RMJ Raptor E700 gasser

[trillian]

There have been a few detailed build threads already on this gasser conversion so I won't duplicate what has already been done but just want to do a little overview of my build.

My kit arrived in April the day before I went away for 5 weeks to the USA so that was the first delay in getting started. The 2nd thing that delayed my progress was that I bought an engine from an engine builder and it took a little longer than expected but I was told it was ready the week before I was leaving for the US so I told him to wait till I got back to post it. Anyway, a couple weeks into my trip and he had a family issue come up and went home to Portugal and is actually still there! So the engine I paid for back in April is still, presumably, sitting at his house in the UK. In the meantime I bought a 2nd hand Hanson 300 from a forum member so the build resumed...

Once I got going it has gone together very easily. The only bit that is not a simple bolt-on affair is that a small section has to be dremelled out of the upper frame to allow clearance of the clutch bell but this is a few minute job with a cutting wheel.

The bare E700 donor airframe starts like this:


Once the mod for the clutch bell has been done the rest just bolts together and you get this:




The engine mount has to be placed on the engine and the custom clutch holder goes on. After that the engine bolts right in. I was pleased to find that everything lined up very nicely, the start shaft spins freely and the clutch bell does not drag etc. There is a little room to move the clutch bell bearing block a little bit so for now I have it where I think it's probably aligned but there's probably a way to run the engine just to the point of engagement with the bell bearing block bolts loose and then tighten them when the clutch is engaged. Maybe that's OTT, we shall see.

In any case the rest of the build is all standard stuff, mounting servos and electrics etc.



I got some yellow Trex skids to match my custom Buckers canopy.



It's getting close now. Just throttle linkage and wiring to do, put some grommets in the canopy etc. and setup the FBL unit. I am totally loving the paint work Phil did, it looks simply awesome!









One point, make sure to fit the carbon fan shroud extender before you mount the engine as it's a bit fiddly once the engine is in the frames! I discovered this the hard way.

[GIXERMAN]

a nice review sheryl, hope you enjoy.

[trillian]

a nice review sheryl, hope you enjoy.

Thanks, I'm sure I will. I have been flying a Helix (Trex 700) with a stock Zenoah 260 for a couple months now and have been very pleased with it and the Raptor should be just that bit more refined, a little lighter and with a more powerful engine, so in theory at least it should really rock.

---Just to add, the weight with all electrics including a 3000mah LiFe RX pack but without blades is 4.94kg. So with blades (approx 190 grams each for mains and about 15 grams for a pair of tail blades), it should be about 5.33kg dry.

I am using: Ace RC DS1015 servos on the swash, Align BL850H on the tail, Spektrum H6040 on throttle, CY Total-G FBL, powered directly by a 6.6 volt LiFe pack. I'll also fit an Opti Ultraguard so that will add 30 grams or so.

The pipe is an RJX which is a bit heavier than some of the other choices. I'm hoping it is as quiet as the Hatori on the Helix as it's very civilised, basically not much louder, if any, than a large nitro.

[helijohn]

That's a beauty and I think you've done a great job.

[Rob Barnes]

Superb Job , it looks really good and I love he canopy its the best ive seen yet !

[trillian]

Superb Job , it looks really good and I love he canopy its the best ive seen yet !

Thanks Rob and helijohn! The design was inspired by the Diabolo and I cleared it with Gerd beforehand. Phil had recently done an Alees Rush 750 canopy with the CF effect in a red outline so it was a combination of those ideas. I gave him a Diabolo pic as an example on the stripes and he just ran with it from there.

[helijohn]

I have a similar set up fuel wise on my Kalt but I now wonder how to drain off any surplus fuel if the tank is not empty at the end of the day.

[trillian]

Just a little update to add a couple things. It's now ready to maiden, I have run the engine briefly just to make sure it's not going to give me any trouble (it started on the first pull, one slow pull with the choke on and then the first real pull it fired up imediately). And I wanted to make sure nothing leaks etc. One thing I did notice when just idling the engine is that the tail pushrod started to vibrate quite a lot from the vibes, but the fuel in the tank was not anywhere near foaming so I think it's just a normal amount of vibes, no more than you'd get with a .90 nitro. The point though is that I moved one of the rod guides up a bit so hopefully next time out it will be better.

I have a stator gator but as I had never used one I thought it wasn't working because I could not get a sensor light in my Total-G setup. I have been told since then that they don't generate a pulse when just turning the engine slowly, soooooo, maybe it does work. But there's also the possibility that it's not compatible with the Total-G. In light of this I decided to try a regular governor sensor and I found a spot on the engine where the sensor is close enough to the magnet in the flywheel, it's just in a corner of the fan cover on the exhaust side. This is also fortunate because it is right below one of the engine mounts so as it turned out the carbon sensor mount that comes with the Total-G fits perfectly and puts the sensor right where it needs to be. You can't see exactly where it ends up in this pic, I can get a better pic if anyone wants to use a normal gov sensor.

