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Sep 16, 2013, 12:02 PM
A-4 nut!!
skyhawk's Avatar
jetjock50 - No apparently you miss the point.....but whatever.
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Sep 16, 2013, 01:38 PM
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jetjock50's Avatar

not meant as a argument


I agree that the rear radius to the 5inch diameter is pretty tight, and as previously stated there is room between the stock former and my plug to soften that radius and I could oval the opening and laminate the former to maintain integrity., and allow further straightening of that radius. As can be seen in Pauls picture his front fan lip is even with former inside his ducting, as would mine. Thus my only debate is wether or not pauls ducting is superior to my proposed ducting. And it really doesn't matter as I can alter it still at this point. One of the objectives in mounting the fan and motor at the shown location, is relating to balancing the plane without adding unwanted weight. As I don't want to have excessively long leads from the 14s batteries to the fan and speed controller.
As relating to the originator of this post, since you already have the two 90mm
fan units and speed contollers, and after seeing the performance of that mig in the video, I too would probably go that way with the twin fans.
Sep 16, 2013, 02:34 PM
A-4 nut!!
skyhawk's Avatar
ok.
Sep 18, 2013, 12:46 PM
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jetjock50's Avatar

reworked inlet plug


I have cut my plug in two and added a 11/2 inch section in the middle and reshaped it substantially straightening the rear curve. and it is only barely touching the main former. It is only rough sanded and most likely will not touch at all once I smooth it out. I am pondering, if the linlet should be attached to the former, for support anyway? Since the original Byron fan was mounted there, I see no reason not to. I would most likely install some ply tabs to it and then attach them to the former with some screws. I will add a photo after I have it sanded down. Does anyone have the actual outside diameter of the front of the Dynamax fan?
Roger
Sep 18, 2013, 12:52 PM
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Quote:
Originally Posted by jetjock50
i have cut my plug in two and added a 11/2 inch section in the middle and reshaped it substantially straightening the rear curve. And it is only barely touching the main former. It is only rough sanded and most likely will not touch at all once i smooth it out. I am pondering, if the linlet should be attached to the former, for support anyway? Since the original byron fan was mounted there, i see no reason not to. I would most likely install some ply tabs to it and then attach them to the former with some screws. I will add a photo after i have it sanded down. Does anyone have the actual outside diameter of the front of the dynamax fan?
Roger
5.26"
Sep 23, 2013, 04:46 PM
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jetjock50's Avatar

new inlet shape


ok, still need to fill and final sand but here are some pics of reshaped plug for my inlet duct. Should be substantially better.
Sep 23, 2013, 05:18 PM
Dont forget the velcro straps
corsair nut's Avatar
looks like theres enough inlet area, there shouldnt be too many issues with that. its sharp radius, but ive seen worse, and it worked good, so i think youll be fine. is it optimal...not really, but should work well givin what apears to be a exess of inlet area.
Sep 23, 2013, 09:56 PM
Registered User
JetJock

At the risk of sticking my nose in here...
These guys know what they're talking about.

Look at this picture from the other conversion thread
https://www.rcgroups.com/forums/show...1127579&page=2

Then compare it to this pic of yours
https://www.rcgroups.com/forums/show...1993954&page=3
You fans may be in the same place, but the inlet ducting shapes vary greatly.
Yours is "U" shaped, like the trap on a faucet. The other is more of a "V" or "Y" shape.

Anybody know if you can paste the two pics side by side instead of the links?

Jim
Last edited by JimF; Sep 23, 2013 at 10:06 PM. Reason: Greater clarity
Sep 23, 2013, 11:23 PM
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jetjock50's Avatar

unbelievable!!!


Given the distance between the inlets, the distance to the fan , the offset of the centerline of the fan and the thrust line for the plane. There is no way the other guys inlet is any straighter than mine. And his, certainly does not have nearly the volume of air as mine. So I will take my 40 plus years of fabricating and installing duct work, finish this inlet and install it. My duct calculator does not lie.
I have made my concession to all of the gurus. If it does not work, I will be the first to admit it. By the way did the other guys work?? I can not find any where, any thing say that the plane was completed and flown. Just asking????









s
Sep 24, 2013, 08:49 AM
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jetjock50's Avatar

private message from Paul


Yes, that Paul, with the other plane mentioned in this discussion.
Yes it has been test flown, but not entirely done.
Yes he feels my inlet is fine. but wants to change his outlet/tailpipe ducting . As he feels too much efflux is being lost with the Byron tailpiece. He also said that he wants to strengthen the stab assy. Which I have already addressed with the Jet Legend stab mechanism
Jim, the pictures you referenced above clearly show the inlet with a much sharper radius into the fan. I do appreciate input, but I am not a rookie I have been building, and flying for 32 years including ducted fans and turbines.. I will process your input, check references and then do what I feel will work. I will never sacrifice strength in an airframe for any reason.
Last edited by jetjock50; Sep 24, 2013 at 08:56 AM. Reason: rechecked refernced photos
Sep 24, 2013, 12:21 PM
Dont forget the velcro straps
corsair nut's Avatar
for what its worth, i think the duct will work fine.

i know XPS made a dual exit pipe to use in the yellow F-15, something like that would do the trick in this puppy...
Sep 24, 2013, 04:56 PM
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Ok. Just commenting on what I see. From another angle they do look more similar than I thought. My bad. I was wrong.

Good luck.....
Sep 24, 2013, 09:21 PM
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jetjock50's Avatar

It's all good!!


Jim, this is all about sharing our thoughts and ideas and trying to build better planes. I am glad you joined in!!! After hearing from Paul and hearing that his inlet worked well, and he felt mine would be fine as well. It is time to move on to the tailpipe ducting. I am wondering if XPS made that tailpipe or got something from Yellow ac or maybe Aeroloft F-15???? Paul is thinking that the Yellow f18 single tailpipe might be the answer. He said he thought his plane kinda topped out at high speed due to the big Byron tailpipe. ??? So, I will try to mold up an intake while pondering that tailpipe .
Sep 24, 2013, 09:40 PM
Dont forget the velcro straps
corsair nut's Avatar
I believe it was xps designed and the plug was cnc cut...they used it in the yelliw single f15.
Sep 24, 2013, 10:34 PM
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jetjock50's Avatar

I will try Jim Drew


Lets see if we can get ahold of Mr Drew and get some info.


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