jet flight

[noclassmac1972]

Thankyou for all your comments. The feel of flying a jet is just awesome. Just one note in NZ we use 65 foot lines and the fuel is unrestricted so once i get the plane trimed properly I will be using 50% nitro 50%propylene oxide. It would be nice to do over 200mph. I am quite comfortable flying at 1.1 secs per lap so it shouldnt be a problem

Jerry with The US rules you can nominate a flyer so as long as the model is yours and you are part of the starting team then the flight goes under your name.. I think the pilot is refered as the whipper.

Hear in NZ we are trying to introduce that law as their are a number of older flyers who cant keep up any more but love to still compete not just in the jet class.

Better get the models ready for tomorow

Cheers
Robert Bolton

[noclassmac1972]

Here are a couple of pictures of the pressure nipple arrangement on the Bailey fastjet head just so people have an idea on how it works..

Cheers
Robert Bolton

[noclassmac1972]

Hole on the face plate 30 thou If I remember rightly

[noclassmac1972]

pressure nipple in the head

[ed knesl]

Here is a pic of the model

Robert Bolton

Robert,

You model is fantastic - would you post some dimensions ?

I was planning something similar - I would eliminate the outer wing and increase a bit inboard wing chord to reduce drag while maintaining lift.

Your model is very easthetic creation - I have to admit, the outboard
swept wing makes it pretty racy looking.
What is the fuselage/tank made of ?
How long does your flight usualy last ? I remember it used to be under
one minute for racing. Hard work.

Robert has created the REAL PULSE JET FORUM contribution !
" Today tidbits and many others " unfortunately woun't fly.

Jets are for flying machines !

Ed

[Mike Everman]

Thanks for the photos! Beautiful stuff.

[ed knesl]

I just thought I would load up a file of a control line jet flight just so people who havent seen one before could get the idea of it. The motor is a bailey fast jet and the flying site is in new plymouth new zealand

Hope you all enjoy
Robert Bolton

I watched it at least 50 times and enjoyed and enjoyed.
I flu lot of C/L, however not PJ, always watched them. You show a great pilotage, on the first round locked on 1 meter level and from that on, it was rock solid, as I watched the tip of the fence pole passage.

Great ! Congratulations.

Ed

[Mike Everman]

Considering the strength it takes to keep that plane pulled in, why can't there be some rudder applied, maybe actuated by the cetrifugal force itself? If the cable horn was on a stiff spring and it's movement made a yaw correction, you could limit the CF to 5Kg or so...
I'm sure that's been tried and I can imagine that if it's not adequately damped you could get a wild yaw oscillation.

[Graham C. Williams]

Dear Mike.
We used to do that with the hydroplanes, set them up so that with the line drag (it arcs back behind the model) the model is slightly nose-in. I'm sure the aircraft models are set-up the same way. A lot of the force felt at the centre is the line drag.
I once set-up a model with too much nose-in, it got up to about 60mph shot across a cord of the circle, the line dragging in the water and the whole lot did a Bluebird.

Graham.

[Mark]

Thanks for posting all that stuff Robert. I keep coming up with questions though. Is the cowling held on by the clamp, I don't see enough threading or a screw? When you mentioned that the fast jet will not run without the pressure tap, how does the pressure feed the fuel into the engine, is the metering jet similar to the sport jet? How many little holes? Could you explain how the fuel tank is set up to use the pressure tap. Is the tank just a hollow chamber of sorts or what tricks are in there?
Mark

[ed knesl]

Considering the strength it takes to keep that plane pulled in, why can't there be some rudder applied, maybe actuated by the cetrifugal force itself? If the cable horn was on a stiff spring and it's movement made a yaw correction, you could limit the CF to 5Kg or so...
I'm sure that's been tried and I can imagine that if it's not adequately damped you could get a wild yaw oscillation.

You don't hold the whole CF force at all. You have it in hands just on
take off, than control handle gets slipped into pylon fork and after that,
you just run around the pole. Not an easy task either. This pole has two functions - one is obviously CF and second to prevent "pulling" forward the line to achieve higher speed ( racing rules ).

Also any rudder means drag and opposite fixed rudder is often installed on
slower models to keep the lines fully stretched for good conrtol.

Besides all that - I hope that most of you watched that video.
These pulse jets crafts are fearsome speed demons - they usualy fly
them in complete enclosure from heavy duty chain link fence, min.
10 - 15 ft high to protect life and properties nearby. Therse things get
loose more often than you think. Lines simply get ripped out of bell
crank, or whole ball crank goes from the fuselage.

