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-   -   JHH Mirage fuel tank location? (http://www.rcuniverse.com/forum/rc-jets-120/1327225-jhh-mirage-fuel-tank-location.html)

dannost 12-04-2003 04:00 PM

JHH Mirage fuel tank location?
 
I'm building the JHH Mirage with the foam wing. I don't see any instructions or plan details for the fuel tank locations.
The kit came with 2 12oz tanks, but it doesn't seem there is room anywhere.
Anyone build one of these that can help me?

Also, should the air inlets be cut out to allow a starting belt to be put on the spinner?

geneh-RCU 12-04-2003 04:33 PM

RE: JHH Mirage fuel tank location?
 
I am building one as well but mine has the built up wing. The tanks in it go in two cutouts in the wing just behind where the fan would be. Not sure on the starting belt. I have been wondering how I would do that as well.

Good luck

Gene

MiragePilot 12-04-2003 08:31 PM

RE: JHH Mirage fuel tank location?
 
Gents,

I am also building a JHH Mirage, with the foam wing option.

You can use the 11oz Sullivan DF saddle tanks, placed on each side of the inlet (between the inlet and fuselage side), forward of the fan. I am using this setup and can verify that the two tanks fit with no issues. I recommend that you also make use of a small hopper tank, plumbed downstream of the 2 saddle tanks. You can place the hopper tank on the side of the fan/thrust tube.

Finally, don't cut the inlet for the belt starter access. You should call JHH and order the updated, area-ruled inlets for the Mirage... which are set up for starter probe access for starting. Your Mirage will be a MUCH better performer with the updated inlets.

Regards,
Peter

Thud_Driver 12-04-2003 09:08 PM

RE: JHH Mirage fuel tank location?
 
What MiragePilot said also worked for me for a fuel system. Mine was a very old kit and I used a starter probe down the left inlet which worked just fine. Both the JMP or BVM probes work for Dynamax or Ramtec. Don't know about Turbax.

dannost 12-04-2003 11:33 PM

RE: JHH Mirage fuel tank location?
 
It is a new kit and has the hi-tech inlets. But it also came with the starter belt, which is why I was confused. It looks like if you had a long enough probe, you could remove the canopy to get in. The inlets are enclosed all the way to the fan, so I can't use a probe there.

I'm really wondering why none of this is described in the plans or instructions

MiragePilot 12-05-2003 01:12 PM

RE: JHH Mirage fuel tank location?
 
If you have the "hi-tech" inlet, then you would use a starter probe to start the engine. You remove the canopy and engage the spinner bolt directly. Hang the belt on the wall for your next RC boat project:-)

THe JHH Mirage kit has been around for 20-25yrs and has been through several upgrades/modifictions over the years. Unfortunately, the plans and instructions contain a lot of the older/legacy info which is often obsolete for the "ugraded" kit versions. This tends to lead to some confsion for DF jet builders who are not "well versed in the art", so to speak.

My advice it that if you have any questions/confusion, just give Larry a call and he will get you squared away.

Regards,
Peter

balsa4cat 12-06-2003 12:17 PM

RE: JHH Mirage fuel tank location?
 
Hold It !
If the fule tanks are forward of the fan, you will have a CG shifting rearward as the fuel is burning off. In a Delta wing that is CG sensitive already, that can alter flight characteristics dramatically.
What or how has Larry Wolfe handles this situation ?
Sarting wand is the way to go on ducted fans. However I recomend that you put tennis racket handle tape on the sleeve bearing and use a dusting of graphite on the rod/sleeve bearing.

Thud_Driver 12-06-2003 01:59 PM

RE: JHH Mirage fuel tank location?
 
Quote:

ORIGINAL: balsa4cat

Hold It !
If the fule tanks are forward of the fan, you will have a CG shifting rearward as the fuel is burning off. In a Delta wing that is CG sensitive already, that can alter flight characteristics dramatically.

You balance with empty tanks, so you start "slightly" nose heavy, and the tanks aren't that far forward of the Cg. It wasn't a problem, largely unnoticeable, except maybe for elevon throw on takeoff.

Rider-60 12-06-2003 03:09 PM

RE: JHH Mirage fuel tank location?
 
