with this area, but a bit of modelling got them fixed.

The model is supplied with some softwood dowels for the locating pegs on the wings. Didn't much like the look of them so replaced them with same sized cf tube and ran the front one right through the fuse and glued it inside to form a compression strut. The wing joiner is an aluminium tube which is probably OK, but I epoxied a c/f tube inside it to beef it up a bit.



There is space around the prop area for air to get in, but no provision for air to escape, so I opened a couple of holes in the fuse out of the way under the wing and attached some covers the spare covering came in handy.



Up to the business end I just made a 13mm block to mount the motor on giving it a few degrees of down and right thrust.



Motor is positioned well and the cowl is a good colour match to the fuse. The model is 1/5.6 scale you have to provide your own pilot.




Some Corona CS-238MG servos should do the trick and fitted well (also used on the ailerons).



Beefed up the hardware again on the aileron controls.



Set up is:

ESC: 40 amp
Motor: Pichler Boost 25 980kv
Prop: 10x5E
Battery: 3300mAh 3S

The manual recommends that the CG be set at 68-72mm from the l/e. This looks about right, but I have read a couple of reports of the model being hard to control at this setting and in one vid the model tip stalled a nose dived into the dirt. I checked the decalage with a meter and it looks OK, so I think a rearward CG must be the problem. Will set it at 60mm for the maiden.

Well, it was a pretty quick build and she's ready for the maiden just got to wait for a nice calm sunny morning.


Last edited by KiwiKid; Dec 26, 2017 at 08:12 AM.
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Apr 07, 2016, 12:29 AM
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She flies!! Went out this morning and had a couple of great maiden flights. I can see why a few people have had problems with this model - the recommended CG is way off. I had moved it forward to 60mm from the l/e which worked OK, but she rolled off the top of a couple of loops on the first flight which is a dead give away so I added some more lead taking the CG to 57mm and she flew sweet at this point. It's strange as this position looks too far forward, but it certainly is needed and may have something to do with the general layout of the airframe and shortish nose section.


Anyways, really a fun model to fly and looks great. Has a good glide rate and should be a good ridge soarer with a folding prop fitted.

Vid to come



Last edited by KiwiKid; Dec 26, 2017 at 08:14 AM.
Apr 07, 2016, 03:55 AM
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One thing I found doing the first field set up was that the method of wing attachment using Allen screws was a pain as they are fairly stiff and you have to work at a 90 degree angle inside the fuse.

I have the wings on several of my planes held on with zip ties with tape for back up so have installed this method on the Sparrow using hooks epoxied into the wings with slots opened up at the Allen screw points for the hooks to pass through.
Last edited by KiwiKid; Apr 07, 2016 at 05:05 AM.
Apr 07, 2016, 03:03 PM
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Vids up, watch it in HD

On the second flight I tacked a Mobius camera on the l/e of the wing, so a bit of AP is spliced into the vid.

(2 min 43 sec)
Jul 13, 2016, 03:58 PM
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Having had two enquiries regarding the instructions - here is a link to them: http://www.vqmodel.com/NewVQModel_Gl...nstruction.pdf
Nov 19, 2016, 03:19 PM
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Well, a few months on and I have been really enjoying flying the Sparrow. I have been using an 11x8 folding prop in anticipation of doing a bit of slopin' when conditions are right.

Some AP pics from a flying buddy.
Last edited by KiwiKid; Mar 05, 2018 at 02:36 AM.
Nov 20, 2016, 01:15 AM
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Looks very nice and fine vid.
Oct 27, 2017, 02:54 PM
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Hi kiwikid love the plane.. so glad you shared that story and the great build. Please put some more updates about the plane and what you have done with it.

I'm working on this project below and might adapt it over to electric.

What advice on power do you think I could try... Power and motor size..

I cam across this thread on this Prototype 2-33 that Dave Sanders had made for possibly TMRC sailplanes I believe. I was wanting to build something very similiar in the design but try to give it a little more scale and realistic look to it as well.

