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Old Feb 08, 2006, 09:56 PM
Park Jet Guru
jetset44's Avatar
Seattle, WA
Joined Jun 2002
5,589 Posts
Mini-Review
Little Screamers Park Jet Special Motor

Bob at Little Screamers was kind enough to give me one of his new Park Jet Special motors to test last week, so I thought I’d post a quick review here. The Park Jet Special is a special wind (8 turns) of the Little Screamer (LS) outrunner motor, and is specifically intended to provide high speeds on park jet-type models.

To test it, I put the motor in my T-38 park jet, replacing my favorite Himax 2015-4100/4.4 gearing/9x6 prop setup (see pics below). Since the LS motor came with a standard 3/8” stick mount it was a quick drop-in replacement. Flight testing left me VERY impressed with the LS motor --the performance meets or beats the Himax setup in just about every measure. Here’s the synopsis:

* Thrust/Speed – This motor was designed for speed, and it didn’t disappoint. Bob recommended an APC 6x5.5 prop, and in level flight speed runs with that prop I’d estimate my T-38 was doing around 70 mph! MUCH better than the 50 mph top speed of the Himax setup. Thrust/weight with this prop was slightly under 1:1, though, at 15.5 oz AUW. The model could easily climb out of sight after a high speed run (due to inertia), but at slower speeds it couldn’t sustain a vertical line. There was still plenty of thrust available for maneuvering, though. To see if I could trade a little of that top speed for more low speed thrust, I then tested an APC 7x4 prop. The results were much to my liking. Top speed dropped to about 60 mph (still faster than the Himax) and thrust/weight was well over 1:1, with unlimited vertical performance (similar to the Himax). For my kind of flying style (lots of aerobatics) the 7x4 was the better prop, but it’s nice to know the model can be quickly converted into a speed demon with the smaller prop! However, note the test bed here was my 100% T-38 park jet—which is a really large and draggy model for this little motor. Because of the very low weight and high power of the LS motor, I think you could scale the T-38 down to perhaps 75% and get significantly higher speeds while still maintaining very good low speed performance. Bob claims speeds close to 100 mph with this motor on smaller lower-drag airframes, and I believe it.

* Current draw – I put the motor on the Wattmeter with both props and a fresh TP 1320 11.1V Pro-lite pack. The results were (static wide open throttle):

APC 6x5.5: 14.0 amps, 140 Watts
APC 7x4: 15.3 amps, 150 Watts

These amp draws are similar to the geared Himax setup, and are easily within the capability of a TP 1320 pack (which is nice since it keeps the weight of the model down). Bob said not to exceed 18 amps with this motor, and I found that both props stayed well below that limit.

* Weight – In my opinion, this is one of the best things about this motor. The RTF weight with mount, connectors, and prop is only 1.5 oz. That’s HALF the weight of the geared Himax setup, even though the LS motor has BETTER performance! The AUW on my T-38 dropped from 17.0 oz to 15.5 oz, a very nice decrease. But while the weight savings itself is nice, it’s even more important for a park jet since it makes the model much easier to balance. Although my T-38 didn’t require ballast to start with, I had to move the battery aft about 8” to restore balance, from the very front of the fuselage to under the aft canopy. For all of you that are flying with ballast in the nose, simply switching to an LS motor may allow you to save 1.5 oz of motor weight PLUS the weight of the ballast! Another thought that occurred to me is that the LS motor would make an ideal motor for an F-14 Park Jet with twin motors. Two LS motors would provide TWICE the thrust of a single Himax yet weigh the same. Plus, the small 6” or 7” diameter props could easily clear each other.

* Prop diameter – Because the LS motor swings a little 6” or 7” diameter prop, I found that prop torque effects were MUCH less noticeable than with the 9” prop on the Himax. This was especially so at launch, but also noticeable during aerobatics. Plus, the smaller diameter prop is safer to hand launch (more clearance from your hand) and may even be less likely to be damaged at landing (since it doesn’t stick out as much). At first I was worried about the efficiency of a small diameter prop at the back end of a long and blunt fuselage, but I was glad to see this wasn’t a problem on the T-38. Whether it would be a problem on park jets with wider aft ends (like the F-18 or F-15) I’m not sure, but I have a hunch they’ll work fine as well. The larger 7” prop will help this.