Free flying plane ( R/C) is going to be even lot faster than C/L.
Speeds must be expected over 250 MPH ! In no time the plane is out
of sight and out of radio range.
Dangerous stuff !

Putting PJ on gocart is pure lunacy unless gets tested at Bonevill or
similar endless super leveled plain of salt lake.
The floor pan on ground effect is like lifting body and there is not much
to keep the vehicle on the ground after certain speed is achieved.
( lots of spoilers would be needed and the chute ).

I say this to bring these issues for everybody's awearness. This is serious
stuff.

Ed

[noclassmac1972]

We were having a good conversation about the safety of jet flights today out at the flying site. In all we thought that the jets are safer as none of us have had any cuts or burns the only real danger is the noise. But a good set of earplugs or muffs fixes that. The models are all pull tested before each flight and if any signs of damage or weakness then they arent allowed to fly. Its all comensence.

Today was a good day flying in all we had 12 flights between 4 people. And a lot more knowledge has been gained as every time we go out we learn something new..

On the pull you just get used to it. I dont use a cross bar as i find it restricts some control so the whole pull is on me. The others with their planes use the crossbar but their is a slight strength difference between myself and Don, Andrew and Brendan.

I am thrilled with all the replies keep it going

Cheers
Robert Bolton

[dynajetjerry]

Hi, Guys,

I've been rereading this thread and decided to insert a few more comments.

Yes, it is permissable for "builder of the model" rule to be fulfilled when the builder is a contributing part of the flying team; he/she does not have to actually fly the model. In fact, here in the middle-eastern U. S., a speed group is often composed of 5 or 6 models in competition but only 1 or 2 fliers! I am no longer ambitious or knowledgable enough to design and build competition jet models. I used to do such things for fun and now, most truly successful competition modelers work so hard that I am reluctant to insert my playing around into their activities.

AMA C/L Speed competition permits the use of Monoline(R) for flying because a single wire presents much less drag than two, even though it needs to be 50% larger than each of the pair. Control is achieved by twisting the wire and, thereby, turning a control unit in the model. I once watched Dale Kirn fly a 3 foot model, powered by a K&B .45, on a 150 foot line! He had full control, even when the line sagged almost onto the ground. As this fully demonstrated, line tension was not a factor in retaining control, unlike the two-line system.

The only restrictions on pulsejets for AMA Speed events is that the minimum cross-section of the tailpipe not exceed 1.25 in. and all of them must burn methanol/prop oxide fuels, 80/20. That minimum can be extremely short and the remainder of the exhaust pipe can be as large as desired, without exceeding the limit.

The Bailey Fastjet is a cleaned up version of Charlie Davis' Awesome Warrior of 25 years ago. Mike Hoyt (who proved the value of his sidewinder design for unpressurized pulsejets,) improved Charlie's creation a little, though both used a D-J pipe assembly. He called his version the Raven. I have both of them.

Jerry

[noclassmac1972]

I will have to correct you jerry in the fact that hoyt produced the raven engine first and charlie davis made a few minor changes to this engine and had many victories with it. Charlie then worked with earl baily to produce the awesome warrior which is a copy of charlies modified rave head with the baily tail pipe. The time and development that was put into these engines must of been fun and frustrating at the same time.

One class that is run is the sport jet class which is an unifical AMA event.

This uses un modified dyna jets or baily sport jets with a basic 2 line with external controls. They use 22thou? 65 foot? lines with the 20% propylene oxide 80% methanol fuel. This event can be as serious and as fast as you want it too be but the main aim is to get people flying. Speeds range from 110 - 150mph

I do recomend this class to anybody who is interested in starting out

Cheers
Robert Bolton

[dynajetjerry]

Robert,

You may very well be correct in that Mike Hoyt was first with his Raven. However, I have a copy of an early Speed Times paper that contains a letter from Charlie that seems to indicate his modification was improved on by Mike and Earl tweaked both designs for his production. I don't understand this.

Perhaps you can clarify another issue I find to be confusing: Though Sportjet is an unofficial AMA event, the 1.25 sq. in. and 80/20 fuel rules still apply. If Earl's expansion of the rear part of his tailpipes improve performance, why are they permitted in Sportjet in competition with unmodified D-J and similar pipes? It seems to me they may pose an unfair advantage. Glenn Lee and a few others have no opinions on this subject. (I will see some of those guys at Dayton next month.)

Jerry