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Old Oct 20, 2013, 02:09 AM
guillows basher!!
Pittsburgh Allegheny, Pennsylvania, United States
Joined Feb 2004
962 Posts
Discussion
het f104 starfighter retract install

what is the thought on obstruction in the intake.....subject is a f-104 het 70mm,want to install undercarriage retracts ala f16 type but when retracted up the wheels will b in intake air flow? plan on arc 28-58-1 het fan 5s...........thanks
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Last edited by esb-help; Oct 22, 2013 at 04:31 AM. Reason: retitle
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Old Oct 20, 2013, 04:54 AM
guillows basher!!
Pittsburgh Allegheny, Pennsylvania, United States
Joined Feb 2004
962 Posts
ive decided to pull all ducting and start from scratch.........could have got it close but mains wouldve been too far behind cg........will end up having bare minimum fsa,will post pics and feel free to critique good or bad.
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Last edited by esb-help; Oct 20, 2013 at 05:51 AM. Reason: pics
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Old Oct 20, 2013, 06:15 AM
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D_FAST's Avatar
Denver CO
Joined Apr 2008
2,085 Posts
could you loose the ducting and add a lip to the shroud?
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Old Oct 20, 2013, 07:45 AM
guillows basher!!
Pittsburgh Allegheny, Pennsylvania, United States
Joined Feb 2004
962 Posts
Quote:
Originally Posted by D_FAST View Post
could you loose the ducting and add a lip to the shroud?
thats a thought....but the fan is at the back of airframe.....theres a bulk head that the wing spars r fastened to between intake and fan mount? could possibly move fan up to 1st bulk head but i need to worry about cg and batt placement.......hmmmmm,got me thinking!
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Last edited by esb-help; Oct 20, 2013 at 08:08 AM. Reason: pics
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Old Oct 20, 2013, 08:14 AM
guillows basher!!
Pittsburgh Allegheny, Pennsylvania, United States
Joined Feb 2004
962 Posts
pics
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Old Oct 20, 2013, 12:48 PM
deltas are cool
AIR SALLY's Avatar
Tehachapi ,CA.
Joined Apr 2006
20,957 Posts
i did this on a throp bros F-104 way back in the day ,you could make your own ducting and put bumps in the duct for the wheels ,and spread the ducts out at the bumps to try and keep the area constant.lot of work but ...
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Old Oct 21, 2013, 05:14 AM
guillows basher!!
Pittsburgh Allegheny, Pennsylvania, United States
Joined Feb 2004
962 Posts
Quote:
Originally Posted by AIR SALLY View Post
i did this on a throp bros F-104 way back in the day ,you could make your own ducting and put bumps in the duct for the wheels ,and spread the ducts out at the bumps to try and keep the area constant.lot of work but ...
yep thought about that but when retracted up the wheels r too close to the intake inlets that leads to a very abrubt angle to 1st bulkhead....almost cuts off half the intake area of both inletsi may just go byron style with parcial ducting.........will b some drag and wheels will dirty up the inlet flow but with gear down on takeoff the open doors will act like cheaters for ample enough air in then retracted up will close doors and have to rely on the dirty inlet for feeding the fan....not trying to brake the sound barrier just like to rog off the tarmac and pull gear up and land on the tarmac! also like the challenge of doing something differant....i did multiple searchs and cant find any 1 else who did retracts on the het f104 70mm
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Old Oct 21, 2013, 10:09 PM
deltas are cool
AIR SALLY's Avatar
Tehachapi ,CA.
Joined Apr 2006
20,957 Posts
i've never seen one with retracts...so yeah you might be the first.
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Old Oct 22, 2013, 04:46 AM
guillows basher!!
Pittsburgh Allegheny, Pennsylvania, United States
Joined Feb 2004
962 Posts
progress pics
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Old Oct 22, 2013, 07:38 PM
guillows basher!!
Pittsburgh Allegheny, Pennsylvania, United States
Joined Feb 2004
962 Posts
after i got rails in for retracts in order to spread the load on impact i came up with exspansion foam idea.........after foam exspands and drys i'm cutting some away then sand then possibly glass to fuse
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Old Oct 22, 2013, 08:40 PM
jean-claude Terrettaz
bidule's Avatar
Carp, Ontario, Canada
Joined Mar 2000
1,468 Posts
So much trouble , fly so well on bungee.
Good luck
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Old Oct 23, 2013, 01:35 AM
guillows basher!!
Pittsburgh Allegheny, Pennsylvania, United States
Joined Feb 2004
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Originally Posted by bidule View Post
So much trouble , fly so well on bungee.
Good luck
trouble too some.....enjoyment too others
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Old Oct 23, 2013, 05:56 AM
Registered User
Temperance MI (Toledo OH area)
Joined Apr 2007
33 Posts
Been thinking about doing this myself. JHH`s A7 has the same situation and I never had any performance problems with mine.
Hope this works out for you, I worked on the first A` and B`s in 1958 great aircraft!
CMSgt R. Driftmyer USAF Ret.
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Old Oct 23, 2013, 03:40 PM
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United Kingdom, England, Cobham
Joined Oct 2007
550 Posts
This is still one of my favourite 70mm EDF's, but you really need to keep the weight down. I'm on my second - the first had a heavy ARC with Wemo in aluminium shroud, on 6S. It was around 1500g without Lipos, flew well but was very difficult to land. Lasted about 10 flights and I got tired of repairing it. Second one is lighter and awesome. If you can keep your weight to below 1500g (or say 2Kg with Lipos) then you might be ok, but I don't see how that will be possible unless you are happy with flight times of under 2mins and overheated Lipos. Your duct mods will probably worsen performance further.

You are also going to have major balancing issues - it will be very nose-heavy with a retractable gear up front. How are you gong to counter that without adding even more weight?

Jacques
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Old Oct 23, 2013, 04:15 PM
guillows basher!!
Pittsburgh Allegheny, Pennsylvania, United States
Joined Feb 2004
962 Posts
Quote:
Originally Posted by Jacques.Eloff View Post
This is still one of my favourite 70mm EDF's, but you really need to keep the weight down. I'm on my second - the first had a heavy ARC with Wemo in aluminium shroud, on 6S. It was around 1500g without Lipos, flew well but was very difficult to land. Lasted about 10 flights and I got tired of repairing it. Second one is lighter and awesome. If you can keep your weight to below 1500g (or say 2Kg with Lipos) then you might be ok, but I don't see how that will be possible unless you are happy with flight times of under 2mins and overheated Lipos. Your duct mods will probably worsen performance further.

You are also going to have major balancing issues - it will be very nose-heavy with a retractable gear up front. How are you gong to counter that without adding even more weight?

Jacques
i wont add any more then 170g or 6 oz.and as far as nose heavy i can move the fan and motor back if needed,the ducting i removed was heavy as all hell and i'll replace with lighter........i am anxious about the dirty inlets but we'll c, my gear doors will b functional and will act like cheater inlets on take off then close them and i have a sealed duct inlet. my mistake 220g is what im adding with tri gear and mounting blocks.......mains r behind cg, probably when all said and done im projecting a total of 278g or 10oz added for gear install
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