Graupner Jet Drive Installations?

[Pibber]

I'm in the process of building a 1/12 scale 31-PBR Mk II (Pibber). The original runs on twp Jacuzzi jet pumps so keeping with authenticity, Graupner jets would be the way to go. Problem so far is that the Pro-2 has too high a profile and doesn't clear the hulls lazarette area, they are too high. The Pro-2 Small appear to be the same height only shorter in length. Hobby Lobby has the new Graupner Mini Jets that run off 500 motors but I can't seem to get any spec information from them. Another problem is the thrust reversing units which all seem to lift out of the way of the thrust port and again the lazarette interferes with this operation. I was told that if i shave down the intake opening, this will lower the profile and bring the output ports deeper in the water which is good. I don't have the equipment to precisely cut off the intake port correctly and even if I do this it will end up making the overall intake opening huge!!! So, there is my current dilema with this model build. Has anyone built a PBR and how did you install the drives, did you incorporate the reversers or did you end up going with props and rudders??? This is an option I am considering at this point but would like to stay with accuracy in detail. Just to add fuel to this little fire; using the thrust reversers adds just another problem with radio channeling. I'll definitely need to go two servos per reverser. Any help will be appreciated !!!!!!!!!!!!!!! :eek: :confused:

[Umi_Ryuzuki]

The tallest part of the mini jet is the motor mount.
That fits a standard 500 series can, 1.375". Everthing
is centered on that. The length of the drive
housing/motor mount is 3.25" The flange of the output
cone is 1.25"

For thrust reversers, you could gang your control rods by
soldering them together in an "h" or "Y" configuration and
use a single servo.

:)

[Pibber]

Thanks for the response Umi. This build is driving me over the gunwhales !!! Here are some pics of the hull and with the Pro-2 drive sitting in the hull.
Pic#1...The lazarette step is 3cm to aft x 4cm verticle.
Pic#2...Inside view of lazarette area.
Pic#3...Shows Pro2 drive sitting in stern area.
Pic#4...Shows the Pro2 over the lazarette step by 8mm so the flange is actually way more.
The Pro2 Short is the same height wise but shorter in length.
As you can see the problems are fairly clear. "What is a boy to do?"
The only draw back I can see using the Mini thruster is that the reverser flips up out of the way of the outlet port which would be blocked by the lazarette step. If the Mini will fit, I could always just install the steering nozzle without the reversing clamshell; I guess.

[mxz70017]

I used the Graupner Mini jet In a 26 inch Shockwave Proboat Hull.I didnt use my reverse bucket so I just went an measured It.You could rotate the jet outlet.90 degrees either way on your port an starboard side.Then make a flat side on each.That will fit under your step on both sides.The jets thrust wouldnt be straight down.But rather pushing to push sides inwards.My cousin had a real 28 foot jetboat.They dont reverse well to begin with!!!Even the real ones...LOL!!But due to the circumstances I think It will still work ok for you.My bucket on the Mini jet Measures 60mm wide an 30mm deep.The stern of the Shockwave was 50mm.The outlet diameter of the jet was 32mm.It gave me a 18mm clearance.

[GreenAmphibian]

Hi, I have built a 1/12th PBR from Mosquito Boat Hobbies and installed the Graupner Mini-Jets in it with two Traxxas Verlinion brushless motors. The performance is faster than the originals. I am not a big fan of their (Graupner's) reversing buckets, but they do work. The Mini's fit without to much fiddling with the stern of the boat. You can run both the turn and reverse functions with one servo each and connect them together. I posted some pictures of mine on here awhile ago. I'll be happy to take some upgraded pictures since I have made a bunch of changes since then to the boat. Water cooling, servo controlled led lights, individual control of motors and reverse buckets, and 2.4g raido.

[Pibber]

Hi, I have built a 1/12th PBR from Mosquito Boat Hobbies and installed the Graupner Mini-Jets in it with two Traxxas Verlinion brushless motors. The performance is faster than the originals. I am not a big fan of their (Graupner's) reversing buckets, but they do work. The Mini's fit without to much fiddling with the stern of the boat. You can run both the turn and reverse functions with one servo each and connect them together. I posted some pictures of mine on here awhile ago. I'll be happy to take some upgraded pictures since I have made a bunch of changes since then to the boat. Water cooling, servo controlled led lights, individual control of motors and reverse buckets, and 2.4g raido.
Wich model hulll was it? The mkI doesn't have the stern step as in the mkII. I'm thinking the mini's should work . Thanx

[mxz70017]

Hey If you need any Measures or help.Let me know I have one Installed an I can take some measures for you ok.Ive also seen In my travels an readings.The reverse buckets need a little help satying in place on the jet cone.I also see why they say that to they dont well exactly fit in the tightest of ways for sure!!!!