Hi all,

I just flew my JHH Mirage yesterday. I've converted it to Turbine power ( ArtesJF50 Bee) after many years of D/F power.
I have one and a half liter about at the same location as the original D/F design, so CG shifting is not really a problem, deltas are really forgiving and not sensitive about CG location.
So go like it is shown on the plans with the tanks in the wing or put two saddle tanks each side of the intake .
You will be pleased with this plane which handles very well.

dannost 12-06-2003 06:12 PM

RE: JHH Mirage fuel tank location?
 
Thanks for all the help. I finally talked to Larry and he thought the saddle tanks would work. In fact I ordered from him right then.

You are right, Peter, there are a lot of things contradicting in the plans and instructions. They should really be updated. My foam wing did not even match the shape on the plans, it was 1 1/4" wider with a different leading edge angle. I do love those inlets though. Everything fits pretty well. Can't wait to fly it this spring.

razorice79 05-25-2004 04:27 PM

RE: JHH Mirage fuel tank location?
 
I know this thread is very old but, I have a few questions about the JHH mirage... I have an older kit with a K&B FIRE & turbax 1 it has 2 8oz tanks in the wings.. I've attempted to fly it with that old k&b, and was very disappointed because it just didnt have enough power to make this jet fly good.. I think my approx. dry weight is around 10 pounds.. Ive just purchased a OS 91 w/ ramtec fan unit.. and upgraded my tanks to two 11oz tanks.. will these tanks be good enough to get 10mins+ flight time with the new os91? and has anyone ever put an os91 in one of these how does it fly? thanks for the info.. wish me luck!

-Ron M.

Thud_Driver 05-25-2004 04:41 PM

RE: JHH Mirage fuel tank location?
 
You won't get 10 min. More like 6, maybe 7 with reserve. It'll fly fine on the OS.91 I flew mine variously with a Dynamax/OS .65, .77 or .91 and Ramtec/OS .91. You'll have to adjust the fan mounting for the Ramtec and get a new cap for the duct above the engine. I liked the Ramtec/OS.91 best. At the end, I think mine was around 11.5-12 pounds dry. If you have the cheater hole in the bottom, you can cover it up for the Ramtec/OS.

razorice79 05-25-2004 05:51 PM

RE: JHH Mirage fuel tank location?
 
Ive heard of people talking about adding a third tank or hopper tank, and mounting it by the fan/engine.. Can i do that? is a hopper tank a special tank or is it just a regualt tank with the clunk? I was gonna just make a new cap out of fibreglass sheet..never done it but shouldnt be that hard.. I do have that cheater hole on the bottom, do I need to cover it up? or does it really accept performance? if it will benefit more performance I will not hesiated to cover it.. i guess some balsa sheet will work for that.. did you have to add weight to the nose after installing that os91? Im sure I will... thanks again..

-Ron

Thud_Driver 05-25-2004 08:35 PM

RE: JHH Mirage fuel tank location?
 
You should use a hopper. A 1, 2 or even 4 oz oval tank tank. Whatever fits. You can use a clunk but a brass tube to the center is normal. The hopper should be at or near carb level near the fan but it can elsewhere. It's there to keep the flow even to the engine.

You don't have to cover the cheater hole but it will give some minor pitching effect with power. I didn't notice too much of a performance increase, but there certainly wasn't a decrease. Covering it will go a long way towards keeping dirt and rocks from hitting your fan blades. Pitch control felt different afterwards but it would be hard to quantify the difference. All the OS engines weighed about the same so there was no Cg shift when I changed out engines or fans.

Make sure you have a nose up angle when on the gear. If you don't, or if it's nose heavy, it will take quite a lot of up elevator to get off and afterwards you'll need way less for normal flight.

razorice79 05-25-2004 08:50 PM

RE: JHH Mirage fuel tank location?
 
YOU THE MAN! thanks for all your info.. let you know how it turn out..

-Ron

CARS II 05-26-2004 01:23 AM

RE: JHH Mirage fuel tank location?
 
1 Attachment(s)
All very good information here, this guys know what they are talking about.

Happy Flying.

CARS II

CARS II 05-26-2004 01:31 AM

RE: JHH Mirage fuel tank location?
 
1 Attachment(s)
One more :).

CARS II

razorice79 05-26-2004 02:01 AM

RE: JHH Mirage fuel tank location?
 
kool jet!!!! i'll have to take some pics of my mirage the next time i go out to fly.. and post them on here..


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