Hangar 9 Pulse 125 XT

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Pulse 125 pictures


Background Maiden flight Engine Flight statistics
Specifications Modifications Flight experiences Links

Background

After flying my Hobbistar trainer for all of 2011 I was ready for something new. After asking around I decided to go for a low-winged sport plane that could be powered by the DLE 20 gas engine. The Pulse 125 was a natural choice.

I bought the Almost Ready to Fly (ARF) airframe in September of 2011 and began to accumulate the components I would need for the assembly. Later that month, and after a lot of time online spent chatting with Pulse 125 owners, I got started.

The assembly turned into a build*. As things progressed it became evident to me that some areas of the stock configuration could be improved, such as:

Before I knew it, the ten hours' assembly time quoted in the manual had turned into more than a hundred. Of course, a lot of custom work was involved in making changes to the design and fixing mistakes made as I went along.

*Typically, putting together an ARF is an "assembly" while putting together a kit is a "build". I spent so much time on the Pulse and changed it so much from its stock configuration that I'm comfortable using the latter term.

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Maiden flight

I maidened the Pulse in 2012 on a windy day in April. Right away I noticed that the stock gear, which is swept back considerably, gave the plane a tendency to nose over while taxiing. So much so that holding up elevator when taxiing downwind would cause the tail to rise. My first attempt to solve this problem was a riser block for the landing gear. That didn't help much, so I ordered some aftermarket gear. Problem solved for the 2012 season... but I prefer the appearance of the stock gear so for the 2013 flying season I've taken a suggestion I found online and moved the stock gear forward on the fuselage.

The maiden flight went pretty well considering the face that I was terrified. Luckily the CFI was beside me reminding me to breathe, and another good buddy was there to help with getting the plane trimmed. In retrospect it was probably too windy for a maiden that day, but everything worked out in the end.

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Engine

The DLE 20 gas engine I put in this plane did not originally run as reliably or pull as hard as I had hoped. I've made a number of modifications to the engine that have improved the performance: Smoother idle, better transition and more power. The engine has never been to draw fuel by hand flipping for the first start of the day, though I've since heard that some DLEs won't draw fuel into a dry line unless the throttle is wide open. The DLE 20 is out of the Pulse now, but when it goes to its new home - the Hobbistar - I'll give that a try.

In the meantime there's a new powerplant in the Pulse 125 - an RCGF 32. It's a rocket!

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Flight statistics

Total flight time: 9h 56.5m
Takeoffs: 93
Landings: 90

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Specifications

Wingspan: 1930 mm (76")
Length: 1590 mm (62.5")
Weight: 5.2 kg (11.5 lbs)
Powerplant: RCGF 32
DLE 20 - removed for installation in the Hobbistar
Receiver: Futaba R617FS
Receiver battery: 5-cell 6.0V 2700 mAH NiMH
Ignition battery: 4-cell sub-C 4.8V 4200 mAH NiMH
Ignition kill: Smart-Fly fibre optic
Aileron servos: Hitec HS-645MG x 2
Elevator servos: Hitec HS-345BB x 2
Throttle servo: Hitec HS-645MG
Rudder servo: Hitec HS-645MG

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Modifications

Coroplast skis

Flight experiences

2014-06-08 First flights with the RCGF 32 installed. Engine running well, trim good with slight up elevator required. Lots of power and speed, very loud. Second flight, landing gear tore out of mount on landing; prop broken. An extensive repair was required, during which I moved the gear even further forward. For the first time the wheel centres are forward of the leading edge of the wing; I'm hoping this will cure the tipping tendency once and for all.

While the plane was on the bench I fabricated and installed a silencer in the muffler. We'll see how effective that is when I next fly the plane.
2015-09-20 Five flights today. Silencer has some effect. Engine running rich; leaned the low end a little with each flight. Apparent crack in muffler flange; oil leaking out rear bolt hole. Took fellow member's advice - fit a tight washer under the bolt head. Will fill the void with Permatex Ultra Copper. First flight with Biela 17x10 3-blade carbon fibre propeller... very nice.

Landing better than ever. Remember to release elevator when main gear touches down. RCGF 32 power continues to impress but does not detract from flyability in the least.
2015-09-24 Four short flights, mostly chasing low end tune and low idle. Rudder low rates reduced from 86% of full throw to 70%; much less twitchy. Leaning the low end speeds up the idle, enough that to run out of sub-trim and throttle trim. Moved the throttle servo arm 1 notch clockwise and reset the trim - just a little up trim was needed for a slow but reliable idle. Had to increase upper throttle end point from 99 to 125 to regain wide open throttle. Low end much better - less 4-stroking and less mess on the airplane. Lower idle a big help on landing.
2016-04-24 Four flights. Engine is running very well with slight four stroking in the lower RPMs. Trim is just right. A blast to fly!

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Build photos

All photos

Vendor page

Airframe manual

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