BOTTOM LINE – Compared to the previous Himax 2015-4100 setup, the LS Park Jet Special motor provides 10-20 mph higher top speed, similar low speed thrust (with 7x4 prop), similar current draw, significantly lower weight (especially if the model needs ballast with heavier motors), and lower cost ($50 for the LS versus $67 for the Himax). I also found the build quality of the LS motor to be excellent, and it comes with both a stick mount and a firewall mount. Thus, I highly recommend this motor! They aren’t listed for sale yet on the Little Screamers web site, but Bob said you can send him an email to order one.

Steve
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Last edited by jetset44; Feb 08, 2006 at 10:02 PM.
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Old Feb 08, 2006, 11:29 PM
Renegade Fun Forever!!
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Fontana, California, United States
Joined Jul 2004
27,246 Posts
Thanks Steve!! Glad you liked it.

Now imagine that little Baby in the 24" Bandit! Now imagine it again with the 4.75x5.5 with another 6000rpm's Sends the pitch speed to well over 100 mph My Bandit is so fast in dives that many times I'm afraid it won't come out But it always does and it makes the coolest noise over 65mph. I would love to build a simular sized version of the T-38 and I can't wait to get my GGRN A-4 Skyhawk done. That plane should be great and with unlimited vertical like the Bandit, a real show stopper. Those that want to see this motor in action can go to my gallery and watch the King Kitty video's. That's a 30" span plane and it still does better than 70 mph in level flight. After that video, watch the Hummer video in my Gallery!!! That's my pride and Joy motor! Too much for most park Jets, but is built from the same parts just a different wind.
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Old Feb 08, 2006, 11:45 PM
Park Jet Guru
jetset44's Avatar
Seattle, WA
Joined Jun 2002
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Yeah, now I can see how that motor would SCREAM in a 75% Bandit, given how it pushed my big 100% T-38 with authority! I think a 75% T-38 with this motor would be ideal for those that "feel the need for speed" with a scale-like jet.

I had hoped my T-38 would whistle like your Bandit at the higher speeds, but alas, it didn't. But I can see why the motor is named Little Screamer--it really does scream in flight! It's a really high-pitched whine, almost like a jet turbine. Fits the T-38 very well. It's interesting how the motor noise differs in the three motors I like to use in park jets--the eerie-silence of the Axi, the loud gearbox grind of the Himax, and the turbine-like squeal of the Little Screamer.

Steve
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Old Feb 09, 2006, 01:53 AM
Go FASST or go home...
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Bergen, Norway
Joined Nov 2002
3,123 Posts
Where can I buy this Little Screamer??

Really want to build another of these parkjets (the bandit) and totally outspeed the fuel guys at my field

Ben_E
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Old Feb 09, 2006, 05:21 AM
One eyed Corsair
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PARIS
Joined Jul 2005
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Can't wait to test it on my Rafale M !!!!!
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Old Feb 09, 2006, 05:48 AM
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United Kingdom, Wrexham
Joined Jun 2004
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Available In The U.k.

Does anyone know if these are available in the UK??
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Old Feb 09, 2006, 06:41 AM
Registered User
Naples
Joined Nov 2004
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Steve, do you have any means to give the RPM and maybe thrust for that motor?
I am thinking the same road - weight in the rear for a pusher. My (yours) F-15 is almost redy to fly, according to your recommendations the Himax 4100 was already in. I didn't liKe the COG and I do not like to add weight to the nose; now I am installing a Kommodo 273. Weight should be about the same as your new one (42gr); right now I am experimenting with number of turns and different props; I think I stay with 12turns and the GWS Hd 9x5: 8900 RPm and thrust estimated 20oz, 10.5 A. I put it in my heavy (16oz) 3D-Foamy and it hovers easily, of course that is not the best prop for a 3D plane.
Hans
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Old Feb 09, 2006, 11:30 AM
Idle up!
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USA, VT
Joined Nov 2004
5,802 Posts
I was convinced of LS motor quality when I saw the pylon racer vid of the hummer.. what was it.. 147mph in a dive on 3 cells??

