cjshaker

I'm happy to finally be building my Boomerang Intro.

Just got Sandor Kruise's gear kit for the Boomerang Intro. Seems like an exceptional bargain! Trailing link struts, with rearward sweeping nose gear (includes plywood frame to mount nose gear), ball bearing wheels, brakes, retracts, air kit, brake and gear valves, carbon sheet to cover main gear openings, etc. I'm astounded at how nice this setup is, and how reasonably priced it was. Got the whole kit for 300 Euros, which worked out to be $400 USD with shipping included. Here is the web page (old price):

http://shop.digitech-turbines.com/pr...2aanl77p8gcb42

I've got the cockpit panel, pilot, and canopy mounted. Also, have the main air inlets mounted and FOD screened. I'm going to mount a couple more air inlets for the turbine in the fuselage hatch. After reading about people getting cooler engine temperatures and better fuel consumption with more intake vents, it seemed a good idea. I'm also going to make and install the engine bypass baffle to force more air into the turbine. Our club runway is at about 3,500' elevation, so I'm assuming air flow will be more of a concern than at sea level. I'll be running a Jetcat P60SE in it, with Futaba S3050 servos.

Am using the Dreamworks 88 oz extended range kevlar fuel tank, and the BVM bubble trap.

Got the Pete Tindal linkage kit on order, too, which also seemed very reasonably priced at 32 Euros delivered to the US.

http://www.petetindal.co.uk/Jet%20Kit%20Upgrades/

Thank you for all of the help and advice you all have posted here before. I've been reading and re reading this list for build hints.

Chris Shaker

Selleri

Had a bit of a fuel spill in mine, so a new fuselage was in order with few mods along the way.

nt flyer

Nice one. Looks fantastic!

Great to see a Boomer in different colours.

Cheers,

Greg

Turbinac

Very nicely done, Selleri!! Good to see a real modellers work and super simple colour scheme looking so good.

Selleri

Cheers, I was thinking about the [link=http://www.rcuniverse.com/forum/fb.asp?m=8697826]Nano minimalistic scheme[/link] but my mate came up with this version while we were working on it.

The view down below.

akaram

Guys, those of you who have a Wren Supersport on their BBs, can you let me know please what are the settings for Acceleration Delay and Idle RPM which work without any problems ? and also let me know at what altitude are you flying and what temperature.

I fly at 1400 meters altitude, temperature in summer is 30 - 32 celsius. I received my supersport with idle rpm of 40000 and acceleration delay of 12, at this setting I had lots of problems mainly when accelerating from idle the turbine would make a cavitation burbling sound and most of the times it would throw blue flames and burn the stab. Then i increased idle to 45000 and acceleration delay to 24, response became much slower but it worked better for me while the temps were below 20 centigrade. Now that the temps have gone up to 30-32C even at an Acc delay of 30 and idle of 50000 the turbine is behaving bad !!! and is super sluggish and slow at this setting !!!

Did anybody face such problems ???

ThomasP

Hi akaram,

The temperture here in the U.K at the moment is a lot different to yours, we are seeing a range of 16c - 26c, however my Boomerang has a wren Supersport, and I have not had any problems, altitude from sea level to 200mts.

Just had a look at my GSU and the figures are as follows:
Max RPM 160k
Idle RPm 45k
Stop RPM 28K
Start / min Temp 100c
Max Temp 820c
Accel delay 015
Deceleration delay 015
Stability 050
Pump Start Auto +1
Pump Ramp 006
Glow Plug 047

Hope this helps.

Regards,

Alistair

akaram

ThomasP,

Thank you for the data, I have all the same except acceleration delay set to 24 and it is still giving trouble (originally from factory it was 12) and the Max Temp is 848C
You are lucky to be flying at sea level with cool weather, i am sure mine would work great under the same conditions you have ! A friend of mine has a behotec and a couple of Jetcats, the behotec exhibits a similar behaviour like my wren while the jetcats just dont care !!! they work great !!! thats the strange thing !

ThomasP

Akaram,

Give those good people at Wren a call, I am sure they will have some advice regarding operating the Supersport at high temp and high altitude combination.

akaram

Thomas,

Sure I did and Sara is very nice and very helpful and they did their best to help ! I downloaded the latest running log + parameters and sent to Sara, she said they suspect there is an ECU problem, I sent the ECU to her. They tested it and found no problems. Have been trying to resolve this for quiet a while with Wren ! What helps is increasing the acc delay to above 25 and rpm to 50k, at this setting the turbine becomes very slow to spool up with high residual thrust making it very dangerous to operate on our short 100 meter runway on top of a hill ! So I guess I will have to wait for winter to come to fly again

cjshaker

Any possibility that increasing the sizes of the air inlets would help?

Does it happen if you run with the top hatch removed?

Chris Shaker

Turbinac

For what it's worth, here are my S/S settings.....trouble free from day one at any temperature here in the UK..
Max.160,000
Min 45,000
Stop speed 28,000
Max Temp. 800
Accel. Delay 015
Decel Delay 008
Stability Delay 050
Pump start Auto +1
Pump Ramp 006
Gloplug 038
It's true that for the S/S you must increase the air intake area to as much as possible.

akaram

Shaker, it does exactly the same thing with the hatch open, so while I do agree that a Wren SS does need larger intakes it is not my main problem.

