BaldEagel

Rob

How many flame/hot starts have you seen when the operator has put liquid gas into the turbine, it just seems to me that the occurance of hot starts/flames comming out of the back is less frequent with a Kero start, I am also a firm beliver that getting rid of the Propane element of turbines is a step forward in the safety of our operations, next we have to get rid of the LiPo, at Bickley jets a few weeks ago an Elan went in and it was the LiPo's in the front that ignited, both fuel tanks had be ejected and where yards away from the source of the fire and did not burn, this I was straight from the unfortunate owner not hearsay, not only that but A123's are so much easier to handle.

Anyway back to the Reaper, I now have all the bottom sheeting on and will start to build the canopy and hatch next, I must say this is going together well, anyone who has not built a kit before should have no fear of putting this one together, one hint if you are don't use CA to put the triangular piece's on the bottom or to attach the bottom sheeting, CA does not sand very well its too brittle, use a simple white glue and then if you must go around the inside with Epoxy to reinforce the sheeting too the formers.

Mike

EDIT: to add pic

Robrow

Mike

Its funny how experiences can differ, I've not seen liquid propane put into an engine, if it is it's probably down to a lack of the correct training and/or operators not having a proper understanding of correct procedures. I have however seen several failed kero starts where fuel has pooled in the bottom of the engine casing only to cause flaming problems on the subsequent start. I also never advocate carrying onboard gas.

I'm with you with LiPo's although I've only seen problems post crash with them. I use either Nicad, NiMh or A123s, I like the rapid top up. The latest Jet Central engines have Duralite Lithium Manganese as a safer alternative.

Reaper's looking good, you will enjoy flying it.

Regards

Rob.

siddus74

Hi boys,

Recently got the jet bug and have aquired a couple of turbine trainers almost ready to fly, both have the wren 54 installed . . . the Reaper has functional canards, wheel brakes and retracts. I have only flown it once, god what a rush - 3 circuits and a long long landing. I felt like a dog with two **cks!

The boomer has only been in the hanger for 2 days - both were 1K each and have gas start. I traded most of my hanger so I have 2 turbines and a black horse speed ar .40! (not quite that bad but not far off!)

dw_crash

My Feedback: (6)

Siddus74.

I have been flying a Reaper for almost 3 seasons now. The trick to land is to get the plan into HIGH ALPHA. Flying slow, nose high with the throttle controlling altitude. If you do this, the landings are short and quite easy. Remember, if set up correctly, The Reaper will not stall. Rather, the canard stalls, the nose drops a bit, it pick up speed and keeps flying. Real gentle.

The thing I most noted. This plane bleds off speed quickly. Try pulling high g turns without adding throttle and the plane slows and tucks it nose down. You come out of the turn pointing downward. Rudder helps to prevent this, to a point. So I learned to keep the speed up and do sweeping turns.......

Mine has retracts in the wings.....Be gentle on them. The foam core wing is not the stongest around the gear.

Dave

siddus74

Dave,

Thanks for the advice, I have only a single on mine and the landing was long. From what I gather the jet flyers seem to like the flying / landing capabilities of this model but the looks of the plane are an aquired taste.

I like mine . . . What servos do you have in yours? Mine has some really high spec JR digital's but they can only run on 4.8v and I wanted to replace the 35mhz SPCM rx with a 2.4ghz Spectrum RX but want to run 6v ideally to protect against brownouts . . .

I do think we over spec the radio in our models . . .

BaldEagel

You can't overspec the battery in a Spektrum set up.

Mike

alasdair

Just as an aside, the only burned tailplane incident that I have seen was due to a kerostart JetCat not firing the first time, but it fired on the second attempt and the unburnt kero from the first try fried the tailplane of a Boomerang XL.

I have seen many Reapers. They fly very well and most have had modest engines (Wren 54) and do not need airbrakes. You just need to get the speed low and the nose up to use the delta wing's high induced drag.
At the Blackpool Fly-in I saw this yellow Reaper in the attached photo fitted with a Merlin 160
Over the top, or what!!
As you can see it has an airbrake on the fuselage top.

