rotor blade droop

Ive seen a couple guys here recomend adding a little heat, not too much though. Never done it myself, im sure someone knows better.

thanks. this is my first try at a helo. would i use a heat gun or hair dryer? like i say, i've already primed and painted them before i realized they didn't look right. i was thinking about hot water, maybe?

humper491

thanks. this is my first try at a helo. would i use a heat gun or hair dryer? like i say, i've already primed and painted them before i realized they didn't look right. i was thinking about hot water, maybe?

I have never done any bending of rotor blades but you could try hot water, and bend it a little as its in the hot water to try and get a sag into it.  Or you can try the heat gun or hair dryer i would think both would work, heat gun you might get a little to much heat though but just quick exposure to it would work how ever ruining the paint.  But like i said i have never done any of the above so let me know how ya make out.  :)  Good luck!!!

hi.. got that problem bfore. learn it from here. a bent hacksaw blade is all you need. tie your unpainted blades one by one ang soak in boiling water for at least 20 secs.. droop depends on thr bent of the hacksaw blades. goodluck!!

I've yet to try this myself but I've heard of setting the rotor blade assembly upside down on a plate or shallow bowl and applying heat with a hair dryer.  As the plastic gets softer it will sink into the indentation of the plate or bowl but will not go too far since the bottom of the plate would stop it (that's why the bowl would need to be shallow).  Just be careful and apply the heat with the low setting on the hair dryer.

Legos!

I make a jig out of Legos to hold the blade assembly. You use the blocks to build a jig which supports the center of the rotor assemble up, then you set the rotor tips into or under lips made from blocks to hold them in the correct droop supporting the rotor between the center support and tip if/as necessary. Put the whole thing into a container and fill with hot water. Repeat as necessary until the blades hold their shape. You can also do each one individually if you want, just be sure to use the exact same jig for each.

roughseas

hi.. got that problem bfore. learn it from here. a bent hacksaw blade is all you need. tie your unpainted blades one by one ang soak in boiling water for at least 20 secs.. droop depends on thr bent of the hacksaw blades. goodluck!!

I agree 100%. This is the best & easist way to achieve realistic and consistent droop.

Get a hacksaw blade, bend it a little and secure a length of wire from the hole at one end to the hole at the other end. This will maintain a constant curve. Do your rotor blades one by one. Tape the rotor blade to the outer curvature and immerse in hot (near boiling) water for 20-30 seconds. Allow to cool (important) then remove and repeat with the next blade.

Ensure that each blade sits in the same location on the bent hacksaw blade just in case the curvature is not constant for some reason.

The trick is to not overdo the droop. Try to compare your the curvature of your bent hacksaw blade to a photo of the real thing before attempting the procedure.

I'll be trying the hacksaw blade next time myself.  I almost messed up bad using the hair dryer.  I taped the blade ends to a flat surface and put small dowel rod under the middle of the blades to the desired amount of droop.  Took the hair dryer to them on a medium heat setting and in no time one shrank a little and started to curve.  I didn't even hold the dryer still, just too much for too long I guess.  I git it most of the way back though. 

On this subject, where is the proper place for droop to begin on a Ch-53?  Or does it curve the full length of the blade?

Here is a link that shows the droop on a -53 reasonably well.
Link

This one may be useful as well
Link

Look closely at the blades and you will notice that they also have approximately 3 degrees of negative twist.  If you want to get super detailed and simulate this, the hacksaw blade method may be the easiest way to do so.

Mac

Awesome pics, especially the one from the rear.  There really isn't a whole lot of droop there that I can see but it does appear to cover the length of the blade.  I think I can see what you mean about the twist as well.  Thanks for posting the links.

hELLO humper491.

For me the easiest way is thumb and first finger of both hands clasp blade and gently  with your right hand or left which ever you are say your right handed slowly from the centre hub bend with with right hand until you reach the tip of the blade and check the droop if not enough repeat  until satisfied that's what i do but i must state gently does it.

SNAKE

There is actually a fair amount of sag in the -53 rotor system, it just isn't quite as noticeable because it begins closer to the hub than some others.  Stiffer blades don't begin to sag until further out from the center, so it appears that they sag more.  If you find a picture where you see a blade either directly from the leading or trailing edge, put a straight edge by it and you will see just how much the blades sag from the root.

the first thing you need to do is consult a lot of ref material.  Blades bend differntly and some droop a ton while others dont droop nearly as much.

I have always bent them by hand , sometimes a blade needed a little heat from a hair dryer, but not too often.

yup, bending blades especially when you are building  big helicopters in big scale is really a challenge. thanks to Hasegawa though for "pre- bending" their rotor blades straight from the box.. i'm working on a Seaking  in 1/48 from hasegawa and very happy to find the rotor blades already drooped. just got to assemble the heli in ready to fly position as i dont think these blades droop much in its folded position.. 

When folded, the blades will droop just as much as unfolded unless they are supported.  I am no expert on Navy operations but I suspect that supports are used if the rotor system is going to remain folded for any extended period, definitely during shipment.