X-Treme Jets 1/7.5 Rafale or How I`ll spend my Summer vacation (and all my money) - Page 4 - RC Groups
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Jun 20, 2009, 02:43 PM
Lee Liddle
Knife Liddle's Avatar

Fan/Motor Testing

I got some motor/fan testing done last night. I have a Neu 1521-1.5y that I bought last Fall for my Falcon 120 that was powered by a single TJ-100 fan. But I didn`t realize that the dia on the 1521`s is slightly larger than the 1515`s so I haven`t been able to test it in the TJ.

Note: My TJ-100`s are very early production models and won`t accept anything larger than the 1515 series motors, but the new versions will, although the motor case has to be turned down a little to fix and Tam can do that at his store.

Anyway, I took a chance and bought an Easy Tiger 100mm fan (the $30 reinforced nylon version) because it said that it would accept the larger motor, and I thought that I might put the TJ rotor in the ET housing at least for some tests.

I decided to first mount the ET rotor. It needed some balancing and needed the blade length to be equalized, but after that it was running smoothly.

I made a quick thrust measuring stand with some cheap drawer guides and a digital fish scale from WalMart. This is nothing fancy and has a little drag, but it gives me a good idea. I used a homemade intake ring that I made for the TJ on the Falcon and it doesn`t fit exactly. There is quite a bump where the fan lip meets the intake ring. So it could be better.

I was very happy with the results.

11 lbs of thrust
45k rpm measured with an optical tach

The fans that I`m running on the twin Falcon only give about 9.5lbs for the same 3.5kw on the smaller 1515-2y motors, and I`m only running them at 3kw and about 9lbs..

This (the total 22 lbs of thrust) will be good enough to fly the Rafale for sure, and there is a little more to be had by adding 3.7 more volts for those who know my history. That should push the power up near the 4kw range for each side (8kw total! If that`s not quite enough, I can up-grade my TJ-100 fans to accept the 1524 motor that Tam is working on and get up near 10kw.
Last edited by Knife Liddle; Jun 20, 2009 at 02:59 PM. Reason: added title
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Jun 20, 2009, 02:58 PM
Lee Liddle
Knife Liddle's Avatar

Airframe progress

I`ve decided to make the control surfaces removable so that they can be removed and painted off the plane when I`m ready to paint it. The pin hinges are put together with a small aluminum rivet. I removed one to check the diameter of the rivet and found that it seems to be exactly 1/16th inch dia, so I`ll use a long piece of 1/16" music wire as the pin. So that`s what I`m working on.
Jun 20, 2009, 08:34 PM
Lee Liddle
Knife Liddle's Avatar

Better Motor Test

The test I did last night was just a quick test. I didn`t have an efflux tube attached and I was using the 3500mah zippy packs which took an extra cell to hold voltage near 12s levels at 80 amps.

Today I charged up my new XPS 12s 5000mah pack (this is 3 x 4s) and installed a proper efflux tube. I used a 74mm exit dia. I`ve ordered a new V3 air-speed sensor from Eagle Tree. I`ve very interested in the efflux speeds. The force against my hand held in the efflux behind the fan is tremendous.

The results after about 30sec of run-time were...

4040w (just over 4kw)
44.4v (packs held 3.7 per cell at 91 amps!!)
10.5 lb thrust (lower thrust expected with efflux tube)

To say the least the XPS packs performed awesome!! I only did the short test because I want to break them in carefully.

I`m plenty happy with this motor. It weighs 5.5 oz more than the 1515 motors so it can handle longer stretches at these power levels than the 1515`s can.
This is exactly the power level that I was looking for. I`m guessing that on 13s the power would increase to approx 4.7kw (47v @ 100a). May have to try that someday with a CF rotor.
Apr 22, 2012, 01:51 PM
Registered User
Hi Knife,

whats happend to your Projekt? I am also thinking of Building a SM twin Rafale...
Apr 22, 2012, 02:08 PM
Lee Liddle
Knife Liddle's Avatar
Well I hacked it up to fit a pair of 127mm fans in it. Now that power levels are way up on the 90-100mm fans, I wish that I would have left it stock. Still haven`t finished it. I think the stock airframe with a pair of 4kw 90mm fans would be an awesome jet.
Apr 23, 2012, 12:18 AM
Registered User
techspy's Avatar
Nice build! I attempted a Flyeagle Rafale with a Stumax fan. I gave it up because I wasn't able to fabricate intake ducting and couldn't find anyone to make me a set. Did you find a set that would fit 90mm fans?

Apr 23, 2012, 06:47 AM
Lee Liddle
Knife Liddle's Avatar
Check with Tamjets. I think that Barry worked on a set for Tam.
Apr 26, 2012, 10:14 AM
Watt me worry?
Madmax1965's Avatar
I know this plane will be ballistic...........Remember I followed your twin build on the Falcon 120 and installed two 90mm Wemos/ARC motors in my falcon..........too danged fast for me so I removed them and went back to a single fan..........

Godd luck and I am following this thread.....we want video of course.
Sep 16, 2012, 03:18 PM
Registered User
Hi all,

Plane arrived at my door :-)
Here are some pictures from the factory...

My plan is to build here with twin Stumax 100-45 and HET 700-83-975. This setup is good for 6,5 kg thrust each.
Retracts will be converted to electric with Lado series 666 and also gear doors i will do with Lado.

@Knife Liddle: If it is okay, i will continue my build here in your tread...

Sep 16, 2012, 04:36 PM
Lee Liddle
Knife Liddle's Avatar
I like the color scheme. Like I said, I wish I would have left mine stock now that I have some strong 90-100mm fans that would be perfect for it. I`ll enjoy your build. It should be a nice project.
Sep 21, 2012, 07:36 AM
Registered User

LADO retract conversion

Hi all,

here are some pics from the retract conversion with the LADO e-cylinders.

just disassemble the retract, drill a new 6-32" thread in the "cross bolt" (dont find a better word ;-) ) and assemble the retracts. All togehter in just 30 minutes :-)
Sep 21, 2012, 11:31 AM
Registered User
Hey Stephan,

wow, looks nice, looking forward to see it in person.

Sep 22, 2012, 01:30 PM
Registered User


going on with Canard installation...
Sep 25, 2012, 02:13 PM
Registered User

Front Gear installation

When fhinished with main Gear i also will post a video of gear operation...
Sep 26, 2012, 09:04 AM
Registered User

Main Gear

Hi all,

just mounted the main gear and removed the turbine shelves :-)
I moved the main gear a bit forward to better rotate at start. Thanks Gregg :-))

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