KJ66 Conversies

[Gerald Rutten]

Somehow fuel seems to be burning too late, maybe due to bad mixture. Please look at items mentioned here, try again and then we look furter.

Rgds,
Gerald

This is what I mean, after a few runs the front CC plate should look like this on the inside:

Yours seems cleaned by wet, unvapourised fuel. So the airtubes need to be hotter and not being cooled by the cc air holes. Again, also the needles MUST touch the air tubes walls or otherwise the fuel droplet will travel unheated and unvapourised through the airtube and into the cc where it will burn too late giving very high egt's. The droplets need to travel along the metal of the tube wall for best vapourising.


....and some years lots of flying it lookes like this! 8)

 

[freestiler_it]

Very very good, we modified the needles and we made them touch the tubes waĺls. We made holes 0,5mm (from 5 to 5,5) and the result is this:

596degrees at idle (44300)
570degrees at 66000rpm
615 at 75000rpm
700 at 90000rpm
740 at 100800 rpm.
We are Very happy of this result. ...now we will put the exhaust cone to see modifications

 

[freestiler_it]

To be precise we enlarged 0,5mm only half of the 5 mm holes doing Just one yes and one no (5 mm, 5,5 mm, 5 mm, 5,5 mm , 5 mm, 5,5 mm etc)...it is usefull to make all holes 5,5 mm to reduce higher the temp? Thank you everybody for helping Expecially super master Gerald! Thank you

 

[Gerald Rutten]

Very good indeed! You see, one step at a time works the best. You can try larger but I would address something else first.... I have the impression you have a massive unbalance which can be heard from the high pitch wining noise of the engine. (I could be mistaken by the upset tone from camera?) Maybe you found it yourself as well, I think I saw you feeling/touching the frame to feel vibrations, right? If so, this need to be solved first before trying anything else. An imbalance can have a huge impact on egt as it absorbs big deal energy. (Let alone "eating" your bearings...) This very well can increase temps by more than 100C at upper rev's. Try to solve this first. After this is ok you may proceed structural items.

Another small tip..... don't stand aside the engine too long, at 90 degrees angle from the engine is the most unsafe place to be when something goes wrong.....trust me!

Rgds,
Gerald

 

[Gerald Rutten]

Will need to sort out a wet start issue and get the keroplug finished first.

Looking at the film I think that maybe too much kero is poored in at start preheat phase which drops in the cc unburned. When start phase switches over to normal kero fuel ring this get's burned first. once it's gone the engine starts beautiful! Try to decrease initial kero feed to burner or maybe try to shorten the preheat time by lowering the end preheat temperature by 20-40 degrees. Nice temperatures though!

Rgds,
Gerald

 

[Slowswede]

Thanks Gerald! I will try a few things tomorrow evening and post what I find out here. There is allso a bit of a build thread of mine on gtba, but that forum is sadly allmost dead. Still, lots of good info to be found there.

 

[freestiler_it]

We putted exhaust cone :
This is the result
http://youtu.be/1b80wQoR4XQ
What is the exhaust cone diameter you use in your GR130?

It is a litle bit dark but after all we can see pretty good the new test:
Idle temp 605-590 (the more is started and the more temp goes down... )
60000rpm temp 680
82000 rpm temp 700-720

We have balanced the comp-diffuser all togheter with the cc assembled, no vibrations, it was table that is not good, and during that test we saw a kero excape from a tube that we provided to substitute.
What you suggest? We have to open the exhaust cone diameter or the cc holes to make temp go down? Thancks for Read and help[emoji4]

 

[Gerald Rutten]

Interesting video's at night! They look really dramatic and are nice to see if you have burner inconsistency, ie hotspots. This looks like the rear end will melt off in a second but that's always the case when seeing an engine in the dark. The temperatures are important and doesn't look that dramatic. Maybe exhaust is too small. I use about 50mm but that is with no cone sticking out, you might need to recalculate the exhaust surface as I explained before. Idle and mid range temps are looking good, you are for sure on the right track, very well done, you will get there!!!

rgds,
Gerald

 

[freestiler_it]

Thanck you Gerald but I can't find in the past posts: what you mean when you Say "Recalculate the exhaust surface"....is there any formula i can use?
I thing in this Way your support is essential because we never made It before.
Thank You master [emoji2]

 

[Gerald Rutten]

No problem, here it is:

Nice shop, mine isn't any better, it works perfect!