How about this other idea though? I used the canards of my CARF New Rookie as airbrakes (in addition to the belly airbrake) and very effective it was too. You need about 30 or 40 degrees of up movement so that they are fully stalled. Then you get plenty of drag, a bit of lift, and as a bonus you get extra pitch stability.

dw_crash

My Feedback: (6)

Siddus74,

My Reaper has a long and checkered history......See thread Easytiger Models under Vendor talk. So, to get into the air at a minimal cost, I used Hitec servos for the canard and elevator. The one step above basic digital servo. There were $50 from the local hobby shop. With one per surface, that is plently. So aerilons, I left the older Futaba analog servos Curtis installed. They were, in their day, a good servo and they do the job here.

I use a Polk's Hobby Tracker 8 radio system. It has a fully synthesized transmitter and receiver on 72 mHz. This and the servos work OK with a 5 cell 2400 mAhr NiCad battery pack. Last a whole day with needing charging. Nothing special. Just something I know works well and I trust.

Dave

BaldEagel

Alisdair

I use about 80deg of up on the canards also on a Rookie and that rearly slows it down, I have it programmed so I get extra Elevon movement when the canards go up to ensure I don't run out of pitch control.

Mike

siddus74

So interesting thoughts, I would be concerned about getting massive amount of uncontrollerable lift causing an uncontrollerable increase and pitch . . . at what speed is it safe to deploy 40% of down canard to act as brakes with out the pitch up?

What TX's are you too using and what is your configuration?

Alisdair fancy bumping into you, along way from the water plane forums arnt we

Siddus74

siddus74

What does everybody else run as far as RX power / battery choice and servo choice? 4.8v or 6V.

A little off topic but my Boomer is having 2.4ghz AR7000 with a S3010 on the elevator some S9202 of the ailerons and some 5KG 5010Towerpros on the nose wheel and flap (im making use of the best I have laying around), I have a Hobbywing 15amp UBEC (cheap but has worked faultlessly in a topflight DC3) running @ 6V with a 2S1P 1850Mah 25C lipo for power - Im new to all the jet stuff but some of the local jet boys have what seems a rediculous amount of equipment installed, fail safe for this and that, something called a powerbox? etc etc . . . these pair of toys cost 1K each which for what they are I do not is expensive but I could easilty load another £300 quid into then for radio etc . . . then they cease to be fun and start costing . . . is it all necessary?

The Reaper has 35Mhz SPCM and rediculously spec'd servo's should I be looking to change it for some good old S3010's and put 2.4 running 6v in this one? where do you boys call it enough?

Siddus74

BaldEagel

Siddas

The deployment of the canard as a brake only works on an all flying canard, don't try it with the Reaper unless you have installed and all flying canard as I did see top of page.

I use two 2 cell A123's into two Fromeco Kodiak switches and plugged straight into the Rx, no powerboxes, no regulators, just two batteries, I also use a 3 cell A123 to power the ECU, can't get much simpler.

Mike

siddus74

Mike,

Sounds good, please can you share some further details? How does that work?

Scott.

BaldEagel

Scott

By your question I assume you do not know about A123 batteries, they are Lithium Nano Phosphate or LiFe, they are 3.3volts per cell and need a special charging programme, or a special charger which only charges at a maximum of 3.6volts, they can be charged at 10amps yes that's right 10amps and only come in capacities of 2300Mah or 1100Mah, there are some rip off ones out there called P04, but do not be fooled only genuine A123's are worth using.

The Fromeco Kodiak switch is a fail on switch with a Digital read out of Mah used during the time it is switched on, cumalative until reset.

If you want to know anymore just ask.

Mike

dw_crash

My Feedback: (6)

Gents,

I use a five cell nicad pack for one reason.....lead length. In my jets, I have lots of extensions that are 24" to 48" long. To get the current to these servos, you need some volts to push the power there. I don't want the servos to run out of power due to the voltage drop do to lead lenght. So, starting at a higher voltage give more available to teh servos under load through these long extensions.

Dave

siddus74

Mike,

Fail on switch? How do these switches help over normal ones? Do you have 2 power supplies to your RX? I presume you are usnig spekrum then on a 7.2v supply? What voltage is the radio equipment running on and how is it regulated?

Appologies for so many questions but you seem to have all the gen . . .

Any links to the the equipment you are employing would be very much appreciated.

Scott

BaldEagel

Forgot one thing the A123's maintain their voltage for approx 2000Mah of there 2300Mah capacity, then they almost switch off, so charging them needs to be done early rather than late.

