seravios

i still stick to the prescribed CG. Never touch it ever since.

chris1971

Same here, it flies too well to risk messing it up! We had our giant scale fly-in a couple weekends ago and I got 15 flights on mine over a three day weekend. I had a blast, best airplane I've ever owned. The only problems I had was the canopy blowing off during the flight when the local TV news reporters were filming and A battery pack gave up the ghost thanks to a Triton charger. I burned about ten gallons of Kero and two quarts of Turbine oil! I'm seriously thinking about upgrading to an Elan when this Sprint gets worn out! We have a very large number of spectators every year for our show and people kept asking me "Is that a real jet engine? Sure sounds like it!" I just smiled and said "Just like the ones on the jetliner you fly on!".


Chris

seravios

Cool.........

BaldEagel

I thought jet flyers where the top of the tree in flying terms, it seems that I am the only one on here who wishes to experiment with their airframes to see if they can improve it, or make it fit their own individual flying needs or wants, shame????

Mike

MAJOR SPLAT

HI Baldeagle

I have only had the one flight with my sprint but I am thinking the c of g definatly needs to go back on mine.
The p80 se fitted means I have almost 16oz of lead in her to balance at the stated point.
I found that during the turns the nose dropped very quickly and inverted she requires a large amount of down elevator.

That said I have some other issues I will be addressing first as I have nearly all my down elevator in to stop the plane going into orbit![>:] so the tubine is going to get some adjustment to remove the down elevator trim then when I have all the mechanical trims as good as I can get I will start looking at the ballance point.

Regards

Major.

BaldEagel

Major

Good man, as I said earlier I have mine back about 9.5'' and still think it needs to go back even more, but before I did that I though I would ask if anyone had already done this, seems you and I are the only ones willing to give it a go.

As you say the drop in the turns with the C of G at the recommended position is quite marked as is the amount of down needed for inverted, I have a Merlin 90 in mine and its a lot lighter than the P80, but then I don't use a UAT so the amount of weight up front is minimal, I just want to get rid of some of the lead up front as well.

Alan Cardash says that the thrust line does not make a lot of difference to the Boomers, I would look at your tail incidence, before messing around with the thrust line, unless its obviously out, have you put a 0.25 bit of ply under the whole mounting strap of the P80 to get it level?

Flying this week-end in the UK is off, rain all day today and tomorrow, hopefully I can get out later in the week when it says it may be fine, fingers crossed.

Mike

MAJOR SPLAT

HI Guys

Another question, I am using a DSX9 tx and have not set up crow/reflexed ailerons before I currently only have 90 degrees flap set up, I had a play with the settings but was not sure if the amount of reflex was correct and if it was in fact set correctly.
when the ailerons were reflexed and an alieron input made the ailerons moved a small amount but probably not enough to move the model, can somone post a set up list for the tx to do this correctly

Regards

Major

MAJOR SPLAT

Hi Mike

I had to put a 3/8 packing shim under the turbine to bring it up centered but the turbine is still level, as for the incidence! the stabiliser on mine was a poor fit but is definatly sitting at the intended angle but again I could move it if required.
Thinking about it the turbine angle change may actually make the inverted worse lol!!

I am new to jets but the basic trimming is still the same so I will just do one thing at a time and re-evaluate after each adjustment.
I am supprised that you are at still looking to go back further than you already are with the cg but they say the sprint has a large range.
As long as I can slow mine down and the inverted requires alot less stick then I will be happy and If that means I can remove the lead then so much the better.

I am in essex and its chucking it down so no flying for me either.

Regards

Major

BaldEagel

Major

The basic trimming is the same except for the fast moving air under the tail which gives a negative lift effect which should pull the nose up, so pointing the jet efflux down (effective up thrust) should counteract the trimming you are having to do, but as you say not the inverted, that's why I suggested you looked at your tail incidence.

As to still moving the C of G back, I just like to find the limits of my airframes, the elevator has not become at all twitchy even with the C of G at 240mm, I would still like to get rid of the 200grams of lead I have in the nose, will let you know the outcome, just hope its not another curvature of the earth moment. LOL

Mike

georbeckha

My Feedback: (12)

Hi Guys, I finally maidened my Sprint this past weekend at Michigan Jets. P80se Kero start for power and the standard 125oz Fuel tank gave me perfect balance with the 2500Mah ECU Lipo as well as 2 LiIon 2 cell packs running thru a regulator in the nose. First flight needed about 2 clicks on the aileron and one click down on the elevator and it flew hands off.

