Hi All,
I just wish to give you all my impressions of the Jet-Central Rabbit VT-90 turbine, I have had the envious opportunity to be the first person in Australia to run these little beauties, I don’t work for Jet-Central nor do I have any connection with the company other than through Ausjets.com. Please be patient with my long winded story and I apologize in advance for it's length or for boring the hell out of you!!

I must acknowledge Rob Orrock, the owner of Ausjets.com here in Australia, he has been nothing short of superhuman when it comes to helping me out to establish my little turbine workshop and test facility here in Sydney, for this I thank him very much. Rob looks after the day to day running of Ausjets.com, I just do my best to look after, set-up and service the engines he sells and take customer technical inquiries etc.

Please be aware that I do not fly model aircraft, so I cant comment on the installation and flight response etc... I have just under 30 years experience in the aviation industry and am a turbine engine technician by trade, primarily involved with the Rolls-Royce (Allison) 250 type helicopter engines and their fuel delivery controls, systems and governing equipment, I've also had some experience with the Pratt & Whitney PT6 range of turboprop and turboshaft engines.

Firstly I wish to thank Eric Clapp from Jet-Central, the man is a pleasure to do any sort of business with, be it just a quick call on the phone or service advice from the other side of the world. I cannot speak highly enough of him, he goes out of his way to make sure everything is put right..... special thanks also go to Juan Ruiz, Felipe Nieto and all the people at the Jet-Central facility in Mexico for their help, advice and expertise.

Now, on to the Rabbit..... My first impression of the Rabbit when I lifted it out of it's specially constructed case was, "geeze, she's light", the engine itself weighs in at just 1kg (2.2lbs), as usual.. and I guess most of us do it...I look up the backside and into the front of the engine, yes… we all know what's in there, a turbine wheel and a compressor wheel, I did a double take on the compressor though, it's not the normal cast turbocharger type jobbie, it's a beautifully machined billet item, worthy of praise, I'm not sure of the material but it looks very nice indeed with just subtle differences from the normal blade angle and design.

The size of the Rabbit engine is no secret, for example, it closely resembles the Wren MW54 and the JJ-1400 in external dimensions, essentially it is in the 14lb thrust class size. The finish and build quality of these engines is exceptional, everything is "just so", no unsightly gaps, no misaligned this or that, it's just right!

I unpack everything, spend an hour or so reading the very concise manual, then set about getting her setup on my test bed enclosure. I also have a digital thrust gauge, external atmospheric and independent exhaust gas temp monitoring equipment so I can give independent and impartial observations of my findings without "guesswork". The ease of setting one of these up is very painless indeed, all fittings, wiring, filters and tubing is already done, no soldering, cutting, trimming etc is needed, it's just plug and play...as it should be.

Once it's all together and ready, I do a final check of the connections, batteries, start gas and plumbing, all is good. I flick the switch and the data terminal comes to life. I do a quick run through of the available settings and test the starter, solenoid valves and do a pump prime to get the fuel up to the engine, I adjust the gas % to suit the sea level conditions here and....we're ready for a start. Ok, trim up, throttle up and back...I look at the data terminal and I see the normal "glow plug test" indication, but nothing....no starter engagement, no engine spinning, nothing!! I scratch my head, then as I’m looking for an errant wire or connection, 8-10 seconds later the starter is on it's way, caught me a little by surprise I must say.

Normally with a glow plug, the FADEC tests the system to make sure the plug circuit is good, then it will initiate the start sequence, just a second or two. Not so with the Rabbit, I understand it has an internal ceramic element, similar to the kero start machines I suspect, it takes time to heat one of these up, hence the 8-10 seconds delay, it seems like and eternity to what we’re used to with a normal glow plug.

The start, light-off and ramp up to idle is, as is usual with a Jet-Central engine, seamless. 40,000 rpm later we’re sitting pretty, smooth as a baby’s..!! I let it run for a minute or so and let all the temps stabilize, the data terminal reads just on 510c, my EGT gauge reads ~460c, it’s situated 45mm to the rear of the tailpipe in the exhaust efflux, calculations suggest I should be reading something in the order of 40-50c less than that indicated in the tailpipe itself. All is good. I do the “slow up and slow down” thing with the throttle to enable the ICU/FADEC to learn my TX and the pump voltage requirements etc.. which is normal for just about any turbine engine these days.