[GreenAmphibian]

Mine is the Mk II with the lazerette step on the rear transome.

[Pibber]

If it's not too much trouble to show me some pics of your setup, that would be terrific. I'm on the verge of placing an order with my online supplier and if I haven't made up my mind which way to go, props or jets, I'll likely dump the idea of jets for props and inevitably regret it...

[newPTboater]

I built the PBR MK II from Mosquito Hobbies and had the same issue, though I used KMB jets. To solve the problem, I moved the jets foward in the hull and built extensions from PVC (picture attached) that allowed the exit to be under the step. There were no issues with performance.

[newPTboater]

forgot to add the picture of the exterior, showing reversing mechanism

[Umi_Ryuzuki]

Moving the jets forward is a great idea NewPTboater.
The advantage of fitting the Pro2 , is that, like the KMB jet,
the reverse bucket doesn't rise above the line of the jet output.
It merely shifts some diversion plates on the steering housing.

[Pibber]

If I use the Graupner Pro2 Small and homemade extension tubes to bring everything under the step; then that should also work.............. yes?
I got an email from the hull builder and he says the mini jets will work but they are powerless with the 500 motors but the 600's will fit the jets. The problem is that the mini jets use a two bladed impeller which is weak, low nozzle pressure therefore the 600's to get the bite required. The problem with the Pro2 Small is that like all the other reversing units, the bucket tilts up to get out of the way. The Pro2 reversing nozzle flips up to engage and sits flush under the nozzle when in the forward position, which is the desirable set up. OMG what to do????? What's that? Did someone say props?

[retoabcr]

Try the site RC Universe site cause they have a few guys who have gone thru h*** and high water in building Villian jet boats galore. Do a search on jet boats. I spent money on a small already jet boat but put a 05/540 motor in and found out rpm isn't the key. Rpm over 22,000 and a brushed motor didn't have enough thrust due to small impeller. The 29mm impeller would work better than the 19mm impeller. Now with 25mm to an inch that gives 9mm and about 40% more thrust. Now this #'s when 25mm divided by 5 is 5mm x 2 =10mm. Figuring- 5mm is 20%. Hope you don't think your a dummy by the way i typed by any means but trying to help. The recommendations by each company are well thought out so the customer gets satisfaction from their product. U-joints are a headache, so if you can get around to not having them do so, you'll thank me for saying so; been there, done that!!!!!! Reason they use a 700 motor cause rpms are less than a 05/540 per volt. I have a mini and impeller is 19mm and 500 tore up the mini impeller and raise cane with u-joints proper like. Storage in rafters. No comment!

[Umi_Ryuzuki]

I thought you were talking about the PRO-2 booster with a reverse bucket.
The red reverse mechanism is more like the KMD drives.

http://www.hobby-lobby.com/jetdrives.htm

[nick30head]

hey fella's, i'm in the middle of converting my NQD highwind to mini-jet, i got a graupner 500 motor at the moment but am upgrading to brushless when it arrives, my foto's are on here to see how the build is going, i dont see anything wrong with converting to mini-jet, there's only so much you can do with prop's, rudder's, bow thrusters and so on, goodluck to everyone who use's them and i'm only using my brushed motor for testing purpose's

[nick30head]

hey Umi, rustbucket told me about you, i also got the graupner mini-jet in my highwind boat, i'm going brushless with it but if that dont work then i'll go for the graupner 600 but the problem is i noticed on the cornwallmodelboats.co.uk site that there is 4 types of 600 motor and am unsure which one to go for IF and WHEN i might need one, cheers nick

[Umi_Ryuzuki]

I would imagine that you would use the 7.2volt motors, as you would want
to match the battery pack you are using.

:)

[nick30head]

i beleive 2 of them are 7.2v and the others are 8.4v, i would stick with the 7.2v as i have a mains charger because thats what i have in all my boats, cheers umi

[HomePort Models]

I have installed the Graupner Mini jets into my LCS1 model, in 1.96 scale and they are great. The only problem was the reverse buckets didn't fit on the model so I left them off. To my surprise, the jets can reverse and give me enough power to stop the boat.

You can see some photos at www.homeportmodels.com.
I will be uploading some movies this weekend if the rain holds out.

Eric
Homeport Model Ships.
www.homeportmodels.com