Mike

BaldEagel

A fail on switch is just what it says, when you switch it off it is enabled, if the switch has a mechanical or electrical failier it reverts to on, so much safer than the ordianary switch you get with most sets of gear, google Fromeco and you can see everything they do.

I am a Futaba man even though I have a Spektrum set, I would not use it in my Jets due to its propencity to switch itself off if the battery gets low.

A two cell A123 is nominally 6.6volts so no need for regulators as a five cell Nimh is nominally 7.2volts off the charger, so the A123' are just plugged straight into the Rx, when I get back into the workshop I will post a pic of the inside of my Elan which will give you the idea.

Mike

BaldEagel

Link to A123 systems: http://www.a123systems.com/

Link to Fromeco Kodiak switch: http://www.fromeco.org/Products/04FR...0/Default.aspx

Mike

Wayne22

My Feedback: (2)

It is a very low tech jet - keep it simple! Nicads work just fine..I used 4.8 volts, (but knowing what I know now, would go 6 volts with a regulator.) It is not a fast jet (the merlin 160 example excepted) and there is no need for a lot of control movement, so expensive digital servos are not needed on this platform - though obviously you want to use what you have. They will not be working very hard......

dw_crash

My Feedback: (6)

Wayne,

Well put,

Dave

BaldEagel

Although I agree on the concept of it being a low tech jet, IMO its purpose in life is to introduce those who have them how to set up and operate a jet, or as a winter hack, it therefore is the perfect platform to experiment with all the gizmose you may want to put into something more high tech and prove the system, but then you can just use it as a simple airframe with no regulators or powerboxes or anything fancy and fixed gear, just to keep the whole thing easy to operate.

Personally I would never operate a jet without Digital servo's its not the amount of movement, but the holding power under load that is the deciding factor, with the potential of loading the servo's at high speed, Digital servo's are a safety factor I would not ignor.

Mike

EDIT: Nicads are not available anymore in the UK, and the new chemistry in Nimh batteries make them now suspect as well.

dw_crash

My Feedback: (6)

Baldeagle,

That is why I have basic digitals on elevator and left the reasonable analog Futabas on the Aerilons. If a an airelon servo sags, the roll just slow. with the elevator....you hit the ground. So I would not disagree with you. WIth a JJ1400 in it, it flies at a modest pace. maybe 150 km an hour. Roll rate is quite slow. That huge wing has lots of drag when you roll. a fast roll bleds off a lot of speed quickly. So I slow roll it.

Good thoughts you bring up,
Dave

alasdair

Baldeagle,
I started with 60-70 degrees of up on the canards, which gives pure drag with little or no pitch effect.

Later I reasoned that reducing to 40 degrees will give plenty of drag, plus a lift boost at the nose. The lift on the stalled foreplane was then excessive, giving too much nose up pitch, so I mixed in some down on the elevons to compensate (a degree or two is enough) which gives extra lift on the wing as well. It must reduce stalling speed by a knot or two. It makes little practical difference, it just seemed logical.

Siddus74,
The full size typhoon uses down canard as an airbrake after landing, but not in the air. On the approach you really want enough UP canard to make it fully stalled. As it deploys it goes from normal flying angle through maximum lift (which gives a transient nose up effect) then into the stalled condition with high drag.
If you go-around (overshoot), when you cancel the airbrake function it again passes through maximum lift, giving a useful nose up pitch, on its way to normal flying angle.

The canard on the Rookie, or Reaper or Saab Gripen for that matter is small compared to the wing. I found that the wing is dominant, and much more powerful than the canard. One click of trim on the elevon needed several degrees of opposite trim on the canard to counteract.

Scott,
Did you see my Lochstar at Colwick? I have canards that I use as airbrake on it too and they make a big difference (see attached).
Jet version coming next year.

BaldEagel

I suppose it accords to what you are trying to achive with the pitch up on the Canard, masses of drag to slow the thing down and bring it down, or just trying to control the speed and angle of decent, I fly from a restricted length patch so I need a good rate of decent and slow touch down, this is more easily achived with a lot of drag i.e. Canard at 80 deg or so, the bottom brake does not seem to make a lot of difference once the Canard is deployed, but to reitreate this is with a full flying Canard, just in case you guys with the Reaper and a standard canard are reading this.

Mike