Ok, lets see what this puppy can do!! At a nominal 40k idle, the engine has to make it to a 152k rpm maximum. I slam the throttle to the stop and….Damn!, what a rocket, 2.78 seconds later we’re sitting at 152k !!! The noise is fantastic to those like me who like turbines. That’s a 112,000 rpm increase in less than 3 seconds, amazing indeed. I see an EGT spike of ~640-650c and it settles down at ~590c, very nice indeed. Personally I find it a little abrupt in it’s acceleration, but for some I guess it is what they’re after with their model aircraft. Deceleration is the same, very quick indeed and with no hint or suspicion of a flameout, settling down to a smooth stable idle again, very impressive.

I let her sit at idle again for a short time, now it’s time to see what sort of power we have here. I slowly take the throttle up, watching the thrust gauge with interest, slowly but surely the numbers increase, (now bare in mind we’re talking about a 14lb class size engine here). At 100k I see just on 6.5 lbs, Pfffttt nothing special I think to myself, but I press on, at ~120k the thing just about goes ballistic and the numbers roll through with great speed, 10, 12, 14, 16……geezus, at 152k I see 19.81lbs on my gauge monitor….this cant be right!! I do the same thing three times… and three times I see in excess of 19.6lbs average, there is no mistake.

It must be said that I have very good, dense air here with relative altitudes in the very low 100’s a lot of the time, only on very hot days do I see relatively “poor air”. So I guess not everybody will be able to achieve numbers like this.

In conclusion, the Jet-Central “Rabbit” has got my nomination for “Turbine of the year”, without doubt a real work of art in my humble opinion. The Jet-Central people have indeed done their homework with this engine. Worth every penny?? Indeed it is.

Cheers and all the best,
Smithy.

That spool time is EVERYTHING , When you need it...

Ah, see, there you go, I don't fly model aircraft, you've got a big advantage over me then.

Cheers,
Smithy.

Thanks for the review Brett. That was very informative. This engine does sound amazing and I would love to get my hands on one of them.

Andrew

Great review. I have been looking for a couple of smaller engines to power my scratch built B-1B project and I am now convinced that a pair of Rabbits will fill the bill. Good thrust to weight ratio, fast throttle response and the most significant item, 95mm case size or less to fit the 12th scale size of my project. Will probably place my order around Christmas for an early 2009 delivery so I can get them installed for a Springtime maiden flight. That's the plan, anyway.

Roy

Awsome project MM.Love the B-1B.

B-1 Fantastic... Jettastic?? This needs it own thread.... Now.

I have a beta web site that has all the construction photos. It has been in the works for about 8 years but due to my health and my wife's health, it has been a slow build. Now I am within about 6 months of completion and if the economy doesn't go in the tank, I will be able to buy the engines and get the project completed. Up until the past several months, there has not been a small enough engine that would fit the criteria that I needed to power this beast. It is built 1/12 scale so the wingspan is 139 in and the length is 144 in. It will weigh around 44lbs dry and with 240 ozs of fuel (110 ozs per engine) around 55 lbs wet (trying to keep it within the AMA limits). So 38lbs of thrust will give me about .7 to 1 thrust to weight which is what I have calculated for a successful build. I have the maiden flight planned for April/May time frame. When that happens, positive or negative, then I will release the site and use it for a build thread.
Thanks for the interest. The B-1B has been one of my favorite jets for a long time.

Roy

We all dream about models like this, perhaps 1% of us can make them reality. A beautiful (& ambitious!) project, good luck seeing it through to completion Roy. Hope you & your wife have good luck on the health situation too. - John

Roy, what's goin' on...

Listen, I'm retired Air Force and I love my B-1B. I've been wanting a flying model of that Puppy forever. For a reasonable price, I will pay you to build another one for me-No BS. Think about it...

Thanks in advance...

...

nice.

Thanks for the comments. I didn't want to hijack the thread with my project. Only interested in the comments on the Rabbit. So keep the info coming on the Rabbit's performance, things you like and don't like, and fuel consumption, etc. Thanks

Roy