Hi Mathys, Thanks for your post. I am interested in your tail dolly. We have to push our Dimona into its hangar sideways which has its own set of problems. I have built a trolley for the main wheels but still use a temporary one for the tail wheel so am interested in what you have in mind for the rear end. With fuel on board and the distance of the mains from the c of g the weight as you know is real heavy. Also needs to be a 1 man job The one for the mains uses a couple of over centre frames and 4 big wheels. It works real well. I'm still figuring out the tail one. Have a steel frame with 4 smaller wheels and hope to make a clamp for the axel bolt and a tricky over centre lifting arm. The tow out frame is real simple.... Two PVC circular blocks with holes on the centre clamp Over the tail wheel axel bolt and a steel frame bolted to them to a trailer hitch. If you are interested In our system, I can send you some pictures as I am interested in your tail wheel dolly. Best regards
Ian Williams ZK-GCB Sent from my iPad > On 25/10/2015, at 8:46 pm, Mathys Kuhn <[email protected]> wrote: > > Hi Everybody > Some final feedback on the tail wheel shimmy I have experienced: > I have changed the tail wheel to a softer type wheel and the shimmy stopped > immediately. Although the previous tail wheel was only on the aircraft for > less than 10 hours of flying time, the aircraft stood in the hangar for > almost a year without flying. This might also have been a cause for the > shimmy. I am now in the process of manufacturing a dolly wheel for the Dimona > to take the load off the tail wheel for extended periods on the ground. > > Thanks to everybody for the valuable information and help with this problem. > I certainly appreciate it > Kind Regards > > Mathys Kuhn > Training Captain > T: 0825685614 > C: 0825685614 > F: 016 9330248 > e: [email protected] > > From: [email protected] [mailto:[email protected]] On > Behalf Of Michael Stockhill > Sent: 06 October 2015 03:19 AM > To: [email protected] > Subject: Re: [DOG mailing list] More on shimmy and tyres > > We used to have much luck in the past balancing wood props by adding another > coat of paint or more to the light end of the prop. > > > MLS > > On Mon, Oct 5, 2015 at 4:33 PM, wallace barnes <[email protected]> > wrote: > Hi All > Just putting in my little bit. To balance tail wheel and dynamic > balance of prop go to a Tyre place and get a card of stick on weights as used > on mag wheels there are a range of weights on each card. We have added 10 gms > to our new prop and the results are amazing. > cheers Wally > > > > On 5/10/2015 3:13 PM, Ian Mc Phee wrote: > Rob > Thanks for that. I would never have thought of balancing tailwheel. I use > square Mc ready tyres 6pr 250x4 as am sick of the bunnings ones from China. > > I can say with PIK20E prop it really helps as with falke fixed pitch prop but > even better do a dynamic balance on the prop. > > Ian Mc Phee > 0428847642 > Box 657 Byron Bay NSW 2481 > AUSTRALIA > > On 5 Oct 2015 4:10 pm, "Rob Thompson" <[email protected]> wrote: > Don't forget that if your tail wheel is out of balance it will be much more > prone to shimmy. > > A static balance can be acheived quite easily. > > A tiny bit of lead sheet flashing cut out to size and glued, screwed or > doubled sided taped in place will solve the problem. > > Just support the well oiled shaft and see which side of the wheel rotates to > the bottom. > > > cheers > Rob > > Rob Thompson > 0429 493828 > Please note that my new email address is [email protected] > > > From: [email protected] > To: [email protected] > Date: Mon, 5 Oct 2015 11:21:28 +1100 > Subject: [DOG mailing list] Shimmy and tyres > > I have suspected for a while now that the square profile tail wheel tyres are > less prone to shimmy than the round ones. > > Yesterday we changed to a round profile and for the first time in ages got a > bit of shimmy on bitumen on the take off roll. Landed on grass but I will > test the theory more sometime soon. > > Rob > > Rob Thompson > 0429 493828 > > > > Date: Mon, 5 Oct 2015 11:09:19 +1100 > From: [email protected] > To: [email protected] > Subject: Re: [DOG mailing list] H36 Tail wheels > > I found out my previous message didn't get through because of file size. Here > it is again. > > Michael is on the right track. The vertical shaft on any castor wheel has to > be exactly vertical. > > What happens with the Dimona h36 is that shaft gets bent slightly due to > potholes etc. and from then on you have shimmy. The bend can be barely > visible. > The more the bend the more the excitement. I have had both the straight > tailwheel and the damped one and the only difference is in height. > > I have seen a " repaired " one that was made stronger and that stuffed the C > of G. The one with the damper bracket weighs 725 grams. > > A new part definitely fixes the problem. > > Regards, > John. > > On 3 October 2015 at 00:08, Michael Stockhill <[email protected]> wrote: > I don't have the W&B info on my friend's H-36 here, but I do remember > weighing it and finding the numbers way aft, somewhere on either side of the > aft limits when flown solo. My own H-36 is fine. I can't account for the > difference, suspecting perhaps an undocumented heavy repair, and the very > lavish heavy beautiful refinish that was done. It has been a few years, but > I did some calculations for adding a weight in the nose, but with the > relatively short arm it was impractical. > > Life is great, > > > MLS > > On Thu, Oct 1, 2015 at 8:19 PM, Nigel Baker <[email protected]> > wrote: > I am surprised by your comment on them being tail heavy. > I have weighed 4 different H36 aircraft and they all came in close to each > other in C of G. > See attached for my own aircraft. > Cheers. > Nige. > > > From: Michael Stockhill > Sent: Friday, October 02, 2015 11:04 AM > To: [email