This is an alternate canopy I got from a forum member, I think it looks really nice as well. Which brings me to one other small item, I noticed the canopy was able to rub just a little on the throttle linkage. It really wouldn't be a problem as it barely makes contact (and some builds may not have this issue if the linkage ends up closer inboard). The fix for it was very easy though, just a little fuel tubing on the bolt holding the link arm and this keeps the canopy a few mm clear of the linkage.

[Guest]

Looking good can't wait to hear about the maiden. You've found a new throttle arm position which is probably the reason why it rubs it wasn't intended to go there. It goes on the hole above but if it works no biggie.

MJ

[Planehazza]

That looks epic. Really interested to see the power it delivers. Is it comparable to an OS91 etc yet?

[trillian]

Yes, you are correct! I could not get the linkage working properly around the canopy mount with the links and rods I had lying around and things kept ending up at strange angles. I played around with it quite a bit and eventually settled on this solution. I'm sure there's a tried and true setup you guys have done that can be copied and it will just work but I happened to have some link rods of certain lengths and it seemed the path of least resistance.

Looking good can't wait to hear about the maiden. You've found a new throttle arm position which is probably the reason why it rubs it wasn't intended to go there. It goes on the hole above but if it works no biggie.

MJ

[trillian]

That looks epic. Really interested to see the power it delivers. Is it comparable to an OS91 etc yet?

Rob and maj could answer that better than I can because they have flown this same engine and airframe as well as the nitro conversion.

So far my gasser flying has been with a stock Zenoah 260RC (26cc) and to me it feels very similar in power to an OS91 on 15% nitro, but that's a subjective thing. The RMJ Raptor has a Hanson 300 which is 29.5cc and has been balanced and slightly longer stroke crank etc. so it should be quite punchy.

I do kinda like the way gassers have the look of what appears (relative to a nitro) to be an oversized engine and pipe, 'seems more OTT.

[trillian]

I want to do a quick update now as I have finally been able to really fly the Raptor. I did a few brief maiden / tuning flights in the last few weeks. The previous outing I had setup throttle curves and enabled the governor but then accidentally caught the tail blades on the ground and chewed about 1.5 cm off them and as I didn't have a spare set with me the flying session was cut short. But this Sunday I took the Raptor out to really try to dial it in. I had also received a TRM pipe during the week so fitted that as well.

So these were my first flights with the governor enabled, pitch and throttle curves all set to approx ranges, tail gain already set etc. I first flew it with SAB 690s and +/- 14.5 and it's very nimble and just does not bog at all doing the 'big air' type stuff I do. This is the Hanson 300 3Dmax engine and TRM powerpipe. The only thing I have to compare with is my Helix with a stock G260 / Hatori pipe and as you would imagine it is way more powerful.

I am very pleased with the power and it really doesn't feel like 6kg in the air. I'm sure you'd feel that extra mass doing some types of aggressive 3D moves but for smooth flying styles it all just works very well in my humble opinion.

I ended up flying all the fuel I brought with me, which wasn't very much really but it's more petrol than I've ever burned in a day before, in fact on my final flight I wasn't paying attention and ran the tank dry at which point the engine cut imediately. Fortunately I was already bringing it back in to land anyway so it was an easy low level auto.

At the moment I have a CY Total-G on it but I'm going to swap that out for a VX1 as I'm seeing a few little niggles that I don't want to spend time chasing and I think the VX1 gov might be a bit more flexible.

One thing I didn't mention before is that I chose to use the original canopy mount positions. The RMJ conversion does allow the front mounts to sit lower so that the canopy rides closer to the skids in the front. The reason I didn't do this as yet is because it does require a little bit of cutting around the pipe so I wanted to see how it would look before doing this with my Buckers canopy (the one in this pic is a Fusuno that had already been trimmed around the pipe). The other reason is that I am using long-ish 3000mah LiFe packs for the rx and the canopy cannot sit lower with the pack on top of the tray in front. I actually don't mind the way it looks but just wanted to mention that it can be setup to have the canopy sitting lower in front.

You can also remove the recoil starter and top-start it like a nitro which saves a bit of weight and will make it look sleeker but I like the convenience of not having to carry a starter with me. There are ways to make the recoil starter removable and I might look into that at some point.

[trillian]

Now we're talkin!

Today I finally got to really fly the Raptor gasser properly since installing a Spartan Vortex and I am very pleased . My first maiden with the VX-1, a couple weeks ago, was perplexing because it was trying to roll to the right and to make a long story short, it was simply due to me somehow accidentally bumping the trim on one of the aileron servos so that the swash was not at all level. I don't know exactly how I did it but in any case I discovered the error and this time it flew pretty much perfect right from the start. I was seeing a little wobble in a hover last time so I bumped the swash gain down to about 46 (no wobble this time), the tail gain is at 34 and holds fine.

For me, this is the most nimble and capable gasser I have flown. I think the dry weight is something like 5.5kg (due to leaving the pullstart on and kinda heavy servos) but it feels very light in the air. I have +/- 13.5 pitch and the Hanson pulls steadily with ease, no sign of bogging in the least.

I'm not even running it flat-out either, my idle-1 headspeed in the gov is 1770 which I think equates to 12,390 rpm. Idle-2 is 1890 and it's very quick at that headspeed.

[George J]

Best gasser you can get, looks great Sheryl........nice canopy.