Link of the 2-33 prototype that Sky King had built. https://www.rcgroups.com/forums/show...-SkyKing/page2

So, this is what I have come up with and have been working on now for the last 2 months (off and on as life allows me) my own version of a foam and balsa/ hard wood fuselage design. I wanted to create something for Hi=Start launching since I live in Atlanta and no slope flying around here for me. Trying to build it very light but keeping the durability to it's best. Using PINK foam and will be covering with the Titebond Newsprint method.

I am old school and built a lot of gas A/C over the years but never a sailplane, and never attempted a scratchbuilt from plans. So a first in some respects.

Photos of where I am at in the build.. More to come as I move onto finishing the fuselage and start on the wing..


https://www.rcgroups.com/forums/show...d-Scratchbuild
Last edited by flyguy017; Oct 27, 2017 at 03:26 PM.
Oct 27, 2017, 10:01 PM
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Hi flyguy, the Motorspatz is still going strong and I fly it regularly. I struck a bit of a problem with it in that our mid-summer sun had an adverse effect on the wing covering causing it to wrinkle to the point where it was effecting the model's flight characteristics. This was the result of VQ using a sticky backed vinyl covering on their models that does not shrink with heat. Fixed the problem with a partial recover of the wing and she was good to go again.

Interesting project you are working on. Thanks for the link to the 2-33. For a model like the one you are building a 3cell set up generating around 300W with a 40amp ESC would be ideal. Not sure what the wingspan is, but you could work out an appropriate sized battery based on how much weight you need to balance on the cg.

Regarding fitting a motor, you might like to have a look at this thread where the chap has fitted a motor to a foam Parkzone Ka-8: https://www.rcgroups.com/forums/show...h-Folding-Prop
Oct 28, 2017, 09:12 AM
Registered User
Hi kiwikid - thanks for the great reply.. this is my first attempt at getting into building a glider. I have been flying gas r/c for many years since I was a younger lad. But completely new to the world of the electric stuff, so still need to do some more learning and reading on everything.

I live in Atlanta so no slope flying here for a glider, my initial idea was to build a semi-scale 2--33 and use a hi-start system for launching. But, i'm building it with a foam wing wing and concerned about the launch. So that is why my interest in making it a electric motor assist and going that route.

I'm making it a 79" inch wingspan. The fuselage is a hybrid of square stock and balsa with foam filled in for stiffening and shaping of the final surface. To my surprise it is actually coming out very sturdy, and pretty light. No idea of all up weight yet.

So based on a 79 " wing, would you still suggest a 3 cell set up generating around 300W with a 40amp ESC would be ideal for this? What size prop ??

Looking at your photos of the servo/ battery location I'm concerned that i may not have enough nose room area for a battery location. I will have to doing some more design work.

What is the other electric plane in your photo that is not the MotorSpatz?

Yes, thanks for the thread foam Parkzone Ka-8: I did find that and have it open in the browser as well as your thread.
Oct 28, 2017, 10:02 AM
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Greetings flyguy, yip the 3 cell setup should be fine for your model. The MotorSpatz uses a 3 cell 3300Mah battery and has a 98in w/s. It is a bit on the porky side as it is quite strongly built. If you have had a look at the vid above, you can see that it can loop from horizontal flight with three quarter throttle and hand launches well so has all the power it needs.
I use an 11x8 folder prop on it, but prior to that had used a 10x10 fixed prop. The folder was fitted for slope soaring and I just tend to leave it on permanently now.
Yes, getting the layout right is important. I note PJ said he had to place the battery (1500Mah 3S) around the leading edge of the wing of the 88in w/s Parkzone Ka-8.
The model behind the MotorSpatz in the pic is my 3.5m Phoenix Ka-8B. This is really just a larger version of the MotorSpatz and I got the MS as the Ka-8B was a bit big for park flying in a couple of parks I frequent. A friend and I fly our Ka-8b's together often and they are great thermalers and slopers.
Last edited by KiwiKid; Oct 28, 2017 at 10:14 AM.
Oct 28, 2017, 11:42 AM
rigibahn
PJ PJ PJ's Avatar
Nice planes just the way i like them.
The Swiss flag on wings and rudder do they have a special meaning. With the registration # HB-682 on the fuselage you must be a Swiss. The Swiss flag is one of the best national flags since it comes right from the start with a big plus in it.
PJ