protected] > Subject: Re: [DOG mailing list] H36 Tail wheels > > My friend tried a later-model tailwheel fork with the rubber dampers on his > H-36. I wasn't present, but recall that it is far heavier and put an already > tail heavy bird way out of CG limits. There were other issues that prevented > retrofit, if I remember correctly. > > > MLS > > On Thu, Oct 1, 2015 at 4:56 PM, Rob Thompson <[email protected]> wrote: > The early H36 models had a straight un-damped tail wheel fork which, due the > wheels being forward of the centre of gravity and the heavy tail weight can > induce some quite nasty oscillations. > > As a result of this Hoffman later introduced a new tail wheel which has shock > absorbing rubbers. This reduces dramatically the oscillations but is more > prone to shimmy. > > If the tail wheel cables are too tight the steering becomes VERY responsive > to the slightest pedal movement. If the cables are too loose you get shimmy. > Takes a bit of experience to know when it is just right. Real pain when you > have to take the tank out each time to get it right! > > > > Rob Thompson > 0429 493828 > Please note that my new email address is [email protected] > > > From: [email protected] > To: [email protected] > Date: Thu, 1 Oct 2015 21:09:03 +0200 > Subject: Re: [DOG mailing list] Morning Glory Cloud Documentary > > Most interesting and helpful thanks Michael. My Dimona is also a bit of a > beast on the ground compared to other taildragger aircraft I have flown. I > will keep you pisted. Thanks for taking the time to write the detail. > Regards. > Thys > > > > Sent from my Samsung Galaxy smartphone. > > > -------- Original message -------- > From: Michael Stockhill <[email protected]> > Date: 01/10/2015 20:57 (GMT+02:00) > To: [email protected] > Subject: Re: [DOG mailing list] Morning Glory Cloud Documentary > > Hi, Mathys, > > I own an H-36 and also maintain one belonging to a friend. Between the two > of us, we have had some interesting tailwheel issues. My bird was the > scariest tailwheel aircraft I had flown ( about 800 hours in various Super > Cubs, Cessna 180's and 185's and DH Beavers, etc.). If you breathed on the > rudder pedals during takeoff or landing when the tailwheel was on the ground, > it would threaten to leave the runway, and on two or three occasions I > suffered PIO (pilot-induced oscillations) that shook my teeth. What I > finally discovered was a logbook reference to a tailwheel fork repair. The > fork was rewelded at that time with absolutely no trailing rake. We rebuilt > it with 7 degrees aft rake and that demon was tamed. It now actually reminds > me of a normally operating aircraft. > > In the case of my friend's Dimona, most landings resulted in scary tailwheel > shimmy--I thought it would take off the tailboom. He mitigated this at first > by making wheel landings and holding the tail off as long as he could. On > the couple times I experienced it, I braked as much and as soon as possible > to get slowed down. We tried various tailwheel tire pressures and checked > balance, etc.. It has been a while, so my recollection is a bit vague, but > what I did discover by looking at the tailwheel fork while installed, the > shoulder of the weldment where the vertical shaft enters the lower flanged > spacer was not parallel with the face of that spacer. Upon disassembly we > were able to discern some bending of the shaft at that point (the shoulder of > the weldment and the tailwheel vertical shaft). We had a whiz of a > machinist fabricate a new shaft and other parts of the tailwheel fork. I > test flew it afterwards and it was a different airplane. Rudder cables were > also replaced at a later date. > > Hope some of that is of help to you. > > Michael Stockhill > Polson, Montana, USA > > On Wed, Sep 30, 2015 at 3:40 AM, Mathys Kuhn <[email protected]> wrote: > Hi Everybody > I operate a mid 80’s model Hoffma Dimona in South Africa. Lately I started > experiencing a significant tailwheel shimmy at low speed after landing on a > tar runway. Has anybody ever experienced something similar? ANY ADVICE? > Many Thanks > > Mathys Kuhn > Training Captain > T: 0825685614 > C: 0825685614 > F: 016 9330248 > e: [email protected] > > From: [email protected] [mailto:[email protected]] On > Behalf Of Ian Williams > Sent: 23 September 2015 10:56 AM > To: [email protected] > Subject: Re: [DOG mailing list] Morning Glory Cloud Documentary > > Apparently only able to be viewed in Australia. > > Sent from my iPhone > > On 23/09/2015, at 13:05, Rob Thompson <[email protected]> wrote: > G'day All, > For those of you who missed it, the Morning Glory Cloud Documentary is on SBS > "Catch Up" > http://www.sbs.com.au/ondemand/video/521484355510/secrets-of-a-strange-cloud > > > cheers > Rob > > Rob Thompson > 0429 493828 > P Please consider the environment before printing this e-mail. > > > Attention: > Please note: This email and its content are subject to the disclaimer as > displayed at the following link http://www.comair.co.za/disclaimer.html. > Should you not have Web access, send an email to [email protected] and > a copy will be sent to you. > > > > > > > > > > > --------------------------------------------------------------------- > You are subscribed to the Dimona Owners Group mailing list. > To unsubscribe, send email to: [email protected] > > > > --------------------------------------------------------------------- You are > subscribed to the Dimona Owners Group mailing list. To unsubscribe, send > email to: [email protected] > > > P Please consider the environment before printing this e-mail. > > Attention: > Please note: This email and its content are subject to the disclaimer as > displayed at the following link http://www.comair.co.za/disclaimer.html. > Should you not have Web access, send an email to [email protected] and > a copy will be sent to you. > >