LS should link up with 6mm .. be a great kit combo!
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Old Feb 09, 2006, 12:47 PM
Registered User
Edmonds Wa. (Seattle)
Joined Nov 2003
3,926 Posts
HI Guys,

Thanks Jetset44 for the great review, Glad you like the motor.

Now you see why I love having Bob as part of Littlescreamers He's the man for speed! He has been working on these winds for some time now and this is a real winner for sure. I wont even fly one myself as they are to fast for me. I need a little time to get caught up before we can start sending these out. I need about a week. You need to build airframes so it should work fine?

Happy Flying
Scott
Littlescreamers.com
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Old Feb 09, 2006, 01:35 PM
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Buffalo Intl, New York, United States
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Is there a list to be placed on to get one of the new motors?

Jer
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Old Feb 09, 2006, 02:50 PM
Park Jet Guru
jetset44's Avatar
Seattle, WA
Joined Jun 2002
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Quote:
Originally Posted by Loefflerh
Steve, do you have any means to give the RPM and maybe thrust for that motor?
No, unfortunately I don't have a tach or a thrust stand to get RPM and thrust measurements. I usually just rely on MotoCalc to predict performance, though in this case I just took Bob's advice since I don't have the required data to run this motor in Motocalc (Kv, no-load current, and resistance). Bob or Scott--do you guys happen to have the above data so we can analyze this motor in MotoCalc?

Steve
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Old Feb 09, 2006, 05:08 PM
Renegade Fun Forever!!
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Fontana, California, United States
Joined Jul 2004
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Hi Guys,
The Hummer video was on 3 cells. We used a TP 1320 PL and an APC 4.75x5.5 with an AUW of 9.4oz's. The speed was measured in level flight on the 297' pylon course. Watch the video again (in my gallery) and the last pass was from a 400' dive! That pass was 163mph

My 24" Bandit goes 90+ mph with an APC 5x5 Not bad for a foamie! With an APC 6x5.5 it has unlimited vertical and will do 70mph loops I've attached a couple shots of my Bandit.

Steve,
Were you using a 1320 Gen II pack or a Prolite? Your specs seemed a little soft? I get 17,400 rpm's on 17 amos and 175 watts. Confirm your battery for me please.
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Old Feb 09, 2006, 05:17 PM
Renegade Fun Forever!!
rvincent's Avatar
Fontana, California, United States
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As far as specs for the LS Park Jet?? I haven't gotten that far yet I estimate the Kv at 2800-3000 The no load and resistance I will need to get to you all for. The weight is 23 grams including mount and connectors or .8 oz's I use the Cool Running A-12 with all mine as it unloads to about 13 amps in the air. I haven't had any failures with my set up yet and I have hundreds of flights on both my King Kitty and Bandit. I also have this motor on my Jomari Rapid. I have not hit it with the radar yet, but a good guess is 120mph. It's right up there with my Hummer.
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Old Feb 09, 2006, 06:44 PM
It's me Glacier Girl
Joined Aug 2004
868 Posts
Hey Bob,
Is this a rewind on the MOFO? 8 winds of 24 ga.?
Wonder what it would do on the hydro?
Probably rip the tail off huh.
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Old Feb 09, 2006, 06:46 PM
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Edmonds Wa. (Seattle)
Joined Nov 2003
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Quote:
Originally Posted by SHELBY1
Hey Bob,
Is this a rewind on the MOFO? 8 winds of 24 ga.?
Wonder what it would do on the hydro?
Probably rip the tail off huh.

This is a special wind! Shhhh

Scott
littlescreamers.com
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