Quote:
Originally Posted by KiwiKid
Greetings flyguy, yip the 3 cell setup should be fine for your model. The MotorSpatz uses a 3 cell 3300Mah battery and has a 98in w/s. It is a bit on the porky side as it is quite strongly built. If you have had a look at the vid above, you can see that it can loop from horizontal flight with three quarter throttle and hand launches well so has all the power it needs.
I use an 11x8 folder prop on it, but prior to that had used a 10x10 fixed prop. The folder was fitted for slope soaring and I just tend to leave it on permanently now.
Yes, getting the layout right is important. I note PJ said he had to place the battery (1500Mah 3S) around the leading edge of the wing of the 88in w/s Parkzone Ka-8.
The model behind the MotorSpatz in the pic is my 3.5m Phoenix Ka-8B. This is really just a larger version of the MotorSpatz and I got the MS as the Ka-8B was a bit big for park flying in a couple of parks I frequent. A friend and I fly our Ka-8b's together often and they are great thermalers and slopers.
Oct 28, 2017, 12:22 PM
Registered User
Greetings to you kiwikid.. thanks again for all the input. Yes, I have seen your video and that was very nicely done on the MS. Looks like a very nice stable flyer, just what i want to achieve but smaller scale.

What Mah battery size should I target? I have a new Turnigy D 35 36 / 8 1000KV motor from a friend. Is this way to much motor for a draggy glider?
Oct 28, 2017, 08:58 PM
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Thanks PJ, the Swiss scheme was chosen by the manufacturer. I checked and the rego has not been allocated to a particular plane so is just made up. I like the Swiss scheme and added it to the glider in my avatar - enlarged pic below.

flyguy, as I mentioned earlier it is often a good idea when building a new electric model to get it to the point where you can check the cg and select the battery size based on the weight needed to balance on the cg. That way you do not end up buying batteries that are too heavy. The motor you have is a fairly grunty brute and may be too big for the model. It will provide plenty of power, but I am concerned that at 102g it will be too heavy. Again, maybe wait till you are in a position to check the cg and see how things work out. Stubby nosed gliders often need a bit of weight up front so it is really a case of "suck it and see".

Here's the HK blurb: https://hobbyking.com/en_us/turnigy-...ner-motor.html
Looks like a prop 10x10 or 10x8 would be appropriate.
Nov 02, 2017, 08:46 PM
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Thanks for the great input and advice on everything. I'm brand new to the world of electric, I've been flying since the 80's but it has always been gas.

I just picked up a used Maxford Storch that came with a Futaba FP-T7UAF radio. It was a great deal and also came with 3 batteries that are 2200mah, 3S and 25C.

The plane has a Turnigy 3532 with a 11x5.5 prop on it. I also picked up a used triton EQ charger that now I have to figure out how to use. I have a extra computer power supply that I pulled from a old PC and going to see how the guys on here and at my local field are setting charging systems up now these days.

I'm going to use your size requirements here and pick up some different size motors, props, and ESC to have around and play with. I picked out a couple below as possible choices from Hobby King..
Turnigy Park450 Brushless Outrunner 1200kv.. it weighs 66 g
Turnigy Park450 Brushless Outrunner 890kv

I really want to keep the power to a bare minimum so that I can generate a nice climb under power but not a lot more than that. Just like you said so that I can keep the weight low. What are good motor choices when moving to a size even smaller than a 450 size.


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