There are different exhaust types which all can be used, no big difference. As long as the gas path is aerodynamic with not too steep angles. Search this thread for different types of exhaust I made, take one convenient which is easy for you to make. For the 130 engine your total outlet surface area must be in the region of Ø51mm. If there's no bullet sticking out this is in fact the diameter you are looking for but maybe it needs fine tuning by closing/opening further, depending EGT's. Before doing any of this your engine must be in good order or else it is useless. If your exhaust center bullet/cone is sticking out you need to calculate the exhaust surface area. First calculate the outer ring (1/2 diameter square root, times Pi 3,14) and then subtract the inner diameter surface at the exit.

Rgds,
Gerald

 

[Gerald Rutten]

This drawing of an example clarifies my explanation:

 

[freestiler_it]

Very Clean explanation Gerald....is it possible that our flame diameter is bigger? We tried with a 51mm diameter without bullet but we saw a very high increase of temp and a reduction of rpms (turbine doesn't finisch the starting procedure ) ...is it possible that hour diameter flame is in the 53-54mm mesure?

 

[freestiler_it]

We modified the cone serching for a better result. ..this is what we obtained :

 

[freestiler_it]

[media=youtube]L-bcjDgHRoc[/media]

Idle temp (44300) 598-609 degrees
83000 rpm temp 700-720

We will modify a litle bit more the exhaust cone and Probably we will substitute the bearing... if this is the result we are happy and we will try our engine making maiden fly with our F-4
phantom

I Hope the trust will be enought [emoji16]

 

[G J Broekhuizen]

wait

Very nice model.
To fly with it, the engine must run perfectly at 120000rpm.
the temperature should not be higher than 700 degrees.
do not fly to be carefully.
too little pressure. it costs your model

the sticks are red

 

[freestiler_it]

How can we increase pressure?

 

[G J Broekhuizen]

thrust

How can we increase pressure?

I mean thrust.
What is the weight of your plane.

 

[freestiler_it]

It is very light....it flyed many years ago with 6kg pulsoreactor 's thrust. ....now it is setted for turbine fly.....without fuel and turbine inside it is only 4 kg

 

[Gerald Rutten]

Gr220

Van de week pakketje binnen gekregen uit zwitserland, turbinewiel en NGV van jetmax, Dieter Albisser. Het is de 74mm variant die ik voor mijn 'GR220' ga gebruiken. In feite is de motor precies hetzelfde van opbouw als de GR180, echter met nog iets grotere compressor en turbinewiel. Dezelfde turbinewiel levert Dieter ook aan Frank turbines die zij voor de FT250 gebruiken, 25kg zou dus mogelijk moeten zijn!!! Echter om die hogere flow in de motor toe te laten zal ik de diffuser aan moeten passen, deze is nu in de GR180 limiterend. De uittrede zal soepeler moeten gaan en ik heb al enkele ideen hoe ik dat wil gaan doen.

Het zal echter allemaal niet zo'n vaart lopen, stukje voor stukje maar uiteindelijk moet deze tor in de F16 en mogelijk nog een andere, grotere kist......

Hier de reeds bestelde onderdelen, compressor is ook ongeveer hetzelfde als de GR180, ook hier grotere diameter van 78mm bij een inlaat van 60mm.

Grt,

 

[Berto]

en mogelijk nog een andere, grotere kist......

Een F-16 min 1?

Geweldig als dat allemaal wil lukken zo Gerald