RunRyder RC
WATCH
 3 pages [ <<    <     1      2     ( 3 )    >    >> ] 3770 views Post Reply
09-07-2006 11:36 AM  14 years ago
Yug

rrMaster

UK. Herts

MyPosts All Forum Topic
How do you calculate the amount of air the fan can shift ?Vegetable rights and Peace
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-07-2006 12:02 PM  14 years ago
ChristianM

rrVeteran

Oslo, Norway

MyPosts All Forum Topic
The calculation is one thing but coming up with some meaningful input data is not trivial on this system. The biggest uncertainties are:
  • The pump characteristic of the fan
  • The flow resistance in the system
  • and several other uncertainties
The only thing I can think of is to put on head loaders (instead of the main blades) and run the engine up to your operating RPM and use a hand held wind speed device to measure the velocity of the flow from the fan. You would have to take measurements at several locations around the head to get an average but this should give you an idea.

PS: Be careful if you do this and watch out for any rotating parts.

Christian
Burn fuel, be happy
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-07-2006 12:27 PM  14 years ago
Luckylandings

rrVeteran

Oregon USA

MyPosts All Forum Topic
Hey Guy? Couldn't you just use a screen from certain types of smoking utensils to cover the top of the carb and just band it with something?
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
09-07-2006 03:13 PM  14 years ago
Yug

rrMaster

UK. Herts

MyPosts All Forum Topic
The main reason why the snorkel stuff all came about was because the pinion gear was wearing quite rapidly in the bearing, and basically some of the particles were ending up in the engine and damaging it. The snorkel idea was a damage limitation exercise. Some time ago when the wear on the pinion wasn't too extensive but none the less, NOT a snug fit in the bearing, I refitted it with thick grease, and so far there hasn't been any further wear.
It's interesting how my XeroG has never suffered this problem, probably because it is such a rigid machine unlike the R50, where the flexability of the plastic probably flexed sufficiently to allow breaking the loctite bond between the pinion and bearing.
In light of this grease solution, and barring hot starts, I'm currently wondering whether to go back to the stock design, ie, no snorkel or filter. However, it would be interesting to further analyse the fan flow v snorkel v cooling efficiency. On the other hand, just shovel it all back together and go fly.

Luckylandings - the gauze you speak of is way too course.

ChristianM - I'm not at all comfortable with the use of head loaders. However a static bench test using a fan, shroud and dremmel may be a safe way of testing.
Vegetable rights and Peace
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-07-2006 06:01 PM  14 years ago
ChristianM

rrVeteran

Oslo, Norway

MyPosts All Forum Topic
I agree that there are some safety concerns with using the head loaders but you will not get an accurate reading without the engine in place since it provides resistance to the flow as it passes around the head.

Christian
Burn fuel, be happy
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
03-05-2007 03:49 AM  13 years ago
ProModeler

rrElite Veteran

Sanford, FL (Orlando area)

MyPosts All Forum Topic
Folks, a Raptor owner pointed me at this thread. A few comments if you don't mind. First off, yes you can certainly use a piece of panty hose. The fly in the ointment is it gets clogged so quickly it's not even funny - same thing with those Bruline filters. Hence, maintenance is a pain in the rear. Secondly, we too saw power improvements via fitting a snorkel. The reason is the air being drawn is is both approaching laminar flow (remember air being sucked into the Raptor's engine is practically tangent to the airflow the carb wants) plus, and this is a very improtant issue, the air is also significantly cooler. Cooler air is denser, and as we recall from high school chemistry, you can thereby mix more fuel to maintain the optimum air:fuel ratio. Because there's more fuel going into the engine you get more horsepower - no mystery there!

Anyway, eyeball this link to learn what I did when I developed my Pantera 50 helicopter's air filter system. I think you'll quickly see why an air filter was one of those things I felt was imperative to add to my latest design.

http://www.runryder.com/t329511p1/

Anyway, thank you for allowing me to explain what's going on.

My 2¢

John Beech
AMA # 47381
IRCHA #745
SHARE  PM  EMAIL  Attn:RR  Quote
WATCH
 3 pages [ <<    <     1      2     ( 3 )    >    >> ] 3770 views Post Reply
Print TOPIC

 15  Topic Subscribe

Wednesday, December 2 - 3:39 pm - Copyright © 2000-2020 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online