Just saw a few snaps of the Javelin on Airliners.net

With the inclusion of (heavy) ejection seats for military training roles, will the overall performance of the jet be reduced?

Will provision be made for armaments eg hardpoints or is its entended purpose for filght training only..?

In biz jet configuration what will the luggage capacity be..?

Were two engines selected for training requirements or in flight redundancy? Usually means twice the maintenance...seems overkill for such a small jet..

Thanks
Chavez

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Originally posted by MrChavez:
Just saw a few snaps of the Javelin on Airliners.net

With the inclusion of (heavy) ejection seats for military training roles, will the overall performance of the jet be reduced?

Negative. The expected performance is based on the ultimate installation of two Martin Baker Mk16L ejection seats. The prototype has 1 installed...and its very much a fully-operational seat.

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Will provision be made for armaments eg hardpoints or is its entended purpose for filght training only..?

Very likely. There are plans for both a light interceptor role (for homeland defense of the US against any more hijacked airliners which would be used as missiles in the future.), and as a UCAV. There are no plans that I am aware of to make it a capable defender against military aircraft. The Javelin Mk20 is the military version, and a good portion of the program is being funded by IAI.

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In biz jet configuration what will the luggage capacity be..?

Not sure exactly, but it will be adequate for most short-range travel. There is an impressive bank of CVRs and FDRs installed in that space at the moment.

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Were two engines selected for training requirements or in flight redundancy? Usually means twice the maintenance...seems overkill for such a small jet..

A little bit of both, actually. Not to mention the performance of the aircraft. It is currently slated to have a Mach 0.92 design speed. Williams FJ33s are becoming the engine of choice of many new jet manufacturers...Williams is probably a good place for investors to put some of their money. I have 100% faith in the Javelin program, as it is being run by former military test pilots and actual aeronautical engineers. I can't say the same for some of the other manufacturers...one of which is being run by software engineers. That "other" company actually tried to get me to certify one of their testbeds for IFR flight, when they apparently decided that pitot heat wasn't necessary. LOL. I had to tell them, "I appreciate all of your hard work, but I'm afraid you're going to have to tear that wing open again and make it happen if you want my signature...otherwise you're limited to day VFR."

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Thanks
Chavez

No problem, Mr. Chavez. I LOVE talking about the Javelin. Hopefully I'll have more video and pics to post soon. The weather is good and the L-39 is back to making daily proficiency maintenance flights.

While we're at it..

What part of the javelin program are you involved with?
I seem to remember an old post where you mentioned flight control software certification...is this right?

Is the javelin fly-by-wire or are it flight controls hydraulic?

If fly-by-wire what sort of computer systems do modern aircraft use. Are they custom built from the ground up or are they off the shelf items that can be programmed differently depending on the aircraft?

From last post > Surely a little ice on a pitot wouldn't effect anything ("whoop whoop pull up")

Thanks
Chavez

Nope, I have been involved with flight instrumentation and ATC transponder system certification on the Javelin. The Javelin, in its current incarnation is a cable/pulley controlled aircraft...no FCS or hydraulics involved in flight controls.

As for ice on the pitot...yup...you are exactly right. The pitot system could EASILY seal off with ice, often giving fatally high airspeed indications. Season doesn't matter as much as many would think...I had a Cherokee 6 with a dead DG come in about three weeks ago...it had AT LEAST 100 pounds of ice on the ground underneath its leading edges. The pilot was very happy to be alive (along with his wife, and his dad), and happy that he still found the airport. Ice can ruin your whole day around here.

Iguana, quick question. The top speed you are shooting for, is that a maximum speed at high altitude or will it have a similarly high speed at low altitude?

That's a performance maximum...and its at altitude. Not sure how well the pretty, civilian paint jobs would hold up to that at lower altitudes. But, the tests are only beginning...and its a slow process. The current ADCs in the Javelin prototype top out at 250 KIAS. BTW...the Javelin has made 3 test flights so far.

I got a bit confused, ice in the pitot tube cause high speed to be read? I would think it would or at least could read zero air speed too. At least in MFS it reads zero causing the auto throttle to rev up to maximum.

Amazing how difficult it get with no IAS reading, ... I guess they are lucky these days that I suspect GPS could be another source of a rough TAS reading.