Turbinac, thanks for the parameters, you are all lucky to have acceleration delay 15, at this srtting it should spool up super fast ! your deceleration delay is also very low, what advantage does it provide ? do you think I can also lower mine the same way ?

Turbinac

It has to be worth a try! What have you got to lose, if it is not working for you at your current settings? Try it for a five minute run, tethered on the ground before you fly it. Also, maybe try it held between two of you and moved to different angles and positions, see if it keeps running.
I suppose you have got the basics right? For example nothing before the pump, in the fuel system, just direct from the UAT into the pump, then the solenoid and filter after the pump? Checked the klunk is clear (especially if its a felt one or the plastic cased filtering type) and hasn't fallen forward in the tank? Checked ALL the fuel lines are clear, including that air is getting into the main fuel tank OK as it empties?

Not trying to put you down.....I've done the wrong thing myself on all those counts in the past. Sometimes it's the most obvious thing you overlook.

cjshaker

Another possibility is that your bearings might be going bad? How do you tell if your bearings are going bad?
Could failing bearings cause the symptoms you are seeing?

A buddy's PST 800 shut itself down due to low RPM as he was taxiing in after landing. When he went to start
it up for his next flight, he heard a 'screech', and his assistant felt more vibration than normal coming from
the engine. Last I knew, he suspected that his bearings were going out. I have not yet heard if that was in fact
the problem...

Chris Shaker

akaram

Hi Chris,
I dont think it is the bearings, the turbine has only had like 4 or 5 hours of runtime and it looks smooth.
I talked to Gaspar Espiell and this is what he said:

" It is normal that the engines become lazy at high/hot conditions. How much... and what is "normal"... difficult to say.
The only way to have clean accelerations is to slow down the process. Looks like you have tried several things, but looking at your numbers, for me, the maximum temperature is on the high side. I would use a maximum temperature of 100ºC less than what the engine show at max rpm. I don't think that your engien run at 748ºc at full thrust, so no need of to have the max temperature of 848. Setting a lower max temperature the ecu will detect earlier a bad combustion and overheating, and will retard the acceleration when necessary, but will not retard when not necessary.
Anyway, you must accept a slower acceleration time in summer than in winter. All turbines are like this. "

cjshaker

Akaram:

I'll be very interested in whatever you learn on this issue, because we live at almost the same altitude, 4,200'.
It has been 97 degrees F (37C) here lately.

We flew my Reaction 54 with its PST 600R at 4395 ft. / 1340 m elevation on Thursday, in about 100 degrees F
temperatures, with no engine problems, except for a failed glow plug.

Hoping to get back to work on my Boomerang Intro...

Chris Shaker

Phat Reliant

Hello All, I just started a build of an earlier Baby Boomerang which I guess had been sitting around for a while, it was in its original wrappings and box, my question is should I re glue what I can get to and secondly the engine, I am stuck on deciding between a Jet Cat P60 or P70, since the almighty dollar is a factor the engine will most likely go in to another model after my training, but which is more adaptable?...

It's my first Jet and from what I have read, the Boomerang is probably the best trainer out there.[8D]


Thanks in advance, Phat.

RC Jets!, I am being told is super addictive..[X(]

akaram

Definitely go for the P70, a friend of mine had a P60 on a Baby and later replaced it with a P70 because the P60 was marginal with very limited vertical. Now with the P70 it is a pleasure to fly and he is very happy !

He then put the P60 on a Tamjets F16, and it is sluggish, slow to accelerate, barely leaves te ground on our 120meter limited runway !!!! now he is looking into replacing the P60 again with something bigger on this F16.

For those who may argue against what I am saying, note that we fly at 1500 meters altitude.

Phat Reliant

Thanks Akaram, P70 is going to be the choice, I did read a lot since posting and there seems to be a lot more I can go to with that turbine.

Phat.

I was given the retracts and replaced the tires (also given), these were incredibly hard and almost broke my thumbs putting them on. For future reference, is there an easier way?

The wheel hubs are one piece types that do not split apart. Picture is in my above earlier post.

Thanks again, Phat.

KC36330

if price is an issue, why not get the P-80 SE??? it's cheaper then both the P-60 and the P-70 and now that it comes with SE throttle response one heck of a great choice.

aquaskiman

My Feedback: (46)

P-80SE Then you can put it in a bigger plane when you get done with the Boomer. I fly my boomer with a Wren 14# turbine at 5200 ft and it works great. I have several turbines but still fly the boomer a lot. It is a fly any time no nerves plane. I will always have an easy flying turbine for those just fly days. George

Phat Reliant

I thought that the P80 power would be a bit much for the plane, the price is very appealing considering, but why is it cheaper?

akaram

It is cheaper probably because it is bigger/heavier thus easier to manufacture. You can fit it on the Baby Boomerang with a few mods to the engine mount. If you had the Boomerang Sprint then you could fit the P80 with no problems at all, it was designed to be able to accomodate this size !

KC36330

if that was the case then the 120 would be even cheaper, Titan even more so and they'd practically give the 180 and 200 away.