JETT engineering .46 FIRE - Fuel (max nitro?)
02-27-2015, 01:53 PM
#27
Junior Member
Join Date: Feb 2015
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
Yes...I remember them well. Their team captain was a young girl (cannot remember her name) but she was a strong leader and knew her stuff. She ended up going to work for Boeing. I tried to recruit her to come with us to Lockheed but she was already committed. Our loss...
As to your prop...probably got busted. Hope you weren't expecting it back!!
As to your prop...probably got busted. Hope you weren't expecting it back!!
03-01-2015, 07:33 PM
#30
What is the objective of the contest..?
To see who the most clever "Engine Guy" is...?
To see who is willing to do the most experimenting with props and fuels...?
To see who has the most skillful pilot...?
or........
Is it to see who can build the best payload plane with all the other conditions being equal...?
To see who the most clever "Engine Guy" is...?
To see who is willing to do the most experimenting with props and fuels...?
To see who has the most skillful pilot...?
or........
Is it to see who can build the best payload plane with all the other conditions being equal...?
03-01-2015, 07:43 PM
#31
Senior Member
Thread Starter
Join Date: Jun 2006
Location: granby, QC, CANADA
Posts: 1,407
Likes: 0
Received 0 Likes
on
0 Posts
What is the objective of the contest..?
To see who the most clever "Engine Guy" is...?
To see who is willing to do the most experimenting with props and fuels...?
To see who has the most skillful pilot...?
or........
Is it to see who can build the best payload plane with all the other conditions being equal...?
To see who the most clever "Engine Guy" is...?
To see who is willing to do the most experimenting with props and fuels...?
To see who has the most skillful pilot...?
or........
Is it to see who can build the best payload plane with all the other conditions being equal...?
There are a few different elements.
Design and build an airplane that is light (target empty weight is 8 lbs)
be able to take off close to 30 lbs
Be able to drop a 3 lb sandbag on a target from 100 ft altitude.
The engine is just one element / challenge
03-02-2015, 07:00 AM
#34
While this is true for a competition, an engineering student should always be thinking "out of the box" and working out the absolute strength of materials, giving 110%..... I was a bit involved with the Sunracer competition, and money was no object for many of the schools. They had battery, and solar cell sponsors etc.
03-02-2015, 10:54 AM
#36
03-02-2015, 01:27 PM
#38
My Feedback: (1)
Join Date: May 2003
Location: Orangeville, ON, CANADA
Posts: 8,658
Likes: 0
Received 2 Likes
on
2 Posts
I just watched some video of a competition in 2012 - whooee some of those models are hanging in the air by a thread. And love the take off roll.. waiting for the JATO bottles to fire.
03-11-2015, 07:52 AM
#39
My Feedback: (19)
Join Date: Apr 2002
Location: Cleveland,
OH
Posts: 5,576
Likes: 0
Received 0 Likes
on
0 Posts
I just happened to run across this... i guess the thread is a few weeks old. Hopefully I can assist...
You can run the 30% fuel without any issue .... but I suggest using the heli fuel with slightly more oil in it.
When running with a tuned pipe -- the pipe setup and length "define" the rpm peak and range for the configuration.
The full pipe is prefered for heavy lift -- since you can run it longer and take the boost to increase prop size instead of rpm. For the heavy lift 11x4 or 12x4 would be a good choice.
An example...
I run an APC 12x4 on a standard Sport-Jett .46 and the turbojett muffler combination. Its a great powerplant -- when new (2002?) it peaked out just over 14,000 rpm ------ these days more around 13,700 peak but i rarely set it over 13,000 on the ground. Flown in a P-51 mustang. So not quite heavy lift. But pleanty of performance.
The long pipe gives you a LOT of options -- you can set it long, and turn a 12x4 around 14,000 without question.
Remember that is a peak rpm.. .even with a slower heavy lift airframe, you never want to launch at peak rpm --- as SOON as the engine unloads with forward airspeed, it will need more fuel so you want it set rich about 800 rpm (min).
I know we have set up the SJ-50 and SJ-60L for 11x7 and 12x6 props in the past.
My general suggestion --- for any competitive event, including heavy lift: RELIABILITY is your number one objective. Keep it simple. Pushing for 300 rpm more is sometimes not a good trade. Focus on the fuel system -- make sure that is flawless -- no fuel foam or bubbles ... make sure the engine mount is solid (you can lose a lot of energy and rpm with a poor engine mount), and ensure the pipe is mounted properly.