The problem with ice in the pitot tube is that it often seals off the pitot system during flight. It holds the pressure that was in the system at the exact moment it iced up. Thus the airspeed will only change with an increase or reduction in altitude. A 1000' change in altitude is approximately equal to a 10 knot change in airspeed, since the static system is connected to the case of the ASI. So, the aircraft could be near stall speed, but show a much higher IAS if the pitot system becomes blocked.

Anyway, are there any hi-res pictures of the javelin's first flight or any movies out there?

There is high definition video taken in both the Javelin and L-39 cockpits during the first flight. I've been promised a copy of it, but its been a while since I asked my buddy there about it. I'll see if I can rattle his cage a little.

allright! write a letter to Microsoft

quote:

Originally posted by IguanaKing:
The problem with ice in the pitot tube is that it often seals off the pitot system during flight. It holds the pressure that was in the system at the exact moment it iced up. Thus the airspeed will only change with an increase or reduction in altitude. A 1000' change in altitude is approximately equal to a 10 knot change in airspeed, since the static system is connected to the case of the ASI. So, the aircraft could be near stall speed, but show a much higher IAS if the pitot system becomes blocked.

Also, isn't there a "static" (ambient) air port in the fuselage of the aircraft? My understanding is the avionics reads the differential pressure between the static port and the pitot to determine IAS and altitude. Or am I way off-base here?

Hey Iguana, I know it's not your turf, but could you please statisfy my ejection seat fetish by making some pics, just when you get the opportunity to do, a side view, and a front one. But only if it won't get you into any trouble, or if it is too much of a hassle, don't bother then.
The Mk-16L is something like 63.4 kg in weight :P, while retaining the low speed performance of heavier seats.
Actually that 'performance retainment' is becoming a problem because of the low weight of the seat the instantaneous acceleration forces during the rocket stage are quite high, just ask the lucky Russian bastards that got to use the K-36 3.5LT when ejecting from their bugged Yak-130 a few month ago, though most of their injuries came from the canopy shards.
On the yak-130 (aka Little Piggy in my vocabulary) there are canopy breakers on teh seat, and two prototypes, and production medels have also MDC to shatter the canopy, apparently that isn't working too well right now. I think though that the injuries occured because they ejected out of a flat spin, as per ground command, don't sure on how to interpret that, it may have been an invuluntary ejection initiated by datalink, because the boys on the ground didn't want to loose another 2 test pilots
And yes, it was a FCS bug that caused the loss of control.

No FCS on the Jav eh? Lucky test pilots.

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Originally posted by SoD_Stitch:

quote:

Originally posted by IguanaKing:
The problem with ice in the pitot tube is that it often seals off the pitot system during flight. It holds the pressure that was in the system at the exact moment it iced up. Thus the airspeed will only change with an increase or reduction in altitude. A 1000' change in altitude is approximately equal to a 10 knot change in airspeed, since the static system is connected to the case of the ASI. So, the aircraft could be near stall speed, but show a much higher IAS if the pitot system becomes blocked.

Also, isn't there a "static" (ambient) air port in the fuselage of the aircraft? My understanding is the avionics reads the differential pressure between the static port and the pitot to determine IAS and altitude. Or am I way off-base here?

Actually, that depends on a few factors. If you are talking about an aircraft which has an SDCM (Static Defect Correction Module), then you are absolutely correct. Pitot pressure AND static pressure are used to determine IAS AND altitude. The SDCM needs to know the speed of the air moving across the static ports in order to give an accurate altitude. However, this doesn't apply to aircraft which don't use an SDCM. In the case of an aircraft such as that, it is static pressure only which is fed to the altimeter. But, both pitot and static pressure are still used to determine IAS in an aircraft without SDCM.

On the Javelin, the static ports are actually located right on the sides of the pitot mast.

Force, no dice on the ejection seat pics. The only picture I have been able to get is of the mounted seat, through the windscreen. Nobody but the test pilots, crew chief, and pyro guys are allowed near the aircraft when the seat is mounted and the canopy is up. No other personnel are allowed in the area during the removal and transport of the seat, its for safety reasons...just in case. Sorry man.

NP, better that than some curious cleaner hitting the initiator.