Vertical? Out of sight. Speed? WOW. It was even faster in the air than a Falcon 120 powered by an older P80! This become my favorite flyer after the first flight!
Me thinks it is time to sell the ShockJet and move forward. Get someone else in my local club into Jets.

George

seravios

Geo, what is your AUW ? Mine is 11kg with 2.5L fuel.

chris1971

I sent a picture of my Sprint in to AMA for the Focal Point section in Model Aviation and it finally was put in this months (September 2010) magazine! I sent it off over six months ago. I guess they have a lot of lead time.

Chris

georbeckha

My Feedback: (12)

Hi, Yeah. On a not very accurate set of scales the AUW is 10.7kg with 125oz fuel. (That's 3.6L of fuel metric)

George

seravios

http://www.youtube.com/watch?v=sxnONppG38A&feature=player_embedded#!

Sprint vs Rafale (new pilot)

reo

My Feedback: (130)

interesting....who told you that?...

BaldEagel

Every jet pilot I meet. LOL

Mike

skaap2k

I got my Sprint + Engine + Retracts + "Everything" needed to put it together...
I went with a P80SE.. as this is my first jet, I have a few questions

1. How do I position the turbine in the model (regarding forward & backwards position in the fuse)
2. I've read stuff here about having to raise the turbine?
3. The JetCat mount have nuts attached to the bracket, I assume I should drill a hole big enough for these to sit into?
4. I've seen lots of talk about ceramic paint etc etc etc ... Is this necessary for the Sprint?

Many thanks
Rob

BaldEagel

Rob

Welcome to the land of Boomers.

The JetCat is quite heavy and needs to be positioned towards the front of the turbine bay to help with the C of G.

The assermetic JetCat straps need to be packed up off the turbine mounts by approx 6mm it is the packs you put in that need the recess for the nuts under the strap.

The need for ceramic paint and ali covers for the tail is according to where you fly and how your pits ect are arranged, if by circumstace you have started you turbine and put the cover on ect and are then held up before you can fly (others in the circuit etc) then you may have to the tail into wind and the turbine at idle, this will put heat into the fus and could cause overheating, also if you have a hot start the tail could be burnt by the flames produced, I hope that is clear and helps a bit.

Mike

rager24

My Feedback: (9)

I'm looking into getting a Boomerang sprint as my first turbine plane
What do you guys think of the King Tech vs the p80se
I read good things about both of them and the king tech is about $500 less

BaldEagel

Both good turbines, the Kingtech is smaller than the P80SE so to achive the same thrust has to rev faster, hence more noise, the P80SE is amazingly quiet in comparison to anything else, I suggest you look at who in your local area uses what and go from there, its good to have some back up and someone who can come around and help with any problems.

The Kingtech is lighter than the P80 so you would end up with a lighter airframe if you went that way.

I started with a JetCat P80 and never had any problems with it, converted to Kero start and it just started and ran, I sold it to get a JetCat P120SX, I also have a Jets Munt 90 and the noise has to be experienced to be appreciated.

Mike

chris1971

I've heard good things about both too. I have an old non-se p-80 in mine with 18 pounds of thrust and it is plenty. I also had to add quite a bit of weight in the nose to balance it. You might be better off with the lighter Kingtech but the SE has 22 pounds of thrust to overcome the weight disadvantage. My older P-80 has plenty of power for straight verticles and I haven't had any problems with it.


Chris

Xairflyer

My Feedback: (1)

No question really, if you want total reliability and the ability to just fit it and forget it, and will work streight out of the box then buy the P80
There is only one reason not to buy the Jetcat you will probably never learn anything about turbine engines as all you do is give it fuel and it will work everytime.

If you want to save a few $ then buy a second hand one a P80 with 10hrs is the nearly the same as buying new

skaap2k

Hi Mike,

Thanks for your reply I had forgotten to click the notify button so I didnt see your reply until now.

That sounds good - Pictures soon to come! - Hope to have her in flying condition by Sunday!

Rgds,
Rob

BaldEagel

Rob

Xaiflyer is right, it all accords if you are interested in flying or fiddling, if you just want to fly then the P80 is the one to get, amazingly reliable, and with a Kero starter on board very uncomplicated to run, let us all know what way you go in the end.

Mike

seravios

my antique P80 already had 77 hrs on it. Starts everytime,never flameout (touch wood). Going for 3rd service soon.