You can run the 30% fuel without any issue .... but I suggest using the heli fuel with slightly more oil in it.
When running with a tuned pipe -- the pipe setup and length "define" the rpm peak and range for the configuration.
The full pipe is prefered for heavy lift -- since you can run it longer and take the boost to increase prop size instead of rpm. For the heavy lift 11x4 or 12x4 would be a good choice.
An example...
I run an APC 12x4 on a standard Sport-Jett .46 and the turbojett muffler combination. Its a great powerplant -- when new (2002?) it peaked out just over 14,000 rpm ------ these days more around 13,700 peak but i rarely set it over 13,000 on the ground. Flown in a P-51 mustang. So not quite heavy lift. But pleanty of performance.
The long pipe gives you a LOT of options -- you can set it long, and turn a 12x4 around 14,000 without question.
Remember that is a peak rpm.. .even with a slower heavy lift airframe, you never want to launch at peak rpm --- as SOON as the engine unloads with forward airspeed, it will need more fuel so you want it set rich about 800 rpm (min).
I know we have set up the SJ-50 and SJ-60L for 11x7 and 12x6 props in the past.
My general suggestion --- for any competitive event, including heavy lift: RELIABILITY is your number one objective. Keep it simple. Pushing for 300 rpm more is sometimes not a good trade. Focus on the fuel system -- make sure that is flawless -- no fuel foam or bubbles ... make sure the engine mount is solid (you can lose a lot of energy and rpm with a poor engine mount), and ensure the pipe is mounted properly.
03-12-2015, 08:20 AM
#41
My Feedback: (19)
Join Date: Apr 2002
Location: Cleveland,
OH
Posts: 5,576
Likes: 0
Received 0 Likes
on
0 Posts
Good luck to all of the teams competing this year!
03-16-2015, 04:37 PM
#43
Senior Member
Thread Starter
Join Date: Jun 2006
Location: granby, QC, CANADA
Posts: 1,407
Likes: 0
Received 0 Likes
on
0 Posts
Hey guys.
Competition went great. Just going to leave some info here in case someone stumbles across it in the future,
The fuel we ended up running started out as a car fuel blend. 30% nitro and 8% oil. We brought added 2% synthetic oil and 10% castor oil for a final mixture of 20% oil and 26% nitro.
Prop was an 11x5
Glow plug was a merlin hot (same plug dubb ships)
The engine ran VERY well and was super reliable. Always stayed rich .
No head shims were added just to be safe rule wise.
A few other JETT engines were at the competition. IMO it is the only engine worth running many airplanes had difficult taking off/ gaining altitude.
I will second what bob said, fuel system reliability is key. We ran a bladder tank.
Competition went great. Just going to leave some info here in case someone stumbles across it in the future,
The fuel we ended up running started out as a car fuel blend. 30% nitro and 8% oil. We brought added 2% synthetic oil and 10% castor oil for a final mixture of 20% oil and 26% nitro.
Prop was an 11x5
Glow plug was a merlin hot (same plug dubb ships)
The engine ran VERY well and was super reliable. Always stayed rich .
No head shims were added just to be safe rule wise.
A few other JETT engines were at the competition. IMO it is the only engine worth running many airplanes had difficult taking off/ gaining altitude.
I will second what bob said, fuel system reliability is key. We ran a bladder tank.
03-16-2015, 05:09 PM
#44
My Feedback: (1)
Join Date: May 2003
Location: Orangeville, ON, CANADA
Posts: 8,658
Likes: 0
Received 2 Likes
on
2 Posts
Cool! Are you flying at altitude? Or closer to sea level?
If you run out of your custom fuel blend, you could substitute SIG Champion 25% - that's essentially what you brewed. Around here you can only get it in quarts though.
If you run out of your custom fuel blend, you could substitute SIG Champion 25% - that's essentially what you brewed. Around here you can only get it in quarts though.
03-16-2015, 05:14 PM
#45
Senior Member
Thread Starter
Join Date: Jun 2006
Location: granby, QC, CANADA
Posts: 1,407
Likes: 0
Received 0 Likes
on
0 Posts
A agree with your fuel suggestion. Basically rc car fuel was the only fuel we had access to at home before leaving for Florida. I figured it would be best to stick with the same fuel blend for competition as what we used for testing (just one less thing to worry about).
